Injection molding machine

Abstract

To provide an injection molding machine capable of injecting molten resin with controlled degradation with a simple configuration.SOLUTION: An injection molding machine 1 includes a reservoir cylinder 10, a first injection member 12 housed inside the reservoir cylinder 10, and a molten resin feeder 6 connected to the reservoir cylinder 10 and pumping molten resin from the base end of the first injection member 12. In the reservoir cylinder 10, the molten resin is moved forward of the first injection member using the molten resin feeding force by the molten resin feeder 6, and the molten resin is accumulated in the front side of the interior space of the reservoir cylinder 10. The injection molding machine 1 then injects the molten resin from the tip of the reservoir cylinder 10 as the first injection member 12 moves forward.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to injection molding machines. [Background technology]

[0002] Conventionally, there has been known an injection molding machine that uses two cylinders to fill a mold device with molding material. For example, Patent Document 1 discloses an injection molding machine that includes a first cylinder (reservoir cylinder) and a second cylinder (injection cylinder) to which molten resin, which is the molding material, is supplied.

[0003] This injection molding machine advances the first injection member (first plunger) of the first cylinder, thereby discharging molten resin from the tip of the first cylinder and collecting the molten resin at the front of the internal space of the second cylinder.The injection molding machine then advances the second injection member (second plunger) of the second cylinder, thereby injecting the molten resin collected at the front of the second cylinder into a mold device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2022-27158 Summary of the Invention [Problem to be solved by the invention]

[0005] In a commonly known injection molding machine, a solid resin is supplied as a molding material to the base end of a cylinder, and heat is applied from outside the cylinder while a screw rotates inside the cylinder, thereby applying pressure and friction to the solid resin and melting the resin. On the other hand, in the injection molding machine disclosed in Patent Document 1, the resin as a molding material is melted before being supplied to the first cylinder, and the molten resin is supplied to the first cylinder.

[0006] In an injection molding machine such as that described in Patent Document 1, if molten resin is supplied to the base end of the first cylinder and a screw is used as the first injection member, the molten resin can be transported by the rotation of the screw within the first cylinder. However, in this case, excessive stress is applied to the molten resin supplied to the first cylinder due to the rotation of the screw, increasing the possibility of deterioration of the molten resin.

[0007] The present disclosure provides an injection molding machine that has a simple configuration and is capable of injecting molten resin with reduced deterioration. [Means for solving the problem]

[0008] According to one aspect of the present disclosure, there is provided an injection molding machine including a cylinder, an injection member housed inside the cylinder, and a molten resin supply device connected to the cylinder and pressurizing molten resin from a base end side of the tip of the injection member, wherein within the cylinder, the pressure of the molten resin from the molten resin supply device is used to move the molten resin forward of the injection member, and the molten resin is accumulated in front of the internal space of the cylinder, and the injection member moves forward to inject the molten resin from the tip of the cylinder. [Effects of the Invention]

[0009] According to one aspect, an injection molding machine can inject molten resin with reduced deterioration using a simple configuration. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a side view showing the overall configuration of an injection molding machine system according to a first embodiment. [Figure 2] 1 is a cross-sectional view schematically showing an injection unit of an injection molding machine according to a first embodiment. [Figure 3] Fig. 3(A) is a side view showing a first injection member according to the first embodiment, Fig. 3(B) is a side view showing a first injection member according to a first modified example, and Fig. 3(C) is a side view showing a first injection member according to a second modified example. [Figure 4] 4 is a flowchart showing the operation of an injection unit in an injection molding machine. [Figure 5] Fig. 5(A) is a cross-sectional view showing the operation of the reservoir cylinder in a reservoir storing step and the operation of the injection cylinder in an injection step, and Fig. 5(B) is a view showing the operation of the injection cylinder in a metering step. [Figure 6] FIG. 6 is a cross-sectional view schematically showing an injection unit of an injection molding machine according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0012] 1 is a side view showing the overall configuration of an injection molding machine system S according to the first embodiment. As shown in Fig. 1, the injection molding machine system S according to the first embodiment includes an injection molding machine 1, a molten resin supply device 6, a molten resin supply path 7, and a control valve 8.

[0013] The injection molding machine 1 includes a clamping device 2 that opens and closes a mold device (not shown), and an injection device 3 that injects molding material into the cavity space of the mold device. The injection molding machine 1 also includes an ejector device (not shown) that ejects a molded product molded by the mold device, a movement device (not shown) that moves the injection device 3 forward and backward relative to the mold device, and a frame 5 that supports each component of the injection molding machine 1. The injection molding machine 1 also includes a controller 4 that controls each component of the injection molding machine 1.

[0014] Based on the control commands of the controller 4, the mold clamping device 2 sequentially performs a mold closing process to bring the movable mold into contact with the fixed mold, a pressure increasing process to increase the mold clamping force, a mold clamping process to maintain the mold clamping force, a pressure release process to reduce the mold clamping force, and a mold opening process to separate the movable mold from the fixed mold.

[0015] The injection device 3 performs a metering process, a filling process, a pressure holding process, etc. based on control commands from the controller 4. Hereinafter, the filling process and the pressure holding process will be collectively referred to as the injection process. The operation of this injection device 3 will be described in detail later.

[0016] Based on a control command from the controller 4, the ejector device advances an ejector rod (not shown) from a standby position to an ejection position, ejects the molded product, and then performs an ejection process in which the ejector rod is retracted to the original standby position.

[0017] The moving device moves the injection device 3 forward and backward relative to the mold device. By moving the injection device 3 forward toward the mold device, the injection device 3 is pressed against the fixed mold of the mold device. By moving the injection device 3 backward, the injection device 3 moves away from the fixed mold of the mold device.

[0018] The controller 4 repeatedly performs the above-mentioned metering process, mold closing process, pressure increase process, mold clamping process, filling process, pressure dwell process, cooling process, pressure release process, mold opening process, and ejection process, thereby repeatedly manufacturing molded products. A series of operations required to obtain a molded product, for example, the operations from the start of a metering process to the start of the next metering process, is also called a molding cycle. The time required for one molding cycle is also called molding cycle time.

[0019] One molding cycle may include, for example, a metering process, a mold closing process, a pressurization process, a mold clamping process, a filling process, a pressure holding process, a cooling process, a depressurization process, a mold opening process, and an ejection process, in this order. The order here refers to the order in which each process starts. The filling process, the pressure holding process, and the cooling process are performed during the mold clamping process. The start of the mold clamping process may coincide with the start of the filling process. The end of the depressurization process coincides with the start of the mold opening process.

[0020] In order to shorten the molding cycle time, multiple processes may be performed simultaneously. For example, the metering process may be performed during the cooling process of the previous molding cycle, or during the mold clamping process. In this case, the mold closing process may be performed first in the molding cycle. The filling process may be started during the mold closing process. The ejection process may be started during the mold opening process. If the injection unit 3 is provided with a directional switching valve 50 (see FIG. 2), the mold opening process may be started during the metering process. This is because even if the mold opening process is started during the metering process, the molding material will not leak from the nozzle 40 of the injection unit 3 as long as the directional switching valve 50 closes the flow path of the injection unit 3.

[0021] Furthermore, one molding cycle may include steps other than the metering step, mold closing step, pressure increase step, mold clamping step, filling step, pressure holding step, cooling step, pressure release step, mold opening step, and ejection step.

[0022] The molten resin supplying device 6 supplies a molten resin (liquid molding material) that is a molten molding material (resin) to the injection device 3. Specifically, the molten resin supplying device 6 melts a solid recycled resin (for example, pelletized resin containing polyethylene terephthalate (PET)) while stirring it, and supplies it to the downstream molten resin supplying path 7. Furthermore, the molten resin supplying device 6 continuously supplies the molten resin to the molten resin supplying path 7, thereby imparting a pumping force to the molten resin that has been fed, and functions as a pumping device that pumps the molten resin using the pumping force of the molten resin supplied by the molten resin supplying device 6. Here, pumping the molten resin using the pumping force of the molten resin supply device 6 means that the molten resin in the cylinder is pumped by applying a pressure that allows the molten resin supplied to the base end side of the injection device 3 (reservoir cylinder 10) to move to the tip side of the injection device 3, even if there is no conveying member or the like that transports the molten resin to the tip side other than the pumping force of the molten resin by the molten resin supply device 6, or even if there is a conveying member or the like that transports the molten resin to the tip side other than the pumping force of the molten resin by the molten resin supply device 6, but the conveying member is stopped or otherwise does not apply force to the molten resin.

[0023] The molten resin supply path 7 is a path for supplying the molten resin from the molten resin supply device 6 to the injection device 3. The molten resin supply path 7 may include, for example, a pipe through which the molten resin flows, a heat insulating material covering the pipe, a heater for keeping the molten resin flowing through the pipe warm, and the like.

[0024] The control valve 8 is provided in the molten resin supply path 7 and is communicatively connected to the controller 4, and switches between supplying and stopping the supply of molten resin to the injection device 3. As this control valve 8, for example, an on-off valve can be used.

[0025] 1 shows a configuration in which one injection molding machine 1 is connected to the molten resin supply path 7, but the configuration is not limited to this and the injection molding machine system S may be configured in which multiple injection molding machines 1 are connected to the molten resin supply path 7. Also, while FIG. 1 shows a configuration in which one molten resin supply device 6 is connected to the molten resin supply path 7, the configuration is not limited to this and the injection molding machine system S may be configured in which multiple molten resin supply devices 6 are connected to the molten resin supply path 7.

[0026] <Configuration of injection device 3 according to first embodiment> Next, the injection unit 3 of the injection molding machine 1 will be described with reference to Fig. 2. Fig. 2 is a cross-sectional view that schematically shows the injection unit 3 of the injection molding machine 1 according to the embodiment.

[0027] The injection device 3 of the injection molding machine 1 uses two cylinders to inject molten resin, which is the molding material, into the mold device described above. Specifically, the injection device 3 includes a reservoir cylinder (first cylinder) 10, a first injection member 12, an injection cylinder (second cylinder) 20, and a second injection member (second-cylinder-side injection member) 22. The injection device 3 also includes a first injection member drive unit 15 that operates the first injection member 12, and a second injection member drive unit 25 that operates the second injection member 22. The injection device 3 also includes a supply connector 30, a connection unit 35, a nozzle 40, a directional switching valve 50, and a control unit 80.

[0028] The reservoir cylinder 10 is formed in a cylindrical shape extending horizontally. A connection part 35 is connected to the tip of the reservoir cylinder 10, while a first injection member drive part 15 is installed at the base end of the reservoir cylinder 10. The reservoir cylinder 10 has a hole part 10h located closer to the base end than the tip of the first injection member 12, and molten resin is introduced into the internal space through this hole part 10h. A supply connector 30 is provided on the outer circumferential surface of the reservoir cylinder 10, and is a connector that communicates with the hole part 10h and is connected to the molten resin supply path 7. In addition, a heating device (not shown) that heats or keeps warm the molten resin supplied to the internal space may be installed on the cylindrical wall that constitutes the reservoir cylinder 10.

[0029] As described above, the molten resin supply device 6 has the function of pressure-feeding molten resin toward the downstream molten resin supply path 7. Therefore, the injection device 3 pressure-feeds molten resin from the molten resin supply device 6 through the molten resin supply path 7, the supply connector 30, and the hole 10h into the internal space of the reservoir cylinder 10. The molten resin supplied to the internal space of the reservoir cylinder 10 receives the pressure-feeding force of the molten resin continuously delivered from the upstream side (molten resin supply path 7), and flows toward the front of the reservoir cylinder 10. In other words, the molten resin supplied to the reservoir cylinder 10 from the external molten resin supply device 6 moves due to the pressure-feeding force and accumulates in the front of the internal space of the reservoir cylinder 10.

[0030] FIG. 3(A) is a side view showing the first injection member 12 according to the first embodiment. FIG. 3(B) is a side view showing the first injection member 12A according to a first modified example. FIG. 3(C) is a side view showing the first injection member 12B according to a second modified example. As shown in FIG. 3(A), the first injection member 12 is formed as a solid rod member and configured as a screw that is provided so as to be able to advance and retreat within the internal space of the reservoir cylinder 10. The axis of the first injection member 12 is arranged coaxially with the axis of the reservoir cylinder 10.

[0031] However, the first injection member 12 according to the embodiment includes a shaft body 121 extending in the axial direction of the reservoir cylinder 10. However, the shaft body 121 does not include a spiral flight on its outer circumferential surface, and is configured not to rotate about its axis. As described above, the molten resin in the reservoir cylinder 10 can move forward in the internal space by the pumping force from the molten resin supply device 6, so the molten resin can be accumulated in the front of the internal space even if the first injection member 12, which includes flights, does not rotate about its axis. Note that the first injection member 12 may be configured to rotate about its axis in order to prevent the molten resin from adhering or accumulating on a specific location on the outer circumferential surface.

[0032] The outer peripheral surface of barrel body 121 of first injection member 12 is formed into a smooth curved surface without any irregularities. The outer diameter (diameter) of barrel body 121 is set smaller than the outer diameter of second injection member 22 described below. This forms a constant gap between barrel body 121 and the cylindrical wall of reservoir cylinder 10 over the entire circumferential direction. For example, the outer diameter of barrel body 121 may be set in the range of approximately 1 / 2 to 9 / 10 of the inner diameter (diameter) of reservoir cylinder 10.

[0033] In addition, a backflow prevention assembly 125, which combines a screw head 122, a backflow prevention ring 123, a seal ring 124, etc., is provided at the tip of the first injection member 12. This backflow prevention assembly 125 allows the molten resin to move toward the tip side of the first injection member 12, while restricting the molten resin accumulated in the front of the internal space from flowing back toward the rear when the first injection member 12 moves forward.

[0034] The first injection member 12 is moved forward and backward (sliding) relative to the reservoir cylinder 10 by the first injection member drive unit 15. For example, in the reservoir storing step of supplying molten resin to the internal space of the reservoir cylinder 10, the first injection member 12 moves backward in accordance with the amount (pressure) of molten resin stored in the front of the reservoir cylinder 10. As a result, the reservoir cylinder 10 stores a target amount of molten resin in the internal space in front of the first injection member 12. Then, the first injection member 12 moves forward after the reservoir storing step, thereby extruding the molding material in the internal space of the reservoir cylinder 10 from the tip of the reservoir cylinder 10.

[0035] The first injection member driving unit 15 closes the base end of the reservoir cylinder 10 and holds the base end of the first injection member 12. For example, the first injection member driving unit 15 has an advance / retract motor 16, an encoder 17, and a pressure detection unit 18.

[0036] The advance / retract motor 16 advances and retracts the first injection member 12 along the axis of the reservoir cylinder 10. A motion conversion mechanism that converts the rotational motion of the advance / retract motor 16 into linear motion of the first injection member 12 is provided between the first injection member 12 and the advance / retract motor 16. A ball screw, for example, can be used as the motion conversion mechanism.

[0037] The encoder 17 detects the rotation of the advance / retract motor 16 and transmits the detection signal to the control unit 80. The control unit 80 calculates the position and movement speed of the first injection member 12 based on the detection signal of the encoder 17, and controls the operation of the first injection member 12 using these calculation results.

[0038] The pressure detector 18 is located in the transmission path between the reciprocating motor 16 and the first injection member 12. It detects the force transmitted between the reciprocating motor 16 and the first injection member 12 and transmits the detection signal to the control unit 80. The control unit 80 calculates the pressure of the first injection member 12 from the detected force and adjusts or monitors the pressure the first injection member 12 receives from the molding material (back pressure on the first injection member 12) and the pressure acting on the molding material from the first injection member 12. The pressure acting on the first injection member 12 corresponds to the pressure that the screw head 122 and backflow prevention ring 123 receive from the molding material at the tip end of the first injection member 12. Because there is a gap between the screw head 122 and the inner diameter of the reservoir cylinder 10, some of the molding material flows backward through the gap. This increases the pressure on the backflow prevention ring 123.

[0039] On the other hand, the injection cylinder 20 is formed in a cylindrical shape extending parallel (horizontally) to the reservoir cylinder 10. A directional switching valve 50 is connected to the tip of the injection cylinder 20, while a second injection member drive unit 25 is installed at the base end of the injection cylinder 20. Molten resin is supplied to the internal space of the injection cylinder 20 from the tip side via the directional switching valve 50. A heating device (not shown) may be installed on the cylindrical wall constituting the injection cylinder 20 to heat or heat the molten resin supplied to the internal space.

[0040] The second injection member 22 is formed as a solid rod member and configured as a plunger that is provided so as to be able to advance and retreat within the internal space of the injection cylinder 20. The axis of the second injection member 22 is arranged coaxially with the axis of the injection cylinder 20. The outer peripheral surface of the second injection member 22 is a smoothly curved surface, and its outer diameter is set to be the same as or slightly smaller than the internal diameter of the injection cylinder 20. This allows the second injection member 22 to advance and retreat (slide) relative to the injection cylinder 20. As the second injection member 22 advances and retreats, it moves the molding material supplied to the internal space of the injection cylinder 20.

[0041] The second injection member drive unit 25 closes the base end of the injection cylinder 20 and holds the base end of the second injection member 22. Similar to the first injection member drive unit 15, the second injection member drive unit 25 also has an advance / retract motor 26, an encoder 27, and a pressure detection unit 28.

[0042] The advance / retract motor 26 advances and retracts the second injection member 22 along the axis of the injection cylinder 20. A motion conversion mechanism that converts the rotational motion of the advance / retract motor 26 into linear motion of the second injection member 22 is provided between the second injection member 22 and the advance / retract motor 26. A ball screw, for example, can be used as the motion conversion mechanism.

[0043] The encoder 27 detects the rotation of the advance / retract motor 26 and transmits the detection signal to the control unit 80. The control unit 80 calculates the position and movement speed of the second injection member 22 based on the detection signal of the encoder 27, and controls the operation of the second injection member 22 using these calculation results.

[0044] The pressure detection unit 28 is provided in the transmission path between the advance / retract motor 26 and the second injection member 22, detects the force transmitted between the advance / retract motor 26 and the second injection member 22, and sends the detection signal to the control unit 80. The control unit 80 calculates the pressure of the second injection member 22 from the detected force, and adjusts or monitors the pressure that the second injection member 22 receives from the molding material (back pressure on the second injection member 22), the pressure that the second injection member 22 exerts on the molding material, etc.

[0045] The connecting part 35 is a member that connects the reservoir cylinder 10 and the directional switching valve 50, and allows the molten resin to flow through an internal flow path 35a. The flow path 35a of the connecting part 35 is formed so as to bend at an angle of 90° inside the block, allowing the molten resin in the reservoir cylinder 10 to flow smoothly toward the directional switching valve 50.

[0046] The nozzle 40 is installed at a position opposite the injection cylinder 20 in the directional control valve 50, and is formed in a cylindrical body that communicates with a flow path (runner, etc.) of the mold device. The nozzle 40 circulates the molten resin extruded from the injection cylinder 20 via the directional control valve 50 and injects it into the mold device. The mold device forms a molded product by solidifying the molten resin that has filled the cavity space from the nozzle 40.

[0047] The directional switching valve 50 is provided between the connection part 35, the injection cylinder 20, and the nozzle 40, and switches the flow of the molten resin. The directional switching valve 50 includes a valve box 51, a valve element 52, and a valve element drive part (not shown).

[0048] The valve box 51 is formed in a substantially rectangular parallelepiped shape and houses the valve element 52. The valve box 51 has a supply-side connection port 53 that communicates with the flow path of the connection part 35, an injection cylinder connection port 54 that communicates with the internal space of the injection cylinder 20, and a nozzle connection port 55 that communicates with the inside of the nozzle 40. The injection cylinder connection port 54 and the nozzle connection port 55 are provided, for example, on opposite surfaces of the valve element 52 across the rotation center line. The supply-side connection port 53 is provided, for example, on a surface that is perpendicular to the axis connecting the injection cylinder connection port 54 and the nozzle connection port 55.

[0049] The valve element 52 rotates inside the valve box 51 to switch the directional switching valve 50 between a first state and a second state. In the first state, the valve element 52 communicates between the supply-side connection port 53 and the injection cylinder connection port 54, while closing the nozzle connection port 55. In the second state, the valve element 52 communicates between the injection cylinder connection port 54 and the nozzle connection port 55, while closing the supply-side connection port 53 (see also FIG. 4(B)). As a result, in the first state, molten resin can be moved from the connection portion 35 toward the injection cylinder 20. In the second state, molten resin can be moved from the injection cylinder 20 to the nozzle 40.

[0050] The valve element driver switches between the first state and the second state by rotating the valve element 52 within the valve box 51. The states of the valve element 52 are not limited to the first state and the second state. For example, the valve element 52 can be in a state in which it simultaneously closes the supply-side connection port 53, the injection cylinder connection port 54, and the nozzle connection port 55. The valve element 52 can also be in a state in which it communicates between the supply-side connection port 53 and the nozzle connection port 55, while closing the injection cylinder connection port 54.

[0051] The functions of the control unit 80 may be realized by any hardware, software, or combination thereof. For example, the control unit 80 may be a computer having a processor, memory, input / output interface, and communication interface (not shown). The processor is one or a combination of a central processing unit (CPU), a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a circuit made up of multiple discrete semiconductors, etc., and executes and processes programs stored in memory. The memory includes a main storage device made up of semiconductor memory, etc., and an auxiliary storage device made up of a disk, semiconductor memory (flash memory), etc.

[0052] The control unit 80 controls the operation of each component of the injection device 3 (first injection member drive unit 15, second injection member drive unit 25, directional switching valve 50, etc.) based on various commands from the controller 4 that controls the entire injection molding machine system S. Note that the injection molding machine system S may be configured such that the controller 4 also serves as the control unit 80 of the injection device 3 (i.e., directly controls the injection device 3).

[0053] The control unit 80 has a first injection member control unit 81, a second injection member control unit 82, and a flow path switching processing unit 83 built therein by the processor reading and executing the program from the memory. The first injection member control unit 81 controls the operation of the first injection member 12. The second injection member control unit 82 controls the operation of the second injection member 22. The flow path switching processing unit 83 controls each state of the directional switching valve 50 to switch the flow direction of the molten resin.

[0054] <Operation of injection unit 3> Next, the operation of the injection device 3 of the injection molding machine 1 will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the operation of the injection device 3 in the injection molding machine 1. Under the control of the control unit 80, the injection device 3 sequentially performs a reservoir storing process (step S101), a measuring process (step S102), a filling process (step S103), and a pressure holding process (step S104) shown in Fig. 4, and repeats these processes.

[0055] In the reservoir storing step, the injection device 3 stores a predetermined amount of molten resin in the front portion of the internal space of the reservoir cylinder 10. Then, in the metering step, the injection device 3 advances the first injection member 12 of the reservoir cylinder 10 to eject the molten resin from the reservoir cylinder 10 and store a predetermined amount of molten resin in the front portion of the internal space of the injection cylinder 20. In the filling step, the injection device 3 advances the second injection member 22 to fill the molten resin stored in the injection cylinder 20 into the cavity space in the mold device through the nozzle 40. In the pressure holding step, the injection device 3 extrudes the molten resin remaining in the injection cylinder 20 toward the mold device while maintaining the pressure of the molten resin in front of the second injection member 22 (holding pressure) at a set pressure. In addition, the injection molding machine 1 starts a cooling step after the pressure holding step to solidify the molding material in the cavity space. In order to shorten the molding cycle time, the injection molding machine 1 may perform the reservoir storing process during the injection process (filling process and filling process) of the previous molding cycle. Also, the injection molding machine 1 may perform the metering process during the cooling process.

[0056] Specific operations in each step will be described below with reference to Fig. 5. Fig. 5(A) is a cross-sectional view showing the operation of the reservoir storage step of the reservoir cylinder 10 and the operation of the injection step of the injection cylinder 20. Fig. 5(B) is a view showing the operation of the metering step of the injection cylinder 20.

[0057] In the reservoir storing step, the flow path switching processing unit 83 of the control unit 80 sets the valve element 52 of the directional switching valve 50 to the second state as shown in Fig. 5(A) . As described above, in the reservoir storing step, the injection cylinder 20 and the nozzle 40 need to be in communication with each other in order to perform the injection steps (filling step and pressure holding step) on the injection cylinder 20 side.

[0058] Then, in the reservoir storing process, the molten resin is pumped from the molten resin supply device 6 through the molten resin supply path 7, and the molten resin flows into the base end side of the internal space of the reservoir cylinder 10 via the supply connector 30. The molten resin that has flowed into the reservoir cylinder 10 is subjected to the pumping force of the molten resin from the molten resin supply device 6, and moves forward through the internal space of the reservoir cylinder 10 (around the first injection member 12). The molten resin that has moved to the front side of the internal space of the reservoir cylinder 10 is prevented from flowing out of the reservoir cylinder 10 because the flow path of the connection part 35 is blocked by the valve body 52 of the directional switching valve 50.

[0059] The first injection member 12 of the reservoir cylinder 10 is pushed by the molten resin moving toward the front side of the internal space, and thereby moves backward relative to the reservoir cylinder 10. Alternatively, the first injection member control unit 81 of the injection device 3 may control the advance / retract motor 16 based on the pressure of the molten resin pressure-fed from the molten resin supply device 6 during the reservoir storing step to move the first injection member 12 backward. For example, the first injection member control unit 81 may adjust the backward speed of the first injection member 12 so that the pressure of the molten resin detected by the pressure detection unit 18 matches the target pressure.

[0060] When a target amount of molten resin is accumulated in the front side of the internal space of the reservoir cylinder 10 in the reservoir storing process, the control unit 80 ends the reservoir storing process and starts the metering process (step S102 in FIG. 4). At this time, the flow path switching processing unit 83 of the control unit 80 controls the valve element driving unit of the directional switching valve 50 to set the valve element 52 to the first state as shown in FIG. 5(B). In other words, the flow path of the connection unit 35 and the internal space of the injection cylinder 20 are in communication via the directional switching valve 50, and molten resin can be supplied from the connection unit 35 to the injection cylinder 20.

[0061] Then, in the metering process, the first injection member control unit 81 of the control unit 80 drives the advance / retract motor 16 to advance the first injection member 12. At this time, the first injection member control unit 81 calculates the position or movement speed of the first injection member 12 based on the detection value of the encoder 17 and controls the movement speed of the first injection member 12. The first injection member 12 extrudes the molten resin in the internal space of the reservoir cylinder 10 by the backflow prevention assembly 125 and discharges it from the tip of the reservoir cylinder 10. The molten resin extruded from the reservoir cylinder 10 flows smoothly through the connection unit 35 and flows into the internal space of the injection cylinder 20 via the directional switching valve 50. As a result, the molten resin accumulates in front of the second injection member 22 in the internal space of the injection cylinder 20.

[0062] In the metering step, the control unit 80 of the injection device 3 may drive the advance / retract motor 26 via the second injection member control unit 82 to retract the second injection member 22 in accordance with the advancement of the first injection member 12. That is, when the molten resin extruded from the reservoir cylinder 10 flows into the injection cylinder 20, the second injection member 22 in the injection cylinder 20 is retracted by the driving force of the advance / retract motor 26. This reduces the pressure of the molten resin in the injection cylinder 20 compared to when the molten resin presses the second injection member 22 to retract it.

[0063] After the above-mentioned measurement step, the control unit 80 starts the filling step (step S103). Returning to Fig. 5(A), the flow path switching processing unit 83 of the control unit 80 controls the valve element driving unit of the directional switching valve 50 to set the valve element 52 to the second state. In other words, the internal space of the injection cylinder 20 and the flow path of the nozzle 40 are communicated via the directional switching valve 50, and the flow path of the connection unit 35 is blocked.

[0064] Then, in the filling step, the second injection member control unit 82 of the control unit 80 drives the advance / retract motor 26 to advance the second injection member 22 to a predetermined position. At this time, the second injection member control unit 82 calculates the position or movement speed of the second injection member 22 based on the detection value of the encoder 27, and controls the movement speed of the second injection member 22. The second injection member 22 discharges the molten resin that has accumulated in front of the second injection member 22 in the internal space of the injection cylinder 20 from the injection cylinder 20. The molten resin in the injection cylinder 20 moves to the nozzle 40 via the directional switching valve 50, flows through the flow path of the nozzle 40, and fills the cavity space in the mold device.

[0065] After the filling step, the control unit 80 starts a pressure holding step (step S104). In this case, the second injection member control unit 82 of the control unit 80 controls the rotation of the advance / retract motor 26 based on the detection value of the pressure detection unit 28 so as to keep the pressure (holding pressure) of the molten resin extruded by the second injection member 22 at a set pressure, thereby advancing the second injection member 22. This advancement of the second injection member 22 allows the second injection member 22 to push out the molten resin remaining in the internal space of the injection cylinder 20 toward the mold device.

[0066] As described above, the injection molding machine 1 can repeatedly manufacture molded products by interlocking the mold clamping device 2, ejector device, and moving device while performing the reservoir storage process, metering process, filling process, and pressure holding process in the injection device 3. The injection molding machine 1 can inject molten resin with reduced degradation using a simple configuration in which molten resin is pressure-fed from the base end of the reservoir cylinder 10 and stored therein. In other words, the flow of molten resin in the reservoir cylinder 10 is unidirectional, preventing stagnation of the molten resin and preventing deterioration of the molten resin due to stagnation. As a result, the quality of the injected molten resin is high, and the quality of the molded product can be improved.

[0067] Furthermore, the first injection member 12 is provided with a backflow prevention assembly 125 (screw head 122, backflow prevention ring 123, seal ring 124), which prevents backflow of molten resin when the first injection member 12 moves forward. This allows the first injection member 12 to accurately discharge molten resin into the injection cylinder 20. Furthermore, the injection molding machine 1 does not require the installation of a valve or the like to prevent backflow.

[0068] Furthermore, the first injection member 12 has a shaft body 121 with a curved surface without any irregularities, which eliminates the need for kneading of the molten resin and reduces the impact of kneading on the molten resin. Furthermore, the absence of flights simplifies the structure of the first injection member 12, reducing manufacturing costs. In particular, since recycled resins are prone to deterioration, pressure-feeding the molten resin prevents retention and eliminates shearing caused by flights, significantly reducing the deterioration of the recycled resin. The molding material injected by the injection molding machine 1 is not limited to recycled resin, and various materials may be used. Even in this case, the first injection member 12 can suppress deterioration due to the conveying load of the screw. However, applying the first injection member 12 to an injection device 3 that conveys molten resin rather than solid resin can significantly reduce the deterioration of the molten resin.

[0069] The injection molding machine 1 according to the present disclosure is not limited to the above-described embodiment and may have various modifications. For example, the injection molding machine 1 is not limited to the first injection member 12 applied to the reservoir cylinder 10 being a screw without flights as described above, and various other structures may be applied. Below, several other configurations of the first injection member 12 will be described with reference to Figures 3(B) and 3(C).

[0070] 3(B), the first injection member 12A according to the first modification is different from the first injection member 12 described above in that it includes a spiral flight 126 formed to protrude low from the outer peripheral surface of the shaft body 121. That is, in the above embodiment, the molten resin is pressure-fed by the molten resin supply device 6, so the first injection member 12A does not include a flight, but the first injection member 12A may include a flight 126 that can assist in conveying the molten resin while suppressing deterioration of the molten resin. In this case, the first injection member 12A is configured to rotate about its axis within the reservoir cylinder 10.

[0071] The flight 126 of the first injection member 12 is appropriately designed, for example, to have a small outer diameter (low height), a wide pitch, a small number or proportion of blades, etc. compared to the flights of a general screw that moves the molding material while melting, kneading, etc. Figure 4(B) shows an example in which the outer diameter of the flight 126 is small, and for example, the outer diameter of the flight 126 is set smaller than the outer diameter of the backflow prevention ring 123.

[0072] Furthermore, when a flight 126 is provided, it is preferable that the length L of the portion where the flight 126 is provided be short relative to the overall length of the screw. For example, when the inner diameter of the reservoir cylinder 10 is D and the length of the flight 126 is L, it is preferable that the length L of the flight 126 be set so that L / D≦15. By shortening the length L of the flight 126 on the shaft body 121, the area where the flight 126 affects the molten resin can be reduced, thereby suppressing deterioration of the molten resin. Furthermore, the first injection member 12 having the flight 126 can smoothly move the molten resin pressure-fed into the reservoir cylinder 10 forward. The reason why the length L of the flight 126 should not be too long compared to the inner diameter D of the reservoir cylinder 10 is independent of the outer diameter of the flight 126, whether the outer diameter is approximately the same as the inner diameter D of the reservoir cylinder 10 or smaller (for example, less than half the distance between the shaft body 121 and the inner circumferential surface of the reservoir cylinder 10). However, irregularities that do not promote deterioration of the molten resin and have a height of less than 5% of the distance between the shaft body 121 and the inner surface of the reservoir cylinder 10 are not considered to be flights as defined here, even if they are arranged in a spiral shape.

[0073] 3(C), the first injection member 12B according to the second modification differs from the first injection members 12 and 12A described above in that it does not include a backflow prevention assembly 125 at the tip of the barrel body 121. As described above, in the reservoir cylinder 10, the molten resin is continuously pressure-fed from the molten resin supply path 7. Therefore, even if the first injection member 12B without the backflow prevention assembly 125 is used and the first injection member 12B is extruded after the reservoir storing step, backflow of the molten resin toward the base end side can be suppressed, and the molten resin can be discharged from the tip of the reservoir cylinder 10.

[0074] <Configuration and Operation of Injection Device 3A According to Second Embodiment> 6 is a cross-sectional view schematically showing an injection unit 3A of an injection molding machine 1A according to a second embodiment. The injection molding machine 1A according to the second embodiment differs from the injection molding machine 1 according to the first embodiment in that it includes one injection cylinder 20 and one injection member 23, and that molten resin is pressure-fed to the injection cylinder 20 from a position behind the tip of the injection member 23. In this way, even when one injection cylinder 20 is used, the injection molding machine 1A can effectively store the molten resin at the front side of the internal space of the injection cylinder 20 (at the front side of the injection member 23) by pressure-fed the molten resin from the base end side of the injection cylinder 20.

[0075] The tip of the injection cylinder 20 does not have a valve body, but has a connection part 36 for connection to the nozzle 40. The injection member 23 can be configured similarly to the first injection members 12, 12A, 12B according to the first embodiment. For example, FIG. 6 shows an example of a configuration in which the barrel body 121 does not have flights but has a backflow prevention assembly 125.

[0076] In this injection molding machine 1A, in the metering process of storing molten resin in the injection cylinder 20, similar to the reservoir storing process described above, the molten resin being pumped moves forward inside the injection cylinder 20. Then, in the injection process (filling process, pressure holding process), the injection molding machine 1A moves the injection member 23 forward, thereby being able to inject the molten resin stored in the front into the mold device.

[0077] The injection molding machines 1, 1A according to the embodiments disclosed herein are illustrative in all respects and are not limiting. The embodiments can be modified and improved in various ways without departing from the spirit and scope of the appended claims. The features described in the above embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent. [Explanation of symbols]

[0078] 1, 1A injection molding machine 6. Molten resin supply device 10 Reservoir cylinder 12, 12A, 12B First injection member 121 Shaft body 125 Backflow prevention assembly 125 126 flights 20 injection cylinder 22 second injection member 23 Injection member 80 Control Unit

Claims

1. A cylinder; an injection member housed within the cylinder; a molten resin supplying device connected to the cylinder and pressure-feeding molten resin from a base end side of the tip of the injection member, In the cylinder, the molten resin is moved forward of the injection member by using a pumping force of the molten resin by the molten resin supply device, and the molten resin is accumulated in a front portion of an internal space of the cylinder, The injection member moves forward to inject the molten resin from the tip of the cylinder. Injection molding machine.

2. The cylinders include a first cylinder to which the molten resin is supplied from the molten resin supply device, and a second cylinder to which the molten resin is supplied from the first cylinder and which injects the molten resin into a mold device.

2. The injection molding machine according to claim 1.

3. The first cylinder has the injection member therein, the second cylinder includes a second cylinder side injection member into which the molten resin supplied from the first cylinder flows from a tip end and retreats, The second cylinder side injection member moves forward, thereby injecting the molten resin from the tip of the second cylinder into the mold device.

3. The injection molding machine according to claim 2.

4. A control unit is provided to control the injection member and the second cylinder side injection member, the control unit pumps the molten resin in the internal space of the first cylinder to accumulate the molten resin in a reservoir at a front portion of the internal space of the first cylinder; a measuring step of, after the reservoir storing step, moving the injection member forward to eject the molten resin from the first cylinder and storing the molten resin in a front portion of an internal space of the second cylinder; an injection step of, after the metering step, moving the second cylinder side injection member forward to inject the molten resin from the second cylinder into the mold device; The reservoir storing step is performed while the ejection step is performed.

4. The injection molding machine according to claim 3.

5. the injection member extrudes the molten resin forward and has a backflow prevention assembly at a tip end thereof for preventing the molten resin from flowing back toward a base end side; 5. The injection molding machine according to claim 1 .

6. The injection member has a shaft body extending in an axial direction of the cylinder, The outer circumferential surface of the shaft body is formed into a curved surface without irregularities.

5. The injection molding machine according to claim 1 .

7. The injection member has a shaft body extending in an axial direction of the cylinder, A spiral flight is formed on the outer circumferential surface of the shaft body.

5. The injection molding machine according to claim 1 .

8. The molten resin supplying device melts recycled resin and supplies it to the cylinder.

5. The injection molding machine according to claim 1 .

9. A cylinder, an injection member housed within the cylinder and having a flight; a molten resin supplying device for supplying molten resin to the cylinder, The molten resin in the cylinder is moved by the flight that rotates by rotating the injection member and the pressure of the molten resin pressure-fed from the molten resin supply device, The injection member moves forward to inject the molten resin from the tip of the cylinder. Injection molding machine.

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