Thermoplastic resin molding manufacturing apparatus and thermoplastic resin molding manufacturing method

Abstract

The present invention provides an apparatus and method for manufacturing a thermoplastic resin molded product, which are capable of easily manufacturing small quantities of parts. [Solution] The thermoplastic resin molded product manufacturing apparatus disclosed in the present application includes a first pressurizer that pressurizes a mold filled with thermoplastic resin in an amount equal to or greater than the volume of the molded product at a first temperature and a first pressure, and a second pressurizer that pressurizes the mold pressurized by the first pressurizer at a second temperature lower than the first temperature and a second pressure higher than the first pressure. The thermoplastic resin molded product manufacturing method disclosed in the present application is a method that fills a mold with thermoplastic resin in an amount equal to or greater than the volume of the molded product, pressurizes the mold filled with thermoplastic resin at a first temperature and a first pressure, and pressurizes the mold after pressing at the first temperature and the first pressure at a temperature lower than the first temperature and a second pressure higher than the first pressure.

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for manufacturing a resin molded product, and more particularly to an apparatus and method for manufacturing a thermoplastic resin molded product that are capable of manufacturing a molded product using a thermoplastic resin (thermoplastic resin molded product). [Background technology]

[0002] Injection molding has traditionally been widely used to manufacture molded products using thermoplastic resins. Injection molding is a method in which molten thermoplastic resin (molten resin) is poured into a mold to obtain a molded product with a shape that is the inverse of the mold, and a heated cylinder is used to melt the resin.

[0003] Thermoplastic resins are materials that experience a large change in specific volume within the range from their glass transition point to their melting point, and once they exceed their glass transition point, their volume increases rapidly, reaching a maximum near their melting point, and once they exceed their melting point, they change phase from solid to liquid. Injection molding is a technique that takes advantage of these properties of thermoplastic resins to obtain the desired molded product by melting, filling, holding pressure, and cooling the resin.

[0004] To shape thermoplastic resins using this method, it is first necessary to convert the solid material (such as pellets) into a liquid (melting process). The specific volume of the molten resin in the liquid phase increases discontinuously compared to the resin before the glass transition point.

[0005] After the material is in the liquid phase, this molten resin with a large specific volume is poured into a mold and shaped into the desired shape (shaping process (injection filling process)). When the shaped thermoplastic resin is cooled, its specific volume changes significantly and it shrinks, so the desired shape cannot be obtained by simply pouring the molten resin into a mold.

[0006] Therefore, while the molten resin is cooling from its solidification point to its glass transition point, it is necessary to constantly replenish the mold with resin to compensate for the shrinkage.In injection molding, strong pressure is continuously applied from the cylinder, and the shape of the molded product is maintained by replenishing resin to compensate for the shrinkage (holding pressure process).

[0007] When a resin is cooled to a temperature below its glass transition point, the rate of decrease in specific volume becomes linear, so deformation is unlikely to occur when the shaped product is removed from the mold (cooling process, removal process). Generally, when removing the product, it is cooled to a temperature below the glass transition point, at which workability can be expected.

[0008] In this way, in the injection molding method, the thermoplastic resin is shaped through five steps: melting, shaping (injection filling), pressure holding, cooling, and removal, to obtain a molded product of the desired shape.

[0009] Conventionally, a known injection molding device used in injection molding is one in which resin is poured into a heating cylinder and gradually melted while being transported to the tip by a screw, and the molten resin is extruded from an extrusion injection nozzle at the tip of the heating cylinder and extruded into an injection mold (Patent Document 1). [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-131966 Summary of the Invention [Problem to be solved by the invention]

[0011] However, injection molding has drawbacks, such as the need to clean each time the material is changed, the molds are expensive, and it takes time to master the technique, making it unsuitable for the simple manufacture of small quantities of parts using thermoplastic resins.

[0012] The present invention has been made in consideration of the above circumstances, and the problem to be solved by the present invention is to provide a thermoplastic resin molding manufacturing apparatus and a thermoplastic resin molding manufacturing method that can easily manufacture small quantities of parts using thermoplastic resin. [Means for solving the problem]

[0013] The inventors of the present invention believe that one of the causes of the above-mentioned problems lies in the use of a heating cylinder, and after extensive research, have developed the thermoplastic resin molding manufacturing apparatus and thermoplastic resin molding manufacturing method disclosed in the present application as a means of not using a heating cylinder.

[0014] [Thermoplastic resin molded product manufacturing equipment] The thermoplastic resin molded product manufacturing apparatus disclosed in the present application includes a first pressurizer that pressurizes a mold filled with thermoplastic resin in an amount equal to or greater than the volume of the molded product at a first temperature and a first pressure, and a second pressurizer that pressurizes the mold pressurized by the first pressurizer at a second temperature lower than the first temperature and a second pressure higher than the first pressure.

[0015] [Thermoplastic resin molded product manufacturing method] The method for producing a thermoplastic resin molded product disclosed in the present application is a method in which a mold is filled with a thermoplastic resin in an amount equal to or greater than the volume of the molded product, the mold filled with the thermoplastic resin is pressurized at a first temperature and a first pressure, and the mold after being pressurized at the first temperature and the first pressure is pressurized at a second temperature lower than the first temperature and a second pressure higher than the first pressure. [Effects of the Invention]

[0016] According to the thermoplastic resin molded product manufacturing apparatus and the thermoplastic resin molded product manufacturing method disclosed in the present application, it is possible to easily manufacture a small number of parts using thermoplastic resin. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a front view showing an example of an apparatus for producing a thermoplastic resin molded product. [Figure 2](a) is a view taken along the line IIa-IIa in Figure 1, and (b) is a view taken along the line IIb-IIb in Figure 1. [Figure 3] (a) is an explanatory diagram of the state where the die is on the elliptical roll, and (b) is an explanatory diagram of the state where the die is on the lower plate. [Figure 4] FIG. 1( a ) is an explanatory diagram of a process of transferring a mold to a predetermined position in a first pressurizer, and FIG. 1( b ) is an explanatory diagram of a process of pressurizing the mold with the first pressurizer. [Figure 5] FIG. 1( a ) is an explanatory diagram of the process of transferring the mold to a predetermined position in the second pressurizer, and FIG. 1( b ) is an explanatory diagram of the process of pressurizing the mold with the second pressurizer. [Figure 6] FIG. 10 is an explanatory diagram of a step of sending out the mold from the second pressurizer. [Figure 7] (a) is an explanatory diagram of the state in which the mold is set in a predetermined position in the first pressurizer, (b) is an explanatory diagram of the state of the thermoplastic resin when the mold is pressurized by the first pressurizer, and (c) and (d) are explanatory diagrams of the change in the state of the thermoplastic resin when the mold is cooled by the second pressurizer. DETAILED DESCRIPTION OF THE INVENTION

[0018] (Embodiment) An example of an embodiment of the present invention will be described with reference to the drawings. The thermoplastic resin molding manufacturing apparatus (hereinafter simply referred to as "manufacturing apparatus") of this embodiment is an apparatus capable of realizing resin shaping using a thermoplastic resin.

[0019] 1 to 3(a) and (b) show an example of a manufacturing apparatus that includes a first pressurizing device 10, a second pressurizing device 20, and a mold transfer device 30. In this embodiment, the first pressurizing device 10 and the second pressurizing device 20 are arranged side by side at the same height, and the mold transfer device 30 is provided so as to straddle both of them.

[0020] <First pressurizer> The first pressurizer 10 is a compression mechanism that pressurizes a mold M filled with a volume of thermoplastic resin equal to or greater than the volume of the molded product at a first temperature and a first pressure, and is equipped with an upper plate (hereinafter referred to as the "first upper plate") 11 and a lower plate (hereinafter referred to as the "first lower plate") 12 that are arranged facing each other with a gap in the vertical direction. The first upper plate 11 and the first lower plate 12 cooperate to sandwich the mold M, and together they function as a single clamping tool (first clamping tool).

[0021] An air cylinder 13 is connected to the first upper plate 11, and the first upper plate 11 is configured to move up and down by the power of the air cylinder 13. Something other than an air cylinder can also be used to drive the first upper plate 11. A guide support (hereinafter referred to as the "first guide support") 14 is provided between the first upper plate 11 and the first lower plate 12 to guide the first upper plate 11 as it moves up and down.

[0022] The first upper plate 11 and the first lower plate 12 of the first pressurizer 10 are adapted to be able to adjust to a predetermined resin melting temperature by a temperature regulator (first temperature control device) or the like. The temperature regulator may be an electric heater or a medium circulation type temperature regulator that regulates the temperature by circulating a medium such as oil or steam.

[0023] The first pressurizer 10 is a mechanism for heating and melting the thermoplastic resin filled in the mold M, and is configured to continuously press the mold M sandwiched therein under a low pressure (first pressure) while heating it. The low pressure (first pressure) referred to here is 1 kgf / cm 2 This means a pressure equal to or greater than the second pressure, which will be described later. However, this value is an example, and the first pressure may vary depending on the viscosity of the material when melted, the size of the molded product, and the mold. 2 It can also be less than.

[0024] In the first pressurizer 10, when pressurizing, the resin in the mold M is in close contact with the inner surface of the mold M, and the pressure is applied to the extent that the outer surface of the mold M is in close contact with the first upper plate 11 and the first lower plate 12, so that the heat from the heated first upper plate 11 and first lower plate 12 can be transferred to the mold M.

[0025] The first pressurizer 10 may be provided with a mechanism (first pressure control device) that automatically releases the pressure applied by the first upper plate 11 and the first lower plate 12 when heating and pressurization are completed (i.e., when the thermoplastic resin has completely melted). In this case, for example, it may be determined that heating and pressurization have been completed when a preset time has elapsed, and the pressure applied by the first upper plate 11 and the first lower plate 12 may be automatically released.

[0026] The end of heating and pressurization can also be determined by other methods. For example, when the density of the thermoplastic resin in the mold M changes due to melting, the closing depth of the mold (the width of the gap between the upper mold M1 and the lower mold M2) changes, so the end of heating and pressurization can be determined based on the width of the gap between the upper mold M1 and the lower mold M2.

[0027] Specifically, the gap between the upper mold M1 and the lower mold M2 is photographed with a camera or the like, and when the width of the gap becomes less than a preset threshold, it is determined that heating and pressurization have ended, and the pressure applied by the first upper plate 11 and the first lower plate 12 is automatically released.

[0028] <Second pressurizer> The second pressurizer 20 is a compression mechanism that pressurizes the mold M at a second temperature lower than the first temperature and at a second pressure higher than the first pressure, and includes an upper plate (hereinafter referred to as the "second upper plate") 21 and a lower plate (hereinafter referred to as the "second lower plate") 22 that are arranged facing each other with a gap in the vertical direction. The second upper plate 21 and the second lower plate 22 cooperate to sandwich the mold M, and together they function as a single clamping tool (second clamping tool).

[0029] A hydraulic cylinder 23 is connected to the second upper plate 21, and the second upper plate 21 is configured to move up and down by the power of the hydraulic cylinder 23. Something other than a hydraulic cylinder can also be used to drive the second upper plate 21. A guide support pillar (hereinafter referred to as the "second guide support pillar") 24 is provided between the second upper plate 21 and the second lower plate 22 to guide the second upper plate 21 as it moves up and down.

[0030] Like the first upper plate 11 and the first lower plate 12, the second upper plate 21 and the second lower plate 22 can also be adjusted to a predetermined cooling temperature by a temperature regulator (second temperature control device) or the like. The temperature regulator may be a medium circulation type temperature regulator that regulates the temperature by circulating a medium such as water, oil, or steam. The temperature regulator may be shared with the temperature regulator for the first upper plate 11 and the first lower plate 12, or a different temperature regulator may be used.

[0031] The second pressurizer 20 is a mechanism for compressing and cooling the thermoplastic resin, and is configured to continuously apply high pressure (second pressure) to the mold M while rapidly cooling the mold M. The high pressure (second pressure) referred to here is 20 kgf / cm. 2 However, this value is an example, and the second pressure is 20 kgf / cm 2 It can also be less than.

[0032] In the second pressurizer 20, the outer surface of the mold M is in close contact with the cooled second upper plate 21 and second lower plate 22 so that the mold M can be cooled by the cooled second upper plate 21 and second lower plate 22 during pressurization, and a pressure is applied to the extent that the molten resin in the mold M is in close contact with the inner surface of the mold M (to the extent that the mold M is clamped).

[0033] Like the first pressurizing device 10, the second pressurizing device 20 may also be provided with a mechanism (second pressure control device) that automatically releases the pressure applied by the second upper plate 21 and the second lower plate 22 when the cooling and pressurizing are completed. In this case, for example, it may be determined that the cooling and pressurizing are completed when a preset time has elapsed, and the pressure applied by the second upper plate 21 and the second lower plate 22 may be automatically released. The determination of the completion of the cooling and pressurizing may also be made by other methods.

[0034] <Mold transfer machine> The mold transfer machine 30 is a carrier for transferring the mold M. The mold transfer machine 30 transfers the mold M filled with thermoplastic resin to a predetermined position in the first pressurizer 10, transfers the mold M after pressurization in the first pressurizer 10 to a predetermined position in the second pressurizer 20, and sends out the mold M from the predetermined position in the second pressurizer 20.

[0035] In this embodiment, two roller conveyors arranged in parallel with a gap between them are used as the mold transfer device 30. Each roller conveyor has supports 31a and 31b arranged opposite each other and a plurality of elliptical rolls 32 rotatably supported between the supports 31a and 31b. Adjacent elliptical rolls 32 are connected by a connecting member such as a belt so that the plurality of elliptical rolls 32 rotate synchronously by a single drive source (not shown).

[0036] As shown in Figures 2(a) and 2(b), in this embodiment, two grooves 12a and 22a are formed in each of the first lower plate 12 and the second lower plate 22, and one roller conveyor is accommodated in each groove 12a and 22a.

[0037] 3(a) and 3(b), the mold M transported by the mold transport device 30 is separated from the first lower plate 12 and the second lower plate 22 when the elliptical roll 32 is oriented vertically, and is supported by the first lower plate 12 and the second lower plate 22 when the elliptical roll 32 is oriented horizontally. Therefore, by oriented horizontally, the mold M can be pressed without interference from the elliptical roll 32.

[0038] The configuration of this embodiment is merely an example, and the manufacturing apparatus of the present invention is not limited to the configuration of the embodiment. The manufacturing apparatus of the present invention can be appropriately modified, such as by adding, replacing, or omitting components, within the scope of achieving the intended purpose.

[0039] For example, in this embodiment, from the viewpoint of thermal efficiency, the first pressurizer 10 and the second pressurizer 20 are installed separately on different tables, but the first pressurizer 10 and the second pressurizer 20 can also be installed on a single table.

[0040] In addition, in the above embodiment, an example is given in which the first pressurizer 10 and the second pressurizer 20 are arranged side by side, but the arrangement of the first pressurizer 10 and the second pressurizer 20 may be other than this, for example, the first pressurizer 10 and the second pressurizer 20 may be arranged opposite each other.

[0041] In addition, in the above embodiment, an example is given in which the mold transfer device 30 is composed of two roller conveyors each equipped with an elliptical roll 32, but the mold transfer device 30 can also be equipped with a roller conveyor equipped with a cylindrical roll (with a cross-sectional shape that is circular or approximately circular).

[0042] In this case, the mold transporter 30 is not designed to fit into the grooves 12a, 22a of the first lower plate 12 and the second lower plate 22, but can be installed in front of the first pressurizer 10 and the second pressurizer 20 arranged side by side.

[0043] In such a configuration, it is necessary to provide a mechanism for sending the mold M from the mold transfer machine 30 to a predetermined position in the first pressurizer 10 or the second pressurizer 20, and a mechanism for sending the mold M from a predetermined position in the first pressurizer 10 or the second pressurizer 20 to the mold transfer machine 30.

[0044] In addition, in the above embodiment, an example is given in which the first pressurizer 10 is equipped with the first guide support 14 and the second pressurizer 20 is equipped with the second guide support 24, but the first pressurizer 10 and the second pressurizer 20 can also be press machines (so-called C-type press machines) that do not have supports corresponding to the first guide support 14 and the second guide support 24.

[0045] In this case, in addition to the various structures described above, a ball screw may be used for the mold transporter 30. Specifically, a mold pressing tool may be attached to the nut of the ball screw, and the mold M may be transported by the mold pressing tool.

[0046] Next, a method for manufacturing a thermoplastic resin molded product (hereinafter simply referred to as "manufacturing method") will be described. Here, a case where a thermoplastic resin molded product is manufactured using the manufacturing apparatus of this embodiment will be taken as an example.

[0047] (1) First, thermoplastic resin (pellets) is poured into the space between the upper mold M1 and the lower mold M2 that make up the mold M. To obtain a sufficient pressure holding effect, the amount of thermoplastic resin poured into the mold M is equal to or greater than the volume of the product (for example, approximately 105 to 120% of the volume of the product). (2) The mold M into which the thermoplastic resin has been poured is transferred by the mold transfer device 30 to a predetermined position between the first upper plate 11 and the first lower plate 12 of the first pressurizer 10 (FIG. 4(a)). (3) After the mold M is transferred to a predetermined position in the first pressurizer 10, the first upper plate 11 is pressed down by the air cylinder 13, and the mold M is pressurized and heated by the first upper plate 11 and the first lower plate 12 (FIG. 4(b)). At this time, the upper mold M1 and the lower mold M2 of the mold M are not completely closed, and are pressurized to the extent that a gap remains between them. In addition, the temperatures of the first upper plate 11 and the first lower plate 12 are adjusted to a temperature slightly higher than the melting temperature of the pellets inside the mold M so that the pellets inside the mold M can be melted. (4) After the pressurization and heating in the first pressurizer 10 is completed, the pressure on the mold M by the first upper plate 11 and the first lower plate 12 is released, and the mold M is transferred by the mold transfer device 30 to a predetermined position between the second upper plate 21 and the second lower plate 22 of the second pressurizer 20 (Figure 5(a)). (5) After the mold M is transferred to a predetermined position in the second pressurizer 20, the second upper plate 21 is pressed down by the hydraulic cylinder 23, and the mold M is pressurized and cooled by the second upper plate 21 and the second lower plate 22 (FIG. 5(b)). At this time, the upper mold M1 and the lower mold M2 of the mold M are pressurized to the extent that they are completely closed. In addition, the second upper plate 21 and the second lower plate 22 are, in principle, temperature-controlled so that the temperature of the molded product inside the mold M is below the glass transition point. (6) After the pressurization and cooling in the second pressurizer 20 is completed, the pressure on the mold M by the second upper plate 21 and the second lower plate 22 is released, and the mold M is ejected beyond the second pressurizer 20 by the mold transfer device 30 (Figure 6). (7) After the mold M is ejected beyond the second pressurizer 20, the upper mold M1 and lower mold M2 of the ejected mold M are opened to remove the molded product inside, and finishing work is carried out to complete the molded thermoplastic resin product.

[0048] In the above manufacturing process, as shown in Figures 7(a) and (b), in the first pressurizer 10, the mold M is heated while being sandwiched between the first upper plate 11 and the first lower plate 12 under weak pressure (first pressure), and the heated thermoplastic resin is melted together with the mold M. By squeezing at low pressure, the molten resin is gradually filled into the voids inside the mold. When the entire thermoplastic resin is melted, the resin is melted and shaped by the mold.

[0049] In the first pressurizer 10, the heated first upper plate 11 and first lower plate 12 are kept in close contact with the outer peripheral surface of the mold M, so that heat is transferred to the mold M, and the thermoplastic resin inside the mold M gradually melts due to the heat. However, because the pressure is weak, the mold M does not close completely even if all the thermoplastic resin inside has melted.

[0050] 7(c) and (d), in the second pressurizing device 20, the mold M after the completion of melting and shaping in the first pressurizing device 10 is cooled while being sandwiched under strong pressure (second pressure) between the second upper plate 21 and the second lower plate 22. At this time, the excess molten resin in the mold M seeps out due to the high pressure squeezing. Pressure retention and cooling are performed by the operation of the second pressurizing device 20.

[0051] At the stage when the mold M is transferred to the second pressurizer 20, the inside of the mold M is filled with molten resin whose temperature is slightly above its melting point, and the mold M in this state is rapidly cooled and its temperature is lowered by coming into contact with the second upper plate 21 and the second lower plate 22 of the second pressurizer 20. At this time, the molten resin inside is cooled in order from the part in contact with the mold M (the part in contact with the inner peripheral surface of the mold), but because the temperature of the molten resin is near its melting point, its specific volume rapidly decreases and it contracts.

[0052] The resin closer to the mold M has a smaller specific volume and a higher viscosity, resulting in lower fluidity. On the other hand, the resin further away from the mold M has a larger specific volume and lower viscosity. For this reason, the molten resin inside, which has a higher temperature and higher fluidity, tries to flow out of the mold M, but as it does so, the resin with higher fluidity fills in the underfilled areas while the excess flows out. As a result, the resin solidifies due to cooling inside the mold M, and pressure is maintained by filling in the contracted areas with material.

[0053] (Comparison with conventional technology) There is a compression molding machine used for thermosetting rubber that is similar in appearance to the manufacturing apparatus of this embodiment. However, the compression molding machine is a machine designed to shape thermosetting rubber, which is cross-linked by heating and does not deform after cross-linking, and its purpose and function are essentially different from those of the manufacturing apparatus of this embodiment. In particular, it does not have a structure that satisfies the function of pressure retention.

[0054] In addition, since thermoplastic rubber is a soft material, even if it is squeezed with strong pressure before melting, it will not damage the mold, and the strength of the pressure is sufficient as long as it is strong enough to close the mold, so there is no need to use different pressures. Also, since crosslinking and hardening proceeds simply by heating, there is no need to consider the cooling function to remove the shaped molded product inside.

[0055] As such, there are clear functional differences between the manufacturing apparatus of this embodiment and conventional compression molding apparatuses, and therefore the novelty and inventive step of the manufacturing apparatus disclosed in this application cannot be denied based on the conventional compression molding apparatus.

[0056] Furthermore, a heat and cool molding method is known as one of the conventional injection molding methods. The heat and cool molding method is merely one form of injection molding, and differs from the manufacturing apparatus of this embodiment in that melting and pressure holding are performed using a cylinder.

[0057] As such, there are clear functional differences between the manufacturing apparatus of this embodiment and the heat and cool molding method, and the novelty and inventive step of the manufacturing apparatus disclosed in this application cannot be denied based on the conventional heat and cool molding method.

[0058] (Effects of the manufacturing apparatus of this embodiment) In conventional injection molding, the thermoplastic resin is melted in a heated cylinder while the internal rotating screw rotates to destroy the resin. While this method is suitable for efficiently melting thermoplastic resin, it is prone to overshooting due to the synergistic effect of the shear heat generated when the resin breaks down and the heated cylinder, making heat control difficult.

[0059] In contrast, in the manufacturing apparatus of this embodiment, temperature control is performed solely by the heating mechanism of the apparatus, so shear heat does not occur and the resin melting temperature can be accurately controlled. Because a temperature slightly above the melting point of the thermoplastic resin can be maintained, there is no risk of the thermoplastic resin in the mold M becoming excessively hot and deteriorating the material, and unlike injection molding, technical proficiency in the resin melting process is not required as much.

[0060] In injection molding, the molten resin must be filled into the mold in a short time, so the resin must be completely melted to ensure sufficient fluidity. This often means that the resin is heated to temperatures well above its melting point, which can often cause deterioration of the thermoplastic resin.

[0061] In contrast, in the method using the manufacturing apparatus of this embodiment, the molded product is shaped at around the melting point of the resin and is unlikely to be heated much above this point, so deterioration of the thermoplastic resin is unlikely to occur.

[0062] In injection molding, molten resin is filled into a mold in a short time under high pressure, which tends to leave residual stress inside the molded product. It is particularly difficult to prevent long, flat plates from warping in one direction.

[0063] In contrast, in the method using the manufacturing apparatus of this embodiment, melting and cooling are carried out uniformly, and residual stress during filling is unlikely to occur, so that the resulting molded product is unlikely to warp or distort.

[0064] Generally, thick shapes are avoided in injection molding of thermoplastic resins. In injection molding, the surface that comes into contact with the mold solidifies instantly, but no resin is added to the thick interior to compensate for shrinkage, so as the interior solidifies and shrinks, it can pull on the solidified surface, causing dents (sink marks) and vacuum bubbles.

[0065] In contrast, in the method using the manufacturing apparatus of this embodiment, resin is continuously supplied to the inside of the molded product and pressure is maintained until the temperature drops below the solidification point, so sink marks and vacuum bubbles are less likely to occur even in thick-walled products, and it is possible to mold molded products without sink marks or vacuum bubbles.

[0066] Generally, in injection molding of thermoplastic resins, uneven thickness shapes with a mixture of thick and thin sections are avoided because they are prone to deformation and sink marks due to the different timing between filling and solidification shrinkage.

[0067] In contrast, with the method using the manufacturing apparatus of this embodiment, the entire mold is melted and filled at the same time regardless of thickness, so there are no problems with filling, and the resin is evenly replenished and pressure is applied throughout the mold, so insufficient filling, sink marks, and distortion are unlikely to occur.

[0068] In general, in most injection molding processes, filling and holding pressure are carried out within an extremely short time of less than one second. The composition of the entire molded product is determined by how this timing is set, so every moment of this process must be controlled by the injection molding machine. Mastering this skill is difficult, and it is said to take 5 to 10 years to become a top-class molding technician.

[0069] In contrast, the method using the manufacturing apparatus of this embodiment does not have any problems with melting and filling, and at the same time, there is a time lag of several tens of seconds for the solidification and shrinkage process, so molding skills can be acquired more easily than with the injection molding method.

[0070] In injection molding, every time the mold is changed, all the resin in the heating cylinder must be extruded and replaced with new resin. This is an extremely tedious process and requires a large amount of material to clean the heating cylinder.

[0071] In contrast, in the method using the manufacturing apparatus of this embodiment, the resin exists only within the mold, so in principle, cleaning is not required. Therefore, it is possible to change the filler material for each shot without special cleaning, and there is no need for setup. As a result, multi-color single-item production, which is almost impossible with injection molding, can be easily performed.

[0072] In injection molding, in order to prevent the mold from deforming under the high pressure of filling, a mold body that is much larger than the molded object itself is used, and the mold is made from high-strength mold steel that can withstand strong pressure. Careful consideration must also be given to the flow path of the resin, so the mold cost is extremely high.

[0073] In contrast, the mold used in the method using the manufacturing apparatus of this embodiment is clamped between compression devices and does not require high rigidity like the mold used in injection molding. Furthermore, since it does not need to withstand the high-speed intrusion of resin, it does not require the strength of injection molding mold steel, and soft materials such as aluminum are not an issue. In fact, it is preferable to make the mold thin to increase thermal conductivity, which significantly reduces mold costs. This makes it suitable for small-lot production, where amortization of initial costs is difficult.

[0074] With injection molding, film insert molding is considered difficult, and it is particularly difficult to integrally mold thin films over large areas. This is because a high level of know-how is required to design the resin flow path so that the film does not break or deform when exposed to high-speed, high-pressure resin.

[0075] In contrast, in the method using the manufacturing apparatus of this embodiment, excessive pressure is unlikely to be applied to the film due to the resin flow, so such film insertion can be easily performed.

[0076] With injection molding, there are very few cases where fibers or fabrics are inserted and molded into a single piece in one go. Injection molding fills the resin at high speed and pressure, so even if the fibers or fabrics are inserted inside the mold, it is difficult to fill the resin without moving them from the initial fixed position, which is one reason why it is difficult to evenly integrate the fibers or fabrics with the resin.

[0077] Furthermore, with injection molding, which fills at high speed and solidifies instantly, it is difficult to fill the voids in the fibers or fabric with resin without any gaps and integrate them into one piece. For this reason, the only materials that have been put into practical use for injection molding are those in which short fibers are kneaded into resin pellets and then injected into regular molding.

[0078] However, it is known that by making composites of fibers and textiles in their original state, the strength and toughness of the resin molded product can be dramatically improved, so there is an extremely high demand for such materials.

[0079] In contrast, in the method using the manufacturing apparatus of this embodiment, it is difficult to generate forces that move the fabric or fibers from their designated positions in the mold, and the force is easy to control. In addition, the resin fills between the fibers during a long dwell time, which increases adhesion, so that the fibers and fabric can be easily molded into one piece without using any particularly difficult methods to fix them.

[0080] Regardless of the injection molding method, when different types of plastics are molded together, the two often do not bond well together. When injection molding is performed, the resin fills the mold in a flow pattern known as fountain flow, which creates a surface skin layer and an internal core layer. The skin layer, which is relatively cold, is difficult to bond to the insert. The mating insert part is also cold and molecularly inactive, making it difficult for sufficient adhesion or intermolecular forces to work, even when the two parts come into contact under high pressure for a short period of time.

[0081] In contrast, when inserting using the manufacturing apparatus of this embodiment, the insert is heated to a certain temperature or higher, and the molten resin is pressed against it in a molecularly activated state for a certain period of time. This results in sufficient adhesion between the two, and not only is there intermolecular force acting, but they are also bonded by the anchor effect. This makes it possible to bond resins that do not bond well with injection molding with extremely high strength.

[0082] The effects exemplified here are effects that can be achieved by the manufacturing apparatus of this embodiment, but not all of these effects are always achieved. The manufacturing apparatus of the present invention also includes those that do not achieve these effects.

[0083] The embodiments and modifications disclosed in this application are merely examples and are not intended to limit the scope of the present invention. The technical scope of the present invention is defined by the claims. The technical scope of the present invention also includes equivalents to the claims. [Industrial Applicability]

[0084] The manufacturing apparatus and manufacturing method of the present invention can be used for molding various resins, and can be particularly suitably used for manufacturing molded articles using thermoplastic resins. [Explanation of symbols]

[0085] 10 First pressurizer 11 Upper plate (first upper plate) 12 Lower plate (first lower plate) 12a groove 13 Air cylinder 14 Guide post (first guide post) 20 Second pressurizer 21 Upper plate (second upper plate) 22 Lower plate (second lower plate) 22a groove 23 Hydraulic cylinder 24 Guide post (second guide post) 30 Mold transfer machine 31a, 31b Support 32 oval roll M mold M1 upper mold M2 lower mold

Claims

1. In an apparatus for manufacturing molded products using thermoplastic resin, a first pressurizer that applies a first pressure to a mold filled with a pellet-shaped thermoplastic resin in an amount equal to or greater than the volume of a molded product, and heats the mold at a first temperature higher than the melting temperature of the thermoplastic resin to melt the thermoplastic resin in the mold; a second pressurizer that pressurizes the mold pressurized by the first pressurizer at a second pressure higher than the first pressure and cools the mold at a second temperature lower than the first temperature; When the mold is pressurized and cooled by the second pressurizer, the thermoplastic resin in the mold is solidified and the contracted portion of the thermoplastic resin that flows without solidifying in the mold is filled, thereby maintaining pressure inside the mold. A thermoplastic resin molding manufacturing apparatus characterized by:

2. 2. The apparatus for producing a thermoplastic resin molded product according to claim 1, a mold transfer device that transfers the mold filled with the thermoplastic resin to a predetermined position of a first pressurizer and transfers the mold after pressurization by the first pressurizer to a predetermined position of a second pressurizer; A thermoplastic resin molding manufacturing apparatus characterized by:

3. 2. The apparatus for producing a thermoplastic resin molded product according to claim 1, The first pressurizer includes a first clamping tool that clamps the mold, a first temperature control device that controls the temperature of the first clamping tool, and a first pressure control device that controls the pressure of the first clamping tool. A thermoplastic resin molding manufacturing apparatus characterized by:

4. 2. The apparatus for producing a thermoplastic resin molded product according to claim 1, The second pressurizer includes a second clamping tool that clamps the mold, a second temperature control device that controls the temperature of the second clamping tool, and a second pressure control device that controls the pressure of the second clamping tool. A thermoplastic resin molding manufacturing apparatus characterized by:

5. In a method for producing a molded product using a thermoplastic resin, Fill the mold with pelletized thermoplastic resin in an amount equal to or greater than the volume of the molded object, The mold filled with the thermoplastic resin is pressurized at a first pressure and heated at a first temperature higher than the melting temperature of the thermoplastic resin to melt the thermoplastic resin in the mold; The mold after being pressurized at the first temperature and the first pressure is pressed at a second pressure higher than the first pressure, and the mold is cooled at a second temperature lower than the first temperature; During the pressurization at the second pressure and the cooling at the second temperature, the thermoplastic resin in the mold is solidified and the contracted portion of the thermoplastic resin that flows without being solidified in the mold is filled, thereby maintaining pressure inside the mold. A method for producing a thermoplastic resin molded product, comprising:

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