Molding method and molding device

Abstract

To solve a problem that, depending on a type of molding material and a shape of a cured molded body, the cured molded body may remain in close contact with a surface of a mold and thus be difficult to release from the mold after curing.SOLUTION: In a molding method, a molded body 1 is molded using a mold 31 in which a cavity 33 is defined by clamping a first mold 321 and a second mold 341 that can be opened. Pressurized gas is introduced into the cavity 33 from a gas introduction hole 326 provided in the first mold 321, and while the pressurized gas is being introduced, plasticized molding material 11 is injected into the cavity 33.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a molding method and a molding apparatus. [Background technology]

[0002] Conventionally, as shown in Patent Document 1, a molding method has been disclosed in which molten resin is injected into a cavity of a mold to form a molded body, and then high-pressure air is sprayed into the cavity to release the molded body from the mold. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-117967 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the molding method described in Patent Document 1, depending on the type of molding material and the shape of the molded body after curing, the molded body may remain in close contact with the surface of the mold, which may make it difficult to release the molded body after curing. [Means for solving the problem]

[0005] The molding method is a molding method for molding a molded body using a mold in which a cavity is defined by clamping together a first mold and a second mold that can be opened, and in which pressurized gas is introduced into the cavity through a gas inlet hole provided in the first mold, and while the pressurized gas is being introduced, a plasticized molding material is injected into the cavity.

[0006] The molding device is a molding device comprising a mold in which a cavity is defined by clamping together first and second molds that can be opened, and a control unit that controls the molding operation, wherein the first mold has a gas inlet through which pressurized gas is introduced, and the control unit injects plasticized molding material into the cavity while introducing the pressurized gas into the cavity from the gas inlet. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a side view schematically showing an injection molding apparatus. [Figure 2] FIG. 2 is an exploded perspective view showing a schematic configuration of a mold. [Figure 3] Cross-sectional view taken along line AA in Figure 2. [Figure 4] 10 is a flowchart showing control of a molding method. [Figure 5] 4 is a timing chart showing control of a molding method. [Figure 6] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2 according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] 1. First embodiment ***Injection molding equipment overview*** 1 includes a material supply unit 10, an injection unit 20, a mold unit 30, a mold clamping unit 40, a control unit 50, a pressure unit 52, and an intake unit 54. The injection molding apparatus 100 forms a molded body 1 by molding a molding material 11 injected from the injection unit 20. The injection molding apparatus 100 is an example of a "molding apparatus."

[0009] The figures, including FIG. 1, show three mutually orthogonal axes: the X axis, the Y axis, and the Z axis. The X axis is an axis parallel to the installation surface of the injection molding apparatus 100. The +X direction, which is parallel to the X axis, is the direction from the back to the front of the injection molding apparatus 100 shown in FIG. 1. The -X direction is the opposite direction to the +X direction. The Y axis is an axis parallel to the installation surface of the injection molding apparatus 100 and perpendicular to the X axis. The +Y direction, which is parallel to the Y axis, is the direction from the injection unit 20 to the mold unit 30 of the injection molding apparatus 100 shown in FIG. 1. The -Y direction is the opposite direction to the +Y direction. The Z axis is an axis perpendicular to the installation surface of the injection molding apparatus 100. The +Z direction, which is parallel to the Z axis, is the direction upward from the installation surface. The -Z direction is the direction downward from the installation surface. When the installation surface of the injection molding apparatus 100 is a horizontal surface, the Z axis is an axis along the vertical direction.

[0010] The material supply unit 10 supplies the molding material 11, which is the raw material, to the injection unit 20. The material supply unit 10 is configured by, for example, a hopper. The molding material 11 supplied from the material supply unit 10 is in the form of pellets, powder, or the like. The molding material 11 supplied by the material supply unit 10 can be a resin such as ABS (acrylonitrile butadiene styrene), PP (polypropylene), PS (polystyrene), or elastomer.

[0011] The injection unit 20 plasticizes the molding material 11 supplied from the material supply unit 10. The injection unit 20 injects the plasticized molding material 11 from a nozzle (not shown) toward the mold unit 30. As the injection unit 20, for example, a screw-type injection unit may be used, or from the viewpoint of miniaturization, a small injection unit equipped with a disk-shaped flat screw formed with a spiral groove and a barrel facing the flat screw and having a communication hole in its center may be used.

[0012] Plasticization is a concept that includes melting, and refers to changing from a solid to a fluid state. In the case of a molding material 11 that undergoes glass transition, plasticization refers to raising the temperature of the molding material 11 to or above the glass transition point. In the case of a molding material 11 that does not undergo glass transition, plasticization refers to raising the temperature of the molding material 11 to or above the melting point.

[0013] The mold section 30 includes a mold die 31. The mold die 31 includes a first attachment portion 32 and a second attachment portion 34. A first die 321 is provided in the first attachment portion 32. A second die 341 is provided in the second attachment portion 34. A cavity 33 is defined in the mold die 31 by clamping the first die 321, which can be opened, and the second die 341, which faces the first die 321. The cavity 33 is a space corresponding to the shape of the molded body 1.

[0014] The plasticized molding material 11 injected from the injection section 20 flows into the cavity 33. The plasticized molding material 11 is cooled in the cavity 33. The plasticized molding material 11 is solidified by cooling. The solidification of the plasticized molding material 11 produces a molded body 1. Details of the mold section 30 will be described later.

[0015] The mold clamping unit 40 has a mold drive unit 42 and a mold clamping ball screw unit 44. The mold drive unit 42 is composed of a mold clamping drive motor, gears, etc. The mold drive unit 42 rotates the ball screw of the mold clamping ball screw unit 44. The mold clamping ball screw unit 44 converts rotational motion into linear motion. The mold clamping ball screw unit 44 transmits the power generated by the drive of the mold drive unit 42 to the first mounting unit 32.

[0016] The mold clamping unit 40 moves the first attachment unit 32 in the Y-axis direction using the mold drive unit 42 and the mold clamping ball screw unit 44. The mold clamping unit 40 opens and closes the mold 31, i.e., performs mold opening and mold clamping, by moving the first attachment unit 32. The mold clamping unit 40 clamps the mold 31 before the plasticized molding material 11 is injected into the cavity 33. The mold clamping unit 40 opens the mold 31 after the plasticized molding material 11 has solidified. When the mold clamping unit 40 opens the mold 31, the molded body 1 can be released from the mold.

[0017] The control unit 50 is configured, for example, by a computer having a processor, a memory unit, an input / output interface for inputting and outputting signals from and to the outside, an operation unit, and a display unit. The control unit 50 performs various functions by having the processor execute programs stored in the memory unit. The control unit 50 controls the molding operations performed by the injection unit 20, the mold clamping unit 40, the pressurizing unit 52, and the intake unit 54. The control unit 50 may be configured not by a computer but by a combination of multiple circuits.

[0018] The pressurizing unit 52 pressurizes the gas. For example, a compressor can be used as the pressurizing unit 52. The pressurizing unit 52 is connected to the first die 321 via a pressurized flow path 521 shown in FIG. 2. The pressurized flow path 521 located between the pressurizing unit 52 and the first die 321 is composed of a hose, a pipe, or the like. The pressurizing unit 52 introduces the pressurized gas into the cavity 33 through a gas introduction hole 326 shown in FIG. 2 that is provided in the first die 321. Details of the gas introduction hole 326 will be described later. The pressurized flow path 521 and the gas introduction hole 326 are not shown in FIG. 1.

[0019] Examples of pressurized gas include air, nitrogen, argon, and other gases that have a low risk of causing a chemical reaction with the molding material 11. The pressure of the pressurized gas is, for example, about 0.4 MPa, which is lower than the pressure at which the plasticized molding material 11 is injected from a nozzle (not shown). Therefore, molding defects such as concave shapes caused by the pressurized gas do not occur in the molded body 1.

[0020] The intake unit 54 draws in gas from an intake flow path 541 shown in FIG. 2. For example, a vacuum pump can be used as the intake unit 54. The intake unit 54 is connected to the first mold 321 via the intake flow path 541. The intake flow path 541, located between the intake unit 54 and the first mold 321, is composed of a hose, a pipe, or the like. The intake unit 54 applies negative pressure to the cavity 33 via a gas introduction hole 326 shown in FIG. 2 that is provided in the first mold 321. In other words, the pressurized flow path 521 and the intake flow path 541 are connected to each other inside the first mold 321 by a communication path 531, which will be described later.

[0021] ***Mold Overview*** 2 and 3, in the mold 31, the first attachment portion 32 and the first die 321 are connected by a fastening member such as a screw (not shown), and the second attachment portion 34 and the second die 341 are connected by a fastening member such as a screw (not shown). Note that the first attachment portion 32 and the second attachment portion 34 are not shown in FIG.

[0022] The first die 321 and the second die 341 may have a nested structure such as a split block or a solid block depending on the shape of the compact 1. In a preferred example, the die 31 is made of alloy tool steel, but is not limited to this and may be made of any hard metal such as steel, other metals, or alloys.

[0023] The first die 321 is primarily a convex movable die, and is provided with a die convex portion 322 that corresponds to the shape of the molded body 1. The die convex portion 322 protrudes in the -Y direction from the surface of the first die 321 that faces the second die 341. The die convex portion 322 has a die convex portion tip surface 323 and a die convex portion side surface 324. The die convex portion tip surface 323 has a surface that is along the XZ plane, and is formed at the -Y direction end of the die convex portion 322. The die convex portion side surface 324 is a surface that is generally along the Y axis and intersects with the XZ plane. The die convex portion tip surface 323 and the die convex portion side surface 324 form part of the cavity 33.

[0024] A gas vent 325 is provided on the -Y side surface of the first mold 321, i.e., the surface that comes into contact with the second mold 341 when the molds are clamped. The gas vent 325 is open to the atmosphere, and gas present in the mold 31 is discharged through the gas vent 325. The gas vent 325 has, for example, a groove shape. The depth of the groove facing the +Y direction of the gas vent 325 may be set appropriately depending on the consistency of the plasticized molding material 11, but is, for example, about 0.002 to 0.02 mm, a depth that does not cause flash to form on the molded body 1.

[0025] The first mold 321 has a gas inlet 326 through which pressurized gas is introduced. The gas inlet 326 is a hole provided in the mold convex tip surface 323, and is provided facing the +Y direction from the mold convex tip surface 323. A porous member 328, which allows gas to flow, is disposed at a position of the gas inlet 326 at least adjacent to the cavity 33. The pressurized gas is introduced into the cavity 33 via the porous member 328 provided in the gas inlet 326. In FIG. 3, the gas inlet 326 and the porous member 328 provided in the gas inlet 326 are hatched with vertical lines to clearly show the configuration.

[0026] The porous member 328 is formed, for example, by additive manufacturing, as disclosed in Japanese Patent Application Laid-Open No. 2020-203473. Examples of additive manufacturing include a manufacturing method in which a flat layer of metal powder material is irradiated with laser light to sinter the irradiated portion, and then a new layer of metal powder material is laid on top of that and irradiated with laser light, and this process is repeated. The porous member 328 can also be formed by subjecting sheet metal such as a stainless steel plate to punch pressing, dry etching, or wet etching. The porous member 328 formed by these manufacturing methods has fine through-holes, which can reduce the flow resistance that occurs when gas flows through it.

[0027] The size of the minute through-holes in the porous member 328 may be set appropriately depending on the consistency of the plasticized molding material 11. For example, the diameter of the through-holes may be set to 20 to 200 μm, the depth of the through-holes in the direction along the Y-axis to 2 mm, and the hole pitch of the through-holes to 250 to 350 μm. The porous member 328 may have any shape as long as it allows gas to pass through. For example, it may be a slit that penetrates along the Y-axis, or a so-called sponge-like member that is penetrated by a series of irregularly shaped holes.

[0028] The pressurized flow path 521 includes a valve (not shown) between the pressurizing unit 52 and the mold 31. This valve is opened and closed by the control unit 50. The introduction of pressurized gas into the cavity 33 is started or stopped by switching the opening and closing of the valve. Furthermore, the intake air flow path 541 includes a valve (not shown) between the intake unit 54 and the mold 31. This valve is opened and closed by the control unit 50. The application of negative pressure to the cavity 33 is started or stopped by switching the opening and closing of the valve.

[0029] A part of a pressurized flow path 521 connected to the pressurizing unit 52 is formed inside the first die 321. The pressurized flow path 521 is connected to a gas introduction hole 326 inside the first die 321. Also, a part of an intake flow path 541 connected to the intake unit 54 and a communication path 531 are formed inside the first die 321.

[0030] The intake air flow path 541 is connected to the communication path 531. The communication path 531 is a path that connects the intake air flow path 541 to the pressurized air flow path 521 inside the first mold 321. That is, the pressurized air flow path 521 and the intake air flow path 541 communicate with each other via the communication path 531 inside the first mold 321, and the pressurized air flow path 521 and the intake air flow path 541 also communicate with each other through the gas introduction hole 326. This makes it possible to introduce pressurized gas into the cavity 33 through the gas introduction hole 326, and to apply negative pressure to the cavity 33 through the gas introduction hole 326. The negative pressure is applied in the +Y direction, which is the same direction as the +Y direction in which the cured molded body 1 is released from the second mold 341. This makes it easy to hold the molded body 1 in the first mold 321 when the mold is opened.

[0031] The second mold 341 is a fixed mold that is mainly concave and corresponds to the shape of the molded product 1. The second mold 341 is formed with an injection hole 343 through which the plasticized molding material 11 is injected from a nozzle (not shown) provided in the injection unit 20. The injection hole 343 communicates with a sprue 342 provided in the second attachment unit 34 and is a hole that contacts the cavity 33. The plasticized molding material 11 is injected in the order of the nozzle (not shown), sprue 342, injection hole 343, and cavity 33. The surface of the cavity 33 in the second mold 341 is processed to have a draft angle and surface roughness required for releasing the molded product 1 from the second mold 341.

[0032] ***Flowchart overview of molding method*** The following describes a method for molding the molded article 1 using the injection molding apparatus 100. The subsequent operations are controlled by the control unit 50.

[0033] As shown in FIG. 4, first, in a mold clamping ON process of step S1, the mold 31 is clamped by the mold clamping unit 40. In a pressurized gas introduction ON process of step S2, pressurized gas pressurized by the pressurizing unit 52 is introduced into the cavity 33 from the gas introduction hole 326 provided in the first mold 321 via the pressurized distribution path 521. In a material injection process of step S3, the injection unit 20 injects the plasticized molding material 11 into the cavity 33 from the sprue 342. The material injection process of step S3 is performed in a state where pressurized gas is being introduced in the pressurized gas introduction ON process of step S2. In a pressurized gas introduction OFF process of step S4, the introduction of pressurized gas is stopped.

[0034] Next, in the intake ON process of step S5, the intake unit 54 applies negative pressure to the cavity 33 from the gas introduction hole 326 via the intake flow path 541. Next, in the mold clamping OFF process of step S6, the mold 31 is opened by the mold clamping unit 40. That is, after the material injection process of step S3 and before the mold clamping OFF process of step S6, the intake ON process of step S5 is performed.

[0035] After the mold clamping OFF process of step S6, i.e., after mold opening of the mold 31, the application of negative pressure to the cavity 33 by the intake unit 54 is stopped in the intake OFF process of step S7. Thereafter, the pressurized gas introduction ON process of step S8 is performed, in which pressurized gas is introduced into the cavity 33. This pressurized gas introduction ON process of step S8 is a process for releasing the molded body 1 from the first mold 321 by spraying pressurized gas onto the molded body 1. After the pressurized gas introduction ON process of step S8, the pressurized gas introduction OFF process of step S9 is performed.

[0036] Between before the pressurized gas introduction OFF step of step S4 and after the pressurized gas introduction OFF step of step S9, a metering step of step S10 is performed by the injection unit 20. The metering step of step S10 is a step of metering the molding material 11 required to mold the next molded body 1.

[0037] Next, in the mold release detection process of step S11, it is detected whether the molded body 1 has been released from the first mold 321. The mold release detection process of step S11 can be performed using a method in which an optical sensor detects the presence or absence of the molded body 1 in the first mold 321 that has been opened, but is not limited to this. As long as the presence or absence of the molded body 1 can be detected, methods such as image processing or a contact probe may also be used. Alternatively, the visual inspection results may be input to the control unit 50, and the mold release detection process of step S11 may be performed based on the results.

[0038] If it is detected in the mold release detection step of step S11 that the molded body 1 has been released from the first mold 321, that is, if the result of the mold release detection step of step S11 is "YES," the process proceeds to the production termination step of step S12. On the other hand, if it is not detected in the mold release detection step of step S11 that the molded body 1 has been released from the first mold 321, that is, if the result of the mold release detection step of step S11 is "NO," the process returns to the pressurized gas introduction ON step of step S8, and further introduces pressurized gas into the cavity 33. That is, the steps from the pressurized gas introduction ON step of step S8 to the mold release detection step of step S11 are repeated.

[0039] In the production termination process of step S12, if the production number of molded bodies 1 reaches the production target number, i.e., if the answer is "YES" in the production termination process of step S12, the production of the molded bodies 1 is terminated. On the other hand, in the production termination process of step S12, if the production number of molded bodies 1 does not reach the production target number, i.e., if the answer is "NO" in the production termination process of step S12, the process returns to the mold clamping ON process of step S1, and production continues until the production number of molded bodies 1 reaches the production target number.

[0040] *** Molding method timing chart overview *** Next, the molding method will be described using the timing chart shown in Fig. 5. Note that, among the timings T1 to T12 in Fig. 5, the larger the number, the later the timing. Furthermore, one cycle indicates the period required to produce one molded body 1, and this one cycle is repeated until the number of produced molded bodies 1 reaches the target production number.

[0041] The mold 31 is clamped during the period from timing T1 to timing T7. During the period from timing T2 to timing T5 during the clamping period, pressurized gas is introduced into the cavity 33 from a gas inlet hole 326 provided in the first mold 321. During the period from timing T3 to timing T4 during which the pressurized gas is introduced, plasticized molding material 11 is injected into the cavity 33 from a nozzle (not shown) provided in the injection unit 20 through a sprue 342 and an injection hole 343.

[0042] Furthermore, suction by the suction section 54 begins at timing T6, which is prior to timing T7 when the molds are opened, and stops at timing T8, which is after timing T7. From timing T9 to timing T10 after suction has stopped, pressurized gas for releasing the molded body 1 is introduced into the cavity 33 from the gas inlet hole 326. Thereafter, from timing T11 to timing T12, it is detected whether the molded body 1 has been released from the first mold 321. As described above, the weighing is performed during the period from timing T5 to timing T10.

[0043] As described above, the molding method and injection molding apparatus 100 of the first embodiment can provide the following effects. According to this embodiment, pressurized gas is introduced into the cavity 33 through the gas introduction hole 326 provided in the first mold 321, and while the pressurized gas is being introduced, the plasticized molding material 11 is injected into the cavity 33, so that the pressurized gas can promote the formation of a skin layer on the surface of the plasticized molding material 11.

[0044] The skin layer is a layer formed in the early stage of hardening of the surface of the plasticized molding material 11. Because the skin layer is a layer on the surface of the molding material 11 that has begun to harden, it has the property of lowering the mold release resistance against the surface of the cavity 33. Then, as the molding material 11 having the skin layer is filled into the cavity 33, it is possible to prevent the molded body 1 after hardening from adhering to the mold 31. This makes it easier to release the molded body 1 after hardening from the mold 31.

[0045] According to this embodiment, after the molding material 11 is injected and before the mold 31 is opened, a negative pressure is applied to the cavity 33 through the gas inlet hole 326 provided in the first mold 321. This causes the molded body 1 to be sucked into the first mold 321, making it easier to hold the molded body 1 in the first mold 321 when the mold is opened. In other words, it is possible to prevent mold release problems, such as the molded body 1 remaining in the second mold 341 when the mold is opened. Furthermore, because the negative pressure is applied to the cavity 33 through the gas inlet hole 326 through which pressurized gas is introduced, it is not necessary to provide any other holes, other than the gas inlet hole 326, for applying a negative pressure to the cavity 33. In other words, the configuration of the mold 31 can be simplified.

[0046] According to this embodiment, after the mold 31 is opened, pressurized gas is introduced into the cavity 33, so that the hardened molded body 1 can be easily released from the mold 31. In addition, a complex ejector mechanism composed of, for example, an ejector pin is not required. Therefore, no marks of the ejector mechanism are left on the molded body 1. Furthermore, since oil from the ejector mechanism does not get on the molded body 1, cleaning of the molded body 1 is not required.

[0047] According to this embodiment, since it is detected that the molded body 1 has been released from the mold 31, the molding of the next molded body 1 can be carried out efficiently.

[0048] According to this embodiment, if it is not detected that the molded body 1 has been released from the mold, pressurized gas is further introduced into the cavity 33, thereby increasing the possibility of releasing the hardened molded body 1 from the mold 31 even if it is not detected that the molded body 1 has been released from the mold.

[0049] According to this embodiment, a porous member 328 is disposed at a position adjacent to the cavity 33 of the gas inlet hole 326, and the pressurized gas is introduced through the porous member 328, so that the plasticized molding material 11 is not injected into the gas inlet hole 326.

[0050] According to this embodiment, the porous member 328 is produced by additive manufacturing, so that through-holes with low flow resistance during gas flow can be formed, thereby enabling efficient introduction and suction of gas into the cavity 33.

[0051] 2. Second embodiment ***Mold Overview*** In the second embodiment, the injection molding apparatus 100 is equipped with a mold 31A shown in Fig. 6, which differs from the mold 31 shown in the first embodiment. Moreover, the mold 31A is equipped with a first mold 321A shown in Fig. 6, which differs from the first mold 321 shown in the first embodiment. The first mold 321A is mainly a movable convex mold. In Fig. 6, the same components as those in the previous figures are designated by the same reference numerals, and detailed explanations thereof will be omitted.

[0052] 6, the first attachment portion 32 and the second attachment portion 34 are not shown. In addition, in order to clearly show the configuration, horizontal hatching is applied to the gas introduction hole 326 and the porous member 328 provided in the gas introduction hole 326 in Fig. 6. Furthermore, vertical hatching is applied to the gas intake hole 327, which will be described later, and the porous member 328 provided in the gas intake hole 327.

[0053] In the second embodiment, a part of the pressurized flow path 521 and a part of the intake air flow path 541 formed inside the first mold 321A are not connected to each other inside the first mold 321A, unlike the part of the pressurized flow path 521 and the part of the intake air flow path 541 in the first embodiment. That is, in the second embodiment, the part of the pressurized flow path 521 and the part of the intake air flow path 541 formed inside the first mold 321A are formed independently of each other.

[0054] The mold convex side surface 324 is a portion of the surface of the cavity 33 to which the cured molded body 1 is likely to adhere. A gas inlet hole 326 is provided in the mold convex side surface 324, extending from the mold convex side surface 324 toward the inside of the first mold 321A along the X-axis. A porous member 328, which allows gas to flow, is disposed in the gas inlet hole 326 at a position at least adjacent to the cavity 33. Pressurized gas is introduced into the cavity 33 via the porous member 328 provided in the gas inlet hole 326. The gas inlet hole 326 is connected to a pressurized gas flow path 521. This allows pressurized gas to be introduced into the cavity 33 from the gas inlet hole 326.

[0055] The mold convex tip surface 323 is a portion of the surface of the cavity 33 that is easy to suck in the cured molded body 1. The mold convex tip surface 323 is provided with a gas inlet hole 327 that extends from the mold convex tip surface 323 along the Y axis toward the inside of the first mold 321A. A porous member 328 that allows gas to flow is disposed at a position of the gas inlet hole 327 adjacent to the cavity 33. Negative pressure is applied to the cavity 33 via the porous member 328. This allows negative pressure to be applied to the cavity 33 from the gas inlet hole 327. The negative pressure is applied in the +Y direction, which is the same direction as the +Y direction in which the cured molded body 1 is released from the second mold 341, making it easy to hold the molded body 1 in the first mold 321A when the mold is opened.

[0056] As described above, in this embodiment, after the molding material 11 is injected in the material injection step of step S3, and before the mold 31 is opened in the mold clamping OFF step of step S6, a negative pressure is applied to the cavity 33 from the gas intake hole 327, which is provided in a position different from the gas introduction hole 326, in the intake ON step of step S5. This causes the molded body 1 to be sucked into the first mold 321A, making it easier to hold the molded body 1 in the first mold 321A when the mold is opened. In other words, it is possible to prevent mold release problems, such as the molded body 1 remaining in the second mold 341 when the mold is opened.

[0057] As described above, the molding method and injection molding apparatus 100 of the second embodiment can provide the same effects as those of the first embodiment. Furthermore, the molding method and injection molding apparatus 100 of this embodiment can provide the following effects.

[0058] According to this embodiment, after the molding material 11 is injected and before the mold 31A is opened, negative pressure is applied to the cavity 33 through the gas intake hole 327, which is provided at a position above the first mold 321A and is different from the gas introduction hole 326. This causes the molded body 1 to be sucked into the first mold 321A, thereby preventing mold release failure in which the molded body 1 remains in the second mold 341 during mold opening. Furthermore, since pressurized gas can be selectively introduced to the portion of the first mold 321A where the molded body 1 is likely to adhere, the molded body 1 can be easily released from the first mold 321A. In this way, a mold 31A can be configured that can selectively hold and release the molded body 1 when releasing it from the mold 31A.

[0059] According to this embodiment, a porous member 328 is placed at a position adjacent to the cavity 33 of the gas intake hole 327, and negative pressure is applied to the cavity 33 via the porous member 328, so that the plasticized molding material 11 is not injected into the gas intake hole 327.

[0060] ***Variations*** In each embodiment, the pressure of the pressurized gas is, for example, about 0.4 MPa, but it may be other than 0.4 MPa. Also, in each embodiment, the pressure of the pressurized gas in the pressurized gas introduction ON step of step S2 and the pressure of the pressurized gas in the pressurized gas introduction ON step of step S8 may be changeable. For example, by branching pressurized flow path 521 into two and providing one of the branched pressurized flow paths 521 with a regulator and providing each of the two branched pressurized flow paths 521 with a valve that is opened and closed by control unit 50, the pressure of the pressurized gas can be selectively changed.

[0061] In this case, for example, the pressure of the pressurized gas pressurized by pressurizing unit 52 can be set to about 0.8 MPa, and the pressure of the pressurized gas introduced via one pressurized flow path 521 equipped with a regulator can be set to about 0.4 MPa. As a result, in the pressurized gas introduction ON step of step S2, the pressure of the pressurized gas pressurized by pressurizing unit 52 can be reduced to about 0.4 MPa by the regulator, thereby promoting the formation of a skin layer on the surface of plasticized molding material 11. Furthermore, in the pressurized gas introduction ON step of step S8, by spraying pressurized gas pressurized to about 0.8 MPa by pressurizing unit 52 onto molded body 1, mold 31 can be more reliably released from mold 31 or mold 31A.

[0062] That is, the pressure of the pressurized gas introduced into the cavity 33 may be set higher when releasing the molded body 1 from the mold 31 or mold 31A than when injecting the plasticized molding material 11. In this way, the pressurized gas for releasing the molded body 1 from the mold 31 or mold 31A is introduced at a pressure higher than the pressure when a skin layer is formed, so that the molded body 1 after hardening can be more reliably released from the mold 31 or mold 31A.

[0063] In each embodiment, a compressor device is used as the pressurizing unit 52, and a vacuum pump device is used as the suction unit 54, but this is not limiting. A single device that functions as both a compressor and a vacuum pump may be used as the pressurizing unit 52 and the suction unit 54. This allows the injection molding apparatus 100 to have a simple configuration.

[0064] In each embodiment, resin is exemplified as molding material 11, but this is not limiting. For example, metal powder may be used as molding material 11, or a material in which metal powder and a binder are uniformly kneaded may be used. This also provides the same effects as in each embodiment.

[0065] In each embodiment, the injection molding apparatus 100 is exemplified as the molding apparatus, but the molding apparatus is not limited to this. For example, it may be a die-casting apparatus that injects molten metal into the mold 31 or mold 31A to mold the molded body 1. The die-casting apparatus is an example of a "molding apparatus." This can also achieve the same effects as in each embodiment.

[0066] In each embodiment, the first mold 321 or the first mold 321A is a movable mold, and the second mold 341 is a fixed mold, but this is not limiting. For example, by appropriately changing the configuration of the mold clamping unit 40, the first mold 321 or the first mold 321A may be a fixed mold and the second mold 341 may be a movable mold, or the first mold 321 or the first mold 321A and the second mold 341 may be movable molds. This also makes it possible to obtain the same effects as in each embodiment.

[0067] In each embodiment, an injection molding apparatus 100 has been described in which the first mounting portion 32 is provided with the first die 321 or the first die 321A, and the second mounting portion 34 is provided with the second die 341, but this is not limiting. For example, depending on the shape of the molded body 1, the second die 341 may be provided in the first mounting portion 32, and the first die 321 or the first die 321A may be provided in the second mounting portion 34. In this case, the injection hole 343 is provided in the first die 321 or the first die 321A. This also achieves the same effects as in each embodiment. [Explanation of symbols]

[0068] 1...molded body, 100...injection molding apparatus, 10...material supply section, 11...molding material, 20...injection section, 30...mold section, 31, 31A...mold, 32...first mounting section, 321, 321A...first mold, 322...mold convex section, 323...mold convex section tip surface, 324...mold convex section side, 325...gas vent, 326...gas introduction hole, 327...gas intake hole, 328...porous member, 33...cavity, 34...second mounting section, 341...second mold, 342...sprue, 343...injection hole, 40...mold clamping section, 42...mold drive section, 44...mold clamping ball screw section, 50...control section, 52...pressurizing section, 521...pressurized flow path, 531...communication path, 54...air intake section, 541...air intake flow path.

Claims

1. A molding method for molding a molded body using a mold in which a cavity is defined by clamping together a first mold and a second mold that can be opened, introducing a pressurized gas into the cavity through a gas inlet provided in the first mold; A molding method characterized by injecting a plasticized molding material into the cavity while the pressurized gas is being introduced.

2. After injecting the molding material and before opening the mold, applying a negative pressure to the cavity through the gas introduction hole; The molding method according to claim 1 .

3. After injecting the molding material and before opening the mold, a negative pressure is applied to the cavity from a gas intake hole provided in the first mold at a position different from that of the gas introduction hole; The molding method according to claim 1 .

4. After the mold is opened, the pressurized gas is introduced into the cavity. The molding method according to claim 1 .

5. Detecting that the molded body has been released from the first mold; 5. The molding method according to claim 4.

6. If it is not detected that the molded body has been released from the mold, the pressurized gas is further introduced into the cavity. The molding method according to claim 5 .

7. a porous member is disposed at a position adjacent to the cavity of the gas introduction hole, and the pressurized gas is introduced through the porous member; The molding method according to claim 1 .

8. a porous member is disposed at a position of the gas inlet hole adjacent to the cavity, and a negative pressure is applied to the cavity via the porous member; The molding method according to claim 3 .

9. The porous member is produced by additive manufacturing.

9. The molding method according to claim 7 or 8.

10. A molding apparatus comprising a mold in which a cavity is defined by first and second molds that can be opened and that are clamped together, and a control unit that controls a molding operation, the first mold has a gas inlet through which a pressurized gas is introduced, The molding apparatus is characterized in that the control unit injects plasticized molding material into the cavity while introducing the pressurized gas into the cavity through the gas inlet.

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