Injection molding machine and injection device

Abstract

To simplify a configuration of a hydraulic system.SOLUTION: In a hydraulic system 28A, a B port 50 and a C port 70 are connected. Accordingly, even if a solenoid valve 38 and a flow adjustment valve 39 are deleted, hydraulic oil supplied to the B port 50 can also be supplied to the C port 70. As a result, the hydraulic oil supplied to the C port 70 can be brought into contact with a side surface of a piston 27 to apply a retraction pressure to the side surface of the piston 27. Therefore, according to the hydraulic system 28A, a retraction action of the piston 27 can be realized even while the solenoid valve 38 and the flow adjustment valve 39 are deleted.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to an injection molding machine and an injection device, and more particularly to a technology effective when applied to, for example, an injection molding machine and an injection device equipped with a hydraulic device.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2007-216285 (Patent Document 1) describes a technology related to an injection molding machine capable of rapidly decelerating the speed of an injection piston and shifting from an injection process to a holding pressure process without using a servo control valve that complicates a hydraulic circuit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An injection molding machine is a device that manufactures molded products by kneading and melting materials and then pouring them into a mold, and is a device capable of processing a series of injection molding processes such as melting of materials, pouring into a mold (injection), cooling, and taking out. This injection molding machine is composed of an injection device that performs the injection operation of the material and a mold clamping device that molds the material injected from the injection device.

[0005] In this regard, the inventor of the present invention focuses on an injection device that performs the injection operation of the material among injection molding machines. In the injection device, the injection operation of the material is performed by using a hydraulic device, and it is desired to simplify the configuration of the hydraulic device. That is, in order to reduce the manufacturing cost in the injection molding machine and improve the reliability of the injection molding machine by simplifying the configuration of the hydraulic device, a device for simplifying the configuration of the hydraulic device is desired.

Means for Solving the Problems

[0006] An injection molding machine in one embodiment comprises an injection device that performs a material injection operation, and a clamping device that molds the material injected from the injection device. The injection device includes a screw, a piston connected to the screw, and a hydraulic unit that drives the piston in the axial direction. The hydraulic unit includes a first port that serves as a supply path for hydraulic fluid when the piston moves forward, a second port that serves as a discharge path for hydraulic fluid when the piston moves forward, and a third port that serves as a discharge path for hydraulic fluid when the second port is blocked by the piston when the piston moves forward. The second and third ports are connected to each other so that when the piston moves backward, hydraulic fluid is supplied to the second port, and when hydraulic fluid is discharged from the first port, hydraulic fluid is also supplied to the third port, and the hydraulic fluid supplied to the third port enables the piston to move backward.

[0007] In one embodiment, the injection device includes a screw, a piston connected to the screw, and a hydraulic unit that drives the piston in the axial direction. The hydraulic unit has a first port that serves as a supply path for hydraulic fluid when the piston moves forward, a second port that serves as a discharge path for hydraulic fluid when the piston moves forward, and a third port that serves as a discharge path for hydraulic fluid when the second port is blocked by the piston when the piston moves forward. The second and third ports are connected to each other so that when the piston moves backward, hydraulic fluid is supplied to the second port, and when hydraulic fluid is discharged from the first port, hydraulic fluid is also supplied to the third port, and the hydraulic fluid supplied to the third port enables the piston to move backward. [Effects of the Invention]

[0008] According to one embodiment, the configuration of the hydraulic system can be simplified. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing the configuration of an injection molding machine. [Figure 2]This diagram shows the configuration of a hydraulic system in related technologies. [Figure 3] This is a diagram illustrating the "injection operation" in related technologies. [Figure 4] This is a schematic plan view illustrating an example of the planar shapes of ports A, B, and C provided on a hydraulic component in related technologies. [Figure 5] This diagram illustrates the retraction motion of a piston in related technologies. [Figure 6] This diagram illustrates the potential for improvement in related technologies. [Figure 7] This is a diagram showing the configuration of the hydraulic system in its implemented form. [Figure 8] This is a schematic plan view showing an example of the planar shapes of ports A, B, and C provided on a hydraulic member in an actual embodiment. [Figure 9] This is a diagram illustrating the "injection operation" in the materialization mode. [Figure 10] This diagram illustrates the retraction motion of a piston in an actualized form. [Modes for carrying out the invention]

[0010] In all the drawings illustrating the embodiments, the same reference numeral is used for identical components, and repeated explanations of them are omitted. Hatching may be used even in plan views to improve clarity.

[0011] <Configuration of an injection molding machine> The technical concept in this embodiment can be broadly applied to injection molding machines equipped with an injection device and a clamping device. In this regard, the technical concept in this embodiment will be explained below using an injection molding machine in which one injection device is provided for one clamping device as an example. However, the technical concept in this embodiment is not limited to this and can be broadly applied to, for example, a "multi-injection molding machine" in which multiple injection devices are provided for one clamping device.

[0012] <<Overview of Injection Molding Machine>> FIG. 1 is a schematic diagram showing the configuration of an injection molding machine 100.

[0013] In FIG. 1, the injection molding machine 100 has a clamping device 1 and an injection device 2. Here, the clamping device 1 is a device that performs a clamping operation. For example, the clamping device 1 is configured to be able to mount a mold into which the material injected from the injection device 2 flows, and by performing a clamping operation on the mold, it is a device that manufactures a molded product by flowing the material into the cavity (sealed space) formed. On the other hand, the injection device 2 is a device that performs an injection operation. For example, it kneads and melts the material and injects the kneaded and melted material into the cavity formed by the clamping device 1.

[0014] <<Configuration of Clamping Device>> As shown in FIG. 1, the clamping device 1 has a movable platen 11 that can move and a fixed platen 10 that is fixed, and is configured such that the distance between the movable platen 11 and the fixed platen 10 can be variably controlled. And between the movable platen 11 and the fixed platen 10, a movable mold (mold) 13 and a fixed mold (mold) 12 can be arranged. Thus, for example, by the clamping device 1 variably controlling the distance between the movable platen 11 and the fixed platen 10, the distance between the movable mold 13 and the fixed mold 12 can be brought closer to "close the mold" and the distance between the movable mold 13 and the fixed mold 12 can be increased to "open the mold". At this time, when "closing the mold" between the movable mold 13 and the fixed mold 12, a sealed space (cavity) CAV is formed between the movable mold 13 and the fixed mold 12, and by flowing the material into this sealed space CAV, a molded product is formed. In particular, in the injection molding machine 100 shown in FIG. 1, when "closing the mold" between the movable mold 13 and the fixed mold 12, one sealed space CAV is formed, and a molded product is formed by flowing the material into this sealed space CAV. In this way, the clamping device 1 is configured.

[0015] <<Configuration of Injection Device>> Next, as shown in FIG. 1, an injection device 2 for extruding a material is connected to the mold clamping device 1, and the material extruded from the injection device 2 flows into a sealed space CAV formed by "closing the mold" between the movable mold 13 and the fixed mold 12.

[0016] This injection device 2 has a hopper 21 for containing a material (raw material) and a cylinder 22. When the material is put into the hopper 21, the material is kneaded by a rotatable screw 23 disposed inside the cylinder 22. Specifically, the screw 23 is connected to a screw rotation motor 24, and by driving the screw rotation motor 24, the screw 23 is configured to rotate.

[0017] At this time, a heater 25 is disposed around the cylinder 22, and the material put into the cylinder 22 is kneaded by the screw 23 while being heated by the heater 25 to become a molten material. A nozzle 26 is provided at the tip of the cylinder 22. Further, a piston 27 is connected to the screw 23, and the forward and backward movements of this piston 27 are controlled by a hydraulic device 28. Thereby, for example, when the hydraulic device 28 is controlled to advance the piston 27, as a result, the screw 23 connected to the piston 27 advances, and the molten material extruded by the advancing screw 23 is ejected from the nozzle 26. In this way, the injection device 2 is configured.

[0018] For example, as the material (molten material) ejected from the injection device 2, a metal material is assumed. Specifically, the material ejected from the injection device 2 is assumed to be a magnesium alloy. In this case, since the molten material made of the magnesium alloy is likely to solidify, it is necessary to increase the ejection speed ejected from the injection device 2. For this reason, in the injection device 2, the injection operation is configured to be performed using the hydraulic device 28. However, the material ejected from the injection device 2 is not limited to a metal material, and resins (plastics) etc. can also be used.

[0019] <Operation of the injection molding machine> The injection molding machine 100 is configured as described above, and its operation will be explained below.

[0020] First, in Figure 1, if the material to be injected is a metal, a release agent is sprayed onto the cavity surfaces of the open movable mold 13 and the fixed mold 12. Then, the movable platen 11 of the clamping device 1 is moved. This brings the movable mold 13 into contact with the fixed mold 12, thus "closing" the mold. After that, the hydraulic device 28 controls the piston 27 to move forward. This causes the screw 23 connected to the piston 27 to move to the left, i.e., forward. As a result, the molten material, which has been accumulated in a predetermined amount between the nozzle 26 and the screw 23 by the metering process described later, is injected from the tip of the nozzle 26 into the sealed space CAV (cavity) between the "closed" movable mold 13 and the fixed mold 12. In other words, the metered molten material is injected from the nozzle 26 into the sealed space CAV (injection process).

[0021] Next, after the injection is complete, pressure is applied to the material in the sealed space CAV through the molten material remaining in the cylinder 22 to compensate for the shrinkage of the material that occurs as the molten material cools. In other words, after the molten material is injected, the screw 23 maintains pressure in the sealed space CAV. This state is called the "holding pressure state," and while this holding pressure state is maintained, the molten material is cooled by the movable mold 13 and fixed mold 12, which are controlled to a temperature below the solidification temperature of the molten material (holding pressure process). Specifically, the molten material filling the sealed space CAV is cooled by the movable mold 13 and fixed mold 12 to a temperature below the solidification temperature of the molten material.

[0022] Next, in Figure 1, solid material is fed from the hopper 21 into the cylinder 22. Then, the screw 23 is rotated by the screw rotation drive mechanism 24, and at the same time, the piston 27 is moved backward by the hydraulic device 28, thereby moving the screw 23, which is connected to the piston 27, backward by a predetermined amount. During this time, the rotational drive of the screw 23 causes the material supplied from the hopper 21 to melt in the cylinder 22 of the injection device 2 and move forward. That is, the material supplied from the hopper 21 is heated and melted by the heat from the heater 25 and the shear heat generated by the rotation of the screw 23, becoming molten material and moving forward. As a result, a predetermined amount of molten material accumulates between the nozzle 26 and the screw 23 (metering process).

[0023] Subsequently, the mold clamping device 1 is operated to "open the mold" between the movable mold 13 and the fixed mold 12. After "opening" the mold between the movable mold 13 and the fixed mold 12 in this way, the molded product is ejected by the ejector device provided in the mold clamping device 1 using ejector pins. This allows the molded product to be removed from the mold clamping device 1. This molded product is a product molded by the injection molding machine 100.

[0024] By repeating this series of operations, it is possible to continuously manufacture molded products of the same shape. In this way, by repeatedly operating the injection molding machine 100, it is possible to mass-produce molded products.

[0025] <Considerations by the inventors> The inventors have been studying the injection molding machine 100 having the above-described configuration. Specifically, the inventors have been studying the simplification of the hydraulic system 28 provided in the injection device 2 from the viewpoint of reducing the manufacturing cost or improving the reliability of the injection molding machine 100. As a result, it has become clear that the current hydraulic system 28 provided in the injection device 2 needs to be considered for improvement from the viewpoint of reducing the manufacturing cost or improving the reliability of the injection molding machine 100. Therefore, in the injection molding machine 100, it is desirable to devise ways to simplify the hydraulic system 28 provided in the injection device 2. Below, first, the hydraulic system 28R in related technologies will be described. Then, the room for improvement that exists in the hydraulic system 28R in related technologies will be described. After that, the hydraulic system 28A in this embodiment, which incorporates improvements that address the room for improvement that exists in related technologies, will be described.

[0026] <Explanation of related technologies> In this specification, "related technology" refers to technology that is not publicly known but has a problem identified by the present inventor, and is a technology that forms the basis of the technical idea in this embodiment.

[0027] Figure 2 shows the configuration of the hydraulic system 28R in the related technology.

[0028] In Figure 2, the hydraulic member into which the piston 27 is inserted is provided with ports A 40, B 50, and C 60, which serve as passages for the hydraulic fluid.

[0029] On the other hand, the configuration related to port A 40 includes a hydraulic system 28R which has a pump 30, an accumulator 31, a servo valve 32, a solenoid valve 33a, and a tank 33. Port A 40 is connected to the tank 33 via the solenoid valve 33a and also to the accumulator 31 via the servo valve 32. The accumulator 31 is connected to the pump 30.

[0030] Here, the pump 30 has the function of sending hydraulic fluid into the flow path, and the accumulator 31 has the function of storing hydraulic fluid. In addition, the servo valve 32 has the function of adjusting the flow rate of hydraulic fluid, and the tank 33 has the function of storing hydraulic fluid.

[0031] Next, regarding the configuration related to port B 50, the hydraulic system 28R includes a pump 30, a solenoid valve 34, a logic valve 35, an accumulator 36, and a tank 37. Port B 50 is connected to the pump 30 via the solenoid valve 34, and to the accumulator 36 and tank 37 via the logic valve 35.

[0032] Here, the pump 30 has the function of sending hydraulic fluid into the flow path, and the solenoid valve 34 has an opening and closing mechanism. In addition, the logic valve 35 has the function of opening and closing the flow path, and the accumulator 36 and tank 37 have the function of storing hydraulic fluid.

[0033] Next, regarding the configuration related to port C 60, the hydraulic system 28R has a pump 30, a solenoid valve 34, a solenoid valve 38, and a flow control valve 39. Port C 60 is connected to the pump 30 via the solenoid valves 34, 38, and 39.

[0034] Here, the pump 30 has the function of sending hydraulic fluid into the flow path, and the solenoid valves 34 and 38 have opening and closing mechanisms. In addition, the flow control valve 39 has the function of adjusting the flow rate of the hydraulic fluid. In this way, the hydraulic system 28R in the related technology is configured.

[0035] <<Explanation of "Injection Operation">> Next, we will explain the "injection operation" using the hydraulic system 28R.

[0036] In Figure 2, initially, solenoid valves 33a, 34, and 38 are in a closed state. Then, by operating the pump 30 in this state, hydraulic fluid is sent from the pump 30 to the accumulator 31, resulting in the accumulation of hydraulic fluid in the accumulator 31. Subsequently, the hydraulic fluid accumulated in the accumulator 31 is released all at once. As a result, the flow rate of the hydraulic fluid released from the accumulator 31 is adjusted by the servo valve 32, and then the hydraulic fluid with the adjusted flow rate by the servo valve 32 is supplied to port A 40.

[0037] When hydraulic fluid is supplied to port A 40, the pressure of the hydraulic fluid causes the piston 27 to move in the forward direction. At this time, the hydraulic fluid pushed out by the forward-moving piston 27 enters port B 50. The hydraulic fluid that has entered port B 50 is then discharged from port B 50 by opening the logic valve 35 and flows into the accumulator 36 and tank 37. In this way, by supplying hydraulic fluid to port A 40 and discharging it from port B 50, the piston 27 moves in the forward direction. Note that since the solenoid valve 38 is closed, no hydraulic fluid is discharged from port C 60.

[0038] Subsequently, as the piston 27 moves forward, it will block port B 50, as shown in Figure 3. In this case, the discharge of hydraulic fluid from port B 50 will cease, and the forward movement of the piston 27 will be suppressed. That is, when the piston 27 moves to a position where it blocks port B 50, the piston 27 will decelerate rapidly. When this deceleration occurs, hydraulic fluid will no longer be discharged from port B 50, but by opening solenoid valves 34 and 38, hydraulic fluid will be discharged from port C 60, as shown in Figure 3.

[0039] As described above, according to the related technology, the control unit provided in the injection molding machine 100 controls the hydraulic device 28R, thereby enabling the "injection operation" in which the piston 27 is moved in the forward direction and then rapidly decelerated.

[0040] Figure 4 is a schematic plan view illustrating an example of the planar shapes of ports A 40, B 50, and C 60 provided on a hydraulic member in the related technology. As shown in Figure 4, the planar shapes of ports A 40 and B 50 are, for example, rectangular. On the other hand, port C 60 is circular. Furthermore, the planar size of port C 60 is smaller than the planar sizes of ports A 40 and B 50. In this way, the planar shapes of ports A 40, B 50, and C 60 are configured.

[0041] <<The necessity of piston retraction>> As described above, during the "injection operation," the piston 27 moves forward. In contrast, in the "metering process," for example, after performing the "injection operation," the molten material supplied from the hopper 21 is sent forward while the screw 23 is retracted backward in preparation for the next "injection operation." In this process, the piston 27 connected to the screw 23 needs to be moved backward. That is, the hydraulic system 28R needs to be configured not only to move the piston 27 forward, but also to move the piston 27 backward. Furthermore, the retraction of the piston 27 is required not only during the "metering operation" described above, but also during the so-called "suck-back operation."

[0042] Here, "suck-back operation" refers to the action of retracting the piston 27 to prevent drooling (drip of material from the nozzle 26) after the injection operation. From this, it can be seen that, for example, the piston 27 needs to be retracted during "metering operation" and "suck-back operation".

[0043] <<Explanation of piston retraction>> Therefore, the retraction operation of the piston 27 using the hydraulic device 28R will be explained.

[0044] Figure 5 illustrates the retraction operation of a piston 27 using a hydraulic system 28R in the related technology. In Figure 5, the pump 30 is operated with solenoid valves 34 and 38 open. As a result, the hydraulic fluid sent from the pump 30 passes through the open solenoid valves 34 and 38, has its flow rate adjusted by the flow control valve 39, and is supplied to port C 60. The hydraulic fluid supplied to port C 60 applies pressure to the side of the piston 27, causing the piston 27 to move in the retraction direction. At this time, the hydraulic fluid pushed out by the retracting piston 27 enters port A 40. The hydraulic fluid that has entered port A 40 is then discharged from port A 40 by opening solenoid valve 33a with the servo valve 32 closed, and flows into tank 33. In this way, by supplying hydraulic fluid to port B 50 and discharging hydraulic fluid from port A 40, the piston 27 moves in the retraction direction.

[0045] <Room for improvement> As described above, the hydraulic system 28R in the related technology allows the piston 27 to be moved backward. In this regard, the inventors are considering simplifying the hydraulic system 28R in the related technology in order to reduce manufacturing costs and improve the reliability of the injection molding machine 100 by simplifying the configuration of the hydraulic system 28R. In doing so, the inventors have newly discovered that there is room for improvement in which it becomes difficult to realize the backward movement of the piston 27 when the configuration of the hydraulic system 28R in the related technology is simplified.

[0046] The following describes the potential for improvement in related technologies that arise from simplifying the configuration of the hydraulic system 28R.

[0047] Figure 6 illustrates the room for improvement in the related technology.

[0048] As shown in Figure 6, the inventors are considering simplifying the configuration of the hydraulic system 28R by, for example, removing the solenoid valve 38 and the flow control valve 39. In this case, as shown in Figure 6, when the pump 30 is operated with the solenoid valve 34 open, the hydraulic fluid sent from the pump 30 flows through the open solenoid valve 34 into port B 50.

[0049] In this case, after the rapid deceleration of the piston 27, the B port 50 is blocked by the piston 27. Therefore, the hydraulic fluid supplied to the B port 50 cannot come into contact with the side surface of the piston 27. As a result, the hydraulic fluid supplied to the B port 50 cannot move the piston 27 in the backward direction.

[0050] As described above, if the solenoid valve 38 and the flow control valve 39 are removed, the hydraulic fluid will not be supplied to port C 60 but to port B 50. However, the hydraulic fluid supplied to port B 50 cannot apply retraction pressure to the side of the piston 27. Therefore, in related technologies, if the solenoid valve 38 and the flow control valve 39 are removed, the piston 27 will not be able to retract. In other words, in related technologies, there is room for improvement in that if the configuration of the hydraulic system 28R is simplified by removing the solenoid valve 38 and the flow control valve 39, the piston 27 will not be able to retract. Therefore, in this embodiment, ingenuity has been taken to overcome the room for improvement present in related technologies. The technical concept of this embodiment, in which this ingenuity has been taken, will be explained below.

[0051] <Basic Concept in the Embodiment> In related technologies, the essential reason why removing the solenoid valve 38 and flow control valve 39 prevents the piston 27 from retracting is that port B 50 and port C 60 are physically separated. This is because, even if the solenoid valve 38 and flow control valve 39 are removed, if hydraulic fluid can be supplied to port C 60, the hydraulic fluid supplied to port C 60 can come into contact with the side surface of the piston 27, and as a result, the hydraulic fluid can apply retraction pressure to the side surface of the piston 27.

[0052] Therefore, taking this into consideration, in this embodiment, port B 50 and port C 60 are connected. In other words, the basic idea in this embodiment is to connect port B 50 and port C 60. According to this basic idea, even if the solenoid valve 38 and flow control valve 39 are removed, the hydraulic fluid supplied to port B 50 can also be supplied to port C 60. As a result, the hydraulic fluid supplied to port C 60 comes into contact with the side surface of the piston 27, thereby applying retraction pressure to the side surface of the piston 27. In other words, according to this basic idea, the retraction operation of the piston 27 can be achieved even while removing the solenoid valve 38 and flow control valve 39.

[0053] The following describes the manifestations of this fundamental idea.

[0054] <Method of Realization> <<Hydraulic System Configuration>> Figure 7 shows the configuration of the hydraulic system 28A in its implemented form.

[0055] In Figure 7, the hydraulic member into which the piston 27 is inserted is provided with ports A 40, B 50, and C 70, which serve as passages for the hydraulic fluid. Here, as shown in Figure 7, in the actual embodiment, ports B 50 and C 70 are connected to each other.

[0056] As a configuration related to port A 40, the hydraulic system 28R includes a pump 30, an accumulator 31, a servo valve 32, a solenoid valve 33a, and a tank 33. Port A 40 is connected to the tank 33 via the solenoid valve 33a and also to the accumulator 31 via the servo valve 32. The accumulator 31 is connected to the pump 30.

[0057] Pump 30 has the function of sending hydraulic fluid into the flow path, and accumulator 31 has the function of storing hydraulic fluid. Servo valve 32 has the function of adjusting the flow rate of hydraulic fluid, and tank 33 has the function of storing hydraulic fluid.

[0058] Next, relating to the interconnected B port 50 and C port 70, the hydraulic system 28A includes a pump 30, a solenoid valve 34, a logic valve 35, an accumulator 36, and a tank 37. The interconnected B port 50 and C port 70 are connected to the pump 30 via the solenoid valve 34, and to the accumulator 36 and tank 37 via the logic valve 35.

[0059] Pump 30 has the function of sending hydraulic fluid into the flow path, and solenoid valve 34 has an opening and closing mechanism. Logic valve 35 has the function of opening and closing the flow path, and accumulator 36 and tank 37 have the function of storing hydraulic fluid.

[0060] Furthermore, in the implemented hydraulic system 28A, the solenoid valve 38 and flow control valve 39, which were provided in the related technology, have been omitted. As a result, the configuration of the hydraulic system 28A is simplified in the implemented version. The hydraulic system 28A is configured in this manner.

[0061] Figure 8 is a schematic plan view showing an example of the planar shapes of ports A 40, B 50, and C 70 provided on a hydraulic member in a real-world embodiment. As shown in Figure 8, the planar shapes of ports A 40 and B 50 are, for example, rectangular. The planar shape of port C 70 is also square, and in plan view, port C 70 is connected to port B 50. In other words, port B 50 and port C 70 are connected to each other. That is, port B 50 and port C 70 are not separate from each other, but can be said to be integrally formed. As a result, for example, hydraulic fluid flowing into port B 50 will also flow into port C 70. Here, the planar shape of port C 70 is not limited to a square shape, but may be, for example, circular or polygonal.

[0062] Furthermore, while Figure 8 shows a configuration in which the C port 70 is connected to the center of the long side of the rectangular B port 50, the placement of the C port 70 is not limited to the center of the long side of the B port 50. For example, the C port 70 may be connected to the upper or lower part of the long side of the rectangular B port 50, or it may even be arranged so that the C port 70 is connected to the short side of the B port 50.

[0063] Furthermore, the planar size (cross-sectional area) of port C 70 is smaller than the planar size (cross-sectional area) of ports A 40 and B 50. In this way, the planar shapes of ports A 40, B 50, and C 70 are configured in the actualized embodiment.

[0064] <<Explanation of "Injection Operation">> Next, we will explain the "injection operation" using the hydraulic system 28A.

[0065] In Figure 7, initially, solenoid valves 33a and 34 are closed. Then, by operating the pump 30 in this state, hydraulic fluid is sent from the pump 30 to the accumulator 31, resulting in the accumulation of hydraulic fluid in the accumulator 31. Subsequently, the hydraulic fluid accumulated in the accumulator 31 is released all at once. As a result, the flow rate of the hydraulic fluid released from the accumulator 31 is adjusted by the servo valve 32, and then the hydraulic fluid with the adjusted flow rate by the servo valve 32 is supplied to port A 40.

[0066] When hydraulic fluid is supplied to port A 40, the pressure of the hydraulic fluid causes the piston 27 to move in the forward direction. At this time, the hydraulic fluid pushed out by the forward-moving piston 27 enters ports B 50 and C 70. The hydraulic fluid that has entered ports B 50 and C 70 is then discharged from ports B 50 and C 70 by opening the logic valve 35 and flows into the accumulator 36 and tank 37. In this way, by supplying hydraulic fluid to port A 40 and discharging it from ports B 50 and C 70, the piston 27 moves in the forward direction.

[0067] Subsequently, as the piston 27 moves forward, it will block port B 50, as shown in Figure 9. In this case, the discharge of hydraulic fluid from port B 50 will cease, and the forward movement of the piston 27 will be suppressed. That is, once the piston 27 moves to a position where it blocks port B 50, the piston 27 will decelerate rapidly.

[0068] However, in the implemented configuration, port B 50 and port C 70 are connected to each other. Therefore, even if port B 50 is blocked by the piston 27, the hydraulic fluid pushed out by the piston 27 is discharged from port C 70 and flows into the accumulator 36 and tank 37. In this implemented configuration, as a result of port B 50 and port C 70 being connected to each other, even if port B 50 is blocked by the piston 27, the hydraulic fluid is easily discharged from port C 70. This means that the deceleration of the piston 27 is influenced by the cross-sectional area (planar area) of port C 70.

[0069] In other words, if the surface area of ​​port C 70 becomes too large, even if port B 50 is blocked, hydraulic fluid can be easily discharged from port C 70, thus slowing down the deceleration of the piston 27 caused by the blocking of port B 50. Therefore, from the viewpoint of achieving a certain degree of piston deceleration, it is necessary to avoid making the surface area of ​​port C 70 too large. In other words, qualitatively, in the implemented embodiment, it can be understood that the upper limit of the surface area of ​​port C 70 is defined from the viewpoint of considering how to produce an appropriate deceleration of the piston 27.

[0070] As described above, according to the embodiment, the control unit provided in the injection molding machine 100 controls the hydraulic device 28A, thereby enabling the "injection operation" in which the piston 27 is moved in the forward direction and then rapidly decelerated.

[0071] <<Explanation of piston retraction>> Next, we will describe the retraction operation of the piston 27 using the hydraulic device 28A.

[0072] Figure 10 illustrates the retraction operation of the piston 27 using the hydraulic system 28A in an implemented embodiment. In Figure 10, the pump 30 is operated with solenoid valves 33a and 34 open. As a result, the hydraulic fluid sent from the pump 30 passes through the open solenoid valve 34 and is supplied to port B 50, as well as to port C 70 which is connected to port B 50. As a result, the hydraulic fluid supplied to port B 50 cannot come into contact with the side surface of the piston 27, and therefore cannot move the piston 27 in the retraction direction. However, in the implemented embodiment, hydraulic fluid is also supplied to port C 70 which is connected to port B 50. Therefore, in the implemented embodiment, pressure is applied to the side surface of the piston 27 by the hydraulic fluid supplied to port C 70, resulting in the piston 27 moving in the retraction direction. At this time, the hydraulic fluid pushed out by the retracting piston 27 enters port A 40. Then, the hydraulic fluid that has entered port A 40 is discharged from port A 40 by opening the solenoid valve 33a while the servo valve 32 is closed, and flows into tank 33. In this way, according to the implemented configuration, by supplying hydraulic fluid to the interconnected ports B 50 and C 70 while discharging hydraulic fluid from port A 40, the piston 27 moves in the reversing direction.

[0073] Thus, in this embodiment, when the piston 27 is moved backward, hydraulic fluid is supplied to port B 50. As a result of the connection between port B 50 and port C 70, hydraulic fluid is also supplied to port C 70. Consequently, the hydraulic fluid supplied to port C 70 applies pressure to the side of the piston 27, allowing the piston 27 to move backward. Therefore, if the cross-sectional area (planar area) of port C 70 is too small, the pressure applied to the side of the piston 27 will be small, and the backward movement of the piston 27 will be slow. For this reason, from the viewpoint of ensuring a certain backward speed of the piston 27, it is necessary not to make the planar area of ​​port C 70 too small. In other words, qualitatively, in this embodiment, it can be understood that a lower limit of the planar area of ​​port C 70 is defined from the viewpoint of ensuring an appropriate backward speed of the piston 27. From the above, in the configuration of the embodiment in which port B 50 and port C 70 are connected to each other, an upper limit of the surface area of ​​port C 70 is defined from the viewpoint of considering the appropriate deceleration of the piston 27, while a lower limit of the surface area of ​​port C 70 is defined from the viewpoint of ensuring an appropriate retraction speed of the piston 27.

[0074] To summarize the above, the injection molding machine 100 in the embodiment has the following configuration. That is, the injection molding machine 100 comprises an injection device 2 that performs the injection operation of material, and a clamping device 1 that molds the material injected from the injection device 2.

[0075] Here, the injection device 2 includes a screw 23, a piston 27 connected to the screw 23, and a hydraulic device (hydraulic unit) 28A that drives the piston 27 in the axial direction.

[0076] The hydraulic device 28A includes port A 40, which serves as a supply path for hydraulic fluid when the piston 27 moves forward; port B 50, which serves as a discharge path for hydraulic fluid when the piston 27 moves forward; and port C 70, which serves as a discharge path for hydraulic fluid when port B 50 is blocked by the piston 27 when the piston 27 moves forward.

[0077] Here, when the piston 27 is retracting, hydraulic fluid is supplied to port B 50, and when the hydraulic fluid is discharged from port A 40, hydraulic fluid is also supplied to port C 70, and port B 50 and port C 70 are connected to each other so that the hydraulic fluid supplied to port C 70 enables the piston 27 to retract. In this way, the injection molding machine 100 in the embodiment is configured.

[0078] <Characteristics of the manifested form> Next, I will explain the characteristic features of the embodiment.

[0079] A key feature of the implemented configuration is that, as shown in Figures 7 and 8, for example, the B port 50 and the C port 70 are connected to each other. This allows for the retraction of the piston 27, such as "metering operation" and "suck-back operation," to be achieved simply by providing hydraulic equipment to supply hydraulic fluid to the B port 50, without providing hydraulic equipment to supply hydraulic fluid to the C port 70, as shown in Figure 10. This is because, in the implemented configuration, as a result of the B port 50 and the C port 70 being connected to each other, the hydraulic fluid supplied to the B port 50 is inevitably also supplied to the C port 70, and the hydraulic fluid supplied to the C port 70 applies pressure to the side of the piston 27, thereby allowing the piston 27 to move in the retraction direction.

[0080] In other words, according to the features of the embodiment, it becomes unnecessary to provide a dedicated flow channel piping and dedicated hydraulic equipment to supply hydraulic fluid to the C port 70 in order to realize the retraction movement of the piston 27, and as a result, the configuration of the hydraulic system 28A can be simplified. Specifically, it becomes possible to eliminate the flow channel piping that supplies hydraulic fluid to the C port 70, the solenoid valve 38 and the flow control valve 39, thereby simplifying the configuration of the hydraulic system 28A.

[0081] Therefore, depending on the embodiment, the manufacturing cost of the injection molding machine 100 can be reduced and the reliability of the injection molding machine 100 can be improved by simplifying the configuration of the hydraulic system 28A. This is because if dedicated flow path piping and hydraulic equipment can be removed from the C port 70, the number of parts in the hydraulic system 28A can be reduced, thereby reducing the manufacturing cost of the hydraulic system 28A. Furthermore, if the configuration of the hydraulic system 28A is simplified, malfunctions (failures) of the hydraulic system 28A will be less likely to occur, leading to improved reliability of the injection molding machine 100.

[0082] From the above, the technical concept in the implemented form is an excellent technical concept because it simplifies the configuration of the hydraulic system 28A simply by changing the configuration of the B port 50 and C port 60, which were physically separated from each other, to a configuration in which they are physically connected to each other, thereby achieving remarkable effects such as reducing the manufacturing cost of the injection molding machine 100 and improving the reliability of the injection molding machine 100.

[0083] Although the present invention has been specifically described above based on its embodiments, it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from its essence. [Explanation of symbols]

[0084] 1 Mold clamping device 2 Injection device 10 Fixed plate 11 Movable plate 12 Fixed type 13 Movable type 21 Hoppa 22 volts 23 Screw 24 Screw rotation motor 25 Heater 26 nozzles 27 Pistons 28 Hydraulic System 28A Hydraulic System 28R Hydraulic System 30 pumps 31 Accumulator 32 Servo valves 33 tanks 33a Solenoid valve 34 Solenoid valve 35 Logic Valve 36 Accumulator 37 tanks 38 Solenoid valve 39 Flow control valve 40 A ports 50 B ports 60 C ports 70 C ports 100 injection molding machine CAV Confined space

Claims

1. An injection device that performs the injection operation of material, A clamping device for molding the material injected from the injection device, An injection molding machine equipped with, The injection device is, Screw and, The piston connected to the screw, A hydraulic unit that drives the piston in the axial direction, It has, The aforementioned hydraulic section is The first port, which serves as a supply path for hydraulic fluid during the forward movement of the piston, A second port which serves as a discharge path for the hydraulic fluid during the forward movement of the piston, When the piston moves forward, the second port is blocked by the piston, and the third port becomes the discharge path for the hydraulic fluid. It has, The first port is provided at the first axial position, The second port is provided at the second axial position, The third port is provided at the third position in the axial direction, The second position is located further forward of the piston than the first position. The third position is located further forward of the piston than the first position. An injection molding machine in which the second port and the third port are integrated such that, when the piston is retracting, the hydraulic fluid is supplied to the second port, and when the hydraulic fluid is discharged from the first port, the hydraulic fluid is also supplied to the third port, and the hydraulic fluid supplied to the third port enables the piston to retract.

2. In the injection molding machine according to claim 1, An injection molding machine in which the cross-sectional area of ​​the third port is smaller than the cross-sectional area of ​​the second port.

3. In the injection molding machine according to claim 1, An injection molding machine in which the forward movement of the piston is defined as the injection operation of the material.

4. In the injection molding machine according to claim 1, In an injection molding machine, the retraction of the piston refers to the suck-back operation.

5. In the injection molding machine according to claim 1, In an injection molding machine, the retraction of the piston refers to the metering operation.

6. In the injection molding machine according to claim 1, The aforementioned material is a metal material, and the injection molding machine.

7. In the injection molding machine according to claim 6, The aforementioned material is a magnesium alloy, and the injection molding machine.

8. An injection device that performs the injection operation of a material, The injection device is, Screw and, The piston connected to the screw, A hydraulic unit that drives the piston in the axial direction, It has, The aforementioned hydraulic section is The first port, which serves as a supply path for hydraulic fluid during the forward movement of the piston, A second port which serves as a discharge path for the hydraulic fluid during the forward movement of the piston, When the piston moves forward, the second port is blocked by the piston, and the third port becomes the discharge path for the hydraulic fluid. It has, The first port is provided at the first axial position, The second port is provided at the second axial position, The third port is provided at the third position in the axial direction, The second position is located further forward of the piston than the first position. The third position is located further forward of the piston than the first position. An injection device in which the second port and the third port are integrated such that, when the piston is retracting, the hydraulic fluid is supplied to the second port, and when the hydraulic fluid is discharged from the first port, the hydraulic fluid is also supplied to the third port, and the hydraulic fluid supplied to the third port enables the piston to retract.

9. In the injection apparatus according to claim 8, An injection device in which the cross-sectional area of ​​the third port is smaller than the cross-sectional area of ​​the second port.

10. In the injection apparatus according to claim 8, An injection device in which the forward movement of the piston refers to the injection operation of the material.

11. In the injection apparatus according to claim 8, In an injection device, the retraction of the piston refers to the suck-back operation.

12. In the injection apparatus according to claim 8, The retraction of the piston refers to the metering operation in the injection device.

13. In the injection apparatus according to claim 8, The aforementioned material is a metallic material, and the device is an injection molding machine.

14. In the injection apparatus according to claim 13, The aforementioned material is a magnesium alloy, and the device is an injection molding machine.

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