Automatic injector and method for processing mixed plastics

Abstract

The present invention relates to an injection moulding machine incorporating an extruder having a support mechanism for supporting an Archimedes screw in the extruder for transferring a plastic mass from an extruder tube to an injector tube coupled to the extruder tube. Inside the extruder tube, the function of which is to heat and melt thermoplastics mixed with ground thermosets and other waste, there is a threaded spindle for moving the mass to the injector tube. The injector tube has a high-pressure hydraulic system for transporting the mass by means of an internal threaded spindle, which sends the plastic mass to fill a mould by flooding and suction, with internal cooling. The aim is to enable the production of heavy, low-cost items. The invention enables the joint recycling of thermoplastics and thermosets, with or without the addition of additives, including controlled amounts of shredded tires, fabrics, polystyrene, Tetra Pak, WPC and EVA, inter alia.

Description

[0001] AUTOMATIC INJECTION MACHINE AND MIXED PLASTIC PROCESSING METHOD

[0002] Technological sector of the invention

[0003]

[0001] The present invention belongs to the sector of recycling of waste products, and relates, more specifically, to an injection molding machine for processing mixed plastics with an Archimedes screw support mechanism for transferring plastic mass to the injection tube with a high-pressure hydraulic system for filling the mold by flooding, suction and internal cooling. Prior art

[0004]

[0002] With the exponential growth in the use of plastic by industry for the production of the most diverse products for domestic, commercial and industrial use, due to its low cost compared to other materials, plastic waste has become a problem with an enormous environmental impact that, directly or indirectly, affects the ecological balance of forests, rivers and seas, with serious consequences for human beings.

[0005]

[0003] According to the American journal Science Advances, in its July 19, 2017, issue, humans generated 8.3 billion tons of plastic between 1950 and 2015. That's practically one ton per inhabitant of planet Earth in 65 years, with more than half of that generated between 2004 and 2017. Also according to the published research, less than 10% of this amount has been recycled, and the situation could worsen. Researchers predict that over the next 30 years, another 12 billion tons of plastic waste will end up in landfills or the environment.

[0006]

[0004] Recycling has long been the solution, through a chain that involves direct processes of collection, separation, processing, and industrial reuse. But not all types of plastic are recycled. Recyclable plastics are called thermoplastics. The current recycling process lacks the technology to profitably recycle plastics that don't melt, nor to process mixed plastics into usable, durable products capable of reducing and reversing the impacts caused by the presence of

[0007] REPLACEMENT SHEET (RULE 26) plastic in the environment. This occurs for well-known reasons: the processing of recycled plastic by extruders, with its limitations to certain types of products of lower complexity and strength due to low compression; the processing of plastic for granulation, which uses only one type at a time; and the technology of conventional injection molding machines, which processes only one type of plastic at a time, after a long and expensive process of selection, pressing, purification, and extrusion to manufacture the granules, which restricts the recycling process and contributes to the increase in waste.

[0008]

[0005] Currently, the costs of materials such as wood, metal, iron and cement are high, which is why efforts have been made to produce composite materials to replace them.

[0009]

[0006] These composite thermoplastic materials are produced by processing plastic materials to which various chemical additives are added to improve the mechanical and chemical properties of the thermoplastic materials. However, thermoplastics manufactured in this way are compromised by high costs and sometimes result in non-recyclable products, as is the case with WPC, which mixes plastic with sawdust. Furthermore, the production process of extruded plastic products facilitates the propagation of microplastics, due to the lack of compression during manufacturing.

[0010]

[0007] Current plastic waste recycling processes consist primarily of the following steps: Extrusion: preceded by separation, selection, fragmentation, washing, agglutination, and melting, enabling the production of granules and straight products without compression; and Injection: preceded by granulation, new melting, injection, cooling, and demolding. Various additives may be added to these processes, which may generate non-recyclable products because they cannot be returned to the purification process required for use in conventional technology.

[0011]

[0008] For example, patent document BR 102021008011-6 describes a transmolding machine designed for processing mixed recycled plastics (MKS), using a traction and transmission system for feeding and injection.

[0012] REPLACEMENT SHEET (RULE 26) of the plastic mass through a single point of attack, in the so-called flood injection process. Although it represents an improvement over traditional methods, this solution still has significant technical limitations, such as the use of conventional heating in the extruder tube, which can generate temperature spikes that are detrimental to the homogeneity of the mixture, and the lack of internal cooling in the mold, which impacts the thermal efficiency and scalability of the process. Furthermore, the system described operates with molds without direct integration with the machine, which hinders full automation and requires longer cycle times for cooling and demolding.

[0013]

[0009] The proposed automatic injection molding machine overcomes these limitations through significant innovations. The extruder tube is now heated using a plasma system, which ensures more precise and uniform thermal control, avoiding critical temperature variations that could compromise the melting and proper mixing of recycled materials. The mold, in turn, is directly coupled to the machine and features an internal cooling system, allowing for greater thermal efficiency, reduced cycle time, and increased production scale. Furthermore, the flood filling system is maintained, with a single point of attack, but incorporates an additional suction system in the mold, which facilitates and speeds up cavity filling, eliminating air pockets or molding defects. These improvements enable full process automation and consolidate a more robust, efficient technical solution suited to the reality of large-scale mixed plastics recycling.

[0014]

[0010] In this sense, it is understood that in state-of-the-art plastic processing machines, in which conventional systems such as extrusion and injection are used, the operating principle consists of pushing, under pressure, the molten material to proceed with the filling by expansion, through the extruder nozzle or holes in the molds in the case of an injection mold. In the extrusion system there are one or more introduction zones, which may be a funnel or a side feed screw; a worm, also called an Archimedes screw, and a

[0015] REPLACEMENT SHEET (RULE 26) cylindrical body called shell, inside which the worm screw moves and can withstand high pressures and temperatures of up to 500°C.

[0016]

[0011] Consequently, in state-of-the-art plastic processing machines that operate systems such as extrusion and injection, when the molten plastic mass reaches the compression zone, it cannot be compressed if there is a large amount of minerals present, since these are not compressible. This causes the screw to jam or break in extruders due to the very high resistance torque forces. In the case of injection molding machines, the same situation causes clogging of the mold filling channels. For this reason, the use of minerals in thermoplastic mixtures must be restricted in conventional technologies, or the mixture will not achieve the desired mechanical strength. In the case of injection molding, the presence of any mixture that destabilizes the melt makes filling by expansion unfeasible, due to the ease with which non-compressible elements clog the channeling ducts of the mass expansion process for filling the mold.

[0017]

[0012] It is also worth noting that in the plastic processing machines currently used, in extrusion and injection systems, the heated plastic mass for generating products is subjected to pressure from the machines themselves in a continuous system, in the case of extruders, or an expansion molding system, in the case of injection molding machines, which makes them complex and expensive as there is greater dependence on the control of variables.

[0018] Novelties of the Invention

[0019]

[0013] To use recyclable plastic in conventional injection molding machines, it is necessary to select the different types of plastic, wash, grind, dry, bind, and extrude for granulation. This purification process is necessary to avoid clogging the mold ducts when filling by expansion carried out by the injection molding machines.

[0020]

[0014] This process does not allow the recycling of various types of plastics such as thermosets, due to the high cost and difficulties inherent in the purification process. Obviously, due to the characteristics of the current state of the art, the mixture

[0021] SUBSTITUTION SHEET (RULE 26) of thermosets and thermoplastics is impractical, making it more viable to acquire pure plastic granules from the chemical industries, without mixtures and ready for use in conventional injection molding machines.

[0022]

[0015] Thus, current recycling, determined by the current state of the art, results in a process that recycles only thermoplastics that meet the cost-benefit, such as PET, PP, PAD or LDPE, resulting in considerable volumes of waste discarded in landfills and dumps. At this technological limit, recycling assumes the role of a highly beneficial activity, but with insufficient results.

[0023]

[0016] As an example in the prior art, the traction / torque process of conventional extruders is cited through the use of reduction gearboxes, which are expensive to acquire and maintain. Furthermore, to obtain the necessary force in the reduction gearbox, high-driving motors are used, causing an increase in costs and in the production process due, also, to the high consumption of electrical energy.

[0024]

[0017] In this context, the automatic injection machine is a system coupled to the extruder part, which operates without the need for a reduction box, as it obtains the necessary force through a low driving force motor coupled to the worm screw, reducing the cost of the machine, maintenance, parts and energy consumption, increasing the cost-benefit of the entire process.

[0025]

[0018] Therefore, in the current state of the art of conventional injection molding machines, it is essential that the plastic is specific and granulated, allowing uniformity of melting, to avoid clogging of the flow channels when filling the molds by the expansion process, given that this is done by a sequence of points interconnected by passage channels. Otherwise, the part will be damaged if one of the points or channels becomes clogged.

[0026]

[0019] Furthermore, in order to increase the weight of the products generated in the molds, in the current state of the art, it is essential to increase the force under pressure and the mold's barring capacity, generating a proportional increase: in the cost of the machine, in the electric motors in power (HP), in the complexity of the molds, in the consumption of electrical energy and in the cost-benefit in general.

[0027] REPLACEMENT SHEET (RULE 26)

[0020] An injection molding machine in the current state of the art requires a 15 HP motor to generate a 500g product. The increase in the weight of the product implies increasing the capacity of the motor and the pressure system, which leads to a considerable increase in the price of the machines.

[0028]

[0021] The automatic injection machine allows the mold to be filled by flooding and suction, as it works by reducing the mold bus pressure, enabling the increase of the injection tube and the injection nozzle, through the special coupling of the internal jacket of the injection tube to a piston driven by a 10 HP motor, enabling the production of heavy objects through the flooding and suction process at a single point and internal cooling of the mold, which makes it radically different from the current system which is expansion.

[0029]

[0022] The automatic injection molding machine enables the production of heavier products, reducing costs, and enabling the processing of ground mixed plastics. This means recycling all types of plastic with or without a mixture of other components, such as additives, fabrics, tires, rubber in general, Styrofoam, sawdust, Tetra Pak, WPC, among others. The new technology also works with pure granulated plastics obtained from the petrochemical industry, increasing their usefulness.

[0030]

[0023] Also, the performance of the automatic injection machine is superior, since at the end of the molding process the heated plastic mass is received when it enters the injection tube, eliminating the need for heating for melting at this stage, which facilitates the process.

[0031]

[0024] The current state of the art injection uses the heated thermoplastic mass expansion system to fill the mold at several points. The automatic injection machine, on the other hand, allows the mold to be filled by flooding and suction at a single point and internal cooling, producing superior results on a production scale and reducing the costs of the conventional mold, which is subject to duct clogging.

[0032] REPLACEMENT SHEET (RULE 26) Description of the attached drawing

[0033]

[0025] In order for the present invention to be fully understood and put into practice by any technician in this technological sector, it will be described in a clear, concise and sufficient manner, based on the attached drawing, which illustrates and supports it, listed below:

[0034] Figure 1 represents a schematic view of the equipment.

[0035] Detailed Description of the Invention

[0036]

[0026] The automatic injection machine allows the use of thermoplastics, ground thermosets and other waste, such as polystyrene, tires, fabrics, foams, etc., in proportions determined according to the type of product desired.

[0037]

[0027] The support mechanism (1) for the Archimedes screw consists of a device comprising a motor with a gear on a large pulley with a spinning top coupled to the shaft fixed to the larger pulley for moving the Archimedes screw.

[0038]

[0028] The Archimedes screw consists of a mechanical tube made of ST52 steel, with an inner diameter of 100 mm and an outer diameter of 120 mm, and a length of 2000 mm, where there is no honing process. The thread is made of 1045 steel. In the manufacturing process, a 5 / 8” (15.875 mm) square steel bar is used, where the thickness of the bar is reduced to 12 mm, through the milling process. Subsequently, a disc is welded with this bar, with the face coinciding with the beginning of the tube, and then spiral welding is carried out, with a pitch of 120 mm, with the revolutions ending at the end of the opposite face of the tube. Finally, the part is ground on a mechanical lathe, where the outer diameter is reduced to 149.5 mm, where it must be inserted into the extrusion tube (3) with interference.

[0039]

[0029] The extrusion tube (3) receives the Archimedes screw, and works with heating by plasma or electrical resistances (4), where the melting of ground thermoplastics mixed with ground thermosets inserted through the funnel (2) occurs, and is intended to deliver the mass to the injection tube (7) with injector barrel and injector nozzle.

[0040] REPLACEMENT SHEET (RULE 26)

[0030] The extrusion tube (3) is composed of a mechanical tube made of ST52 steel, with an inner diameter of 150 mm, an outer diameter of 180 mm and a length of 2010 mm, where it is obtained by the rolling process, and undergoes a mechanical process of honing the inner face of the tube. The tube has a slot tangent to the outer face of the tube, which passes through the inner wall of the tube, with a width of 100 mm and a length of 150 mm, at a distance from the flat face of the tube of 90 mm.

[0041]

[0031] The injection tube (7) is driven by a directional hydraulic control system with high pressure hoses (6) powered by a motor that moves an internal threaded spindle that drives the heated mass to fill the mold by flooding and suction at a single point.

[0042]

[0032] The injector tube (7) is composed of a mechanical tube made of ST52 steel, with an internal diameter of 160 mm, and an external diameter of 190 mm, with a length of 1560 mm, which is obtained by the rolling process, and undergoes a mechanical process of honing the internal face of the tube. The tube (7) has a perpendicular cutout of the same tube, 140 mm long, and a cross-section with a radius of 190 mm, forming a fit with the external face of the main tube, with the cutout positioned at a tangent distance of 65 mm from the flat face of the tube. The tube has a hole with a diameter of 160 mm concentric to the internal diameter of the cutout, forming a “Tee” shaped through piece.

[0043]

[0033] The Archimedes screw is inserted into the extrusion tube (3) with minimal clearance between the inner face of the cylinder and the outer face of the screw. The recycled material is poured into the hopper (2) located in a tangent slot of the extrusion tube (3), the Archimedes screw must rotate at an angular speed of approximately 60 rpm, transporting the material along the extrusion tube (3), where it must be heated and plasticized at a temperature of 200°C, using plasma heating or nine mica resistors (4) of 2000 to 2400W.

[0044]

[0034] The plasticized material is poured into the injection tube (7), where the material must fill the internal cavity of the tube (5), where it is kept heated, while

[0045] REPLACEMENT SHEET (RULE 26) is transferred through the extrusion tube (3). After filling the cavity (5), the material is pressurized and injected into a mold, using a hydraulic cylinder with a 1500mm stroke, exerting a force of 12 tons, at a pressure of 130bar.

[0046]

[0035] The mold (8), with specific characteristics for the machine, has a single filling point through the flooding, suction and internal cooling process. The automatic injection machine works with a single mold (8) in a single-point flooding and suction filling system. After filling, the mold is cooled and disassembled, releasing the product.

[0047]

[0036] In this sense, the mixed plastic processing method, reproduced by the automatic injection molding machine, comprises the following steps: a) Inclusion of mixed ground plastics (thermoplastics, thermosets and scraps) in the hopper (2) installed in the extruder tube (3); b) The support mechanism (1) for the Archimedes screw propels the plastic mass from inside the extruder tube (3) to the injection tube (7) at an angular speed of 60 rpm, transporting the material along the tube, where it is heated and plasticized at a temperature of 200°C, using plasma heating or nine mica resistors (4), with a power of 2000 to 2400W; c) The plasticized material is poured into the injection tube (7), where the material must fill the internal cavity of the tube (5), where it is kept heated;d) After filling the cavity (5), the material is pressurized to a pressure of 130 bar and injected into a mold (8), by a directional hydraulic control system with high-pressure hoses powered by a motor that moves an internal threaded spindle that propels the heated mass to fill the mold (8) by flooding and suction at a single point; e) After filling, the mold is cooled and disassembled, releasing the product.

[0037] It is important to emphasize that the descriptions provided are not intended to limit the forms of execution of the inventive concept proposed herein, but rather to illustrate and make understandable the conceptual innovations revealed in this solution.;

[0048] REPLACEMENT SHEET (RULE 26) Therefore, the descriptions and images must be interpreted in an illustrative and non-limiting manner, and there may be other equivalent or analogous forms of implementing the inventive concept revealed herein that do not stray from the spectrum of protection outlined in the proposed solution.

[0049] REPLACEMENT SHEET (RULE 26)

Claims

CLAIMS 1- AUTOMATIC INJECTION MOLDING MACHINE FOR MIXED PLASTIC PROCESSING, composed of a support mechanism (1) for the Archimedes screw, which consists of a device with a geared motor on a large pulley with a spinning top coupled to the shaft fixed to a larger pulley; the Archimedes screw is composed of a mechanical tube made of ST52 steel, with an internal diameter of 100 mm and an external diameter of 120 mm, with a length of 2000 mm, the thread is made of 1045 steel, with a pitch of 120 mm, with an external diameter of 149.5 mm, where it is inserted into an extrusion tube (3) with interference; the extrusion tube (3) is composed of a mechanical tube made of ST52 steel, with an internal diameter of 150 mm, an external diameter of 180 mm and a length of 2010 mm, and has a slit tangent to the external face of the tube, which passes through the internal wall of the same, with a width of 100 mm and a length of 150 mm, at a distance from the flat face of the tube of 90 mm, where the inlet funnel (2) is located;interconnected, there is an injection tube (7) composed of a mechanical tube of ST52 steel, with an internal diameter of 160 mm, and an external diameter of 190 mm, with a length of 1560 mm, having a perpendicular cutout, 140 mm long, and a cross-section with a radius of 190 mm, forming a fit with the external face of the main tube, with the cutout positioned at a tangent distance from the flat face of the tube, of 65 mm; it also has a hole of 160 mm in diameter concentric to the internal diameter of the cutout, forming a passed piece in a “Tee” shape; and the Archimedes screw rotates at an angular speed of approximately 60 rpm, transporting the material along the extrusion tube (3); and characterized by being composed of an extrusion tube provided with heating by plasma or electrical resistances (4) with a power of 2000 to 2400 W;of an injection tube (7) driven by a directional hydraulic control system with high pressure hoses (6) driven by a motor that moves an internal threaded spindle that drives the mass heated to 200°C and filled into the internal cavity of the tube (5), being pressurized and injected using a hydraulic cylinder with a 1500mm stroke; exerting a force of 12 tons, at a pressure of 130 bar to fill the mold (8) by flooding and suction at a single point. 2- MIXED PLASTIC PROCESSING METHOD, reproduced by the equipment described in claim 1, which has the following steps: a) Inclusion of mixed ground plastics (thermoplastics, thermosets and scraps) in the hopper (2) installed in the extruder tube (3); b) The support mechanism (1) for the Archimedes screw propels the plastic mass from inside the extruder tube (3) to the injection tube (7) at an angular speed of 60 rpm, transporting the material along the tube; c) The plasticized material is poured into the injection tube (7); d) The material is pressurized and injected into a mold (8); e) After filling, the mold (8) is disassembled, releasing the product; characterized in that in step a) the plastic mass inside the extruder tube (3) is heated and plasticized at a temperature of 200°C, using plasma heating or nine mica resistors (4), with a power of 2000 to 2400W;in step c) the plasticized material poured into the injection tube (7) is kept heated in the internal cavity of the tube (5); in step d), after filling the internal cavity (5), the plasticized material is pressurized to 130 bar by a directional hydraulic control system with high-pressure hoses driven by a motor that moves an internal threaded spindle that drives, through a hydraulic cylinder, the heated mass to fill the mold (8) by flooding and suction at a single point; and in step e), the mold (8) is cooled before being disassembled.;

Images