Narrowband can manufacturing

Abstract

1. A system for use in the manufacture of cans for cleaning, decorating, and / or spraying paint onto the interior surfaces of cans, comprising a first station, a second station, and a third station, wherein the first station comprises a first array of semiconductor-based narrowband irradiators arranged to irradiate and dry cans passing through a mesh belt or open space belt of a collecting conveyor or an in-line conveyor, the second station comprises a second array of semiconductor-based narrowband irradiators arranged to irradiate and cure ink applied to the exterior of the cans as they are transported on the conveyor, and the third station comprises a third array of semiconductor-based narrowband irradiators arranged to individually electrically heat the interior surface of each can that moves into a curing zone using optical elements positioned outside the open end of the can.

Description

Technical Field

[0001] This application claims priority based on U.S. Provisional Patent Application No. 63 / 037,437, filed on June 10, 2020, "Narrow Band Can Manufacturing" and U.S. Provisional Patent Application No. 63 / 094,601, filed on October 21, 2020, "Narrow Band Can Manufacturing", and the entire contents of the two above-mentioned U.S. Provisional Patent Applications are incorporated herein by reference.

Background Art

[0002] In the manufacturing process of two-piece aluminum or steel beverage cans, a coating is necessary to prevent the raw aluminum or steel, the raw material for the can, from directly touching the product that will ultimately be filled into the can. Certain liquids can spoil if they come into contact with the aluminum material in the can. Other liquids can undergo harmful chemical reactions with aluminum, compromising the integrity of the container. For example, beer will be ruined if it comes into even slight contact with raw aluminum. Soft drinks are often acidic, which chemically etches the surface of the aluminum, weakening the strength and integrity of the already very thin aluminum. In addition, it can negatively affect the product in terms of altering the taste. Some processes involve painting the aluminum material while it is still in a flat, cut, elongated state or coil stock before it is formed into the final can shape. However, most cans are painted after the starting material, the flat coil stock, has been formed through a molding process. Modern manufacturing processes for cans used for food or beverages generally fall into two categories. Specifically, one process involves a draw-redraw process (D&R), and the other involves a draw-and-iron process (D&I). The D&I process is sometimes called the draw-wall-iron process or DWI. In both processes, a drawn cup is manufactured (usually) from a flat coil stock. This cup is then further drawn and machined into a deeper but final-sized cup. In the second step of the D&I process, the cup walls are continuously "ironed" until they reach the desired precise thickness and dimensions. Through considerable engineering and experimentation, the process, as well as the final unfolded shapes of both the can bottom and the final can neck in subsequent processes, have been examined.Precise shape geometry is crucial to ensure that the finished can withstand the pressure exerted by the gases from the liquid food or beverage filled inside. This structural molding aims to hold the pressure along the sidewalls, but ultimately needs to substantially prevent the bottom from doming up, a phenomenon known as bottom inversion failure.

[0003] To illustrate in more detail, refer to Figure 6, which uses a typical draw-and-iron process (D&I or DWI) as an example. Figure 6 shows an example of process 600 for forming a can using D&I. As shown in the figure, the can is formed using an uncoiler 602, a lubricator 604, a cupper 606, a body maker 608, and a trimmer 610. Those skilled in the art will understand the form and function of these elements in a typical D&I process.

[0004] After being shaped into straight-walled, neckless cans, they are washed using a washer (612) and dried at approximately 400 degrees Fahrenheit using a gas drying oven (614), for example, before undergoing a coating process that includes an internal coating process.

[0005] The coating process begins by optionally applying the ink base coat to the outside of the can using a basecoater (616), and then drying the applied base coat using an optional basecoater oven (618) operating at approximately 400 degrees Fahrenheit. Next, the can is passed through a decorator (620) to apply the ink pattern to the outside of the can, and then through a bottom coater (622) to apply a protective coating layer to the bottom of the can. The can is then sent to a deco oven (624) (also operating at approximately 400 degrees Fahrenheit) to dry the applied external coating.

[0006] Next, the internal coating process for painting the inside of the can is initiated. This process typically involves a single line of cans passing through an internal coater (626) where a spray gun operates, either on an indexed star wheel or a continuous-travel star wheel, to coat the inside of the can. The spray gun is highly developed to direct a very fine mist of wet paint onto the can, ensuring all surfaces are covered. The can rotates under the spray gun while it is operating, ensuring a uniform coating of the 360 ​​degrees of the can's inner circumference. Generally, the goal is for the can to rotate 2-5 times while spraying the inside. The wet paint appears as a thin white paint coat adhering to the entire inner surface of the can. The can is rotated at high speed during the process, using centripetal force to distribute the paint evenly. It is crucial that the spray coating is applied to the correct thickness to adequately cover the stock of the aluminum or steel can. To do it properly, it should not be too thin or too thick. If applied too thickly, bleeding and thick spots may occur, potentially leading to improper curing and wasted paint. Immediately after the spray coating process, the cans need to be thermally cured in an oven known as an IBO (inside bake oven 628).

[0007] The single rows of cans coming out of the spray coater are sent to a group conveyor. On the group conveyor, dozens of cans are nested together across the 30-80 inch width of the conveyor, as close together as possible. The belt conveyor that passes the cans through the IBO(628) is designed to withstand the rigors of repeated high temperatures so that the belt material can safely pass through the oven and carry the cans to the curing oven. Passing through the curing oven typically takes 2-4 minutes. The oven usually has multiple heating sections through which the cans pass progressively. In a typical IBO oven configuration, the cans are introduced into the first section of the oven, where they are exposed to 200-270 degrees Fahrenheit for about 60 seconds as preheating. In section or zone 2, the temperature is raised to 270-400 degrees Fahrenheit for another 60 seconds. In the final section or zone 3, the temperature is typically held at 380-450 degrees Fahrenheit for about 60 seconds for the final curing. The can will stay in the oven for a total of approximately 180 seconds. This time may vary slightly, but this is typical.

[0008] When a can that has been transported in a batch leaves the IBO, if it has been properly cured, the epoxy coating on the inside should appear substantially transparent. Transparency is one indicator, but it does not guarantee that the paint is fully cured. To be certain, this needs to be tested in a lab. The concept of the IBO is to gradually raise the temperature of the cans that have been transported in a batch to the full carrying temperature and to ensure that it is held at 380-450 degrees Fahrenheit for at least a minimum number of seconds. This is the time required for the linking or linking process necessary for the epoxy paint to be properly and completely cured to begin. Once started at this "time at temperature," the linking process will continue until fully cured, provided that the temperature is actually held at 375 degrees or higher for the specified time. As mentioned above, a "transparent" compound does not mean that it has been properly cured. It will appear transparent even if it was not started at the correct linking temperature if a slightly lower temperature x time was provided. Furthermore, if the temperature is too high or the curing time is too long, the coating may be over-cured, resulting in yellowing or blistering. For example, if a coated can is held at a high temperature for 15 minutes, visible yellowing and blistering will occur, which is clearly not an acceptable curing result. This usually occurs when the oven conveyor stalls for some reason while a large number of cans remain in the oven. Beverage cans typically have 80-150 mg of internal coating by total weight that needs to be properly cured.

[0009] After the cans leave the IBO (628), they are sent to a waxer (630) for further processing. After processing in the waxer is complete, the can forming process is completed using a necker (632) and a flanger (634), as is known to those skilled in the art. A light tester (636) may also be used. Finally, the formed cans are sent to a palletizer (638).

[0010] This process is used worldwide and is widely accepted as the standard for two-piece cans used for the safe packaging of food and beverages. The same or very similar processes are commonly used for other types of cans.

[0011] However, current IBO ovens, in particular, consume an incredible amount of energy. Most ovens are natural gas-fired, with some being electric. Both types consume a very large amount of energy and occupy a large amount of floor space. Because the belts carrying the cans pass through the ovens 24 hours a day, 365 days a year, and are subjected to high / low temperature cycles, the ovens require extensive maintenance. All components of the bearings, drivetrain, guides, and belts themselves are subject to continuous thermal and mechanical wear. Furthermore, considering the fossil fuel-based energy source of typical ovens, there are sustainability and air pollution issues around IBO ovens. In addition, typically, five large electric motors totaling approximately 95 horsepower are required to drive the belts and continuously ventilate, exhaust, and purify the oven-related air.

[0012] In the can manufacturing industry, it is well known that the strength of the aluminum used to make the cans decreases depending on the actual time spent in IBO (Integrated Burning Occlusion). It is widely recognized that exposure to high temperatures for 2-3 minutes causes a tempering / annealing effect that weakens 3004 aluminum alloy. While annealing usually takes considerably longer than this time, it is thought that annealing occurs in cans because, in very thin aluminum, heat can penetrate completely and begin to affect the grain structure virtually immediately.

[0013] Taking into account the effects of this tempering / annealing process, it becomes necessary to manufacture cans with higher strength than the final specification. As a result of passing through the IBO oven, cans lose approximately 8-10% of the bottom reversal strength required for proper performance. The pressure containment strength must be maintained at 92-95 PSI for carbonated beverages and 105-110 PSI for beer before bottom reversal occurs. Because such rapid softening, weakening, or annealing has the effect of reducing the tensile and yield strength of aluminum alloys, aluminum cans need to be thicker to obtain the required strength compared to unannealed cans.

[0014] Furthermore, in the manufacturing process of two-piece cans, such as aluminum or steel beverage and food cans, it is necessary to apply heat generated in an oven to the can for various purposes, not just to cure the inside of the can. Roughly speaking, heating is performed in drying the can after the washing process, curing the ink after the decoration process, and in the curing of the can's interior coating and the final deep curing of the decorative ink, which is performed simultaneously. U.S. Patent Application No. 16 / 853,536, filed April 20, 2020, “System and Method for Curing the Inside of a Can,” details can curing, including the use of a narrow-band irradiation device, and is incorporated herein by reference in its entirety. However, in traditional or conventional can manufacturing plants, all three types of ovens continuously use very large amounts of natural gas. Gas drying ovens used to dry cans after washing (e.g., 614 in Figure 6) are configured to allow for very wide-width collective transport with the can's open end facing downwards to allow drainage from the can. The conveyor width varies depending on the plant's throughput, but is often 20 to 40 cans the width of a standard 12-ounce can. The drying oven is set to a temperature of 400 to 420 degrees Fahrenheit, and is usually maintained at 25 to 50 degrees lower than the actual set temperature. The time spent passing through the oven is typically 1.5 to 2.0 minutes at a typical conveyor belt speed of 15 to 25 feet per minute.

[0015] The washing process consists of multiple stages, usually six. After the cans leave the body maker, they are covered with a drawing fluid / cooling compound used to improve the finish. Before further processing of the finished cans, this needs to be washed off to clean them. After the cans leave the body maker, they typically slide down a series of tracks onto some kind of conveyor, where they merge with many other cans, and the combined cans form a wide, continuous flow on a consolidation conveyor. At this point, the cans are upside down, so gravity causes the water to flow off quickly. The can assembly slowly passes through a washing machine, where hydrofluoric acid is sprayed (usually) in two consecutive steps. Most of the acid drips off, and deionized water is sprayed in three or four consecutive rinsing steps, which is expected to rinse off the remaining acid from the inside of the cans. Subsequently, the can assembly is introduced into a drying oven. Most of the water drips off, but some still remains. The actual purpose of a drying oven is to heat the water to evaporate it from the can, leaving it completely dry. Since bulk combustion hot air ovens do not have the capability to heat only the water, the can is also heated, reaching approximately 400 degrees Celsius, and the can remains at that temperature for most of the 1.5 to 2.0 minutes it passes through the drying oven. At this temperature, it takes a very long time to dry the can, resulting in a surprising amount of annealing or weakening of the aluminum. Because aluminum is very thin and an excellent conductor of heat, the heat quickly penetrates throughout, initiating a process of grain growth and weakening.

[0016] The oven, sometimes called a pin chain oven or deco oven (e.g., 624 in Figure 6), is positioned to receive cans at the decorator's exit. Its overall purpose is to transport the cans through the drying oven without the newly decorated cans touching anything. Even the slightest touch will cause the still-wet ink to rub off and stain. So, let's describe the unique appearance and structure of the pin chain conveyor. At its heart is a link belt, or motorcycle chain-style "belt," configured to move in a zigzag pattern around a series of sprockets, which travels along a meandering or zigzag conveyor path within the oven. The purpose of the winding conveyor path is to significantly increase the time the cans stay in the oven, allowing sufficient time for the ink on the cans to dry. Each can rests on a pin that is slightly longer than the inner depth of the can. Each pin is effectively an extension of the hinge pin that engages with the sprocket of each link. The spacing varies, but generally, each can is positioned so that there is approximately a gap between them roughly corresponding to the diameter of one can. The belt moves at high speed to accommodate the unloading of as many as 2800 cans per minute from the decorator. The pin chain conveyor belt winds along a plane and passes through the oven. This plane is tilted backward so that gravity helps hold the cans in place as they pass through the oven. The oven is gas-fired and functions like a convection oven, with blowers blowing superheated air onto the cans, resulting in a high level of noise. Often, the set temperature is in the range of 450 degrees, but some sections of the oven are open and have high airflow, so the temperature actually maintained is 60-90 degrees lower than the set temperature. By default, the pin chain oven also substantially heats the plant. Again, depending on the plant specifications, cans typically stay in the pin chain oven for 15-25 seconds.

[0017] All three of these large ovens are inefficient in that they heat far more than the cans they are trying to heat. They burn large amounts of natural gas or hydrocarbon-based fuel, thereby largely heating the air, which in turn secondarily heats the cans and paint / water. This two-stage heating process is a major reason why heating the cans is slow and inefficient. Furthermore, these ovens consume a great deal of electrical energy, requiring numerous high-horsepower motors to operate not only the conveyor itself but also numerous fans to induce and concentrate heat, as well as to remove impurities from the exhaust and ensure proper ventilation. The combination of the three ovens creates extremely high-temperature plant conditions, resulting in an uncomfortable working environment and potentially dramatically increasing HVAC costs depending on the plant's location. For plants in regions of the world where air conditioning is desired or required, this extra heat load represents enormous energy consumption and contributes significantly to the carbon footprint.

[0018] Because gas drying ovens expose cans to such high temperatures for 1.5 to 2.0 minutes, as per internal cleaning, they contribute to annealing or weakening, albeit to a slightly lesser extent than IBO ovens, similar to IBO ovens. Similarly, this means that cans need to be made with more aluminum to have the same strength as cans that would normally have if they were not weakened. Thus, drying ovens not only use very large amounts of hydrocarbon fuel and electrical energy, which also results in high maintenance costs, but they also weaken the cans, reducing their final strength and performance.

[0019] Pin chain ovens cause similar problems, although the weakening is slightly reduced with shorter exposure times. Cans typically stay in a pin chain oven for 15-20 seconds, with a maximum set temperature of 430-460 degrees Fahrenheit. Since annealing is an effect of time and temperature combination, pin chain ovens contribute even more significantly to weakening and annealing effects. The pin chain itself has many moving parts that require lubrication. In an attempt to maintain sufficient lubrication, the pin chain may be over-lubricated, leading to contamination problems or ongoing housekeeping. The pins themselves are often prone to bending, causing their own problems such as loading, unloading, and crashing. Again, high maintenance costs, high hydrocarbon fuel costs, and can performance degradation are all problems that can manufacturing plants want to reduce or eliminate. [Overview of the project]

[0020] In one embodiment described herein, a system for use in the manufacture of cans, for washing, decorating, and / or spraying paint on the inner surface of cans, comprises a first station, a second station, and a third station, wherein the first station irradiates and dries the cans through a mesh belt or open space belt of a mass conveyor, or through a serial conveyor. The system includes a first array of semiconductor-based narrowband irradiators positioned to individually irradiate and dry individual cans through a select element of a conveyor, and configured to dry the cans in less than 60 seconds; a second array of semiconductor-based narrowband irradiators positioned to irradiate and cure ink applied to the outside of cans being transported on a conveyor, and configured to cure the ink in less than 20 seconds; and a third array of semiconductor-based narrowband irradiators positioned to individually electrically heat the inner surface of each can that has moved into the curing zone, using an optical element positioned outside the open end of the cans, and configured to reach a critical temperature in less than 20 seconds during the linking curing process of the paint, preventing tempering or annealing from occurring.

[0021] In another embodiment described herein, the first station is configured to dry the can in less than 50 seconds, less than 40 seconds, less than 30 seconds, or less than 20 seconds.

[0022] In another embodiment described herein, the second station is configured to cure the ink in less than 15 seconds, less than 10 seconds, or less than 5 seconds.

[0023] In another embodiment described herein, at least one of the third stations is configured to heat the can to a critical temperature for linking or cross-linking of the paint in less than 10 seconds, less than 5 seconds, or less than 2 seconds, and the paint is optimized for narrowband curing.

[0024] In another embodiment described in the present application, at least one of the first station for drying the can in less than 60 seconds and the second station for curing the ink in less than 20 seconds is configured to prevent annealing or tempering from occurring on the can.

[0025] In another embodiment described in the present application, a method for use in the manufacture of cans, which cleans, decorates and / or sprays paint on the inner surface of the can, uses a first array of semiconductor-based narrowband irradiators at the first station to irradiate and dry the cans through the mesh belt or open space belt of the collective transport conveyor or to individually irradiate and dry the individual cans through the selection elements of the serial transport conveyor, uses a second array of semiconductor-based narrowband irradiators at the second station located after the ink decorator to irradiate and cure the ink applied to the outside of the cans being transported on the conveyor, and uses a third array of semiconductor-based narrowband irradiators at the third station to individually electrically heat the inner surface of each can that has moved into the curing zone to reach the critical temperature at which the paint on the inner surface of each can in the series of production cans arranged in series using the optical element located outside the open end of the can allows the paint linking curing process to proceed, and in each of these three stations, a drying or curing function is performed in less than 20 seconds to prevent annealing or tempering or weakening from occurring on the can.

[0026] In another embodiment described in the present application, the ink cures in less than 15 seconds, less than 10 seconds or less than 5 seconds.

[0027] In another embodiment described in the present application, the inner surface paint reaches the critical temperature at which linking or cross-linking proceeds in less than 10 seconds, less than 5 seconds or less than 2 seconds.

[0028] In another embodiment described in the present application, a system for use in the manufacture of cans that washes, decorates and / or sprays paint on the inner surface of the can includes a first station, the first station including a first array of semiconductor-based narrowband irradiation devices arranged to irradiate and dry the cans through a mesh belt or open space belt of a collective conveyor, the first array being arranged within a housing and facing the inside of the can, the housing having a protective window arranged to be sealed to prevent moisture from entering the array housing, the protective window being optically transparent at the applied wavelength, the first array being provided with at least one of a reflective baffle for directing the irradiation towards the can or an optical element for selectively spreading or narrowing the beam of the irradiation, the system being configured such that the irradiation does not exit the system.

[0029] In another embodiment described in the present application, the protective window is mounted at an angle that promotes the outflow of water towards a trough or gutter arranged near the edge of the protective window, or is provided with an anti-reflection coating that functions in the applied narrow wavelength band.

[0030] In another embodiment described in the present application, the system further includes at least one fan or blower to supply a high-speed air flow to the mouth of the can to more efficiently remove water vapor.

[0031] In another embodiment described in the present application, the system further includes a second station, the second station having a second array of semiconductor-based narrowband irradiation devices arranged to individually and electrically heat the inner surface of each can that has moved into the curing zone using an optical element arranged outside the open end of the can, bringing the paint on the inner surface of each of the production cans arranged in series to a critical temperature that advances the paint linking curing process in less than 20 seconds to prevent annealing or tempering of the cans.

[0032] In another embodiment described herein, a system for use in the manufacture of cans for cleaning, decorating, and / or spraying paint onto the inner surface of cans comprises a first station, a second station, and corner cube reflectors, the first station comprising a first array of semiconductor-based narrowband irradiators arranged to irradiate and cure ink applied to the outer surface of cans being transported on a pin chain, the first array being positioned along the pin chain to irradiate the outer surface of an approaching can at a first angle, the second station comprising a second array of semiconductor-based narrowband irradiators arranged to irradiate and cure ink applied to the outer surface of cans being transported on a pin chain, the second array being positioned along the pin chain to irradiate the outer surface of an approaching can at a second angle different from the first angle, and the corner cube reflectors being positioned for each station substantially perpendicular to the tangent to the outer surface of the can and between the arrays, such that the irradiation reflected from the outer surface of the can is subsequently reflected by the corner cube reflectors and returns to the outer surface of the can at a position substantially close to the original position on the outer surface of the can from which the irradiation was first reflected.

[0033] In another embodiment described herein, the system further includes a third station, the third station including a third array of semiconductor-based narrowband irradiators arranged to individually electrically heat the inner surface of each can that has moved into the curing zone using optical elements positioned outside the open end of the can, thereby bringing the paint on the inner surface of each can of the series-connected production cans to a critical temperature that allows the paint linking curing process to proceed in less than 20 seconds, preventing tempering or annealing from occurring in the cans.

[0034] In another embodiment described herein, the system further comprises a plurality of additional stations, each comprising an array of semiconductor-based irradiators for irradiating and curing ink coated on the outer surface of a can, with each array positioned at a strategic angle so that the combination of the stations irradiates the ink on the entire outer surface of each can.

[0035] In another embodiment described herein, the system further includes a ventilation system which transports vapor containing at least volatile organic compounds from the first and second stations to a pyrolysis or catalytic decomposition unit and maintains the vapor at a threshold temperature.

[0036] In another embodiment described herein, the system further includes a drying station comprising at least one array of semiconductor-based narrowband irradiation devices arranged to irradiate and dry cans through a mesh belt or open-space belt of a collective conveyor, or to irradiate and dry individual cans individually through a select element of a series conveyor, and the drying station is configured to dry cans in less than 20 seconds.

[0037] In another embodiment described herein, a system for use in the manufacture of cans in an internal coating and curing process, in which paint is sprayed onto the internal surface of the cans, comprises a can handling system, an array of semiconductor-based narrowband irradiators, and a ventilation system, wherein the can handling system is configured to sequentially move production cans to at least one curing zone, the array of semiconductor-based narrowband irradiators is configured to individually electrically heat the inner surface of each can that has moved into the curing zone using optical elements positioned outside the open end of the can, and is configured to bring the paint on the inner surface of each can in series to a critical temperature that allows the linking curing process of the paint to proceed in less than 20 seconds, preventing tempering or annealing from occurring in the cans, and the ventilation system carries vapors containing at least volatile organic compounds to a pyrolysis or catalytic decomposition unit and maintains the vapors at least at a threshold temperature.

[0038] In another embodiment described herein, a system for use in the manufacture of cans in an internal coating and curing process, in which paint is sprayed onto the inner surface of the cans, comprises a can handling system, a broadband infrared source and a ventilation system, wherein the can handling system is configured to sequentially move production cans to at least one curing zone, the broadband infrared source is configured to individually electrically heat the inner surface of each can that has moved into the curing zone using an optical element positioned to direct irradiation to the upper sidewall of the inner surface of the can, and is configured to bring the paint on the inner surface of each can in a series of production cans to a critical temperature that allows the linking curing process of the paint to proceed in less than 20 seconds, preventing weakening, tempering or annealing from occurring in the cans, and the ventilation system carries vapors containing at least volatile organic compounds to a pyrolysis or catalytic decomposition unit and maintains the vapors and outgassing compounds contained in the vapors at least at a threshold temperature.

[0039] In another embodiment described herein, a system for use in the manufacture of cans for cleaning, decorating, and / or spraying paint onto the inner surface of cans comprises a first station and a second station, the first station comprising a plurality of arrays of semiconductor-based narrowband irradiators arranged to irradiate and cure ink applied to the outside of cans being transported on a pin chain conveyor, the arrays of the first station configured to cure the ink in less than 20 seconds, and the second station comprising a plurality of second configurations of arrays of semiconductor-based narrowband irradiators arranged to individually electrically heat the inner surface of each can that has moved into the curing zone using optical elements located outside the open end of the can, using optical elements located outside the open end of the can, thereby bringing the paint on the inner surface of each can of a series of production cans to a critical temperature that allows the paint linking curing process to proceed in less than 20 seconds, preventing tempering or annealing from occurring on the cans.

[0040] In another embodiment described herein, a system for use in the manufacture of cans, for cleaning, decorating, and / or spraying paint onto the inner surface of cans, comprises at least one of a first array of semiconductor-based narrowband irradiators, a second array of semiconductor-based narrowband irradiators, and a third array of semiconductor-based narrowband irradiators, wherein the first array is arranged to irradiate and dry cans through a mesh belt or open-space belt of a collective conveyor, or to irradiate and dry individual cans individually through a select element of a series conveyor; the second array is arranged to irradiate and cure ink applied to the outside of cans being transported in a pin chain; and the third array is arranged to individually electrically heat the inner surface of each can that has moved into the curing zone using an optical element positioned outside the open end of the can, and is configured to bring the paint on the inner surface of each can of a series of production cans to a critical temperature that allows the paint linking curing process to proceed in less than 20 seconds, preventing tempering or annealing from occurring in the cans.

[0041] In another embodiment described herein, a method for use in the manufacture of cans, for cleaning, decorating, and / or spraying paint onto the inner surface of cans, includes at least one of irradiating and drying cans through a mesh belt or open-space belt of a collective conveyor or individually irradiating and drying individual cans through a select element of a series conveyor using a first array of semiconductor-based narrowband irradiators; irradiating and curing ink applied to the outside of cans conveyed in a pin chain using a second array of semiconductor-based narrowband irradiators; and using a third array of semiconductor-based narrowband irradiators, individually electrically heating the inner surface of each can that has moved into a curing zone using an optical element positioned outside the open end of the can, thereby bringing the paint on the inner surface of each can in a series of production cans to a critical temperature that allows the paint linking curing process to proceed in less than 20 seconds, preventing tempering or annealing from occurring in the cans.

[0042] In another embodiment described herein, a method for use in the manufacture of cans in an internal coating and curing process, in which paint is sprayed onto the inner surface of the cans, includes roughly transporting the cans toward at least one curing station, where the cans are individually electrically heated at the at least one curing station using an optical element positioned outside the cans and narrowband radiated infrared energy, to bring the paint on the inner surface of each can of a series of production cans to a critical temperature that initiates a paint curing linking process in less than 20 seconds, preventing tempering or annealing from occurring in the cans.

[0043] In another embodiment described herein, each can is formed from a manufacturing tool that has been reconfigured to reduce the diameter of the cut edge of the blank used to squeeze out the starting cup for the can, thereby making the thickness of the coil stock aluminum substantially the same as before the tool was reconfigured, but making the coil stock narrower and reducing the weight of aluminum required to manufacture each can by more than 3%.

[0044] In another embodiment described herein, each can is formed using a modified can design and tools to manufacture the can from a thinner coil stock material in order to reduce the amount of aluminum used in the manufacture of the can, thereby eliminating the strength reduction caused by heating to achieve a linking curing process in less than 20 seconds, and the can having sidewall axial strength, bottom reversal strength, and overall strength comparable to that of a can thicker than the can that is cured for a longer time than the time that weakens the metal.

[0045] In another embodiment described herein, the electrical curing of the paint is performed by a narrowband semiconductor-based radiant heating system.

[0046] In another embodiment described herein, a semiconductor-based system that generates narrowband radiant energy can be switched on or off within microseconds, and can heat paint and / or cans to a curing temperature in less than 10 seconds.

[0047] In another embodiment described herein, a conveyor transports cans during the curing process and utilizes continuous rotational motion. The continuous rotational motion of the conveyor causes at least one irradiation curing station to rotate continuously in sync with the cans being cured thereby, and at least one of electrical power, cooling liquid, and control signals is connected to the at least one curing station via a rotating union.

[0048] In another embodiment described herein, at least one of a DC power supply, a cooling heat exchanger, a cooling chiller, a cooling recirculation pump, and a control system serving at least one curing station comprises a continuous rotary motion curing system, which moves in rotational motion in sync with the can so that the continuous motion of the system assists the cooling function.

[0049] In another embodiment described herein, a conveyor transports cans during the curing process and utilizes indexing rotary motion. The indexing rotary motion of the conveyor positions multiple irradiation curing stations around a turret rather than on top of it, and groups of cans are sequentially loaded into a selected number of empty stations around the turret as the turret rotates and indexes so that each can is below its respective narrowband curing station, activating the curing stations to cure the cans, and then the turret rotates and indexes again to remove the cured cans while a new set of cans is indexed to a position below the curing stations, and this series of processes is repeated.

[0050] In another embodiment described herein, the cans are individually cured in less than 5 seconds.

[0051] In another embodiment described herein, a narrowband semiconductor device emits narrowband radiated infrared energy at wavelengths that match the absorption characteristics of the paint on the inner surface of each can in a series of cans.

[0052] In another embodiment described herein, the wavelength of the narrowband radiated infrared energy used for heating is one of the following ranges: 800 nm to 1200 nm, 1400 nm to 1600 nm, and 1850 nm to 2000 nm.

[0053] In another embodiment described herein, the narrowband infrared radiation energy used for heating is generated using at least one of a semiconductor-based irradiator, a light-emitting diode (LED), and a laser diode.

[0054] In another embodiment described herein, the semiconductor device generating the irradiation comprises a multi-device array configured to combine the optical output power emitted from each of more than 10 semiconductor devices to a total optical output power of more than 100 watts.

[0055] In another embodiment described herein, the semiconductor device is a laser diode with a full width at half maximum (full width / half max output bandwidth) narrower than 20 nm.

[0056] In another embodiment described herein, the semiconductor device is a surface-emitting laser diode with a full width at half maximum (full width / half max output bandwidth) narrower than 2 nm.

[0057] In another embodiment described herein, the energy source includes an array of surface-emitting laser diodes that generate a photon energy output of 825 to 1075 nm.

[0058] In another embodiment described herein, the material / cans are handled so that individual curing of cans in a single lane can be performed at a production rate of more than 300 cans per minute.

[0059] In another embodiment described herein, multiple curing stations are arranged in parallel, with all but one lane operating to individually cure at a total throughput rate of more than 1800 cans per minute, while the excluded lane is used for necessary maintenance or for additional production as needed, thereby increasing the overall uptime level.

[0060] In another embodiment described herein, the method eliminates the use of hydrocarbon-based fuels and, as a result of rapid curing for less than 20 seconds, eliminates annealing and weakening of the aluminum in the can body, resulting in a saving of more than 3% of aluminum in the can manufacturing process.

[0061] In another embodiment described herein, a specific additive that interacts with narrowband infrared light is added to the paint in order to improve the performance or functionality of the cured paint.

[0062] In another embodiment described herein, the method facilitates the reconfiguration of paint components to eliminate BPA or other undesirable components in the paint formulation.

[0063] In another embodiment described herein, the apparatus configuration relating to the curing method can be easily started and stopped without adversely affecting the can or the manufacturing process.

[0064] In another embodiment described herein, the ability to respond in real time and immediately to modulation in the method, which can be determined from sensor information obtained from the inspection system, is implemented.

[0065] In another embodiment described herein, a system for use in the manufacture of cans in an internal coating and curing process, in which paint is sprayed onto the inner surface of the cans, comprises a can handling system and an array of semiconductor-based narrowband irradiators, wherein the can handling system is configured to sequentially move production cans to at least one curing zone, and the array of semiconductor-based narrowband irradiators is configured to individually electrically heat the inner surface of each can that has moved into the curing zone, using optical elements positioned outside the open end of the can, to bring the paint on the inner surface of each can in series to a critical temperature that allows the paint linking curing process to proceed in less than 20 seconds, preventing tempering or annealing from occurring in the cans.

[0066] In another embodiment described herein, the array and optical elements of a semiconductor-based narrowband irradiator are positioned just outside the top surface of the cut edge of the can, directing more than 90% of the narrowband infrared photon energy generated by the semiconductor-based narrowband irradiator into the interior of the can during curing, concentrating the majority of the energy in the upper half of the sidewalls, which then strike the bottom of the can by internal reflection.

[0067] In another embodiment described herein, the optical element comprises at least one microlens array, a focusing lens, and a pinhole or aperture, the at least one microlens array being aligned with each narrowband irradiator in an array of semiconductor-based narrowband irradiators to form columnar energy, the focusing lens being configured to focus the columnar energy toward and through the pinhole or aperture element into the interior of the can during curing, the pinhole or aperture providing an opening through the top of a reflective molded surface that functions to return reflected narrowband energy back into the can that would otherwise escape from the can.

[0068] In another embodiment described herein, the reflective conical surface is equipped with ventilation slots or openings to facilitate the removal of vapors from the can being cured.

[0069] In another embodiment described herein, the reflective surface is substantially conical and made of one of copper, aluminum, gold-plated metal, silver-plated material, and a highly reflective nanostructure.

[0070] In another embodiment described herein, an array of optical elements and a semiconductor-based narrowband irradiator is mounted in a housing configured to prevent infrared energy from escaping and leaking out of the housing except when passing through pinhole or aperture elements, and is configured to recirculate water cooling to maintain the array and optical elements at an acceptable operating temperature in the manufacturing curing environment.

[0071] In another embodiment described herein, an array of semiconductor-based narrowband irradiation devices includes at least one array of laser diodes arranged outside a can, the corresponding optical elements being articulated inside each can during at least a portion of the curing.

[0072] In another embodiment described herein, the optical element includes an objective lens configured to receive energy from an array of semiconductor-based narrowband irradiators via an optical system and mirror assembly, the system includes an insertion and withdrawal mechanism, the insertion and withdrawal mechanism can transfer the optical element to a can via a reflection containment plate configured to be placed on top of each can, the optical transfer of energy is aligned when the insertion mechanism appropriately positions a portion of the optical system assembly inside the can, and the irradiation is activated when the optical train is appropriately positioned so that curing occurs inside the container.

[0073] In another embodiment described herein, a system used in the manufacture of a can or container for curing paint sprayed onto the inner wall of a container includes a trackwork or conveyor for loading, a second conveyor, and at least one curing station. The loading trackwork or conveyor is configured to organize or move individual containers so that they are aligned in a line toward a second conveyor, the second conveyor is configured as a rotary turret for loading and unloading individual containers toward at least one curing station, the at least one curing station is configured as an optical system in which photon energy from at least one array of surface-emitting laser diodes passes through columnar optics and is then focused by at least one focusing lens element through a pinhole or aperture beyond which the photon energy diverges to illuminate the inside of the side wall of the covered container. The configuration includes such pinholes or apertures located at the apex of a reflective cone, which functions to reflect photon energy back into the container for further curing work, and the paint is cured in less than 20 seconds, fast enough to prevent weakening or annealing of the aluminum constituting the container from occurring, and a second conveyor means guides the containers to a third conveyor configured to transport the containers and remove them from the second conveyor and carry them away, with empty pockets available for loading uncured cans waiting to continue serial curing, and the cured containers move on the third conveyor for the next container manufacturing operation.

[0074] In another embodiment described herein, the subsequent manufacturing process includes an inspection station located on a third conveyor, the function of which is at least to verify the veracity of the coating and curing in each container by imaging the inside and searching for uncovered metal areas, and, if the image quality level of the cured coating is insufficient, to reject the container with the defective coating at a rejection station located on the third conveyor after the inspection station, and then to signal at least one of the coating system control system and curing control system to correct the respective processes.

[0075] In another embodiment described herein, a system used in the manufacture of cans or open-top containers for curing paint sprayed onto the inner surface of the container comprises an input trackwork or conveyor, a second conveyor, and at least one curing station, wherein the input trackwork or conveyor is configured to move individual containers arranged in a line toward the second conveyor, the second conveyor is configured to use a rotating table to move the containers toward and toward at least one curing station, the at least one curing station incorporates one reflector designed to redirect photon energy from an array through the top of the container opening directly toward the sprayed paint on the inner surface of the container so that the curing process is effective, and the paint is cured in less than 20 seconds, fast enough to prevent weakening or annealing of the aluminum constituting the container. The second conveyor is configured to rotate so that cured containers can be discharged to the third conveyor, while simultaneously loading new, uncured cans into available positions. The third conveyor is configured to receive the cured containers at the exit and transport them for the next container manufacturing operation.

[0076] In another embodiment described herein, the second conveyor is a rotating configuration with a plurality of curing stations arranged around it, each capable of simultaneously curing the inside of a container with infrared energy generated by at least one laser diode array.

[0077] In another embodiment described herein, the plurality of curing stations include more than eight curing stations.

[0078] In another embodiment described herein, the second conveyor is a rotary configuration comprising a plurality of curing stations that rotate synchronously with the containers, so that curing can continue without starting or stopping the rotation of the table, and is connected to the curing stations via at least one of power signals, cooling signals, and control signals via at least one of the rotary unions.

[0079] In another embodiment described herein, the loading track function or conveyor is configured to use gravity to sequentially advance containers in series and to use the pressure of gravity to feed individual cans onto a second conveyor.

[0080] In another embodiment described herein, a system for use in the manufacture of cans in an internal coating and curing process, in which paint is sprayed onto the inner surface of the can, includes a can handling system, a broadband infrared source, and a control system. The can handling system is configured to sequentially move production cans to at least one curing zone, and a broadband infrared source is positioned to electrically heat the inner surface of each can moving into the curing zone individually, using an optical element positioned to direct the irradiation to the upper sidewall of the inner surface of the can, and is configured to bring the paint on the inner surface of each can in a series of production cans to a critical temperature that allows the paint linking curing process to proceed in less than 20 seconds, preventing tempering or annealing from occurring in the can, and a control system is configured to adjust the output of the broadband infrared source using sensor information to ensure that curing maintains a consistent temperature and result. [Brief explanation of the drawing]

[0081] [Figure 1] This figure shows an exemplary can being cured using the present invention. [Figure 2] This figure shows an example of a system according to the present invention. [Figure 3] This figure shows another example of the system according to the present invention. [Figure 4] This figure shows another example of the system according to the present invention. [Figure 5] This figure shows another example of the system according to the present invention. [Figure 6] This flowchart illustrates an exemplary conventional method for forming a can. [Figure 7] This figure shows another example of the system according to the present invention. [Figure 8] This figure shows another example of the system according to the present invention. [Figure 9] This figure shows another example of the system according to the present invention. [Figure 10] This figure shows another example of the system according to the present invention. [Figure 11] This figure shows another example of the system according to the present invention. [Figure 12] This figure shows another example of the system according to the present invention. [Figure 13] This figure shows another view of the system according to the present invention shown in Figure 12. [Figure 14] This figure shows another example of the system according to the present invention. [Modes for carrying out the invention]

[0082] The embodiments described herein teach a completely new concept for heating a can, including the following: 1) Curing of the inner coating of food cans, beverage cans, and other types of cans. 2) Drying the cans after washing, 3) Curing the ink or paint on the outside of the can. Many of the embodiments described herein are suitable for replacing all or some of the conventional ovens used in can making, including the gas drying ovens, deco ovens, and / or inside bake ovens (IBOs) (and / or base coater ovens, in some cases) described above in relation to known techniques for forming cans. That is, all or selected functions described herein can be performed in relation to curing the paint inside the can, drying the can, or curing the ink or paint outside the can, or in relation to various combinations of these functions.

[0083] According to the embodiments described herein, improved performance efficiency can be achieved in various ways. For example, curing and drying times can be advantageously reduced. For example, applying the embodiments described herein to cure paint inside a can at a curing station allows the can to be heated to a critical temperature, enabling the linking (or cross-linking) curing process to proceed in, for example, less than 20 seconds (or, as a further example, less than 10 seconds, less than 5 seconds, or less than 2 seconds). For example, applying the embodiments described herein to cure ink or paint on the outside of a can at a curing station allows the ink or paint in each can to be cured in, for example, less than 20 seconds (or, as a further example, less than 15 seconds, less than 10 seconds, or less than 5 seconds). For example, applying the embodiments described herein to drying cans allows each can to be dried sequentially, or each can in a large quantity of cans or a group of cans, to be dried in, for example, less than 20 seconds at a drying station. Performing each drying and / or curing function for less than 20 seconds prevents tempering, annealing, or weakening of the can. Furthermore, in embodiments where all three or two functions are performed, and the drying or curing function is performed for less than 20 seconds at each of the irradiation station, drying station, or curing station, tempering, annealing, or weakening of the can is prevented. In at least one alternative, the drying function (after washing) may be performed for 60 seconds or less (or, as a further example, less than 50 seconds, less than 40 seconds, less than 30 seconds, or less than 20 seconds). Here, tempering, annealing, or weakening of the can is still prevented.

[0084] First, the internal curing of the can will be explained with reference to Figures 1-8. The techniques for drying after washing and curing the ink will be explained in general with reference to Figures 9-14 (and other figures as needed).

[0085] In this regard, one preferred implementation would consider using narrowband semiconductor-generated infrared energy focused on the inside of the cans to influence very fast curing results inside a can curing station. Consider using focused, high-power radiant energy that directly affects the paint and sidewalls on the inside of the can, rapidly transferring energy to both the paint material and the can walls, reflecting it back to the paint material and re-radiating it. This high-power radiant narrowband energy is introduced directly into individual cans and bounces at the speed of light within the cans until almost all of the energy is absorbed by the paint and aluminum substrate.

[0086] While it is possible to influence the interior of a can with the same magnitude of direct radiant energy using a broadband light source, for many reasons, a narrowband light source is preferred and perhaps the most ideal solution. Broadband light sources such as quartz lamps can be used, but they do not offer many advantages, and the implementation is not as beneficial. However, it is possible to implement and practice the embodiments described herein using broadband light sources. For example, quartz lamps, high-intensity discharge lamps, or arc lamps can be used. They tend to have wavelength output bandwidths that are short enough to be focused with ordinary glass optics. Ordinary optical glass begins to lose its effectiveness, but beyond wavelengths of about 2.7 microns, most broadband light sources and the upper limits of resistive heating sources can not penetrate the focusing optics, sometimes overheating the optics to extremely high temperatures. Instead of focusing the thermophoton energy with a refractive optics, a reflective optical configuration can be used. For example, a nearly conical reflector or an ellipsoidal circularly symmetric mirror can be used to focus infrared energy into the inside of the upper side wall of a can or container. This is the optimal region for energy to strike the inside of the can because internal reflections from there disperse the energy away from that preferred starting region. At certain production speeds working with curing paint on cans, various broadband light sources almost certainly need to be kept on continuously, as they cannot be switched on and off at the speed required for this application. While this is possible, equipping such a system with switching electronics to handle, for example, the 2,000-3,000 watt quartz bulbs required at each curing station would be prohibitively expensive. The cans need to be heated to the temperature required to achieve the linking curing action, but with great care must be taken not to heat them so much that the aluminum body of the can is annealed. It would be highly desirable to closely monitor the can temperature and electronically control the output of the broadband devices.One of the fundamental advantages of the embodiments described herein is that cans with strength equivalent to those obtained from conventional processes, which are now almost universally used in the global canning industry, can be manufactured using less weight aluminum, while eliminating the weakening effect on aluminum. Another consideration for broadband light sources is that they inherently have a shorter lifespan than semiconductor devices used in narrowband light sources. For example, quartz lamps have a shorter lifespan, and their photon output continues to decrease as they wear down. Electronic equipment must regulate the power to continuously compensate for the decrease in output. Monitoring sensors can be used in conjunction with narrowband devices to provide feedback on the can temperature, i.e., the integrity of curing.

[0087] Many narrowband light sources can be used, including high-power lasers, various semiconductor-based irradiators, laser diodes, surface-emitting laser diodes including edge-emitter laser diodes, VCSEL laser diodes, SE-DFB laser diodes, laser arrays, and even light-emitting diodes (LEDs) such as high-power LED arrays. Multiple device arrays (for example, more than 10 devices per array) can be used to generate output power (for example, more than 100 watts). The embodiments described herein can be implemented with other modalities, such as high-power laser diode arrays, as they are easy to implement and provide desirable implementation effects. Furthermore, various examples and implementations of narrowband light sources or arrays, including semiconductor narrowband infrared sources or arrays such as laser diode arrays, are described, for example, in U.S. Application No. 11 / 003,679 (currently U.S. Patent No. 7,425,296) filed on 3 December 2004, U.S. Application No. 12 / 718,899 (currently U.S. Publication No. 2011 / 0002677A1) filed on 5 March 2010, and U.S. Application No. 12 / 718,919 (currently U.S. Patent No. 9,282,851) filed on 5 March 2010—all of which are incorporated herein by reference.

[0088] Narrowband energy is also advantageous for better optical precision because nearly the same wavelengths can be focused to sufficiently similar points, which is not possible with broadband sources. Some implementations use optical coatings such as anti-reflective coatings, which can be optimized very efficiently only at specific wavelengths or within a narrow range of wavelengths used.

[0089] Because laser diode arrays can be digitally switched on and off instantaneously, they are advantageous for a wide variety of possible implementations of the embodiments described herein. They can also be configured to be optically processed in many convenient ways to facilitate directing the appropriate energy to the required precise area of ​​the can in order to effectively carry out high-speed curing. This disclosure teaches a number of optical implementations and a number of mechanical implementations of can handling, which are possible examples, depending on the exact application and preferences of the implementer of the embodiments described herein.

[0090] When the embodiments described herein are effectively implemented, it should be possible to influence the system curing the paint inside the can in as little as one second. With sufficient power from the radiation source, curing may even be possible in less than one second if the paint is formulated to initiate the linking process quickly enough. It should be understood that reducing the curing time compared to conventional methods improves overall efficiency, benefits, and results. In particular, if the curing time is reduced to, for example, less than one minute, the improvement increases substantially. Further examples show that curing times of less than 30 seconds, less than 20 seconds, less than 10 seconds, less than 5 seconds, less than 2 seconds, and (as above) less than one second result in even greater improvements. If curing is fast enough, for example, less than 20 seconds in at least one embodiment, or, as a further example, less than 30 seconds in at least one other embodiment, can annealing is prevented. Similarly, the shorter the curing time (e.g., less than 10 seconds, less than 5 seconds, or less than one second), the easier it is to avoid annealing. Preventing the annealing effect eliminates the need to over-reinforce the cans to maintain sufficient strength after the curing process. This is a significant advantage for can manufacturers, as approximately 70% of the component and manufacturing costs of a standard can are the cost of the aluminum material used in its manufacture. Not having to over-reinforce the cans by 8-10% could result in substantial material savings, and therefore very significant cost savings. Until now, there has been no way to prevent can over-spec by performing high-speed curing in manufacturing. This is a completely new idea, as previous thinking made it impossible to cure at such rapid speeds, forcing manufacturers to over-spec the cans to always maintain sufficient strength. Historically, cans have been cured in aggregate transport. In contrast, the embodiments described herein introduce high-speed narrow-band curing of each individual can.

[0091] It is useful to outline the many advantages that arise from a proper implementation of the embodiments described herein. Reducing the amount of material is a major advantage in can manufacturing. Savings can also be achieved by using lightly alloyed aluminum instead of reducing the amount of material, as it is available at a lower cost than the more highly alloyed aluminum currently available. A further advantage of the embodiments described herein is that the width of the aluminum coil stock can be reduced. A shorter cut edge length results in a smaller diameter of the drawn cup. The reduced width means lower costs and improved reliability of the feed and coil processing equipment. This also means that narrower beds, double-action stamping presses, and smaller, lighter, and faster press tools can be purchased and implemented. A narrower press bed means increased machine rigidity and less moving mass, resulting in longer press and tool life. Cupper tooling, which produces smaller diameter cups, has lower initial costs and cheaper replacement tooling components. This is because the diameter involved is smaller and less tool steel is involved. Another advantage is that the embodiments described herein utilize a digital narrowband curing system that facilitates, for example, changing and precisely adjusting curing parameters to improve or optimize the level and overall curing process. A further advantage is that this adjustment can be performed dynamically to fully correspond to the selected production rate and improve or optimize energy savings. A closed-loop process can also be developed to verify the accuracy of curing and correct any under-curing or over-curing that may occur. Furthermore, the amount of curing energy can be optimized by verifying curing in real time using machine vision inspection, laser scanning, etc. This can be used to save even more energy by not injecting too much energy into the can beyond the number of joules of energy truly required for proper curing.A further advantage is that the embodiments described herein, by incorporating additives into the paint that allow for more readily and optimally absorption at selected wavelengths in some embodiments, pave the way for lower energy curing and potentially higher throughput speeds. The embodiments described herein have the further advantage of promoting significant energy savings. Yet another advantage is the elimination or near-elimination of hydrocarbons or fossil fuels in the curing process. Yet another advantage arises from the fact that the cans cure uniformly within themselves compared to other ambient cans. Yet another advantage is that the production line can be stopped and started instantly with minimal adverse effects. A similar advantage is the elimination of preheating. Conventionally, preheating was required before starting the production line, whether it was a cold start or a warm start after a shutdown. A further related advantage is the elimination of the need to clean up the oven and discard the cans as a result of unplanned shutdowns, power outages, etc. Other quality advantages arise from the ability to stop the line more easily without causing harmful consequences. The practice of stopping the line, which is avoided by users of the current technology, can cause such harmful consequences. Eliminating unnecessary excess heat transfer to the plant around the IBO oven yields further advantages. This reduces the need for extra cooling or air conditioning in many environments. Further advantages include reducing or eliminating the use of hydrocarbon fuels. Yet another advantage of the embodiment described here is the ability to switch very quickly and completely from one type of canister to another under programmable control. Yet another advantage arises from the fact that individual series curing lanes can be serviced independently, allowing a portion of the curing section of the line to be serviced while the rest of the line continues to operate. This results in the further advantage of greater continuous operation, eliminating the need for periodic shutdowns for oven maintenance. Ultimately, this should improve production throughput and reduce downtime.

[0092] Now, referring to the drawings, the narrowband, high-speed in-can curing technique described in relation to the embodiments described herein can be carried out in many different ways. The various ways of carrying out the exemplary embodiments described herein mainly concern two common areas: firstly, how the system is arranged so that the can is introduced into and removed from a narrowband irradiation source; and secondly, how the narrowband irradiation is generated and directed specifically to the required area inside the can.

[0093] According to the embodiments described herein, a two-piece beverage can with a cured internal coating is typically known in the industry and has the sections described below, as shown in Figure 1. While cans of other shapes and configurations, such as cans with tapered walls, can also be cured, most two-piece cans remain in the configuration detailed herein for teaching purposes relating to the practices of the embodiments described herein. In this regard, the can (22) has a moat (26) and a straight vertical wall (23) extending from the heel region (25) to the top of the can. The top of the neckless, straight-walled can (22) is typically called a trimmed edge or trim edge (21). The internal coating and subsequent curing operations are typically performed on the neckless, straight-walled can (22). It is later necked and flanged in the region near the trim edge in a necker / flanger machine operation. At the bottom of the can (22), there is a region formed from the bottom of the wall (23), called the heel (25), which transitions into the moat region (26) and finally into the arched dome region (24) in the center of the bottom of the can (22). These various sections of the can (22) are designed and thoroughly tested to withstand the pressure required for soft drink and beer containers. This pressure range is generally in the range of 90 to 110 PSI. The base metal (28) from which the entire body of the can (22) is manufactured is most typically made from aluminum alloy #3,004. This alloy is selected and standardized in most industries due to its combination of strength, formability, and resilience, depending on the can-making process and application. Admittedly, this alloy is more expensive than straight aluminum material. If it were easier to manufacture fully functional cans from low-alloy materials, it would save money for manufacturers.

[0094] The outer surface of the can (22) is typically covered or printed with a layer (29) of paint or ink, as shown in the figure. Current industry practice is to coat the entire inner surface of the can (22) with a layer of epoxy material such as layer (27), which is then baked and properly cured. The industry specification for properly cured paint is well known within the industry and is part of the manufacturer's specification. Of course, it is completely unacceptable for there to be areas on the inside of the can that are not completely covered or properly cured. The can manufacturing industry is always concerned with ensuring that all paint is properly cured and that there are no void areas, which are uncured areas of epoxy, in the final product. Non-epoxy paints have been experimented with but have not been widely deployed. Where other types of paints or partial coatings require heating or heat curing, the embodiments described herein are also very effective for them. The same applies to new specification paints that reduce or eliminate BPA in heat-cured paints.

[0095] There are two main areas requiring design attention, but the first challenge encountered by anyone implementing the embodiments described herein is how to generate a powerful narrowband irradiation. The designer's initial impulse is to construct something that irradiates in multiple directions, if not 360 degrees, and can be inserted into a can. While this is possible, most of the technologies available for generating high-power narrowband energy are considerably larger in size than can be inserted into an unnecked beverage can from the top. Technological advancements will certainly make this more practical as narrowband energy devices become smaller, allowing more power to be generated more efficiently in smaller packages. Regardless of the size of the energy generating device, the problem with "inserting into a can" technology is that it involves more moving parts and mechanisms. The insertion / retraction needs to operate at 200-400 strokes or insertions per minute, and that required speed may increase in the future. This assumes that the production flow of the entire can-making line is divided into 6-8 curing lanes, each operating at a throughput rate of 200-400 cans per minute. In this regard, for example, a typical production rate could be over 300 cans per minute. While the concept of inserting and withdrawing the irradiation source from the can is still a viable implementation technique, inserting and withdrawing the irradiation source at this high speed would require more mechanisms. This would be more complex than a non-articulated structure that does not enter through the opening of the can body, and therefore would likely require more maintenance.

[0096] Instead of inserting and retracting actual light sources for narrowband illumination, the insertable and retractable portion can be an optical system or some form of light guide to direct the narrowband illumination generated outside the can to the appropriate location inside the can. This can take the form of a fiber optic light guide configured to collect energy from one or more narrowband sources and deliver it to the can. For example, if a single very high-power laser is used to provide narrowband radiant energy, the fiber optic light guide can be coupled to a location safely away from the rigors, vibrations, and contaminants of the actual curing station. To generate an output pattern that properly illuminates the paint inside the can, the correct lensing or diffusion effect would need to be designed at the exit end of the fiber optic light guide.

[0097] The light guide can also take the form of a lens configuration (see Figure 3). This is positioned to collect narrowband energy near the light source (32) and project it through an objective lens configuration (38) and mirror assembly (34), which are at the exact right focal length when the articulating mechanism (33) is fully inserted into the illumination position inside the can (22). The photonic energy (30) travels down the tube (35) and is directed to the output of the objective lens (38) inside the can (22), and, optionally with an additional diffuser (37), can directly illuminate the paint (27) inside the can. Those skilled in the art in designing high-energy lens systems and optics can construct many different permutations of lens-type and optical-guided approaches. The vertical insertion and retraction mechanism (33) ideally has a containment reflection plate arrangement (36) that keeps the photonic energy inside the can by reflecting the photonic energy back into the can. Furthermore, ensuring that all irradiation reaches the inside of the can makes the placement safer. All components and mechanisms must be designed to withstand the demanding task of rapidly inserting into and pulling out of the can in order to meet the requirements of mass production. While this methodology may prove to be an excellent way to irradiate the inside of the can with a uniform irradiation pattern, it is costly to implement due to the significant requirements in terms of joint mechanisms and engineering. It has the clear advantage of providing a very direct way to project narrowband irradiation onto the paint-coated surface for excellent results. It has the disadvantage of placing an obstacle (35) in the can that blocks some of the reflected energy (39) that needs to continue hitting the paint-coated surface until the energy is depleted. The (35) itself acts as a reflector, but some of the energy (30) that would be lost during reflection off an uncoated surface is wasted. It also generates considerable heat on the optical assemblies (35) and (34), which must be dealt with and removed.

[0098] Another technique for providing irradiation energy to the inside of the can (22) is shown in Figure 2. This has a design concept in which there are no components that would break the plane of the trimmed edge (21) by protruding into the inside of the can. The irradiation mechanism is assumed to not need to have articulated movement in and out of the can, and can be fixed in some way slightly above the can, and still be able to provide sufficient and well-distributed irradiation inside the can. In this regard, an optical system can be incorporated into and / or used with the irradiation system. A well-designed optical irradiation system can, in at least some embodiments, focus a relatively high percentage, for example more than 90% or more than 95%, of the light energy coming out of the optical configuration directly and uniformly into the inside of the can for curing purposes. Aluminum is highly reflective to these infrared wavelengths, and since the can is cylindrical, a lot of internal reflection is certainly expected. In most implementations, it should be noted that the design should be such that randomly reflected energy coming out from the top of the can opening is reflected back into the can, and the internal reflection process continues until the energy is exhausted. Because infrared light energy travels at the speed of light, many reflections occur within an exposure time of just a few seconds, enabling rapid curing.

[0099] This configuration relies on the fact that aluminum reflects highly not only visible and near-infrared light but also short-wave infrared wavelengths. If the bottom plane of the narrowband irradiation assembly is located, for example, about 0.030 to 0.045 inches away from the trimmed top edge of the can (21), this is close enough that excessive energy loss does not occur through the gap, and close enough that energy transfer occurs at the angle necessary to efficiently cure the paint by bouncing energy around the inside of the can. The cone or conical surface (64) must be close enough to interact with the interior geometry of the can so that most of the energy reflected out from the top opening of the can is returned to the can. The conical surface can be formed from a variety of different materials, including copper, aluminum, gold-plated metals, silver-plated metals, and / or highly reflective nanostructured materials.

[0100] The embodiment shown in Figure 2 can also be modified. In this regard, referring to Figure 7, in most embodiments, the reflective cone (64), or whatever shape is selected, needs to be positioned accordingly to provide the most optimal ventilation of water vapor from the can. The louvers (74) need to be shaped to be reflectors facing the inside of the can, but there is space between the louvers to provide vacuum air flow through the vacuum port or vent pipe 75. A well-designed airflow system needs to not only push air into the can but also draw vapor-laden air out of the can through the vents provided in the louvers (74) or reflective cone.

[0101] For example, if designed with a conical (64) internal shape with a 90-degree apex angle (69), it acts as a multi-angle reflector that is excellent at reflecting narrowband energy back to the can for further curing. Depending on the selected wavelength, the energy may bounce hundreds or even thousands of times inside the can until all the energy is absorbed by the paint (27) or the aluminum (28) of the substrate.

[0102] The primary purpose of the optical arrangement shown in Figure 2 (or Figure 7) is to inject photon energy into the can (22) as shown. In one example, narrowband photon emission energy is generated by the array (51) at the top in Figure 2. One or more arrays (51) can have any number of laser diodes connected to a suitable power supply. The array designer can use combinations of series and / or parallel connections of the laser diode devices to achieve the desired current and voltage input settings to fit the system under design. This determines the current capacity and voltage required for the power supply. By selecting the appropriate combination, the power supply specifications can be optimized. The laser diodes can be of edge-emitting or surface-emitting type design. Surface-emitting designs offer significant advantages in robustness, as they have a much larger effective aperture and are less susceptible to damage from contaminants. Conventional edge-emitting lasers are almost always coupled to fiber optic light guides, which provide a better way to deliver narrowband energy to an optical train without exposing the aperture to fragile elements in challenging environments or contaminants that could cause catastrophic aperture failure. Due to the additional costs and assembly complexity associated with fiber coupling to the device, conventional edge-emitting laser diodes, while potentially a viable solution for implementing the embodiments described herein, are less desirable and far more expensive than other solutions. Surface-emitting laser diodes, on the other hand, often do not require fiber coupling. They can typically be configured to directly illuminate an optical configuration that directs the narrowband output directly into the can. While this arrangement may, in some cases, be more vulnerable due to its proximity to the curing location, the elimination of fiber coupling can significantly reduce costs and increase the overall reliability of the configuration. Regardless of the type of device chosen for the application, the device must be mounted in a housing (55) so that its optical output is directed towards a focusing lens (56).In at least one embodiment, the housing can be configured and implemented in various ways to prevent stray infrared energy from leaking out of the housing, except through a pinhole element or an aperture element of appropriate size (described later). The output of a laser diode diverges in two directions, a leading axis and a lagging axis, or in a single direction. In the case of an SE-DFB, the output is columnar in one direction and slowly diverges in the other. In an SE-DFB, the lagging axis is considered cylindrical, and the leading axis typically diverges at 7-10 degrees. When a VCSEL is used as a narrowband photon energy generating device, it has a conical output pattern. Regardless of the type of laser diode chosen, multiple devices must be packaged in an array to ensure sufficient total output power. SE-DFBs, VCELs, and other surface-emitting devices can be packaged on a cooled circuit board in an X × Y or other pattern, but much of the energy is directed perpendicular to the circuit board.

[0103] The array may certainly be of various sizes to carry out the embodiments described herein. In at least some embodiments, arrays for in-can curing with total outputs ranging from 250 watts to over 500 watts can be constructed and used. For example, a 500-watt array could consist of 50 surface-emitting laser diodes, each capable of generating 10 watts of optically narrowband near-infrared output. Since this may not be sufficient optical output to perform curing of the paint in the can within a given time, designers may use multiple identical arrays to achieve an optimal configuration. In one test, it was shown that a single 300-watt laser diode array could adequately cure an extremely thick layer of internal coating in less than 10-15 seconds without meticulous attention to an optimized optical arrangement. In an example of a proper optical configuration, such as the example shown in Figure 2, curing can be significantly accelerated by precisely distributing the photon energy where needed to improve uniformity. This optical configuration reduces the waste of photon energy and significantly shortens the curing time. By combining arrays of the appropriate number and design, improved (e.g., optimized) production technology configurations can allow epoxy paint in individual cans to be cured very efficiently in less than one second. It should be understood that optical configurations can be designed or tuned, in at least some embodiments, to precisely deposit a desired amount of energy at a desired location inside the can. For example, an optical configuration can be implemented to precisely deposit more energy at the top of the inner surface of the can's sidewall and gradually decrease the energy downwards along the can's sidewall. Various optical elements (e.g., refraction, reflection, nonlinear, aspherical, or other elements) can be used to achieve these purposes and other purposes that suit the needs of a particular configuration.

[0104] In such improved or optimized configurations, referring again to Figure 2 (and Figure 7), an optical system or microlens array (52) is selected to generate columnar energy (54) directed parallel to the central optical axis of the system. Once the columnar energy is generated and directed towards the focusing lens (56), the output energy (57) converges toward the focal point within the pinhole (65), where the light energy intersects within the pinhole (65), emitting divergent rays (58) toward the paint on the inside of the can (22). The photon energy first passes through the layer of paint (27) and, upon reaching the inner wall of the can (28), is reflected by the inner wall of the can (28), and the energy returns again through the layer of paint (27). As shown, for example, (59), the photon energy is processed through the paint (27), bounces off the wall (28), is processed through the paint (27) and returns until all the energy is given to the paint and the can wall. Some of these rebounds strike a reflective conical surface (64), bounce back into the can, and continue the process. The conical surface (64) must be manufactured or coated with a highly reflective material. It may be copper, silver, gold, or something that reflects the specific wavelength of infrared light being used as highly as possible. The pinholes (65) & (71) are located on the plate (62). This plate is designed to be replaceable, making maintenance easy to keep the pinhole area clean and sharp. While virtually all focused photon energy passes through the pinhole without leaving any energy in the pinhole plate (62), the size of the pinhole (e.g., 3 mm) and the shape of the sidewalls must be the smallest possible for the optical configuration to accommodate, so as not to result in unnecessarily large apertures in the plate (62) and cone (64). However, it should be understood that an appropriately sized aperture can be used as or in place of the pinhole (65). In this regard, pinholes such as (65) can be readily implemented for systems according to the embodiments described herein that require more precise focusing of irradiation into the interior of the can. However, such configurations (which may generate more heat or increase implementation costs) are not necessary for all configurations.Therefore, to achieve the desired result, any suitable aperture of any size can be implemented, for example, an aperture with a diameter smaller than the opening at the top of the can. In this regard, such an aperture may be, for example, less than 2 inches, or another dimension depending on the size of the can. The reflective structure (64), which can be formed into the optimal geometric shape for reflecting energy back to the can, is made to be easily replaceable so as to provide a clean reflective surface. It should be designed to be replaced quickly and easily on a regular basis as needed, and to be replaceable with minimal tools. The angle of the reflective cone insert (64) should be carefully modeled to reflect the maximum amount of energy back to the can, taking into account the specific shape of the can's geometry. The housing (55) should be made of a material that can handle the scattered reflection of the infrared radiation it contains. It is preferable to design cooling holes (61) around the entire housing so as to allow water or coolant to circulate within the housing to keep it constantly cool. This is necessary to keep the semiconductor device array (51) at a comfortable operating temperature so as not to attempt to operate in an ambient environment that is too warm. The laser diode array (51) should also be cooled in some way. These can be cooled by a refrigerant circulation system through the actual array, or by deionized water. In the most desirable implementation, it may be the circulation of plain water through the array. If the device is very efficient, as may be the case in the future, gaseous or liquid coolants may not be necessary, and air cooling by a heatsink and fan may be sufficient to keep the device within a comfortable operating temperature range. The housing (55) may have further cooling equipment so that any components mounted therein, such as optical components or laser diode arrays, do not feel too hot. In this case as well, the cooling of the housing (66) may be a recirculating water jacket or a forced air cooling system. It should also be understood that the bottom surface (67) is configured in at least one form to control the reflection of energy escaping from the inside of the can (22).To achieve this objective, various configurations and / or techniques can be implemented, but as shown in the figure, the surface (67) is provided with grooves, such as deep grooves, to control the escaped energy. Regardless of the shape of the bottom surface (67), the front and rear flush mating surfaces of the housing (55) must be designed and assembled so that the incident surface (73) is at the same level as the furthest point reached by the bottom surface (67) of the housing (55). Also, the exit surface (72) must be at the same level as, or slightly higher than, the furthest point reached by the bottom surface (67) of the housing (55) so that the upper trim edge surface of the can (22) does not encounter any bulges.

[0105] Using these various techniques, it is possible to use broadband infrared irradiation sources such as quartz lamps or high-energy discharge lamps. However, these are more difficult to concentrate energy precisely. They are not energy efficient in that they produce the most efficient wavelengths that match the paint for the best and fastest curing. They are inherently extremely hot due to the way they generate their basic output energy. This requires more engineering to keep everything cool and prevent the can from overheating completely. If the can overheats, even for a short time, it can anneal or temper. These broadband infrared sources do not allow for very precise control of the amount of heat delivered to the can, and the output needs to be adjusted as a function of throughput speed. However, they cannot be switched on / off as quickly and precisely as semiconductor-based irradiation, but this can be adjusted with careful engineering. For example, as mentioned above, broadband electric infrared components such as quartz lamps, high-intensity discharge lamps, and arc lamps can be used. Here again, a reflective optical configuration can be used instead of concentrating thermal photon energy with a refractive optical configuration. For example, infrared energy can be focused to the inside of the upper sidewall of a can or container using a well-designed reflector arrangement, such as a nearly conical reflector or an elliptical circularly symmetrical mirror. This is the optimal region for the energy to strike the inside of the can because internal reflection from there disperses the energy from its preferred starting region. In this regard, the configuration shown in Figure 3 (and also the configuration shown in Figure 2) can be appropriately modified to implement a broadband embodiment, where the radiation source is implemented as a broadband source, and the optical elements are implemented using reflective elements rather than refractive elements, and they are positioned to direct or orient the radiation to the upper sidewall on the inner surface of the can.

[0106] Referring here to Figure 8, a broadband infrared system 200 is typically shown. System 200, for use in manufacturing cans in an internal coating and curing process in which paint is sprayed onto the inner surface of the cans, includes a can handling system 205 (not shown in detail) configured to move the production cans sequentially to at least one curing zone. Furthermore, system 200 includes a broadband infrared source, such as a broadband infrared source 230 including a quartz lamp 220, which is configured to individually electrically heat the inner surface of each can 22 (shown in cross-section) as it moves into the curing zone using an optical element 240 positioned to direct the irradiation toward the upper sidewall of the inner surface of the can (e.g., typically shown in 260), so that the paint on the inner surface of each can in the series of production cans reaches a critical temperature for the paint linking curing process to proceed in less than 20 seconds, preventing the cans from tempering or annealing. The system also includes a control system 210 (connected using link 250 – which can take various forms, only representative ones shown here) configured to adjust the output of a broadband infrared source using sensor information (not shown) to maintain a consistent curing temperature and result. The form of such a system 200 can be modified as shown, but the optical elements can take the form of a well-designed reflector arrangement, generally a conical reflector, or an elliptical circularly symmetric mirror, used to focus infrared energy inside the upper side wall of the can or container 22, as described in the example above. In at least one form, such optical elements are at least slightly smaller in size than the diameter of the container or the opening of the container, such as the container 22, in order to allow for proper transfer of energy to the can and proper maintenance of that energy inside the can for curing purposes.

[0107] However, as described herein, precise digital control and accurate energy control work to the advantage of semiconductor solutions. Semiconductor-based irradiation configurations should have a much longer lifespan and much more stable output throughout their service life. While broadband light sources have a lifespan of several thousand hours, their output continuously degrades during that time, requiring careful adjustment to achieve stable curing results. Since not all broadband light sources wear out at the same rate, ensuring that the irradiation output of each lamp is sufficient to ensure proper curing is an engineering challenge and a chronic maintenance issue.

[0108] Referring here to Figures 4 and 5, the implementations of the embodiments described herein should, in most forms, also address preferred configurations for mechanical handling of the can. There are at least four different forms of these configurations. Furthermore, although the description of Figures 4 and 5 includes references to examples of narrowband irradiation sources, it should be understood that broadband infrared sources and corresponding systems can also be used in these embodiments with appropriate modifications as needed.

[0109] Furthermore, while exemplary implementations are shown in Figures 4 and 5, implementations can take various forms. Along these lines, the methods and / or systems according to the embodiments described herein can be implemented in the manufacture of cans in an internal coating and curing process in which paint is sprayed onto the inner surface of the cans. A can handling system (e.g., including a conveyor which can take various forms) sequentially transports the cans toward at least one curing station. The cans are then individually electrically heated at at least one curing station, for example, using radiated infrared energy generated by narrowband semiconductors (e.g., generated by an array of semiconductor-based narrowband irradiators) and optical elements placed on the outside of the cans, and the paint on the inner surface of each can in a series is brought to a critical temperature in less than 20 seconds to achieve a linking curing process of the paint, which prevents tempering or annealing from occurring. This technique can reduce the amount of aluminum by, for example, 3% or more compared to conventional techniques. As curing time increases, cans tend to weaken, so to compensate for this, the cans are made thicker. However, this technology allows thinner and lighter cans to have the same sidewall axial strength, bottom inversion strength, and overall strength as thicker and heavier cans, while maintaining a shorter curing time. Furthermore, an exemplary embodiment includes an ingoing trackwork or conveyor, a second conveyor, one curing station, and a third conveyor, the ingoing trackwork or conveyor being configured to facilitate the organization or movement of individual containers so that they are aligned in a line toward the second conveyor, the second conveyor being configured as a rotating turret for loading and unloading individual containers toward at least one curing station, and at least one curing station including an optical configuration.Here, the optical configuration is such that photon energy from at least one array of surface-emitting laser diodes passes through columnar optics, is then focused through a pinhole or aperture by at least one focusing lens element, and beyond the pinhole or aperture, the photon energy diverges to illuminate the inside of the side wall of the paint-coated container. Such a pinhole or aperture is located at the apex of a reflective cone, which functions to reflect the photon energy back to the container for further curing. The paint is cured in less than 20 seconds, fast enough to prevent weakening or annealing of the aluminum constituting the container. A second conveyor carries the containers and guides them to a third conveyor configured to remove them from the second conveyor. Then, in order to continue curing sequentially, while the cured containers are transported on the third conveyor for the next container manufacturing operation, the waiting uncured cans are loaded into the available empty pockets. Furthermore, exemplary embodiments include an ingoing trackwork or conveyor, a second conveyor, a curing station, and a third conveyor, wherein the ingoing trackwork or conveyor is configured to facilitate the organization or movement of individual containers so as to align them in a line toward the second conveyor, the second conveyor is configured as a rotating turret for moving individual containers toward and toward at least one curing station, the at least one curing station includes an optical configuration, where the optical configuration includes photon energy from at least one array of surface-emitting laser diodes passing through columnar optics, then being focused and passing through a pinhole or aperture by at least one focusing lens element, and beyond the pinhole or aperture the photon energy diverges to illuminate the inside of the sidewall of the paint-coated container. Such a pinhole or aperture is located at the apex of a reflective cone, such a reflective cone functions to reflect the photon energy back to the container for further curing.The paint is cured in less than 20 seconds, fast enough to prevent weakening or annealing of the aluminum that makes up the container. A second conveyor carries the containers and guides them to a third conveyor configured to remove them from the second conveyor. Then, in order to continue serial curing, while the cured containers are being transported on the third conveyor for the next container manufacturing operation, the waiting uncured cans are loaded into the available empty pockets.

[0110] More specifically, referring again to the drawings, one example of a configuration outlined in relation to Figure 5 is a configuration involving continuous rotational motion. In this configuration, a narrowband irradiation source (and possibly a controller), optics, cooling system (such as a heat exchanger, chiller, and / or recirculation pump), and power supply (such as a DC power supply) rotate with a star wheel. The star wheel organizes the cans at the correct intervals, provides the propulsion to move the cans, and transports them to a suitable location for irradiation. A rotating union is designed within the system to provide the power, control signals, compressed air, vacuum, and / or cooling required for a continuously rotating turntable or turret. The premise here is that the narrowband irradiation array or narrowband irradiation source is configured to continuously irradiate the inside of the can through the optical configuration for the time required to deliver a sufficient number of joules of energy for complete curing. The entire irradiation system rotates appropriately with the can in synchronous motion. The irradiation of energy is turned on as the can rotates through the starting irradiation station and turned off before the can leaves the star wheel. For example, if a particular narrowband irradiation system can generate 500 joules and 850 joules are needed to precisely cure a particular can, the irradiation needs to be on for 1.7 seconds along the arc traced by the rotating star wheel. The on-start time and on-duration of the irradiation can be fixed or, more ideally, programmable parameters. The percentage of time the irradiation is on (duty cycle) should be programmable in at least some form, by adjusting the intensity or pulse width. The user interface can be configured to meet the end customer's needs. The user interface can range from simple screen entries on the programmable controller's display to complex PC-driven user interfaces with user-friendly graphics showing on / off timing, duration, and intensity. The intensity curve as a function of time or turntable position can also be programmable or graphically configurable.The system controller can communicate with portable devices such as tablets, smartphones, and smartwatches, making it very convenient to monitor the settings, speed, and functions of the curing system. The diameter and RPM (rotation speed) of the star wheel must be set so that the irradiation provides a sufficient dwell period for proper curing to be performed. This configuration of the embodiment described herein is described in more detail below.

[0111] This narrowband radiation curing system is highly programmable and flexible, allowing it to be connected to other related means. A downstream inspection system (97) can inspect the cans being shipped (89) to verify that the coating covers the entire inside of the can and that it is fully and properly cured. This inspection system can use either a visible light grayscale camera or a color camera, or an infrared camera at the exit of the curing system, or both types. The inspection system can ultimately attempt to determine whether there is any exposed, uncoated metal or uncured paint present. If the inspection system (97) cannot verify that the paint is not properly cured, the system closes the loop and gradually increases the number of joules of energy applied to the different cans from each station to verify that they are properly cured. The system can correlate information on which cans were cured by which curing system (91). If the curing of cans from individual curing stations is insufficient, the system can correct and increase the curing energy from that particular curing station. A similar process modification by closing the loop that returns from the inspection station to a specific curing station can be achieved in any configuration capable of implementing the embodiments described herein.

[0112] The system in Figure 5 works as follows: Sprayed but not yet cured cans (82) arrive by a conveyor, trackwork, or similar mechanism, or a system configured to organize or facilitate the movement of individual containers in a line toward another conveyor or device, for example. Such a conveyor can be any form of conveyor, including a vacuum conveyor, or it can simply be trackwork that guides the cans while pushing them with air or gravity. Schematically shown is a vacuum belt conveyor (80) which also has guide trackwork (81) along both sides of the row of cans. The row of cans (82) is pushed forward so that a slight pressure is applied to the holdout plate (87) when the next can to be loaded sits on the dead plate (96). As the turntable or turret (84) rotates, the cans continue to push against the holdout plate (87) until the next empty pocket (86) arrives and can be pushed into that pocket. When a can is pushed into the pocket (86), it is sucked in with the help of vacuum from the rear of the nest hold-out plate (87), which is the part closest to the center of the turntable. The shape of the hold-out / nest plate must be carefully designed so that the can slides in smoothly when the pocket is open and ready for use, without the can being dented or deformed. It is also necessary to determine a consistent position for the can and hold it firmly in that consistent position during curing. As the turntable (84) continues to rotate, the can moves to the nest position (86) and, as it passes the loading station, a signal is sent to start (turn on) the energy irradiation. The control system turns on the energy irradiation at a speed that the irradiation device can handle without causing harmful effects, but not so slow that time that could be effectively used for curing is wasted. The control system and power supply (95) corresponding to each irradiation station power up and the array of irradiation devices (85) is activated. The can should be positioned centered under the irradiation optics (91) throughout the time it is being rotated by the turntable.The optical system (91), array (85), and power supply and control system (95) rotate together with the turntable (84), and their relative positions are maintained throughout the entire rotation process. Encoders (93) continuously feed back information on rotational position and rotational speed to a central control system (99) via cables (98). The central control system (99) feeds back relevant information to local controls (95) that each station needs to properly operate each irradiation station (91) at the appropriate timing and output level. Each control system (95) monitors the cooling status of each station and feeds back this information to the central control system (99) via interconnects (98), facilitating the smooth and complete monitoring and control of all stations.

[0113] As the cured cans (89) approach the unloading station, they gradually come into contact with the stripper arm (90), which gently pushes them out of the station onto an already moving vacuum conveyor belt (88). The cured cans (89) continue along the vacuum conveyor (88), passing under the inspection station (97) on their exit path from the curing system. Alternatively, a trackwork system could be used to move the cans out of the curing system using gravity or a large volume of low-pressure air.

[0114] Another viable configuration of the embodiments described herein is somewhat similar in that it uses continuous rotational or linear motion, but uses a fixed-position illumination system that energizes the can with a strobe as it passes through the correct position. This configuration requires very powerful and very short pulses of illumination energy that must be delivered with precise timing. The duration of such high-speed strobe pulses depends on the exact implementation details and the throughput speed of the material handling, but in most cases, pulses of less than 500 milliseconds are required. However, in some high-speed applications, it can be as short as 300 microseconds. It is also possible to over-pulse with a pulse array of narrowband infrared semiconductors, which can yield very high output in very short times. The concept here is that if the normal electrical supply current rating of the array is perhaps x, then a higher peak output can be obtained in very short times, perhaps 10x, 15x, or 20x. For example, if 1700 joules are needed for proper irradiation, and a group of irradiation arrays can normally output 1700 joules in 1.7 seconds with a 15 ampere current input, then to generate 1700 joules in 170 milliseconds, the current can be strobed at 10 times the normal rate (150 amperes in this case). In this configuration, the overall amount of mechanism required is reduced, and there is no need to mechanically move or dynamically link the irradiation arrays. However, pulsing such high current power requires more electrical and electronic work, and the arrays must be able to withstand the impulse power and generate proportionally higher output. They need to be tested to see if they can actually be overpulsed to this extent and whether they have a usable lifespan for a particular implementation.

[0115] The strobe and overpulse configurations can be implemented in either a rotational motion configuration system or a continuous linear motion configuration system. In either configuration, allowing cans to pass sequentially in a single line under the narrowband irradiation array facilitates strobe exposure for curing. Practitioners of the embodiments described herein have always discussed the relative merits of material handling throughput speed to the power and configuration of the irradiation system. More powerful irradiation systems can irradiate in a shorter time, ostensibly in direct proportion to the power incorporated. For example, for practical purposes, a 2,000-watt array irradiates about twice as fast as a 1,000-watt array, but requires more slow-operating material handling equipment required for the 1,000-watt array, because achieving a particular throughput speed necessitates designing the system using more serial or parallel mechanisms. Whether the material handling system is a star wheel, conveyor, or otherwise, twice the speed curing can process about twice as many cans in a given time. However, to cure at twice the speed, a narrowband irradiation system requires approximately twice the power output and a larger power supply. High-power irradiation systems generally require more cooling, and everything in the system, including the optical train, must be able to handle much higher power levels. Similarly, high-speed material handling equipment presents its own challenges. Because the kinetic energy of a moving item increases with the square of its velocity, a material handling system operating at twice the speed must handle four times the inertial or kinetic energy across the entire system, including the cans being processed. As a result of all these factors, designers and implementers of the embodiments described herein must determine how many separate lanes the system should be divided into to achieve the specified throughput, and how much power the irradiation system needs to provide to cure at the speed required by the material handling system.

[0116] A typical current can manufacturing line divides the production flow into seven lanes and paints the inner surface of the cans. It is assumed that maintenance can be performed on one of these lanes in a timely manner while the other six lanes are running continuous production. According to the embodiments described herein, each curing lane can cure individual cans at a production rate of, for example, 300 cans per minute (which corresponds to 1800 cans per minute in six lanes). Everything coming out of these six active lanes is returned to collective conveyance before passing through the IBO. In the embodiments described in the present application, each lane remains separate and proceeds through the corresponding curing lane. Therefore, since each curing lane is a parallel and independent lane, it can be started and stopped independently. They maintain independence with respect to control, service, and speed optimization. Such a configuration of independent curing lanes allows any lane to be started or stopped for any reason without stopping production across the entire plant or line. Both scheduled maintenance while production is ongoing and unscheduled maintenance or clearing jams can proceed smoothly without stopping production. If electronic troubleshooting or component replacement is required, it can be done seamlessly during normal production. Next, the multiple divided curing lanes are integrated into one high-speed single-file lane so that cans can pass through to the next manufacturing step, usually a neck flanger.

[0117] Another configuration that can be implemented according to the embodiments described herein incorporates high-speed indexing rotational motion. This configuration includes a turntable or star wheel that repeats a specified arc motion, incorporating a rotational indexing configuration. Indexing technology is one of many mechanical or electromechanical considerations. Periodic indexing can be one of a number of technologies, including mechanical, pneumatic, or any number of other indexing mechanisms such as electric servos, cams, ratchets or clutches. These mechanical mechanisms are all described in detail in the literature and patent databases, and are therefore not described in detail here, although they are used in a unique way here. Commercial products require the use of very specialized tools to process cans in a high-speed irradiation curing station, but the basic mechanism can adequately meet this need.

[0118] A star wheel or turntable moves cans under a properly indexed irradiation source, moving the cans under the source, allowing them to remain there while the source is turned on and eventually turned off, then indexing the cans as they emerge from under the narrowband irradiation source and bringing them into place so that new cans can be irradiated to them. This repeated indexing cycle has the advantage of being able to accommodate any length of residence time required by the application. While it must provide any number of joules of energy required for proper curing, speed and throughput require matching a certain radiant power with the appropriate speed of the indexer to meet the overall production demands of the system.

[0119] The indexing device can accommodate the movement of a single row of cans entering and exiting a narrowband irradiation source. Alternatively, each index can be used to move multiple cans to positions below multiple irradiation sources. Thus, it is possible to optimize the system design to have a full number of irradiation sources to handle the curing task while operating the indexing turntable at a speed within a range where its mechanism is highly reliable.

[0120] Designing a servo-driven indexing system is crucial to ensure appropriate ratios for indexing pause time, indexing time, and indexing arc length. This allows for a narrowband irradiation source configuration that maximizes maximum radiation time while minimizing actual indexing time. Multiple irradiation stations are also possible, as not all irradiation needs to be performed at a single station. This technique facilitates the smooth heating of paint in cans with sequential irradiation involving several irradiation stops. Aluminum cans cool very rapidly, and a significant amount of heat can be lost, requiring subsequent stations to inject more heat to compensate. This technique is also a viable configuration for certain types of paints that require maintaining high temperatures for longer periods. Furthermore, even when long irradiation times are required, multiple repeated irradiations can be performed smoothly and in shorter times with this mechanism. With careful configuration, this can potentially improve throughput speed. In some cases, longer effective durations may be required to expel water or for other curing reasons.

[0121] Any implementation of the rotational motion configuration of the embodiments described herein can utilize gravity to assist the movement of cans along their respective various trackwork functions. When cans move along the trackwork along a path to or from a narrowband high-speed radiated curing station, the cans are likely to come into contact with each other. Steep inclines or vertical trackworks full of cans are very useful to provide gentle pressure for pushing the next can into its respective turntable transport nest. For example, in Figure 5, the trackwork function (81), whether or not it is backed by a vacuum conveyor (80), can be configured to align along either a vertical or steep angle so that the cans (82) push against each other. The gentle pushing force due to gravity can be increased or decreased by increasing the verticality or stack length with the help of peel-off guides (87), and that pushing force can gently guide the next can into the transport nest (86).

[0122] Another method of implementing the embodiments described herein is by a linear escapement configuration, as shown in Figure 4, for example. This involves two parallel conveyors, an input conveyor and an output conveyor. They are arranged parallel to each other, with space between them for escapement tracks and stations. A programmable escapement pusher is positioned along the input conveyor and configured to push the cans into the escapement tracks between the two conveyors at the appropriate time. A narrow-band irradiation system is installed above the workstation, which is located above each escapement track of the escapement workstation, allowing for irradiation for the length of time necessary for proper curing as the cans are pushed out and placed in the workstation. Once the curing time is complete, the cans are pushed out of the workstation onto the exit conveyor at the appropriate time and fit into the gaps between other cans being processed on the high-speed exit conveyor. This type of configuration allows for a large amount of parallel processing for long dwell times, while maintaining high programmability. Typically, it can be implemented at low cost and offers greater flexibility and modularity than most other configurations. However, it requires more sensing, more programming, and more can articulation. Here, we will describe the linear escapement configuration shown in Figure 4 in detail.

[0123] The linear escapement configuration functions as follows: Referring to Figure 4, the input conveyor (111) carries upright cans in a single row. The top opening of the cans faces away from the vacuum conveyor into which they are being carried. The input speed by the conveyor (111) depends on the throughput speed and handling speed, which are the balance of the entire system. The actual speed and belt position are constantly monitored by encoders (109) directly linked to the drive of conveyors (118) and (119). The encoders are connected to a computer, control system, or programmable controller. The belt position is constantly recorded, and the position of all cans entering the material handling system is monitored by input from a photocell (100). When an uncured can (112) enters the input belt, the control system determines which irradiation station the can can enter. Seven completely independent irradiation curing stations (106) are shown in Figure 4. When the programmable controller determines that a can should be brought into station 3, it alerts the diverter (114) at station 3 to provide the necessary vector force to extend its fingers at a very precise timing to angle the can and direct it toward illumination station 3. As the can approaches station 3 and strikes the fingers of the diverter (114), the fingers, in combination with the motion provided by the moving belt, generate a pushing and sliding motion. Once the can is pushed out onto the side track conveyor at station 3, it first slides over the dead plate (113) and is then picked up by the station diverter conveyor (105). The diverter conveyor continues to transport the uncured cans to their respective curing stations (106) until the center point (110) crosses the center point of the uncured cans beneath the curing stations (106). The diverter (105) continues to transport the cans toward the curing stations (106) until the photocell (120) confirms their arrival. At that moment, the diverter conveyor (105) stops moving, the irradiation station (106) is activated, and the inside of the can is irradiated. The electro-optic system may be very similar to the one shown in Figure 2.When the on-time indicates that the correct number of joules of energy has been applied to the inside of the can, the narrowband curing system (106) is switched off, and the control system knows that the can has just finished curing and is ready to be discharged. Tracking the position of all cans in the system, the control system knows how long it will take for the diversion conveyor to carry the cans to the exit conveyor (108). When the timing is correct and there is a gap between the cans (107) as shown in Figure 4, the system prepares to restart the diverter conveyor to move the cured cans into the appropriate gaps between the cans moving down the exit conveyor (108). The system can recognize and adjust the speed of the diverter conveyor (105), provided that it is equipped to facilitate the smooth positioning of the cans at moderately even intervals on the exit conveyor (108). The diverter conveyor (105) may be equipped with a belt having holes that can be vacuumed to allow cans to adhere firmly and accelerate quickly. The outlet conveyor (108) may also be equipped with vacuum holes (104) that can be vacuumed to hold cans firmly on the belt for good acceleration and control. The inlet conveyor (111) is driven by a motor (119) and a gear drive (118), and the outlet conveyor (108) is similarly driven by a motor (101) and a gear drive (102), both of which may be variable-speed motors adjustable by a control system to achieve the smoothest can engagement depending on the supported production speed. The diverter (114) must be designed so that the fingers are fast enough to deflect the cans, but do so smoothly so that the cans do not tip over or deform. However, the fingers must also retract fast enough so as not to obstruct the next approaching can. The control system must know the reaction time for extending and retracting the fingers and be able to coordinate the timing of the transport, detour, and exit of all cans on the conveyor (108).

[0124] It should be recognized that, in at least some form, many of the functions of the embodiments described herein (including, for example, the embodiments described in relation to Figures 1-14), such as the function of generating narrowband infrared energy (or broadband energy), the function of producing cans, the function of inspecting cans / coatings and / or feedback information, and the function of handling cans, are controlled by a suitable controller or control system. Such a controller or control system may take various forms depending on the particular implementation, but in at least one form it is implemented with a suitable hardware configuration and / or software routines to realize the forms and functions of the embodiments described herein. For example, such a controller or control system includes, in at least one form, at least one processor and at least one memory containing code or instructions that, when executed, cause the system's processor or other components to operate or function in a particular way. The memory can take various forms, including non-temporary computer-readable media or devices such as read-only memory (ROM), random-access memory (RAM), or other memory structures. Furthermore, such a controller or control system may be incorporated into, for example, a standalone system, a distributed system, or another or more comprehensive system.

[0125] The various form factors that enable the embodiments described in this application, as described above, are primarily for facilitating the direct narrowband irradiation of the curing portion. Depending on the factors, it may be necessary to enhance the above configuration for complete curing. One form of enhancement may include providing a preheating section through which the can passes immediately before the narrowband irradiation section. Preheating the can in this way can reduce the number of joules of energy required in the narrowband irradiation section.

[0126] Another form of enhancement may involve providing a post-blow section after narrowband irradiation. Since the majority of undried paint is liquid water, the moisture needs to be removed at some point in the curing process. Once the water that should have evaporated just before reaching the temperature for curing and cross-linking has been reached has evaporated, the vapors need to be removed from the can. To remove the vapors from the can, warm air may be needed, or it may simply be necessary to blow air onto the can. This can also be configured as a post-warming section, either in a circular or linear arrangement with trackwork guiding the can through each section.

[0127] The preheating section may be of the hot air type or the radiant type, and may be equipped with a gentle radiant preheating system, for example, with a row of quartz lamps. The reinforcement section can be varied depending on the exact installation conditions of the system, the plant configuration, and the geographical climate. Those skilled in the art will understand that not only can a narrowband curing system be configured in many different ways beyond the specific examples taught here, but the reinforcements before and after it can also take many forms.

[0128] One of the key differences between the embodiments described herein and conventional methods for curing the inside of beverage cans is that the embodiments described herein cure by direct radiant energy. Conventional IBO curing ovens heat the inside of the cans by hot air convection. IBOs heat air in some way, either by burning natural gas or by resistive electric heating. Both heat the air, and that hot air heats the cans. The belt on which the cans are placed becomes hot, so some heating occurs by conduction from the conveyor belt to the bottom of the metal cans. This is also a drawback and inefficiency of IBOs. The belt is continuously heated each time it passes through the oven, and heat is expelled from the oven. Thus, the intention of current vintage IBOs is that the majority of the can heating is done directly by convection of air.

[0129] Convection heating is generally an inefficient heat transfer process. It is a multi-stage process, and losses inherently occur between each stage. The air must first be heated, then it must be brought into contact with the can to transfer its heat to the can and the paint applied to it. The same amount of hot air hits the outside of the can as hits the inside. Of course, the hot air hitting the inside of the can hits the paint and then conductionally heats the metal. On the other hand, the hot air hitting the outside of the can should heat the metal, and then that metal should heat the paint. In a perfect world, it would be far more desirable to heat only the paint to the temperature required for cross-linking and curing. This is virtually impossible, however, because the applied paint is in close contact with the aluminum substrate that makes up the can body and is very thin, heat is transferred directly to the metal substrate. In this heating method, the metal substrate heats up as much as the paint. Also, the hot air in the oven is not perfectly uniform. Hot spots inherently exist within ovens, and because air movement varies from place to place, some cans tend to overheat while others underheat. One way to correct this tendency is to use more oven heating than is truly optimal to prevent uncured cans.

[0130] In particular, with aluminum cans, prolonged exposure to such temperatures weakens the aluminum. It is well known in the industry that, to compensate for the weakening effect that occurs after spending 2-3 minutes at high temperatures in an IBO (Integrated Burning Oven), the raw can material needs to be manufactured heavier and stronger than the final specification.

[0131] It is not entirely clear whether this weakening effect is due to tempering or annealing. Metallurgists are divided on what to call this effect. What is very clear and well known is that aluminum is definitely weakened during the process of passing through the oven. It is generally believed that 8-10% of the bottom inversion strength is lost as a direct result of passing through the oven.

[0132] Traditional annealing typically occurs at temperatures higher than those in an IBO oven and for longer periods than the cans are kept in the IBO oven. Literature reviews support this for 3004 alloys and other similar alloy families. A closer examination of the literature and at least one study indicates that, due to the extremely thin aluminum, this annealing and tempering process can occur very quickly in cans. Aluminum is an excellent thermal conductor, and at typical wall thicknesses of 3 to 4 thousandths of an inch, heat penetrates almost instantly. Aluminum cans are measured in seconds, not minutes or hours, as is the case with most items subjected to annealing.

[0133] 3004 alloy aluminum, also known as UNS A93004, has the following chemical composition in addition to base aluminum: up to 0.3% silicon, up to 0.7% iron, up to 0.25% copper, 1% to 1.5% manganese, up to 0.8% to 1.3% magnesium, up to 0.25% zinc, and other elements up to 0.05% each, totaling up to 0.15%. This alloy has several tempering variations. Examples of available standard temperings include 0 (annealed), H32, H34, H36, and H38. H indicates the degree of strain hardening, and the degree of strain hardening and stabilization is represented by H3X. A specific tempering commonly used in aluminum beverage cans is H19, which has a lower degree of strain hardening than H32 but is harder than the annealed state. H19 tempering is ideal for cold working, a critical process performed during the D&I (Drawn & Ironed) process. Tensile strength specifications vary, ranging from 26 kPSI to 41 kPSI. Yield strength also varies, from 10 kPSI for 0 tempered or annealed products to 36 kPSI for H38 tempered products.

[0134] A 8-10% decrease in can strength means a decrease in the buckle strength or bottom reversal strength that the can can maintain under pressure. It should be noted that can buckle strength does not directly correlate with yield strength or tensile strength; the precise geometry and thickness of the can are crucial factors in can strength. However, since these are well-matched and measurable both before and after curing, it is clearly the change in tensile strength and yield strength that is causing the loss of buckle strength or bottom reversal strength. This annealing / tempering effect is clearly a factor that the can manufacturing industry must address appropriately.

[0135] In the embodiments described herein, the annealing / tempering effect that occurs with IBO can be virtually eliminated. The embodiments described herein abandon the use of IBO and instead employ a high-speed narrowband infrared radiation curing technique. The cans are in a single row, and irradiation is directed to each can individually. They are cured one at a time in sequence, rather than as a group. The controllability and relative efficiency of narrowband irradiation heating allow the paint to reach the temperature for complete curing and cross-linking in just a few seconds. Because the cans are exposed to high temperatures for such a short time, there is no room for weakening effects to occur. Details and techniques for implementing this high-speed radiation curing technique are described in more detail throughout this application.

[0136] Based on the results of absorption spectral analysis, the penetration depth of a spray-coated sample can be calculated. In this application, low transmittance is practically preferable because it corresponds to the rapid absorption of IR radiation.

[0137] The formula for the penetration depth (95% absorption) is as follows: β = (3 × l) / A, where β is the penetration depth in millimeters, l is the optical path length of the experimental sample, and A is the absorbance at a specific wavelength. As an example, at a wavelength of 1930 nm with an absorption of 1.526, the penetration depth β = 3.93 mm. This means that infrared light needs to pass through 3.93 mm of paint for 95% of the incident energy to be absorbed. This is obviously impossible considering the thinness of the paint on the side wall of the can, which is 0.00254 mm. Fortunately, however, aluminum reflects IR radiation very well. This reflection process begins around the inside of the can, where the infrared light is slightly absorbed when it first passes through the spray-coated paint, reflected by the aluminum substrate beneath the paint, and passes through the paint again when it returns on that reflection. At each reflection, the light path contacts the spray-coated paint and the aluminum wall. The amount of energy absorbed by the aluminum during these slightly imperfect reflections is small, but it is useful for the curing process. This is because energy is transferred to the aluminum surface holding the sprayed compound, generating heat and further heating the compound. It should also be understood that once the aluminum is sufficiently heated, the external decoration of the can can also be cured. Since this may be desirable in some implementations, the system can be designed, configured, or adjusted to accommodate such heating and curing purposes.

[0138] For the thinnest standard coating thickness as described above, the light passes through the paint twice with each reflection, so the distance the sprayed paint travels with each reflection inside the can is 0.00508 mm. To reach the 95% absorption rate determined above, the light passes through the can 774 times, which means it has acted on the coating over a length of 3.93 mm. In a 65 mm wide can (although unrealistic, assuming perfect orthogonal reflection from wall to wall), this means the light would need to travel approximately 50 m before being completely absorbed. This may seem like a long process, but the speed of light (c = 3 × 10⁻¹⁰) 8Because m / s is extremely fast, this is actually a very fast process. It can be calculated that it takes 0.17 nanoseconds for the thinnest paint thickness of 0.1 mil and 0.03 nanoseconds for the thickest paint thickness of 0.5 mil. As this calculation shows, the time it takes for the laser diode to emit energy is actually much longer than the time it takes for the paint to absorb it.

[0139] As already explained, the current traditional method of curing paint in cans utilizes a large oven with a collective conveyor belt. The cans are heated in three consecutive sections. The oven is supplied with natural gas, and the temperature of the final section is maintained at 375-450 degrees Fahrenheit. The cans pass through this hottest section of the oven using the collective conveyor belt, with a curing time of the order of one minute. Due to the high costs associated with the oven heating procedure during initial startup, these ovens are kept on as much as possible. Keeping them on all the time is wasteful both when the line is stopped (downtime) and when can blockages occur that can stop the flow before or inside the oven.

[0140] Table 1 shows the cost increase based on reasonable assumptions and current US natural gas prices. As Table 1 shows, a considerable amount of heat must be continuously supplied to maintain a constant high temperature inside the oven. The cost of natural gas is also a significant component of the total annual operating cost. TIFF0007851863000001.tif77110

[0141] This uses the results for the thick paint thickness mentioned above to represent the worst-case scenario. Further differences between this analysis and conventional variables include: the difference between the conversion efficiency of natural gas to heat and the conversion efficiency of electricity to radiant heat, the difference between $ / MCF for natural gas and $ / kWh for electricity, and the difference between oven operating time and diode array operating time.

[0142] While a direct comparison is not possible, this difference works to the advantage of narrowband radiant electric heating. Assuming that typical line uptime (the time actually used to manufacture cans) is 89% of the total available time in a year, it is assumed that the oven actually remains active for a longer period due to the cost and time associated with cold starts. Therefore, even though the line may only be producing cans for 89% of the time, the oven is actually maintaining a high temperature for 95% of the time available in a year. On the other hand, narrowband radiant heating elements are designed to be pulsed, so they only use power when cans are present and actually curing. This not only results in higher efficiency during operation, but also eliminates the need to operate the diodes when the line is down (stopped) for maintenance or line jam. As a result, the uptime of the diode array is equivalent to the actual line uptime.

[0143] From a purely environmental standpoint, in a pro-forma example, the 3,000,000 BTU / hr required to cure the cans and maintain the oven within the correct temperature range can be converted to joules, such as 3,000,000 BTU = 3,165,167,700 joules. Comparing this to the plug power per hour of a radiant heating system, as shown in Table 2, the savings are dramatic when the heat is properly "directed." Even conventional oven heating alone requires more than 12 times the energy theoretically required by a narrowband radiant heating system to cure paint. In other words, with current IBO technology, approximately 92% of the energy consumed is actually wasted. TIFF0007851863000002.tif91116

[0144] Compared to the results of conventional, current standard curing methods, the embodiments described herein clearly result in significant savings of approximately $240,000 per year, based on the cost estimates presented herein.

[0145] This technology offers numerous benefits to can manufacturers. As illustrated in the above example, not only is energy significantly saved, but air pollution is also greatly reduced. The energy and cost savings are actually greater than those shown in the example above, because we have not yet considered the energy savings from not requiring the use of a typical 95-horsepower electric motor, and the energy savings in terms of the high maintenance requirements of the collective conveyor-style ovens. Perhaps the most dramatic benefit for can manufacturers is the fact that, if the embodiments described in this application are properly implemented, the effects of annealing / tempering are completely or almost completely eliminated. As a result, can manufacturers can produce cans with less aluminum. While the weight of some production cans is approximately 0.34-0.39 ounces, it will be understood that the can weight / mass can vary as a function of the exact geometry and material thickness, etc. Also, manufacturers can periodically redesign cans and change the weight / mass (e.g., reduce the weight of the can) by modifying the molds or manufacturing processes. Furthermore, some cans, especially special cans, are designed to increase their weight / mass. If implemented well, this could potentially save 9-14% of the aluminum used. However, reducing the amount of aluminum, such as by 3%, 5%, 8%, or more, would be beneficial. Since approximately 70% of the cost of a beverage can is the cost of aluminum material, this would represent a significant saving for can manufacturers or can users. It would also contribute to environmental benefits in a different way, as it would reduce the need for aluminum mining, refining, manufacturing, and transportation.

[0146] Eliminating the weakening effect of the oven is beneficial in one or a combination of three ways. First, the cans can be made with current aluminum and tools, but will be considerably stronger than current cans because the weakening of the aluminum is eliminated. Second, less aluminum is required to manufacture the cans. Third, cheaper, lower-alloy aluminum or lower-tempered aluminum can be used instead of current, expensive aluminum products. This can also be a combination of these, depending on how the manufacturer chooses to implement the embodiments of this technology described herein.

[0147] There are several novel ways to reduce the amount of aluminum used to manufacture cans when adopting the embodiments described herein. Manufacturers and suppliers of aluminum coil stock charge a standard premium for rolling aluminum to a specific precision and thickness. While aluminum is priced and sold by the pound, there are also considerable process charges for the rolling and finishing processes to a given thickness. Although thinner thicknesses require less aluminum, manufacturers of aluminum coil stock need to roll to high precision specifications and may charge a larger rolling premium than they do for thicker and heavier aluminum to maintain profitability. If a rolling mill adopts this business approach, and if so, no savings may be realized. A more novel way to implement the embodiments described herein is to reduce the cut edge diameter of the blank, thereby reducing the diameter of the resulting cup. A typical starting cup for a 12-ounce two-piece can has a diameter of 5.100 inches. This technique reduces weight by proportionally reducing the cup size, but maintains the same coil sheet thickness, thus preserving the same rolling premium. The first step in the D&I process is deep drawing a “starting cup.” Again, this means the width of the aluminum coil will be reduced, but the thickness will remain the same. Therefore, since it is simply a matter of reducing the width, it should fall within industry standard pricing. By starting with a smaller diameter cup, the final can body will be thinner than conventional finished cans, but without having to pay a premium for rolling the aluminum to a thinner gauge specification. Tool modifications or reconfigurations are understood by skilled toolmakers. The first step in the D&I process is deep drawing a proportionally smaller diameter cup to finish with a proportionally smaller diameter cup. The tool needs to be created or modified so that all its parts are intended and correctly specified for the new diameter.The cups are made with a double-action cupping press, and depending on the design and vintage of the cupping press setup, the tools can accommodate many cup widths. The blank diameter needs to be reduced to minimize the so-called "cut edge." These blanks are tightly nested across the width of the coil at a 60-degree angle to the coil edge, minimizing scrap between blanks and leaving minimal aluminum web between the tangent edges of the blanks. To implement this, the overall width of the coil stock is reduced, and the same number of cup blanks are created across its entire width as conventional-sized blanks with a larger diameter. Alternatively, the coil stock can be modified to create more cup blanks and cups across its entire width while maintaining a wider coil width. In any case, the multi-piece deep-drawing tools at each tool station of the stamping die need to be recreated with the correct new diameter, clearance, and depth. The new punches, draw rings, hold-downs, and all associated tool components need to match the new diameter. The geometric relationships of each tool station need to be adjusted to maintain the relationship between tight nesting configuration and minimal scrap between each blank. Because the tool components will have a smaller diameter, less steel and machining will be required for the tool. Therefore, it should be relatively less expensive than the current larger version. Making smaller diameter cups will require modifications to the copper press tool, but the rewards for such modifications could be substantial. The balance of the copper press, feeder, and overall system should be reconfigurable for the use of new tools or tool changes.

[0148] To properly implement this technology, it is important to have a more detailed understanding of how the embodiments described herein function. The preferred embodiments described herein teach to inject strong infrared narrowband energy as directly as possible into the interior of the can and into the paint itself. This means that directing infrared energy directly into the interior of each individual can does not waste energy by bouncing it around in the factory or attempting to heat the cans in groups or in clumps. While it is possible to implement the embodiments described herein by irradiating the outside of the can, or both the outside and inside of the can, a more efficient implementation is to direct the energy directly into the inside of the can. This is extremely efficient because photons from the narrowband energy actually pass through the paint in a liquid, pre-curing state, and the energy is partially absorbed. It actually passes through the paint, some of the energy is directly absorbed into the paint, is reflected by the aluminum substrate and returns, and passes through the paint again for further absorption. Additional energy is absorbed each time the photon passes through the paint in a return trip. It passes through the paint twice for each subsequent reflection. Because the paint is thin, it doesn't quickly absorb all of the photon's energy, but the photon continues to follow a reflective path until it collides with the next coated surface of paint. Imagine a billiard ball passing through the paint on its inbound path, bouncing off the inside of the can, passing through the paint on its outbound path, and passing through the paint again with additional reflections with each bounce. Continuing the billiard ball analogy, the reason the billiard ball eventually slows down and stops is because all the energy is lost at the bumpers and there is less rolling friction. Similarly, a photon loses energy in two main ways: energy is absorbed each time it passes through the paint, and a small amount of energy is lost in the aluminum due to incomplete reflections. Depending on the wavelength of the narrowband infrared irradiation energy used, several hundred to about 1,500 reflections occur before all of the photon's energy is absorbed by the heating of the paint and aluminum. Of course, the thicker the coated paint, the more energy is absorbed by the paint each time it passes through.A longer path through the paint means that more photons generate and absorb more impacts as they pass through the paint. For example, a steeper angle of entry into and passage through the paint results in a longer path length and greater absorption.

[0149] There are several ways to generate powerful narrowband irradiation energy and effectively direct it inward into the can. While it is possible to use broadband irradiation energy, implementing it effectively and efficiently is extremely cumbersome. For example, the broadband energy generated from a quartz lamp cannot be switched on and off at the kind of speed required for truly clean implementation. The slewing rate and full warm-up time when turning on a quartz lamp are measured in seconds, and the optimal on time across many configurations is one or two seconds, or even just a few seconds. Also, due to their inherent shape and filament configuration, it is extremely difficult to concentrate the energy precisely where it is needed. It is not easy to deliver the correct number of joules to the precise location, but it tends to work well, albeit difficult to control, in fluid configurations (high-volume delivery configurations) where joule thermal energy is delivered to a larger, specific area. Due to their inherent properties, broadband sources may overheat the can too rapidly when attempting ultrafast curing, potentially inducing an annealing effect in part or all of it. There are many advantages to both narrowband irradiation and semiconductor-based generation of narrowband energy. First, it can be switched on and off at microsecond speeds. It generates photon energy only when it is actually receiving a DC voltage input (typically 1.2–3.3 volts). It does not have hysteresis or high blackbody equivalence, which would cause it to substantially continue generating output even after the input has stopped and the current has ceased, as is the case with quartz or gas discharge lamps. Broadband sources typically operate at very high temperatures, which introduces a series of implementation problems. Their presence makes the entire curing environment extremely hot, reducing the reliability of components and requiring optics that can withstand much higher temperatures. This inherently shortens the lifespan, leading to frequent replacements and increased maintenance and downtime. Furthermore, the narrowband mechanism (setup) also facilitates the better implementation of anti-reflective coatings, as the paint can be designed and optimized for the precise narrow wavelength band being used. Broadband anti-reflective coatings are difficult to optimize.Similarly, optical systems and optical coatings, such as cold mirror coatings, can be designed more easily for narrow, specific wavelength ranges. Because lenses focus at different distances for each wavelength, this can be advantageous when designing optical trains for narrowband systems with greater precision. It is important to understand that narrowband can have different interpretations, so we refer to the generation of light or photon energy where the full width at half maximum (FMAX) at a wavelength is typically less than 100 nanometers. This is usually true when the narrowband energy source is a solid-state or semiconductor light source, and broadband fluorescence is not added to the device configuration. While the raw output from an LED is generally inherently narrowband within its range, laser diodes are even narrower, for example, less than 20 nanometers (nm), typically less than ±10 nanometers (FMAX), or as narrow as ±1 nm (FMAX) in certain types. For example, VCELS and SE-DFB devices typically have a bandwidth of less than ±2 nm (FMAX). The exact bandwidth is not as critical as the center wavelength of the output. Wavelength determines the speed at which energy is absorbed by the paint itself. The transmittance of the paint can be measured at various wavelengths, allowing for the selection of the wavelength that achieves the best absorption results. For example, in at least some embodiments, the narrowband infrared energy used for curing (which can be narrowed to ±1 nm (full width at half maximum), depending on the embodiment, as detailed above) is matched to at least one absorption characteristic of the paint. Therefore, in the example of a water-based epoxy paint commonly applied to the inner surface of a can, the narrowband wavelength can be in the range of 800–1200 nm, for example, about 972 nm. As discussed in this application, 972 nm represents the deep penetration wavelength of the water-based epoxy paint. Substantially faster absorption is possible in the range of 1400–1600 nm, for example, about 1454 nm or 1456 nm, depending on the paint, but this trade-off must be determined by the system designer because the wall-plug efficiency is not as high. Similar wall-plug efficiency challenges exist in the 1850nm to 2000nm range, for example, at 1935nm.

[0150] As with many high-power industrial processes, this process must be implemented with safety as the primary consideration by system designers. Regardless of how the embodiments described herein are implemented in their final design, appropriate safety guards are necessary to prevent physical or optical exposure to the hazardous aspects of the technology. Because powerful infrared energy can cause eye damage or blindness, these must be suppressed by safe design. The actual material handling parts of the system have many moving parts that may move or suddenly act to perform their functions, posing a potential hazard. Either physical or electronically sensing guards must be implemented to safely stop movement in the event of human presence. For all aspects of system safety, OSHA, CSA, or CE safety standards must be complied with during system design.

[0151] Regarding narrowband irradiation of systems, extremely strict attention must be paid to the safety aspects of the system. The powerful infrared energy, which is very effective in rapidly curing paint, is extremely dangerous to the naked eye. It is invisible and powerful enough to blind a person or animal quickly before they can blink. Even sunglasses or welding glasses are not sufficient to prevent the powerful photon energy from damaging the eyes, as the filters may be weak and filter out the wrong wavelengths. Some infrared wavelengths longer than those that can actually be used do not penetrate the retina of the eye, but can still damage the cornea, sclera, iris, and / or lens. Often, such wavelengths are mistakenly referred to as "safe for the eye," but this is only true in terms of potential damage to the retina of the eye. The system must be designed to eliminate the possibility of someone being exposed to the eyes beyond a minimum safety threshold to the narrowband photon energy generated by the laser diodes or their arrays. Failsafes, such as a dual backup interlock system, can be incorporated into the control panel or safety guards. The guards must be designed so that they cannot be removed while the narrowband device is powered. Furthermore, the design must prevent jumpering or jerry-rigging so that power is not supplied to the device while the safety guard is removed. In addition, all enclosures and guards must be designed to shield from light when power is supplied to the narrowband device. It is also strongly recommended to design the array so that it is not easily connected to a power source when the array is not in a system, so that service personnel or curious individuals do not want to power on the device and consequently do not get injured. Because the powerful narrowband infrared energy is completely invisible to the human eye, the eye cannot produce a blinking reflex until damage occurs. Exposure to other parts of the body can be unpleasant or cause severe burns, but not as serious as momentary exposure of the eyes to this energy.Therefore, it is necessary to exercise sound design common sense to ensure compliance with the safety standards of all applicable institutions and to verify that the narrowband high-speed curing system is safe. While it offers excellent utility, safety must be an essential part of all aspects of using a system constructed according to the embodiments described herein.

[0152] Furthermore, a powerful method for further improving the performance of the embodiments described herein involves adding special additives to the paint. This dramatically increases absorption at specific wavelengths. By carefully selecting and matching the wavelengths used for curing, more heat can be imparted to the paint, reducing the amount added to the aluminum or steel can stock. In other words, the additive or dew point makes the paint highly absorbent at the wavelengths used, allowing more heat to enter the paint directly rather than being conducted from the metal. Because there is less bounce, less energy is wasted in the non-curing function to achieve the required temperature for curing or cross-linking, thus improving the efficiency of the system.

[0153] Further optimization of the paints used can also be incorporated using the narrowband infrared energy of this curing system. Paint manufacturers can use infrared-sensitive chemical reaction actuators or accelerators suitable for coating purposes on the inside of the can. Functional dyes that exhibit absorption in specific narrowband infrared wavelength ranges are also available. Such dyes are manufactured, for example, by Yamada Chemical Co., Ltd. Narrowband IR irradiation can be used ingeniously by chemical paint manufacturers to improve paints, reduce or eliminate BPA-based paints, or enhance performance in various ways. Some of the reflection inside the can essentially releases energy out through the top of the can's opening. A well-designed system will have reflective surfaces properly positioned to return at least partially of the released energy to the can for further curing until consumed. However, even the most reflective surfaces lose several percent of the impact energy to the reflective material. This is often called Fresnel reflection. Also, some of the energy may be mistakenly scattered or reflected and not returned to the can. A properly designed reflective shape or reflective cone (64) can provide a better distribution of the returned energy, so that more energy is absorbed by the paint through an additional pass through the paint and reflection from the substrate.

[0154] Embodiments involving detailed internal can curing cans can achieve, with significant advantages, the functions of both drying ovens (e.g., drying stations) and pin-chain ovens (e.g., external can surface curing stations) similarly by using precisely directed and controlled narrowband heating technology. As mentioned above, each of these stations performing its drying or curing function in less than 20 seconds prevents tempering, annealing, or weakening of the cans. While the designs and configurations of each oven differ considerably, they share the commonality of using narrowband infrared radiation technology. Narrowband infrared technology uses electricity, which provides the basic energy, to ultimately generate infrared energy, thus completely eliminating the use of hydrocarbons in the ovens. If the entire plant does this for its three main “heat process” functions—drying, ink curing, and internal paint curing—the entire plant becomes unnecessary for hydrocarbon fuel-based heating or oven processes.

[0155] The drying oven or drying station, as shown in Figure 6, is located immediately after the washing process in the can-making process and takes the form of a collective conveying system. An open mesh conveyor belt or open hinged slat arrangement is used to allow radiated infrared energy to be projected from the open end at the bottom onto the can from bottom to top. Ideally, the most efficient design is one that has the largest possible open space through which infrared energy can pass and the largest possible mesh cross-section. The width and speed of the collective conveyor are determined according to the plant's speed and throughput requirements. It is usually 20 to 40 times the diameter of the can, but may be outside this range. However, the desired and optimal width can be easily configured to suit the throughput and production speed requirements of the can manufacturing plant.

[0156] In the application of this drying process in a collective conveyor, the actual heating is carried out in two ways, as described in the embodiments of this application. Narrowband radiated infrared energy is projected upward through a mesh belt or open-space belt onto an inverted can having an opening at the top. The energy begins to bounce inside the can, transferring energy to the can with each bounce. When the photon energy encounters water on its way to the inner wall of the can, it passes through the water and transfers energy to the water quantum depending on the thickness of the water encountered. This interaction continues until enough photon energy is absorbed by the water-aluminum combination and the water is heated to its evaporation temperature. The increase in evaporation occurs at moderate temperatures but is accelerated as the temperature increases. Of course, once the water reaches its gas transition temperature of 212 degrees Fahrenheit, it turns into water vapor, and the water can be removed from the can by air movement alone. Air movement can be provided by fans and blowers configured to introduce fresh, dry air into the can, and the air containing heavier vapor can be discharged through ducts.

[0157] While many different infrared wavelengths work effectively in this application, even higher efficiency can be achieved by utilizing wavelengths that are absorbed much more rapidly by the target. Water is a major component of paint. The shortest wavelength water absorption peak is at 1456 nanometers. Any water absorption peak can be used, but 1456 is the easiest wavelength to manufacture for powerful semiconductor-based irradiation devices. The absorption tendency at approximately 1450 nanometers is several times greater than, for example, the absorption rate at 1000 nanometers. Another absorption peak exists at 1932 nanometers, which has about four times the absorption of the 1450 peak. However, manufacturing a semiconductor-based irradiation device at 1932 nm is extremely difficult compared to 1450 nm. The wall plug efficiency of semiconductor devices decreases as the wavelength increases. However, since aluminum has greater absorption at approximately 1000 nanometers than at longer wavelengths, there may be optimization trade-offs to consider. Therefore, application engineers need to determine whether the additional absorption rate is worth the power loss and wall-plug efficiency reduction typical of devices at longer wavelengths.

[0158] The methods described so far utilize narrowband techniques with a collective conveyor, but it is also possible to configure a series conveyor to dry individual cans. The configuration is very similar to the internal workings of can curing as described above. The main difference is that the cans are not yet coated with paint and do not need to be heated to the same high temperatures as when curing cans with painted interiors. The purpose of the drying oven is simple: to remove any remaining deionized water that has not yet been discharged or evaporated from the cans. Again, evaporation of water is accelerated by rising temperatures, but it does not need to exceed the boiling point of 212 degrees Fahrenheit at sea level. At higher altitudes, evaporation is faster because the temperature does not need to be as high to change the state to water vapor.

[0159] Pin chain ovens or can exterior surface curing stations require a completely different application of narrowband technology. The purpose of a pin chain oven is to cure the ink that has just been printed on the outer surface of a can. In practice, the ink is not completely cured in this oven, but a short exposure in a pin chain oven is sufficient to cure it, without rubbing, smudging, or ruining the print until further curing is performed in an IBO (Instrumental Battering Oven).

[0160] The application requirements for the pin chain oven are that it be properly configured to fully utilize the aiming and focusing capabilities of the laser array. Since the radiated energy is directed outwards from the cylindrical circumference of the can, some of the energy is absorbed by the ink and propagates through it, while some is absorbed by the aluminum substrate. More thermal energy is transferred to the ink as it bounces off the aluminum substrate, returns to the ink, and passes through it before exiting. However, unlike when the energy is projected into the can, in this application care must be taken to ensure that the energy is returned to the can rather than being wasted by random reflection into space. A mirror can be placed around the can to reflect the energy back towards the can. However, the problem with mirrors is that, because the angle of incidence is equal to the angle of reflection, precisely positioning a mirror that actually reflects the energy at the desired location on the outside of the can is extremely difficult, if not impossible. Modeling shows that after the first two reflections, control over the direction of reflection is almost completely lost.

[0161] A more elegant way to reflect energy back to the can is to utilize a corner cube reflective sheet. While this sheet may have different configurations, for example, it is configured to have multiple (e.g., tens, hundreds, or thousands) appropriately sized corner cube reflectors to achieve the desired results depending on the implementation. Various applications and uses of such sheets and related technologies are fully described in U.S. Patent Application No. 13 / 102,588 (and titled “Corner Cube Irradiation Control”), filed May 6, 2011, which is incorporated herein by reference in its entirety. Essentially, the sheet needs to be positioned as perpendicular as possible to the direction from which the reflection is expected in order to accurately return energy to the point from which it is reflected from the can. Figure 9 shows a corner cube reflective sheet, which is arranged around the can but beyond the “no fly zone” where the can must travel on the conveyor belt. Great care must be taken to ensure that the can does not touch anything or have its ink smudged. The concept that must be effectively implemented is to maximize the amount of narrowband energy that directly affects the can, and to utilize as much reflected energy as possible to return it to the ink-coated outer surface of the can.

[0162] Laser arrays can be aimed and focused with such precision that they allow for highly concentrated energy to be used to heat the ink and cans very rapidly. If the energy is concentrated on the sidewall of the can as it passes, it will only be properly focused for a brief moment before being wasted as it goes between the cans. One solution to this is to use servo or galvanometer-controlled mirrors to integrate and track the passing cans, so that the energy remains focused on the correct position on the can body for a longer period of time. While this is a viable solution, it requires additional mechanisms and advanced functionality, and may present maintenance and setup issues.

[0163] Another solution is to turn off the array when the can is not in the focal area. Then, when the next can comes into view, the array is turned back on at the necessary time. Doing this strategically, power can be saved by coordinating the placement and timing so that two or more arrays share the same power supply. DC power from the power supply is simply switched to the array that needs power when it needs it.

[0164] An additional method to enhance rapid heating for curing ink is to inject some or all of the heat into the can. This has the advantage of requiring less reflection management because the energy injected into the top of the can opening essentially bounces around until it is absorbed or completely reflected back from the can. Energy injection for rapid heating is possible by determining the timing of a powerful energy pulse when the can opening perfectly matches the focal pattern, and by setting up one or more highly focused arrays so that the energy is focused at the edge of the can opening. Since the photon energy cannot be kept on for longer than a brief pulse before the can is out of position, it is usually necessary to have a series of arrays that sequentially inject more energy as the can moves along its path through the fast narrowband oven. However, laser diode arrays can have input current levels in instantaneous pulses that are much higher than input current levels in steady-state operation. There are other ways to inject high-power narrowband photon energy into the edge of the can opening. This involves designing a material handling mechanism to be applied to the can, either using an indexing method or a continuous tracking similar to the concepts taught in internal bake ovens. The only major difference is that the can needs to be kept under vacuum to prevent the ink from bumping, smudging, or bleeding.

[0165] One of the advantages of using electric or narrowband irradiation throughout a can factory is that hydrocarbon fuels, CO2, nitrous oxide, and other contaminants can be completely eliminated throughout the entire process, from the aluminum coil to the finished can.

[0166] Another benefit of eliminating hydrocarbon fuels, CO2, nitrous oxide, and other combustion pollutants is the dramatic improvement in communication with people living near the plant who might be emitting foul-smelling or toxic pollutants from one of the ovens. Continuous maintenance is needed, from time to time, by knowledgeable people who are difficult to meet, to ensure that combustion is clean, properly cleaned, and that ovens are properly maintained and optimized. Environmental advocates are strongly opposed to natural gas or hydrocarbon fuel ovens in canning plants.

[0167] Another advantage of using electric or narrowband irradiation throughout a canning plant is that it allows the entire plant to be powered using renewable fuel sources such as wind power, hydropower, or solar panels / photovoltaics.

[0168] Another advantage is that, when utilizing narrowband irradiation, it can be obtained from any of the three types of ovens described herein. While drying or curing can be performed rapidly when the embodiments described herein are properly implemented, with currently available techniques, rapid drying or curing results in rapid annealing and strength loss. In this curing method, the time at a given temperature is too short, making it impossible for the grain to grow, which is the basis of the weakening phenomenon that occurs with longer curing times. Because rapid drying or rapid curing, or both, are employed, the aluminum remains stronger and therefore makes for a stronger can.

[0169] Another advantage of narrow-band curing and drying is that the benefits increase progressively with each successive oven in a plant where this technology is implemented. Therefore, by using high-speed, narrow-band technology in all three ovens in the process to manufacture cans, the aluminum after the D&I process can retain all of its inherent strength. In other words, the D&I process has its own effects on the aluminum particle size and hardening, and annealing currently occurs due to the ovens. However, by exclusively using narrow-band, high-speed drying / curing, annealing does not occur at the end of the process.

[0170] Another significant advantage of implementing rapid narrow-band techniques for curing and drying is the ability to save a substantial amount of aluminum—10–14%—in the process. Aluminum savings can be optimized as a function of many variables, as there are so many differences in can-making tools, reduction steps, and oven treatments. Lower aluminum usage can be achieved by manufacturing cans of the same strength from thinner coil stock material. The main advantage of this alternative is that, while maintaining the starting coil stock thickness unchanged, changes in tools for manufacturing the same basic can shape, liquid capacity, and specifications allow for the selective formation of thinner cans from smaller diameter blanks, thus significantly reducing the amount of aluminum required for can manufacturing.

[0171] A further benefit of these advantages is that a predetermined number of cans can be manufactured from a coil strip of the same thickness but narrower than conventional methods.

[0172] Another advantage of implementing narrowband technology in these applications is the ability to conserve raw material resources in various ways. It reduces carbon emissions, processing costs, and raw materials throughout the aluminum manufacturing and can-making processes. It reduces transportation costs from the aluminum rolling mill to the can-making plant, from the can-making plant to the filling plant, from the filling plant to the logistics warehouse, from the logistics warehouse to the retail store, and from the retail store to the consumer using the product. It also reduces tonnage taxes and resources involved in the recycling stream. Cans made this way are thinner, making them easier to crush and briquette, and allowing them to be melted and recycled with less energy.

[0173] Narrowband technology is digitally programmable and highly controllable, so the can never be heated above its ideal temperature, saving energy and preventing unnecessary metal weakening or annealing.

[0174] Another advantage of implementing these ovens with narrowband technology is that the loop can be closed by checking the can temperature using infrared sensors, thermocouples, or infrared cameras, and the narrowband energy supply can be adjusted to maintain optimal energy use and temperature.

[0175] When aggregate conveying is implemented, energy can be saved by optimizing the projection of irradiation energy. For example, if some upstream body makers and trimmers are not being used for maintenance or other reasons, conventional broadband ovens would naturally have more width than necessary, but with this approach, cans can be processed through the oven in a narrower flow without requiring such extra width. Current broadband ovens present an all-or-nothing choice: turn them on or off. This is also advantageous when production cycles are shortened or adjusted, making it easier to match production volumes to demand or needs.

[0176] Another advantage of this technology when used in bulk conveying is its ability to measure the temperature of the cans across the entire width of the conveyor and close the loop to quickly correct the temperature and prevent the cans from being overheated or underheated. Multiple non-contact sensors, such as infrared sensors or infrared cameras, are positioned to measure and verify the temperature, and the irradiation array is controlled by sending the measurement information to a control system and adjusting the output or conveyor speed accordingly. The temperature can be adjusted anywhere along the width of the conveyor or across the entire mass on the conveyor if the heating is not consistent across the entire conveyor or if convection airflow or something else is cooling some cans more than others.

[0177] Another advantage of implementing narrowband technology in a pin chain oven is that the array is turned on when a can reaches the irradiation position and turned off when the irradiation position is between cans. This has the advantage of eliminating the waste of drawing in input power energy even when the irradiation position is between cans.

[0178] Another advantage of narrowband pin chain ovens is that power can be shared between two or more arrays. With proper planning, the number of power supplies required for system implementation can be reduced, lowering system costs. When properly implemented, the thermal cycling of electronic components is less severe, which can also extend the lifespan of the power supplies.

[0179] A further advantage of maintaining the strength of aluminum is that it allows for greater bottom inversion strength and safer application of greater pressure within the can, even with the same thickness of can material. Another advantage of fully maintaining the strength of aluminum is that it allows for the manufacture of cans with thinner material while maintaining the predetermined strength of cans manufactured using conventional overbuild methods.

[0180] By fully maintaining the strength of the aluminum, we gain the advantage of being able to use narrower cut strip coils to create smaller diameter blanks, then smaller diameter cups, and then proceed with balancing the process. This allows us to reduce the amount of aluminum used by approximately 10-14% while maintaining similar strength.

[0181] Maintaining the full strength of the aluminum without annealing or weakening offers the advantage of being able to manufacture stronger cans using the exact same tools and aluminum substrates.

[0182] A further advantage of this technology, which enables the production of lighter cans, is the reduced mass of aluminum being heated. This means that, whether in a drying oven, pin-chain oven, or inside bake oven (IBO), the number of joules of energy required to heat the can to achieve the desired effect for the intended purpose of that oven decreases proportionally to the mass. This not only reduces energy costs but also increases the possible throughput speed. Therefore, the time and energy required to heat each can to the target temperature or to achieve the intended purpose can be reduced.

[0183] Another advantage of implementing pin chain conveyors with this high-speed, narrowband technology is that it can reduce the size of the oven by more than 75%.

[0184] Further advantages of implementing narrowband technology in pin chain ovens include a dramatic reduction in ambient heat released to plants near the oven and a dramatic reduction in sound pressure levels generated by all moving chain / belt components and convection blowers.

[0185] Another advantage of implementing this high-speed narrow-band heating technology throughout the entire plant is that it can significantly reduce the floor space required for the can manufacturing plant. Ovens are among the most space-consuming pieces of machinery and equipment in a plant, and if properly implemented, the space required for each can be reduced by more than 75%.

[0186] A further advantage of this technology is that it allows for the ability to direct, concentrate, and control energy with great precision in its implementation. The most suitable type of narrowband device for implementing this technology is typically a laser diode, because laser diodes, especially when configured in an aggregated array, can generate very high output levels with great straightness. Fiber lasers and other narrowband devices can also be utilized. When using any type of laser device, an infrared device is usually chosen, but the output photons or light energy can be formed with modalities similar to those used for visible light. Thus, any of the elements of refraction, diffraction, reflection, and diffusion can be used very effectively by those implementing the embodiments described herein to help ensure that energy is obtained where it is needed, at the appropriate time and intensity. This is crucial for achieving overall system efficiency and obtaining heating rates that produce a great many advantages.

[0187] If the narrowband pin chain oven is properly implemented, there is no need to rotate or turn the can as it passes in front of the illumination unit. Due to the aiming accuracy and the gap between the cans, it is possible to accurately illuminate the entire 360 ​​degrees of the can without rotating it.

[0188] Here again we refer to the drawings. The narrowband drying oven is configured to function as a collection conveyor to replace, supplement, or enhance a gas drying oven (614), for example, as referenced in the system shown in Figure 6. Figure 12 shows an overhead view of the collection conveyor. This shows the bottom (121) of the cans, as the cans are inverted to drain with the help of gravity. The belt material (112) is illustrated to move the collection of cans in the direction (114). The belt (112) only needs to be transparent to some extent to the light or wavelength of irradiation used by the narrowband irradiation source. Various types of materials can be used, such as very coarsely woven mesh fabrics or belt materials of some kind of chainmail or chain link. Preferably, a very high percentage of open space is required on a vertical cross-sectional basis. The idea is to let the maximum amount of light pass through and cause little back reflection. The higher the transparency or openness of the belt, the less the belt heats up and the more energy is transferred to the can components being processed. A thin, strategically shaped, hinged vertical metal slat with a large vertical cross-section and a very small horizontal cross-section works very well. This is because it has sufficient strength throughout the width and length of the belt, while still having plenty of pass-through space in the vertical direction. Also, the vertical sidewalls of such a hinged conveyor component can provide very good reflected light from its vertical sidewalls, which eventually reach the can and assist the heating process. Whatever material is chosen for the belt, it must be able to handle the heat from irradiation at very high load cycles and must also be resistant to any remaining dripping hydrofluoric acid or hot water. The belt needs to be structurally rigid enough so that it does not sag across the width of the belt and does not cause problems with the movement and positioning of the can. The belt material (112) is supported by a frame (111) along the edge and additional structures (110). The additional structures (110) are configured as needed to structurally align and position all sections and components of the conveyor, as well as the drive components, for proper function.Similar to a typical conveyor, there are usually pulleys at each end, at least one of which is driven by a motor system. This motor system can be adjusted to maintain the correct speed throughout the drying process for effective function. For best performance, the section (112A, Figure 13) located just below the belt and carrying the cans is driven to pull the belt through the working section of the oven rather than pushing it. The cans need to be moved away from the acid and deionized water rinsing tanks while the return section of the belt (112B, Figure 13) moves under the superstructure and under the irradiation unit. Along both sides of the conveyor, there should be some kind of railing structure (113) that simply functions to surround the cans and move them together in the pack, so that they do not separate from the conveyor and slide off.

[0189] Because the irradiation is powerful infrared radiation, it is crucial for safety to completely enclose the conveyor system and keep the infrared photon energy completely away from human eyes and bodies. Because infrared radiation is invisible, the normal blinking reflex of the eye does not function to protect the eyes and retina from the powerful light energy. Infrared radiation can easily melt or damage wire insulation, plastic parts, and many other things without being noticed, so this must be understood when designing a high-speed narrowband oven. All items directly exposed to the energy must be able to continuously reflect the energy or withstand the heat they may be exposed to. Practitioners of the embodiments described herein must always be mindful of laying out any configuration of narrowband irradiation in such a way that there is no bounce path that would cause the energy to exit the oven and enter the eyes in any way. Typically, baffles and shrouds, or bends under or inside the shrouds, can be effectively used to ensure sufficient bounce of the energy so that the energy concentration is reduced or the energy intensity is reduced to a safe level before it leaves the conveyor cover. In any case, the energy must be sufficiently absorbed or diffused to a safe level before a path for the energy to escape from the oven is created. Furthermore, signage must be appropriately placed to warn people and operators of the inherent hazards that must be avoided in powerful IR radiant energy-based systems. Electricians or technicians must be warned about these hazards to avoid performing dangerous operations when working with, troubleshooting, or otherwise engaging with these systems. In at least one form, the control system can be made to function to monitor (e.g., through appropriate sensors) whether personnel are entering the area of ​​interest or whether unwanted energy is being contained.

[0190] As shown in Figure 12, which indicates the line of sight in Figure 13, Figure 13 is a cross-sectional view of a conveyor along its length. This shows cans (121) resting on a belt (112A) with the closed, dome-shaped ends of the cans facing upwards. In this drying station according to the embodiment described herein, irradiation arrays are arranged within an irradiation housing (130), the number of which depends on the amount of total and local irradiation power required for a particular application and speed. An implementer of the embodiment described herein should be well aware of and understand what the irradiation power density from the arrays used will be. Using both classical calculations and practical analysis, the number of joules of energy required to raise the temperature of the paint, ink, or water remaining inside / on the can, along with the energy absorbed by the can itself, can be determined.

[0191] As already shown, while it may be desirable in some cases, raising the temperature of the cans and the remaining water above the boiling point of 212 degrees Fahrenheit is generally not recommended. Higher temperatures increase the tendency of water to evaporate, a tendency further enhanced by airflow that can carry away the evaporated water. As many housings (130) as needed can be arranged along the width and length of the conveyor to provide the amount of energy required to raise the heat quickly enough to perform the drying operation in a timely manner. One type of standard narrowband laser array available can produce synchrotron photon energies slightly over 300 watts. Arranging such arrays end-to-end along the length of the housings, such as (130), allows for continuous irradiation output across the width of the belt (112). A thorough understanding of the output pattern is necessary to ensure that the arrays or individual devices are positioned to provide a relatively uniform energy field at the location of the target cans. With meticulous technical care, sufficiently arranging these banks, housed in housings like (130), along the length of the conveyor (111) can provide sufficient irradiation output with a good, consistent power density for almost all drying applications.

[0192] The faces of the array (141) are pointed upward through a mesh belt into the open end of the can (121), where the walls are still straight. The irradiation (151) is roughly reflected and guided by a baffle reflector (132), directing the energy towards the target. Lenses, microlens arrays, or diffusers can be selected and used to broaden or narrow the beam accordingly to ensure that the energy enters the can in the best possible way. Particularly in the initial stages of the drying operation, liquid water may drip from the can, so an optically transparent window (133) can be placed to protect the array from direct dripping water. The window is optically transparent or transparent in at least one form, at least at the wavelength and / or wavelength range applied in the drying process. The protective window (133) is best mounted at a slight angle to facilitate water drainage, like a roof. The protective window (133) should be properly sealed where it meets the reflective structure (132) to prevent water or liquid moisture from entering the sealed chamber. The protective windows may also be fitted with an anti-reflective coating that functions at the applied wavelength or wavelength band. The liquid water is carried by gravity down the slope 133 into a drainage trough or gutter (134). The drainage trough or gutter is appropriately positioned at or near the edge of the protective windows to allow the liquid water to be carried away. In any case, it is wise to position the system so that the array is protected, less susceptible to damage, and not exposed to water or other random contaminants that tend to fall from inside the belt or cans.

[0193] The most common basic narrowband device is the laser diode. Generally, they are assembled into arrays of tens to hundreds of devices (141). Their efficiency can actually vary, depending on many factors, and is typically between 20% and 65% "wall-plug efficiency." The wavelength chosen for implementation is the biggest factor in efficiency, but the style of the chosen device is also a determinant. Input DC electrical energy that does not exit the laser's output facets as light or photon energy is converted into heat, warming the device and, consequently, the entire array. One of the best devices, combining efficiency and overall robustness, is the surface-emitting device. Specifically, SE-DFB devices have proven to be robust in performance, yet can run continuously at ideal drive voltages for excellent cost-effectiveness and practicality.

[0194] Excess thermal energy within the laser diode array needs to be removed. In typical high-load cycle industrial applications, either water cooling or refrigerant-based chiller cooling is desirable to keep the semiconductor devices in the temperature sweet spot. The colder it is, the longer it can last, and the higher the output. Cooling is not possible if it is too cold or prone to condensation, which may damage it for other reasons. Generally speaking, semiconductor laser arrays should be kept below normal room temperature to extend their lifespan. Cooling tubes and wires (131) pass through the housing (130) and connect to each of the arrays within it. Various types of cooling can be employed in industrial applications. A variety of cooling or cooling technologies can be employed, from heat exchangers to refrigerant-based chillers. Rooftop units that utilize cooler season temperatures provide an additional benefit for effective cooling. Cooling towers, geothermal systems, or large-scale water facilities can also be used very effectively if properly designed.

[0195] The fan and blower shown at 139 in Figure 13 should be implemented as needed to provide sufficient airflow for effective drying. A lamellar airflow can be used directly below the belt (112A) to continuously vary the gap between the irradiation array protective glass (133) and the bottom of the belt (112A). In at least one embodiment, a faster airflow can be directed towards the mouth of the can to remove water vapor more efficiently. Practitioners of the embodiments described herein should take care to provide sufficient airflow to reinforce the irradiation for effective drying, but not to provide so much flow or air pressure that it tends to lift the can (121) off the belt (112A). With a little experimentation, a suitable implementation that provides very fast drying can be achieved without creating time for the aluminum to be in temperature conditions that would anneal and weaken it.

[0196] Furthermore, using a heat exchange blower to keep the array cool provides a dual functionality and improves efficiency. The air coming out of the heat exchanger or chiller is already slightly warmed, but this has the advantage of guiding and accelerating the air as it passes through the opening of the can, helping to remove the water vapor-laden air seeping from the can.

[0197] Furthermore, it should be noted that this system may include an additional blower to blow away or dry any water that may accumulate in the dome (which is inverted) of the can. The blower can be operated before or during the drying process.

[0198] Referring to Figure 10, a pin chain conveyor is shown in this exemplary embodiment, but it should be understood that other types of conveyors, such as vacuum conveyors or belt conveyors, can also be implemented. The pin chain conveyor, along with the link belt (162A), is shown enlarged in Figure 10. Note that the enlarged view is shown for conceptual clarity. The array of sprockets is arranged in a single plane, but the link belt moves through the oven in a zigzag pattern, with straight sections between each sprocket ranging from 8 to 15 feet. The purpose of the zigzag or meandering is to extend the time that freshly inked cans spend in the oven. The meandering plane of the link belt is tilted slightly backward so that gravity helps keep the cans on the pins during high-speed travel. Since the ink is wet, it is important that nothing touches the cylindrical outer circumference of the cans, as this would contaminate the wet ink. The pins (161), formed by the length extensions of the hinge pins at each belt joint, are designed to be somewhat longer than the depth of the cans. In this way, the cans are separated from each other, away from the link belt, and space is maintained between them so that they can be effectively dried in the oven. Figure 10 shows how the cans are supported by the pins as they pass through the pin chain oven.

[0199] The cans have a certain degree of freedom. For example, can 122A is simply perfectly centered with respect to the pin (161) on which it rests. Due to the pushing, gravity, or centripetal force generated when the belt vibrates around one of the sprockets, the can may end up in that position. More generally, however, if the current winding direction of the conveyor (164) is against gravity, the can may settle in a position like 122B, but the same can may collide and be repositioned to a position like 122C, for example. The cans move slightly on the pins but are held apart from each other to prevent ink from bleeding. The embodiments described herein can be implemented in pin chain configurations similar to or even identical to those present. For example, referring to Figure 6, a pin chain conveyor / oven or deco oven (e.g., deco oven (624)) (and / or, optionally, a base coater oven (618)) can be replaced, supplemented or enhanced in appropriate configurations according to the embodiments described herein. In this regard, for example, Figure 9 shows a curing station or irradiation station and a diagram along the long axis of a pin (161) similar to that in the diagram of the multi-link conveyor (162B). Figure 9 shows a can (122) passing through an array assembly housing (143). The portion of the can closest to or perpendicular to the array (143) is made irradiated by the nearly orthogonal array. In at least one form, part of the irradiation may be aimed to cure the bottom coating, which may be applied by a bottom coater in the system (see, for example, Figure 6). Returning to Figure 9, an encoder (162) tracks the progress of the conveyor. The control system can turn on DC electricity to the array (142) to send a strong narrowband irradiation around the can closest to the array. Because the ink is very thin, energy passes through the ink, but some of the energy is immediately absorbed directly by the ink. Much of the photon energy that travels without being absorbed collides with the aluminum can body (122), which is the substrate beneath the ink. When a photon collides with an aluminum can, some of its energy is transferred to the aluminum, and then most of the energy is reflected.In a normal reflection from a simple flat reflective surface, the angle of incidence is equal to the angle of reflection. This is true for each minute position, but a beam of photons has a beam width. Therefore, when it hits a curved surface, the energy is reflected in a curved spread where it is not all evenly distributed. The engineering challenge is to not waste the reflected energy and to place a mirror or some kind of reflective device to return it to the can. The problem is that a planar mirror has the property that the angle of incidence and the angle of reflection are equal. Unless the mirror is angled perfectly toward the surface of the can, the energy is reflected at an undesirable range of angles, and most of it is likely to miss the can completely. Even if the first bounce reflects it where it's needed, the next bounce may go in a random direction. There is a way to configure this better. In Figure 9, if we trace ray 153 to the point of impact on the can, it bounces back as ray 154. In relation to the embodiments described herein, different types of mirrors or optical devices can be implemented (at least some of which have the aforementioned challenges), but when corner cube reflective sheets (171) are implemented, they function to reflect the light rays 155 back to a location very close to the location on the can surface where the initial reflection occurred. That is, the corner cube reflective material or sheet is strategically positioned so that the irradiation reflected from the outer surface of the can is subsequently reflected by the corner cube reflective material and returns substantially to a location on the outer surface of the can close to where the irradiation was first reflected.

[0200] This process is repeated many times until the energy is depleted. Each time photon energy passes through the ink, is reflected by the aluminum, and passes through the ink again, the temperature of the ink rises. This energy utilization can be greatly improved by positioning the corner cube reflective sheet material as perpendicular as possible to the direction from which the reflection is expected to come. Another example is ray 156. Ray 156 returns from its initial bounce off the can and is reflected at an odd angle by something on the array itself, creating ray 157. Ray 157 collides with the surface of the can and is reflected as 158. With the corner cube reflective sheet (171) properly positioned, ray 159 returns to the can again. Several other examples of this same type of optimization are shown in Figure 9.

[0201] Figure 11 is an overhead view of multiple curing or irradiation stations targeting a can along a path. It can be seen that irradiation (152) is projected onto the can at various angles. As the can passes through the multiple irradiation stations, the photon radiation energy ultimately hits all surfaces of the can directly. Irradiation housings (143) are positioned at various angles along the conveyor to ensure that the direct radiation energy affects the correct position of the can (122). Implementers of the embodiments described herein can spread out the arrays so that there is more space around each array for the corner cube reflective sheets (171). Alternatively, the arrays can be positioned closer together to reduce the temperature loss that actually occurs between radiation energy doses at different stations. There are engineering trade-offs that need to be experimented with, taking into account specific geometries and application environments. For example, sheets of corner cube reflective material or corner cube reflective arrays can be strategically positioned between arrays, substantially perpendicular to the tangent to the outer surface of the can, and relative to each curing or irradiation station. As mentioned, the multiple irradiation stations are configured, in at least some forms, to have arrays positioned at various angles designed to cure the ink or paint on the entire surface or around the circumference of each can.

[0202] Figure 14 shows a pin chain conveyor gradually approaching a vacuum flat belt conveyor (183). The conveyor (183) has an angle (186) between the plane of the top of the cans on the pin chain conveyor and the plane of the surface of the vacuum belt (182). Creating a gentle approach angle allows for a very stable, flat flow of cans (122) along the flat surface of the vacuum belt (182). This can be used to increase can stability and can optionally be used in combination with the configurations shown in Figures 9 and 11. A vacuum plenum (185) draws air through the vacuum holes in the vacuum belt (182) to firmly pull the bottom of the cans (the plane on which open cans are placed on the table) onto the vacuum conveyor belt.

[0203] In at least some of the embodiments described herein, the system includes a heating system / subsystem and a suitable decomposition system / subsystem to address the release of undesirable volatile organic compounds (VOCs) during the curing process. In this regard, undesirable VOCs may be generated and released during the curing process of paint inside a can or during the curing process of ink outside a container. Accordingly, according to the embodiments described herein, the heating system / subsystem in the curing process is provided with a ventilation configuration to maintain a threshold temperature for VOCs in order to prevent undesirable accumulation of VOCs that may occur before the VOCs reach a decomposition system / subsystem, such as a catalytic decomposition system including a catalytic oxidation system and / or a thermal decomposition system including a thermal incinerator, oxidizer or afterburner, for destroying or burning off undesirable VOCs and other outgassing associated with curing, such as VOC coating in an undesirable way and / or in an undesirable location. In at least one embodiment of the invention, such as internal curing of a can, the threshold temperature is at least about 290 degrees Fahrenheit, insofar as the VOCs generated during the internal curing process of a can contemplated in this invention typically condense at a temperature below such a threshold. Of course, the threshold temperature will vary depending on the application and the type of VOCs actually generated. The threshold temperature is sought in order to carry away or remove the VOCs from their area and, in most cases, to decompose them. For example, inks coated on the outside of a can may contain various OCs or vaporous products that are generated during curing.

[0204] To cure the inside of the can, a suitable heating system or subsystem, such as a heating coil, is provided to heat the vent pipe, for example, to maintain the temperature of the VOCs at a sufficiently high level until they are transported to the catalytic converter station, as shown in Figure 7. More specifically, referring particularly to Figure 7, the vacuum port or vent pipe 75 may, in at least some embodiments, include a heating device such as a heating coil 310, which maintains the temperature inside the vacuum port at least at a threshold temperature while vapors containing VOCs and other generated compounds are drawn out of the curing process. The vent pipe 75 can take any of a variety of configurations to achieve the objective of drawing out undesirable vapors from the curing process. Furthermore, although the vent pipe 75 is shown to include a heating device such as a heating coil 310 in at least some embodiments, the heating coil 310 and the implementation of the heating coil associated with the vent pipe 75 can take various forms. For example, the heating coil 310 may be located inside the passage of the vent pipe or outside the vent pipe (e.g., wrapped around it). As an alternative, the vent pipe can have a multilayer configuration with heating coils arranged between multiple layers, as shown exemplified in Figure 7 (section AA). By providing an insulated outer layer, heat loss can be reduced, and the cost of maintaining the inner wall of the pipe above a minimum threshold temperature can be lowered. Furthermore, other suitable heating mechanisms can be implemented, either supplementing or replacing the heating coils.

[0205] It should be recognized that the vapors released during the curing process, including VOCs and other generated compounds, are transported through the vent pipes 75 to the catalytic decomposition system or unit or the pyrolysis system or unit 350, where they are decomposed, discharged, or removed. This structure is typically shown in Figure 7. However, the network or system of vent pipes 75 extending from the curing station can be implemented in any of the various suitable methods that will become apparent to those skilled in the art by reading this specification. It should also be understood that the pyrolysis or catalytic decomposition unit 350 can take various forms. As mentioned above, the decomposition unit can take the form of a catalytic decomposition system, such as a catalytic oxidation system. The decomposition unit can also take the form of a pyrolysis system, such as a thermal incinerator, oxidation device, or afterburner.

[0206] Similarly, the internal curing embodiment of the can described in relation to Figure 8 can also be supplemented with a system to address undesirable VOC emissions during the curing process. In this regard, referring to Figure 8, a ventilation unit 320 can be positioned to transport vapor containing VOCs and other generated compounds to a pyrolysis or catalytic decomposition unit 350. The ventilation unit 320 can take various forms to accomplish its function and can be positioned in various different locations (e.g., near the top of the container 22). Also, a suitable vent pipe 375 (including a vent pipe with a heating mechanism such as a heating coil) can be implemented to transport vapor from the ventilation unit 320 to the decomposition unit 350. In some forms, the vent pipe 375 is directly connected to element 240 (in place of or as an auxiliary to the ventilation unit 320), similar to the vent pipe 75 in Figure 7. Similar to the vent pipe and decomposition unit in Figure 7, these components can take various forms, including those described above and others.

[0207] To transport the sufficiently heated VOCs to the catalytic converter station for curing the surface ink, the airflow system can be equipped with appropriate heating and ventilation. More specifically, referring here to Figures 9 and 11, an appropriate ventilation system, such as the ventilation unit 330 shown here as a representative example, can be provided to carry away and remove undesirable VOCs. In this regard, a ventilation tube or port 375 (such as the vent pipe 75 in Figure 7) equipped with an appropriate heating function (such as the heating coil 310) can be implemented to remove vapors containing VOCs and other generated compounds from the curing oven and transport them to a catalytic decomposition or pyrolysis system or unit 350 for processing and / or removal.

[0208] In this regard, the ventilation unit 330 can be positioned outside, above, or to the curing station in Figure 9 or 11. The ventilation unit 330 can also be positioned within or between the reflective arrays, if necessary. As an alternative or supplement, under appropriate ventilation conditions, vent pipes can be positioned in various locations (with or without the ventilation unit 330) to receive steam and transport it to the decomposition unit 350.

[0209] It should be understood that the problem of VOCs and other undesirable vapors or emission products can be addressed in a variety of ways that are obvious to those skilled in the art. The configurations considered herein are merely illustrative. A reader of this disclosure and the problems presented will be well able to devise other approaches that fall within the scope of the embodiments described herein.

[0210] Implementing these narrowband irradiation techniques in IBOs, pin-chain ovens, and drying ovens (and, in some examples, base coater ovens) not only enables a far more efficient heating scenario throughout the can factory by performing all oven heating operations within the can factory, but also eliminates all hydrocarbons, nitrous oxide, and CO2, while simultaneously eliminating the heating x time scenario that causes annealing and weakening, which frequently occurs in can factories. This reduces operational problems and increases uptime rates. It will be understood how the implementation of high-speed narrowband ovens by the embodiments described herein can be further optimized to provide better can manufacturing. It will also be understood how it can be extended to other aspects of can or container manufacturing, such as drying / curing compounds in beverage shells. It can be used very effectively to dry newly inked decorative sheets to replace or refresh wicket ovens in food can factories. The advantages are numerous, and the applications of the embodiments described herein are far broader than those described herein.

[0211] For example, the concepts taught herein regarding how to implement the embodiments of narrowband infrared curing described herein are intended to help those who wish to configure the embodiments described herein to suit specific application and production needs. These examples demonstrate how many different ways exist to implement the embodiments described herein, far beyond the specific examples given. Individuals or teams skilled in their respective fields can extend the new concepts to meet their own application requirements.

Claims

1. Including the first station, the second station and the third station, The first station includes a first array of semiconductor-based narrowband irradiation devices arranged to irradiate and dry cans through a mesh belt or open-space belt of a collective conveyor, or to irradiate and dry individual cans individually on a series conveyor, and the first station is configured to dry cans in less than 60 seconds. The second station includes a second array of semiconductor-based narrowband irradiation devices arranged to irradiate and cure the ink coated on the outside of cans being transported on a conveyor belt, and the second station is configured to cure the ink in less than 20 seconds. The third station includes a third array of semiconductor-based narrowband irradiation devices arranged to electrically heat the inner surface of each can that has moved into the curing zone, and is configured to use optical elements positioned outside the open ends of the cans so that the paint on the inner surface of each can in a series of cans reaches a critical temperature in less than 20 seconds, which prevents the cans from tempering or annealing, allowing the paint linking curing process to proceed. A system for use in can manufacturing, for cleaning, decorating, and / or spraying paint onto the inside of cans.

2. The system according to claim 1, wherein the first station is configured to dry the can in less than 50 seconds, less than 40 seconds, less than 30 seconds, or less than 20 seconds.

3. The system according to claim 1, wherein the second station is configured to cure the ink in less than 15 seconds, less than 10 seconds, or less than 5 seconds.

4. The system according to claim 1, wherein at least one of the third stations is configured to heat a can to a critical temperature for promoting linking or cross-linking of the paint in less than 10 seconds, less than 5 seconds, or less than 2 seconds, and the paint is optimized for narrow-band curing.

5. The system according to claim 1, wherein at least one of the first station for drying the can in less than 60 seconds and the second station for curing the ink in less than 20 seconds is configured to prevent tempering or annealing from occurring in the can.

6. Using the first array of semiconductor-based narrowband irradiation devices located at the first station, irradiates and dries cans through a mesh belt or open-space belt of a collective conveyor, or irradiates and dries individual cans on a series conveyor. Using a second array of semiconductor-based narrowband irradiation devices located in a second station after the ink decorator, the ink applied to the outside of cans being transported on the conveyor belt is irradiated and cured, and This includes using a third array of semiconductor-based narrowband irradiation devices located in the third station to individually electrically heat the inner surface of each can that has moved into the curing zone, using optical elements positioned outside the can's open end, thereby bringing the paint on the inner surface of each can in the series-connected production cans to a critical temperature at which a linking curing process occurs in the paint, Each of these three stations performs a drying or curing function in less than 20 seconds to prevent tempering or annealing of the cans. A method for use in the manufacture of cans, for cleaning, decorating, and / or spraying paint onto the inside of a can.

7. The method according to claim 6, wherein ink curing occurs in less than 15 seconds, less than 10 seconds, or less than 5 seconds.

8. The method according to claim 6, wherein the inner coating reaches a critical temperature for linking or cross-linking in less than 10 seconds, less than 5 seconds, or less than 2 seconds.

9. Including the first station, The first station includes a first array of semiconductor-based narrowband irradiation devices arranged to irradiate and dry cans through a mesh belt or open-space belt of a collective transport conveyor, The first array is positioned within the housing and facing the inside of the can. The housing has a protective window that is sealed and positioned to prevent moisture from entering the array housing. The protective window is optically transparent at the applicable wavelength. The first array is provided with at least one reflective baffle for guiding the irradiation toward the can or an optical element for selectively widening or narrowing the beam of irradiation. It is configured so that the radiation does not escape from the system. A system for use in can manufacturing, for cleaning, decorating, and / or spraying paint onto the inside of cans.

10. The system according to claim 9, wherein the protective window is mounted at an angle to facilitate water drainage toward a trough or gutter located near the edge of the protective window, or is coated with an anti-reflective coating that functions in the narrow wavelength band to which it is applied.

11. The system according to claim 9, further comprising at least one fan or blower that provides a high-speed airflow to the mouth of the can in order to remove water vapor more efficiently.

12. Including the second station, The second station has a second array of semiconductor-based narrowband irradiation devices positioned to electrically heat the inner surface of each can that has moved into the curing zone individually using optical elements positioned outside the open end of the cans, so that the paint on the inner surface of each can in the series-connected production cans reaches a critical temperature that allows the paint linking curing process to proceed in less than 20 seconds, preventing tempering or annealing from occurring in the cans. The system according to claim 9.

13. Includes the first station, the second station, and corner cube reflective materials, The first station includes a first array of semiconductor-based narrowband irradiators arranged to irradiate and cure ink coated on the outer surface of cans being transported in a pin chain, the first array being positioned along the pin chain and configured to irradiate the outer surface of approaching cans at a first angle, The second station includes a second array of semiconductor-based narrowband irradiators positioned to irradiate and cure ink coated on the outer surface of cans being transported in a pin chain, the second array being positioned along the pin chain and configured to irradiate the outer surface of approaching cans at a second angle different from the first angle, The corner cube reflectors are positioned between the arrays at each station in a strategy that is substantially perpendicular to the tangent to the outer surface of the can, so that the illumination reflected from the outer surface of the can is subsequently reflected by the corner cube reflectors and returns substantially to a position on the outer surface of the can close to where it was first reflected. A system for use in can manufacturing, for cleaning, decorating, and / or spraying paint onto the inside of cans.

14. Including the third station, The third station has a third array of semiconductor-based narrowband irradiators arranged to individually electrically heat the inner surface of each can as it moves into the curing zone, using optical elements positioned outside the can's open end, and is configured so that the paint on the inner surface of each can in the series-connected production cans reaches a critical temperature that allows the paint linking curing process to proceed in less than 20 seconds, preventing tempering or annealing from occurring in the cans. The system according to claim 13.

15. Including several additional stations, Multiple additional stations include an array of semiconductor-based irradiation devices for irradiating and curing the ink coated on the outer surface of the can. Each array is arranged at an angle such that a combination of stations illuminates the entire outer surface of each can with ink. The system according to claim 13.

16. The system further includes a ventilation system for transporting vapor containing at least volatile organic compounds from the first and second stations to the pyrolysis or catalytic decomposition unit. The ventilation system is configured to maintain the steam at a threshold temperature, even at low levels. The system according to claim 13.

17. Further including drying stations, The drying station includes at least one array of semiconductor-based narrowband irradiation devices arranged to irradiate and dry cans through a mesh belt or open-space belt of a collective conveyor, or to irradiate and dry individual cans individually on a series conveyor. The drying station is designed to dry cans in less than 20 seconds. The system according to claim 13.

18. This includes a can handling system, an array of semiconductor-based narrowband irradiation devices, and a ventilation system. The can handling system is configured to sequentially move production cans to at least one curing zone. The array of semiconductor-based narrowband irradiation devices is configured to individually electrically heat the inner surface of each can as it moves into the curing zone, using optical elements positioned outside the can's open end, so that the paint on the inner surface of each can in the series-connected production cans reaches a critical temperature that allows the paint linking curing process to proceed in less than 20 seconds, preventing tempering or annealing from occurring in the cans. The ventilation system is configured to transport vapor containing at least volatile organic compounds to a thermal or catalytic decomposition unit and to maintain the vapor at a threshold temperature, even at a low level. A system used in can manufacturing that sprays paint onto the inside of a can and then cures the paint on the inside of the can.

19. Includes a can handling system, a broadband infrared source, and a ventilation system. The can handling system is configured to sequentially move production cans to at least one curing zone. The broadband infrared source is configured to individually electrically heat the inner surface of each can as it moves into the curing zone, using an optical element positioned to direct the irradiation towards the upper sidewall of the inner surface of the can, so that the paint on the inner surface of each can in the series of manufacturing cans reaches a critical temperature for the paint linking curing process to proceed in less than 20 seconds, preventing weakening, tempering, or annealing of the can body. The ventilation system is configured to transport vapor containing at least volatile organic compounds to a thermal or catalytic decomposition unit, and to maintain the vapor and outgassing compounds in the vapor at a minimum threshold temperature. A system used in can manufacturing that sprays paint onto the inside of a can and then cures the paint on the inside of the can.

20. Including the first and second stations, The first station includes multiple arrays of semiconductor-based narrowband irradiation devices arranged to irradiate and cure ink coated on the outside of cans being transported on a pin chain conveyor, the arrays of the first station are configured to cure the ink in less than 20 seconds, The second station includes a second configuration consisting of multiple arrays of semiconductor-based narrowband irradiation devices arranged to individually electrically heat the inner surface of each can that has moved into the curing zone using optical elements positioned outside the can's opening end, and is configured so that the paint on the inner surface of each can in the series-connected production cans reaches a critical temperature that allows the paint linking curing process to proceed in less than 20 seconds, preventing tempering or annealing from occurring in the cans. A system for use in can manufacturing, for cleaning, decorating, and / or spraying paint onto the inside of cans.

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