A wood plastic physical micro-foaming extrusion injection molding machine and molding process

Abstract

The invention relates to a wood plastic physical micro-foaming extrusion injection molding machine and a molding process, belonging to the field of wood plastic production equipment, comprising a twin-screw extruder and an injection machine, characterized in that the twin-screw extruder comprises a barrel, two screws are arranged in the barrel, a hopper is arranged at the input end of the barrel, a barrel precursor is arranged at the output end of the barrel, a connector is arranged below the barrel precursor, a supercritical fluid injector is arranged at the side end of the connector, a first cavity is arranged in the connector, the upper end of the connector is connected with the barrel precursor through the first cavity, the side end of the connector is connected with the supercritical fluid injector through the first cavity, a gear pump is arranged below the connector, the injection machine comprises an injection oil cylinder, an injection cylinder precursor, and a nozzle, and the gear pump is connected to the injection cylinder precursor through a check valve below; the invention aims to solve the problems of uneven pore size of wood plastic products and large brittleness, poor density, easy cracking and high density of product molding, and the overall equipment structure is simple and easy to process.

Description

Technical Field

[0001] The invention relates to the technical field of wood-plastic material production equipment, and in particular to a wood-plastic physical micro-foaming extrusion injection molding machine and a molding process under the trend of replacing wood with plastic and lightweighting materials. Background Art

[0002] Wood-plastic composite materials are a new type of composite materials obtained by adding plant fibers such as wood, sisal, bagasse, rice bran, bamboo powder, etc. as fillers in powdered or fibrous forms into thermoplastic plastics and then compounding them through melt processing. Compared with traditional wood materials, it has the advantages of being beautiful, water-resistant, insect-resistant, corrosion-resistant, and not easy to crack. It is widely used to make wood substitute products, such as various packaging materials, pallets, warehouse pads, or outdoor building materials, public facilities, etc. In addition, most wood-plastic composite materials are made from recycled resources, which is conducive to saving resources and protecting the environment. Most of the wood-plastic composite materials currently used on the market are cut or post-processed after extrusion molding.

[0003] Wood-plastic composite foam materials are traditionally prepared by chemical foaming: plastic, wood powder, mineral fillers, additives, modifiers and foaming agents are mixed according to mass ratio, and heated and melted by plastic molding equipment to form a composite material with continuous and evenly distributed foaming holes. The product density is close to that of wood, while the mechanical strength is much higher than that of wood. Since the amount of resin is reduced by half, the product cost is lower. Compared with general wood-plastic composite materials, wood-plastic foam materials have the advantages of light material and stronger wood feel, which meets the requirements of lightweight material development. In recent years, its development and application have attracted wide attention.

[0004] At present, the common foaming methods used for ordinary plastic products include physical foaming and chemical foaming. The chemical foaming method is to use chemical methods to generate gas to foam plastics. The chemical foaming agent added to the plastic is heated to decompose and release gas to foam. In addition, the gas released by the chemical reaction between the plastic components can also be used to foam. The process of using chemical foaming agents for foaming plastic injection molding is basically the same as the general injection molding process. The heating, mixing, plasticization and most of the foaming and expansion of the plastic are completed in the injection molding machine. The physical foaming agent used in the physical foaming method has a relatively low cost, no residue after foaming, and little effect on the performance of the foamed plastic. In the prior art, a Chinese invention patent application with application number 201610606340.8 discloses a carbon dioxide foaming plastic extrusion granulation and molding equipment, which is equipped with a supercritical carbon dioxide filling valve on the barrel of a twin-screw extruder, so that the melt and carbon dioxide are mixed in the barrel of the screw extruder for foaming plastic raw material particles.

[0005] The above-mentioned physical foaming is for the foaming of plastic raw material particles, that is, PE, PVC and other raw material particles are used as the foaming and plasticizing objects. First of all, it is not suitable for the production of injection molded wood-plastic products. Secondly, when used to process wood-plastic products with wood powder and plastic as the main raw materials, if the above-mentioned plasticizing equipment is used, then after the physical foaming agent is injected into the melt in the screw extruder, due to the presence of raw wood powder in the melt, the supercritical gas of the foaming agent will diffuse along the fibers of the wood-plastic, which will easily cause the release of gas, resulting in poor foaming effect of the wood-plastic product. In addition, the structural requirements of the carbon dioxide filling valve are very strict and it is not suitable for processing with standard parts. The filling valve was modified in this article before it can be adapted to the equipment, and the equipment processing is relatively complicated. Chemical foaming can solve the problem of excessive gas release. However, chemical foaming not only uses more foaming agents, but also produces larger bubbles. The uniformity is greatly affected by the uniform distribution of the foaming agent. The maximum foaming weight of the foamed product can reach 0.6-0.7g / cm³, and the weather resistance is greatly affected by the instability of the chemical agents. Most importantly, for the chemical foaming of wood plastic, a foaming regulator must be added to reduce the large bubbles in the melt to prevent excessive gas release.

[0006] In addition, due to the different fluidity of wood powder and plastic, the molecular structures cannot adhere to each other, and continuous extrusion molding is easier, but traditional injection molding cannot be achieved, or even if it is achieved, the product molding is brittle, poor in density, and easy to crack, and the purpose of replacing wood with plastic for lightweighting cannot be achieved. Therefore, for processing wood-plastic injection molded micro-foam products with wood powder and plastic as the main raw materials, special equipment is required. The present invention is to fill this gap and provide a production equipment and process specifically for wood-plastic physical micro-foam products. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a wood-plastic physical micro-foaming extrusion injection molding machine and a molding process in view of the deficiencies in the prior art, so as to solve the problems that gas is easily released during the physical foaming process of wood-plastic injection molding products, the pore size of the products is uneven, the products are brittle, poor in density, easy to crack, and have high density. The overall equipment structure is simple and easy to process.

[0008] The technical solution of the present invention to solve the above technical problems is as follows: a wood-plastic physical micro-foaming extrusion injection molding machine, comprising a twin-screw extruder and an injection mechanism, characterized in that the twin-screw extruder comprises a barrel, two screws are arranged in the barrel, the two screws are arranged in parallel and mesh with each other, a hopper is arranged at the input end of the barrel, a barrel precursor is arranged at the output end of the barrel, a connector is arranged below the barrel precursor, a supercritical fluid injector is arranged at the side end of the connector for conveying supercritical gas, a first cavity is arranged in the connector, the upper end of the connector is connected to the barrel precursor through the first cavity, the side end of the connector is connected to the supercritical fluid injector through the first cavity, a gear pump is arranged below the connector, the injection mechanism comprises an injection cylinder, an injection cylinder precursor, and a nozzle, the front end of the injection cylinder is connected to the injection cylinder precursor, the front end of the injection cylinder precursor is connected to the nozzle, and the gear pump is connected to the top of the injection cylinder precursor through a check valve below to prevent backflow impact during injection.

[0009] Furthermore, the wood-plastic physical micro-foaming extrusion injection molding machine comprises an upper and lower layer, wherein the upper layer is a twin-screw extruder, and the injection mechanism is arranged directly below the twin-screw extruder, and the upper twin-screw extruder and the injection mechanism are arranged in parallel.

[0010] Furthermore, the first cavity is configured to be hollow in the vertical direction, a diverter is provided in the first cavity, the diverter is arranged in the lower middle part of the first cavity, a preset distance is left between the top of the diverter and the upper wall of the first cavity, the connection port between the supercritical fluid injector and the first cavity is arranged above the diverter in the first cavity, and the lower end of the diverter protrudes outward from the connector and is inserted into the gear pump.

[0011] Furthermore, the diverter includes a cylindrical portion and a conical portion arranged at both ends of the cylindrical portion, and the surface of the cylindrical portion is provided with at least one annular groove along its circumference, and the surfaces of the cylindrical portion and the conical portion are also provided with a preset number of strip grooves, each of which is connected to the annular groove, and the strip grooves on the surface of the conical portion are all converged to the end of the conical portion. The annular groove divides the diverter into at least two parts, and the strip grooves on the surfaces of the diverters of adjacent parts are staggered in the vertical direction.

[0012] Furthermore, the gear pump includes a gear pump housing, in which two gear shafts are arranged, the two gear shafts are arranged in parallel in a horizontal shape and mesh with each other, the second gear shaft is arranged directly below the first gear shaft, the upper end of the gear pump housing is connected to the connecting body as an input end, and the lower end of the gear pump housing is connected to the injection cylinder front body as an output end. The material enters the gear pump housing and is sequentially sheared by the rotation of the first gear shaft and the second gear shaft and output to the injection cylinder front body.

[0013] Furthermore, the check valve includes a valve housing and a ball, the top end of the valve housing is set as the input end, the bottom end of the valve housing is set as the output end, and the ball matched with the output port is set in the valve housing.

[0014] And a molding process using the injection molding machine as described above, characterized in that it includes the following steps:

[0015] 1) The raw materials include a mixed powder consisting of polyethylene, wood powder, additives and supercritical gas;

[0016] 2) The mixed powder is heated and mixed evenly, and then cooled, and the mixed powder enters the barrel through the hopper, and is mixed, plasticized and extruded in a twin-screw extruder to obtain a melt;

[0017] 3) The melt enters the connector through the barrel precursor and is preliminarily mixed with the supercritical gas from the supercritical fluid injector in the first cavity;

[0018] 4) Under the action of the gear pump, the melt and the supercritical fluid are evenly mixed to obtain a stable melt polymer. After the rotation shearing of the internal gear pump, the molecular chain structure of the melt is broken up and fully mixed with the supercritical gas molecules. The melt polymer, wood powder and supercritical gas are coupled and wrapped to form a stable melt polymer;

[0019] 5) The molten polymer is injected into the mold cavity, and after low-pressure filling, the gas bubbles grow until the cavity is filled, completing the product molding.

[0020] Furthermore, the additives are composed of color powder, coupling agent, internal lubricant and external lubricant.

[0021] Furthermore, the weight ratio of the raw materials is:

[0022] Polyethylene 50-60

[0023] Wood powder 29-44

[0024] Color powder 1-2

[0025] Coupling agent 3-5

[0026] Internal lubricant 0.5-1

[0027] External lubricant 0.5-1

[0028] Supercritical Gas 1-2

[0029] Furthermore, the coupling agent is maleic anhydride, the internal lubricant is stearic acid, the external lubricant is PE wax, and the supercritical gas is nitrogen or carbon dioxide.

[0030] The beneficial effects of the present invention are as follows: the present invention provides a barrel precursor and a connector at the front end of a twin-screw extruder, the powdered material is extruded into a melt to the connector through the twin-screw extruder, and is mixed with a supercritical gas from a supercritical fluid injector in the connector, and then sheared by a gear pump to shear large bubbles into uniform small bubbles, without the need to add a foaming regulator, thereby preventing the release of gas, uniformly mixing the melt and the supercritical gas, and improving the uniformity of bubbles and the quality of the melt after plasticization; compared with the prior art, in which the melt and the supercritical gas are mixed in a twin-screw extruder, the present solution can solve the problem of supercritical gas being diffused and released along the fibers of the wood-plastic composite, effectively realize the full mixing and plasticization of wood powder and plastic particles in the twin-screw extruder, avoid the poor bonding force between the wood powder and the plastic particles, uneven foaming, and extremely easy release of bubbles caused by the mixing of supercritical gas when the two are mixed, thereby solving the problems of large brittleness, poor density, and easy cracking of the product molding; in addition, the present solution has a simple structure and is easy to install. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic diagram of a three-dimensional structure of an embodiment of the present invention;

[0032] Figure 2 It is a schematic diagram of the main structure of an embodiment of the present invention;

[0033] Figure 3 is a schematic diagram of a top view of the structure of an embodiment of the present invention;

[0034] Figure 4 yes Figure 2 A magnified view of the structure at center A;

[0035] Figure 5 Schematic diagram of the structure of a flow divider in one embodiment of the present invention.

[0036] In the figure: 1. twin-screw extruder, 11. barrel, 12. screw, 13. hopper, 14. reduction box, 15. drive motor, 2. barrel precursor, 3. connector, 31. first cavity, 4. supercritical fluid injector, 5. gear pump, 51. gear pump housing, 52. gear shaft, 521. first gear shaft, 522. second gear shaft, 53. universal coupling, 54. gear pump drive assembly, 6. injection mechanism, 61. injection cylinder, 62. injection cylinder precursor, 63. nozzle, 7. check valve, 71. valve housing, 72. sphere, 8. diverter, 81. cylindrical portion, 82. conical portion, 83. annular groove, 84. strip groove. DETAILED DESCRIPTION

[0037] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The embodiments given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0038] As shown in the figure, a wood plastic physical micro-foaming extrusion injection molding machine of this embodiment includes a twin-screw extruder 1 and an injection mechanism 6. The twin-screw extruder 1 includes a barrel 11, and two screws 12 are arranged in the barrel 11. The two screws 12 are arranged in parallel and mesh with each other. The two screws 12 are connected to a drive motor 15 through a reduction box 14 at the front end thereof. A hopper 13 is arranged at the input end of the barrel 11, and a barrel precursor 2 is arranged at the output end of the barrel 11. A connector 3 is arranged below the barrel precursor 2, and a supercritical fluid injector 4 is arranged at the side end of the connector 3. The supercritical fluid injector 4 is arranged outside The connecting body 3 is connected to a metering pump for quantitatively delivering supercritical gas. A first cavity 31 is provided in the connecting body 3. The upper end of the connecting body 3 is connected to the barrel precursor 2 through the first cavity 31. The side end of the connecting body 3 is connected to the supercritical fluid injector 4 through the first cavity 31. A gear pump 5 is provided below the connecting body 3. The injection mechanism 6 includes an injection cylinder 61, an injection cylinder precursor 62, and a nozzle 63. The front end of the injection cylinder 61 is connected to the injection cylinder precursor 62. The front end of the injection cylinder precursor 62 is connected to the nozzle 63. The gear pump 5 is connected to the top of the injection cylinder precursor 62 through a check valve 7. The wood-plastic physical micro-foaming extrusion injection molding machine of this embodiment includes two layers, the upper layer is a twin-screw extruder 1, and the injection mechanism 6 is arranged directly below the twin-screw extruder 1. The upper twin-screw extruder 1 and the injection mechanism 6 are arranged in parallel.

[0039] The molding process using the injection molding machine as described above includes the following steps:

[0040] 1) The raw materials include a mixed powder consisting of polyethylene, wood powder, additives and supercritical gas;

[0041] 2) The mixed powder is heated and mixed evenly, and then cooled, and the mixed powder enters the barrel through the hopper, and is mixed, plasticized and extruded in a twin-screw extruder to obtain a melt;

[0042] 3) The melt enters the connector through the barrel precursor and is preliminarily mixed with the supercritical gas from the supercritical fluid injector in the first cavity;

[0043] 4) Under the action of the gear pump, the melt and the supercritical fluid are evenly mixed to obtain a stable melt polymer;

[0044] 5) The molten polymer is injected into the mold cavity, and after low-pressure filling, the gas bubbles grow until the cavity is filled, completing the product molding.

[0045] The additives are composed of toner, coupling agent, internal lubricant and external lubricant;

[0046] The coupling agent is maleic anhydride, the internal lubricant is stearic acid, the external lubricant is PE wax, and the supercritical gas is nitrogen.

[0047] The weight ratio of each raw material in this embodiment is as follows:

[0048] Polyethylene 50

[0049] Wood powder 44

[0050] Toner 1

[0051] Maleic anhydride 3

[0052] Stearic acid 0.5

[0053] PE wax 0.5

[0054] Liquid nitrogen1

[0055] In this scheme, a barrel precursor and a connector are arranged at the front end of a twin-screw extruder. The powder and granular materials are extruded into a melt to the connector through the twin-screw extruder and mixed with the supercritical gas from a supercritical fluid injector in the connector. The large bubbles are then sheared into uniform small bubbles through the rotation shearing of a gear pump. No foaming regulator is required to be added, thereby preventing the release of gas and uniformly mixing the melt and the supercritical gas, thereby improving the uniformity of bubbles and the quality of the plasticized material. A mold cavity is arranged at the front end of the injection mechanism, and the fully mixed melt-supercritical gas mixture is pushed into the mold cavity of the next level through an injection cylinder to complete molding and cooling. The process of using the above equipment is to first complete the mixing of wood powder and plastic particles, and then blend them with supercritical gas, and adopt a two-step extrusion injection molding method. The upper stage adopts a parallel twin-screw structure for efficient mixing and plasticization, and mixes and plasticizes the wood powder and plastic particles to solve the problems of uneven mixing and easy deposition of powder in a single screw; a common storage cylinder is set at the lower stage to store the mixed melt; an internal meshing gear pump mixing device is set between the twin screws and the injection cylinder of the upper stage, in order to fully mix the supercritical gas in the melt with the melt. Compared with the prior art that completes the mixing operation of the melt and the supercritical gas in the twin-screw extruder, the present solution can effectively achieve the full mixing and plasticization of the wood powder and the plastic particles in the twin-screw extruder, avoiding the poor bonding force and uneven foaming of the wood powder and the plastic particles caused by the mixing of the supercritical gas when the two are mixed, thereby solving the problems of large brittleness, poor density, easy cracking and high density of the product molding; in addition, the structure of the present solution only requires the basic twin-screw extruder structure, and there is no need to add or modify the valve parts of the twin-screw extruder. The structure of each component is simple and easy to install.

[0056] In another embodiment of the present invention, the first cavity 31 is configured to be hollow in the vertical direction, and a diverter 8 is provided in the first cavity 31. The diverter 8 is arranged in the middle and lower part of the first cavity 31, and a preset distance is left between the top of the diverter 8 and the upper wall of the first cavity 31, that is, a space for blending the supercritical gas and the melt extruded by the twin-screw extruder is formed here, and the connecting port between the supercritical fluid injector 4 and the first cavity 31 is arranged above the diverter 8 in the first cavity 31, and the lower end of the diverter 8 protrudes outward from the connector 3 and is inserted into the gear pump 5.

[0057] By using a connector with the above-mentioned first cavity structure built in, the supercritical gas can be smoothly blended with the melt from the twin-screw extruder. With the provided diverter, the liquid supercritical gas and the melt can be initially mixed, which not only makes the mixing more uniform but also has little impact on the equipment, thereby extending the service life of the equipment.

[0058] The weight ratio of each raw material in this embodiment is as follows:

[0059] Polyethylene 55

[0060] Wood powder 35

[0061] Toner 2

[0062] Maleic anhydride 4

[0063] Stearic acid 1

[0064] PE wax 1

[0065] Liquid Carbon Dioxide 2

[0066] In another embodiment of the present invention, the flow divider 8 includes a cylindrical portion 81 and conical portions 82 disposed at both ends of the cylindrical portion 81. Figure 5 As shown, at least one annular groove 83 is provided on the surface of the cylindrical portion 81 along its circumference, and a preset number of strip grooves 84 are also provided on the surfaces of the cylindrical portion 81 and the conical portion 82, each strip groove 84 is connected to the annular groove 83, and the strip grooves 84 on the surface of the conical portion 82 are all gathered at the end of the conical portion 82, and the annular groove 83 divides the diverter 8 into at least two parts, and the strip grooves 84 on the surfaces of the diverter 8 of adjacent parts are staggered in the vertical direction.

[0067] The structure of the above-mentioned diverter can achieve full mixing of the supercritical gas in the melt through the cooperation of the annular groove and the strip groove, so that the gas is more evenly distributed in the melt.

[0068] The weight ratio of each raw material in this embodiment is as follows:

[0069] Polyethylene 60

[0070] Wood powder 29

[0071] Toner 2

[0072] Maleic anhydride 5

[0073] Stearic acid 1

[0074] PE wax 1

[0075] Liquid Carbon Dioxide 2

[0076] In another embodiment of the present invention, the gear pump 5 includes a gear pump housing 51, and two gear shafts 52 are arranged in the gear pump housing 51. The two gear shafts 52 are arranged in parallel to be horizontal and mesh with each other. The second gear shaft 522 is arranged directly below the first gear shaft 521. The upper end of the gear pump housing 51 is connected to the connector 3 as an input end, such as Figure 4 As shown, the gear pump housing 51 is provided with a vertical second cavity, the upper end of which is connected to the diverter, and a gear shaft is arranged below the diverter in the gear pump housing 51. The arrangement direction of the two gear shafts is along the vertical direction, that is, the same as the entry direction of the melt. The first gear shaft 521 is connected to the gear pump drive assembly 54 through a universal coupling 53 as a driving wheel, and is specifically driven by an asynchronous motor through a frequency converter, a reduction box and a transmission mechanism, and the speed is adjustable. The second gear shaft 522 is used as a passive wheel, which is driven by the first gear shaft 521 to mesh and rotate with it. The two cooperate to convert large bubbles in the melt from the upper end into small bubbles, which are more difficult to release, and are conducive to uniform mixing of the gas in the melt. The lower end of the gear pump housing 51 is connected to the injection cylinder precursor 62 as an output end, and the mixed melt enters the injection cylinder precursor.

[0077] The structural design of the gear pump enables the melt to be mixed more fully under the rotational shearing action of the gear shaft.

[0078] In another embodiment of the present invention, the check valve 7 includes a valve housing 71 and a ball 72, the top end of the valve housing 71 is set as the input end, the bottom end of the valve housing 71 is set as the output end, and the valve housing 71 is provided with a ball 72 adapted to the output port; it can effectively prevent backflow impact during injection.

[0079] The supercritical gas is sent into the syringe through an external metering pump, and the syringe is injected into the first cavity 31. The supercritical gas, polymer melt, and wood powder polymer are preliminarily mixed through a shuttle valve to form a supercritical fluid wood-plastic melt polymer. After the rotation shearing of the internal gear pump, the melt molecular chain structure is broken up to be fully mixed with the supercritical gas molecules. The large bubbles become small bubbles under the action of rotation shear, which is more difficult to release. The supercritical gas of the melt polymer, wood powder, and small bubbles is coupled and wrapped to form a stable melt polymer; the polymer is injected into the mold cavity, and after low-pressure filling, the gas bubble pores grow until the cavity is filled, and the product is formed. The gas injection port, that is, the supercritical fluid injector, is located at the front end of the diverter, and a one-way valve device is provided at the rear end of the internal gear pump to prevent backflow impact during injection.

[0080] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0081] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0082] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0083] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0084] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine the different embodiments or examples and the features of the different embodiments or examples described in this specification without contradiction.

[0085] Combine and combination.

[0086] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A wood plastic physical micro-foaming extrusion injection molding machine, comprising a twin-screw extruder (1) and an injection mechanism (6), characterized in that: The twin-screw extruder (1) comprises a barrel (11), two screws (12) are arranged in the barrel (11), the two screws (12) are arranged in parallel and mesh with each other, a hopper (13) is arranged at the input end of the barrel (11), a barrel front body (2) is arranged at the output end of the barrel (11), a connector (3) is arranged below the barrel front body (2), a supercritical fluid injector (4) is arranged at the side end of the connector (3), a first cavity (31) is arranged in the connector (3), and the upper end of the connector (3) is connected to the supercritical fluid via the first cavity (31). The barrel front body (2) is connected, the side end of the connecting body (3) is connected to the supercritical fluid injector (4) through the first cavity (31), a gear pump (5) is arranged below the connecting body (3), the injection mechanism (6) comprises an injection cylinder (61), an injection cylinder front body (62), and a nozzle (63), the front end of the injection cylinder (61) is connected to the injection cylinder front body (62), the front end of the injection cylinder front body (62) is connected to the nozzle (63), and the bottom of the gear pump (5) is connected to the top of the injection cylinder front body (62) through a check valve (7); The first cavity (31) is arranged to be hollow in a vertical direction. A flow divider (8) is arranged in the first cavity (31). The flow divider (8) is arranged in the middle and lower part of the first cavity (31). A preset distance is left between the top of the flow divider (8) and the upper wall of the first cavity (31). The connection port between the supercritical fluid injector (4) and the first cavity (31) is arranged above the flow divider (8) in the first cavity (31). The lower end of the flow divider (8) protrudes outward from the connector (3) and is inserted into the gear pump (5). The flow splitter (8) comprises a cylindrical portion (81) and conical portions (82) arranged at both ends of the cylindrical portion (81); at least one annular groove (83) is arranged on the surface of the cylindrical portion (81) along its circumference; a preset number of strip grooves (84) are also arranged on the surfaces of the cylindrical portion (81) and the conical portion (82); each strip groove (84) is connected to the annular groove (83); the strip grooves (84) on the surface of the conical portion (82) are all gathered at the end of the conical portion (82); the annular groove (83) divides the flow splitter (8) into at least two parts; the strip grooves (84) on the surfaces of the flow splitters (8) of adjacent parts are arranged alternately in the vertical direction.

2. The wood plastic physical micro-foaming extrusion injection molding machine according to claim 1, characterized in that: The twin-screw extruder (1) and the injection mechanism (6) are arranged in parallel, and the injection mechanism (6) is arranged directly below the twin-screw extruder (1).

3. The wood plastic physical micro-foaming extrusion injection molding machine according to claim 1, characterized in that: The gear pump (5) comprises a gear pump housing (51), wherein two gear shafts (52) are arranged in the gear pump housing (51), the two gear shafts (52) are arranged in parallel in a horizontal shape and mesh with each other, the second gear shaft (522) is arranged directly below the first gear shaft (521), the upper end of the gear pump housing (51) is connected to the connecting body (3) as an input end, and the lower end of the gear pump housing (51) is connected to the injection cylinder front body (62) as an output end.

4. The wood plastic physical micro-foaming extrusion injection molding machine according to claim 1, characterized in that: The check valve (7) comprises a valve housing (71) and a ball (72); the top end of the valve housing (71) is arranged as an input end, the bottom end of the valve housing (71) is arranged as an output end, and the ball (72) adapted to the output port is arranged in the valve housing (71).

5. The molding process using the injection molding machine according to claim 1, characterized in that: The steps include: 1) The raw materials include a mixed powder consisting of polyethylene, wood powder, additives and supercritical gas; 2) The mixed powder is heated and mixed evenly, and then cooled, and the mixed powder enters the barrel through the hopper, and is mixed, plasticized and extruded in a twin-screw extruder to obtain a melt; 3) The melt enters the connector through the barrel precursor and is preliminarily mixed with the supercritical gas from the supercritical fluid injector in the first cavity; 4) Under the action of the gear pump, the melt and the supercritical fluid are evenly mixed to obtain a stable melt polymer; 5) The molten polymer is injected into the mold cavity, and after low-pressure filling, the gas bubbles grow until the cavity is filled, completing the product molding.

6. The molding process according to claim 5, characterized in that: The additives consist of color powder, coupling agent, internal lubricant and external lubricant.

7. The molding process according to claim 6, characterized in that: The weight ratio of the raw materials: Polyethylene 50-60 Wood powder 29-44 Color powder 1-2 Coupling agent 3-5 Internal lubricant 0.5-1 External lubricant 0.5-1 Supercritical gases 1-2.

8. The molding process according to claim 6, characterized in that: The coupling agent is maleic anhydride, the internal lubricant is stearic acid, the external lubricant is PE wax, and the supercritical gas is nitrogen or carbon dioxide.

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