Foam-molding injection device, injection molding machine, and material-feeding method

Abstract

To provide an injection device for preventing gas from reversely flowing by feeding gas as a physical foaming agent even from a material feed port and capable of smoothly feeding a material.SOLUTION: An injection device (3) is provided with a material-feeding device (25) and a gas-feeding device (23). The gas-feeding device (23) is connected to a center side gas-feeding port (34) near a center of a heating cylinder (17), and a material-feeding side gas-feeding port (37) near a material-feeding port (35). The material-feeding device (25) is constituted from a material storage part (41) and a pressure-adjusting buffer part (42), and the pressure-adjusting buffer part (42) makes it possible to feed a remaining material onto the material-feeding port (35) side while having come to store a predetermined amount of material from the material storage part (41). The pressure-adjusting buffer part (42) is provided with a first valve (44) on the material storage part (41) side, and with a second valve (47) on the material-feeding port (35) side.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an injection device for injecting gas into an injection material to form a foamed molded product, an injection molding machine equipped with such an injection device, and a material supply method for supplying material to the injection device.

Background Art

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

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0004] Patent Document 1 also shows an injection device in which gas is supplied to obtain a foamed molded product. In this injection device as well, gas is supplied in the vicinity of the center of the heating cylinder, that is, in the gas supply zone, but gas is also supplied from other locations. Specifically, gas is also supplied from the material supply port for supplying material to the heating cylinder. Since gas is supplied from the material supply port in the injection device described in Patent Document 1, it is possible to prevent the gas supplied from the gas supply zone from flowing backward in the heating cylinder.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the injection device described in Patent Document 1, since gas is also supplied from the material supply port, backflow of gas in the heating cylinder can be prevented. However, problems to be solved can also be found. Specifically, the pressure of the gas supplied from the material supply port hinders the fall of the material 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 product.

[0006] In the present disclosure, there is provided an injection device that supplies gas from the material supply port to prevent backflow of gas, and that can smoothly supply the material while maintaining a constant pressure in the heating cylinder.

[0007] Other problems and novel features will become apparent from the description of this specification and the accompanying drawings.

Means for Solving the Problems

[0008] The present disclosure provides an injection device having the following configuration. 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, which is 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 material storage unit that stores the material and a pressure adjustment buffer unit. The pressure adjustment buffer unit is configured to store a predetermined amount of the material from the material storage unit and supply the stored material to the material supply port side. A first valve is provided on the material storage unit side and a second valve is provided on the material supply port side in the pressure adjustment buffer unit.

Effects of the Invention

[0009] According to the present disclosure, the material can be smoothly supplied to the heating cylinder.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0011] Hereinafter, specific embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. For clarity of explanation, the following description and drawings are appropriately simplified. In each drawing, the same elements are denoted by the same reference numerals, and redundant explanations are omitted as necessary. Also, there are parts where hatching is omitted so that the drawings do not become complicated.

[0012] [First Embodiment] <Injection Molding Machine> As shown in Fig. 1, the injection molding machine 1 according to the first embodiment is roughly composed of a mold clamping device 2 and an injection device 3 provided on a bed B, and is controlled by a control means, that is, a control device 4.

[0013] <Mold clamping device> The mold clamping device 2 can be configured as a direct pressure type, but in this embodiment, it is configured as a toggle type. The mold clamping device 2 includes a fixed platen 7 fixed to the bed B, a movable platen 8 slidably provided on the bed B, and a mold clamping housing 9 also slidably provided on the bed B. The fixed platen 7 and the mold clamping housing 9 are connected by a plurality of tie bars 10, 10,.... The movable platen 8 is disposed between the fixed platen 7 and the mold clamping housing 9, and a toggle mechanism 11 is provided between the movable platen 8 and the mold clamping housing 9. A fixed mold 13 and a movable mold 14 are provided on the fixed platen 7 and the movable platen 8 of such a mold clamping device 2, respectively. When the toggle mechanism 11 is driven, the molds 13, 14 are clamped. Or the mold is opened and closed.

[0014] <Injection device> 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 tip of the heating cylinder 17. The injection device 3 according to the first embodiment further includes a gas supply device 23 that supplies a gas, which is a physical foaming agent, and a material supply device 25 that supplies a material, that is, resin pellets, to the heating cylinder 17.

[0015] <Gas supply device> Figure 2 shows the injection device 3 enlarged. The gas supply device 23 according to the first embodiment will be described. The gas supply device 23 includes a cylinder 27, a first pressure reducing valve 30 provided in a first pipe 28 branched from the cylinder 27, and a second pressure reducing valve 32 provided in a second pipe 31 branched in the same manner. The cylinder 27 is filled with a gas such as nitrogen gas or carbon dioxide gas, which is a physical foaming agent. The first pipe 28 is connected to a central 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 the material supply port 35 of the heating cylinder 17. Pressure gauges 38 and 39 are provided in the respective pipes 28 and 31. Note that the material supply side gas supply port 37 may be provided in the heating cylinder 17 as long as it is near the material supply port 35.

[0016] 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. Since the gas supplied to the central side gas supply port 34 needs to be efficiently supplied to the resin kneaded in the injection device 3, it is set to a relatively high pressure. On the other hand, the gas supplied to the material supply side gas supply port 37 only needs to prevent the backflow of the gas in the heating cylinder 17, and thus can be at a relatively low pressure. Further, as will be described later, since a part of the gas supplied to the material supply side gas supply port 37 is discharged to the atmosphere, there is also an advantage that the discharge amount can be reduced by setting the pressure to a low value.

[0017] Note that the pressures of the gases supplied to the central side gas supply port 34 and the material supply side gas supply port 37 may be made equal. In this case, the amount of gas discharged to the atmosphere will be slightly increased, but the entire device can be simplified. That is, the first and second pipes 28 and 31 can be combined into one, and the pressure reducing valves 30 and 32 and the pressure gauges 38 and 39 can be reduced to one each.

[0018] <Material supply device> As shown in Fig. 2, the material supply device 25 according to the first embodiment includes a material storage section (i.e., hopper 41) containing the material, and a pressure adjustment buffer section (i.e., pressure adjustment container 42) for adjusting the internal pressure. The upper part of the pressure adjustment container 42 is connected below the hopper 41, and the lower part is connected to the material supply port 35 of the heating cylinder 17. A first valve (i.e., inlet valve 44) is provided between the pressure adjustment container 42 and the hopper 41. When the inlet valve 44 is opened by the actuator 45, the material in the hopper 41 can be put into the pressure adjustment container 42. Further, a second valve (i.e., outlet valve 47) is provided between the pressure adjustment container 42 and the material supply port 35. When the outlet valve 47 is opened by the actuator 48, the material in the pressure adjustment container 42 can be supplied to or discharged from the material supply port 35.

[0019] In the first embodiment, the pressure adjustment container 42 is adapted to temporarily store the material for at least one molding cycle, that is, for at least one metering process performed in the injection device 3. Therefore, as will be described later, in the metering process, it is sufficient to open and close the inlet valve 44 and the outlet valve 47 once each. However, the amount of material temporarily stored in the pressure adjustment container 42 may be reduced. In that case, however, it is necessary to open and close the inlet valve 44 and the outlet valve 47 a plurality of times respectively in one metering process.

[0020] In the material supply device 25, predetermined seal members 49, 49 such as O-rings are provided at the connection portion between the material supply port 35 and the pressure adjustment container 42. Thereby, the airtightness between the pressure adjustment container 42 and the material supply port 35 is maintained. Note that the first and second valves, i.e., the inlet valve 44 and the outlet valve 47, are adapted to maintain the airtightness inside the pressure adjustment container 42 when both are closed.

[0021] <Material supply method> In the injection device 3 according to the first embodiment, a material supply method according to the first embodiment will be described. This material supply method is implemented in the control device 4 (see FIG. 1). First, an explanation will be given starting from the state where the first valve, that is, the inlet valve 44 (see FIG. 2) is closed. The control device 4 performs step S01 shown in FIG. 3. That is, as shown in FIG. 4A, the actuator 48 is driven to close the second valve, that is, the outlet valve 47. Then, the material supply port 35 of the heating cylinder 17 and the pressure adjustment container 42 are blocked. In this state, the gas pressures of the material supply port 35 and the pressure adjustment container 42 are equal. That is, the gas is contained in the pressure adjustment container 42 at a predetermined pressure.

[0022] Next, the control device 4 (see FIG. 1) performs step S02 shown in FIG. 3. That is, as shown in FIG. 4B, the actuator 45 is driven to open the first valve, that is, the inlet valve 44. Then, the hopper 41 and the pressure adjustment container 42 communicate with each other. The inside of the hopper 41 is at atmospheric pressure, and the gas in the pressure adjustment container 42 instantaneously escapes to the hopper 41 side. As a result, the inside of the pressure adjustment container 42 also becomes atmospheric pressure. Since the pressures in the pressure adjustment container 42 and the hopper 41 are equal, the material in the hopper 41 smoothly drops into the pressure adjustment container 42. As a result, a predetermined amount of material is temporarily stored in the pressure adjustment container 42. In step S02, since the gas in the pressure adjustment container 42 escapes to the hopper 41 side, the gas is discharged from the hopper 41 to the outside and will be discarded.

[0023] Next, the control device 4 (see FIG. 1) performs step S03 shown in FIG. 3. That is, as shown in FIG. 4C, the first valve, that is, the inlet valve 44 is closed. Thereby, the pressure adjustment container 42 is blocked from the hopper 41. At this time, the inside of the pressure adjustment container 42 is in an atmospheric pressure state. The control device 4 performs step S04 as shown in FIG. 3 to determine whether or not 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 proceeds to step S05.

[0024] In step S05, as shown in FIG. 4D, the second valve, that is, the outlet valve 47, is opened. Then, gas instantaneously flows from the material supply port 35 into the pressure adjustment container 42, and the pressures become equal. When the pressures become equal, the material stored in the pressure adjustment container 42 smoothly drops to the material supply port 35. The control device 4 (see FIG. 1) performs a metering process in the injection device 3.

[0025] The control device 4 performs step S06 shown in FIG. 3 to determine whether the metering process is completed. If not (NO), step S06 is repeated. On the other hand, if it is completed (YES), the process returns to step S01. Hereinafter, the same is repeated. Since steps S01 and S02 are preparation steps for supplying the material to the material supply port 35 (see FIG. 2), they can be referred to as supply preparation steps. In contrast, steps S03 to S06 can be referred to as supply steps because the material is actually supplied to the material supply port 35.

[0026] <Modification of the First Embodiment> The first embodiment can be variously modified, and FIG. 5 shows an injection device 3' according to a modification. The same members as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted. In the injection device 3' according to the modification of the first embodiment, the gas supply device 23' and the material supply device 25' are modified. First, in the pressure adjustment container 42' of the material supply device 25', a buffer part side gas supply part 51 to which gas is supplied is provided. The second pipe 31 of the gas supply device 23' is branched, and a branched pipe 52 is provided with a gas supply valve 53 and is connected to the buffer part side gas supply part 51. Further, an exhaust part 54 is provided in the pressure adjustment container 42', and an exhaust pipe 56 provided with a relief valve 55 is connected to the exhaust part 54.

[0027] <Modification of the Material Supply Method> Regarding the material supply method according to the modification of the first embodiment, which is implemented in the injection device 3‘, it will be described with reference to FIG. 6. The material supply method according to the modification has some steps (steps S01, S02, …) similar to the material supply method according to the first embodiment shown in FIG. 3. Therefore, the description of the similar steps will be simplified, and the modified steps will be described in detail.

[0028] Also in the material supply method according to the modification, the description starts from the state where the first valve, that is, the inlet valve 44, is closed. First, as shown in FIG. 6, step S01 is implemented, and the second valve, that is, the outlet valve 47, is closed by the control device 4 (see FIG. 1). The control device 4 (see FIG. 1) opens the relief valve 55 (see FIG. 5) in step S11. Then, gas is discharged from the pressure adjustment container 42‘ and the inside becomes atmospheric pressure. Subsequently, when the control device 4 opens the inlet valve 44 in step S02, since there is no pressure difference, the material in the hopper 41 smoothly drops into the pressure adjustment container 42’.

[0029] The control device 4 (see FIG. 1) closes the inlet valve 44 (see FIG. 5) in step S03 (see FIG. 6). Then, step S12 is implemented to close the relief valve 55. Then, the pressure adjustment container 42‘ becomes airtight. The control device 4 executes step S13. That is, the gas supply valve 53 is opened. Then, gas is supplied to the pressure adjustment container 42‘ and the inside becomes the same pressure as the material supply port 35. In step S04, it is determined whether the weighing process has started. If it has started (YES), the outlet valve 47 is opened in step S05. Then, since there is no pressure difference between the pressure adjustment container 42‘ and the material supply port 35, the material in the pressure adjustment container 42‘ smoothly drops and is supplied to the material supply port 35. When it is determined in step S06 that the weighing process is completed (YES), step S14 is implemented. That is, the gas supply valve 53 is closed. Return to step S01.

[0030] [Second Embodiment] A second embodiment will be described. The injection molding machine according to the second embodiment is configured in the same manner as the injection molding machine 1 (see FIG. 1) according to the first embodiment, except for the injection device 3A shown in FIG. 7, in terms of the mold clamping device and the like. Explanation of the same configuration will be omitted. In the injection device 3A according to the second embodiment, the same configuration as the injection device 3 (see FIG. 2) according to the first embodiment, or the same configuration as the injection device 3' (see FIG. 5) according to a modification of the first embodiment, will be denoted by the same reference numerals and the explanation will be omitted.

[0031] Regarding the injection device 3A according to 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 section, that is, a material tank 60, in which a relatively large amount of material is stored, a pressure adjustment buffer section, that is, a pressure adjustment hopper 61, with a relatively large capacity, and a metering feeder 62 that accurately supplies the material.

[0032] A first valve, that is, an intake valve 64, is provided between the material tank 60 and the pressure adjustment hopper 61 and is configured to be opened and closed by an actuator 65. A second valve, that is, a discharge valve 67, is provided between the pressure adjustment hopper 61 and the metering feeder 62 and is configured to be opened and closed by an actuator 68. When the discharge valve 67 is opened, the material stored in the pressure adjustment hopper 61 is supplied to or discharged from the metering feeder 62. In this embodiment, the pressure adjustment hopper 61 is configured to store the material for a plurality of molding cycles.

[0033] The pressure adjustment hopper 61 is provided with a buffer section side gas supply section 51, and gas is supplied from a branched pipe 52 of the second pipe 31 of the gas supply device 23A via a gas supply valve 53. Further, the pressure adjustment hopper 61 is provided with an exhaust pipe 56, and a relief valve 55 and a suction pump 57 are provided in the exhaust pipe 56. As will be apparent from the material supply method described later, the pressure adjustment hopper 61, the receiving valve 64, and the discharge valve 67 in the second embodiment are similar to the pressure adjustment container 42' (see FIG. 5), the inlet valve 44, and the outlet valve 47 in the modification of the first embodiment, respectively. That is, they are configured to have the same operation. The pressure adjustment 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 has reached the lower limit.

[0034] The metering feeder 62 is connected to the material supply port 35 via a spacer 75, and is provided with a material delivery screw 77 for sending out the material inside. The material delivery screw 77 is rotated by a motor 78. The metering feeder 62 has a predetermined capacity and is configured to contain material for at least one molding cycle.

[0035] In the second embodiment, the material supply side gas supply port 37 is provided between the pressure adjustment hopper 61 and the metering feeder 62. Since gas is supplied from this position, the gas pressure from the metering feeder 62 to the material supply port 35 becomes uniform.

[0036] <Material Supply Method> In the injection device 3A according to the second embodiment, the material is supplied to the material supply port 35 of the heating cylinder 17 by the metering feeder 62. The metering feeder 62 is driven by the control device 4 (see FIG. 1) in synchronization with the metering process of the molding cycle. On the other hand, the supply or discharge of the material from the pressure adjustment hopper 61 to the metering feeder 62 does not need to be synchronized with the molding cycle and is supplied asynchronously. The method of supplying the material to the metering feeder 62 will be described as the material supply method according to the second embodiment. As described above, since the metering feeder 62 contains the material for more than one molding cycle, no problem occurs even if the supply of the material from the pressure adjustment hopper 61 to the metering feeder 62 is asynchronous with the molding cycle.

[0037] In explaining the material supply method according to the second embodiment, first, the first valve, that is, the receiving valve 64 is closed, and the second valve, that is, the discharge valve 67 is open. And the gas is being supplied from the buffer section side gas supply section 51 to the pressure adjustment hopper 61. In this state, the material in the pressure adjustment hopper 61 is freely supplied or discharged to the material supply port 35 side, that is, the metering feeder 62 side.

[0038] As shown in FIG. 8, the material supply method according to the second embodiment first has the control device 4 (see FIG. 1) perform step S21. That is, it is detected by the lower limit sensor 71 whether the material in the pressure adjustment hopper 61 (see FIG. 7) is decreasing. If there is still material (NO), step S21 is repeated. On the other hand, if the material reaches the lower limit (YES), the process proceeds to step S22. The control device 4 closes the gas supply valve 53 in step S22. Thereby, the supply of the gas to the pressure adjustment hopper 61 stops. Next, step S23 is performed to close the second valve, that is, the discharge valve 67. Thereby, the supply of the material from the pressure adjustment hopper 61 to the metering feeder 62 stops. The control device 4 opens the relief valve 55 in step S24. Then, the gas in the pressure adjustment hopper 61 is exhausted and the inside becomes atmospheric pressure.

[0039] The control device 4 (see FIG. 1) executes step S25. The first valve, i.e., the receiving valve 64, is opened. Then, the suction pump 57 is driven. As a result, the material is sucked from the material tank 60 and supplied to the pressure adjustment hopper 61. Air enters the pressure adjustment hopper 61 together with the material, but the air is discharged to the outside through the relief valve 55 and the suction pump 57. That is, only the material is stored in the pressure adjustment hopper 61. The control device 4 performs step S26 and determines, by means of the upper limit sensor 70, whether or not the stored material has reached the upper limit. If it has not yet reached the upper limit (NO), step S26 is repeated. On the other hand, if it has reached the upper limit (YES), the process proceeds to step S27.

[0040] The control device 4 (see FIG. 1) performs step S27 to close the receiving valve 64. Also, the suction pump 57 is stopped. As a result, the supply of the material from the material tank 60 stops. Subsequently, the control device 4 performs step S28 to close the relief valve 55. As a result, the pressure adjustment hopper 61 becomes airtight. The control device 4 opens the gas supply valve 53 in step S29. Gas is supplied into the pressure adjustment hopper 61, and the pressure of the gas becomes equal to that of the material supply port 35. The control device 4 performs step S30 to open the second valve, i.e., the discharge valve 67. That is, the supply of the material from the pressure adjustment hopper 61 to the metering feeder 62 resumes. The process returns to step S21.

[0041] Although the invention made by the present inventor has been specifically described based on the embodiments, it goes without saying that the present invention is not limited to the embodiments already described, and various modifications are possible without departing from the gist thereof. The plurality of examples described above can also be implemented in appropriate combinations.

Explanation of Reference Numerals

[0042] 1 Injection molding machine 2 Mold clamping device 3 Injection device 4 Control device 7 Fixed platen 8 Movable platen 9 Mold clamping housing 10 Tie bar 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 Cylinder 28 First pipe 30 First pressure reducing valve 31 Second pipe 32 Second pressure reducing valve 34 Central gas supply port 35 Material supply port 37 Material supply side gas supply port 38 Pressure gauge 39 Pressure gauge 41 Hopper 42 Pressure adjustment container 44 Inlet valve 45 Actuator 47 Outlet valve 48 Actuator 49 Seal member 51 Buffer section side gas supply port 52 Pipe 53 Gas supply valve 54 Exhaust section 55 Relief valve 56 Exhaust pipe 60 Material tank 61 Pressure adjustment hopper 62 Quantitative feeder 64 Receiving valve 65 Actuator 67 Discharge valve 68 Actuator 70 Upper limit sensor 71 Lower limit sensor 75 Spacer 77 Material delivery screw 78 Motor

Claims

1. A heating cylinder, a screw provided in the heating cylinder, a material supply device for supplying a material to a material supply port formed in the heating cylinder, and a gas supply device for supplying a gas, which is a physical foaming agent, to the heating cylinder, wherein the gas supply device is connected to a central side 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 a material and a pressure adjustment buffer unit, the pressure adjustment buffer unit is configured to store a predetermined amount of the material from the material storage unit and supply the stored material to the material supply port side, and an injection device in which a first valve is provided on the material storage unit side and a second valve is provided on the material supply port side in the pressure adjustment buffer unit.

2. The injection device includes a control device, the control device includes a supply preparation process and a supply process, the supply preparation process is configured to close the second valve and then open the first valve to store the material from the material storage unit in the pressure adjustment buffer unit, and the supply process is configured to close the first valve and then open the second valve to supply the material stored in the pressure adjustment buffer unit to the material supply port side. The injection device according to claim 1.

3. The injection device according to claim 1 or 2, wherein the pressure adjustment buffer unit and the material supply port are connected via a predetermined seal member so as to maintain airtightness.

4. The injection device according to claim 1 or 2, wherein the pressure adjustment buffer unit is configured to store a material for at least one molding cycle.

5. The injection device according to claim 1 or 2, wherein a sensor for detecting whether or not the material in the pressure adjustment buffer unit has reached a lower limit is provided in the pressure adjustment buffer unit.

6. The injection device according to claim 1 or 2, wherein a relief valve for releasing the internal pressure to atmospheric pressure is provided in the pressure adjustment buffer unit.

7. A buffer unit side gas supply unit is provided in the pressure adjustment buffer unit, and the gas supply device is connected to the buffer unit side gas supply unit via a gas supply valve. The injection device according to claim 1 or 2.

8. The injection device according to claim 1 or 2, wherein 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 central side gas supply port.

9. The injection device according to claim 1 or 2, wherein the material storage unit comprises a hopper.

10. The injection device according to claim 1 or 2, wherein the material supply device includes a metering feeder, and the metering feeder is provided between the pressure adjustment buffer unit and the material supply port.

11. The injection device according to claim 9, wherein the metering feeder has a capacity to hold a material for at least one molding cycle.

12. An injection device for injecting resin, A mold clamping device for clamping a mold, and The injection device includes a heating cylinder, A screw provided in the heating cylinder, A material supply device for supplying a material to a material supply port formed in the heating cylinder, A gas supply device for supplying a gas, which is a physical foaming agent, to the heating cylinder, and The gas supply device is connected to a central side 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 a material and a pressure adjustment buffer unit, The pressure adjustment buffer unit is configured to store a predetermined amount of the material from the material storage unit and supply the stored material to the material supply port side, The injection molding machine, wherein a first valve is provided on the material storage unit side and a second valve is provided on the material supply port side in the pressure adjustment buffer unit.

13. The injection molding machine includes a control device, The control device includes 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 adjustment buffer unit, The injection molding machine according to claim 12, wherein in the supply process, the first valve is closed, and then the second valve is opened to supply the material stored in the pressure adjustment buffer unit to the material supply port side.

14. The injection molding machine according to claim 12 or 13, wherein the pressure adjustment buffer unit and the material supply port are connected via a predetermined seal member to maintain airtightness.

15. A material supply method implemented in foam molding by an injection device, wherein the injection device includes a heating cylinder, a screw provided in the heating cylinder, 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, which is a physical foaming agent, to the heating cylinder, wherein the gas supply device is connected to a central side 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, wherein the material supply device includes a material storage unit that stores material and a pressure adjustment buffer unit in which the material is temporarily stored in a predetermined amount, wherein a first valve is provided on the material storage unit side and a second valve is provided on the material supply port side in the pressure adjustment buffer unit, wherein the material supply method includes a supply preparation step and a supply step, wherein in the supply preparation step, the second valve is closed, then the first valve is opened, and the material from the material storage unit is put into and stored in the pressure adjustment buffer unit, wherein in the supply step, the first valve is closed, then the second valve is opened, and the material stored in the pressure adjustment buffer unit is supplied to the material supply port side. A material supply method.

16. A sensor for detecting whether or not the material in the pressure adjustment buffer unit has reached the lower limit is provided in the pressure adjustment buffer unit, wherein the supply preparation step is performed when the sensor detects the lower limit of the material. The material supply method according to claim 15.

17. wherein the supply step is performed in a metering step among the molding cycles performed in the injection device, and the supply preparation step is performed in a step other than the metering step. The material supply method according to claim 15.

18. The material temporarily stored in the pressure adjustment buffer unit is set to be one or more times the amount for one molding cycle. The material supply method according to claim 15 or 16.

19. A relief valve for releasing the internal pressure of the pressure adjustment buffer unit to atmospheric pressure is provided, wherein in the supply preparation step, after closing the second valve, the relief valve is opened, and then the first valve is opened. The material supply method according to claim 15 or 16.

20. A buffer unit side gas supply unit is provided in the pressure adjustment buffer unit and is connected to the gas supply device via a gas supply valve. The material supply method according to claim 15 or 16, wherein in the supply process, after closing the first valve, the gas supply valve is opened, and then the second valve is opened.

21. 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 central side gas supply port. The material supply method according to claim 20, wherein the pressure of the gas supplied to the buffer section side gas supply section 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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