Injection device for foam molding, injection molding machine, and material supply method

Abstract

The invention provides an injection device for foam molding, an injection molding machine and a material supply method. In an injection device which also supplies gas as a physical foaming agent from a material supply port to prevent reverse flow of the gas, the material can be smoothly supplied. The injection device (3) is provided with a material supply device (25) and a gas supply device (23). The gas supply device is connected to a center-side gas supply port (34) in the vicinity of the center of the heating cylinder (17) and to a material-supply-side gas supply port (37) in the vicinity of the material supply port (35). The material supply device is provided with a material storage unit (41) and a pressure adjustment buffer unit (42) that stores a predetermined amount of material from the material storage unit and supplies the stored material to the material supply port side. In the pressure adjustment buffer section (42), a first valve (44) is provided on the material storage section side, and a second valve (47) is provided on the material supply port side.

Description

Technical Field

[0001] The present invention relates to an injection device for forming a foamed molded article by injecting a gas into an injection material, an injection molding machine including such an injection device, and a material supply method for supplying a material to the injection device. Background Art

[0002] An injection molding machine for forming a foamed molded article using a so-called inert gas such as nitrogen or carbon dioxide gas as a physical foaming agent is configured as follows. First, the injection device of the injection molding machine includes a heating cylinder and a screw, and the heating cylinder has a plurality of regions according to the shape of the screw. That is, there are a plasticizing zone on the upstream side where the resin is plasticized, a gas supply zone on the downstream side of the plasticizing zone where gas is supplied, and a kneading and compressing zone on the downstream side thereof where the resin and the gas are kneaded and compressed together. The resin kneaded and compressed with the gas is metered in a predetermined amount, and the metered resin is injected into the mold. Thereby, the gas foams in the mold to obtain a foamed molded article.

[0003] Patent Document 1 also shows an injection device for supplying a gas to obtain a foamed molded article. Also in this injection device, gas is supplied near the center of the heating cylinder, that is, in the gas supply zone, but gas is also supplied from other parts. Specifically, gas is also supplied from the material supply port for supplying the material to the heating cylinder. Since the injection device described in Patent Document 1 also supplies gas from the material supply port, it is possible to prevent the gas supplied from the gas supply zone from flowing back in the heating cylinder.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2023-118318 Summary of the Invention

[0007] Since the injection device described in Patent Document 1 also supplies gas from the material supply port, it is possible to prevent the backflow of gas in the heating cylinder. However, a problem to be solved has also been found. Specifically, the pressure of the gas supplied from the material supply port hinders the material from falling from the hopper. If the material does not fall smoothly, the supply of the material from the material supply port becomes unstable, which affects the quality of the obtained molded article.

[0008] In the present disclosure, in an injection device that also supplies gas from the material supply port to prevent gas backflow, an injection device is provided that can keep the pressure in the heating cylinder constant and supply the material smoothly.

[0009] Other problems and new features will become clear from the description of this specification and the appended drawings.

[0010] The present disclosure is an injection device having the following structure. That is, the injection device includes: a heating cylinder; a screw; a material supply device that supplies material to a material supply port formed in the heating cylinder; and a gas supply device that supplies a gas as a physical foaming agent to the heating cylinder. The gas supply device is connected to a central side gas supply port near the center of the heating cylinder and a material supply side gas supply port near the material supply port. The material supply device includes a pressure regulating buffer section and a material storage section that stores material. The pressure regulating buffer section retains a specified amount of material from the material storage section and supplies the retained material to the material supply port side. At the pressure regulating buffer section, a first valve is provided on the material storage section side, and a second valve is provided on the material supply port side.

[0011] Effects of the Invention

[0012] According to the present disclosure, the material can be smoothly supplied to the heating cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a front view which shows the injection molding machine of 1st Embodiment.

[0014] Figure 2 It is a front cross-sectional view showing the injection device according to the first embodiment.

[0015] Figure 3 This is a flowchart showing the material supply method according to the first embodiment.

[0016] Figure 4A It is a front cross-sectional view showing the injection device according to the first embodiment.

[0017] Figure 4B It is a front cross-sectional view showing the injection device according to the first embodiment.

[0018] Figure 4C It is a front cross-sectional view showing the injection device according to the first embodiment.

[0019] Figure 4D It is a front cross-sectional view showing the injection device according to the first embodiment.

[0020] Figure 5 It is a front cross-sectional view showing an injection device according to a modified example of the first embodiment.

[0021] Figure 6 This is a flowchart showing a material supply method according to a modified example of the first embodiment.

[0022] Figure 7 It is a front cross-sectional view showing an injection device according to a second embodiment.

[0023] Figure 8 This is a flowchart showing the material supply method according to the second embodiment.

[0024] Description of Reference Numerals

[0025] 1: Injection molding machine, 2: Mold clamping device, 3: Injection device, 4: Control device, 7: Fixed plate, 8: Movable plate, 9: Mold clamping housing, 10: Tie rod, 11: Toggle mechanism, 13: Fixed side mold, 14: Movable side mold, 17: Heating cylinder, 18: Screw, 20: Screw drive device, 21: Injection nozzle, 23: Gas supply device, 25: Material supply device, 27: Gas cylinder, 28: 1st piping, 30: 1st pressure reducing valve, 31: 2nd piping, 32: 2nd pressure reducing valve, 34: Center side gas supply port, 35: Material supply port, 37: Material supply side gas supply port, 3 8: Pressure gauge, 39: Pressure gauge, 41: Hopper, 42: Pressure regulating container, 44: Inlet valve, 45: Actuator, 47: Outlet valve, 48: Actuator, 49: Sealing member, 51: Gas supply port on the buffer side, 52: Pipe, 53: Gas supply valve, 54: Exhaust section, 55: Release valve, 56: Exhaust pipe, 60: Material tank, 61: Pressure regulating hopper, 62: Quantitative feeder, 64: Receiving valve, 65: Actuator, 67: Discharge valve, 68: Actuator, 70: Upper limit sensor, 71: Lower limit sensor, 75: Gasket, 77: Material delivery screw, 78: Motor DETAILED DESCRIPTION

[0026] Hereinafter, specific embodiments will be described in detail with reference to the accompanying drawings. However, the embodiments are not limited to the following embodiments. In order to make the description clear, the following description and drawings are appropriately simplified. In each of the drawings, the same element is marked with the same figure mark, and repeated descriptions are omitted as needed. In addition, in order to avoid the drawings becoming complicated, there are parts where hatching is omitted.

[0027] [First embodiment]

[0028] <Injection molding machine>

[0029] like Figure 1 As shown, the injection molding machine 1 of the first embodiment includes a mold clamping device 2 and an injection device 3 which are provided on a base B, and is controlled by a control device 4 which is a control unit.

[0030] <Mold clamping device>

[0031] The mold clamping device 2 can be composed of a direct pressure type mold clamping device, but in the present embodiment, it is composed of a toggle type mold clamping device. The mold clamping device 2 includes a fixed plate 7 fixed to a base B, a movable plate 8 slidably provided on the base B, and a mold clamping housing 9 slidably provided on the base B. The fixed plate 7 and the mold clamping housing 9 are connected by a plurality of tie rods 10, 10, ..., the movable plate 8 is arranged between the fixed plate 7 and the mold clamping housing 9, and a toggle mechanism 11 is provided between the movable plate 8 and the mold clamping housing 9. A fixed side mold 13 and a movable side mold 14 are provided on the fixed plate 7 and the movable plate 8 of such a mold clamping device 2, respectively. If the toggle mechanism 11 is driven, the molds 13 and 14 are clamped. Or the molds 13 and 14 are opened and closed.

[0032] <Injection device>

[0033] The injection device 3 includes a heating cylinder 17, a screw 18 placed in the heating cylinder 17, a screw driving device 20 that supports the heating cylinder 17 and drives the screw 18, and an injection nozzle 21 provided at the front end of the heating cylinder 17. The injection device 3 of the first embodiment further includes a gas supply device 23 that supplies a gas as a physical foaming agent and a material supply device 25 that supplies a material, namely, resin pellets, to the heating cylinder 17.

[0034] <Gas supply device>

[0035] exist Figure 2 The injection device 3 is shown enlarged in FIG. The gas supply device 23 of the first embodiment is described. The gas supply device 23 includes a gas cylinder 27, a first pressure reducing valve 30 provided on a first pipe 28 branching from the gas cylinder 27, and a second pressure reducing valve 32 provided on a second pipe 31 also branching from the gas cylinder 27. A gas such as nitrogen gas and carbon dioxide gas as a physical foaming agent is stored in the gas cylinder 27. The first pipe 28 is connected to a central side gas supply port 34 provided near the center of the heating cylinder 17, and the second pipe 31 is connected to a material supply side gas supply port 37 provided near a material supply port 35 of the heating cylinder 17. Pressure gauges 38 and 39 are provided on each of the pipes 28 and 31. It should be noted that the material supply side gas supply port 37 may also be provided in the heating cylinder 17 as long as it is provided near the material supply port 35.

[0036] In the first embodiment, the pressure of the gas supplied to the material supply side gas supply port 37 is reduced so as to be lower than the pressure of the gas supplied to the central side gas supply port 34. This is because the gas supplied to the central side gas supply port 34 is at a relatively high pressure because it needs to be efficiently supplied to the resin kneaded in the injection device 3. In contrast, the gas supplied to the material supply side gas supply port 37 can be at a relatively low pressure as long as the backflow of the gas in the heating cylinder 17 can be prevented. In addition, as described later, a part of the gas supplied to the material supply side gas supply port 37 will be discharged to the atmosphere, so there is also an advantage of being able to reduce the discharge amount under low pressure.

[0037] In addition, the pressure of the gas supplied to the central gas supply port 34 and the material supply side gas supply port 37 may be equal. In this case, the amount of gas discharged to the atmosphere is slightly increased, but the overall device can be simplified. That is, the first pipe 28 and the second pipe 31 can be provided as one, and the pressure reducing valves 30, 32 and the pressure gauges 38, 39 can be reduced by one each.

[0038] <Material supply device>

[0039] like Figure 2 As shown, the material supply device 25 of the first embodiment includes a material storage portion, i.e., a hopper 41, in which a material is placed, and a pressure regulating buffer portion, i.e., a pressure regulating container 42, which regulates the internal pressure. The upper portion of the pressure regulating container 42 is connected to the lower portion of the hopper 41, and the lower portion of the pressure regulating container 42 is connected to the material supply port 35 of the heating cylinder 17. The pressure regulating container 42 is provided with a first valve, i.e., an inlet valve 44, between the pressure regulating container 42 and the hopper 41. When the inlet valve 44 is opened by an actuator 45, the material in the hopper 41 enters the pressure regulating container 42. In addition, the pressure regulating container 42 is provided with a second valve, i.e., an outlet valve 47, between the pressure regulating container 42 and the material supply port 35. When the outlet valve 47 is opened by an actuator 48, the material in the pressure regulating container 42 is supplied to or discharged from the material supply port 35.

[0040] In the first embodiment, the material of the amount of material temporarily stored in the pressure regulating container 42 is more than the amount of one molding cycle. In other words, the amount of material stored in the pressure regulating container 42 is more than the amount of one metering process performed in the injection device 3. Therefore, as described later, in the metering process, the inlet valve 44 and the outlet valve 47 only need to be opened and closed once. However, the material temporarily stored in the pressure regulating container 42 can also be reduced. However, in this case, the inlet valve 44 and the outlet valve 47 need to be opened and closed multiple times in one metering process.

[0041] In the material supply device 25, predetermined sealing members 49, 49 such as O-rings are provided at the connection portion between the material supply port 35 and the pressure regulating container 42. Thus, the airtightness of the pressure regulating container 42 and the material supply port 35 is maintained. In addition, when the first valve and the second valve, that is, the inlet valve 44 and the outlet valve 47, are both closed, the airtightness in the pressure regulating container 42 is maintained.

[0042] <Material supply method>

[0043] The material supply method of the first embodiment implemented in the injection device 3 of the first embodiment will be described. The material supply method is implemented in the control device 4 (see Figure 1 ) is implemented. From the first valve, that is, the inlet valve 44 (refer to Figure 2 ) is closed. Figure 3 Step S01 shown in FIG. Figure 4A As shown, the actuator 48 is driven to close the second valve, namely the outlet valve 47. As a result, the material supply port 35 of the heating cylinder 17 and the pressure regulating container 42 are cut off. In this state, the pressure of the gas in the material supply port 35 and the pressure regulating container 42 are equal. In other words, the gas enters the pressure regulating container 42 at a predetermined pressure.

[0044] Next, the control device 4 (see Figure 1 )Implementation Figure 3 In other words, Figure 4B As shown, the actuator 45 is driven to open the first valve, i.e., the inlet valve 44. Thus, the hopper 41 is connected to the pressure regulating container 42. The inside of the hopper 41 is at atmospheric pressure, and the gas in the pressure regulating container 42 is instantly discharged to the side of the hopper 41. Thus, the inside of the pressure regulating container 42 also becomes atmospheric pressure. Since the pressures in the pressure regulating container 42 and the hopper 41 are equal, the material in the hopper 41 falls smoothly into the pressure regulating container 42. Thus, a specified amount of material is temporarily stored in the pressure regulating container 42. In addition, since the gas in the pressure regulating container 42 is discharged to the side of the hopper 41 in step S02, the gas is discharged from the hopper 41 to the outside and is discarded.

[0045] Next, the control device 4 (see Figure 1 )Implementation Figure 3 Step S03 shown in FIG. Figure 4C As shown, the first valve, that is, the inlet valve 44, is closed. As a result, the pressure regulating container 42 is cut off from the hopper 41. At this time, the pressure regulating container 42 is in the state of atmospheric pressure. The control device 4 is as shown in FIG. Figure 3 In step S04, it is determined whether the metering process has started in the injection device 3. If the metering process has not started (No), step S04 is repeated. On the other hand, if the metering process has started (Yes), the process moves to step S05.

[0046] In step S05, Figure 4D As shown, the second valve, namely the outlet valve 47, is opened. As a result, the gas instantly flows from the material supply port 35 to the pressure regulating container 42, and the pressure becomes equal. If the pressure is equal, the material stored in the pressure regulating container 42 smoothly falls to the material supply port 35. The control device 4 (refer to Figure 1 ) The metering process is carried out in the injection device 3.

[0047] Control device 4 implementation Figure 3 In step S06, it is determined whether the metering process has been completed. If it has not been completed (no), step S06 is repeated. On the other hand, if it has been completed (yes), the process returns to step S01. The above steps are repeated in the same manner. Steps S01 and S02 are used to feed the material to the material supply port 35 (refer to Figure 2 ) is a preparation process for supply, so it can be called a supply preparation process. In contrast, steps S03 to S06 can be called a supply process because the material is actually supplied to the material supply port 35.

[0048] <Modification of the first embodiment>

[0049] The first embodiment can be modified in various ways. Figure 5 An injection device 3' of a modified example is shown in the figure. The same reference numerals are given to the same components as those in the first embodiment and the description thereof is omitted. In the injection device 3' of the modified example of the first embodiment, the gas supply device 23' and the material supply device 25' are modified. First, a buffer-side gas supply portion 51 to which gas is supplied is provided in the pressure regulating container 42' of the material supply device 25'. The second piping 31 of the gas supply device 23' is branched, and the branched piping 52 is provided with a gas supply valve 53 and is connected to the buffer-side gas supply portion 51. In addition, an exhaust portion 54 is provided in the pressure regulating container 42', and an exhaust pipe 56 provided with a release valve 55 is connected to the exhaust portion 54.

[0050] <Modification of material supply method>

[0051] For a material supply method of a modified example implemented in the injection device 3 ′ of the modified example of the first embodiment, refer to Figure 6 Several steps (steps S01, S02, ...) of the material supply method of the modified example and Figure 3 The material supply method is the same as that of the first embodiment shown, so the same steps will be described in a simplified manner, and the modified steps will be described in detail.

[0052] The material supply method of the modified example is also described from the state where the first valve, namely the inlet valve 44, is closed. Figure 6 As shown, step S01 is implemented, using the control device 4 (refer to Figure 1 ) Close the second valve, namely the outlet valve 47. The control device 4 (refer to Figure 1 ) Open the discharge valve 55 in step S11 (refer to Figure 5 ). Thus, the gas is discharged from the pressure regulating container 42' and the interior becomes atmospheric pressure. Next, if the control device 4 opens the inlet valve 44 in step S02, the material in the hopper 41 falls smoothly into the pressure regulating container 42' because there is no pressure difference.

[0053] Control device 4 (refer to Figure 1 ) through step S03 (refer to Figure 6 ) Close the inlet valve 44 (refer to Figure 5 ). Next, step S12 is implemented to close the release valve 55. As a result, the pressure regulating container 42' becomes sealed. The control device 4 executes step S13. That is, the gas supply valve 53 is opened. As a result, gas is supplied to the pressure regulating container 42' and the internal pressure becomes equal to that of the material supply port 35. Step S04 is used to determine whether the metering process has started. If it has started (yes), the outlet valve 47 is opened through step S05. As a result, since there is no pressure difference between the pressure regulating container 42' and the material supply port 35, the material in the pressure regulating container 42' falls smoothly and is supplied to the material supply port 35. If it is determined that the metering process has been completed (yes) through step S06, step S14 is implemented. That is, the gas supply valve 53 is closed. Return to step S01.

[0054] [Second embodiment]

[0055] The second embodiment is described below. The injection molding machine of the second embodiment has Figure 7 In addition to the injection device 3A shown, the mold clamping device and the like are similar to the injection molding machine 1 of the first embodiment (see Figure 1 ) is similarly configured. The description of the same structure is omitted. In the injection device 3A of the second embodiment, the injection device 3 (see Figure 2 ) or an injection device 3' of a modified example of the first embodiment (see Figure 5 ) The same structure is marked with the same figure mark and the description is omitted.

[0056] Regarding the injection device 3A of the second embodiment, the material supply device 25A is different from that of the first embodiment. The material supply device 25A includes: a material storage part, i.e., a material tank 60, which contains a relatively large amount of material; a pressure regulating buffer part, i.e., a pressure regulating hopper 61, which is a relatively large-capacity pressure regulating buffer; and a quantitative feeder 62 that supplies material with high precision.

[0057] A first valve, namely a receiving valve 64, is provided between the material tank 60 and the pressure regulating hopper 61, and the receiving valve 64 is opened and closed by an actuator 65. A second valve, namely a discharge valve 67, is provided between the pressure regulating hopper 61 and the quantitative feeder 62, and the discharge valve 67 is opened and closed by an actuator 68. When the discharge valve 67 is opened, the material stored in the pressure regulating hopper 61 is supplied to or discharged from the quantitative feeder 62. In this embodiment, the pressure regulating hopper 61 stores the material in an amount sufficient for multiple molding cycles.

[0058] The pressure regulating hopper 61 is provided with a buffer-side gas supply unit 51, and a pipe 52 branched from the second pipe 31 of the gas supply device 23A supplies gas to the buffer-side gas supply unit 51 via a gas supply valve 53. In addition, the pressure regulating hopper 61 is provided with an exhaust pipe 56, and the exhaust pipe 56 is provided with a discharge valve 55 and a suction pump 57. As can be clearly seen from the material supply method described later, the pressure regulating hopper 61, the receiving valve 64 and the discharge valve 67 in the second embodiment are respectively the same as the pressure regulating container 42' in the modified example of the first embodiment (see Figure 5 ), the inlet valve 44 and the outlet valve 47 are similar. In other words, they play the same role. The pressure regulating hopper 61 is provided with an upper limit sensor 70 for detecting that the material stored inside has reached the upper limit, and a lower limit sensor 71 for detecting that the material stored inside has reached the lower limit.

[0059] The quantitative feeder 62 is connected to the material supply port 35 via a gasket 75, and is provided with a material delivery screw 77 for delivering the material. The material delivery screw 77 is rotated by a motor 78. The quantitative feeder 62 has a predetermined capacity, and a material larger than the amount of one molding cycle is placed therein.

[0060] In the second embodiment, the material supply side gas supply port 37 is provided between the pressure regulating hopper 61 and the quantitative feeder 62. Since the gas is supplied from this position, the pressure of the gas is uniform from the quantitative feeder 62 to the material supply port 35.

[0061] <Material supply method>

[0062] In the injection device 3A of the second embodiment, the material is supplied to the material supply port 35 of the heating cylinder 17 by the quantitative feeder 62. The quantitative feeder 62 is controlled by the control device 4 (see Figure 1) and is driven. On the other hand, the supply or discharge of material from the pressure regulating hopper 61 to the quantitative feeder 62 does not need to be synchronized with the molding cycle, and is supplied in an asynchronous manner. The material supply method to the quantitative feeder 62 is described as the material supply method of the second embodiment. In addition, as described above, the quantitative feeder 62 is loaded with more than the amount of material for one molding cycle, so even if the supply of material from the pressure regulating hopper 61 to the quantitative feeder 62 is asynchronous with the molding cycle, no problem will occur.

[0063] When describing the material supply method of the second embodiment, it is assumed that the first valve, namely the receiving valve 64, is closed and the second valve, namely the discharge valve 67, is opened. Furthermore, it is assumed that the gas is supplied from the buffer side gas supply unit 51 to the pressure regulating hopper 61. In this state, the material in the pressure regulating hopper 61 is freely supplied or discharged to the material supply port 35 side, namely the quantitative feeder 62 side.

[0064] In the material supply method of the second embodiment, first, Figure 8 As shown, the control device 4 (refer to Figure 1 ) implements step S21. That is, the lower limit sensor 71 detects the pressure in the pressure regulating hopper 61 (refer to Figure 7 ) is reduced. If there is still material (No), repeat step S21. On the other hand, if the material reaches the lower limit (Yes), transfer to step S22. The control device 4 closes the gas supply valve 53 through step S22. As a result, the supply of gas to the pressure regulating hopper 61 is stopped. Next, step S23 is implemented to close the second valve, that is, the discharge valve 67. As a result, the supply of material from the pressure regulating hopper 61 to the quantitative feeder 62 is stopped. The control device 4 opens the discharge valve 55 through step S24. As a result, the gas in the pressure regulating hopper 61 is discharged, and the inside becomes atmospheric pressure.

[0065] Control device 4 (refer to Figure 1 )Execute step S25. Open the first valve, i.e., the receiving valve 64. Then, drive the suction pump 57. Thus, the material is sucked from the material tank 60 and supplied to the pressure regulating hopper 61. Air enters the pressure regulating hopper 61 together with the material, but the air is discharged to the outside through the relief valve 55 and the suction pump 57. In other words, only the material is stored in the pressure regulating hopper 61. The control device 4 implements step S26, and uses the upper limit sensor 70 to determine whether the stored material has reached the upper limit. If the upper limit has not been reached (No), repeat step S26. On the other hand, if the upper limit has been reached (Yes), transfer to step S27.

[0066] Control device 4 (refer to Figure 1) implements step S27 and closes the receiving valve 64. In addition, the suction pump 57 is stopped. As a result, the supply of material from the material tank 60 is stopped. Next, the control device 4 implements step S28 and closes the discharge valve 55. As a result, the pressure regulating hopper 61 becomes sealed. The control device 4 opens the gas supply valve 53 through step S29. Gas is supplied to the pressure regulating hopper 61, and the pressure of the gas becomes equal to that of the material supply port 35. The control device 4 implements step S30 and opens the second valve, namely the discharge valve 67. That is, the material is supplied from the pressure regulating hopper 61 to the quantitative feeder 62 again. Return to step S21.

[0067] The invention completed by the inventors of the present application is specifically described above based on the embodiments, but the present invention is not limited to the described embodiments, and various changes can be made without departing from the scope of the invention. The multiple examples described above can also be combined appropriately and implemented.

Claims

1. An injection device, characterized in that: include: Heating cylinder; A screw disposed in the heating cylinder; a material supply device for supplying material to a material supply port formed in the heating cylinder; and a gas supply device for supplying a gas serving as a physical foaming agent to the heating cylinder, The gas supply device is connected to a central gas supply port provided near the center of the heating cylinder and a material supply side gas supply port provided near the material supply port. The material supply device includes a pressure adjustment buffer unit and a material storage unit for storing the material. The pressure regulating buffer portion stores a predetermined amount of material from the material storage portion and supplies the stored material to the material supply port side. The pressure regulating buffer portion is provided with a first valve on the material storage portion side, and is provided with a second valve on the material supply port side.

2. The injection device according to claim 1, characterized in that The injection device is provided with a control device, The control device is configured to be capable of executing a supply preparation process and a supply process, In the supply preparation process, the second valve is closed, and then the first valve is opened to store the material from the material storage unit in the pressure regulating buffer unit. In the supply process, the first valve is closed, and then the second valve is opened to supply the material stored in the pressure regulating buffer portion to the material supply port side.

3. The injection device according to claim 1 or 2, characterized in that: The pressure regulating buffer portion and the material supply port are connected to each other via a predetermined sealing member so as to maintain airtightness.

4. The injection device according to claim 1 or 2, characterized in that: The pressure adjusting buffer portion stores a material in an amount equal to or greater than that of one molding cycle.

5. The injection device according to claim 1 or 2, characterized in that: The pressure adjustment buffer portion is provided with a sensor that detects whether the material in the pressure adjustment buffer portion has reached a lower limit.

6. The injection device according to claim 1 or 2, characterized in that: The pressure regulating buffer portion is provided with a relief valve for releasing the internal pressure to the atmospheric pressure.

7. The injection device according to claim 1 or 2, characterized in that: The pressure regulating buffer section is provided with a buffer section side gas supply section, The gas supply device is connected to the buffer portion side gas supply portion via a gas supply valve.

8. The injection device according to claim 1 or 2, characterized in that: The pressure of the gas supplied from the material supply side gas supply port is adjusted to be lower than the pressure of the gas supplied from the center side gas supply port.

9. The injection device according to claim 1 or 2, characterized in that: The material storage portion includes a hopper.

10. The injection device according to claim 1 or 2, characterized in that: The material supply device includes a quantitative feeder provided between the pressure regulating buffer portion and the material supply port.

11. The injection device according to claim 10, characterized in that The quantitative feeder has a capacity for feeding a material having an amount greater than that of one molding cycle.

12. An injection molding machine, characterized in that: include: An injection device for injecting resin; and A mold clamping device for closing the mold. The injection device comprises: Heating cylinder; A screw disposed in the heating cylinder; A material supply device for supplying material to a material supply port formed in the heating cylinder; and a gas supply device for supplying a gas serving as a physical foaming agent to the heating cylinder, The gas supply device is connected to a central gas supply port provided near the center of the heating cylinder and a material supply side gas supply port provided near the material supply port. The material supply device includes a pressure adjustment buffer unit and a material storage unit for storing the material. The pressure regulating buffer portion stores a predetermined amount of material from the material storage portion and supplies the stored material to the material supply port side. The pressure regulating buffer portion is provided with a first valve on the material storage portion side, and is provided with a second valve on the material supply port side.

13. The injection molding machine according to claim 12, characterized in that The injection molding machine is provided with a control device, The control device is configured to be capable of executing a supply preparation process and a supply process, In the supply preparation process, the second valve is closed, and then the first valve is opened to temporarily store the material from the material storage unit in the pressure regulating buffer unit. In the supply process, the first valve is closed, and then the second valve is opened to supply the material stored in the pressure regulating buffer portion to the material supply port side.

14. The injection molding machine according to claim 12 or 13, characterized in that: The pressure regulating buffer portion and the material supply port are connected to each other via a predetermined sealing member so as to maintain airtightness.

15. A material supply method, characterized in that: The material supply method is implemented in foam molding based on an injection device. The injection device comprises: Heating cylinder; A screw disposed in the heating cylinder; A material supply device for supplying material to a material supply port formed in the heating cylinder; and a gas supply device for supplying a gas serving as a physical foaming agent to the heating cylinder, The gas supply device is connected to a central gas supply port provided near the center of the heating cylinder and a material supply side gas supply port provided near the material supply port. The material supply device includes a material storage unit for storing the material and a pressure adjustment buffer unit for temporarily storing a predetermined amount of the material. In the pressure regulating buffer section, a first valve is provided on the material storage section side, and a second valve is provided on the material supply port side. The material supply method includes a supply preparation process and a supply process. In the supply preparation step, the second valve is closed, and then the first valve is opened to allow the material from the material storage section to enter the pressure regulating buffer section and be stored therein. In the supply step, the first valve is closed, and then the second valve is opened to supply the material stored in the pressure regulating buffer portion to the material supply port side.

16. The material supply method according to claim 15, characterized in that: The pressure adjustment buffer section is provided with a sensor, which detects whether the material in the pressure adjustment buffer section has reached a lower limit. When the sensor detects the lower limit of the material, the supply preparation step is implemented.

17. The material supply method according to claim 15, characterized in that: The supply step is performed in a metering step in a molding cycle performed in the injection device, and the supply preparation step is performed in a step other than the metering step.

18. The material supply method according to claim 15 or 16, characterized in that: The amount of material temporarily stored in the pressure regulating buffer portion is equal to or greater than the amount of one molding cycle.

19. The material supply method according to claim 15 or 16, characterized in that: The pressure regulating buffer section is provided with a relief valve for releasing the internal pressure to the atmospheric pressure. In the supply preparation step, after closing the second valve, the drain valve is opened, and then the first valve is opened.

20. The material supply method according to claim 15 or 16, characterized in that: The pressure regulating buffer section is provided with a buffer section side gas supply section, and the buffer section side gas supply section is connected to the gas supply device via a gas supply valve. In the supply step, after closing the first valve, the gas supply valve is opened, and then the second valve is opened.

21. The material supply method according to claim 20, characterized in that: In the injection device, the pressure of the gas supplied from the material supply side gas supply port is adjusted to be lower than the pressure of the gas supplied from the center side gas supply port. The pressure of the gas supplied to the buffer-side gas supply portion by opening the gas supply valve is controlled to be equal to the pressure of the gas supplied from the material-supply-side gas supply port.

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