Injection molding machine

Abstract

The invention relates to an injection molding machine which can inject molten resin with a simple structure, wherein deterioration of the molten resin is inhibited. An injection molding machine (1) is provided with: a storage cylinder (10); a first injection member (12) housed inside the storage cylinder (10); and a molten resin supply device (6) that is connected to the storage cylinder (10) and that pressure-feeds the molten resin from the base end side of the first injection member (12). In the storage cylinder (10), the molten resin is moved to a position closer to the front than the first injection part by using the pressure feeding force of the molten resin supply device (6) to the molten resin, and the molten resin is stored in the front of the internal space of the storage cylinder (10). Furthermore, the injection molding machine (1) injects the molten resin from the tip of the storage cylinder (10) by advancing the first injection member (12).

Description

Technical Field

[0001] This application claims priority based on Japanese Patent Application No. 2023-174294 filed on October 6, 2023. The entire contents of the Japanese Patent Application are incorporated herein by reference.

[0002] The invention relates to an injection molding machine. Background Art

[0003] Injection molding machines that use two cylinders to fill a mold device with molding material are known in the past. For example, Patent Document 1 discloses an injection molding machine that includes a first cylinder (storage cylinder) and a second cylinder (injection cylinder) to which molten resin, which is a molding material, is supplied.

[0004] The injection molding machine is a machine that discharges molten resin from the front end of the first cylinder by advancing the first injection component (first plunger) of the first cylinder, and accumulates the molten resin in front of the internal space of the second cylinder. Furthermore, the injection molding machine advances the second injection component (second plunger) of the second cylinder to inject the molten resin accumulated in front of the second cylinder into the mold device.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-27158

[0006] However, a generally known injection molding machine supplies a solid resin as a molding material to the base end of a cylinder, applies heat from the outside of the cylinder, and rotates a screw inside the cylinder, thereby applying pressure and friction to the solid resin to melt the resin. On the other hand, in the injection molding machine disclosed in Patent Document 1, the molding material, i.e., the resin, is melted before being supplied to the first cylinder, and the molten resin is supplied to the first cylinder.

[0007] Assuming that in an injection molding machine such as Patent Document 1, 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 conveyed in the first cylinder by the rotation of the screw. However, in this case, excessive pressure is applied to the molten resin supplied to the first cylinder due to the rotation of the screw, and the possibility of deterioration of the molten resin increases. Summary of the invention

[0008] The present invention provides an injection molding machine capable of injecting molten resin with suppressed degradation by means of a simple structure.

[0009] According to one embodiment of the present invention, an injection molding machine is provided, which includes: a cylinder body; an injection component housed inside the cylinder body; and a molten resin supply device connected to the cylinder body, for pressurizing molten resin from a position closer to the base end side than the front end of the injection component, wherein in the cylinder body, the molten resin is moved to a position further forward than the injection component by using the pressure force of the molten resin supply device on the molten resin, so that the molten resin is accumulated in front of the internal space of the cylinder body, and the molten resin is injected from the front end of the cylinder body by the advancement of the injection component.

[0010] Effects of the Invention

[0011] According to one embodiment, an injection molding machine can inject molten resin whose degradation is suppressed by a simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a side view showing the overall structure of the injection molding machine system according to the first embodiment.

[0013] Figure 2 It is a cross-sectional view schematically showing an injection device of the injection molding machine according to the first embodiment.

[0014] Figure 3 (A) is a side view showing the first injection component according to the first embodiment. Figure 3 (B) is a side view showing the first injection component according to the first modification. Figure 3 (C) is a side view showing the first injection component involved in the second modification.

[0015] Figure 4 This is a flowchart showing the operation of the injection device in the injection molding machine.

[0016] Figure 5 (A) is a cross-sectional view showing the operation of the reservoir storing process of the reservoir cylinder and the injection process of the injection cylinder. Figure 5 (B) is a diagram showing the operation of the metering process of the injection cylinder.

[0017] Figure 6 It is a cross-sectional view schematically showing an injection device of an injection molding machine according to a second embodiment.

[0018] Explanation of symbols

[0019] 1, 1A-injection molding machine, 6-molten resin supply device, 10-storage cylinder, 12, 12A, 12B-first injection component, 121-axis body, 125-backflow prevention component, 126-scraper, 20-injection cylinder, 22-second injection component, 23-injection component, 80-control unit. DETAILED DESCRIPTION

[0020] Hereinafter, the mode for implementing the present invention will be described with reference to the drawings. In each of the drawings, the same components are denoted by the same reference numerals, and repeated description may be omitted.

[0021] Figure 1 1 is a side view showing the overall structure of the injection molding machine system S according to the first embodiment. Figure 1 As shown, 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 .

[0022] The injection molding machine 1 includes a clamping device 2 for opening and closing a mold device (not shown) and an injection device 3 for injecting a molding material into a cavity space of the mold device. In addition, the injection molding machine 1 has an ejector device (not shown) for ejecting a molded product molded by the mold device, a moving device (not shown) for moving the injection device 3 forward and backward relative to the mold device, and a frame 5 for supporting various components of the injection molding machine 1. In addition, the injection molding machine 1 has a controller 4 for controlling various components of the injection molding machine 1.

[0023] The mold clamping device 2 sequentially performs a mold closing process for bringing the movable mold into contact with the fixed mold, a pressurizing process for increasing the mold clamping force, a mold clamping process for maintaining the mold clamping force, a depressurizing process for reducing the mold clamping force, and a mold opening process for separating the movable mold from the fixed mold according to control instructions from the controller 4.

[0024] The injection device 3 performs metering, filling, and pressure-maintaining steps according to control instructions from the controller 4. Hereinafter, the filling and pressure-maintaining steps are collectively referred to as injection steps. The operation of the injection device 3 will be described in detail later.

[0025] The ejector device performs the following ejection process according to the control command of the controller 4: the ejector rod (not shown) is moved forward from the standby position to the ejection position to eject the molded product, and then the ejector rod is moved back to the original standby position.

[0026] 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 is separated from the fixed mold of the mold device.

[0027] The controller 4 repeatedly performs the above-mentioned metering process, mold closing process, pressure increasing process, mold closing process, filling process, pressure holding process, cooling process, pressure releasing process, mold opening process and ejection process, thereby repeatedly manufacturing the molded product. A series of actions for obtaining the molded product, for example, the actions from the start of the metering process to the start of the next metering process, are also referred to as a molding cycle. In addition, the time required for one molding cycle is also referred to as the molding cycle time.

[0028] For example, a molding cycle sequentially performs metering process, mold closing process, pressure increasing process, mold closing process, filling process, pressure holding process, cooling process, pressure releasing process, mold opening process and ejection process. The order here is the order in which each process starts. The filling process, pressure holding process and cooling process are performed during the mold closing process. The start of the mold closing process can coincide with the start of the filling process. The end of the pressure releasing process coincides with the start of the mold opening process.

[0029] In addition, in order to shorten the molding cycle time, multiple processes can be performed simultaneously. For example, the metering process can be performed during the cooling process of the previous molding cycle, or during the mold closing process. In this case, the mold closing process can be performed at the beginning of the molding cycle. In addition, the filling process can be started during the mold closing process. In addition, the ejection process can be started during the mold opening process. A reversing valve 50 (see Figure 2 ), the mold opening process can also be started in the metering process. Even if the mold opening process is started in the metering process, if the reversing valve 50 closes the flow path of the injection device 3, the molding material will not leak from the nozzle 40 of the injection device 3.

[0030] In addition, a primary molding cycle may include processes other than the metering process, the mold closing process, the pressure increasing process, the mold clamping process, the filling process, the pressure holding process, the cooling process, the pressure releasing process, the mold opening process, and the ejection process.

[0031] The molten resin supply device 6 supplies the molten molding material (resin), i.e., molten resin (liquid molding material), to the injection device 3. Specifically, the molten resin supply device 6 melts the solid recovered resin (for example, a resin obtained by pelletizing a resin containing polyethylene terephthalate (PET)) while stirring it, and supplies it to the molten resin supply path 7 on the downstream side. In addition, the molten resin supply device 6 functions as a pressure-feeding device that applies a pressure-feeding force to the molten resin supplied by continuously supplying the molten resin to the molten resin supply path 7, and uses the pressure-feeding force of the molten resin supply device 6 on the molten resin to pressure-feed the molten resin. Here, using the pressure-feeding force of the molten resin supply device 6 on the molten resin to press-feed the molten resin means that even if there is no conveying component for conveying the molten resin to the front end side in addition to the pressure-feeding force of the molten resin supply device 6 on the molten resin, or even if there is a conveying component for conveying the molten resin to the front end side in addition to the pressure-feeding force of the molten resin supply device 6 on the molten resin, but the conveying component is stopped and the conveying component does not apply force to the molten resin, a pressure is applied to press-feed the molten resin in the cylinder body so as to move the molten resin supplied to the base end side of the injection device 3 (storage cylinder 10) to the front end side of the injection device 3.

[0032] The molten resin supply path 7 is a path for supplying 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, an insulating material covering the pipe, a heater for keeping the molten resin flowing in the pipe warm, and the like.

[0033] The control valve 8 is provided on the molten resin supply path 7, is communicably connected to the controller 4, and switches supply and stop of the molten resin to the injection device 3. As the control valve 8, for example, an on-off valve can be applied.

[0034] In addition, Figure 1 The middle figure shows a structure in which one injection molding machine 1 is connected to the molten resin supply path 7, but the present invention is not limited thereto, and the injection molding machine system S may also be a structure in which a plurality of injection molding machines 1 are connected to the molten resin supply path 7. Figure 1 The middle figure shows a structure in which one molten resin supply device 6 is connected to the molten resin supply path 7 , but the present invention is not limited thereto, and the injection molding machine system S may also have a structure in which a plurality of molten resin supply devices 6 are connected to the molten resin supply path 7 .

[0035] <Structure of injection device 3 according to first embodiment>

[0036] Next, refer to Figure 2 The injection device 3 of the injection molding machine 1 will be described. Figure 2It is a cross-sectional view schematically showing the injection device 3 of the injection molding machine 1 according to the embodiment.

[0037] The injection device 3 of the injection molding machine 1 uses two cylinders to inject the molding material, i.e., molten resin, into the above-mentioned mold device. Specifically, the injection device 3 includes a storage cylinder (first cylinder) 10, a first injection component 12, an injection cylinder (second cylinder) 20, and a second injection component (second cylinder side injection component) 22. In addition, the injection device 3 includes a first injection component drive unit 15 that operates the first injection component 12 and a second injection component drive unit 25 that operates the second injection component 22. In addition, the injection device 3 has a supply connector 30, a connecting part 35, a nozzle 40, a reversing valve 50, and a control unit 80.

[0038] The storage cylinder 10 is formed into a cylindrical shape extending in the horizontal direction. A connection portion 35 is connected to the front end of the storage cylinder 10, and a first injection component driving portion 15 is provided at the base end of the storage cylinder 10. The storage cylinder 10 has a hole portion 10h at a position closer to the base end than the front end of the first injection component 12, and molten resin is introduced into the internal space through the hole portion 10h. A connector, namely a supply connector 30, which is connected to the hole portion 10h and connected to the molten resin supply path 7 is provided on the outer peripheral surface of the storage cylinder 10. In addition, a heating device (not shown) for keeping the molten resin supplied to the internal space warm or heating it may be provided on the wall of the cylinder constituting the storage cylinder 10.

[0039] As described above, the molten resin supply device 6 has a function of pressurizing the molten resin toward the molten resin supply path 7 on the downstream side. Therefore, the injection device 3 pressurizes the molten resin from the molten resin supply device 6 to the internal space of the storage cylinder 10 via the molten resin supply path 7, the supply connector 30 and the hole portion 10h. The molten resin supplied to the internal space of the storage cylinder 10 flows to the front of the storage cylinder 10 by receiving the pressurizing force of the molten resin continuously fed from the upstream side (molten resin supply path 7). In other words, the molten resin supplied to the storage cylinder 10 from the external molten resin supply device 6 moves by the pressurizing force and accumulates in the front of the internal space of the storage cylinder 10.

[0040] Figure 3 (A) is a side view showing the first injection component 12 according to the first embodiment. Figure 3 (B) is a side view showing the first injection component 12A according to the first modification. Figure 3 (C) is a side view showing the first injection component 12B involved in the second modification. Figure 3 As shown in (A), the first injection member 12 is formed as a solid rod member and is configured as a screw provided in an advanceable and retreatable manner in the internal space of the storage cylinder 10. The axis of the first injection member 12 and the axis of the storage cylinder 10 are arranged coaxially.

[0041] However, the first injection component 12 involved in the embodiment has an axis body 121 extending in the axial direction of the storage cylinder 10. However, the axis body 121 is configured to not have a spiral scraper on the outer peripheral surface and does not rotate around the axis. As described above, since the molten resin in the storage cylinder 10 can move forward in the internal space by the pressure-feeding force from the molten resin supply device 6, even if the first injection component 12 with a scraper does not rotate around the axis, the molten resin can be accumulated in front of the internal space. In addition, the first injection component 12 can also be configured to rotate around the axis to prevent the molten resin from adhering to and accumulating on the outer peripheral surface of a specific portion.

[0042] The outer peripheral surface of the shaft body 121 of the first injection part 12 is formed as a smooth curved surface without unevenness. The outer diameter (diameter) of the shaft body 121 is set to be smaller than the outer diameter of the second injection part 22 described later. As a result, a constant gap is formed between the shaft body 121 and the cylinder wall of the storage cylinder 10 over the entire circumference. For example, the outer diameter of the shaft body 121 can be set to be within a range of about 1 / 2 to 9 / 10 relative to the inner diameter (diameter) of the storage cylinder 10.

[0043] Furthermore, a backflow prevention assembly 125 composed of a screw head 122, a backflow prevention ring 123, and a seal ring 124 is provided at the front end of the first injection part 12. The backflow prevention assembly 125 allows the molten resin to move toward the front end side of the first injection part 12, and on the other hand, restricts the molten resin accumulated in the front of the internal space from flowing back to the rear side when the first injection part 12 moves forward.

[0044] The first injection component 12 is moved forward and backward (slid) relative to the storage cylinder 10 by the first injection component driving unit 15. For example, in the implementation of the reservoir storage process of supplying molten resin to the internal space of the storage cylinder 10, the first injection component 12 is moved backward according to the storage amount (pressure) of the molten resin stored in front. As a result, the storage cylinder 10 accumulates a target storage amount of molten resin in the internal space in front of the first injection component 12. In addition, the first injection component 12 advances after the reservoir storage process, thereby squeezing the molding material in the internal space of the storage cylinder 10 out of the front end of the storage cylinder 10.

[0045] The first injection member driving unit 15 closes the base end of the storage cylinder 10 and holds the base end of the first injection member 12. The first injection member driving unit 15 includes an advance / retract motor 16, an encoder 17, and a pressure detection unit 18, for example.

[0046] The advance / retract motor 16 advances / retracts the first injection component 12 along the axis of the storage cylinder 10. A motion conversion mechanism is provided between the first injection component 12 and the advance / retract motor 16 to convert the rotational motion of the advance / retract motor 16 into the linear motion of the first injection component 12. The motion conversion mechanism may be, for example, a ball screw.

[0047] The encoder 17 detects the rotation of the forward / retract motor 16 and sends the detection signal to the control unit 80. The control unit 80 calculates the position and moving speed of the first injection component 12 based on the detection signal of the encoder 17 and controls the operation of the first injection component 12 using the calculation results.

[0048] The pressure detection unit 18 is provided on the transmission path between the advance / retract motor 16 and the first injection component 12, detects the force transmitted between the advance / retract motor 16 and the first injection component 12, and sends its detection signal to the control unit 80. The control unit 80 calculates the pressure of the first injection component 12 based on the detected force, and adjusts or monitors the pressure (back pressure for the first injection component 12) received by the first injection component 12 from the molding material, the pressure acting on the molding material from the first injection component 12, and the like. The pressure applied to the first injection component 12 is equivalent to the pressure received by the molding material located at the front end side of the first injection component 12 by the screw head 122 and the backflow prevention ring 123. Since there is a gap between the screw head 122 and the inner diameter of the storage cylinder 10, a part of the molding material flows backward in the gap. As a result, the pressure applied to the backflow prevention ring 123 becomes larger.

[0049] On the other hand, the injection cylinder 20 is formed into a cylindrical shape extending parallel to (horizontally) the storage cylinder 10. A reversing valve 50 is connected to the front end of the injection cylinder 20, and a second injection member driving unit 25 is provided at the base end of the injection cylinder 20. The molten resin is supplied from the front end side to the internal space of the injection cylinder 20 via the reversing valve 50. A heating device (not shown) for keeping or heating the molten resin supplied to the internal space may be provided on the cylinder wall constituting the injection cylinder 20.

[0050] The second injection component 22 is formed as a solid rod component and is configured as a plunger that is provided in the internal space of the injection cylinder 20 so as to be able to move forward and backward. The axis of the second injection component 22 is coaxial with the axis of the injection cylinder 20. The outer peripheral surface of the second injection component 22 is a smooth curved surface, and its outer diameter is set to be the same as or slightly smaller than the inner diameter of the injection cylinder 20. Thus, the second injection component 22 can move forward and backward (slide) relative to the injection cylinder 20. The second injection component 22 moves the molding material supplied to the internal space of the injection cylinder 20 as it moves forward and backward.

[0051] The second injection member driving 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 driving unit 15, the second injection member driving unit 25 also includes an advance / retract motor 26, an encoder 27, and a pressure detector 28.

[0052] The advance / retract motor 26 advances / retracts the second injection component 22 along the axis of the injection cylinder 20. A motion conversion mechanism is provided between the second injection component 22 and the advance / retract motor 26 to convert the rotational motion of the advance / retract motor 26 into the linear motion of the second injection component 22. The motion conversion mechanism can be, for example, a ball screw.

[0053] The encoder 27 detects the rotation of the forward / retract motor 26 and sends the detection signal to the control unit 80. The control unit 80 calculates the position and moving 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 the calculation results.

[0054] The pressure detection unit 28 is provided on the transmission path between the advance / retract motor 26 and the second injection component 22, detects the force transmitted between the advance / retract motor 26 and the second injection component 22, and sends its detection signal to the control unit 80. The control unit 80 calculates the pressure of the second injection component 22 based on the detected force, and adjusts or monitors the pressure received by the second injection component 22 from the molding material (back pressure on the second injection component 22), the pressure acting on the molding material from the second injection component 22, and the like.

[0055] The connection part 35 is a component that connects the storage cylinder 10 and the switching valve 50, and allows the molten resin to flow through the internal flow path 35a. The flow path 35a of the connection part 35 is formed to be bent 90 degrees inside the block, so that the molten resin in the storage cylinder 10 can flow smoothly toward the switching valve 50.

[0056] The nozzle 40 is provided on the reversing valve 50 at a position opposite to the injection cylinder 20, and is formed as a cylindrical body connected to a flow path (such as a runner) of the mold device. The nozzle 40 allows the molten resin extruded from the injection cylinder 20 through the reversing valve 50 to flow and be injected into the mold device. The mold device forms a molded product by solidifying the molten resin filled into the cavity space from the nozzle 40.

[0057] The switching valve 50 is provided between the connection part 35, the injection cylinder 20 and the nozzle 40 to switch the flow of the molten resin. The switching valve 50 includes a valve body 51, a valve core 52 and a valve core driving part (not shown).

[0058] The valve body 51 is formed into a substantially rectangular parallelepiped and accommodates a valve core 52. The valve body 51 has a supply-side connection port 53 that communicates with the flow path of the connection portion 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 surfaces on opposite sides of the rotation center line of the valve core 52. The supply-side connection port 53 is provided, for example, on a surface in a direction orthogonal to the axis connecting the injection cylinder connection port 54 and the nozzle connection port 55.

[0059] The valve core 52 rotates inside the valve body 51, thereby switching the reversing valve 50 between the first state and the second state. In the first state, the valve core 52 connects the supply side connection port 53 with the injection cylinder connection port 54 and closes the nozzle connection port 55. In the second state, the valve core 52 connects the injection cylinder connection port 54 with the nozzle connection port 55 and closes the supply side connection port 53 (see also Figure 5 (A)). Thus, in the first state, the molten resin can be moved from the connection portion 35 toward the injection cylinder 20. In the second state, the molten resin can be moved from the injection cylinder 20 toward the nozzle 40.

[0060] The valve core driving unit switches the first state and the second state by rotating the valve core 52 in the valve body 51. In addition, the state of the valve core 52 is not limited to the first state and the second state. For example, the valve core 52 can be in a state where the supply side connection port 53, the injection cylinder connection port 54, and the nozzle connection port 55 are closed at the same time. In addition, the valve core 52 can be in a state where the supply side connection port 53 is connected to the nozzle connection port 55 and the injection cylinder connection port 54 is closed.

[0061] The functions of the control unit 80 can be implemented by any hardware, software or a combination thereof. For example, the control unit 80 can apply a computer having a processor, memory, input / output interface and communication interface (not shown). The processor is a processor that combines one or more of a CPU (central processing unit), a GPU (graphics processing unit), an ASIC (application-specific integrated circuit), an FPGA (field programmable gate array), a circuit formed by a plurality of discrete semiconductors, etc., and executes and processes programs stored in the memory. The memory includes a main storage device formed by a semiconductor memory, etc., and an auxiliary storage device formed by a disk, a semiconductor memory (flash memory), etc.

[0062] The control unit 80 controls the operation of each structure of the injection device 3 (the first injection component driving unit 15, the second injection component driving unit 25, the switching valve 50, etc.) according to various instructions of the controller 4 that controls the entire injection molding machine system S. In addition, 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 (that is, directly controls the injection device 3).

[0063] The control unit 80 reads and executes the program in the memory through the processor, thereby constructing the first injection component control unit 81, the second injection component control unit 82 and the flow path switching processing unit 83 inside. The first injection component control unit 81 controls the operation of the first injection component 12. The second injection component control unit 82 controls the operation of the second injection component 22. The flow path switching processing unit 83 switches the flow direction of the molten resin by controlling each state of the reversing valve 50.

[0064] <Operation of the injection device 3>

[0065] Next, use Figure 4 The operation of the injection device 3 of the injection molding machine 1 will be described. Figure 4 1 is a flowchart showing the operation of the injection device 3 in the injection molding machine 1. The injection device 3 performs the following operations in sequence under the control of the control unit 80: Figure 4 The reservoir storing step (step S101), the measuring step (step S102), the filling step (step S103) and the pressure maintaining step (step S104) are shown, and these steps are repeated.

[0066] In the reservoir storing process, the injection device 3 accumulates a predetermined amount of molten resin in front of the internal space of the storage cylinder 10. Then, in the metering process, the injection device 3 discharges the molten resin from the storage cylinder 10 by advancing the first injection part 12 of the storage cylinder 10, and accumulates a predetermined amount of molten resin in front of the internal space of the injection cylinder 20. In the filling process, the injection device 3 advances the second injection part 22, thereby filling the molten resin accumulated in the injection cylinder 20 into the cavity space in the mold device through the nozzle 40. In the pressure holding process, the injection device 3 maintains the pressure (holding pressure) of the molten resin in front of the second injection part 22 at a set pressure, and extrude the molten resin remaining in the injection cylinder 20 toward the mold device. In addition, the injection molding machine 1 starts the cooling process after the pressure holding process to solidify the molding material in the cavity space. In addition, for the purpose of shortening the molding cycle time, the injection molding machine 1 may also implement the reservoir storing process during the execution of the injection process (filling process, pressure holding process) of the previous molding cycle. In addition, the injection molding machine 1 may also perform the metering process in the cooling process.

[0067] Below, reference Figure 5Specific operations in each process will be described. Figure 5 (A) is a cross-sectional view showing the operation of the reservoir storing process of the reservoir cylinder 10 and the injection process of the injection cylinder 20 . Figure 5 (B) is a diagram showing the operation of the metering process of the injection cylinder 20 .

[0068] In the storage process, such as Figure 5 As shown in (A), the flow path switching processing unit 83 of the control unit 80 sets the valve core 52 of the reversing valve 50 to the second state. The reason is that, as described above, in the reservoir storage process, in order to perform the injection process (filling process, pressure holding process) on the injection cylinder 20 side, it is necessary to connect the injection cylinder 20 with the nozzle 40.

[0069] In the reservoir storage process, the molten resin is pressure-fed from the molten resin supply device 6 through the molten resin supply path 7, so that the molten resin flows into the base end side of the internal space of the storage cylinder 10 through the supply connector 30. The molten resin that has flowed into the storage cylinder 10 receives the pressure-fed force of the molten resin from the molten resin supply device 6, and thus moves to the front side through the internal space of the storage cylinder 10 (around the first injection part 12). Since the flow path of the connection part 35 is closed by the valve core 52 of the reversing valve 50, the molten resin that has moved to the front side of the internal space of the storage cylinder 10 is prevented from flowing out of the storage cylinder 10.

[0070] The first injection component 12 of the storage cylinder 10 is pushed by the molten resin moving toward the front side of the internal space, thereby retreating relatively to the storage cylinder 10. Alternatively, the first injection component control unit 81 of the injection device 3 may control the advance / retract motor 16 to retreat the first injection component 12 according to the pressure of the molten resin pressure-fed from the molten resin supply device 6 during the storage process of the storage device. For example, the first injection component control unit 81 may adjust the retreat speed of the first injection component 12 so that the pressure of the molten resin detected by the pressure detection unit 18 is consistent with the target pressure.

[0071] In the reservoir storage process, when the target amount of molten resin is accumulated on the front side of the internal space of the storage cylinder 10, the control unit 80 ends the reservoir storage process and starts the metering process ( Figure 4 At this time, the flow path switching processing unit 83 of the control unit 80 controls the valve core driving unit of the reversing valve 50, such as Figure 5 As shown in (B) of FIG. 1 , the valve element 52 is brought into the first state. That is, the flow path of the connection portion 35 and the internal space of the injection cylinder 20 are brought into communication via the switching valve 50 , and molten resin can be supplied from the connection portion 35 to the injection cylinder 20 .

[0072] Furthermore, in the metering process, the first injection component control unit 81 of the control unit 80 drives the advance / retract motor 16 to advance the first injection component 12. At this time, the first injection component control unit 81 calculates the position or moving speed of the first injection component 12 based on the detection value of the encoder 17, and controls the moving speed of the first injection component 12. The first injection component 12 squeezes out the molten resin in the internal space of the storage cylinder 10 through the backflow prevention component 125, and discharges it from the front end of the storage cylinder 10. The molten resin squeezed out from the storage cylinder 10 flows smoothly in the connecting portion 35, and flows into the internal space of the injection cylinder 20 through the reversing valve 50. As a result, in the internal space of the injection cylinder 20, the molten resin is gradually accumulated in front of the second injection component 22.

[0073] In addition, the control unit 80 of the injection device 3 can cause the second injection unit 22 to retreat by driving the advance / retract motor 26 through the second injection unit control unit 82 in response to the advance of the first injection unit 12 during the metering process. That is, when the molten resin extruded from the storage cylinder 10 flows into the injection cylinder 20, the second injection unit 22 retreats in the injection cylinder 20 by the driving force of the advance / retract motor 26. As a result, the pressure of the molten resin in the injection cylinder 20 is reduced compared to the case where the molten resin pushes the second injection unit 22 to retreat the second injection unit 22.

[0074] After the above-mentioned measuring process, the control unit 80 starts the filling process (step S103). Figure 5 In (A), the flow path switching processing unit 83 of the control unit 80 controls the valve core driving unit of the switching valve 50 to make the valve core 52 enter the second state. That is, the internal space of the injection cylinder 20 and the flow path of the nozzle 40 are connected through the switching valve 50, and the flow path of the connecting part 35 is blocked.

[0075] Furthermore, in the filling process, the second injection component control unit 82 of the control unit 80 drives the advance / retract motor 26 to advance the second injection component 22 to a predetermined position. At this time, the second injection component control unit 82 calculates the position or moving speed of the second injection component 22 based on the detection value of the encoder 27, and controls the moving speed of the second injection component 22. The second injection component 22 discharges the molten resin accumulated in front of the second injection component 22 in the internal space of the injection cylinder 20 from the injection cylinder 20. The molten resin of the injection cylinder 20 moves to the nozzle 40 via the reversing valve 50, flows in the flow path of the nozzle 40, and is filled into the cavity space in the mold device.

[0076] After the filling process, the control unit 80 starts the pressure holding process (step S104). At this time, the second injection unit control unit 82 of the control unit 80 controls the rotation of the advance and retreat motor 26 according to the detection value of the pressure detection unit 28 to advance the second injection unit 22 so as to maintain the pressure (maintaining pressure) of the molten resin extruded by the second injection unit 22 at the set pressure. By advancing the second injection unit 22, the second injection unit 22 can extrude the molten resin remaining in the internal space of the injection cylinder 20 toward the mold device.

[0077] As described above, the injection molding machine 1 performs the reservoir storage process, metering process, filling process and pressure holding process in the injection device 3, while the mold clamping device 2, the ejection device and the moving device are linked, thereby being able to repeatedly manufacture molded products. In addition, the injection molding machine 1 can inject the molten resin with suppressed degradation by a simple structure of pressure-feeding the molten resin from the base end side in the storage cylinder 10 and accumulating the molten resin. That is, the flow of the molten resin in the storage cylinder 10 is in one direction, which can suppress the retention of the molten resin, thereby avoiding the degradation of the molten resin caused by the retention. As a result, the quality of the injected molten resin is high, and the quality of the molded product can be improved.

[0078] Furthermore, the first injection component 12 is provided with a backflow prevention assembly 125 (screw head 122, backflow prevention ring 123, seal ring 124), which can prevent the molten resin from flowing back when the first injection component 12 moves forward. Therefore, the first injection component 12 can discharge the molten resin to the injection cylinder 20 with high precision. Furthermore, the injection molding machine 1 does not need to be provided with a valve or the like for preventing backflow.

[0079] Moreover, since the first injection component 12 has a shaft body 121 without uneven curved surfaces, it is possible to eliminate kneading of the molten resin, etc., and suppress the influence of kneading on the molten resin. In addition, since there is no scraper, the structure of the first injection component 12 becomes simple, which can reduce the manufacturing cost. In particular, since the recycled resin is prone to deterioration, the retention is suppressed by squeezing the molten resin, and the shearing by the scraper is eliminated, thereby greatly suppressing the degradation of the recycled resin. In addition, the molding material injected by the injection molding machine 1 is not limited to the recycled resin, and various materials can also be applied. In this case, the first injection component 12 can also suppress the degradation caused by the conveying load of the screw. However, the first injection component 12 is applied to the injection device 3 that conveys the molten molten resin instead of the solid resin, thereby achieving a significant effect in suppressing the degradation of the molten resin.

[0080] In addition, the injection molding machine 1 of the present invention is not limited to the above-mentioned embodiment, and various modifications can be adopted. For example, in the injection molding machine 1, the first injection component 12 applied to the storage cylinder 10 is not limited to a screw without the above-mentioned scraper, and various structures can be applied. Figure 3 (B) and Figure 3 (C) provides some explanation.

[0081] like Figure 3 As shown in (B), the first injection component 12A involved in the first modification is different from the first injection component 12 in that it has a spiral scraper 126 formed to protrude relatively low on the outer peripheral surface of the shaft body 121. That is, in the above-mentioned embodiment, since the molten resin is pressed by the molten resin supply device 6, it is configured to be without a scraper, but it may also have a scraper 126 that can assist in conveying the molten resin while suppressing the degradation of the molten resin. At this time, the first injection component 12A is configured to rotate around the axis in the storage cylinder 10.

[0082] For example, the scraper 126 of the first injection part 12 is appropriately designed to have a smaller outer diameter (lower height), a wider pitch, and a smaller number and ratio of blades than a general screw scraper that moves the molding material while melting and kneading the molding material. Figure 3 (B) shows an example in which the outer diameter of the scraper 126 is smaller. For example, the outer diameter of the scraper 126 is set smaller than the outer diameter of the backflow prevention ring 123.

[0083] Furthermore, when the scraper 126 is provided, it is preferable that the length L of the portion where the scraper 126 is provided is shortened relative to the total length of the screw. For example, when the inner diameter of the storage cylinder 10 is set to D and the length of the scraper 126 is set to L, it is preferable to set the length L of the scraper 126 so that L / D≤15. By shortening the length L of the scraper 126 in the shaft body 121, the range in which the scraper 126 affects the molten resin can be reduced, and as a result, the degradation of the molten resin can be suppressed. Moreover, the first injection component 12 having the scraper 126 can smoothly move the molten resin that is pressed into the storage cylinder 10 to the front side. Regardless of the size of the outer diameter of the scraper 126, whether the outer diameter of the scraper 126 is the same as the inner diameter D of the storage cylinder 10 or smaller (for example, less than half of the interval between the shaft body 121 and the inner circumferential surface of the storage cylinder 10), it is preferable that the length L of the scraper 126 is not too long compared with the inner diameter D of the storage cylinder 10. However, even if the unevenness is provided in a spiral shape and has a height of 5% or less of the distance between the shaft body 121 and the inner peripheral surface of the storage cylinder 10 and does not promote the degradation of the molten resin, it is considered to be a scraper as mentioned herein.

[0084] like Figure 3 As shown in (C), the first injection component 12B involved in the second modification is different from the first injection components 12 and 12A in that the front end of the shaft body 121 does not include the backflow prevention component 125. As described above, in the storage cylinder 10, the molten resin is continuously pressed from the molten resin supply path 7. Therefore, even if the first injection component 12B without the backflow prevention component 125 is used and the first injection component 12B is extruded after the storage process in the reservoir, the molten resin can be suppressed from flowing back to the base end side and the molten resin can be discharged from the front end of the storage cylinder 10.

[0085] <Structure and Operation of Injection Device 3A According to Second Embodiment>

[0086] Figure 6 1 is a cross-sectional view schematically showing an injection device 3A of an injection molding machine 1A according to a second embodiment. The injection molding machine 1A according to the second embodiment is different from the injection molding machine 1 according to the first embodiment in that it includes one injection cylinder 20 and one injection component 23, and that molten resin is pressure-fed to the injection cylinder 20 from a position further back than the front end of the injection component 23. Thus, even when the injection molding machine 1A uses one injection cylinder 20, the molten resin can be well accumulated on the front side of the internal space of the injection cylinder 20 (the front side of the injection component 23) by pressure-feeding the molten resin from the base end side of the injection cylinder 20.

[0087] A connection portion 36 for connecting to the nozzle 40 without a valve core is provided at the front end of the injection cylinder 20. The injection member 23 can be configured similarly to the first injection member 12, 12A, 12B according to the first embodiment. Figure 6 2 shows an example in which the shaft body 121 is not provided with a scraper but has a backflow prevention member 125 .

[0088] In the metering process of accumulating the molten resin in the injection cylinder 20, the injection molding machine 1A moves the molten resin pumped forward in the injection cylinder 20, similarly to the above-mentioned reservoir storage process. In addition, in the injection process (filling process, pressure holding process), the injection molding machine 1A can inject the molten resin accumulated in the front into the mold device by advancing the injection part 23.

[0089] The injection molding machines 1 and 1A involved in the embodiments disclosed this time are illustrative in all aspects and are not restrictive. The embodiments can be modified and improved in various ways without departing from the scope and gist of the attached technical solutions. The matters recorded in the above-mentioned various embodiments can adopt other structures within the scope of non-contradiction, and can be combined within the scope of non-contradiction.

Claims

1. An injection molding machine, comprising: Cylinder body; An injection component is accommodated inside the cylinder; and A molten resin supply device is connected to the cylinder and pressure-feeds the molten resin from a position closer to the base end than the front end of the injection component. In the cylinder, the molten resin is moved to a position forward of the injection component by using the pressure-feeding force of the molten resin supply device, and the molten resin is accumulated in front of the internal space of the cylinder. The molten resin is injected from the front end of the cylinder by the advancement of the injection member.

2. The injection molding machine according to claim 1, wherein: The cylinder includes: 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.

3. The injection molding machine according to claim 2, wherein: The first cylinder has the injection component inside. The second cylinder includes a second cylinder side injection member, and the molten resin supplied from the first cylinder flows into the second cylinder from the front end thereof, and the second cylinder side injection member retreats. The molten resin is injected into the mold device from the front end of the second cylinder by the second cylinder-side injection member moving forward.

4. The injection molding machine according to claim 3, wherein: A control unit for controlling the injection unit and the second cylinder side injection unit is provided. The control unit controls the following processes: an accumulator storing step of pressure-feeding the molten resin in the internal space of the first cylinder to store the molten resin in front of the internal space of the first cylinder; a metering step of, after the reservoir storing step, advancing the injection member to discharge the molten resin from the first cylinder and accumulating the molten resin in front of the internal space of the second cylinder; and an injection step, 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 during the injecting step.

5. The injection molding machine according to any one of claims 1 to 4, wherein: The injection member includes a backflow prevention member at a front end thereof, the backflow prevention member preventing the molten resin from flowing back toward a base end while extruding the molten resin in front.

6. The injection molding machine according to any one of claims 1 to 4, wherein: The injection component has a shaft body extending in the axial direction of the cylinder. The outer peripheral surface of the shaft body is formed into a curved surface without irregularities.

7. The injection molding machine according to any one of claims 1 to 4, wherein: The injection component has a shaft body extending in the axial direction of the cylinder. A spiral scraper is protrudingly formed on the outer peripheral surface of the shaft body.

8. The injection molding machine according to any one of claims 1 to 4, wherein: The molten resin supply device melts the recovered resin and supplies the melted resin to the cylinder.

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