System and method for curing the interior of a can

Abstract

An improved inside-can curing technology is provided. One implementation uses semiconductor-generated narrow-band infrared energy. This infrared energy is focused inside the can, resulting in extremely fast curing. This focused, powerful radiant energy is used to directly affect the paint coating on the can's interior, rapidly curing the paint. Because the cure is so rapid, there is no time for tempering and annealing of the aluminum can body, resulting in a stronger can. This allows for the creation of stronger cans with the same amount of aluminum, or the creation of cans with the same strength using less aluminum. It also allows for the elimination of the current standard of natural gas-fueled ovens, replacing them with a completely hydrocarbon-free cure with superior performance. This powerful, narrow-band radiant energy is delivered directly to each individual can, rapidly curing the interior paint while being fully and dynamically digitally controlled to deliver only the necessary heat without overheating the can.

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 836,447, filed April 19, 2019, which is incorporated herein by reference in its entirety. [Background technology]

[0002] The process of manufacturing cans, such as two-piece aluminum or steel beverage cans, requires the application of a coating to prevent the raw aluminum or steel that makes up the can from coming into direct contact with the product that will ultimately be packed into the can. Some liquids can be ruined by contact with the aluminum material when packed into the can; other liquids can react chemically with the aluminum, compromising the integrity of the container. For example, beer is destroyed by even slight contact with raw aluminum. Soft drinks, on the other hand, are often acidic enough to chemically etch the already very thin aluminum surface, thereby compromising the strength and integrity of the can. Other products may be adversely affected by altered taste. Several processes are used to coat aluminum while it exists as cut-to-length flat or coiled stock before being formed into the final can shape. However, most coatings are applied after the raw flat or coiled stock is formed into the can shape through a forming process. There are currently two primary processes for the manufacture of food or beverage cans: the draw-redraw process (D&R) and the draw-iron process (D&I). The D&I process is sometimes called the draw-wall iron process, or DWI. Both processes produce a rolled cup from flat (usually) coiled stock. The cup is then further rolled to its final cup size. The second step in the D&I process involves successively "ironing" the cup walls until they reach the correct desired thickness and dimensions. A significant amount of engineering experimentation is required to develop the final shape of both the bottom and neck of the can during the process, and ultimately later in the process. It is crucial to achieve the correct geometric geometry so that the finished can can withstand the pressure exerted by the gases generated by the liquid food or beverage contained within the can. This structural shape is intended to sustain the pressure exerted along the sidewalls, but ultimately must prevent practical failure of the domed bottom, known as bottom inversion failure.

[0003] To explain in more detail, a typical draw-and-iron process (D&I or DWI) will be used as an example with reference to Figure 6. Figure 6 shows an example of a process 600 for forming a can using D&I. As shown, the can is shaped using an uncoiler (602), a lubricator (604), a copper (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 the cans are in the shape of straight-walled, neckless cans, they are washed using a washer (612) and dried at about 400°F, for example, using a gas dryer oven (614), and then they are put through a coating process, which includes an interior coating process.

[0005] The coating process begins by applying an ink base coat to the outside of the can using a base coater (616), if desired, and then drying the applied base coat using an optional base coater oven (618), which operates at approximately 400°F. The can then passes through a decorator (620) to apply an ink pattern to the can's exterior, and then through a bottom coater (622), which applies a layer of protective paint to the bottom of the can. The can then passes through a deco oven (624), also operating at approximately 400°F, to dry the exterior coat.

[0006] Next, the interior coating process begins, coating the can's interior surface. This process typically involves a single-file of cans passing through an interior coater (626), either an indexing starwheel or a continuous-running starwheel, and a spray gun operating to coat the inside of the can. The spray gun is highly engineered to direct a very fine mist of wet paint onto the can so that all surfaces are covered. The can rotates under the spray gun during operation to ensure uniform coverage around the can's 360-degree circumference. Typically, the goal is for the can to rotate two to five times while the interior is being sprayed. When wet, the paint appears as a thin white paint that adheres to the entire inside surface of the can. The can rotates at high speed during the process, using centrifugal force to distribute the paint evenly. It is important to spray coat the aluminum or steel can stock at the correct thickness to ensure proper coverage. Coating that is too thin or too thick will not work properly. Coating that is too thick can result in dripping, thick areas, improper curing, and wasted paint. Immediately after the spray coating process, the cans must be thermally cured in an internal bake oven called IBO (628).

[0007] The line of cans emerging from the spray coater in single file is routed onto a mass conveyor, whose material handling groups the cans close together so they can be nested dozens of times across a wide conveyor ranging from 30 to 80 inches wide. The conveyor belt that transports cans through the IBO (628) is designed to withstand the rigors of repeated high temperatures, allowing the belt material to safely pass through the oven and transport the cans to the curing oven. A passage through a curing oven typically takes 2 to 4 minutes. The oven typically has multiple heating sections through which cans pass sequentially. A typical IBO oven configuration involves introducing cans into the first section of the oven, where they are preheated to 200 to 270°F for approximately 60 seconds; section or zone 2, where the temperature is increased to 270 to 400°F for another approximately 60 seconds; and the final section or zone 3, where the temperature is typically held at 380 to 450°F for a final 60-second cure. Cans spend a total of approximately 180 seconds in the oven. While the duration of the thermal history may vary slightly, this is representative of conventional conditions.

[0008] When bulk cans exit the IBO, if they are properly cured, the epoxy coating on the inside should appear virtually transparent. While transparency is an indicator, it does not guarantee that the coating is fully cured. Laboratory testing is required to be certain. The IBO concept involves gradually increasing the temperature of bulk cans to the full cure temperature and then ensuring that they are held at 380-450°F for at least a minimum number of seconds. This is the time required for the epoxy coating to initiate the bonding or crosslinking process necessary for proper full curing. Once initiated by this "time at temperature," this crosslinking process continues until fully cured if the temperature is actually held above 375°F for the specified time. As mentioned above, a "clear" compound does not mean it is properly cured. If a slightly lower temperature is applied at that point, the compound will become clear even if the correct crosslinking temperature has not been initiated. Excessive curing is possible, and if the temperature is too high or the hold time is too long, the coating will turn yellow or blister. For example, holding a coated can at high temperature for 15 minutes will result in visible yellowing and blistering, which is clearly not an acceptable result of curing. This typically occurs when the oven conveyor stops for some reason while a large number of cans remain in the oven. For a typical beverage can, the total weight of the interior coating that needs to be properly cured is 80-150 mg.

[0009] After the cans exit the IBO (628), they are sent to a waxer (630) for further processing. After processing through the waxer is complete, a necker (632) and flanger (634) are utilized to complete the can forming process, as will be understood by 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 safe packaging of food and beverages in two-piece cans. The same or very similar processes are often used for other types of cans.

[0011] However, current IBO ovens, in particular, use an incredible amount of energy. Most ovens are natural gas-fired, although some are electric. Both types use significant amounts of energy and occupy large amounts of floor space. Because the can-box conveyor belt must pass through the oven and be subjected to continuous high / low temperature cycles 24 hours a day, 7 days a week, the ovens require extensive maintenance. Bearings, drivetrains, guides, and the belt material itself are all subject to continuous thermal and mechanical wear. Furthermore, given the fossil fuels that ovens typically use for energy, the use of IBO ovens raises sustainability and air pollution concerns. Furthermore, five large electric motors, totaling approximately 95 HP, are typically required to run the belt and to keep ventilating, exhausting, and scrubbing the air that enters the oven.

[0012] It is well known in the can-making industry that the aluminum that makes up the can actually loses strength due to the time spent in IBO. It is widely recognized that the can is only exposed to high temperatures for 2-3 minutes, allowing the tempering / annealing effect to occur and reducing the strength of 3004 aluminum alloy. Normal annealing takes significantly longer than these times, but because the aluminum is so thin, complete heat penetration occurs and begins to affect the grain structure virtually immediately, so annealing is considered to be occurring substantially in the can body.

[0013] Even with this tempering / annealing effect, cans must be manufactured to be actually stronger than the final specification. Approximately 8-10% of bottom inversion strength is lost as a result of passing through the IBO oven, so the can must have the bottom inversion strength necessary for proper performance. The pressure containment strength before "bottom inversion" must remain at 92-95 PSI for carbonated soft drinks and 105-110 PSI for beer. This high-speed softening, strength reduction, or annealing, has the effect of reducing the tensile and yield strength of the aluminum alloy, so the aluminum must be thicker to achieve the required strength compared to unannealed cans. Summary of the Invention

[0014] In one aspect of the present embodiment, a method for use in an interior coating and curing process in can manufacturing includes spraying a coating material onto an interior surface of a can; normally transporting the cans to at least one curing station; The coating on the inside surface of each can of a series of production cans is subjected to a crosslinking curing process of the coating. achievement Temperature west Less than 20 seconds And to bring the temperature below that within a time that can prevent tempering or annealing from occurring in the can. individually and electrically heated using narrow band radiant infrared energy elements and optical elements located on the exterior of each can in at least one curing station. (Hereinafter, this may be referred to as high-speed curing.) Includes:

[0015] In another aspect of this embodiment, each can is formed with manufacturing tooling that has been reconfigured to reduce the diameter of the cut edge of the blank from which the starting cup of the can is drawn, thereby reducing the width of the coil stock aluminum while maintaining substantially the same thickness as before the manufacturing tooling reconfiguration, thereby reducing the weight of aluminum required to produce each can by 3% or more.

[0016] In another aspect of this embodiment, each can is formed using a can design and tooling that has been modified to produce the can from thinner coil stock material to reduce the aluminum used to manufacture the can, thereby reducing can strength degradation due to heating to achieve a crosslinking curing process of less than 20 seconds, and each can has equivalent sidewall axial strength, bottom inversion strength, and overall strength compared to thicker cans that are cured for longer periods that weaken the metal.

[0017] In another aspect of the present embodiment, electrical curing of the paint is implemented by a narrow band semiconductor-based radiant heating system.

[0018] In another aspect of the present embodiment, 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 curing temperatures in less than 10 seconds.

[0019] In another aspect of the present embodiment, a conveyor transports the cans during the curing process and utilizes continuous rotational motion, whereby at least one irradiation curing station is in continuous rotational motion synchronous with the cans being cured, and at least one of electrical power, coolant, and control signals are connected to the at least one curing station via a rotary union.

[0020] In another aspect of the present embodiment, at least one of the DC power supply, refrigeration heat exchanger, refrigeration chiller, refrigeration recirculation pump, and control system provided to at least one curing station moves in a rotational motion synchronously with the cans to provide a continuous rotational motion curing system, where the continuous motion of the system serves the cooling function.

[0021] In another aspect of this embodiment, a conveyor transports cans during the curing process and utilizes a rotational motion for indexing. This allows multiple radiation curing stations to be located around, but not on, the turret, so that a group of cans is loaded sequentially into a selected number of empty stations around the turret. While the turret is rotating and indexing, cans are positioned under each narrow-band curing station, which operates to cure the cans, and then the turret is again rotating and indexing. This allows the cured cans to be removed, a new set of cans to be indexed into position under the curing stations for curing, and the process repeats.

[0022] In another aspect of the present embodiment, the cans are individually cured in less than 5 seconds.

[0023] In another aspect of the present embodiment, the narrowband semiconductor device emits narrowband radiant infrared energy at a wavelength that matches the absorption characteristics of the paint applied to the interior surface of each successive can.

[0024] In another aspect of the present embodiment, the wavelength of the narrowband radiant infrared energy used for heating is in one of the following ranges: 800 nm to 1200 nm, 1400 nm to 1600 nm, and 1850 nm to 2000 nm.

[0025] In another aspect of the present embodiment, the narrowband infrared radiant energy used for heating is generated using at least one of a semiconductor-based illumination device, a light emitting diode (LED), and a laser diode.

[0026] In another aspect of an embodiment herein, the illumination-producing semiconductor device is configured in a multi-device array where the combined optical output power of more than 10 individual semiconductor devices produces a total optical output power of more than 100 watts.

[0027] In another aspect of the present embodiment, the semiconductor device is a laser diode having a full width at half maximum output power of less than 20 nanometers.

[0028] In another aspect of the present embodiment, the semiconductor device is a surface-emitting laser diode having a full width at half maximum output power of less than 2 nanometers.

[0029] In another aspect of the present embodiment, the energy source comprises an array of surface emitting laser diodes that produce photonic energy output between 825 and 1075 nanometers.

[0030] In another aspect of the present embodiment, material / can handling is capable of individually curing a lane of cans at production rates exceeding 300 cans per minute.

[0031] In another aspect of this embodiment, multiple parallel curing stations are arranged so that all but one lane is operational, curing individually at a total throughput rate of over 1800 cans per minute, with the unused lane available for any maintenance that may be required or for additional production as needed, thereby achieving a higher level of uptime overall.

[0032] In another aspect of the present embodiment, the method saves over 3% aluminum in the can manufacturing process as a result of rapid curing in less than 20 seconds, without the use of hydrocarbon-based fuels, eliminating the annealing and weakening of the aluminum that makes up the can.

[0033] In another aspect of the present embodiment, certain additives are added to the coating to interact specifically with narrow band infrared light to enhance the performance or functionality of the cured coating.

[0034] In another aspect of the present embodiment, the method allows for the reformulation of paints to eliminate BPA or other undesirable components from current paint formulations.

[0035] In another aspect of the present embodiment, the curing method equipment configuration can be easily started and stopped without adversely affecting the can or the manufacturing process.

[0036] Another aspect of the present embodiments is the implementation of the ability to respond instantaneously to modulation of the method during operation as a result of sensory information obtained from the inspection system.

[0037] In another aspect of an embodiment herein, a system for use in an interior coating and curing process in can manufacturing includes a can handling system configured to sequentially move production cans through at least one curing zone, where a coating material is sprayed onto the interior surface of the cans, and an array of semiconductor-based narrowband irradiation devices positioned to individually electrically heat the interior surface of each can as each can moves through the curing zone using optical elements positioned outside the open end of the can to apply the coating material applied to the interior surface of each successive can in the series of production cans. Applicable paint of Crosslinking Curing Process can be achieved To temperature and below that temperature for less than 20 seconds and within a time sufficient to prevent tempering or annealing from occurring in the can. do.

[0038] In another aspect of an embodiment herein, an array of semiconductor-based narrowband illumination devices and optical elements are positioned just outside the top plane of the cut edge of the can to direct and cure 90% or more of the narrowband infrared photonic energy generated by the semiconductor-based narrowband illumination devices into the interior of the can, concentrating most of that energy in the top half of the sidewall and exposing the lower part of the can through internal reflection.

[0039] In another aspect of this embodiment, the optical element includes at least one microlens array aligned with each device in the array of semiconductor-based narrowband irradiation devices to form a column of energy, a focusing lens configured to focus the column of energy toward and through a pinhole or aperture into the interior of the can to be cured, and the pinhole or aperture providing an opening through a vertex of a reflective, designed-shape surface that functions to return narrowband energy escaping from the can back into the can.

[0040] In another aspect of the present embodiment, the reflective conical surface is equipped with ventilation slots or openings to facilitate removal of vapors from the curing can.

[0041] In another aspect of the present embodiment, the reflective engineered surface is generally conical and made from one of copper, aluminum, gold-plated metal, silver-plated material, and highly reflective nanostructures.

[0042] In another aspect of the present embodiment, the optical element and the array of semiconductor-based narrowband illumination devices are mounted in a housing configured to prevent stray infrared energy from escaping the housing except through a pinhole or aperture, and includes a recirculating water cooling system to maintain the array and optical element at an acceptable operating temperature in a production curing environment.

[0043] In another aspect of the present embodiment, the array of semiconductor-based narrowband irradiation devices includes at least one array of laser diodes positioned outside the cans, with corresponding optics articulated inside each can during at least a portion of the curing operation.

[0044] In another aspect of the present embodiment, the optical element includes an objective lens configured to receive energy from an array of semiconductor-based narrowband illumination devices via an optical system and mirror assembly. The system further includes an insertion and extraction mechanism for translating the optical element into the can via a reflection containment plate. The reflection containment plate is configured to be positioned over each can such that when a portion of the optical system assembly is positioned inside the can via the insertion mechanism, the optical transmission of energy is aligned, allowing illumination to be activated when the optical train is properly positioned inside the container to be cured.

[0045] In another aspect of an embodiment herein, a system for use in the manufacture of cans or containers for curing paint sprayed on the interior walls of the containers includes: an ingoing trackwork or conveyor configured to systematically or smoothly move individual containers sequentially in single file toward a second conveyor; the second conveyor configured as a rotating turret for moving the individual containers into and out of at least one curing station; and at least one curing station including an optical configuration in which photonic energy from at least one of an array of surface emitting laser diodes passes through column optics and is then focused by at least one focusing lens element onto a pinhole or aperture beyond which the photonic energy diverges to illuminate the inside of the sidewall of the coated container, the pinhole or aperture being located at the apex of a reflection cone that functions to reflect the photonic energy back into the container for further curing. Paint lasts less than 20 seconds And within a time that can prevent weakening or annealing from occurring in the aluminum that makes up the container. Curing with achievedThe second conveyor delivers the containers and directs them to a third conveyor configured to remove the containers from the second conveyor, with empty pockets being used to load uncured cans waiting to continue the curing sequence, and the cured containers being transferred to subsequent container manufacturing operations on the third conveyor.

[0046] In another aspect of this embodiment, the subsequent container manufacturing operation includes an inspection station located on the third conveyor that performs at least imaging and locating bare metal areas within each container to verify coating and curing accuracy to the extent that the cured coating has an insufficient quality level based on the images, and a reject station located on the third conveyor after the inspection station that rejects containers with defective coatings and then sends a signal to at least one of the coating system control system and the curing control system to correct the respective processes.

[0047] In another aspect of an embodiment herein, a system for use in the manufacture of cans or open-top containers for curing paint sprayed on the interior surface of the container includes: an input trackwork or conveyor configured to move individual containers in single file toward a second conveyor; the second conveyor configured to move the individual containers into and out of a curing station at least once using a rotary motion table; and at least one curing station incorporating one of a reflector designed to redirect photonic energy from the array, through an opening in the top (open top) of the container, and directly onto the paint sprayed on the interior surface of the container to aid in the curing process. The paint can be cured in less than 20 seconds. And within a time that can prevent weakening or annealing from occurring in the aluminum that makes up the container. Curing achievedThe second conveyor is configured to rotate to continuously load new uncured cans into vacant locations while discharging cured containers onto a third conveyor, which is configured to receive the cured containers and transport them to the next container manufacturing operation.

[0048] In another aspect of the present embodiment, the second conveyor is in a rotating configuration with multiple curing stations arranged around its periphery, each curing station operable simultaneously to cure the interior of the container with infrared energy generated by at least one laser diode array.

[0049] In another aspect of the present embodiment, the plurality of curing stations includes more than eight curing stations.

[0050] In another aspect of the present embodiment, the second conveyor is in a rotating configuration having multiple curing stations that rotate synchronously with the containers, allowing curing to continue without starting or stopping the table rotation, and at least one of power, cooling, and control signals are associated with the curing stations via at least one rotary union.

[0051] In another aspect of the present embodiment, the input trackwork or conveyor is configured to use gravity to advance the containers in single file and to use gravity pressure to feed individual cans to a second conveyor.

[0052] In another aspect of an embodiment herein, a system for use in an interior coating and curing process in can manufacturing includes a can handling system configured to spray paint onto the interior surfaces of manufacturing cans and to move the manufacturing cans sequentially through at least one curing zone; and a can handling system configured to apply paint to the interior surfaces of each successive can in the series of manufacturing cans moving through the curing zone using an optical element positioned to individually electrically heat the interior surfaces of the cans and to direct light toward an upper sidewall of the interior surfaces of the cans; Applicable paint of Crosslinking Curing Process can be achieved To temperature and below that temperature for less than 20 seconds and within a time sufficient to prevent tempering or annealing from occurring in the can. and a control system configured to use the sensor information to modulate the output of the broadband infrared source to maintain a consistent curing temperature and result. [Brief explanation of the drawings]

[0053] [Figure 1] FIG. 1 shows an exemplary can that can be cured using embodiments herein. [Figure 2] FIG. 2 illustrates a system according to an embodiment of the present application. [Figure 3] FIG. 3 illustrates another system according to an embodiment of the present application. [Figure 4] FIG. 4 illustrates another system according to an embodiment of the present application. [Figure 5] FIG. 5 illustrates another system according to an embodiment of the present application. [Figure 6] FIG. 6 shows a flow chart illustrating an exemplary conventional method for forming a can. [Figure 7] FIG. 7 illustrates another system according to an embodiment of the present application. [Figure 8] FIG. 8 illustrates another system according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0054] The embodiments herein teach an entirely new concept for curing paints on the interior surfaces of food, beverage, and other types of cans. According to the embodiments described herein, many of the implementations are suitable for replacing the conventional internal bake ovens (IBOs) mentioned above in connection with known techniques for forming cans.

[0055] One preferred implementation contemplates using narrow band, semiconductor generated infrared energy focused inside the can to effect very fast curing. It envisions the use of focused high-power radiant energy that directly impacts the paint and the inside sidewall of the can, rapidly transferring energy to both the paint material and the can wall, which then reflects and re-radiates back into the paint material. This intense radiated narrowband energy is introduced directly into each individual can and bounces around within the can at the speed of light until virtually all of the energy is absorbed by the paint and aluminum substrate.

[0056] While it is possible to provide the same amount of direct radiant energy to the interior of the can using a broadband light source, for many reasons, a narrowband light source is preferred and perhaps the most ideal solution. While broadband light sources such as quartz lamps could also be used, they offer fewer advantages and their implementation is less beneficial. However, it is possible to implement and practice embodiments herein using broadband light sources. For example, quartz lamps, high-intensity discharge, or arc lamps can be used. They tend to have wavelength output bands that are short enough to be focused by conventional glass optics. Conventional optical glass begins to become ineffective at wavelengths above about 2.7 microns, and most broadband light sources and the upper end of resistive heat sources will not pass through a focusing optic without heating the optic to excessive temperatures. Instead of focusing thermophotonic energy with refractive optics, a reflective optics configuration can be used. For example, a common conical reflector or an elliptical, circularly symmetric mirror can be used to focus infrared energy onto the inside of the upper sidewall of a can or container. This is the optimal area for the energy to strike the inside of the can, because internal reflections distribute the energy away from its preferred starting area. At the types of production rates we work with for can coating and curing, the various broadband light sources would almost certainly be switched on continuously, since they cannot be switched on and off at the kind of speed required for that application. While switching on and off is possible, equipping such a system with switching electronics to handle, for example, the 2000-3000 watt quartz bulbs required at each curing station would be expensive. The cans are heated to the temperature required to achieve the crosslinking curing action, but great care must be taken to ensure they do not become so hot that the aluminum body that makes up the can is annealed. Close monitoring of the can temperature and the ability of the electronic controls to modulate the output of the broadband devices would be highly desirable.One of the fundamental advantages of the present invention is that it eliminates the weakening effects of aluminum, facilitates the lightweighting of aluminum, and facilitates the production of cans of comparable strength to those obtained from conventional processes currently in near-universal use in the global can industry. Another consideration with broadband light sources is that they inherently have a shorter useful life than the semiconductor devices used in narrowband light sources. For example, quartz lamps have a short lifespan, but as they wear out, their light output continues to decline. Electronics can up-modulate to continually offset this decline in output. Monitoring sensors can be used with narrowband devices to establish feedback on can temperature and provide curing integrity.

[0057] Narrowband light sources can be implemented in a variety of ways, including high-power lasers, various semiconductor-based illumination devices; laser diodes; edge-emitting laser diodes; VCSEL laser diodes; surface-emitting laser diodes, including SE-DFB laser diodes; laser arrays; and light-emitting diodes (LEDs), such as high-power LED arrays. Multiple device arrays (e.g., more than 10 devices in an array) can be used to generate output power (e.g., greater than 100 watts). While the embodiments described herein can be implemented in other configurations, a high-power laser diode array is a preferred implementation due to ease and effectiveness of implementation. Additionally, various examples and implementations of narrowband light sources or arrays thereof, including semiconductor narrowband infrared sources or semiconductor narrowband infrared source arrays such as laser diode arrays, are described, for example, in U.S. Application No. 11 / 003,679, filed December 3, 2004 (now U.S. Patent No. 7,425,296), U.S. Application No. 12 / 718,899, filed March 5, 2010 (now U.S. Publication No. 2011 / 0002677 A1), and U.S. Patent Application No. 12 / 718,919, filed March 5, 2010 (now U.S. Patent No. 9,282,851), all of which are incorporated herein by reference.

[0058] Narrowband energy also allows for better optical precision because the wavelengths are close enough to be focused almost perfectly, something that broadband sources cannot do. In some implementations, optical coatings, such as anti-reflection coatings, can be optimized to be highly efficient at the specific wavelength or narrow range of wavelengths being used.

[0059] Because laser diode arrays can be digitally switched and can be rapidly switched on and off, this will facilitate a wide variety of possible implementations of the embodiments described herein. Laser diode arrays can also be configured to be optically manipulated in many convenient ways to facilitate directing the appropriate energy to the can in the precise areas necessary for effective implementation of high-speed curing. This application teaches several possible example optical implementations and several mechanical implementations for can handling, depending on the exact application and preferences of the implementer of the embodiments described herein.

[0060] If the embodiments described herein are effectively implemented, they could potentially affect a system that cures the paint inside a can in as little as one second. If the paint is formulated to initiate the crosslinking process quickly enough, sufficient power from the radiation source could even achieve curing in less than one second. It should be appreciated that shortening the curing time compared to conventional methods improves overall efficiency, benefits, and results. In particular, the improvement increases substantially as the curing time decreases, for example, to less than one minute. By way of further example, curing times of less than 30 seconds, less than 20 seconds, less than 10 seconds, less than 5 seconds, and (as noted above) less than one second provide even greater improvements. If the curing time is sufficiently short, for example, less than 20 seconds in at least one embodiment, or, by way of further example, less than 30 seconds in at least another embodiment, can annealing is prevented. Shorter curing times (e.g., less than 10 seconds, less than 5 seconds, or less than one second) similarly result in avoidance of annealing. If the annealing effect can be prevented, cans would not need to be over-strengthened to maintain sufficient residual strength after the curing process. This could be a significant advantage for can manufacturers, since approximately 70% of the equipment and manufacturing costs for an average can are the cost of the aluminum material used to make the can. Eliminating the need to over-strengthen cans by 8-10% would result in significant material savings, and therefore cost savings. Until now, manufacturers have not considered rapid curing at production speeds as a means to eliminate the need to over-strengthen cans. This is an entirely new concept. Previous approaches have not been able to cure at such rapid rates, forcing manufacturers to consistently over-strengthen cans to maintain sufficient strength. Cans have historically been cured in bulk shipments. The embodiments described herein introduce high-speed, narrow-band curing of individual cans.

[0061] It is useful to outline the many benefits that result from proper implementation of the embodiments described herein. Reducing the amount of material is a significant advantage in can manufacturing. To save money, one might consider replacing the highly alloyed aluminum currently used with less alloyed aluminum, which is available at a lower cost. A further advantage of the embodiments described herein is that the width of the aluminum coil stock can be narrowed because the diameter of the rolled cup is reduced and the cut edge length is shortened. The reduced width means that the cost of feeding and coil handling equipment is reduced and its reliability is increased. It also means that narrower-bed, double-action stamping presses can be purchased and implemented, allowing for the use of smaller, lighter, and faster press tooling. A narrower press bed means a stiffer machine and less moving mass, resulting in longer press life and longer tooling life. Cup tooling for making smaller diameter cups requires a lower initial investment and, because of the smaller diameter and less steel required for the tooling, replacement tooling components are also less expensive. Another advantage is that the embodiments described herein facilitate the modification and precise adjustment of curing parameters, for example, by using a digital narrowband curing system, to improve or optimize the level and overall curing process. A further advantage is that this adjustment can be performed dynamically to fully accommodate selected production rates and achieve improved or optimized energy savings. A closed-loop process can also be developed, verifying the accuracy of the curing and correcting any under- or over-curing that may occur. Additionally, verifying the curing in real time, such as with machine vision inspection or laser scanning, can optimize the amount of curing energy. This can be used to further save energy by not injecting more joules of energy into the can than would actually be required for proper curing.A further advantage is that the embodiments described herein, in some embodiments, allow for the incorporation of additives into coatings that more easily and optimally absorb at selected wavelengths, thereby paving the way for even lower energy curing and potentially higher throughput speeds. The embodiments described herein have the additional advantage of facilitating tremendous energy savings. A still further advantage is the substantial or complete elimination of hydrocarbon or fossil fuel use in the curing process. A still further advantage results from cans curing more uniformly within themselves and relative to other surrounding cans. Another advantage is the ability of the system to quickly stop and start a production line with minimal adverse consequences. A similar advantage is the elimination of the need for preheating before starting a production line, whether from a cold or warm line after a shutdown. A related advantage is the elimination of the need to clean ovens and discard cans as a result of unscheduled shutdowns, power outages, etc. Other quality advantages result from more informal line shutdowns without such adverse consequences. This is a shutdown method avoided by current technology users due to fear of such harmful consequences. Further benefits result from the elimination of unnecessary extra plant heating around the IBO oven, which reduces the need for extra plant cooling and air conditioning in various climates. Additional benefits include the reduction or elimination of hydrocarbon-based fuel use. Yet another advantage of the embodiments described herein is the ability to very quickly and completely switch from one can type to another under programmable control. Yet another advantage arises from the ability to independently service individual single-file curing lanes, allowing one curing portion of the line to continue operating while the rest of the line is serviced. This provides the added benefit of more continuous operation, eliminating the need for periodic shutdowns for oven maintenance.Ultimately, this should increase production throughput and reduce downtime.

[0062] Referring now to the drawings, the narrowband, high speed, inside-can curing techniques described in connection with embodiments of the present invention can be implemented in several different ways. The various methods for implementing the exemplary embodiments described herein primarily relate to two general areas: first, how to position the system to move the can in and out of the narrowband irradiation source; and second, how to generate and target the narrowband irradiation specifically to the desired area inside the can.

[0063] According to the embodiments described herein, a two-piece beverage can with an interior cured coating is typically one commonly known in the industry and includes the sections described below, as shown in FIG. 1 . While other shapes and configurations, such as cans with tapered walls, cans generally can be cured, most two-piece cans remain in the configuration detailed here for instructional purposes regarding the practice of the embodiments described herein. In this regard, the can (22) has a straight, vertical wall (23) extending from the can's moat (26) and heel (25) to the top of the can. The top of the neckless, straight-walled can (22) is typically referred to as the trimmed edge or trim edge (21). Interior coating and subsequent curing operations are typically performed on the straight-walled, neckless can (22). A neck and flange are formed in the area near the trim edge by a subsequent operation using a necker / flanger machine. The bottom of the can (22) has a contoured area starting from the bottom of the wall (23), called the heel (25), transitioning into a moat area (26), and then finally into an arched dome area (24) at the bottom center of the can (22). These various sections of the can (22) are designed and thoroughly tested to withstand the pressures required for soft drink or beer containers (pressure ranges generally between 90 and 110 PSI). The base metal (28) for fabricating the entire body of the can (22) is most typically aluminum alloy #3004. This alloy has a balanced combination of strength, formability, and resilience for can manufacturing processes and can applications, making it the alloy of choice and standard across most industries. Admittedly, this alloy is more expensive than straight aluminum. Anything that can be done to enable the production of fully functional cans from lower-alloy materials will save manufacturers money.

[0064] The exterior surface of the can (22) is typically coated or printed with a layer of paint or ink (29), as shown. Current industry practice is to coat the entire interior surface of the can (22) with a layer, such as layer (27) of epoxy-based material, which is baked and properly cured. Industry specifications for a properly cured coating are actually well-known within the industry and are part of manufacturers' specifications. Of course, it is completely unacceptable to have any areas on the inside of a can that are not coated or properly cured. The can manufacturing industry is always concerned with ensuring that all paints are properly cured and that there are no void areas in the finished product, which are areas of uncured epoxy. Coatings other than epoxy have been experimented with but have not been widely deployed. If other types of coatings or partial coatings require heat or thermal curing, the embodiments described herein are also highly effective. The embodiments described herein may also be applied to new coatings that reduce or eliminate BPA in thermally cured coatings.

[0065] While there are two primary areas requiring design attention, the first challenge facing practitioners of the embodiments described herein is how to generate powerful narrowband irradiation. A designer's initial impulse is to construct something that can be inserted into a can, irradiating it in multiple directions, if not a 360° pattern. While this is possible, most available technologies for generating high-power narrowband energy are significantly larger than what can be inserted into the neckless top of a beverage can. As technology advances and narrowband energy devices generate more power more efficiently and in smaller packages, this could certainly become more practical. Regardless of the size of the energy-generating device, the problem with "inserting into a can" technology is that it involves many moving parts and mechanisms. The insertion / withdrawal motion must occur at between 200 and 400 strokes per minute, a speed requirement that may increase in the future. This assumes that the overall production flow through a can manufacturing line is divided into six to eight curing lanes, each running at a throughput rate of 200 to 400 cans per minute. In this regard, for example, a typical production rate can be about 300 cans per minute or more. Nevertheless, the concept of inserting and extracting the irradiation source into and from the can is a viable implementation technique, but it would require more mechanisms to insert and extract the irradiation source device at this high rate, which would be more complex than a non-articulating device that does not enter through the opening face of the can body, and therefore would be expected to require more maintenance.

[0066] Instead of inserting and removing an actual source of narrowband radiation, it is possible to insert and remove optics or some form of light guide to direct the narrowband radiation 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 light sources and deliver it to the can. For example, if a single, very high-power laser is used to provide the narrowband radiant energy, the fiber optic light guide can be coupled in a location safely away from the rigors, vibrations, and contaminants of the actual curing station. The correct lens or diffusion must be designed at the exit end of the fiber optic light guide to produce an output pattern that properly illuminates the paint applied to the inside of the can.

[0067] The light guide can take the form of a lens arrangement (see Figure 3) positioned to collect narrowband energy near the light source (32), then project it through a final objective lens arrangement (38) and a mirror assembly (34) that is at the correct focal length when the articulation mechanism (33) is fully inserted into the can (22) for illumination. The photonic energy (30) can then be directed down a tube (35) to the output of the objective lens (38) within the can (22), possibly in combination with an additional diffuser (37), and then directly onto the paint (27) inside the can. Many different arrangements of lens and light guide-type approaches can be constructed by those skilled in the art of high-energy lens and optical design. The vertical insertion and extraction mechanism (33) ideally has a containment reflector plate arrangement (36) to reflect the energy back into the can, thereby maintaining the photonic energy within the can. Ensuring that all illumination is delivered to the interior of the can also makes the arrangement safer. All components and mechanisms must be designed to handle the rigors of high-speed loading and unloading to meet high-productivity manufacturing requirements. While this methodology may prove to be a superior method for delivering a uniform illumination pattern to the inside of a can, it requires significant effort in terms of articulation mechanisms and engineering, and is therefore more costly to implement. It has the distinct advantage of providing a very direct method for projecting narrowband illumination onto a coated surface for superior results. It has the disadvantage of placing an obstacle (35) in the can that blocks a portion of the reflected energy (39), which must continue to strike the coated surface until its energy is depleted. While the reflector (35) itself could be used as a reflector, some of the energy (30) would be lost and wasted during reflection off the uncoated surface. It also adds significant heat to the optical assembly (35) and (34), which must be addressed and removed.

[0068] Another technique for providing irradiation energy to the inside of a can (22) is shown in Figure 2. This is based on a design concept in which no components protrude into the can's interior and penetrate the trim edge (21). It is envisioned that the irradiation mechanism does not need to articulate in or out of the can, but can be fixed in some manner directly above the can and still provide sufficient and appropriately distributed irradiation within the can. In this regard, an optical system can be incorporated into and / or used in conjunction with the irradiation system. A properly designed light irradiation system, at least in some embodiments, will be able to focus a relatively high percentage of light energy—e.g., 95% or more, or even 90% or more—that emerges directly and uniformly from the optical configuration to the interior of the can for curing purposes. Because aluminum is highly reflective at these infrared wavelengths and the can is cylindrical, many internal reflections can be expected. In most implementations, careful design is required to allow randomly reflected energy from the can's top opening to be reflected back into the can, continuing the process of internal reflection until the energy is depleted. Because infrared light energy travels at the speed of light, in the case of high-speed curing, many reflections can occur within an exposure time of a few seconds.

[0069] This configuration relies on the fact that aluminum exhibits high reflectivity not only in the visible and near-infrared, but also in the short-wave infrared bands. If the bottom surface of the narrowband irradiation assembly is positioned, for example, about 0.030 to 0.045 inches from the top trim edge of the can (21), that is close enough to avoid excessive energy loss through the gap, and close enough to allow good enough energy transfer at the angle required to efficiently cure the paint by bouncing the energy around inside the can. The conical or cone-like surface (64) must match the interior geometry of the can and be close enough to allow a majority of the reflected energy from the top opening of the can to be returned into the can. The conical surface can be formed from a variety of different materials, including copper, aluminum, gold-plated metal, silver-plated metal, and / or highly reflective nanostructured materials.

[0070] The embodiment shown in Figure 2 can also be modified. In this regard, referring to Figure 7, the reflective cone (64), or any selected geometric shape, should in most embodiments optimally ventilate water vapor from the can by positioning the louvers accordingly. The louvers (74) are preferably shaped to be reflective facing the interior of the can, but with spaces between them to provide for vacuum-creating airflow through the vacuum port (72). A properly designed airflow system can actually pull vapor-laden air out of the can through the louvers (74) or reflective cone ventilation holes, rather than just forcing air into the can.

[0071] For example, if the interior geometry of the cone (64) is designed with a 90° included angle (69), it acts as an excellent multi-angle reflector, reflecting narrowband energy back into the can for further curing. Depending on the wavelength selected, the energy can bounce hundreds or thousands of times inside the can until all of the energy is absorbed by the paint (27) or the aluminum (28) that makes up the substrate.

[0072] The primary purpose of the optical arrangement shown in Figure 2 (or Figure 7) is to inject photonic energy into the interior of the can 22 as shown. In one example, narrowband photonic radiation energy is generated in an array 51 located on top of the one depicted in Figure 2. An array or arrays 51 can have any number of laser diodes connected to an appropriate power supply. Array designers can use a combination of serial and / or parallel connections of laser diode devices to achieve the desired current and voltage input settings for their system. This determines the current capacity and voltage required for the power supply. Selecting the appropriate combination allows for optimization of the power supply specifications. Laser diodes can be designed as edge-emitting or surface-emitting types. Surface-emitting designs offer substantial ruggedness advantages, as the active aperture is much larger and therefore less susceptible to damage from contaminants. Traditional edge-emitting designs are most often coupled to fiber optic light guides, providing a better way to deliver narrowband energy to the optical train without exposing the rather fragile aperture to harsh environments and contaminants that can cause catastrophic aperture failure. While traditional edge-emitting laser diodes are a viable solution for implementing the embodiments described herein, the additional costs and assembly complexity associated with fiber optic coupling to the device make them less desirable and significantly more expensive than other solutions. Surface-emitting laser diodes, on the other hand, often do not require fiber coupling. They can be configured to directly illuminate an optical configuration that typically directs their narrowband output directly into the can. This arrangement can sometimes be unstable due to its proximity to the curing location. However, eliminating fiber coupling can result in significant cost savings and increased reliability of the overall configuration. Regardless of which type of device is selected for an application, it must be mounted in a housing (55) such that its optical output is directed toward a focusing lens (56).In at least one embodiment, the housing is configured to prevent divergent infrared energy from escaping the housing except through a pinhole or appropriately sized aperture (described below), although various housing configurations can be implemented. The output of a laser diode can diverge in two directions, the fast and slow axes, or it can diverge in a single direction. In the case of SE-DFBs, the output is columnar in one direction and slowly diverges in the other. For SE-DFBs, the slow axis is considered the columnar direction, and the fast axis typically diverges by 7–10°. When using VCSELs as narrowband photonic energy generation devices, VCSELs have a conical output pattern. Regardless of the type of laser diode selected, multiple devices must be packaged and configured in an array to ensure their total output power is sufficient. SE-DFBs, VCSELs, and other surface-emitting devices can be packaged on a cooled circuit board in an X × Y or other pattern, with the energy directed approximately perpendicular to the mounting circuit board.

[0073] Arrays can certainly be of various sizes to implement the embodiments described herein. In at least some embodiments, arrays can be constructed and used for curing the interior of cans with a total output power ranging from 250 watts to over 500 watts. For example, a 500-watt array can be constructed with 50 surface-emitting laser diodes, each producing 10 watts of narrowband near-infrared light power. This may not be enough light power to cure the interior paint within a specified time, so a designer's best configuration may be to build multiple identical arrays. Testing has shown that a single 300-watt laser diode array can adequately cure a very thick layer of interior paint within 10 to 15 seconds without careful optimization of the optical configuration. An appropriate optical configuration, such as the example shown in Figure 2, can distribute photonic energy precisely where needed for improved uniformity and much faster curing. This optical configuration results in less wasted photonic energy and significantly reduced curing times. By combining the appropriate number and design of arrays, it is quite reasonable to achieve an improved (e.g., optimized) configuration that will cure the epoxy paint in an individual can in less than one second. It should be understood that, in at least some embodiments, the optical configuration can be designed or tailored to impart a desired amount of energy to a desired location inside the can. For example, an optical configuration can be implemented that imparts more energy to the top of the interior sidewall surface of the can and smoothly reduces the energy down the sidewall of the can. Various optical elements (e.g., refractive, reflective, nonlinear, aspherical, or other elements) can be used to achieve these and other objectives to suit the needs of a particular configuration.

[0074] In such an improved or optimized configuration, with continued reference to FIG. 2 (and FIG. 7), the optical system or microlens array (52) can be selected to generate a column of energy (54) directed parallel to the central optical axis of the system. When the column of energy is generated and directed toward the focusing lens (56), the output energy (57) converges toward a focal point at the pinhole (65), where the optical energy then intersects and becomes a diverging beam (58) as it travels toward the paint inside the can (22). The photonic energy first passes through the layer of paint (27) and, upon reaching the inner wall of the can, reflects off the inner wall of the can (28), causing the energy to pass through the paint (27) again. The photonic energy continues this process of traveling through the paint (27), bouncing off the wall (28), and traveling back through the paint (27) until all of the energy has been imparted to the paint and the can wall, as shown, for example, at (59). Some of these bounces strike the reflective cone surface 64 and bounce back into the can to continue the process. The cone surface 64 must be fabricated from or coated with a highly reflective material. This material can be copper, silver-coated, gold-coated, or other material that is as highly reflective as possible for the specific wavelength of infrared light being utilized. The pinholes 65 and 71 are located within the plate 62 and are designed to be replaceable, allowing for easy maintenance and maintaining a clean, sharp pinhole area. The pinhole size (3 mm, for example) and sidewall shape should be the smallest the optical configuration can accommodate, ensuring that substantially all of the focused photonic energy passes through the pinhole without imparting energy to the pinhole plate 62, but without creating unnecessarily large openings 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, a pinhole such as pinhole 65 may be adequately implemented for systems according to embodiments described herein that require more precise focusing of the illumination onto the inside of the can.However, such an arrangement (which may generate more heat and / or be more costly to implement) may not be necessary in all configurations. Therefore, any suitable size aperture, e.g., an aperture having a diameter smaller than the opening at the top of the can, may be implemented to achieve the desired results. In this regard, such apertures may be smaller than 2 inches, by way of example only, or other dimensions depending on the size of the can. The reflective structure (64), which can be formed in the optimal geometry to reflect energy back into the can, is also designed to be easily replaceable and refreshable, providing a clean reflective surface. It may also be designed for quick and easy replacement periodically as needed, with minimal tools. The angle of the reflective cone insert (64) should be carefully modeled to reflect the maximum amount of energy back into the can, taking into account the specific geometry of the can. The housing (55) should be made of a material capable of handling the diffuse reflection of the infrared radiation it contains. Cooling holes (61) are desirable throughout, allowing water or a coolant to circulate within the housing for constant cooling. This is necessary to keep the semiconductor device array (51) at a comfortable operating temperature so that it is not forced to operate in an ambient environment that is too warm. The laser diode array (51) also requires some form of cooling. They can be cooled by a circulating system of coolant that passes through the actual array. The coolant can be deionized water. In the most desirable implementation, it can be plain water circulated through the array. If the device efficiency is high, as it may be in the future, gas or liquid coolant may not be necessary; air cooling with a heat sink and fan can keep the device within a comfortable operating temperature range. The housing (55) can also have cooling facilities to ensure that none of the components mounted therein, including the optics and laser diode array, are subjected to excessive heat. Again, the cooling for the housing (66) can be a recirculating water jacket or a forced air cooling configuration.It should also be appreciated that the bottom surface 67, in at least one form, is configured to control the reflection of energy escaping from the interior of the can 22. As shown, the surface 67 includes grooves, e.g., deep grooves, to provide such control over escaping energy, although various configurations and / or techniques can be implemented to achieve this goal. Regardless of the configuration of the bottom surface 67, the flush mating surfaces at the front and rear of the housing 55 are preferably designed and constructed so that the incoming surface 73 is level with the furthest extent of the bottom surface 67 of the housing 55. The outgoing surface 72 is also preferably level with or slightly higher than the furthest extent of the bottom surface 67 of the housing 55 to prevent the top trim edge surface of the can 22 from encountering bumps.

[0075] These various technologies allow for the use of broadband infrared radiation sources such as quartz lamps or high-energy discharge lamps. However, precisely focusing the energy is more difficult. They cannot generate the most efficient wavelengths to match the paint for best and fastest curing with good energy efficiency. They also inherently get very hot due to the way they generate their output energy. This requires a lot more engineering to keep everything cool and not completely overheat the can. If the can is overheated, tempering or annealing cannot be eliminated, even for a short time. These broadband infrared sources offer less control over the heat they impart to the can and require modulating their output as a function of throughput speed. However, they cannot be switched on and off as quickly and precisely as semiconductor-based radiation, although this may be achievable with careful engineering. For example, as mentioned above, broadband electro-infrared components such as quartz lamps, high-intensity discharge lamps, or arc lamps can be utilized. Again, instead of focusing the thermophotonic energy with refractive optics, a reflective optics configuration can be used. For example, a properly designed reflector arrangement, typically a conical reflector, or an elliptical circularly symmetric mirror, can be used to focus infrared energy onto the inside of the upper sidewall of a can or container. This is the optimal area for the energy to strike the inside of the can, since internal reflection distributes the energy from its preferred starting area. In this regard, the configuration shown in FIG. 3 (and the configuration shown in FIG. 2) can be appropriately modified to implement a broadband embodiment, where the radiation source is implemented with a broadband source and the optical elements are implemented with reflective elements rather than refractive elements, and are positioned to direct or point radiation toward the inner surface of the upper sidewall of the can.

[0076] 8, there is representatively shown a broadband infrared system 200. The system 200 is for use in the manufacture of cans in an interior coating and curing process in which paint is sprayed onto the interior surfaces of the cans, and includes a can handling system 205 (not shown in detail) configured to continuously move the manufacturing cans through at least one curing zone. Additionally, system 200 includes a broadband infrared source 230, such as a quartz lamp 220, positioned to individually electrically heat the interior surface of each can 22 (shown in cross section) introduced into the curing zone using optical elements 240. Optical elements 240 (e.g., representatively shown at 260) are positioned to direct radiation toward the upper sidewall of the interior surface of the can, thereby curing the paint on the interior surface of each successive can in the series of production cans. Applicable Crosslinking curing process for paints can be achieved To temperature and below that temperature for less than 20 seconds and within a time sufficient to prevent tempering or annealing from occurring in the can. do. The system also includes a control system 210 (connected using link 250—which can take a variety of forms and is shown only representatively) configured to use sensor information (not shown) to modulate the output of the broadband infrared source to maintain consistent curing temperatures and results. While the configuration of such a system 200 may vary as shown, the optical element can take the form of a suitably designed reflector arrangement, a typical conical reflector, or an elliptical circularly symmetrical mirror, used to focus infrared energy onto the inside of the upper sidewall of the can or container 22, as described in the examples above. In at least one form, such optical element is sized at least slightly smaller than the diameter of the container or container opening, such as container 22, to allow for proper delivery of energy to the can and proper retention of that energy within the can for curing purposes.

[0077] However, as described herein, precise digital control and precise energy control favor semiconductor solutions. Semiconductor-based irradiation configurations have much longer lifespans and much more consistent output over their useful lives. Broadband sources have useful lives of thousands of hours, during which time their output continually degrades and must be carefully regulated to ensure consistent curing results. Because they do not all wear out at the same rate, ensuring that each lamp's irradiance output is sufficient to ensure proper curing is both an engineering challenge and a chronic maintenance issue.

[0078] 4 and 5, implementations of the embodiments described herein also address, in most forms, preferred configurations for mechanical handling of cans. These configurations come in at least four different forms. It should also be understood that the descriptions of FIGS. 4 and 5 include references to examples of narrowband illumination sources. However, broadband infrared sources and corresponding systems can also be used in these embodiments, with appropriate modifications, if desired.

[0079] Further, while example implementations are shown in Figures 4 and 5, implementations may take a variety of forms. Along these lines, methods and / or systems according to embodiments described herein may be implemented in can manufacturing in an interior coating and curing process in which paint is sprayed onto the interior surface of the cans. A can handling system (e.g., including a conveyor, which may take a variety of forms) continuously transports the cans toward at least one curing station. The cans are then cured, for example, using narrowband semiconductor elements (e.g., an array of semiconductor-based narrowband irradiators) and optical elements that generate radiant infrared energy and are positioned outside the cans in the at least one curing station to ensure that the paint on the interior surface of each successive can in a series of single-file production cans is Applicable The cross-linking curing process of the paint can be achieved. Warm every time Becoming Less than 20 seconds And keep it below that temperature within a time that will prevent tempering or annealing from occurring in the can. , individually and electrically heated. Thus, using this technology, cans can be made with less aluminum, e.g., 3% or more, compared to previous technology, and because thicker cans weaken during longer curing, the can has similar sidewall axial strength, bottom inversion strength, and overall strength compared to heavier cans that are cured for longer times. An exemplary embodiment also includes an input trackwork or conveyor configured to organize or facilitate the movement of individual containers sequentially in single file toward a second conveyor, said second conveyor configured as a rotating turret for moving individual containers into and out of at least one curing station, and at least one of said curing stations including an optical configuration in which photonic energy from at least one of an array of surface emitting laser diodes passes through a columnar optic and is then focused by at least one focusing lens element through a pinhole or aperture, beyond which the photonic energy diverges and is irradiated onto the interior sidewall of the coated container, said pinhole or aperture being located at the vertex of a reflection cone, which serves to reflect the photonic energy back into the container for further curing, and teeth Less than 20 seconds And within a time that can prevent weakening or annealing from occurring in the aluminum that makes up the container. Curing achieved A second conveyor then transports the containers and leads them to a third conveyor which takes them away from the second conveyor, and empty pockets are available for loading waiting green cans to continue the continuous curing, while the cured containers are transported by the third conveyor to subsequent container manufacturing operations. Further exemplary embodiments include an input trackwork or conveyor configured to organize or facilitate the movement of individual containers sequentially in single file toward a second conveyor; said second conveyor configured as a rotating turret for moving individual containers into and out of at least one curing station; at least one of said curing stations including an optical configuration in which light energy from at least one of an array of surface emitting laser diodes passes through a columnar optic and is then focused by at least one focusing lens element through a pinhole or aperture, beyond which the light energy diverges and is directed onto the interior sidewall of the coated container; such pinhole or aperture is located at the apex of a reflective cone, which operatively reflects the light energy back onto the container for further curing; teeth in less than 20 seconds And within a time that can prevent weakening or annealing from occurring in the aluminum that makes up the container. Curing achieved A second conveyor then transports the containers and leads them to a third conveyor which takes them away from the second conveyor, and empty pockets are available for loading waiting green cans to continue the continuous curing, while the cured containers are transported by the third conveyor to subsequent container manufacturing operations.

[0080] More specifically, referring back to the drawings, one example configuration outlined in connection with Figure 5 is a configuration involving continuous rotational motion. In this arrangement, the narrowband irradiation source (and possibly a controller), optics, cooling devices (such as a heat exchanger, chiller, and / or recirculation pump), and power source (such as a DC power supply) rotate with the starwheel. The starwheel organizes the cans into the correct spacing, provides the motive force to move the cans, and delivers the cans to the appropriate location for irradiation. The rotary union is designed into the system to provide the necessary power, control signals, compressed air, vacuum, and / or cooling for the continuously rotating turntable or turret. The premise here is that the narrowband irradiation array or narrowband irradiation source is configured to continuously irradiate the interior of the can through the optical configuration for the time required to provide sufficient Joule energy for complete curing. The entire irradiation system rotates clockwise in synchronization with the can. The irradiation energy is turned on as the can rotates through the starting irradiation station and turned off before the can exits the starwheel. As an example, if a particular narrowband irradiation system can produce 500 joules and 850 joules are required to properly cure a particular can, irradiation should be turned on for a 1.7-second portion of the starwheel arc. The start time and duration of irradiation on can be fixed or, more ideally, programmable parameters. The intensity or pulse width modulated when irradiation is on (duty cycle) should be at least some form of programmable. The user interface can be configured to meet the end customer's needs. It can be as simple as a screen entry on a programmable controller display or as complex as a PC-driven user interface with user-friendly graphics showing on / off timing, duration, and intensity. It can also facilitate programmability or graphical configuration of intensity curves as a function of time or turntable position.The system's controller can also communicate with portable devices such as tablets, smartphones, and smartwatches to provide highly convenient monitoring of the settings, speed, and functions of the curing system. The starwheel diameter and RPM must be configured to provide an adequate dwell period for irradiation to perform a proper cure. This configuration for the embodiments described herein is described in more detail below.

[0081] This narrowband radiation curing system is highly flexible and programmable, allowing it to be interfaced with other methods. A downstream inspection system (97) can inspect the outgoing cans (89) to ensure the paint covers the entire interior of the can and is fully and properly cured. This inspection system can use either a visible grayscale or color camera, an infrared camera on its way out of the curing system, or both. The inspection system can ultimately determine if there is bare, uncoated metal, or uncured paint. If the inspection system (97) does not determine that the paint is not properly cured, the system can create a closed loop and gradually increase the joules of energy being applied to various cans from each station to ensure they are curing correctly. The system can correlate to each other, knowing which cans were cured by which curing system (91). If cans from an individual curing station are not sufficiently cured, the system can correct by increasing the curing energy from that particular curing station. Similar process modifications by closing the loop from the inspection station back to a particular curing station can be achieved in any configuration in which the embodiments described herein can be implemented.

[0082] The system in Figure 5 functions as follows: Paint-sprayed, but uncured, cans (82) arrive, for example, on another conveyor or device via a conveyor, trackwork, or similar mechanism, or a system configured to organize or facilitate the sequential movement of individual containers in a single file. Such a conveyor can be any form of conveyor, including a vacuum conveyor, or simply trackwork that guides the cans as air or gravity pushes them along. Schematically shown is a vacuum belt-type conveyor (80) with guide trackwork (81) along both sides of the row of cans. The row of cans (82) is propelled forward by applying slight pressure to a holdout plate (87) when the next can to be loaded is on a 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 the cans are pushed into that pocket. As the cans are pushed into the pockets (86), they are assisted by a vacuum drawn from the rear of the nest holdout plate (87), the part of the turntable closest to the center. The holdout / nest plate must be carefully shaped so that the cans slide smoothly into the pockets (86) without denting or deforming them when the pockets open and become available. A designated location must also be prepared for the cans to hold and securely hold them in place while curing. As the turntable (84) continues to rotate, transporting the cans to the nest locations (86) and past the loading station, a signal is sent to turn on the irradiation energy. A control system switches on the energy so that the irradiation devices can be used for curing at a rate that is not so slow as to cause harmful effects and is not so slow that it is wasted. When the array of irradiation devices (85) is activated, they are powered by a control system and power supply (95) associated with each irradiation station. The cans should be centered under the irradiation optics (91) while being rotated by the turntable.The optics (91), array (85), and power and control system (95) rotate with the turntable (84) and maintain their relative positions throughout the rotation process. Encoders (93) continuously feed rotational position and velocity information back to a central control system (99) via cables (98). The central control system (99) feeds back relevant information needed by each irradiation station (91) to provide the local control (95) necessary to properly operate each station at the appropriate timing and power levels. Each control system (95) monitors the cooling status of each station and feeds back this information to the central control (99) via interconnections (98) for complete supervisory control of all stations.

[0083] As the cured cans (89) approach the unloading station, they slowly come into contact with the stripper arm (90) and are gradually and slowly pushed out of the station onto the already moving vacuum conveyor belt (88). The cured cans (89) continue down the vacuum conveyor (88) and pass under an inspection station (97) on their way out of the curing system. An alternative to a vacuum conveyor is a trackwork system, which uses gravity or large volumes of low-pressure air to move them out of the curing system.

[0084] Another viable configuration of the embodiments described herein is somewhat similar in that it employs continuous rotary or linear motion, but uses a fixed-position illumination system that strobes to energize the can as it passes the correct position. This configuration requires very powerful, very short pulses of illumination energy, which must be precisely timed. The duration of such a fast strobe pulse will depend on the exact implementation details and throughput speed of the material handling system, but pulses of less than 500 milliseconds will be required. In some high-speed applications, this could be as short as 300 microseconds. Using an overpulsed array of narrowband infrared semiconductors, very high output power can be achieved in a very short time. The concept here is that if the normal electrical supply current rating of the array is x, then high peak power can be achieved by roughly 10x, 15x, or even 20x for a very short time. For example, if 1700 joules are required for proper exposure, a group of illumination arrays that would normally be able to output 1700 joules at 15 amps of current input for 1.7 seconds can be strobed to produce 1700 joules at 10 times the normal current, i.e., 150 amps, for 170 milliseconds. This overall configuration requires fewer mechanisms and eliminates the need to mechanically move or dynamically articulate the illumination arrays. However, more electrical and electronic work must be done to pulse such a large current, and the arrays must withstand the impulse power and produce a proportionately higher output. They must be tested to verify that they can actually be overpulsed to this extent and maintain a usable service life for a particular implementation.

[0085] The strobe and overpulse configuration can be implemented in either a rotary motion system or a continuous linear motion system. Either arrangement allows cans to pass single-file under the strobed narrowband illumination array for curing exposure. Practitioners of the embodiments described herein continually debate the relative merits of material handling throughput speed versus illumination system power and configuration. A more powerful illumination system irradiates for a shorter period of time, ostensibly in direct proportion to the power it incorporates. For example, for practical purposes, a 2000-watt array irradiates approximately twice as fast as a 1000-watt array, but to achieve a particular throughput rate, the 1000-watt array requires additional material handling equipment operating at a slower speed, since the system must be designed with more serial or parallel mechanisms. A material handling system, whether a starwheel, conveyor, or other system, operating at twice the speed can process twice as many cans in a given period of time. However, curing at twice the speed requires approximately twice the power output, such as narrowband illumination arrays and larger power supplies. Higher-power illumination systems generally require significantly more cooling, and everything in the system, including the optical train, must be able to handle the much higher power levels. Similarly, high-speed material handling equipment presents unique 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 of 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 to divide the system into to achieve a specified throughput. They must then determine the amount of power required by the illumination system to cure at the speed required by the material handling system.

[0086] A typical can line currently splits its production flow into seven lanes for the coating of the inside of cans. One of these lanes can be scheduled for maintenance at any time while the other six are running continuous production. The full output of these six active lanes (coated cans) is combined and returned to bulk transport before passing through the IBO. In contrast, according to the embodiment described herein, each curing lane can cure individual cans at a production rate of, for example, 300 cans per minute (which equates to 1,800 cans per minute for six lanes). In the embodiment described herein, while split, each lane would proceed through its corresponding curing lane. Therefore, because the curing lanes are parallel and independent, they can be started and stopped independently. They maintain their independence for control, service, and speed optimization. This configuration of independent curing lanes allows any lane to be started or stopped for any reason without shutting down production of the entire plant or line. This allows for scheduled maintenance while production continues, and allows for spontaneous maintenance or line blockages to be cleared without stopping production. If electronic troubleshooting or component replacement is required, this can be done seamlessly while normal production continues. Separate curing lanes can then be merged into one high-speed, single-file lane to feed the next manufacturing step (typically the necker / flanger).

[0087] Another arrangement that can be implemented in accordance with the embodiments described herein incorporates high-speed, indexed rotary motion. This includes turntable or starwheel arrangements incorporating a rotary indexing configuration that repeatedly moves through a specified arc of motion. The indexing technique is one of many mechanical or electromechanical considerations. Periodic indexing is one of many technologies, including electric servo, cam, ratchet or clutch mechanical, pneumatic, or other indexing mechanisms. While employed in a unique manner here, all of these mechanical mechanisms are well documented in the literature and patent databases and will not be described in detail here. Commercially available products require highly specialized and appropriate tooling to process cans through a high-speed irradiation curing station, although the basic mechanism may be sufficient to meet this need.

[0088] A properly indexed star wheel or turntable can move the cans under the irradiation source and provide a place for the cans to dwell while the irradiation source is turned on, indexing the cans from under the narrowband irradiation source, bringing new cans into position, irradiating them, and finally turning off. This repetitive indexing cycle has the advantage of providing any length of dwell duration required for the application. Speed ​​and throughput require matching a specific irradiance power with the correct speed of the indexer to meet the overall production demands of the system while still providing the required number of joules of energy for proper curing.

[0089] The indexing arrangement can allow a single can to be moved in and out of the narrowband irradiation source, or each index can be used to move multiple cans into position under multiple irradiation sources. Thus, the system can be designed to be optimized by having the perfect number of irradiation sources to handle the curing job, while still allowing the indexing turntable to run at a speed within the reliable range of the mechanism.

[0090] It is important to design a servo-driven indexing system to properly set the ratio between indexing dwell time, indexing time, and indexing arc length. This allows for narrowband irradiation source configurations that maximize irradiation time while minimizing actual indexing time. It is also possible to have multiple stations for irradiation, thereby eliminating the need for all irradiation at a single station. This technique could facilitate staged irradiation, allowing the paint in the can to be heated through a series of irradiations and stops. Because aluminum can cool very quickly, this can generate a significant amount of waste heat, necessitating the injection of more heat at subsequent stations. However, this may be a viable configuration if the paint needs to be held at a higher temperature for a longer period of time to accommodate a particular type of paint. It could also allow for multiple repeated irradiations when a longer irradiation period is required than would otherwise be possible. This, when carefully configured, could potentially achieve higher throughput rates. In some cases, a longer effective duration may be required to drive off water or for other curing reasons.

[0091] Any implementation of the rotary motion configurations of the embodiments described herein can utilize gravity to assist the movement of cans through their various respective trackwork. As cans move through the trackwork on their way to or from the narrowband, high-speed radiant curing station, they typically come into contact with one another. A steeply inclined or vertical trackwork filled with cans is very useful for providing gentle pressure to push the next can into its respective turntable transport nest. For example, in FIG. 5, the trackwork (81) can be configured to be either vertical or at a steep angle, so that cans (82) push against one another, whether supported by the vacuum conveyor (80) or not. This gentle force of gravity can be increased or decreased by increasing the verticality or stack length in front of the transport nest (86). Then, with the help of the peel-off guide (87), the next can is gently guided into the transport nest (86).

[0092] Another way to implement the embodiments described herein is through a linear escapement configuration, such as that shown in FIG. 4. This configuration has two parallel conveyors, an input conveyor and an output conveyor, arranged parallel to each other with space between them for the escapement tracks and stations. A programmable escapement pusher is positioned along the input conveyor and configured to push cans onto the escapement track between the two conveyors at the appropriate time. A narrowband irradiation system is installed above each escapement track workstation, allowing cans to be irradiated for the time required for proper curing as they are pushed out and dwell at the workstation. Once the curing time is complete, the can is pushed out of the workstation at the appropriate time onto the output conveyor, where it fits into the gap between other cans already being processed on the high-speed exit conveyor. This type of arrangement allows for highly programmable, long-dwell times, and highly parallel processing. It is usually low-cost to implement and offers more flexibility and modularity than most other configurations, but it requires more sensing, more programming, and more articulation. The linear escapement configuration of Figure 4 is described in detail here.

[0093] The linear escapement configuration functions as follows. Referring to Figure 4, the incoming conveyor (111) delivers a single-file, upright row of cans. The open tops face away from the vacuum conveyor through which they are transported. The conveyor's (111) input speed depends on the throughput and handling speeds required to maintain the overall balance of the system. The actual speed and belt position are constantly monitored by an encoder (109) directly linked to the drives of the conveyors (118) and (119). The encoder is connected to a computer, control system, or programmable controller that constantly records the belt position and, via input from a photocell (100), monitors the position of every can entering the material handling system. As an uncured can (112) enters the incoming belt, the control system determines which irradiation station is available for the can to enter. Seven completely independent irradiation curing stations (106) are shown in Figure 4. If the programmable controller determines that a can should be sent to Station 3, the Station 3 Diverter (114) extends its fingers with very precise timing, positioning itself to provide the necessary vector force to direct the can toward irradiation Station 3. As a can approaches Station 3 and contacts the diverter's (114) fingers, a pushing, sliding motion is created by a combination of dynamic forces provided by the moving belt. As the can is pushed onto the Station 3 side track conveyor, 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 uncured cans to each curing station (106) until the center points of the uncured cans below the curing station (106) are aligned with the center point (110). The diverter (105) continues to move cans to the curing stations (106) until a photocell (120) confirms their arrival. At the moment of arrival, the diverter conveyor (105) stops the conveyor movement and the illumination station (106) is activated, illuminating the interior of the can. The electro-optical system can be very similar to that shown in Figure 2.When the time the narrow band curing system has been switched on indicates that the correct number of energy joules has been applied to the can's interior, the narrow band curing system (106) is switched off and the control system knows the cured can is ready for removal. The control system, which tracks the position of all cans in the system, knows how long it will take the diverter conveyor to transport the can to the exit conveyor (108). When the timing is correct but a gap (107) between cans occurs, as shown in Figure 4, it reactivates the diverter conveyor, ready to transport the cured cans so that there is the proper gap between them as they move down the exit conveyor (108). It knows the speed of the diverter conveyor (105) and can adjust those speeds, if equipped, to encourage reasonably even can spacing on the exit conveyor (108). The diverter conveyor (105) can be equipped with a perforated belt that can be vacuumed to securely hold the cans and allow them to be rapidly accelerated. The exit conveyor (108) can also be equipped with vacuum holes (104) that can be vacuumed to firmly press the cans down onto the belt for better acceleration and control. The entrance conveyor (111) is driven by a motor (119) and gear drive (118), while the exit conveyor (108) is similarly driven by a motor (101) and gear drive (102), both of which are variable speed motors that can be adjusted by the control system to achieve the smoothest meshing depending on the supported production rate. The diverter (114) must be designed so that its fingers are fast enough to deflect cans, but smoothly enough to avoid tipping or deforming the cans. However, the fingers must also retract quickly enough to get out of the way before the next can arrives. The control system must know the response times for extending and retracting the fingers and must be able to coordinate the timing of all cans being transported, diverted, and removed from the system on conveyor (108).

[0094] Many of the functions of the embodiments described herein, such as generating narrowband infrared energy (or broadband energy), forming the cans, inspecting the cans / coatings and / or feedback information, and performing can handling, are controlled in at least some form by a suitable controller or control system. Such a controller or control system can take a variety of forms depending on the particular implementation, but in at least one form is implemented with appropriate hardware configurations and / or software routines to achieve the form and functionality of the embodiments described herein. Furthermore, such a controller or control system may be, for example, a standalone system, a distributed system, or incorporated into another or more comprehensive system.

[0095] The different types of factors that can be used to implement the embodiments described herein, as detailed above, are primarily to facilitate the direct narrowband irradiation portion of the curing process. Depending on various factors, the above configuration may need to be enhanced to achieve complete curing. One form of enhancement may include having a preheating section through which the can passes immediately before the narrowband irradiation section. This facilitates preheating of the can and reduces the joules of energy required by the narrowband irradiation section.

[0096] Another form of augmentation can include a post-blow section after narrowband irradiation. Because wet paint is mostly liquid water, the water must be driven off at some point during the curing process. Once the water evaporates just before the curing and crosslinking temperature is reached, the water vapor must be removed from the can. This may require warm air or blowing air onto the can to remove the water vapor from the can. This can be configured as a post-heat section, either as a circular or linear arrangement with trackwork directing the cans through each section.

[0097] The preheat section can be hot air or radiant, and can be equipped with, for example, banks of quartz lamps to provide gentle radiant preheat. The augmentation section can vary widely depending on the exact situation, plant configuration, and local climate in which the system is installed. Those skilled in the art will understand that not only can narrow band curing systems be configured in many different ways beyond the specific examples taught herein, but that pre- and post-augmentation can also take many forms.

[0098] One important difference between the embodiments described herein and traditional methods for curing the interior of beverage cans is that the embodiments described herein use direct radiant energy for curing. Traditional IBO curing ovens heat the interior of the cans via hot air convection. IBOs heat the air through some form of natural gas combustion or electrical resistance heating. Both of these methods heat the air, which then heats the cans. Because the belt on which the cans rest is hot, a small amount of heat is also generated by conduction from the conveyor belt to the bottom of the metal can. These are both drawbacks and inefficiencies of IBOs. As the belt passes through the oven repeatedly, it is continually heated, drawing heat from the oven. Indeed, the current trend in vintage IBOs is that the majority of can heating occurs via direct, high-temperature convection.

[0099] Convection heating is generally an inefficient heat transfer process. It is a multi-step process, and losses inherently occur between each step. The air must first be heated, then contact the can, transferring its heat to the can and the paint. The same amount of hot air that hits the inside of the can also hits the outside of the can. Of course, the hot air hitting the inside of the can would first hit the paint and then heat the metal by thermal conduction. The hot air hitting the outside of the can would heat the metal, which would then heat the paint. In a perfect world, it would be far more desirable to heat only the paint to its crosslinking curing temperature. However, this is virtually impossible. Because the paint is in intimate contact with the aluminum substrate that makes up the can body and is so thin, heat is transferred directly to the metal substrate. This heating method heats the metal substrate as much as the paint. Furthermore, the hot air in an oven is not perfectly uniform. Hot spots inherently exist within the oven, and air movement varies, tending to overheat some cans and underheat others. The solution to this problem is to use more oven heat than is actually optimal to prevent under-cured cans.

[0100] In the case of aluminum cans in particular, holding the aluminum at these temperatures for any significant period of time will result in the aluminum weakening. It is well known in the industry that production cans must be manufactured heavier and stronger than final specification to withstand the weakening effects that occur when exposed to the high temperatures experienced in the IBO for 2-3 minutes.

[0101] It is not entirely clear whether this weakening effect is a tempering or annealing effect. Metallurgists disagree on what to name the effect. What is very clear and well-known is that aluminum is definitely weakened by passing through the IBO oven. It is generally believed that 8 to 10 percent of bottom inversion strength is lost as a direct result of passing through the oven.

[0102] Conventional annealing typically takes longer at higher temperatures than the cans spend in an IBO oven. A literature search confirms this for 3004 alloy and other similar alloy families. Digging deeper into the literature, at least one study indicates that this annealing and tempering process can occur very quickly within the can because aluminum is so thin. Aluminum is an excellent heat conductor, and with wall thicknesses of 3-4 thousandths of an inch, heat absorption is typically nearly instantaneous. This can be measured in seconds, not minutes or hours, as is the case with most items that are candidates for annealing.

[0103] 3004 alloy aluminum, also known as UNS A93004, has the following chemical composition in addition to the base aluminum: silicon 0.3% max, iron 0.7% max, copper 0.25% max, manganese 1%–1.5%, magnesium 0.8–1.3%, zinc 0.25% max, and other elements 0.05% or less each, totaling 0.15% or less. This alloy is available in several temper variations. Standard tempers available include 0 (annealed), H32, H34, H36, and H38. H indicates strain hardened, while H3X, which is strain hardened and stabilized, is available. A specific temper commonly used for aluminum beverage cans is H19, which is less strain hardened than H32 but harder than the annealed condition. The H19 temper appears ideal for handling the significant cold work that occurs during the D&I (Drawn & Ironed) process. Specifications for tensile strength vary from 26 KPSI to 41 KPSI. Yield strength varies from 10 KPSI for 0 temper or annealed products to 36 KPSI for the H38 temper.

[0104] An 8-10% reduction in can strength actually means a reduction in the buckle strength or bottom inversion strength the can can maintain under pressure. Note that buckle strength does not directly correlate with yield strength or tensile strength, as the exact can geometry and can thickness are critical factors in can strength. However, since these are consistent with what could be measured both before and after curing, it is clearly the changes in tensile strength and yield strength that are responsible for the loss of buckle strength or bottom inversion strength. Clearly, this annealing / tempering effect is a factor that must be addressed accordingly in the can manufacturing industry.

[0105] The embodiments described herein virtually eliminate this annealing / tempering effect that occurs with IBO. The embodiments described herein do not use IBO, but instead use a high-speed, narrow-band infrared radiation curing technique. The cans are lined up in a row, and radiation is directed at each can individually. They are cured sequentially, one at a time, rather than all at once as a group. The controllability and relative efficiency of narrow-band radiation heating allows the coating to reach full curing and crosslinking temperatures in just a few seconds. The can itself is not exposed to high temperatures during this short time, so there is no time for weakening effects to occur. Details and techniques for implementing this high-speed radiation curing technique are described in more detail throughout this application.

[0106] Based on the results of the absorption spectrum analysis, the penetration depth of the sprayed paint sample can be calculated. In this application, a shallow penetration depth is practically advantageous since it corresponds to a faster absorption of IR radiation.

[0107] The formula for penetration depth (95% absorption) is: β=(3 × l) / A where β is the depth in millimeters, l is the optical path length of the experimental sample, and A is the absorbance at a particular wavelength. As an example, for a wavelength of 1930 nm, the absorption is 1.526, resulting in a penetration depth of β = 3.93 mm. This means that infrared light must pass through a 3.93 mm thick paint film for 95% of the incident energy to be absorbed. This is clearly impossible, considering the thin 0.00254 mm paint film on the can sidewall. Fortunately, aluminum is an excellent reflector of IR radiation. The infrared radiation is slightly absorbed on its first pass through the sprayed paint, but then reflects off the aluminum substrate below the paint, passes back through the paint, and is absorbed again, thus beginning the process of reflection inside the can. With each reflected pass, it interacts with the sprayed paint and the aluminum wall. Not all of the energy is reflected; a small amount is absorbed by the aluminum, contributing heat energy to the aluminum surface holding the spray compound, further heating the compound and aiding in the curing process. It should be understood that if the aluminum gets hot enough, it may also cure the exterior decoration of the can, which may be desirable in some implementations as the system can be designed, configured or adjusted to accommodate such heating and curing purposes.

[0108] For the thinnest standard paint film thickness, the distance traveled through the sprayed paint film in a single reflection is 0.00508 mm, with two passes through the paint film. It must pass through the body of the can 774 times before interacting with the 3.93 mm sprayed paint film, which reaches the 95% absorption value determined above. For a 65 mm wide can (assuming perfectly perpendicular wall-to-wall reflections, which is not realistic), the light must travel approximately 50 m before being completely absorbed. This may seem like a long process, but the speed of light (c = 3 × 10 8m / s) is so fast that it is actually a very short process. Timing calculations for both the thinnest and thickest paint film thicknesses yield 0.17 nanoseconds for a 0.1 mil thickness and 0.03 nanoseconds for a 0.5 mil thickness. As this result shows, the time it takes for the energy to be emitted from the laser diode is actually much longer than it takes for it to be absorbed by the paint.

[0109] As mentioned above, the current traditional method for coating and curing cans utilizes a large oven equipped with a mass conveyor. Three successive sections heat the cans. The oven is supplied with natural gas so that the temperature in the final section is maintained between 375 and 450 degrees Fahrenheit. The cans are passed through this hottest section of the oven using the mass conveyor belt for a curing time of approximately one minute. Due to the high initial costs associated with oven heating procedures, these ovens are left on as long as possible, resulting in waste both during line down time or during line jams that can back up in front of or within the oven.

[0110] Table 1 shows the cost increase based on reasonable assumptions and current natural gas costs in the U.S. As shown in Table 1, maintaining a consistently high temperature inside the oven requires a significant amount of continuous heat. The cost of natural gas is also a significant factor in the total annual operating costs.

[0111] [Table 1]

[0112] The thick paint film results above were used to represent a worst-case scenario. Other differences between this analysis and the traditional variables include the difference in natural gas-to-heat conversion efficiency versus electricity-to-radiant heat conversion efficiency, the difference in $ / MCF of natural gas versus $ / kWh of electricity, and the difference in oven uptime versus diode array uptime.

[0113] While not directly comparable, the differences favor narrow-band radiant electric heating. If we assume that the uptime of the same line (the time actually used to produce cans) is 89% of all available time in a year, we assume that the ovens actually remain active for a longer period due to the cost and time associated with cold starts. So, while the line is producing cans 89% of the time, the ovens are actually kept at temperature 95% of the time. Narrow-band radiant heating elements, on the other hand, are designed to be pulsed, so they only use power when cans are present and actually curing. This not only improves efficiency during operation, but also allows the diodes to be shut down when the line is down for maintenance or due to a line blockage. The result is a diode array uptime equivalent to the actual line uptime.

[0114] From a purely environmental perspective, in our pro forma example, the 3,000,000 BTU / hr required to cure the cans and keep the oven in the correct temperature range can be converted to joules: 3,000,000 BTU = 3165,167,700 joules. Comparing this to the plug power per hour of a radiant heating system offers dramatic savings potential if the heat is properly "targeted," as shown in Table 2. The theoretical energy required by a narrowband radiant heating system to cure paint is over 12 times the energy required to heat a conventional oven. In other words, with current IBO technology, approximately 92% of the energy consumed is actually wasted.

[0115] [Table 2]

[0116] Comparing the results of current standard conventional curing methods with the embodiments described herein reveals significant savings of approximately $240,000 per year based on current cost estimates.

[0117] The benefits of this technology to can manufacturers are many. As explained in the pro forma example above, not only are there dramatic energy savings, but air pollution is also significantly reduced. The energy and cost savings are actually greater than in the example above. This is because it does not consider the energy savings from eliminating the need for a typical 95 HP electric motor and the high maintenance requirements of mass conveyor-style ovens. Perhaps the most dramatic benefit to can manufacturers is the fact that, if properly implemented, the embodiments described herein completely or nearly completely eliminate the annealing / tempering effect. As a result, can manufacturers can produce cans using less aluminum. While some production cans weigh approximately 0.34-0.39 ounces, it is understood that can weight / volume can vary as a function of, for example, the exact shape and material thickness. Also, can manufacturers periodically redesign cans and modify can-making tooling and manufacturing processes to change weight / volume (e.g., to lighten can weight). Furthermore, some cans, e.g., specialty cans, may be designed to have increased weight / volume. With clever implementation, it's possible to save 9 to 14 percent of the aluminum used. However, any reduction in the amount of aluminum, such as reducing the weight of the aluminum by 3%, 5%, 8%, or more, is beneficial. Since approximately 70% of the cost of a beverage can is the cost of the aluminum material, this represents a significant savings for the can manufacturer or can consumer. It also has other environmental benefits, as less aluminum needs to be mined, refined, manufactured, and transported.

[0118] Eliminating the weakening effect of the oven can have one or a combination of three benefits: The can could be made with current aluminum and tooling, but would be significantly stronger than current cans because the weakening of the aluminum would be eliminated. Alternatively, less aluminum would be required to manufacture the can. A third possibility is that cheaper, less alloyed, or lower tempered aluminum could be used instead of the current more expensive aluminum. A combination of these is also possible, depending on the manufacturer's choice of how to implement the embodiments of this technology described herein.

[0119] When employing the embodiments described herein, there are several novel ways to reduce the amount of aluminum used to manufacture cans. Manufacturers and suppliers of aluminum coil stock routinely charge a premium for rolling aluminum to a specific precision and thickness. While aluminum is sold by the pound, there are significant processing fees for rolling and finishing to a specific thickness. Although less aluminum weight is required, aluminum coil stock manufacturers must roll the aluminum thinner and to precise specifications. To maintain their profit position, they may charge a rolling premium that is greater than the cost of using thicker, heavier aluminum. If this is the case, savings may not be realized if a rolling mill adopts this business approach. A more novel way to implement the embodiments described herein would be to reduce the diameter of the cut edge of the blank and, therefore, the diameter of the resulting cup. The starting cup for a typical 12-ounce, two-piece can is 5.100 inches in diameter. This technique reduces weight by proportionally reducing the cup size, while maintaining the same coil sheet thickness and, therefore, the same rolling premium. The first step in the D&I process is deep drawing a "starting cup." Again, this falls under industry-standard pricing because the aluminum coil narrows but remains the same thickness; it simply needs to be narrowed. By starting with a smaller diameter starting cup, the final can body will settle into the thinner desired thickness specification in the finished can. There is no need to pay a premium for rolling the aluminum material to a thinner gauge specification. Tooling modifications or reconfigurations are understood by experienced tooling makers. To ultimately create the deep-drawn cup, a proportionally smaller diameter cup, which is the first step in the D&I process, tooling must be created or modified so that all parts of the tooling are correctly specified for the new diameter.Cups are made in a double-action cupping press, and tooling is available in many cup widths, depending on the design and vintage of the cupping press setup. The blank diameter must be reduced to reduce the so-called "cut edge." These blanks are tightly nested across the entire width of the coil at a 60-degree angle to the coil edge, minimizing the amount of scrap between blanks and leaving a minimal aluminum web between the tangential edges of the blanks. To implement this, the overall width of the coil stock is reduced and, across that width, the same number of cup blanks are produced as the number of larger-diameter, conventional-size blanks that could be produced before the width reduction. Another method is to maintain the original coil width but change the tooling so that more cup blanks and cups are produced across that width. In either case, the compound deep-draw tooling at each tooling station of the stamping die must be remade with the correct new diameter, clearance, and depth. New punches, drawing rings, hold-owns, and all associated tooling components must match the new diameter. The geometric relationships of each tooling station must be adjusted to maintain a tightly nested configuration and minimize scrap relationships between each blank. The tooling components are smaller in diameter, requiring less tool steel and machining, making them relatively less expensive than the current larger versions. While copper press tooling will need to be modified to produce the smaller diameter cups, the payoff for making that change is significant. The copper press, feeding equipment, and overall system balance can be reconfigured to use new or adjusted tooling.

[0120] To properly implement this technology, it is important to understand the details of how the embodiments described herein work. The embodiments described herein teach that the preferred practice is to inject intense infrared narrowband energy as directly as possible into the interior of the can and into the paint itself. This means projecting the infrared energy directly into the interior of each individual can, rather than wasting energy bouncing around in the factory or attempting to heat a group or cluster of cans. While it is possible to implement the embodiments described herein by irradiating the outside of the can, or both the outside and the inside of the can, a more efficient implementation is to direct the energy directly into the inside of the can. This is much more efficient because the photons from the narrowband energy actually penetrate the liquid, uncured paint and are partially absorbed. Some energy actually passes completely through the paint, being absorbed directly, and then reflects off the aluminum substrate and passes through the paint for this second pass and corresponding further absorption. The remaining energy is absorbed as the photons pass through the paint on their return journey, making two passes through the paint with each subsequent reflection. Because the paint film is so thin, it cannot quickly absorb all of the photonic energy, and the photon continues its reflective path until it hits the next coated surface. Imagine a billiard ball bouncing off the inside surface of a can, passing through the paint on an inbound and outbound pass. Continuing the billiard ball analogy, the reason the billiard ball eventually slows down and stops is because it loses all of its energy on the bumpers, reducing rolling friction. Similarly, photons lose energy in two primary ways: energy is absorbed as it passes through the paint on each pass, and a small amount of energy is lost in the aluminum on imperfectly reflected impacts. Depending on the wavelength of narrowband infrared radiation utilized, anywhere from several hundred to approximately 1,500 reflections can occur before the entire amount of photonic energy is absorbed and the paint film and aluminum are heated.Of course, the thicker the paint film, the more energy is absorbed by the paint per pass. A longer path through the paint means more absorption occurs due to photon impacts that occur while the photon is passing through the paint. As an example, a steeper angle of entry and passage through the paint provides a longer path length and therefore more absorption.

[0121] There are several ways to generate intense, narrowband irradiance energy and effectively direct it toward the inside of the can. While broadband irradiance energy is possible, it is much more difficult to implement effectively and efficiently. For example, broadband energy generated by quartz lamps cannot be switched on and off at the kind of speed required for truly clean implementation. Quartz lamps take seconds to rotate and fully warm up when switched on, and in many configurations, the optimal heating time may be only one or two seconds, or even a fraction of a second. Also, due to their inherent shape and filament configuration, it is much more difficult to focus the energy precisely where it is needed. This does not allow for precise delivery of the correct number of joules to a small area, but tends to work more effectively when joules of energy are delivered in a flood arrangement to a larger, more specific area that is difficult to control. Broadband sources, due to their inherent characteristics, do not facilitate ultra-rapid curing. Therefore, they can rapidly overheat the can, potentially inducing some or all of the annealing effect. Both narrowband illumination and semiconductor-based generation of narrowband energy have many advantages. First, they can be switched on and off at microsecond speeds. They generate photonic energy only when receiving a practical DC voltage input (typically 1.2 to 3.3 volts) and do not have the hysteresis or high blackbody equivalence that would cause substantial output after the electrical input current ceases to flow. This is something that cannot be achieved with quartz or gas discharge lamps. Broadband sources typically operate at very high temperatures, creating a series of implementation challenges. Their presence reduces component reliability due to the extremely high temperatures of the entire curing environment, necessitating the need for optics capable of handling much higher temperatures. They inherently have a much shorter lifespan and require frequent replacement, increasing maintenance and downtime. Furthermore, narrowband setups also facilitate superior implementation of anti-reflection coatings, since they can be designed and optimized precisely for the narrow wavelength band employed. They do not need to be broadband anti-reflection coatings, which are difficult to optimize. Similarly, optical components and coatings such as cold mirror coatings can be more easily designed because they only need to be tailored to a narrow, specific wavelength range. Because lenses focus different wavelengths at different distances, greater precision can be advantageous when designing optical trains for narrowband systems. While it is important to understand that narrowband can be interpreted differently, it refers to the generation of optical or photonic energy with a full width at half maximum typically less than 100 nanometers. If the narrowband energy source is a solid-state or semiconductor source, this is usually the case unless broadband fluorescence is added to the device configuration. While the raw output from an LED is generally inherently narrow within its range, the output of a laser diode is narrower, e.g., less than 20 nanometers (nm), typically less than ±10 nm (full width at half maximum), or even as narrow as ±1 nm (full width at half maximum) for certain types. For example, VCELS and SE-DFB devices typically have bandwidths less than ±2 nm (full width at half maximum). The exact bandwidth is less important than the central wavelength of the output. The wavelength can determine how quickly the energy is absorbed by the coating itself. The transmittance of the coating can be measured at various wavelengths, allowing you to select the wavelength that achieves the best absorption results.For example, in at least some embodiments, the narrowband infrared energy used for curing (which, as detailed above, can be as narrow as ±1 nm (full width at half maximum) depending on the implementation) is matched to at least one absorption characteristic of the paint. Thus, for the example of a water-based epoxy paint typically applied to the interior surface of a can, the narrowband wavelength may be, for example, about 972 nm, falling in the 800-1200 nm range. As discussed herein, 972 nm represents a deep penetration wavelength for water-based epoxy paints. Substantially faster absorption by the paint is possible in the 1400-1600 nm range, e.g., about 1454 nm or 1456 nm, but the wall plug efficiency (wall plug efficiency) is not as high. Therefore, this tradeoff is a decision that system designers must make. Similar wall plug efficiency challenges exist in the 1850-2000 nm range, e.g., 1935 nm.

[0122] As with many high-power industrial processes, safety implementation is paramount in the mind of the system designer. Regardless of whether the embodiments described herein are implemented in the final design, appropriate safeguards must be in place to prevent physical or optical exposure to technical hazards. Powerful infrared energy can cause eye damage or blindness and must be prevented by safety design. The actual material handling portion of the system has many moving parts that present potential hazards due to movement or sudden activation to perform functions. Some form of physical or electronic detection guarding must be implemented to safely stop movement in the presence of humans. For all aspects of system safety, OSHA, CSA, or CE safety standards must be adhered to when designing the system.

[0123] The narrowband irradiation aspect of the system requires very strict attention to the system's safety. The intense infrared energy that is so effective at rapidly curing paint is extremely dangerous to the naked eye. It is invisible and powerful enough to quickly blind people and animals before they can blink. Even sunglasses or welding glasses are not sufficient to prevent the intense photonic energy from damaging the eyes, as they may have weak filters or filter out the wrong wavelengths. Some of the longer infrared wavelengths available for implementation do not penetrate the retina of the eye, but they can still damage the cornea, sclera, iris, and / or lens. Such wavelengths are often mistakenly referred to as "eye-safe," but this only applies with respect to potential damage to the retina. The system must be designed to prevent anyone from exposing their eyes to the narrowband photonic energy generated by laser diodes or arrays of such diodes beyond a minimum safe threshold. Failsafes, such as dual-backup interlock systems, can be designed into the control panel or safety guards. These should preferably be designed so that the guards cannot be removed while the narrowband device is powered. They should also preferably be designed so that the power source cannot be jumpered or jerry-rigged to power the device while the safety guards are removed. Furthermore, all enclosures and guards should preferably be designed to be light-tight when the narrowband device is capable of being powered. It is also strongly recommended that arrays be designed so that they cannot be casually connected to a power source when not in a system. This prevents service personnel or the curious from powering on the device and injuring themselves. Because powerful narrowband infrared energy is completely invisible to the human eye, the eye cannot activate the blink reflex until damage has occurred. While exposure to other parts of the body can be uncomfortable or even cause severe burns, it is less severe than momentary exposure to this energy to the eyes. Therefore, it is recommended that you adhere to all applicable agency safety standards and use sound design common sense to ensure that your narrowband high-speed curing system is safe.While it provides excellent usability, safety must be an integral part of all aspects of using a system constructed in accordance with the embodiments described herein.

[0124] Additionally, a powerful way to further improve the performance of the embodiments described herein involves incorporating special additives into the paint, which dramatically increase absorption at specific wavelengths. When carefully selected and matched to the wavelengths used for curing, this can deliver more heat to the paint and less to the aluminum or steel can. In other words, the additive or dew point makes the paint more absorptive at the wavelengths used, so more heat is applied directly to the paint itself rather than being conducted through the metal. This reduces bounce, thereby improving the efficiency of the system by reducing the energy wasted in non-curing functionality to achieve the required curing or crosslinking temperature.

[0125] The use of narrowband infrared energy in this curing system can also be incorporated to further optimize the coating used. Coating manufacturers can use IR-activated chemical reaction actuators (initiators) or accelerators (accelerators) suited to the purpose of in-can coating. Functional dyes capable of absorbing specific narrowband infrared wavelength bands are also available. Such dyes are manufactured, for example, by Yamada Chemical Industry. Narrowband IR irradiation can be used by chemical coating manufacturers in creative ways to improve coatings, reduce or eliminate BPA-based coatings, or improve performance in various ways. Some of the reflection within the can may inherently radiate energy from the open top of the can. A properly designed system employs appropriately positioned reflective surfaces to at least partially return the energy back into the can, where it is used for further curing until it is consumed. However, even the most reflective surfaces impart a few percent of the impact energy to the reflective material. These are often called Fresnel reflections. Also, some of the energy may be accidentally scattered or reflected and not return to the can. A properly designed reflective shape or cone (64) can provide better placement of the returning energy, encouraging more energy absorption with additional passes through the paint and reflections from the base material.

[0126] The concepts taught herein regarding how to implement the embodiments described herein for narrowband infrared radiation curing are intended to assist those wishing to configure the embodiments described herein for their specific application and production needs. Implementations may exist that go far beyond the specific examples given and differ in many respects from the embodiments described herein. Individuals or teams skilled in their respective technologies can accordingly extend the new concepts to meet their own application requirements.

Claims

1. Spray the paint onto the inside of the can. continuously transporting the cans to at least one curing station; the method comprises individually and electrically heating the cans using narrow band radiant infrared energy elements and optical elements made of semiconductors disposed in at least one curing station and on the exterior of each can so that the paint on the inside surface of each can of a series of consecutive production cans arranged in a row vertically reaches a temperature capable of achieving a crosslinking curing process of the paint and falls below that temperature in less than 20 seconds and within a time capable of preventing tempering or annealing from occurring in the can; A method for use in the interior coating and curing process in can manufacturing.

2. 10. The method of claim 1, wherein each can is formed by a reconfigured manufacturing tooling to reduce the diameter of the cut edge of the blank from which the can starting cup is drawn, such that the thickness of the coil stock aluminum is substantially the same as before the reconfiguration of the manufacturing tooling, but the width of the coil stock is narrowed to reduce the weight of aluminum required to produce each can by 3% or more.

3. Can designs and tooling are being modified to produce cans from thinner coil stock material to reduce the weight of aluminum used to manufacture the cans.

10. The method of claim 1, wherein the cans are subjected to reduced strength loss due to heating to achieve a crosslinking curing process of less than 20 seconds, resulting in cans having equivalent sidewall axial strength, bottom inversion strength, and overall strength compared to thicker cans subjected to longer curing times that weaken the aluminum.

4. 10. The method of claim 1, wherein the semiconductor-based system that generates the narrowband radiant energy can be switched on or off within microseconds and the can can be heated to a temperature that allows the paint to achieve a crosslinking curing process of the paint and below that temperature in less than 10 seconds.

5. 10. The method of claim 1, wherein the conveyor transports the cans during the curing process and utilizes continuous rotational motion, whereby at least one irradiation curing station rotates continuously in synchronization with the cans being cured, and at least one of electrical power, coolant, and control signals is associated with the at least one curing station via a rotary union.

6. 10. The method of claim 1, wherein at least one of the DC power supply, refrigeration heat exchanger, refrigeration chiller, refrigeration recirculation pump, and control system serving at least one curing station constitutes a continuous rotational motion curing system that moves in a rotational motion synchronous with the can, the continuous motion of the system serving the cooling function.

7. a conveyor transporting the cans during the curing process and utilizing a rotational motion for indexing, whereby a plurality of irradiation curing stations are located around, but not on, the turret, and a group of cans is loaded successively into a selected number of empty stations around the turret; 10. The method of claim 1, wherein the turret is rotationally indexed while cans are under respective narrow-band curing stations, the curing stations are operated to cure the cans, and then the turret is rotationally indexed again to remove the cured cans, while a new set of cans is indexed into position under the curing stations for curing, and the process is repeated.

8. 10. The method of claim 1, wherein each can is individually cured in less than 5 seconds.

9. 10. The method of claim 1, wherein the narrowband semiconductor device emits narrowband radiant infrared energy at a wavelength that matches the absorption characteristics of a paint applied to the interior surface of each successive can.

10. 2. The method of claim 1, wherein the wavelength of the narrowband radiant infrared energy used for heating is in any one of the following wavelength ranges: 800 nm to 1200 nm, 1400 nm to 1600 nm, and 1850 nm to 2000 nm.

11. 10. The method of claim 1, wherein the narrowband radiant infrared energy used for heating is generated using at least one of a semiconductor-based illumination device, a light emitting diode (LED), and a laser diode.

12. 10. The method of claim 1, wherein the illumination-producing semiconductor device comprises a multi-device array in which the combined optical output power of more than 10 individual semiconductor devices produces a total optical output power of more than 100 watts.

13. 10. The method of claim 1, wherein the semiconductor device is a laser diode having a full width at half maximum output power of less than 20 nanometers.

14. 10. The method of claim 1, wherein the semiconductor device is a surface-emitting laser diode having a full width at half maximum output power of less than 2 nanometers.

15. 10. The method of claim 1, wherein the energy source comprises an array of surface emitting laser diodes that produce an output of photonic energy between 825 and 1075 nanometers.

16. 10. The method of claim 1, wherein the cans are handled so as to allow individual curing of a lane of cans at a production rate of over 300 cans per minute.

17. 10. The method of claim 1, wherein the multiple parallel curing stations are arranged to operate all but one lane to individually cure at a total throughput rate of over 1800 cans per minute, the one lane that is not in operation being available for maintenance that may be required or for additional production as needed, thereby achieving a higher level of up-time overall.

18. 10. The method of claim 1, wherein greater than 3% aluminum is saved in the can manufacturing process as a result of rapid curing in less than 20 seconds, without the use of hydrocarbon-based fuels, and eliminating annealing and weakening of the aluminum that makes up the can.

19. 10. The method of claim 1, wherein specific additives are added to the coating to interact with the wavelengths of narrowband infrared light used to improve performance or provide new functionality to the cured coating.

20. 10. The method of claim 1, wherein the paint is reformulated to eliminate BPA or other undesirable components from the current paint formulation.

21. 10. The method of claim 1, wherein the equipment of the method is configured to be easily started and stopped without adverse effects on the can or on downstream portions of the manufacturing process.

22. 10. The method of claim 1, wherein the method implements the ability to respond instantaneously to modulation of the method during operation as a result of sensory information obtained from the inspection system.

23. 1. A system for use in an interior coating and curing process in can manufacturing, comprising: The paint is sprayed onto the inside of the can, a can handling system configured to continuously move production cans through at least one curing zone; and an array of semiconductor-based narrowband irradiation devices arranged to individually electrically heat the interior surface of each can; Each can is moved to a curing zone using an optical element located outside the open end of the can to bring the coating applied to the interior surface of each successive production can in a series of successive production cans to a temperature capable of achieving a crosslinking curing process for the coating in less than 20 seconds and below that temperature within a time sufficient to prevent tempering or annealing from occurring in the can. system.

24. 24. The system of claim 23, wherein the array of semiconductor-based narrowband illumination devices and optical elements are positioned just outside the top plane of the cut edge of the can and direct more than 90% of the narrowband infrared photonic energy generated by the array of semiconductor-based narrowband illumination devices to cure inside the can, concentrating most of its energy in the upper half of the sidewall and exposing the lower part of the can by internal reflection.

25. The optical element is at least one microlens array aligned with each device of the array of semiconductor-based narrowband illumination devices for forming a column of energy; a focusing lens configured to focus the column of energy toward and through a pinhole or aperture into the interior of the can to be cured; and said pinhole or aperture providing an opening through the vertex of a surface having a reflective designed shape; 25. A system as claimed in claim 23 or 24, wherein the surface having a reflective engineered shape functions to return narrow band energy escaping from the can back into the can.

26. 26. The system of any one of claims 23 to 25, wherein the surface having the reflective engineered shape is provided with ventilation slots or openings to facilitate the removal of vapors from the curing can.

27. 27. The system of any one of claims 23 to 26, wherein the surface having the reflective engineered shape is generally conical and made from any one of copper, aluminum, gold-plated metal, silver-plated material, and nanostructures.

28. 28. The system of any one of claims 23 to 27, wherein the optical element and the array of semiconductor-based narrowband illumination devices are mounted in a housing configured to prevent diverted infrared energy from escaping the housing except through a pinhole or aperture, and comprising a recirculating water cooling system to maintain the array and optical element at an acceptable operating temperature in a production curing environment.

29. 29. The system of any one of claims 23 to 28, wherein the array of semiconductor-based narrowband irradiation devices includes at least one array of laser diodes disposed on the outside of the cans, and a corresponding optical element is articulated inside each can during at least a portion of the curing operation.

30. the optical element includes an objective lens configured to receive energy from the array of semiconductor-based narrowband illumination devices via an optical system and mirror assembly, the system further comprising an insertion and extraction mechanism for translating the optical element into the can via a reflective containment plate; a reflective containment plate configured to be positioned over each can such that optical transmission of energy is aligned when a portion of the optical assembly is positioned inside the can by the insertion mechanism, allowing irradiation to be activated when the optical train is properly positioned inside the can where curing is to occur; A system according to any one of claims 23 to 29.

31. an input trackwork or conveyor configured to move the individual containers sequentially and systematically or smoothly in single file toward the second conveyor; a second conveyor configured as a rotating turret for transferring individual containers to and from at least one curing station; photonic energy from at least one of the array of surface emitting laser diodes passes through a columnar optic and is then focused by at least one focusing lens element onto a pinhole or aperture beyond which the photonic energy diverges to illuminate the inside of the sidewall of the coated container; at least one curing station including an optical configuration in which such pinhole or aperture is located at the apex of a reflection cone, such reflection cone functioning to reflect photonic energy back into the container for further curing; The coating cures in less than 20 seconds and within a time sufficient to prevent weakening or annealing of the aluminum comprising the container; the second conveyor delivers the containers and directs them to a third conveyor configured to remove the containers discharged from the second conveyor; The empty pockets are used to load waiting uncured cans to continue the curing sequence, and the cured containers are transferred on a third conveyor to subsequent container manufacturing operations. A system for use in manufacturing a container, which cures paint sprayed onto the interior wall of said container.

32. the subsequent container manufacturing operation includes an inspection station located on the third conveyor; the inspection station at least images and locates bare metal areas within each container and verifies coating and curing accuracy to the extent that the cured coating is not of sufficient quality level based on the images; 32. The system of claim 31, wherein a third reject station after the inspection station rejects containers having defective coatings and then sends a signal to at least one of the coating system control system and the curing control system to modify the respective processes.

33. an input trackwork or conveyor configured to move the individual containers in single file toward the second conveyor; a second conveyor configured to use a rotating table for moving each individual container into and out of the curing station at least once; and at least one curing station incorporating one of a reflector designed to redirect photonic energy from the array through an opening in the top of the container directly onto the paint sprayed on the interior surface of the container to aid in the curing process; The coating cures in less than 20 seconds and within a time sufficient to prevent weakening or annealing of the aluminum comprising the container; the second conveyor is configured to rotate and discharge cured containers onto the third conveyor while continuously loading new uncured cans into the vacant positions; a third conveyor configured to receive the cured containers and transport the cured containers to a subsequent container manufacturing operation; A system for use in the manufacture of cans or open-top containers for curing paint sprayed onto the interior walls of said containers.

34. 34. The system of claim 33, wherein the second conveyor is in a rotating configuration with multiple curing stations arranged around its periphery, each curing station operable simultaneously to cure the interior of the container with infrared energy generated by at least one laser diode array.

35. The system of any one of claims 33-34, wherein the plurality of curing stations comprises more than eight curing stations.

36. 36. The system of any one of claims 33 to 35, wherein the second conveyor is in a rotating configuration having multiple curing stations that rotate synchronously with the containers, allowing curing to continue without starting or stopping the table rotation, and wherein at least one of power, cooling, and control signals is associated with the curing stations via at least one rotary union.

37. 37. A system as claimed in any one of claims 33 to 36, wherein the input trackwork or conveyor is configured to use gravity to advance the containers in single file and to use gravity pressure to feed individual containers onto a second conveyor.

38. a can handling system configured to spray paint onto the interior surfaces of the production cans and to continuously move the production cans through at least one curing zone; a broadband infrared source arranged to individually electrically heat the interior surface of the can, and using optical elements arranged to direct light toward the upper sidewall of the interior surface of the can, to bring the paint on the interior surface of each successive production can in a series moving through the curing zone to a temperature sufficient to accomplish a crosslinking curing process for the paint and below that temperature in less than 20 seconds and within a time sufficient to prevent tempering or annealing from occurring in the can; and A control system configured to use sensor information to modulate the output of the broadband infrared source to maintain consistent curing temperatures and results.

1. A system for use in an interior coating and curing process in can manufacturing, comprising:

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