Injection device and molding machine

Abstract

To provide an injection device allowed to reduce the pressure given to a run-around circuit.SOLUTION: In an injection device 9, the inside of an injection cylinder member 29 is partitioned into a rod-side chamber 29r on a side where a rod 33 is located by an injection piston 31 and a head-side chamber 29h on an opposite side thereto. An injection accumulator 53A supplies operation fluid to the head-side chamber 29h. A first check valve 55 permits a flow from the injection accumulator 53A side toward the head-side chamber 29h side and prohibits a flow in an opposite direction thereto. A run-around circuit 57 has a flow passage 59 allowing the operation fluid to flow from the rod-side chamber 29r toward the head-side chamber 29h when the injection piston 31 moves toward the rod-side chamber 29r side. The flow passage 59 has a first end 59a connected to the rod-side chamber 29r, and a second end 59b connected between the injection accumulator 53A and the first check valve 55.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an injection device that injects a molding material into a mold, and a molding machine including the injection device. The molding machine is, for example, a die-casting machine that molds a metal as a molding material, or an injection molding machine that molds a resin as a molding material. [Background technology]

[0002] Known drive units that drive a plunger that pushes molding material into a mold include hydraulic cylinders (injection cylinders) (see, for example, Patent Documents 1 to 7 listed below). The injection cylinder includes, for example, an injection cylinder member, an injection piston housed in the injection cylinder member, and a rod fixed to the injection piston. The rod extends outward from the injection cylinder member and is connected to the plunger. The interior of the injection cylinder member is divided by the injection piston into a rod-side chamber on the side where the rod is located and a head-side chamber on the opposite side. For example, when hydraulic fluid is supplied from an accumulator to the head-side chamber, the injection piston moves toward the rod side, thereby driving the plunger.

[0003] A run-around circuit is known that supplies hydraulic fluid discharged from the rod-side chamber to the head-side chamber when the injection piston moves toward the rod side as described above (for example, Patent Documents 1 to 7 listed below). By providing a run-around circuit, the required amount of hydraulic fluid is reduced compared to, for example, a configuration in which hydraulic fluid in the rod-side chamber is discharged to a tank.

[0004] Also known is a drive unit having a check valve (also called a non-return valve) that allows flow from the accumulator side to the head-side chamber side and prohibits flow in the opposite direction (for example, Patent Documents 3, 6, and 7 listed below). This prevents backflow from the head-side chamber side to the accumulator side, even if high pressure occurs in the head-side chamber, for example.

[0005] In Patent Documents 3, 6, and 7, both a run-around circuit and the above-mentioned check valve are provided. One end of the flow path of the run-around circuit is connected to the rod-side chamber, and the other end is connected between the check valve and the head-side chamber. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-172899 [Patent Document 2] Japanese Patent Application Publication No. 10-249510 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-16718 [Patent Document 4] Japanese Patent Publication No. 2020-142245 [Patent Document 5] Japanese Patent Application Laid-Open No. 2010-167608 [Patent Document 6] Japanese Patent Application Laid-Open No. 2012-11395 [Patent Document 7] Japanese Patent Application Laid-Open No. 2012-51026 Summary of the Invention [Problem to be solved by the invention]

[0007] There is a need for an injection device and a molding machine that can reduce the pressure applied to the run-around circuit. [Means for solving the problem]

[0008] an injection device according to one aspect of the present disclosure, comprising: a rod connected to a plunger that pushes a molding material into a mold; an injection piston fixed to the rod; and an injection cylinder member that houses the injection piston, the interior of the injection cylinder member being divided by the injection piston into a rod-side chamber on the side where the rod is located and a head-side chamber on the opposite side; a supply source that supplies hydraulic fluid to the head-side chamber; a first check valve that allows flow from the supply source side to the head-side chamber side and prohibits flow in the opposite direction; and a runaround circuit that includes a flow path that allows hydraulic fluid to flow from the rod-side chamber to the head-side chamber when the injection piston moves toward the rod-side chamber side, the flow path having a first end connected to the rod-side chamber and a second end connected between the supply source and the first check valve.

[0009] A molding machine according to one aspect of the present disclosure includes the injection device and a mold clamping device that clamps the mold. [Effects of the Invention]

[0010] According to the above configuration, the pressure applied to the run-around circuit can be reduced. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a side view showing the configuration of a main part of a die casting machine according to an embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing the configuration of a main part of an injection device of the die-casting machine of FIG. 1. [Figure 3] 3 is a cross-sectional view showing an example of the configuration of a check valve included in the run-around circuit of the injection device of FIG. 2. [Figure 4] FIG. 10 is a schematic diagram showing another example of a pressure increasing mechanism included in the injection device. [Figure 5] 5(a) and 5(b) are schematic diagrams showing still another example of a pressure increasing mechanism provided in the injection device. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Outline of the embodiment) 1 is a side view (partially including a cross-sectional view) that schematically shows the configuration of a die-casting machine 1 according to an embodiment. The up-down direction along the plane of the drawing is the vertical direction.

[0013] The die-casting machine 1 produces a die-cast product (a molded product in a broader sense) by filling a mold 101 (space 107) with molten metal (liquid metal material, not shown). The filling of the molten metal into the space 107 is carried out by pushing out the molten metal in a sleeve 21 that communicates with the space 107 with a plunger 23. The plunger 23 is driven by an injection cylinder 27 of the injection device 9.

[0014] 2 is a schematic cross-sectional view showing the configuration of the main part of the injection device 9. The left and right directions in FIG. 1 and FIG. 2 are the same.

[0015] The injection cylinder 27 has a rod 33 connected to the plunger 23 (see also FIG. 1). The rod 33 is fixed to an injection piston 31 housed in the injection cylinder member 29. The injection piston 31 divides the interior of the injection cylinder member 29 into a rod-side chamber 29r on the side where the rod 33 is located and a head-side chamber 29h on the opposite side.

[0016] When hydraulic fluid (e.g., oil) is supplied from the injection accumulator 53A to the head-side chamber 29h, the injection piston 31 moves forward toward the rod-side chamber 29r. This causes the plunger 23 fixed to the injection piston 31 via the rod 33 to also move forward, and as a result, the molten metal in the sleeve 21 is injected into the space 107 of the mold 101.

[0017] A first check valve 55 is interposed between the injection accumulator 53A and the head-side chamber 29h. The first check valve 55 allows flow from the injection accumulator 53A side to the head-side chamber 29h side and prohibits flow in the opposite direction. This reduces backflow, for example, from the head-side chamber 29h side to the injection accumulator 53A side.

[0018] The injection device 9 has a run-around circuit 57 (return flow path 59) that causes the hydraulic fluid to flow from the rod-side chamber 29r to the head-side chamber 29h when the injection piston 31 moves forward. By providing the run-around circuit 57, the required amount of hydraulic fluid is reduced compared to, for example, a mode in which the hydraulic fluid in the rod-side chamber 29r is discharged to the tank 61 when the injection piston 31 moves forward.

[0019] The runaround circuit 57 has a first end 59a connected to the rod-side chamber 29r and a second end 59b communicating with the head-side chamber 29h. However, the second end 59b is not directly connected to the head-side chamber 29h (or, from another perspective, without a valve), but communicates with the head-side chamber 29h via the first check valve 55. In other words, the second end 59b is connected between the injection accumulator 53A and the first check valve 55.

[0020] Therefore, for example, when the pressure in the head side chamber 29h becomes higher than the pressure in the injection accumulator 53A, the likelihood of that high pressure being applied to the run-around circuit 57 is reduced. As a result, for example, the pressure resistance of the run-around circuit 57 can be lowered, thereby reducing costs. From another perspective, the need to provide a check valve separate from the first check valve 55 near the second end 59b of the return flow path 59 in order to reduce the pressure applied to the run-around circuit 57 is reduced, thereby reducing costs. Furthermore, for example, by reducing the likelihood of high pressure being applied to the run-around circuit 57, leakage of hydraulic fluid in the run-around circuit 57 can be reduced, improving the accuracy of operation of the injection unit 9 and ultimately improving the quality of molded products.

[0021] The above is an overview of the injection device 9 and the die-casting machine 1 according to the embodiment. The embodiment will be described below in the following order. 1. Die-casting machine (Figure 1) 2. Injection unit (Figure 2) 2.1.Injection cylinder 2.2.Hydraulic device 2.2.1. Tanks and pumps 2.2.2. Section from injection accumulator to head side chamber 2.2.3. Section from the booster accumulator to the rear chamber 2.2.4. Section from the rod side chamber to the tank 2.2.5. Runaround Circuit 2.3. Example of valve configuration for run-around circuit (Figure 3) 2.4. Example of injection unit operation 2.4.1.Low speed injection 2.4.2.High speed injection 2.4.3. Pressure boost and pressure maintenance 3. Injection unit variations (Fig. 4 to Fig. 5(b)) 4. Summary of embodiments

[0022] (1. Die-casting machine) As described above, the die-casting machine 1 (FIG. 1) injects molten metal into a die 101. However, the die-casting machine 1 may also inject a metal material in a solid-liquid coexistence state. The solid-liquid coexistence state is a semi-solidified state in which solidification has progressed from a liquid state, or a semi-molten state in which melting has progressed from a solid state. In a broader sense, the molten metal and the metal material in a solid-liquid coexistence state are unhardened metal materials (molding materials). The metal is, for example, aluminum or an aluminum alloy.

[0023] The mold 101 includes, for example, a fixed mold 103 and a movable mold 105. A main portion of a space 107 in the mold 101 into which the molten metal is filled is formed between the fixed mold 103 and the movable mold 105. The fixed mold 103 is a mold that does not move. The movable mold 105 is a mold that moves in a direction opposite to the fixed mold 103 (mold opening / closing direction). The mold opening / closing direction is, for example, a horizontal direction.

[0024] The die-casting machine 1 has, for example, a machine main body 3 that performs mechanical operations for molding, a controller 5 that controls the operation of the machine main body 3, and an interface 13 that mediates between the controller 5 and an operator.

[0025] The machine main body 3 has, for example, in addition to the injection device 9 already described, a mold clamping device 7 that opens, closes, and clamps the mold 101, and an extrusion device 11 that extrudes the die-cast product from the fixed mold 103 or the movable mold 105 (the movable mold 105 in FIG. 1). In the machine main body 3, the components other than the injection device 9 (for example, the components of the mold clamping device 7 and the extrusion device 11) and their operations may be various, and may be, for example, publicly known components and operations. Note that explanations of components and operations that may be publicly known will be omitted as appropriate.

[0026] In a molding cycle, the mold clamping unit 7 moves the movable mold 105 toward the fixed mold 103 to close the mold. Furthermore, the mold clamping unit 7 applies a clamping force to the mold 101 according to the extension amount of the tie bars (reference numerals omitted) to clamp the mold. A space 107 is formed inside the clamped mold 101. The injection unit 9 injects and fills the space 107 with molten metal. The molten metal in the space 107 is cooled and solidified by the heat absorbed by the mold 101. In other words, the molten metal becomes a molded product. Thereafter, the mold clamping unit 7 moves the movable mold 105 in a direction away from the fixed mold 103 to open the mold. At this time, or thereafter, the extrusion unit 11 extrudes the molded product from the movable mold 105.

[0027] The controller 5 may be configured to include, for example, a computer (not shown). The computer may be configured to include, for example, a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and an auxiliary storage device (e.g., a hard disk drive (HDD) or a solid state drive (SSD)), (not shown). The CPU executes programs stored in the ROM and / or the auxiliary storage device, thereby configuring various functional units that perform various calculations (including control). The controller 5 may also include a logic circuit that performs certain operations, a power supply circuit, or a driver.

[0028] The controller 5 may be provided, for example, in a control panel (not shown). Furthermore, a part of the controller 5 may be configured as a part of the interface 13. The controller 5 may be integrated in one location in terms of hardware, or may be distributed to multiple locations. The controller 5 may be configured to include a lower-level controller for each of the mold clamping unit 7, the injection unit 9, and the extrusion unit 11, and a higher-level controller that performs control such as synchronization between these lower-level controllers, or may not be configured in this way.

[0029] When focusing on each device included in the die casting machine 1, the controller 5 may be regarded as a controller for that device. For example, the controller 5 may be regarded as a controller for the injection device 9. The same applies to the interface 13; for example, the interface 13 may be regarded as a component of the injection device 9.

[0030] The interface 13 may be provided at an appropriate position, and in the illustrated example, it is provided on a fixed die plate (reference numeral omitted) of the mold clamping unit 7. The interface 13 has an input device 15 that accepts input operations from an operator, and a display device 17 that displays images. The display device 17 is configured, for example, by a liquid crystal display or an organic EL display, and also configures a display unit of a touch panel. The input device 15 is configured, for example, by a mechanical switch and the above-mentioned touch panel.

[0031] (2. Injection device) 1 and 2 includes the above-described sleeve 21, plunger 23, and injection cylinder 27, as well as a hydraulic device 51 shown in Fig. 2. The hydraulic device 51 controls the hydraulic pressure applied to the injection cylinder 27, and includes the above-described injection accumulator 53A, first check valve 55, run-around circuit 57, etc.

[0032] In the description of the injection unit 9, the mold 101 side may be referred to as the front side and the opposite side as the rear side. Also, since the sleeve 21 and plunger 23 can be considered as consumables, unlike the description here, only the drive unit that drives the plunger 23 (injection cylinder 27 and hydraulic device 51 in this embodiment) may be considered as the injection unit.

[0033] 1, the sleeve 21 is, for example, a cylindrical member, and has a supply port 21a on the top surface for receiving molten metal into the sleeve 21. The plunger 23 has, for example, a plunger tip 23a that can slide back and forth within the sleeve 21, and a plunger rod 23b whose tip is fixed to the plunger tip 23a.

[0034] When clamping of the mold 101 by the mold clamping device 7 is completed, a water supply device (not shown) pours one shot of molten metal from the supply port 21a into the sleeve 21. Then, the plunger 23 slides forward within the sleeve 21 from the position shown in FIG. 1, whereby the molten metal within the sleeve 21 is pushed out (injected) into the mold 101.

[0035] The injection device 9 has various sensors (not shown). The controller 5 controls the drive unit of the injection device 9 based on the detection values of the various sensors. The various sensors may be provided in the same manner as in known injection devices. For example, although not particularly shown, the injection device 9 may have a position sensor for detecting the position and speed of the plunger 23 and a pressure sensor for detecting the pressure applied by the plunger 23 to the molten metal. Furthermore, the control of the drive unit of the injection device 9 by the controller 5 may also be basically the same as known control.

[0036] The injection cylinder 27 and the hydraulic device 51 will be described below in order.

[0037] (2.1. Injection Cylinder) The injection cylinder 27 may have various configurations, for example, a known configuration. The injection cylinder 27 illustrated in Fig. 2 is a so-called booster type. For convenience, in the description of the embodiment, the injection cylinder 27 is mainly a booster type, and expressions that assume that the injection cylinder 27 is a booster type may be used unless otherwise specified.

[0038] The injection cylinder 27 has a booster cylinder member 35 and a booster piston 37 in addition to the injection cylinder member 29, injection piston 31, and rod 33 described above. The booster cylinder member 35 and the booster piston 37 apply a pressure to the head side chamber 29h that is higher than the pressure of the working fluid supplied to the booster cylinder member 35. This makes it possible to increase the pressure applied by the plunger 23 to the molten metal in the mold 101, for example. Note that the combination of the injection cylinder member 29 and the booster cylinder member 35 illustrated in FIG. 2 may be regarded as a single cylinder member.

[0039] The injection cylinder member 29, injection piston 31, and rod 33 have been outlined above. These are arranged, for example, coaxially with respect to the plunger 23. The rear end of the plunger 23 and the front end of the rod 33 are connected, for example, by a coupling 25 (FIG. 1). The injection cylinder member 29 is fixed to the factory floor or the like directly or indirectly via an immovable part of the mold clamping unit 7, and is therefore immovable. Therefore, as described above, when the injection piston 31 moves relative to the injection cylinder member 29, the plunger 23 is driven.

[0040] The cylinder member (29 and / or 35) is, for example, a roughly cylindrical member. The shape of the internal cross section (cross section perpendicular to the axial direction) of the cylinder member is, for example, circular. For convenience, in the description of the embodiments, it is assumed that the internal cross section of the cylinder member and the cross section of the piston are circular. Therefore, for example, the relationship between the diameter and the cross section (area) is the same. The external shape (shape of the outer surface) of the cylinder member is arbitrary.

[0041] A packing (not shown) may be interposed between the injection piston 31 and the injection cylinder member 29. Even when a packing is interposed, the injection piston 31 is said to slide inside the injection cylinder member 29. However, the packing fixed to the injection piston 31 may be regarded as part of the injection piston 31. The above explanation regarding the packing may also be applied to other similar members (for example, the booster piston 37 and the booster cylinder member 35) as appropriate.

[0042] The booster cylinder member 35 has a small-diameter cylinder portion 35x that communicates with the head-side chamber 29h and a large-diameter cylinder portion 35y that is fixed to the small-diameter cylinder portion 35x. The inner diameter of the large-diameter cylinder portion 35y is larger than the inner diameter of the small-diameter cylinder portion 35x.

[0043] The booster piston 37 has a small-diameter piston portion 37x that slides in the small-diameter cylinder portion 35x and a large-diameter piston portion 37y that slides in the large-diameter cylinder portion 35y. The small-diameter piston portion 37x and the large-diameter piston portion 37y are fixed together. The interior of the large-diameter cylinder portion 35y is divided by the large-diameter piston portion 37y into a front chamber 35a on the small-diameter cylinder portion 35x side and a rear chamber 35b on the opposite side.

[0044] The area (pressure-receiving area) of the booster piston 37 that receives forward pressure from the hydraulic fluid in the rear-side chamber 35b is larger than the area (pressure-receiving area) that receives rearward pressure from the hydraulic fluid in the small-diameter cylinder portion 35x. Therefore, for example, by depressurizing the front-side chamber 35a (for example, by connecting the front-side chamber 35a to the tank 61), a pressure higher than the pressure applied to the rear-side chamber 35b can be applied to the small-diameter cylinder portion 35x (and the head-side chamber 29h).

[0045] The small-diameter piston portion 37x and the large-diameter piston portion 37y may be fixed to each other by, for example, integrally forming them from the same material, or by fabricating them separately and connecting them with screws or the like. Furthermore, when it is said that the small-diameter piston portion 37x and the large-diameter piston portion 37y are fixed to each other, a piston portion (i.e., another portion) having a smaller diameter than the small-diameter piston portion 37x may be interposed between them. While the fixation between the small-diameter piston portion 37x and the large-diameter piston portion 37y is used as an example here, the term "fixed" may be broadly interpreted to apply to other portions or members as well, unless a contradiction arises.

[0046] In the example of FIG. 2, the booster cylinder member 35 is fixed in line to the rear end of the injection cylinder member 29, and the inner diameter of the small-diameter cylinder portion 35x is the same as the inner diameter of the injection cylinder member 29. Unlike the example shown, the inner diameter of the small-diameter cylinder portion 35x may be different from the inner diameter of the injection cylinder member 29. For example, the former may be smaller than the latter. Furthermore, although not specifically shown, as can be understood from the fact that separate-type booster cylinders are well known, the booster cylinder member 35 does not have to be fixed in line to the rear end of the injection cylinder member 29.

[0047] Although not specifically shown, the booster piston 37 may have a rod (reference numeral omitted) protruding forward from the small diameter piston portion 37x. For example, when the injection piston 31 is retracted by supplying hydraulic fluid to the rod side chamber 29r, such a rod retracts the booster piston 37 together with the injection piston 31, and / or contributes to indirectly determining the retraction limit of the injection piston 31 by the retraction limit of the booster piston 37.

[0048] (2.2. Hydraulic device) The hydraulic device 51 may have various configurations, for example, a known configuration, except that the runaround circuit 57 is connected between the injection accumulator 53A and the first check valve 55. In the example of FIG. 2, the configuration is as follows.

[0049] The hydraulic device 51 includes the injection accumulator 53A, first check valve 55, and tank 61 described above, as well as the following components: A booster accumulator 53B that supplies hydraulic fluid to the rear chamber 35b; A booster valve 56 that controls the flow between the booster accumulator 53B and the rear chamber 35b; A flow control valve 63 that constitutes a so-called meter-out circuit; and A pump 65 that delivers hydraulic fluid to the injection accumulator 53A, etc. FIG. 2 shows only the essential parts of the hydraulic device 51 that move the plunger 23 forward. The hydraulic device 51 may include various other components besides those described above.

[0050] For example, when hydraulic fluid flows from the booster accumulator 53B to the rear chamber 35b, if the volume of the flow path therebetween is large and the movement of the booster piston 37 is small, the hydraulic fluid in the booster accumulator 53B does not reach the rear chamber 35b. Even in such a case, for convenience, it may be expressed as hydraulic fluid being supplied (or flowing) from the booster accumulator 53B to the rear chamber 35b. The same applies to other components and the discharge of hydraulic fluid. Furthermore, the terms "supply of hydraulic fluid" and "application of hydraulic pressure" may be interchangeable as long as no contradiction occurs.

[0051] (2.2.1. Tanks and Pumps) The tank 61 stores hydraulic fluid. Unlike the description here, the tank 61 may be a facility separate from the die-casting machine 1 (injection device 9). For convenience of illustration, the tank 61 is shown in multiple locations. In an actual configuration, there may be multiple tanks 61, or there may be only one tank 61. The tank 61 is, for example, an open-to-air type, and basically holds hydraulic fluid under atmospheric pressure. As can be understood from known injection devices, hydraulic fluid may flow into the tank 61 from various components. In FIG. 2, the rod-side chamber 29r and the front-side chamber 35a are illustrated as typical examples.

[0052] The pump 65 is driven by an electric motor (not shown) to deliver the hydraulic fluid. Unlike the embodiment described above, the pump 65 may be a separate facility from the die-casting machine 1 (injection device 9). The configuration of the pump 65 is arbitrary. For example, the pump 65 may be a rotary pump, a plunger pump, a fixed displacement pump, a variable displacement pump, a one-way pump, or a two-way pump. The pump 65 may be driven only when necessary, or may be driven constantly.

[0053] As is understood from known injection devices, the pump 65 may supply hydraulic fluid to various components of the die casting machine 1 (injection device 9). In the example of Fig. 2, a pump line 67 is illustrated as a flow path for supplying hydraulic fluid from the pump 65 to the injection accumulator 53A to accumulate pressure in the injection accumulator 53A.

[0054] One end of the pump line 67 is connected to the discharge port of the pump 65. The other end of the pump line 67 is connected between the injection accumulator 53A and the first check valve 55. Although not particularly shown, the pump line 67 (or between the pump line 67 and the injection accumulator 53A) may be provided with a valve that allows or prohibits the flow of hydraulic fluid between the pump line 67 and the injection accumulator 53A (it is also possible not to provide such a valve).

[0055] It should be noted that the injection accumulator 53A may accumulate pressure without using the pump 65. In other words, the pump line 67 is not an essential requirement. For example, the rod 33 may be moved backward by an electric motor to return the hydraulic fluid in the head-side chamber 29h to the injection accumulator 53A, or the hydraulic fluid may be supplied to the injection accumulator 53A by a hydraulic pressure source (for example, a hydraulic cylinder driven by an electric motor) separate from the pump 65.

[0056] (2.2.2. Section from injection accumulator to head side chamber) The injection accumulator 53A may be of various types, such as a weight type, a spring type, a gas pressure type, a piston type, or a bladder type. In a weight type, pressure is applied to the hydraulic fluid by the gravity of a weight. In a spring type, pressure is applied to the hydraulic fluid by the restoring force of a spring. In a gas pressure type, compressed gas applies pressure to the hydraulic fluid by directly contacting the hydraulic fluid. In a piston type, compressed gas applies pressure to the hydraulic fluid via a piston. In a bladder type, compressed gas applies pressure to the hydraulic fluid via a flexible bladder (diaphragm). In the gas pressure, piston, and bladder types, the gas is, for example, air or an inert gas (e.g., nitrogen).

[0057] The pressure of injection accumulator 53A may be set to the same level as that of a general die-casting machine. The specific magnitude varies depending on the performance required of the die-casting machine. For example, the pressure is 13 MPa or more and 15 MPa or less immediately before the start of injection (or, from another perspective, when pressure accumulation in injection accumulator 53A is completed during the molding cycle).

[0058] As described above, the first check valve 55 allows flow from the injection accumulator 53A side to the head-side chamber 29h side and prohibits flow in the opposite direction. From another perspective, the first check valve 55 closes (self-closes) by itself when the pressure on the head-side chamber 29h side increases relative to the pressure on the injection accumulator 53A side. The specific configuration of the first check valve 55 may be any of various known configurations. Furthermore, the first check valve 55 may be configured to be able to open and / or close by introducing pilot pressure, or may not be configured in this way.

[0059] 2, the first check valve 55 is configured to be able to be closed by the introduction of pilot pressure. Therefore, the first check valve 55 can prohibit flow from the injection accumulator 53A to the head-side chamber 29h by the introduction of pilot pressure, and can allow the flow by stopping the introduction of pilot pressure. In other words, the first check valve 55 is configured to be able to control the supply of working fluid from the injection accumulator 53A to the head-side chamber 29h.

[0060] In the example of FIG. 2, the supply flow path 54 from the injection accumulator 53A to the head side chamber 29h does not have any valves other than the first check valve 55. Therefore, it can be said that no flow control valve is present in the section of the supply flow path 54 between the second end 59b of the run-around circuit 57 and the injection accumulator 53A. It can also be said that no valves controlled by the controller 5 during the molding cycle (e.g., solenoid or pilot valves) are present in the section. It can also be said that no valves that can operate during the molding cycle (e.g., the above-mentioned controlled valves and non-pilot check valves) are present in the section. Note that, unless otherwise specified, the valves described in the description of the embodiments do not include manual valves provided for maintenance and management, etc.

[0061] However, unlike the illustrated example, a valve may be provided in the supply flow path 54. For example, a flow control valve constituting a so-called meter-in circuit may be provided between the injection accumulator 53A and the first check valve 55. In such a case, the first check valve 55 does not have to be configured to be closed by the introduction of pilot pressure. The description of the flow control valve 63 (described later) may be applied to the flow control valve of the meter-in circuit, unless a contradiction arises.

[0062] (2.2.3. Section from booster accumulator to rear chamber) The above description of the type and pressure setting of the injection accumulator 53A may be applied to the booster accumulator 53B. The configuration (type, dimensions, etc.) and / or pressure setting of the booster accumulator 53B in one injection device 9 may be different from or the same as the configuration and / or pressure setting of the injection accumulator 53A.

[0063] However, the pressure at the completion of pressure accumulation in the pressure-boosting accumulator 53B (or, from another perspective, immediately before the start of pressure increase) is set so that the pressure that the pressure-boosting piston 37 applies to the head side chamber 29h is higher than the pressure at the completion of discharge from the injection accumulator 53A (or, from another perspective, immediately before the start of pressure increase). This enables pressure increase. Note that the pressure at the completion of pressure accumulation in the pressure-boosting accumulator 53B and / or the pressure that the pressure-boosting piston 37 applies to the head side chamber 29h due to the pressure at the completion of pressure accumulation may be higher than the pressure at the completion of pressure accumulation in the injection accumulator 53A (or, from another perspective, immediately before the start of injection).

[0064] The pressure-boosting valve 56 may have any configuration as long as it can allow or prohibit the supply of hydraulic fluid from the pressure-boosting accumulator 53B to the rear chamber 35b. For example, the pressure-boosting valve 56 may be configured as a pilot-operated check valve, similar to the first check valve 55. Furthermore, a flow control valve that forms a so-called meter-in circuit may be provided as the pressure-boosting valve 56 or in addition to the pressure-boosting valve 56.

[0065] (2.2.4. Section from the rod side chamber to the tank) A part of the discharge flow path 69 from the rod side chamber 29r to the tank 61 on the rod side chamber 29r side is common to (shared with) a part of the return flow path 59 of the run-around circuit 57. However, the discharge flow path 69 and the return flow path 59 may be separate flow paths over their entirety.

[0066] As described above, the discharge flow path 69 is provided with the flow control valve 63 that constitutes a so-called meter-out circuit. The flow rate of the hydraulic fluid discharged from the rod side chamber 29r is controlled by the flow control valve 63. This controls, for example, the forward movement speed of the injection piston 31.

[0067] In the embodiment in which the discharge flow path 69 and the return flow path 59 share a portion of the same, as described above, the flow control valve 63 is located, for example, closer to the tank 61 than the shared portion. However, unlike the illustrated example, the flow control valve 63 may be located in the shared portion.

[0068] The flow control valve 63 may have any configuration. For example, the flow control valve 63 may be configured as a pressure-compensated flow adjustment valve that can maintain a constant flow rate even if there are pressure fluctuations. Alternatively, the flow control valve 63 may be configured as a servo valve that is used in a servo mechanism and can modulate the flow rate steplessly (continuously to any value) in response to an input signal. The flow control valve 63 may be driven by a solenoid, or may be driven by pilot pressure, or may have a main valve driven by pilot pressure and a pilot valve driven by a solenoid that controls the pilot pressure to the main valve.

[0069] (2.2.5. Run-around circuit) The runaround circuit 57 has, for example, in addition to the previously described reflux flow path 59, a second check valve 71 that controls the flow of hydraulic fluid in the reflux flow path 59. The second check valve 71 contributes to controlling the on / off of the runaround circuit 57, for example, by allowing or prohibiting a flow from the rod side chamber 29r to the head side chamber 29h. The reflux flow path 59 and the second check valve 71 will be described below in order.

[0070] The connection positions of the first end 59a and the second end 59b of the reflux flow path 59 have been described above. It has also been described above that a portion of the first end 59a side may be shared with a portion of the discharge flow path 69. In the example of FIG. 2, the reflux flow path 59 is not shared with the pump line 67. From another perspective, the reflux flow path 59 and the pump line 67 are connected separately to the supply flow path 54 (the flow path from the injection accumulator 53A to the first check valve 55). Either of the connection positions of the two to the supply flow path 54 may be on the injection accumulator 53A side. However, unlike the illustrated example, the reflux flow path 59 and the pump line 67 may share a portion (for example, the portion connected to the supply flow path 54) with each other.

[0071] The reflux flow path 59 (and other flow paths) may be configured appropriately. For example, the reflux flow path 59 may be configured by a pipe that can be considered a rigid body, a flexible hose, and / or a block. As an example, all or a part of the reflux flow path 59 on the second end 59b side of the second check valve 71, or the entire reflux flow path 59, may be configured by a pipe and / or a hose.

[0072] The pipe is made of, for example, metal (e.g., steel) and / or resin. The hose is not limited to those made of flexible materials, but also includes those whose flexibility is achieved by bellows. An example of a flexible material is resin (including rubber). The block is made of, for example, metal and / or resin.

[0073] The second check valve 71, for example, allows flow from the rod-side chamber 29r (first end 59a) side to the head-side chamber 29h (second end 59b) side and prohibits flow in the opposite direction. In the example of Fig. 2, the second check valve 71 is assumed to have the configuration shown in Fig. 3 (described later), and is closed in conjunction with the operation of the flow control valve 63 to prohibit flow from the rod-side chamber 29r side to the head-side chamber 29h side (turning off the runaround circuit 57).

[0074] Unlike the above configuration, the second check valve 71 may be closed by the introduction of pilot pressure. The runaround circuit 57 may also have another valve in addition to the second check valve 71. Instead of the second check valve 71, another valve (for example, a switching valve or a pilot-operated check valve that is oriented in the opposite direction to the second check valve 71) may be provided to control the on / off state of the runaround circuit 57.

[0075] (2.3. Example of run-around circuit valve configuration) Fig. 3 is a cross-sectional view that schematically shows an example of the configuration of the second check valve 71 and the flow control valve 63. Fig. 3 shows a state in which the flow control valve 63 and the second check valve 71 are closed.

[0076] 3, the illustration of details is omitted. For example, the configuration for driving the flow control valve 63 (for example, a port for introducing pilot pressure) is not shown. Also, the injection cylinder 27 is depicted as a so-called single-barrel injection cylinder, with the booster cylinder member 35 and booster piston 37 omitted.

[0077] In this configuration example, the second check valve 71 is connected to the flow control valve 63. As a result, the second check valve 71 is closed in conjunction with the operation of the flow control valve 63. More specifically, this is as follows.

[0078] The structure of the second check valve 71 may basically be similar to various structures, including known structures, except for the structure related to connection with the flow control valve 63. For example, the second check valve 71 has a hollow main body 71a, a valve element 71b that is movable left and right in FIG. 3 within the main body 71a, and a spring 71c that biases the valve element 71b to the left in FIG. 3. The main body 71a has a port 71d that communicates with the rod-side chamber 29r and a port 71e that communicates with the head-side chamber 29h. The specific shapes of the components and the positional relationship of the ports may be changed as appropriate.

[0079] The basic operation of the second check valve 71 may also be basically similar to that of a known check valve. For example, if the force with which the hydraulic fluid from port 71d pushes the valve disc 71b to the right in FIG. 3 is smaller than the sum of the force with which the hydraulic fluid from port 71e pushes the valve disc 71b to the left in FIG. 3 and the biasing force of spring 71c, the valve disc 71b blocks port 71d, thereby blocking ports 71d and 71e. That is, the second check valve 71 is closed (self-closed). On the other hand, if the former force is greater than the latter force, the valve disc 71b moves away from port 71d, thereby connecting ports 71d and 71e. That is, the second check valve 71 is opened.

[0080] The structure of the flow control valve 63 may basically be similar to various structures, including known structures. For example, in the illustrated example, the flow control valve 63 has a so-called spool-type valve. The flow control valve 63 has a hollow main body 63a and a valve element 63b that is movable within the main body 63a in the left-right direction in FIG. 3. The main body 63a has a port 63c that communicates with the rod-side chamber 29r and a port 63d that communicates with the tank 61. The valve element 63b has two enlarged-diameter portions 63e and 63f that slide within the main body 63a, and a reduced-diameter portion 63h that connects these enlarged-diameter portions and has a smaller diameter than the enlarged-diameter portions. The specific shapes of the components and the positional relationship of the ports may be changed as appropriate.

[0081] The basic operation of the flow control valve 63 may also be basically similar to the operation of a known valve. For example, when one of the two enlarged diameter portions (enlarged diameter portion 63f in the illustrated example) blocks one of the two ports (port 63c in the illustrated example), the two ports are blocked. That is, the flow control valve 63 is closed. When the one enlarged diameter portion (63f) retracts from at least a portion of the one port (63c), the two ports are connected. That is, the flow control valve 63 is opened. The amount by which the one enlarged diameter portion (63f) retracts from the one port (63c) determines the degree of opening, and therefore the flow rate.

[0082] In the following description, the direction of movement of the valve element 71b of the second check valve 71, along which the second check valve 71 moves when it is opened (the right side in FIG. 3), may be referred to as the open side, and the opposite side as the closed side. Similarly, the direction of movement of the valve element 63b of the flow control valve 63, along which the flow control valve 63 moves when it is opened (the right side in FIG. 3), may be referred to as the open side, and the opposite side as the closed side.

[0083] As described above, the second check valve 71 and the flow control valve 63 are connected to each other. Specifically, a connecting member 73 is fixed to the valve element 63b of the flow control valve 63. The connecting member 73 extends from the valve element 63b in the direction of movement of the valve element 63b. The connecting member 73 extends outward from the main body 63a of the flow control valve 63 and is inserted into the main body 71a of the second check valve 71. The tip of the connecting member 73 can be abutted against the main body 71a (the bottom surface of its recess) on the closing side, and can also be moved away from the main body 71a on the opening side.

[0084] When the flow control valve 63 is closed, the connecting member 73 abuts against the valve disc 71b, which is in a position to close the second check valve 71, from the open side of the second check valve 71. This prohibits the second check valve 71 from opening. On the other hand, when the flow control valve 63 is open, the connecting member 73 moves away from the valve disc 71b, which is in a position to close the second check valve 71, to the open side of the second check valve 71. This allows the second check valve 71 to open and close like a normal check valve. In other words, it allows flow from port 71d to port 71e and prohibits flow in the opposite direction.

[0085] In the illustrated example, the open side of the second check valve 71 and the open side of the flow control valve 63 are the same. The second check valve 71 is positioned on the closed side relative to the flow control valve 63. The connecting member 73 extends from the valve body 63b of the flow control valve 63 toward the closed side. This allows the tip of the connecting member 73 to come into contact with the valve body 71b of the second check valve 71 from the open side of the second check valve 71 when the valve body 63b moves toward the closed side.

[0086] Note that the second check valve 71 and the flow control valve 63 can be connected in various ways other than the arrangement and orientation shown in the figure. For example, the connecting member 73 may extend from the valve body 63b toward the open side of the flow control valve 63 and extend out from the main body 63a. The connecting member 73 may then bend toward the closed side of the flow control valve 63 and be inserted into the second check valve 71, whose open side is on the same side as the open side of the flow control valve 63. In this case, the second check valve 71 may be arranged in parallel with the flow control valve 63, for example.

[0087] In the illustrated example, the flow control valve 63 is a so-called overlap type in which the size of the expanded diameter portion 63f is larger than the diameter of the port 63c in the movement direction of the valve element 63b. Therefore, even when the valve element 63b moves from the closed position to the open side, there is an overlap section in which the port 63c remains closed. Furthermore, in the illustrated example, when the valve element 63b leaves the overlap section and the port 63c opens even slightly, the valve element 71b of the second check valve 71 can move to the fully open position.

[0088] Unlike the illustrated example, the length of the overlapping section may be set so that the valve element 71b can move to the fully open position when the port 63c is opened to a certain extent (so that the valve element 71b cannot move to the fully open position before the port 63c is opened to a certain extent). Also, the flow control valve 63 may not have an overlapping section.

[0089] (2.4. Example of injection unit operation) An example of the operation of the injection device 9 will be described below. Here, an example in which the injection device 9 is a fully hydraulic type will be taken as an example. Furthermore, unless otherwise specified, an example in which the hydraulic device 51 has the configuration illustrated in FIG. 2 and the second check valve 71 is connected to the flow control valve 63 as illustrated in FIG. 3 will be taken as an example.

[0090] The injection device 9 performs, for example, low-speed injection, high-speed injection, pressure increase (pressure boosting), and pressure dwell in that order. That is, in the initial stage of injection, the injection device 9 performs low-speed injection by advancing the plunger 23 at a relatively low speed (for example, less than 1 m / s) to prevent air entrainment in the molten metal. Next, the injection device 9 performs high-speed injection by advancing the plunger 23 at a relatively high speed (for example, 1 m / s or more) to fill the molten metal without delaying its solidification. Next, the injection device 9 performs pressure increase (pressure boosting) by using a force in the forward direction of the plunger 23 to raise the molten metal in the space 107 to the casting pressure (final pressure) to prevent sink marks in the molded product. Thereafter, the injection device 9 performs pressure dwell to maintain the casting pressure. Specifically, this is as follows.

[0091] (2.4.1.Low speed injection) Before the start of injection, the injection piston 31 and the booster piston 37 are, for example, at their rearmost positions (the positions shown in FIG. 2). The various valves (55, 56, and 63) are, for example, closed. That is, the flow of hydraulic fluid through the injection cylinder 27 is prohibited.

[0092] When the controller 5 determines that a predetermined injection start condition is satisfied, it controls the hydraulic device 51 (its valve) to allow the flow of hydraulic fluid from the injection accumulator 53A to the head side chamber 29h. In the illustrated example, the introduction of pilot pressure to the first check valve 55 is stopped. The controller 5 also controls the hydraulic device 51 (its valve) to allow the discharge of hydraulic fluid from the rod side chamber 29r. In the illustrated example, the flow control valve 63 is opened. The injection start condition may be, for example, the acquisition of information indicating that the mold 101 has been clamped and that molten metal has been supplied to the sleeve 21.

[0093] When the hydraulic device 51 is controlled as described above, the injection piston 31 starts to move forward due to the pressure in the head side chamber 29h, and thus injection (low speed injection) begins. Also, the flow control valve 63 is opened, allowing the second check valve 71 to open. As a result, the hydraulic fluid discharged from the rod side chamber 29r as the injection piston 31 moves forward can be returned to the head side chamber 29h. The specific function of the injection cylinder 27 during low speed injection is as follows.

[0094] During low-speed injection (either immediately after the start or throughout), the opening (flow rate) of the flow control valve 63 is set small relative to the pressure of the injection accumulator 53A and the cross section of the flow path from the injection accumulator 53A to the head-side chamber 29h. Therefore, although the rod-side chamber 29r communicates with the tank 61 via the flow control valve 63, the pressure in the rod-side chamber 29r cannot immediately reach the tank pressure (for example, approximately atmospheric pressure), and increases due to the pressure applied from the working fluid in the head-side chamber 29h via the injection piston 31.

[0095] At this time, the area of the injection piston 31 that receives pressure from the hydraulic fluid in the head-side chamber 29h is larger than the area that applies pressure to the hydraulic fluid in the rod-side chamber 29r by the difference in the cross-sectional area of the rod 33. Therefore, the pressure in the rod-side chamber 29r can become higher than the pressure in the head-side chamber 29h (or, from another perspective, the injection accumulator 53A). As a result, the second check valve 71 of the runaround circuit 57 is opened, communicating between the rod-side chamber 29r and the head-side chamber 29h.

[0096] As described above, the area of the injection piston 31 that receives pressure from the hydraulic fluid in the head-side chamber 29h is larger than the area that receives pressure from the hydraulic fluid in the rod-side chamber 29r. Therefore, when the second check valve 71 is opened and the rod-side chamber 29r and the head-side chamber 29h are in communication with each other, due to the difference in area, the force that the injection piston 31 receives from the hydraulic fluid in the head-side chamber 29h is larger than the force that the injection piston 31 receives from the hydraulic fluid in the rod-side chamber 29r. As a result, the injection piston 31 moves forward, and ultimately the plunger 23 moves forward.

[0097] When the plunger 23 moves forward, a portion of the hydraulic fluid discharged from the rod-side chamber 29r is returned to the head-side chamber 29h via the second check valve 71 and the first check valve 55. The remainder is discharged to the tank 61 via the flow control valve 63. The controller 5 performs feedback control of the flow control valve 63 so that the speed of the plunger 23 becomes the desired low-speed injection speed.

[0098] (2.4.2.High speed injection) When a predetermined high-speed start condition is satisfied, the controller 5 increases the opening of the flow control valve 63. That is, the controller 5 controls the meter-out circuit so that the speed of the plunger 23 increases. This starts high-speed injection. The high-speed start condition may be, for example, that the position of the plunger 23 reaches a predetermined high-speed switching position.

[0099] When the opening (flow rate) of the flow control valve 63 is set to a certain level during high-speed injection, the pressure in the rod-side chamber 29r tends to approach the tank pressure and drops. As a result, the second check valve 71 closes automatically. In other words, the return flow from the rod-side chamber 29r to the head-side chamber 29h is stopped. The controller 5 performs feedback control of the flow control valve 63 so that the speed of the plunger 23 becomes the desired high-speed injection speed.

[0100] When the space 107 is filled to a certain extent with molten metal, the plunger 23 is decelerated by the reaction force from the filled molten metal, while the injection pressure rises rapidly. The operation of each part is the same as during high-speed injection. However, deceleration control may be performed to reduce the opening of the flow control valve 63. Such deceleration control, for example, can mitigate the impact during filling.

[0101] (2.4.3. Pressure increase and pressure maintenance) The controller 5 controls the hydraulic device 51 to start increasing the pressure when a predetermined condition for starting pressure increase is satisfied. The condition for starting pressure increase may be, for example, that the injection pressure based on the detection value of a pressure sensor (not shown) that detects the pressure in the head side chamber 29h has reached a predetermined pressure, or that the detected position of the plunger 23 detected by a position sensor (not shown) has reached a predetermined position.

[0102] More specifically, the controller 5 controls the boost valve 56 to allow the flow of hydraulic fluid from the boost accumulator 53B to the rear chamber 35b. The boost piston 37 boosts the pressure in the rear chamber 35b and transmits it to the head chamber 29h. The pressure transmitted to the head chamber 29h is higher than the pressure in the injection accumulator 53A. This causes the pressure to be boosted.

[0103] Because the pressure in the head side chamber 29h is higher than the pressure in the injection accumulator 53A, the first check valve 55 closes automatically. However, the first check valve 55 may also be closed by introducing pilot pressure. Closing the first check valve 55 reduces the likelihood that the high pressure in the head side chamber 29h will be applied to the runaround circuit 57.

[0104] From the low-speed injection until the start of pressure increase, the controller 5 performs speed control based on the detection value of the position sensor (detection value of the injection speed), for example. On the other hand, once pressure increase starts, the controller 5 may perform pressure control based on the detection value of the injection pressure. In pressure control, the controller 5 may, for example, feedback control the flow control valve 63 so that the detection value of the injection pressure increases along a predetermined pressure increase curve.

[0105] Thereafter, the injection pressure reaches the casting pressure (final pressure). The controller 5 performs pressure holding to maintain the injection pressure at the casting pressure, for example, by maintaining the same state as during pressure boosting. Thereafter, when the molten metal solidifies, the controller 5 performs operations such as retracting the plunger 23. The controller 5 also accumulates pressure in the injection accumulator 53A and the boosting accumulator 53B at an appropriate time during the molding cycle.

[0106] (3. Variations of injection devices) Other examples of the configuration of the injection device 9 will be described below. Here, only differences from the configuration of the injection device 9 described above will be basically described (the same applies to the drawings). Items not specifically mentioned may be considered to be the same as the configurations described so far, or may be inferred from the configurations described so far. Furthermore, for the sake of convenience, the same reference numerals may be used to refer to configurations that correspond to each other in multiple embodiments, even if there are differences.

[0107] 4 to 5(b) are schematic diagrams showing other examples of the configuration of the injection device 9 (for convenience, referred to as injection devices 9A to 9C). The injection devices 9A to 9C differ from the injection device 9 in the configuration of the pressure boosting mechanism 81 (reference numeral shown in FIG. 2) that boosts the pressure in the head side chamber 29h. Specifically, this is as follows. After explaining the injection devices 9A to 9C, for convenience, only the reference numerals related to the injection device 9 may be used, but unless contradictions arise, the explanation using the reference numerals related to the injection device 9 may be applied to the injection devices 9A to 9C.

[0108] The injection device 9A in Fig. 4 does not have a booster accumulator 53B. The rear chamber 35b of the booster cylinder member 35 is supplied with hydraulic fluid from the injection accumulator 53A. That is, the pressure in the head side chamber 29h is made higher than the pressure in the injection accumulator 53A by the boosting action of the booster piston 37. The second end 59b of the runaround circuit 57 is located closer to the injection accumulator 53A than the booster valve 56.

[0109] In the illustrated example, a portion of the second end 59b side of the reflux flow path 59 of the runaround circuit 57 is shared with a portion of the flow path from the injection accumulator 53A to the booster valve 56. However, such sharing is not required.

[0110] The injection device 9B of FIG. 5(a) does not have a booster cylinder member 35 and a booster piston 37. That is, the injection cylinder 27B is of a so-called single-barrel type. The booster accumulator 53B is capable of supplying hydraulic fluid to the head-side chamber 29h. The pressure at the completion of pressure accumulation in the booster accumulator 53B (or, from another perspective, immediately before the start of pressure increase) is set higher than the pressure at the completion of discharge from the injection accumulator 53A (or, from another perspective, immediately before the start of pressure increase). This enables pressure increase (boosting). Note that the pressure at the completion of pressure accumulation in the booster accumulator 53B may be higher than the pressure at the completion of pressure accumulation in the injection accumulator (or, from another perspective, the pressure immediately before the start of injection).

[0111] 5(b), an injection device 9C is configured to drive a booster piston 37C by an electric motor 75. The electric motor 75 may be a rotary motor or a linear motor. In the former embodiment, an appropriate mechanism (for example, a screw mechanism) for converting the rotation of the electric motor 75 into linear motion (translational motion) may be interposed between the electric motor 75 and the booster piston 37C.

[0112] The electric motor 75 is configured to be able to exert a driving force such that the pressure applied to the head side chamber 29h by the booster piston 37C becomes higher than the pressure at the completion of discharge of the injection accumulator 53A (from another perspective, immediately before the start of boosting). This enables boosting (pressure increase). Note that the electric motor 75 may also be configured to be able to exert a driving force such that the pressure applied to the head side chamber 29h by the booster piston 37C becomes higher than the pressure at the completion of pressure accumulation in the injection accumulator 53A (from another perspective, the pressure immediately before the start of injection).

[0113] In the illustrated example, the diameters of the booster cylinder member 35C and the booster piston 37C are the same as the diameters of the injection cylinder member 29 and the injection piston 31. However, the former may be smaller than the latter. This allows the pressure applied to the head side chamber 29h to be relatively high relative to the driving force generated by the electric motor 75. Furthermore, the cylinder chamber (rear side chamber 35b) on the opposite side of the booster cylinder member 35C from the side communicating with the head side chamber 29h may or may not be filled with hydraulic fluid. The booster cylinder member 35C may be in series with the injection cylinder member 29 (in the illustrated example), or it does not have to be in series.

[0114] Although not specifically shown, a pressure-boosting mechanism that applies a pressure higher than the pressure of the injection accumulator 53A to the head-side chamber 29h may not be provided. That is, in the configuration having the single-barrel injection cylinder 27B shown in FIG. 5(a), the pressure-boosting accumulator 53B may be eliminated. Even in such an embodiment, for example, when high pressure is generated in the head-side chamber 29h due to the inertial force of the hydraulic fluid, the first check valve 55 reduces the likelihood that the pressure will be applied to the runaround circuit 57.

[0115] As can be seen from the pressure intensifying mechanism in Fig. 5(b), the injection device 9 may not be a fully hydraulic type, but may be a hybrid type that combines an electric type and a hydraulic type. In the hybrid type injection device 9, an electric motor may be used to drive the injection piston 31 instead of or in addition to the pressure intensifying mechanism. Such an electric motor may be used, for example, for low-speed injection and / or retraction of the injection piston 31.

[0116] In the hybrid injection device 9, when at least a part of the process of advancing the injection piston 31 (e.g., low-speed injection and high-speed injection) is performed by advancing the injection piston 31 with an electric motor, the hydraulic fluid may be replenished to the head side chamber 29h by a configuration other than the injection accumulator 53A. For example, the hydraulic fluid may be replenished by the pump 65 or the tank 61. An accumulator with a relatively low pressure (e.g., less than 1 MPa) may be used.

[0117] As can be understood from the above, it is also possible to omit the injection accumulator 53A. For example, injection in the narrow sense from the start of injection to before pressure increase may be performed electrically, and pressure increase may be performed by increasing the pressure in the head side chamber 29h electrically or hydraulically. That is, the supply source that supplies hydraulic fluid to the head side chamber 29h may be the pump 65 and / or the tank 61. The first check valve 55 may be provided between such a supply source and the head side chamber 29h. The second end 59b of the runaround circuit 57 may be connected between the supply source and the first check valve 55.

[0118] The run-around circuit 57 may be used when the injection piston 31 is being advanced by the electric motor, instead of or in addition to the step of supplying hydraulic fluid to the head side chamber 29h by the injection accumulator 53A to advance the injection piston 31. In the previous description of the operation of the injection device 9, the run-around circuit 57 was used for low-speed injection, not for high-speed injection. However, the run-around circuit 57 may be used in a manner different from that. For example, the run-around circuit 57 may be used not only for low-speed injection, but also for high-speed injection.

[0119] As can be understood from the above description, the hydraulic device may have a meter-in circuit instead of or in addition to the meter-out circuit (flow control valve 63). In addition, in a hybrid type, it is also possible to not provide both the meter-out circuit and the meter-in circuit.

[0120] (4. Summary of the embodiment) As described above, the injection device 9 has the injection cylinder 27, a supply source (e.g., injection accumulator 53A), a first check valve 55, and a runaround circuit 57. The injection cylinder 27 has a rod 33, an injection piston 31, and an injection cylinder member 29. The rod 33 is connected to the plunger 23 that pushes the molding material into the mold (space 107). The injection piston 31 is fixed to the rod 33. The injection cylinder member 29 houses the injection piston 31. The interior of the injection cylinder member 29 is partitioned by the injection piston 31 into a rod-side chamber 29r on the side where the rod 33 is located, and a head-side chamber 29h on the opposite side. The injection accumulator 53A supplies hydraulic fluid to the head-side chamber 29h. The first check valve 55 allows flow from the injection accumulator 53A side to the head-side chamber 29h side and prohibits flow in the opposite direction. The run-around circuit 57 has a flow path (return flow path 59) that allows hydraulic fluid to flow from the rod-side chamber 29r to the head-side chamber 29h when the injection piston 31 moves toward the rod-side chamber 29r side. The return flow path 59 has a first end 59a connected to the rod-side chamber 29r and a second end 59b connected between the injection accumulator 53A and the first check valve 55.

[0121] Therefore, as described in the overview of the embodiment, for example, when the pressure in the head side chamber 29h becomes higher than the pressure of the supply source (injection accumulator 53A), the likelihood of high pressure being applied to the run-around circuit 57 is reduced. As a result, for example, the pressure resistance of the run-around circuit 57 can be lowered, thereby reducing costs. From another perspective, the need to provide a check valve separate from the first check valve 55 for reducing the pressure applied to the run-around circuit 57 is reduced, thereby reducing costs. Furthermore, for example, by reducing the likelihood of high pressure being applied to the run-around circuit 57, leakage of hydraulic fluid in the run-around circuit 57 can be reduced, improving the accuracy of operation of the injection unit 9 and ultimately improving the quality of molded products.

[0122] When hydraulic fluid flows from the injection accumulator 53A to the head-side chamber 29h, the pressures therebetween are not the same. More specifically, the pressure on the injection accumulator 53A side relative to the first check valve 55 is higher than the pressure on the head-side chamber 29h side relative to the first check valve 55. Therefore, the operating characteristics of the injection cylinder 27 according to the embodiment may differ from those of the prior art (a configuration in which the second end 59b is connected to the head-side chamber 29h side relative to the first check valve 55). This is one of the reasons why it was difficult to arrive at the configuration of the embodiment. However, the applicant has confirmed through experiments that the configuration of the embodiment can achieve operating characteristics similar to those of the conventional configuration.

[0123] The supply source (a component connected to the head side chamber 29h via the first check valve 55) may be the injection accumulator 53A.

[0124] In this case, for example, the first check valve 55 is configured to be able to supply a large flow rate of hydraulic fluid from the injection accumulator 53A to the head side chamber 29h. As a result, for example, the first check valve 55 can allow hydraulic fluid flowing from the rod side chamber 29r to the second end 59b to flow at a large flow rate to the head side chamber 29h via the runaround circuit 57. In other words, the likelihood of an inconvenience such as a reduction in the flow rate of the runaround circuit 57 occurring due to the second end 59b being connected to the head side chamber 29h via the first check valve 55 rather than directly to the head side chamber 29h is reduced.

[0125] The injection device 9 may further include a pressure increasing mechanism 81 (not limited to that shown in FIG. 2, but may be, for example, that shown in FIGS. 4 to 5(b)) that increases the pressure in the head side chamber 29h higher than the pressure in the injection accumulator 53A.

[0126] In this case, for example, there are many occasions when the pressure in the head-side chamber 29h is relatively increased by the pressure boosting mechanism 81. Therefore, the effect of reducing the pressure applied to the run-around circuit 57 by connecting the second end 59b of the run-around circuit 57 between the first check valve 55 and the injection accumulator 53A is effectively achieved.

[0127] The booster mechanism 81 may include a booster cylinder member 35 and a booster piston 37 that slides inside the booster cylinder member 35. The booster cylinder member 35 may include a small-diameter cylinder portion 35x and a large-diameter cylinder portion 35y. The small-diameter cylinder portion 35x communicates with the head-side chamber 29h. The large-diameter cylinder portion 35y is fixed to the small-diameter cylinder portion 35x and has an inner diameter larger than that of the small-diameter cylinder portion 35x. The booster piston 37 may include a small-diameter piston portion 37x and a large-diameter piston portion 37y. The small-diameter piston portion 37x slides inside the small-diameter cylinder portion 35x. The large-diameter piston portion 37y is fixed to the small-diameter piston portion 37x and slides inside the large-diameter cylinder portion 35y.

[0128] In this case, for example, since the boosting action is obtained by the booster piston 37, the pressure of the injection accumulator 53A may be lowered even in an embodiment in which the injection accumulator 53A is used for boosting (FIG. 4). As a result, for example, the pressure applied from the injection accumulator 53A to the runaround circuit 57 is reduced. Also, in an embodiment in which the booster accumulator 53B is provided (FIG. 2), for example, a higher casting pressure can be obtained compared to an embodiment in which the pressure is boosted by the injection accumulator 53A. As a result, for example, the pressure applied to the runaround circuit 57 can be made smaller relative to the magnitude of the casting pressure.

[0129] The pressure-increasing mechanism 81 may have a pressure-increasing accumulator 53B that applies hydraulic pressure to a cylinder chamber (rear chamber 35b) of the large-diameter cylinder portion 35y located on the opposite side of the pressure-increasing piston 37 from the small-diameter cylinder portion 35x (FIG. 2).

[0130] In this case, the pressure in the head-side chamber 29h may become higher than in a configuration in which the boost accumulator 53B is not provided (FIG. 4). Therefore, the effect of reducing the pressure applied to the run-around circuit 57 by connecting the second end 59b of the run-around circuit 57 to the side opposite the head-side chamber 29h with respect to the first check valve 55 is effectively achieved.

[0131] The injection device 9 may have a second check valve 71 and a flow control valve 63 in the flow path (return flow path 59) of the runaround circuit 57. The second check valve 71 may allow flow from the first end 59a side to the second end 59b side and prohibit flow in the opposite direction. The flow control valve 63 may be interposed between the rod-side chamber 29r and the tank 61. The flow control valve 63 may be connected to the second check valve 71 so as to prohibit the second check valve 71 from opening when the flow control valve 63 is closed, and to allow both the closing and opening operations of the second check valve 71 when the flow control valve 63 is open.

[0132] In this case, for example, by reducing the pressure applied to the runaround circuit 57, the pressure resistance of the second check valve 71 can be lowered, resulting in cost reduction. Unlike a normal check valve, the second check valve 71 has a hole (reference number omitted) into which the connecting member 73 is inserted. By reducing the pressure applied to the second check valve 71, the likelihood of hydraulic fluid leaking from the hole is reduced. From another perspective, the need to increase the sealing performance of the connecting member 73 is reduced, thereby reducing the likelihood of increased sliding resistance of the connecting member 73. As a result, the likelihood of a decrease in responsiveness of the flow control valve 63 due to the sliding resistance of the connecting member 73 is reduced. These factors improve the operational accuracy of the injection unit 9, and ultimately improve the quality of molded products.

[0133] From the viewpoint of improving the accuracy of control of the flow rate discharged from the rod side chamber 29r, the flow control valve 63 is disposed near the port in the discharge flow path 69 from the port of the rod side chamber 29r to the tank 61. The port is usually located on the tip side of the injection cylinder 27, and therefore the flow control valve 63 is disposed near the tip of the injection cylinder 27. The second check valve 71 is connected to the flow control valve 63, and therefore is disposed near the flow control valve 63 and therefore near the tip of the injection cylinder 27. In addition, the second end 59b of the runaround circuit 57 is (indirectly) connected to the head side chamber 29h, and therefore is disposed near the rear end of the injection cylinder 27, for example. As a result, the return flow path 59 of the runaround circuit 57 tends to have a long section from the second check valve 71 to the second end 59b. From another viewpoint, it is difficult to reduce the pressure applied to the return flow path 59 by the second check valve 71. From this perspective, the effect of reducing the pressure applied to the runaround circuit 57 by the first check valve 55 is also effective.

[0134] The injection device 9 may have a second check valve 71 in the flow path (return flow path 59) of the runaround circuit 57, which allows flow from the first end 59a to the second end 59b and prohibits flow in the opposite direction. At least a portion of the return flow path 59 on the second end 59b side of the second check valve 71 may be composed of at least one of a pipe and a hose.

[0135] In this case, costs can be reduced compared to when the return flow path 59 is formed by a block, for example. Because the pressure applied to the return flow path 59 can be reduced, pipes and / or hoses having lower pressure resistance than blocks can be selected as the members forming the return flow path 59. As described above, the return flow path 59 typically extends from the front end side of the injection cylinder 27 to the rear end side of the injection cylinder 27 and tends to be relatively long. Forming such a return flow path 59 by pipes and / or hoses reduces the overall size of the hydraulic device 51 and also has the effect of reducing costs.

[0136] The injection device 9 may further include a pump line 67 for allowing hydraulic fluid to flow from the pump 65 to the injection accumulator 53A. The flow path (return flow path 59) of the run-around circuit 57 is not shared with the pump line 67.

[0137] In this case, for example, it is easy to simplify the path of the reflux flow path 59, and therefore it is easy to shorten the length of the reflux flow path 59. As a result, for example, it is possible to reduce the amount of hydraulic fluid required for the run-around circuit 57. Also, the pressure in the rod-side chamber 29r is more easily transmitted to the head-side chamber 29h. As a result, it is expected that the responsiveness of the injection speed (i.e., the accuracy of control) will improve, and in turn, the quality of the molded product will improve.

[0138] There is no need for a valve that is controlled during the molding cycle to be interposed between the second end 59b of the run-around circuit 57 and the supply source (injection accumulator 53A).

[0139] In this case, for example, the pressure in the injection accumulator 53A and the pressure in the run-around circuit 57 tend to be equal. As a result, the possibility of unintended pressure fluctuations occurring due to the pressure difference between the two is reduced. In other words, the accuracy of control of the injection cylinder 27 is improved.

[0140] In the above embodiment, the die-casting machine 1 is an example of a molding machine. The metal mold 101 is an example of a mold. The molten metal is an example of a molding material. The injection accumulator 53A is an example of a supply source.

[0141] The present invention is not limited to the above-described exemplary embodiments, and may be implemented in various forms.

[0142] The molding machine is not limited to a die-casting machine. For example, the molding machine may be another metal molding machine or an injection molding machine for molding resin. In the injection molding machine, the plunger may be screw-shaped. Furthermore, the molding machine is not limited to a horizontal clamping / horizontal injection type, and may be, for example, a vertical clamping / vertical injection type, a vertical clamping / horizontal injection type, or a horizontal clamping / vertical injection type. The die-casting machine is not limited to a cold chamber machine, and may be, for example, a hot chamber machine, or a combination of a cold chamber machine and a hot chamber machine. [Explanation of symbols]

[0143] 1...die-casting machine (molding machine), 9...injection device, 29...injection cylinder member, 29...rod side chamber, 29h...head side chamber, 31...injection piston, 33...rod, 53A...injection accumulator (supply source), 55...first check valve, 57...runaround circuit, 59...reflux flow path (flow path of runaround circuit), 59a...first end (of runaround circuit), 59b...second end (of runaround circuit).

Claims

1. an injection cylinder including a rod connected to a plunger that pushes molding material into a mold, an injection piston fixed to the rod, and an injection cylinder member that houses the injection piston, the interior of the injection cylinder member being divided by the injection piston into a rod-side chamber on the side where the rod is located and a head-side chamber on the opposite side; a supply source that supplies hydraulic fluid to the head side chamber; a first check valve that allows a flow from the supply source side to the head-side chamber side and prohibits a flow in the opposite direction; a run-around circuit including a flow path that allows hydraulic fluid to flow from the rod-side chamber to the head-side chamber when the injection piston moves toward the rod-side chamber; It has The flow path is a first end connected to the rod side chamber; a second end connected between the supply and the first check valve. Injection device.

2. the source is an injection accumulator The injection device according to claim 1 .

3. The injection accumulator further includes a pressure increasing mechanism that increases the pressure in the head side chamber to a level higher than the pressure in the injection accumulator. The injection device according to claim 2 .

4. The pressure increasing mechanism is a booster cylinder member; a booster piston that slides inside the booster cylinder member, The booster cylinder member is a small diameter cylinder portion communicating with the head side chamber; a large-diameter cylinder portion fixed to the small-diameter cylinder portion and having an inner diameter larger than an inner diameter of the small-diameter cylinder portion, The booster piston is a small diameter piston portion that slides on the small diameter cylinder portion; a large-diameter piston portion fixed to the small-diameter piston portion and sliding on the large-diameter cylinder portion; The injection device according to claim 3 .

5. The pressure-increasing mechanism has a pressure-increasing accumulator that applies hydraulic pressure to a cylinder chamber of the large-diameter cylinder portion that is located on the opposite side of the pressure-increasing piston from the small-diameter cylinder portion.

5. The injection device according to claim 4.

6. a second check valve in the flow path of the runaround circuit that allows flow from the first end to the second end and prohibits flow in the opposite direction; a flow control valve interposed between the rod side chamber and a tank; It has The flow control valve is connected to the second check valve so as to prohibit the second check valve from opening when the flow control valve is closed, and to allow both the closing and opening operations of the second check valve when the flow control valve is open. The injection device according to claim 1 .

7. a second check valve is provided in the flow path of the runaround circuit to allow flow from the first end to the second end and to prohibit flow in the opposite direction; At least a portion of the flow path on the second end side of the second check valve is formed by at least one of a pipe and a hose. The injection device according to claim 1 .

8. a pump line for flowing hydraulic fluid from the pump to the injection accumulator; The flow path of the runaround circuit is not shared with the pump line. The injection device according to claim 2 .

9. No valve that is controlled during the molding cycle is interposed between the second end and the supply source. The injection device according to claim 1 .

10. The injection device according to claim 1 ; a mold clamping device that clamps the mold; The molding machine has:

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