Surge pressure absorption device, hydraulic device of surge pressure absorption device, molding machine, and hydraulic pressure cylinder

Abstract

To improve responsiveness related to surge pressure absorption.SOLUTION: A surge pressure absorption device 2 includes a check valve 51 connected to a hydraulic cylinder 43. In the cylinder 43, a rod 49 is fixed to an advancing / retreating member 41 capable of advancing into a metal mold 101 and retreating in the opposite direction. A piston 47 is fixed to the rod 49. A cylinder member 45 stores the piston 47. The inside of the cylinder member 45 is partitioned by the piston 47 into a rod side chamber 45r where the rod 49 is positioned and a head side chamber 45h on the opposite side. In the process that the advancing / retreating member 41 retreats by the pressure of molten metal 109 in the metal mold 101, and the piston 47 moves from a rod side chamber 45r side to a head side chamber 45h side, the check valve 51 permits the flow from the head side chamber 45h to the rod side chamber 45r, and prohibits the flow in the opposite direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a surge pressure absorbing device, a hydraulic device for the surge pressure absorbing device, a molding machine including the surge pressure absorbing device, and a hydraulic cylinder that can be used for the surge pressure absorbing device. The molding machine is, for example, a die casting machine that molds metal or an injection molding machine that molds resin. [Background technology]

[0002] It is known that so-called surge pressure occurs in molding machines that produce molded products by injecting molding material (e.g., molten metal) into a mold cavity by pushing the molding material (e.g., molten metal) in a sleeve that communicates with the cavity using a plunger. Surge pressure is an instantaneous and relatively large pressure that occurs when the molding material spreads throughout almost the entire cavity and has nowhere to escape (when filling is almost complete). If the surge pressure is too large, for example, so-called burrs are formed. Burrs are parts that are formed when the molding material protrudes into the periphery of the cavity (parts that were not intended to be formed).

[0003] Patent Document 1 discloses a technology relating to local pressurization in which molding material filled in a cavity is pressurized by a squeeze pin. In Patent Document 1, the squeeze pin is driven by a hydraulic (liquid pressure) cylinder. Patent Document 1 proposes performing local pressurization by advancing the squeeze pin with a first pressure, and then performing local pressurization by advancing the squeeze pin with a second pressure higher than the first pressure (performing two-stage local pressurization).

[0004] Patent Document 2 proposes a technology for reducing surge pressure using a local pressurizing device for local pressurization. Specifically, in Patent Document 2, before the molding material is injected into the cavity, a pressurizing member (squeeze pin) is made to wait at the forward limit. At this time, a first pressure is applied by an accumulator to a hydraulic cylinder that drives the pressurizing member. Thereafter, when the molding material is injected and reaches the pressurizing member, the pressurizing member retreats due to the pressure of the molding material. This absorbs the surge pressure. Then, a second pressure higher than the first pressure is applied to the cylinder. This causes the pressurizing member to advance and perform local pressurization.

[0005] Patent Documents 3 and 4 disclose a flow path connecting two cylinder chambers (a rod side chamber and a head side chamber) in a hydraulic cylinder that drives a pressurizing plunger (squeeze pin), and a valve provided in the flow path. This flow path is used to bleed gas (air) from the cylinder.

[0006] Patent documents 5 to 7 disclose a technique in which a die (a die separate from the die that constitutes the cavity) is incorporated into the cavity and a hydraulic cylinder for driving the die. These documents disclose a flow path that connects the front cylinder chamber (rod side chamber) and the rear cylinder chamber (head side chamber) for cooling and air bleeding, and a valve for opening and closing the flow path.

[0007] More specifically, for example, FIG. 3 of Patent Document 5 discloses a check valve that allows flow from the head side chamber to the rod side chamber and prohibits flow in the opposite direction. An orifice and a relief valve are interposed between the head side chamber and the check valve. When hydraulic oil is supplied to the head side chamber and the piston reaches its forward limit (the driving limit on the rod side chamber side), the pressure in the head side chamber increases and the relief valve opens. The hydraulic oil in the head side chamber flows to the tank via the check valve and the rod side chamber in this order. By exchanging the hydraulic oil in this way, the cylinder is cooled and air is bled.

[0008] Patent Document 6 discloses a control valve built into a piston. The control valve includes a check valve that allows flow from the head side chamber to the rod side chamber and prohibits flow in the opposite direction. However, the control valve includes another check valve that is connected in series and in the opposite direction to the check valve, and is configured to prohibit flow in either direction unless the piston reaches the rearward limit (the drive limit on the head side chamber side).

[0009] Patent Document 6 discloses a control valve built into a piston. The control valve is not opened by the pressure in the rod side chamber or the head side chamber, but is configured to open when the piston reaches its forward or backward limit.

[0010] Patent Document 8 discloses an air cylinder capable of communicating between a rod side chamber and a head side chamber. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2016-196009 A [Patent Document 2] Patent No. 7137729 [Patent Document 3] JP 2021-20224 A [Patent Document 4] International Publication No. 2021 / 14707 [Patent Document 5] JP 2002-31101 A [Patent Document 6] JP 2006-207792 A [Patent Document 7] JP 2013-7407 A [Patent Document 8] Japanese Utility Model Application Publication No. 58-76805 Summary of the Invention [Problem to be solved by the invention]

[0012] There is a need for a surge pressure absorbing device that can improve the responsiveness in absorbing surge pressure, a hydraulic device and molding machine for the surge pressure absorbing device, and a hydraulic cylinder that can be used in the surge pressure absorbing device. [Means for solving the problem]

[0013] A surge pressure absorption device according to one embodiment of the present disclosure comprises a rod fixed to a forward / backward moving member capable of advancing into a mold and retracting to the opposite side, a piston fixed to the rod, and a cylinder member housing the piston, the interior of the cylinder member being a hydraulic cylinder partitioned by the piston into a rod side chamber in which the rod is located and a head side chamber on the opposite side, and a check valve that allows flow from the head side chamber to the rod side chamber and prohibits flow in the opposite direction as the piston moves from the rod side chamber to the head side chamber as the forward / backward moving member retracts due to the pressure of the molding material in the mold.

[0014] A hydraulic device of a surge pressure absorption device according to one embodiment of the present disclosure has a rod fixed to a forward / backward member capable of advancing into a mold and retracting to the opposite side, a piston fixed to the rod, and a cylinder member housing the piston, the interior of the cylinder member being connected to a hydraulic cylinder partitioned by the piston into a rod side chamber in which the rod is located and a head side chamber on the opposite side, and has a runaround circuit that connects the rod side chamber and the head side chamber when the forward / backward member is retracted by the pressure of the molding material in the mold and the piston moves from the rod side chamber to the head side chamber.

[0015] A molding machine according to one aspect of the present disclosure includes the surge pressure absorbing device, a clamping device that holds the mold, and an injection device that injects molding material into the mold.

[0016] A hydraulic cylinder according to one aspect of the present disclosure includes a cylinder member, a piston housed in the cylinder member and dividing the interior of the cylinder member into a rod side chamber and a head side chamber, a rod fixed to the piston and extending to the outside of the cylinder member via the rod side chamber, and a check valve included in the piston that allows flow from the head side chamber to the rod side chamber and prohibits flow in the opposite direction as the piston moves from the rod side chamber side to the head side chamber side. Effect of the Invention

[0017] According to the above configuration, for example, it is possible to improve the responsiveness in absorbing surge pressure. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1(a) is a schematic diagram for explaining an overview of a surge pressure absorbing device according to an embodiment, and FIG. 1(b) is an enlarged view of a region Ib in FIG. 1(a). [Diagram 2] FIG. 2(a) is a schematic diagram showing a continuation of the operation of FIG. 1(a), and FIG. 2(b) is an enlarged view of region IIb of FIG. 2(a). [Diagram 3] FIG. 2 is a schematic diagram showing the configuration of a main part of the surge pressure absorbing device of FIG. 1. [Figure 4] FIG. 2 is a side view showing the configuration of a main part of the die casting machine according to the embodiment. [Diagram 5] FIG. 4 is a schematic diagram showing a state in which the surge pressure absorbing device is absorbing surge pressure. [Figure 6] Schematic diagram showing a continuation of Figure 5. [Figure 7] Schematic diagram showing a continuation of Figure 6. [Figure 8] Schematic diagram showing a continuation of Figure 7. [Figure 9] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] (Overview of surge pressure absorbing device according to embodiment) 1(a) to 2(b) are schematic diagrams showing an overview of the operation of a surge pressure absorbing device 2 (hereinafter, sometimes simply referred to as "the absorbing device 2") and an injection device 9 according to an embodiment.

[0020] Figures 1(a) and 2(a) show the absorber 2 and the injection unit 9 diagrammatically and at different times during the molding cycle (more specifically during the injection cycle). Figure 1(b) is an enlarged view of region Ib in Figure 1(a). Figure 2(b) is an enlarged view of region IIb in Figure 2(a).

[0021] 1(a) shows a state in which an injection process is being performed in which a molding material (for example, molten metal 109, which is a molten metal) is injected into the interior of a mold 101. In the injection process, as shown by arrow a1, a plunger 21 (injection plunger) advances toward the mold 101, thereby pushing out the molten metal 109 in the sleeve 19 into the interior of the mold 101 (cavity 107).

[0022] FIG. 2(a) shows the state after FIG. 1(a). As the injection process progresses, the molten metal 109 spreads throughout almost the entire cavity 107. FIG. 2(a) shows such a state. In the description of the embodiment, the completion of filling may be said to be when such a state is reached. When filling is completed, the plunger 21 pushes the molten metal 109, which has nowhere to escape, and the pressure of the molten metal 109 increases. At this time, a so-called surge pressure accompanied by a temporary and sudden pressure increase may occur.

[0023] Here, in this embodiment, there are provided an advancing / retreating member 41 that can advance into the cavity 107 and retreat to the opposite side, and a cylinder 43 fixed to the advancing / retreating member 41. The cylinder 43 is a hydraulic cylinder (for example, a hydraulic cylinder).

[0024] 1(a) and 1(b), before filling is completed (or, from another point of view, before the molten metal reaches the advancing / retreating member 41), the advancing / retreating member 41 waits at an initial position (for example, the forward limit) forward of the retreat limit (on the cavity 107 side). Then, when the molten metal 109 reaches the position of the advancing / retreating member 41 and the force of the molten metal 109 pushing the advancing / retreating member 41 backward exceeds a certain magnitude, the advancing / retreating member 41 retreats as shown by arrow a2 (FIG. 2(a)) and arrow a3 (FIG. 2(b)). Note that the advancing / retreating member 41 may or may not reach the retreat limit.

[0025] The force caused by the retreat of the advancing / retreating member 41 is transmitted to the cylinder 43, which drives the cylinder 43. From another point of view, the advancing / retreating member 41 retreats while receiving a force resisting the retreat from the cylinder 43. Thereby, for example, a certain degree of pressure is applied to the molten metal 109, and at least a part of the surge pressure is absorbed.

[0026] The absorbing device 2 can then perform so-called local pressurization by advancing the advancing / retracting member 41. However, the absorbing device 2 may be used only to absorb the surge pressure without performing such local pressurization. In the description of the embodiment, the mode in which local pressurization is performed will be mainly taken as an example.

[0027] Fig. 3 is a schematic diagram showing the configuration of the main part of the absorbing device 2. Note that, with respect to the cylinder 43, the left-right direction in Fig. 3 is the same as the left-right direction in Fig. 1(a). Therefore, the advancing and retracting member 41 is located on the left side of the cylinder 43 in Fig. 3.

[0028] The cylinder 43 includes the following components. A rod 49 fixed to the advancing / retreating member 41. A piston 47 fixed to the rod 49. A cylinder member 45 that houses the piston 47. The inside of the cylinder member 45 is divided by the piston 47 into a rod side chamber 45r in which the rod 49 is located, and a head side chamber 45h on the opposite side. The rod 49 extends to the outside of the cylinder member 45 via the rod side chamber 45r, and its tip side is fixed to the advancing / retreating member 41.

[0029] The term "fixed" may be interpreted broadly as long as no contradiction occurs. For example, the two parts may be fixed by integrally forming them from the same material, or by making them separately and connecting them with screws or the like. Other parts may be interposed between the two. In the following description, the movement of the piston 47 toward the rod side chamber 45r may be referred to as "forward movement," and the movement in the opposite direction may be referred to as "rearward movement."

[0030] When the advancing / retreating member 41 retreats due to the pressure of the molten metal filled in the cavity 107, the piston 47 also retreats. That is, the volume of the head side chamber 45h is reduced. At this time, the hydraulic fluid may be discharged from the head side chamber 45h. From another perspective, when the piston 47 retreats, the volume of the rod side chamber 45r is expanded. At this time, the hydraulic fluid may be supplied to the rod side chamber 45r.

[0031] The destination of the working fluid from the head side chamber 45h is arbitrary. In the illustrated example, the accumulator 65 is connected to the head side chamber 45h. Therefore, for example, when the pressure in the head side chamber 45h exceeds the pressure of the accumulator 65, the working fluid in the head side chamber 45h flows into the accumulator 65. From another point of view, the pressure in the head side chamber 45h is generally maintained at the pressure of the accumulator 65. Thereby, for example, the absorption device 2 can apply a certain degree of pressure to the molten metal while absorbing the surge pressure.

[0032] For example, when the volume of the flow path between the head side chamber 45h and the accumulator 65 is relatively large and the amount of working fluid discharged from the head side chamber 45h is relatively small, the working fluid in the head side chamber 45h does not necessarily reach the accumulator 65. However, in this disclosure, for convenience, even in the above case, it may be expressed as the working fluid in the head side chamber 45h flowing into the accumulator 65. The same applies to the flow of fluid in other parts in the molding machine.

[0033] The absorbing device 2 may have a check valve 51 that allows flow from the head side chamber 45h to the rod side chamber 45r and prohibits flow in the opposite direction while the advancing / retracting member 41 and the piston 47 are moving backward (in other words, at a midway position) due to the pressure of the molten metal. In this case, when the pressure in the head side chamber 45h becomes larger than the pressure in the rod side chamber 45r by a certain degree (which may be approximately 0), the working fluid in the head side chamber 45h flows into the rod side chamber 45r. The check valve 51 (or, from another point of view, the flow path 61 including the check valve 51) may be provided at any position. In the illustrated example, the check valve 51 (flow path 61) is provided in the piston 47.

[0034] The absorbing device 2 may have a run-around circuit 53 that communicates the head side chamber 45h and the rod side chamber 45r when the advancing / retracting member 41 and the piston 47 move backward due to the pressure of the molten metal. In this case, when the pressure in the head side chamber 45h becomes larger than the pressure in the rod side chamber 45r, the hydraulic fluid in the head side chamber 45h flows into the rod side chamber 45r. The specific configuration of the run-around circuit 53 is arbitrary. In the illustrated example, the switching valve 55 is in the neutral position, and the head side chamber 45h, the rod side chamber 45r, and the pump 57 (an example of a hydraulic pressure source) are mutually connected to configure the run-around circuit 53.

[0035] The area of ​​the cross section (cross section perpendicular to the axis) of the head side chamber 45h is the area of ​​the cross section of the rod 49, and is larger than the area of ​​the cross section of the rod side chamber 45r. Therefore, when the piston 47 retracts, the amount of hydraulic fluid discharged from the head side chamber 45h is larger than the amount of hydraulic fluid supplied to the rod side chamber 45r. The difference flows from the head side chamber 45h to the accumulator 65, for example, as described above.

[0036] By providing the check valve 51 and / or the run-around circuit 53, the absorber 2 can respond quickly to a surge pressure, which is an instantaneous pressure fluctuation. More specifically, the following is true.

[0037] Although not particularly shown, a comparative example is one in which the check valve 51 and the runaround circuit 53 are not provided and the rod side chamber 45r is connected to a tank 59 (FIG. 5). In this example, when the piston 47 retracts, the rod side chamber 45r, whose volume increases, draws in the working fluid from the tank 59 due to negative pressure. In this case, the resistance generated in the rod side chamber 45r with respect to the retraction of the piston 47 becomes large.

[0038] On the other hand, in the case where the check valve 51 and / or the run-around circuit 53 are provided, the working fluid is supplied to the rod side chamber 45r by the pressure in the head side chamber 45h that increases with the retraction of the piston 47. As a result, the piston 47 retracts more easily than in the comparative example. As a result, the surge pressure, which is an instantaneous pressure fluctuation, can be easily released to the absorber 2.

[0039] The flow path 61 including the check valve 51 can be regarded as a type of run-around circuit. The run-around circuit 53 can be said to be a circuit that connects the rod side chamber 45r and the head side chamber 45h separately from the flow path 61. In the illustrated example, both the check valve 51 (flow path 61) and the run-around circuit 53 are provided. However, only one of them may be provided. For example, the run-around circuit 53 does not have to be provided.

[0040] The above is an outline of the embodiment. The embodiment will be described below in the following order. 1. Die casting machine (Fig. 4) 1.1. Die casting machines in general 1.2. Machine body 1.3.Control device 1.4.Other configurations of die casting machines 2. Moving parts (Fig. 1(b)) 3. Absorber cylinder and check valve (Fig. 3) 3.1. Operation of Cylinder and Check Valve 3.2.Cylinder structure 3.3. Check valve configuration 4. Hydraulic system of the absorber (Figs. 5 to 8) 4.1. Configuration from Cylinder to Accumulator 4.2. Configuration from pump and tank to cylinder 4.3.Other configurations of hydraulic devices 5. Operation of the injection unit (Figure 9) 6. Operation of the absorber 6.1. State before surge pressure absorption (Fig. 5) 6.2. Surge pressure absorption operation (Fig. 5) 6.3. Operation related to local pressure application (Fig. 6) 6.4. Spray-related operations (Fig. 7) 6.5. Preparation for absorbing surge pressure (Fig. 8) 7. Summary of the embodiment

[0041] (1. Die casting machine) (1.1. Die casting machines in general) Fig. 4 is a side view (including a cross-sectional view in part) showing the configuration of the main part of a die-casting machine DC (an example of a molding machine) according to an embodiment. For convenience, in the description given with reference to Fig. 4, the left side of Fig. 4 may be referred to as the front, and the right side of Fig. 4 may be referred to as the rear.

[0042] The die-casting machine DC with a mold has a mold (mold 101), a reciprocating member 41, and a die-casting machine 1 (also an example of a molding machine) that holds the mold 101. The die-casting machine 1 has a machine body 3 that performs mechanical operations, and a control device 5 that controls the machine body 3. The die-casting machine DC with a mold or the die-casting machine 1 (or the machine body 3) has the absorbing device 2 (FIG. 1(a)) already described. The configurations and operations of the components other than the absorbing device 2 may be publicly known or may be new, in other words, may be in various forms. Note that explanations of configurations and operations that may be publicly known will be omitted as appropriate.

[0043] As already mentioned, the die-casting machine 1 manufactures a product (molded product, die-cast product) made of solidified molding material by injecting (filling) the molten molding material into the cavity 107. The molding material is, for example, a metal such as aluminum. Note that instead of the molten molding material, a molding material in a solid-liquid coexistence state (semi-solidified state or semi-molten state) may be injected into the cavity 107.

[0044] The mold 101 has, for example, a fixed mold 103 and a movable mold 105 facing the fixed mold 103. The main part of the cavity 107 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 facing the fixed mold 103 (mold opening / closing direction). The mold opening / closing direction is, for example, a horizontal direction. In FIG. 4 and the like, for convenience, the cross section of the fixed mold 103 or the movable mold 105 is shown with one type of hatching. However, these molds may be of a direct engraving type or a nesting type. In addition, the fixed mold 103 and / or the movable mold 105 may include a die base.

[0045] (1.2. Machine body) The machine main body 3 includes, for example, a clamping device 7 that opens, closes, and clamps the mold 101, an injection device 9 that injects molten metal into the cavity 107, and an extrusion device (not shown) that pushes the product formed by solidifying the molten metal out of the fixed mold 103 or the movable mold 105.

[0046] The mold clamping device 7 has, for example, a base 11, a fixed die plate 13 fixed on the base 11, a movable die plate 15 movable on the base 11 in the mold opening / closing direction, and a plurality of (for example, four) tie bars 17 inserted through these die plates. The fixed die plate 13 and the movable die plate 15 face each other in the mold opening / closing direction. The fixed die plate 13 holds a fixed die 103 on a surface facing the movable die plate 15. The movable die plate 15 holds a movable die 105 on a surface facing the fixed die plate 13. The mold 101 is opened and closed by the movement of the movable die plate 15 in the mold opening / closing direction. In addition, when the tie bars 17 are extended in a mold closed state, a mold clamping force according to the amount of extension is applied to the mold 101.

[0047] The injection device 9 is located behind the fixed die plate 13 (on the opposite side to the movable die plate 15). As already mentioned, the injection device 9 has a sleeve 19 that communicates with the cavity 107, a plunger 21 that pushes the molten metal in the sleeve 19 into the cavity 107, and a drive unit 23 that drives the plunger 21. Note that since the sleeve 19 and the plunger 21 can be regarded as consumables, only the drive unit 23 may be regarded as the injection device.

[0048] The drive system of the drive unit 23 may be, for example, a hydraulic system (e.g., hydraulic), electric system, or hybrid system (a combination of hydraulic and electric systems). Fig. 1(a) illustrates a hydraulic drive unit 23. That is, the drive unit 23 has a hydraulic cylinder (e.g., injection cylinder) connected to the plunger 21, and a hydraulic device (not shown) that supplies a hydraulic fluid (e.g., hydraulic oil) to the injection cylinder.

[0049] (1.3. Control Device) The control device 5 may be configured to include, for example, a computer, although not particularly shown. The computer may be configured to include, for example, a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an external storage device (e.g., a hard disk drive (HDD) or a solid state drive (SSD)), although not particularly shown. The CPU executes a program stored in the ROM and / or the external storage device, thereby constructing various functional units that perform various calculations (including control). The control device 5 may also include a logic circuit that executes a certain operation, may include a power supply circuit, or may be conceptualized to include a driver. The control device 5 may be integrated in one place in terms of hardware, or may be distributed to multiple places.

[0050] In addition, when focusing on each device included in the die casting machine 1, the control device 5 may be regarded as a control device for that device. For example, the control device 5 may be regarded as a control device for the absorbing device 2.

[0051] In the description of the present embodiment, the operation of the die casting machine 1 (the absorbing device 2) may basically be realized by the control of the control device 5. Therefore, for example, the operations described with reference to Figs. 1(a) to 2(b) and the operations described with reference to Figs. 5 to 8 described later may be realized by the control of the control device 5 unless otherwise specified. In the description of the embodiment, for convenience, various operations may be described without mentioning the points controlled by the control device 5. Note that some or all of the operations realized by the control of the control device 5 may be realized by an operator operating an input device (not shown) of the die casting machine 1, or may be realized manually.

[0052] (1.4. Other configurations of the die casting machine) The die-casting machine DC (or the die-casting machine 1 or the absorbing device 2) may have various sensors. The control device 5 may control each part based on the detection values ​​of the various sensors.

[0053] Examples of such sensors are as follows. For example, although not shown, a position sensor that detects the position of the plunger 21 and / or a sensor that detects the driving force of the driving unit 23 may be provided. Since the velocity can be obtained by differentiating the position, the position sensor may be considered as a velocity sensor. For example, in an embodiment in which the driving unit 23 has an injection cylinder, a pressure sensor that detects the pressure of the hydraulic fluid may be used as the sensor that detects the driving force of the driving unit 23.

[0054] The sensor that detects the position of the plunger 21 is used, for example, to control the injection speed (in other words, the speed of the plunger 21). The sensor that detects the driving force of the drive unit 23 is used to control the injection pressure (in other words, the pressure that the plunger 21 applies to the molding material). However, as will be described later, in this embodiment, the pressure of the molding material may be set to a desired pressure by the absorbing device 2 used for local pressurization, and control of the injection pressure is not essential.

[0055] (2. Moving parts) The die-casting machine DC (or the die-casting machine 1 or the absorbing device 2) may have one or more advancing and retracting members 41 (FIGS. 1(a) to 2(b)). In an embodiment in which a plurality of advancing and retracting members 41 are provided, for example, surge pressure can be absorbed at various positions of the die 101, reducing the likelihood of flash formation. In addition, in a case in which the absorbing device 2 is used for localized pressurization, it becomes easier to apply pressure uniformly to the molten metal in the die 101. However, in the following explanation, for convenience, the explanation may focus on one advancing and retracting member 41 unless otherwise specified.

[0056] 1(b), the shape of the advancing / retreating member 41 may be generally pin-shaped with the advancing / retreating direction as the longitudinal direction (as shown in the example), or it may not be pin-shaped. An example of the latter is a block shape with a diameter larger than the length of the advancing / retreating member 41 in the advancing / retreating direction. The shape of the cross section (cross section perpendicular to the advancing / retreating direction) of the advancing / retreating member 41 may be circular or may be a shape other than circular. The dimensions of the advancing / retreating member 41 are also arbitrary.

[0057] The advancing / retreating member 41 may be disposed in the fixed mold 103 (as shown in the example) or in the movable mold 105. In the description of this embodiment, for convenience, the description may be given on the premise that the advancing / retreating member 41 is disposed in the fixed mold 103.

[0058] For example, a part or the whole of the advancing / retreating member 41 may slide (or from another point of view, come into contact with) the die (the fixed die 103 or the movable die 105). The rear end portion of the advancing / retreating member 41 (the portion connected to the cylinder 43) may be located outside the die, or the entirety of the advancing / retreating member 41 may be located inside the die. An example of the latter is a mode in which the rear end portion of the advancing / retreating member 41 is located in a space defined by a die base (not shown).

[0059] The advancing / retreating direction of the advancing / retreating member 41 may be an appropriate direction. For example, the advancing / retreating direction may be the mold opening / closing direction (the left-right direction in FIG. 1(b)), or may be a direction intersecting (perpendicular or inclined) the mold opening / closing direction. However, if the advancing / retreating direction is the mold opening / closing direction, the advancing / retreating member 41 can be separated from the molded product, for example, by the action of peeling the molded product off from the mold in which the advancing / retreating member 41 is placed.

[0060] The position of the advancing / retreating member 41 relative to the cavity 107 may be set appropriately. For example, as shown in Fig. 1(a) or 1(b), the cavity 107 has a product portion 107a having a shape corresponding to the product shape, a runner 107e that guides the molten metal from the sleeve 19 to the product portion 107a, and an overflow 107b into which excess molten metal flows. The advancing / retreating member 41 may be located on the inner surface of any of these spaces.

[0061] 1(a), the advancing / retreating member 41 is exposed from the inner surface of the overflow 107b into the cavity 107. In addition, in the example of FIG. 1(b), the fixed mold 103 has a recess 107c on the surface facing the movable mold 105, into which the tip portion of the advancing / retreating member 41 is inserted and removed. Of course, the fixed mold 103 does not have to have such a recess 107c.

[0062] In the following description, unless otherwise specified, the case where the advancing / retreating member 41 is located at the overflow 107b may be taken as an example. In this case, the time when the molding material reaches the advancing / retreating member 41 and the time when the surge pressure occurs are closer than in the case where the advancing / retreating member 41 is located at another part of the cavity 107. For convenience of explanation, the two times may not be distinguished.

[0063] The forward and backward limits of the advancing and retreating member 41 may be determined, for example, by providing a member or portion (stopper) on the die 101 or the like against which the advancing and retreating member 41 abuts when the advancing and retreating member 41 advances or retreats, or may be determined by the drive limit of the cylinder 43. In the description of the embodiment, no particular distinction is made as to whether the drive limit of the advancing and retreating member 41 is determined by the advancing and retreating member 41 or the cylinder 43. Unless otherwise specified, or unless a contradiction occurs, the terms drive limit, forward limit, and backward limit of the advancing and retreating member 41 and drive limit, forward limit, and backward limit of the piston 47 may be interchangeable. In addition, illustrations of members that determine the forward and backward limits are omitted.

[0064] (3. Absorber cylinder and check valve) (3.1. Operation of Cylinder and Check Valve) The operation of the advancing / retreating member 41 when it retreats due to the pressure of the molten metal 109 has already been described with reference to Fig. 3. In addition, for example, the cylinder 43 and the check valve 51 can perform the following operations by supplying hydraulic fluid through ports 45a and 45b (Fig. 3) of the cylinder member 45.

[0065] When an equal hydraulic pressure is applied to both the head side chamber 45h and the rod side chamber 45r via the ports 45a and 45b, the piston 47 advances because the pressure-receiving area of ​​the piston 47 in the head side chamber 45h is larger than the pressure-receiving area of ​​the piston 47 in the rod side chamber 45r. At this time, the check valve 51 is closed by the force of a spring (not shown), which will be described later. And / or, as the piston 47 advances, the pressure in the rod side chamber 45r becomes higher than the pressure in the head side chamber 45h, and the check valve 51 is closed. This operation may be used, for example, in the operation of FIG. 6, which will be described later.

[0066] When hydraulic fluid is supplied to the rod side chamber 45r via the port 45b and hydraulic fluid is allowed to be discharged from the head side chamber 45h to the tank 59 (FIG. 5) via the port 45a, the pressure in the rod side chamber 45r becomes higher than the pressure in the head side chamber 45h, and the check valve 51 is closed. The piston 47 is moved backward by the pressure in the rod side chamber 45r. Note that the hydraulic fluid may be discharged from the head side chamber 45h to a destination other than the tank 59. This operation may be used, for example, for the operation in FIG. 7 described later.

[0067] When hydraulic fluid is supplied to the head side chamber 45h through the port 45a and the hydraulic fluid is allowed to be discharged from the rod side chamber 45r through the port 45b to the tank 59, the piston 47 advances due to the pressure in the head side chamber 45h. Even if hydraulic fluid flows from the head side chamber 45h to the rod side chamber 45r through the check valve 51, the piston 47 still advances because the pressure-receiving area of ​​the piston 47 in the head side chamber 45h is larger than the pressure-receiving area of ​​the piston 47 in the rod side chamber 45r. When the piston 47 advances, if the pressure in the rod side chamber 45r becomes larger than the pressure in the head side chamber 45h, the check valve 51 is closed. In this case, the piston 47 continues to advance. When the piston 47 reaches the forward limit, the hydraulic fluid supplied to the head side chamber 45h is discharged to the tank 59 through the check valve 51 and the rod side chamber 45r. This operation may be used, for example, for the operation of FIG. 8 described later.

[0068] (3.2. Cylinder Structure) The die-casting machine DC (or the die-casting machine 1 or the absorbing device 2) may have one or more cylinders 43. However, in the description of the embodiment, a description may be given focusing on one cylinder 43 unless otherwise specified.

[0069] The number of advancing and retracting members 41 driven by one cylinder 43 may be one (as shown in the illustrated example) or two or more. In the latter case, for example, as can be inferred from a known extrusion device, a plate-like member facing the advancing and retracting direction of the advancing and retracting member 41 may be connected to the cylinder 43, and a plurality of advancing and retracting members 41 may be fixed in parallel to this plate-like member. For convenience, the description of this embodiment will be given by taking the illustrated embodiment (an embodiment in which one cylinder 43 drives one advancing and retracting member 41) as an example.

[0070] The general configuration of the cylinder 43 has already been described. The cylinder member 45 is, for example, a generally cylindrical member. The internal cross-sectional shape of the cylinder member 45 is, for example, circular. The external shape (outer shape) of the cylinder member 45 may be an appropriate shape such as a rectangular parallelepiped. The piston 47 is, for example, a generally cylindrical member, and is capable of sliding in the axial direction inside the cylinder member 45. The rod 49 is, for example, a generally cylindrical member. The diameter of the rod 49 is smaller than the diameter of the piston 47.

[0071] In the description of the embodiments, for convenience, unless otherwise specified, the cross-sectional shapes of the piston 47 and the rod 49 are assumed to be circular. Therefore, for example, the description of the diameter of the cross section and the description of the area of ​​the cross section may be mutually applicable based on the relationship between the diameter and area of ​​a circle.

[0072] The dimensions of the piston 47, the rod 49, etc. are arbitrary. In this embodiment, as will be understood from the operation described later, when the piston 47 is retracted by supplying hydraulic fluid from a hydraulic pressure source (e.g., a pump or an accumulator) to the rod side chamber 45r, a large driving force is not required. Alternatively, unlike the description of the embodiment, the operation of generating a driving force by supplying hydraulic fluid from a hydraulic pressure source to the rod side chamber 45r does not have to be performed. Therefore, the ratio of the diameter of the rod 49 to the diameter of the piston 47 (<1) may be made larger than that of a normal hydraulic cylinder. From another perspective, the diameters of the piston 47 and the cylinder member 45 may be made smaller to achieve miniaturization.

[0073] For example, the value obtained by dividing the pressure receiving area in the rod side chamber 45r of the piston 47 by the pressure receiving area in the head side chamber 45h of the piston 47 is generally about 4 / 5. In contrast to this, in the cylinder 43, the above value may be, for example, 3 / 5 or less, or may be, for example, about 1 / 2 (for example, 4 / 10 or more and 6 / 10 or less, or 9 / 20 or more and 11 / 20 or less). When the above value is 1 / 2, the driving force when a predetermined pressure (the same pressure) is applied to both the rod side chamber 45r and the head side chamber 45h and the driving force when the above predetermined pressure is applied only to the rod side chamber 45r (the head side chamber 45h is set to tank pressure) are approximately equal to each other.

[0074] The cylinder 43 may have a packing (reference number omitted) at an appropriate position, such as between the piston 47 and the cylinder member 45. For convenience, even if a packing is interposed between the piston 47 and the cylinder member 45, it will be expressed as the piston 47 sliding relative to the cylinder member 45. Other components (e.g., the accumulator 65) may also have packing at appropriate positions. However, for convenience, illustrations or reference numbers may be omitted, and no particular mention will be made. Even if a packing is interposed, it will be expressed as sliding, as with the cylinder 43.

[0075] The piston 47 has physical forward and backward limits (driving limits) defined by abutment against the front and rear ends (this concept includes a stopper, not shown, provided inside the cylinder member 45) inside the cylinder member 45. As described above, the forward and / or backward limits may or may not define the forward and / or backward limits of the advancing and retracting member 41.

[0076] The piston 47 and the rod 49 (which may be regarded as a single member as a whole) have a flow passage 61 including a check valve 51. The shape of the flow passage 61 is arbitrary as long as it is possible to communicate the head side chamber 45h and the rod side chamber 45r. In the example of FIG. 3, the flow passage 61 has a first portion penetrating the piston 47 in the axial direction at its axis, and a second portion extending radially from the first portion through the rod 49. The number of second portions is arbitrary, and for example, one second portion may be provided, or multiple second portions may be provided radially. In FIG. 5 described later, two or more second portions are provided, and a cross section along two second portions extending in opposite directions from each other is shown.

[0077] 1(a), the cylinder 43 is arranged coaxially with the advancing / retreating member 41 on the opposite side to the cavity 107 of the advancing / retreating member 41, and the rod 49 side faces the advancing / retreating member 41. The cylinder member 45 is immobile with respect to the fixed mold 103 (the mold in which the advancing / retreating member 41 is arranged). The tip of the rod 49 is fixed to the rear end of the advancing / retreating member 41.

[0078] The advancing / retreating member 41 and the rod 49 may be fixed by an appropriate method. For example, the advancing / retreating member 41 and the rod 49 may be fixed by a coupling (FIG. 1(a)), or a female screw provided on one of the tip of the rod 49 and the rear end of the advancing / retreating member 41 may be screwed into a male screw provided on the other. In theory, the advancing / retreating member 41 and the rod 49 may be integrally formed and fixed to each other. The fixed mold 103 (the mold in which the advancing / retreating member 41 is arranged) and the cylinder member 45 may also be fixed by an appropriate method. For example, the cylinder member 45 may be fixed to the fixed mold 103 and / or the fixed die plate 13 by a bolt or the like. At least a part of the cylinder member 45 may be integrally formed with the fixed mold 103 and fixed to the fixed mold 103.

[0079] (3.3. Check valve configuration) As described above, the position of the check valve 51 is arbitrary and is not limited to the piston 47. For example, the check valve 51 may be provided in the cylinder member 45, in a block fixed to the outer surface of the cylinder member 45, or away from the cylinder member 45. In the case where a flow path 61 including the check valve 51 and a run-around circuit 53 separate from the flow path 61 are provided, the length of the flow path 61 (e.g., the length along the center line) may be shorter than the length of the run-around circuit 53, for example. Note that in the description of the embodiments, the description may be made on the assumption that the check valve 51 is provided in the piston 47, unless otherwise specified.

[0080] The check valve 51 may have various configurations and may have a known configuration, except that it is provided on the piston 47. For example, although not particularly shown, the check valve 51 has a valve body including a valve flow path through which the working fluid flows from the head side chamber 45h side to the rod side chamber 45r side, and a valve body that is movable relative to the valve body. The valve body can block the valve flow path, for example, by abutting against a valve seat of the valve body in the valve flow path from the rod side chamber 45r side to the head side chamber 45h side.

[0081] The check valve 51 has, for example, a spring that presses the valve disc against the valve seat. Therefore, when the force of the working fluid from the head side chamber 45h side pressing the valve disc exceeds the force of the spring pressing the valve disc, the valve disc separates from the valve seat. This allows flow from the head side chamber 45h to the rod side chamber 45r. Conversely, if this is not the case, flow from the rod side chamber 45r to the head side chamber 45h is prohibited. The spring may be omitted.

[0082] The valve body may be formed, for example, by appropriately combining a plurality of members having appropriate shapes. A member occupying most of the piston 47 may form at least a part of the valve body. For example, the valve flow passage may be such that the portion on the head side chamber 45h side with respect to the valve seat and the valve body and the portion on the opposite side are positioned on the same straight line, or may intersect with each other. The valve body may be, for example, a poppet combining a conical portion and a cylindrical portion, or may be spherical as shown by the symbol in FIG. 3. The shape of the valve seat is also arbitrary.

[0083] The check valve 51 is not a pilot type. In other words, the check valve 51 always allows flow from the head side chamber 45h to the rod side chamber 45r and prohibits flow in the opposite direction (hereinafter, sometimes referred to as "allowing one-way flow"). However, the check valve 51 may be a pilot type.

[0084] As described above, the check valve 51 allows one-way flow during the process in which the piston 47 moves from the rod side chamber 45r side to the head side chamber 45h side. From another perspective, the flow path 61 does not have a mechanism (for example, a control valve combining the check valve 51 with another check valve; see Patent Document 6) that enables the check valve 51 to allow one-way flow only when the piston 47 is at the forward limit (drive limit on the rod side chamber 45r side) and / or the backward limit (drive limit on the head side chamber 45h side). In other words, the check valve 51 allows one-way flow when the piston 47 is at any position in the range from the forward limit to the backward limit (always or at a predetermined time). However, the check valve 51 may allow one-way flow only in a predetermined range including the forward limit.

[0085] Strictly speaking, even in the case where a mechanism is provided in which the one-way flow is permitted by the check valve 51 only when the piston 47 is at the driving limit, the one-way flow is permitted not only when the piston 47 is at the driving limit but also when the piston 47 is within a small length from the driving limit. The small length is, for example, equal to or less than the movable distance of the valve disc of a check valve other than the check valve 51 for enabling and disabling the one-way flow permit. When it is said that the one-way flow is permitted during the movement of the piston 47, the mode of the operation does not include a mode in which the one-way flow is permitted only within such a small length. The movable distance of the valve disc of the check valve 51 may be referred to as the above-mentioned small length.

[0086] Also, for example, no component is provided to restrict the flow from the head side chamber 45h to the check valve 51. For example, no orifice or relief valve (see FIG. 3 of Patent Document 5) is provided between the head side chamber 45h and the check valve 51. The same applies to the check valve 51 and the rod side chamber 45r. From another perspective, the flow path 61 connecting the head side chamber 45h and the rod side chamber 45r has only the check valve 51 as a valve. Also, for example, in the flow path 61, the minimum area of ​​the cross section on the head side chamber 45h side and / or the rod side chamber 45r side of the check valve 51 (the total of the minimum areas when the flow path is branched into a plurality of flow paths) is larger than the minimum area of ​​the cross section in the check valve 51 (for example, the area of ​​the gap between the valve seat and the valve body, or the opening area of ​​the port of the poppet having the flow path). This is an example of an embodiment in which no orifice is provided.

[0087] However, for example, within the scope of not impeding the operation intended in the present disclosure, the flow path 61 may have a portion where the cross-sectional area is reduced, or may have a valve other than the check valve 51. For example, a relief valve may be provided that prohibits flow from the head side chamber 45h to the check valve 51 when the pressure of the molten metal is lower than the expected surge pressure by a certain degree, and further when the pressure in the head side chamber 45h is lower than a predetermined threshold, and allows flow from the head side chamber 45h to the check valve 51 otherwise.

[0088] (4. Hydraulic system of the absorber) 5 to 8 are diagrams showing the configuration of the absorbing device 2. As described in the explanation of the operation of the absorbing device 2 below, FIG. 5 to FIG. 8 show different states from each other. In these figures, the flow paths in a state where a relatively high pressure is applied are shown with thicker lines than the other flow paths. Also, the advancing and retracting member 41 and the rod 49 are shown as a single, integrated member. This may be understood as merely being shown as a single member for the sake of convenience, or may be understood as actually being a single member.

[0089] Of the hydraulic system included in the absorbing device 2, a portion excluding the cylinder 43 (including the check valve 51 in this embodiment) is referred to as the hydraulic device 63. The cylinder 43 and the hydraulic device 63 may be implemented (for example, manufactured and / or distributed) separately. In this case, unlike the description of the embodiment, only the cylinder 43 may be regarded as the surge pressure absorbing device, or only the hydraulic device 63 may be regarded as the surge pressure absorbing device. Also, a combination of the mold 101, the advancing and retracting member 41, and the cylinder 43 may be distributed as a surge pressure absorbing mold separately from the hydraulic device 63. Unlike the present embodiment, in a mode in which the check valve 51 is not built in the cylinder 43, the check valve 51 may be manufactured and / or distributed separately from the cylinder 43, and in this case, the check valve 51 may be regarded as a component of the hydraulic device 63.

[0090] The hydraulic device 63 generally has the following three parts: A configuration related to the flow of hydraulic fluid from the head side chamber 45h to the accumulator 65 as the advancing / retracting member 41 retracts; A configuration related to the supply of hydraulic fluid from a hydraulic pressure source (pump 57 in the illustrated example) to the cylinder 43 and the discharge of hydraulic fluid from the cylinder 43 to the tank 59; and other configurations. Each of these configurations will be described below in order.

[0091] (4.1. Configuration from cylinder to accumulator) The accumulator 65 is connected to the head side chamber 45h via an ACC flow path 67A. The ACC flow path 67A has an ACC valve 69 that controls the flow of the ACC flow path 67A. The ACC valve 69 contributes to reducing the likelihood that the hydraulic fluid will flow into the accumulator 65 when, for example, the hydraulic fluid is supplied from the pump 57 to the head side chamber 45h to move the piston 47 forward. In the illustrated example, the ACC valve 69 is a pilot type valve. The introduction of the pilot pressure is controlled by a pilot valve 71. The specific configuration of each component is, for example, as follows:

[0092] The accumulator 65 may be of various types, for example, a weight type, a spring type, a gas pressure type, a piston type, or a bladder type. In the weight type, pressure is applied to the hydraulic fluid by the gravity of a weight. In the spring type, pressure is applied to the hydraulic fluid by the restoring force of a spring. In the gas pressure type, compressed gas directly contacts the hydraulic fluid to apply pressure to the hydraulic fluid. In the piston type, compressed gas applies pressure to the hydraulic fluid through a piston. In the bladder type, compressed gas applies pressure to the hydraulic fluid through a flexible bladder (diaphragm). In the gas pressure type, piston type, and bladder type, the gas is, for example, air or an inert gas (e.g., nitrogen).

[0093] In Fig. 5, a piston-type accumulator is illustrated as the accumulator 65. Although no particular reference numeral is given, the accumulator 65 has a cylinder member and a piston housed in the cylinder member. The inside of the cylinder member is partitioned into a liquid chamber that houses a liquid and a gas chamber that houses a gas. The accumulator 65 applies pressure to the working fluid in the liquid chamber by the pressure of compressed gas (e.g., nitrogen or air) in the gas chamber. The liquid chamber is connected to the ACC flow path 67A.

[0094] The ACC valve 69 may have various configurations as long as it is possible to prohibit the flow from the head side chamber 45h side to the accumulator 65 side. In the illustrated example, the ACC valve 69 is configured by a logic valve controlled by the pressure (pilot pressure) introduced from the flow path 67B.

[0095] Specifically, in the illustrated ACC valve 69, a spring (reference numeral omitted) applies a restoring force to the valve body (reference numeral omitted) toward the closed position (position for closing the ACC valve 69). Both the pressure in the ACC flow passage 67A (from another point of view, the head side chamber 45h) and the pressure in the accumulator 65 act as forces directing the valve body toward the open position. Therefore, when pilot pressure is not introduced, the ACC valve 69 is opened when the sum of the forces applied to the valve body by the pressure in the ACC flow passage 67A and the pressure in the accumulator 65 toward the open position (when the force by one pressure is 0, the force by the other pressure) exceeds the restoring force. Also, when pilot pressure is introduced, the sum of the force applied to the valve body by the pilot pressure toward the closed position and the restoring force exceeds the force applied to the valve body toward the open position, so that the ACC valve 69 is closed. Examples of configurations of the ACC valve 69 other than the illustrated example include a check valve, a switching valve, a flow control valve, a pressure control valve, and a solenoid valve.

[0096] The pilot valve 71 introduces and stops the introduction of pilot pressure to the ACC valve 69. Various configurations are possible, and FIG. 5 illustrates a 4-port, 2-position changeover valve. However, one of the four ports is blocked and unused. In the rectangular state (position) on the right side of the figure, the pilot valve 71 connects the flow path 67B connected to the pilot port of the ACC valve 69 to the tank 59. This stops the introduction of pilot pressure to the ACC valve 69. In addition, in the rectangular state (position) on the left side of the figure, the pilot valve 71 connects the flow path 67B to the pump 57. This introduces pilot pressure to the ACC valve 69. The driving method of the pilot valve 71 is arbitrary, and FIG. 4 illustrates a method in which a spring that moves the pilot valve 71 to the rectangular position on the right side of the figure and a solenoid that moves the pilot valve 71 to the rectangular position on the left side of the figure are combined.

[0097] The ACC flow path 67A branches off on the cylinder 43 side relative to the ACC valve 69 in response to the provision of multiple cylinders 43. When multiple cylinders 43 are provided, unlike the illustrated example, one accumulator 65 may be provided corresponding to each cylinder 43. Also, as in the illustrated example, a configuration in which multiple cylinders 43 are connected to one accumulator 65 may be provided in multiple configurations.

[0098] The ACC flow path 67A, for example, has only the ACC valve 69 as a valve controlled by the control device 5 between the head side chamber 45h and the accumulator 65, and has no other valves. The ACC flow path 67A may or may not have a valve that is not controlled by the control device 5 (for example, a manual valve). Also, for example, in the ACC flow path 67A, the minimum cross-sectional area of ​​the portion other than the ACC valve 69 (the sum of the minimum areas if branched) is larger than the minimum cross-sectional area inside the ACC valve 69. With this configuration, the pressure loss of the ACC flow path 67A is reduced.

[0099] The various flow paths (including flow paths other than the ACC flow path 67A) of the hydraulic device 63 may be configured appropriately. For example, each flow path may be configured by a rigid tube, a flexible hose, a block in which a flow path is formed, and / or a combination of these.

[0100] (4.2. Configuration from pump and tank to cylinder) The hydraulic device 63 has the already mentioned pump 57, tank 59, and switching valve 55. The hydraulic device 63 also has a check valve 73 that prevents backflow to the pump 57. The specific configuration of each element is, for example, as follows.

[0101] The pump 57 and / or the tank 59 may or may not be shared with a hydraulic device (e.g., a hydraulic device of the injection device 9) other than the absorbing device 2 of the die casting machine 1. The pump 57 and the tank 59 may be shared by a plurality of die casting machines 1. The pump 57 and the tank 59 may be of such a form that it is difficult to regard them as components of the die casting machine 1 (hydraulic device 63).

[0102] The pump 57 and the tank 59 may have various configurations, for example, known configurations. The pump 57 may be driven as needed, or may be driven constantly. The pump 57 is capable of arbitrarily adjusting the pressure it supplies, for example. The adjustment may be realized, for example, by controlling the rotation speed of a motor 75 that drives the pump 57. The motor 75 may be, for example, an AC servo motor or may be inverter controlled. The tank 59 is, for example, of an open-to-atmosphere type. In other words, the tank pressure is approximately atmospheric pressure. Therefore, the pressure of the flow paths connected to the tank 59 is theoretically approximately atmospheric pressure.

[0103] The switching valve 55 is configured as a 4-port 3-position switching valve. In the rectangular state (position) on the left side of the figure, the switching valve 55 connects the pump 57 to the head side chamber 45h and also connects the tank 59 to the rod side chamber 45r. This allows, for example, the piston 47 to move forward. In addition, in the rectangular state (position) on the right side of the figure, the switching valve 55 connects the pump 57 to the rod side chamber 45r and also connects the tank 59 to the head side chamber 45h. This allows, for example, the piston 47 to move backward. In addition, in the rectangular state (position) in the center of the figure, the switching valve 55 connects the rod side chamber 45r, the head side chamber 45h, and the pump 57 to each other, as already described with reference to FIG. 3.

[0104] The switching valve 55 may be driven by any method, and Fig. 5 illustrates a method in which a spring that moves the switching valve 55 to the rectangular position in the center of the figure is combined with a solenoid that moves the switching valve 55 to the rectangular positions on the right and left sides of the figure. The rectangular position in the center of the figure is the neutral position when the solenoid is not driven.

[0105] A flow path (reference numeral omitted) for connecting the head side chamber 45h and the switching valve 55 and an ACC flow path 67A for connecting the head side chamber 45h and the accumulator 65 share a part on the head side chamber 45h side. From another point of view, both flow paths are connected to each other. Therefore, for example, when the switching valve 55 is in the rectangular state on the left side of the figure, the pump 57 contributes to applying pressure to the ACC flow path 67A, and can therefore contribute to opening the ACC valve 69 and accumulating pressure in the accumulator 65.

[0106] The check valve 73 permits a flow from the pump 57 and prohibits a flow in the opposite direction. A flow path (reference number omitted) connecting the pump 57 and the switching valve 55 and a flow path (reference number omitted) connecting the pump 57 and the pilot valve 71 are shared with each other in a portion on the side of the pump 57. The check valve 73 is located in that shared portion.

[0107] (4.3. Other configurations of the hydraulic device) The hydraulic device 63 has a drain passage (reference number omitted) that connects the ACC passage 67A and the tank 59, and a drain valve 79 located in the passage. The drain passage contributes to discharging the working fluid from the ACC passage 67A and components (e.g., the head side chamber 45h and / or the accumulator 65) connected to the ACC passage 67A, for example, during maintenance of the absorbing device 2. During the molding cycle, the drain valve 79 is kept in a state in which it blocks the ACC passage 67A and the tank 59 (a rectangular state on the left side of the drawing).

[0108] The hydraulic device 63 has a pressure sensor 77 that detects the pressure in the head side chamber 45h. This pressure sensor 77 is referenced, for example, when adjusting the pressure in the head side chamber 45h when absorbing surge pressure or when adjusting the pressure in the head side chamber 45h when applying local pressure. In other words, the pressure sensor 77 is used for feedback control of pressure. The pressure sensor 77 may detect the pressure at any position as long as it can detect the pressure in the head side chamber 45h. In the illustrated example, the pressure sensor 77 detects the pressure in a portion of the ACC flow path 67A that is closer to the head side chamber 45h than the ACC valve 69. The configuration of the pressure sensor 77 is also arbitrary.

[0109] The hydraulic device 63 has a temperature sensor 81 that detects the temperature of the mold 101. The temperature sensor 81 contributes to setting a target pressure of the head side chamber 45h (and / or the accumulator 65) when absorbing surge pressure, for example. Specifically, when the temperature of the mold 101 changes, the flow of the molten metal 109 also changes, and the magnitude of the surge pressure also changes. In general, when the temperature of the mold 101 increases, the surge pressure increases. Therefore, for example, the target pressure (from another point of view, the degree of absorption of the surge pressure by the hydraulic device 63) is increased according to the increase in the temperature detected by the temperature sensor 81. The configuration and position of the temperature sensor 81 are arbitrary. For example, a temperature sensor that detects the temperature of the mold 101 for another purpose is known, and the configuration and position of the temperature sensor 81 may be the same as those of such a temperature sensor.

[0110] The relative relationship between the detected temperature (and / or the amount of change therein) and the target pressure (and / or the amount of change therein) may be appropriately set based on experiments, etc. The control device 5 stores, for example, a map in which temperatures and target pressures correspond to each other, and sets the target pressure according to the detection value of the temperature sensor 81 by referring to the map. The map may be created by the manufacturer of the hydraulic device 63 and the user of the hydraulic device 63, or may be created by the control device 5 or a server that communicates with the control device 5 based on the temperature and surge pressure detected in a trial run and / or a past molding cycle.

[0111] Although not particularly shown, the absorbing device 2 may have a position sensor that directly detects the position of the advancing / retreating member 41 or the rod 49. The absorbing device 2 may also have a flow rate sensor that detects the flow rate of the working fluid discharged from the rod side chamber 45r. Such a position sensor or flow rate sensor contributes, for example, to detection of the position and / or movement of the advancing / retreating member 41. The absorbing device 2 may have a pressure sensor that detects the pressure in the rod side chamber 45r. This pressure sensor contributes, for example, to calculation of the pressure applied to the molten metal by the advancing / retreating member 41 together with the pressure sensor 77 that detects the pressure in the head side chamber 45h.

[0112] (5. Operation of the injection unit) Fig. 9 is a diagram for explaining the operation related to injection. In this figure, the horizontal axis indicates time t, with the right side indicating later time points. The left vertical axis indicates velocity V, with the upper side indicating higher velocity. The right vertical axis indicates pressure P, with the upper side indicating higher pressure.

[0113] Line LnV shows the change over time in the injection speed (speed of plunger 21). Line LnP shows the change over time in the injection pressure. Here, the injection pressure is the pressure applied to the molten metal by plunger 21. Note that the speed or pressure shown by lines LnV and LnP may be considered to indicate target values ​​or actual values. Also, the waveforms shown by these lines are merely examples.

[0114] The die casting machine 1 performs, for example, low speed injection (times t0 to t1), high speed injection (times t1 to t2), and pressure boosting and pressure holding (from around time t2) in that order. That is, as shown by the line LnV, the die casting machine 1 performs injection at a relatively low speed (speed V L Next, the die casting machine 1 performs low-speed injection by moving the plunger 21 forward at a relatively high speed (speed V H) to advance the plunger 21. Next, as shown by line LnP, the die casting machine 1 increases the pressure applied to the molten metal by the plunger 21 in order to eliminate shrinkage cavities. After that, as shown by line LnP, the die casting machine 1 performs pressure dwell to maintain the casting pressure Pc (final pressure) obtained by the pressure increase.

[0115] Supplementing the above operation, the injection pressure is relatively low during low-speed injection (times t0 to t1). For convenience, the injection pressure during low-speed injection is omitted in FIG. 9 because it is extremely small. Thereafter, when high-speed injection is started (time t1), the injection pressure rises. Furthermore, when the filling of the molten metal is almost completed (around time t2), the molten metal has nowhere to go, so the injection speed drops sharply and the injection pressure rises sharply. Deceleration injection to reduce the injection speed may be performed. However, in this embodiment, the surge pressure is absorbed by the absorption device 2, so there is little need for deceleration injection. The injection pressure may simply rise because the molten metal has nowhere to go. That is, no special operation for increasing the pressure may be performed. During pressure holding, the injection speed is approximately zero.

[0116] The pressure boosting may be performed in various ways. For example, the pressure boosting may be performed by supplying the hydraulic fluid to the head side chamber 23h (FIG. 1(a)) of the injection cylinder as the driving unit 23 following the injection in which the speed is controlled, and by performing pressure control. The pressure boosting may also be performed by supplying the hydraulic fluid to the head side chamber 23h from an accumulator different from the accumulator that supplied the hydraulic fluid to the head side chamber 23h during the injection. The pressure boosting may also be performed by supplying the hydraulic fluid to a boosting cylinder that increases the pressure of the head side chamber 23h in a boosting type injection cylinder different from the injection cylinder illustrated in FIG. 1(a). FIG. 9 illustrates an example in which a boosting type injection cylinder is used, and the casting pressure Pc is higher than the pressure P1 (near time t3) obtained by applying hydraulic pressure to the head side chamber 23h.

[0117] Line Ln1 indicates the minimum pressure at which burrs are generated (burr limit curve). This pressure is roughly proportional to √t. Line Ln0 indicates a portion of the injection pressure that may be generated when the absorbing device 2 is not provided. As shown in this figure, when the absorbing device 2 is not provided, a surge pressure is generated at the completion of filling, and the injection pressure may exceed the burr limit curve, causing burrs to be generated. In the embodiment, since such a surge pressure is reduced, for example, it is easy to make the pressure near the completion of filling (near time t3) lower than the burr limit curve, or to make the pressure thereafter closer to the burr limit curve.

[0118] (6. Operation of the Absorber) The die-casting machine 1 repeats, for example, a molding cycle. Figures 5 to 8 show a series of operations performed by the absorbing device 2 in each molding cycle. The operation (state) of the absorbing device 2 transitions in the order of Figures 5, 6, 7, and 8. Specifically, it is as follows.

[0119] (6.1. State before surge pressure absorption) Fig. 5 shows a state when the molten metal reaches the advancing / retracting member 41. Except for the fact that the molten metal 109 has reached the advancing / retracting member 41 in Fig. 5, Fig. 5 may be understood to show a state before (for example, immediately before) the molten metal reaches the advancing / retracting member 41.

[0120] Before the molten metal 109 reaches the advancing / retracting member 41, the control device 5 controls the hydraulic device 63 (from another point of view, the ACC valve 69) to allow flow between the ACC flow path 67A (from another point of view, the head side chamber 45h of the cylinder 43) and the accumulator 65. Specifically, the control device 5 sets the pilot valve 71 to the rectangular state on the right side of the figure, and stops the introduction of pilot pressure to the ACC valve 69. In addition, the control device 5 activates the runaround circuit 53 shown in FIG. 3. Specifically, the control device 5 sets the switching valve 55 to the rectangular position in the center of the figure.

[0121] The pressure in the head side chamber 45h is adjusted to a predetermined target pressure. This adjustment is realized, for example, by the control device 5 performing feedback control of the pump 57 (motor 75) based on the detection value of the pressure sensor 77. The target pressure at this time may be set according to the detection value of the temperature sensor 81, as described above. In this case, the target pressure may be set, for example, for each molding cycle, or may be set for each predetermined number of molding cycles. The temperature of the mold 101 changes during the molding cycle. The temperature used to set the target pressure may be the temperature at any time during the molding cycle, or may be the average value for a predetermined period. Of course, the target pressure may be constant regardless of the temperature of the mold 101.

[0122] As a result of the above control, in the cylinder 43, the same pressure is applied to the rod side chamber 45r and the head side chamber 45h. The piston 47 and the advancing / retracting member 41 are stopped at the forward limit. The pressure of the accumulator 65 may be approximately equal to the pressure of the head side chamber 45h, or may be higher than the pressure of the head side chamber 45h. In the former case, the piston of the accumulator 65 may be located near the drive limit on the liquid chamber side, or may be spaced a certain distance from the drive limit toward the gas chamber side. In the latter case, the piston of the accumulator 65 is located at the drive limit on the liquid chamber side.

[0123] The specific value of the target pressure is arbitrary as long as it is equal to or smaller than the magnitude at which the force of the molten metal 109 pushing the advancing / retreating member 41 can be made to retreat when a surge pressure of a predetermined magnitude is generated. For example, the target pressure may be less than 1 MPa or may be equal to or greater than 1 MPa. As an example, the target pressure may be adjusted in increments of 0.1 MPa within a range of 1 MPa or more and 5 MPa or less. The above-mentioned predetermined magnitude related to the surge pressure may be assumed by any of the manufacturer, the operator, and the control device 5 of the absorbing device 2. Similarly, the target pressure may be set by any of the manufacturer, the operator, and the control device 5 of the absorbing device 2.

[0124] (6.2. Operation related to surge pressure absorption) When the injection device 9 injects the molten metal 109 into the cavity 107 of the die 101, the molten metal 109 reaches the advancing / retreating member 41. When the force of the molten metal 109 pushing the advancing / retreating member 41 backward (to the right in FIG. 5) exceeds the force of the cylinder 43 pushing the advancing / retreating member 41 forward, the advancing / retreating member 41 retreats as shown in FIGS. 2(a) and 2(b). At this time, as described above, there occurs a flow from the head side chamber 45h to the rod side chamber 45r via the check valve 51, a flow in the runaround circuit 53, and a flow from the head side chamber 45h to the accumulator 65. In addition, the backflow of the hydraulic fluid discharged from the head side chamber 45h to the pump 57 side is restricted by the check valve 73.

[0125] The pressure in the accumulator 65 increases as the hydraulic fluid flows into the accumulator 65 from the head side chamber 45h. That is, the force with which the cylinder 43 pushes the advancing / retreating member 41 forward increases. When this increased force is balanced with the force with which the molten metal pushes the advancing / retreating member 41 backward, the advancing / retreating member 41 stops. Alternatively, the advancing / retreating member 41 or the piston 47 reaches the retreat limit, causing the advancing / retreating member 41 to stop. Note that, unlike the explanation here, the advancing / retreating member 41 may stop when the piston of the accumulator 65 reaches the upper limit (the drive limit on the gas chamber side). Also, as will be understood from the explanation of the operation related to local pressurization below, the advancing / retreating member 41 may start moving forward (local pressurization) before naturally stopping as described above.

[0126] (6.3. Operation related to local pressure application) 6 shows a state when local pressurization is being performed. The control device 5 controls the hydraulic device 63 so as to advance the advancing and retracting member 41 at an appropriate time after the advancing and retracting member 41 starts to retract, thereby performing local pressurization. Specifically, for example, the control device 5 controls the ACC valve 69 so as to prohibit flow from the ACC flow path 67A to the accumulator 65. That is, the control device 5 sets the pilot valve 71 to the state shown on the left side of the figure. The control device 5 also controls the pump 57 (motor 75) so as to apply to the cylinder 43 a pressure higher than the pressure immediately after absorbing the surge pressure.

[0127] When advancing / retreating member 41, feedback control may be performed based on pressure sensor 77. The target value of the pressure applied by advancing / retreating member 41 to molten metal 109 may be a constant value, or may be set so as to increase along a predetermined pressure curve (a curve drawn on a graph with time on the horizontal axis and pressure on the vertical axis). Also, unlike the description here, the position of advancing / retreating member 41 may be controlled based on a sensor (not shown) that detects the position of advancing / retreating member 41.

[0128] After the local pressure application starts, the advancing / retreating member 41 stops at a position where, for example, the force of the cylinder 43 pushing the advancing / retreating member 41 forward and the force of the molten metal pushing the advancing / retreating member 41 backward are balanced. As a result, the advancing / retreating member 41 applies to the molten metal a pressure determined by the pressure applied to the cylinder 43. However, unlike the explanation here, the advancing / retreating member 41 may reach the forward limit before the above-mentioned balance occurs.

[0129] The pressure that the advancing / retracting member 41 finally applies to the molten metal is arbitrary. For example, this pressure may be lower, equal to, or higher than the pressure (pressure Pc in FIG. 9) that the plunger 21 finally applies to the molten metal. Note that Pascal's principle does not strictly hold for the molten metal as the molten metal solidifies. Therefore, for example, even if the pressure of the local pressurization is higher than pressure Pc, the plunger 21 will not retract as long as the difference is not too large.

[0130] In addition, the target value of the pressure applied by the pump 57 to the cylinder 43 may also be set appropriately. As an example, the target value of the pressure may be set and changed in units of 0.1 MPa within a range of 16 MPa or less.

[0131] The timing at which the control device 5 starts the local pressurization may be, for example, the timing at which an appropriate condition is satisfied, or the timing at which a predetermined time has elapsed since the above-mentioned condition is satisfied. In other words, the timing at which the control device 5 starts the local pressurization may be determined based on an appropriate condition.

[0132] The above condition may be, for example, that the retreat of the advancing / retreating member 41 is detected by a position sensor (not shown). The detection of retreat here may be detection of whether or not the advancing / retreating member 41 has retreated, detection of the amount of retreat of the advancing / retreating member 41 reaching a predetermined amount, or detection of whether or not the advancing / retreating member 41 has retreated to a predetermined position. Note that when the amount of retreat is relatively small and when the predetermined position is relatively close to the forward limit, it may be considered that the presence or absence of retreat of the advancing / retreating member 41 has been detected.

[0133] The condition that triggers the start of local pressurization may be something other than the detection of the retreat of the advancing / retreating member 41. For example, the above condition may be that a predetermined time has elapsed since the start of injection by the injection device 9. Also, for example, the condition may be that the molten metal has reached a predetermined position detected by a method other than the detection of the retreat of the advancing / retreating member 41 (for example, an electrical current sensor, a temperature sensor, or a pressure sensor).

[0134] (6.4. Spray-related operations) When the molten metal solidifies, the control device 5 ends the local pressurization by the advancing / retracting member 41. The control device 5 may appropriately determine whether the molten metal has solidified. For example, the control device 5 may determine whether the molten metal has solidified based on whether a predetermined time has passed from an appropriate point in time (e.g., the point in time when injection starts or the point in time when local pressurization starts).

[0135] When the local pressurization is terminated, the control device 5 may temporarily retract the advancing / retreating member 41 instead of simply returning the state of the absorbing device 2 to the state before the surge pressure was absorbed (the state in FIG. 5). This retraction may be performed, for example, until the advancing / retreating member 41 and / or the piston 47 reach their retraction limit. The retraction of the advancing / retreating member 41 may contribute, for example, to cooling and / or air removal by discharging the working fluid from the head side chamber 45h, or to spraying the portion of the mold 101 where the advancing / retreating member 41 slides. The spraying may be, for example, air blowing (cleaning) and / or spraying of a mold release agent.

[0136] FIG. 7 shows a state in which the reciprocating member 41 is retracted as described above.

[0137] The control device 5 sets the switching valve 55 to the rectangular state on the right side of the figure, for example. As a result, the hydraulic pressure of the pump 57 is applied to the rod side chamber 45r, and the head side chamber 45h is set to the tank pressure. As a result, the piston 47 retreats, and the advancing / retreating member 41 retreats. The pressure that the pump 57 applies to the rod side chamber 45r when retracting the advancing / retreating member 41 may be an appropriate pressure. For example, the pressure may be lower, equal to, or higher than the pressure when the advancing / retreating member 41 is made to wait in the initial position (for example, the forward limit) before the start of injection as described above. As an example, the pressure of the pump 57 may be set in units of 0.1 MPa within a range of 16 MPa or less.

[0138] When the advancing / retreating member 41 is retracted, the ACC valve 69 may be opened or closed. In the illustrated example, the former is used. That is, the pilot valve 71 is in the state shown on the right side of the figure, and pilot pressure is not introduced to the ACC valve 69. Therefore, the accumulator 65 discharges the hydraulic fluid in the fluid chamber to the tank 59. At this time, the piston of the accumulator 65 may or may not reach the driving limit on the fluid chamber side (for example, the ACC valve 69 may be closed before reaching the limit). From another point of view, the pressure of the accumulator 65 may be lower than the pressure before absorbing the surge pressure, or may be equal to the pressure before absorbing the surge pressure (for example, the ACC valve 69 may be closed when the pressure before absorbing the surge pressure is obtained).

[0139] (6.5. Operations related to preparation for absorbing surge pressure) Fig. 8 shows a state in which preparations are being made to bring the state into that of Fig. 5. In this state, the control device 5 brings the switching valve 55 into the rectangular state on the left side of the figure. That is, the pump 57 and the head side chamber 45h are connected, and the rod side chamber 45r and the tank 59 are connected. Then, the working fluid is supplied from the pump 57 to the head side chamber 45h. This causes the piston 47 to move forward. At this time, the working fluid in the rod side chamber 45r is discharged into the tank 59. Thereafter, the piston 47 reaches its forward limit.

[0140] The state of the rectangular shape on the left side of the diagram of the switching valve 55 may end when the piston 47 reaches the forward limit, or may continue until a predetermined end condition is satisfied even after the forward limit is reached. In the latter case, the hydraulic fluid supplied to the head side chamber 45h is discharged to the tank 59 via the check valve 51 and the rod side chamber 45r. This allows the hydraulic fluid remaining in the rod side chamber 45r to be discharged, for example, when the piston 47 reaches the forward limit. In addition, for example, the cylinder 43 can be cooled by causing the hydraulic fluid to flow through the head side chamber 45h and the rod side chamber 45r. The above end condition may be, for example, a predetermined time that has elapsed since the state of FIG. 8 was reached or since the piston 47 reached the forward limit. The length of the predetermined time is arbitrary, but is, for example, about 2 seconds.

[0141] When the advancing / retracting member 41 is advanced (and / or is at the forward limit) as described above, the ACC valve 69 may be opened or closed. In the illustrated example, the latter is assumed. That is, the pilot valve 71 is in the state shown on the left side of the figure, and pilot pressure is introduced to the ACC valve 69.

[0142] The magnitude of the pressure applied by the pump 57 to the head side chamber 45h when the advancing / retracting member 41 is advanced (and / or when it is located at the forward limit) is arbitrary. For example, the pressure may be lower, equal to, or higher than the pressure applied by the pump 57 to the head side chamber 45h when waiting for the molding material in the mold to reach the advancing / retracting member 41 (FIG. 5). The specific value is also arbitrary. As an example, the pressure of the pump 57 may be set in the range of 5 MPa to 16 MPa in increments of 0.1 MPa.

[0143] When a predetermined condition is satisfied after the advancing / retracting member 41 reaches the forward limit, the control device 5 puts the absorbing device 2 into the state shown in Fig. 5. The timing of the state shown in Fig. 5 can be any timing as long as it is before the molten metal reaches the advancing / retracting member 41. For example, the timing may be before the plunger 21 starts to advance, or after the plunger 21 starts to advance.

[0144] (7. Summary of the First Embodiment) As described above, the surge pressure absorbing device 2 according to the embodiment has a check valve 51 connected to the hydraulic cylinder 43. The cylinder 43 has a rod 49, a piston 47, and a cylinder member 45. The rod 49 is fixed to the advancing / retreating member 41 that can advance into the die (metal mold 101) and retreat to the opposite side. The piston 47 is fixed to the rod 49. The cylinder member 45 accommodates the piston 47. The inside of the cylinder member 45 is partitioned by the piston 47 into a rod side chamber 45r in which the rod 49 is located and a head side chamber 45h on the opposite side. The check valve 51 allows a flow from the head side chamber 45h to the rod side chamber 45r during the process in which the advancing / retreating member 41 retreats due to the pressure of the molding material (molten metal 109) in the die 101 and the piston 47 moves from the rod side chamber 45r side to the head side chamber 45h side, and prohibits a flow in the opposite direction.

[0145] From another perspective, the molding machine of the embodiment (die-casting machine 1 or molded die-casting machine DC) has an absorption device 2 as described above, a clamping device 7 that holds the mold 101, and an injection device 9 that injects molding material (molten metal 109) into the mold 101.

[0146] Therefore, for example, as described in the description of the outline of the embodiment, when surge pressure is applied to the advancing / retreating member 41 and the piston 47 retreats, the pressure generated in the head side chamber 45h can supply the working fluid in the head side chamber 45h to the rod side chamber 45r. As a result, the delay time of the retreat of the advancing / retreating member 41 and the piston 47 in response to an instantaneous pressure rise can be shortened, and the surge pressure can be effectively absorbed. The absorption of the surge pressure can reduce the likelihood of flash formation. From another perspective, by controlling the magnitude of the surge pressure, a necessary and sufficient pressure can be applied to the molten metal 109, reducing the occurrence of porosity. In other words, the quality of the product is improved.

[0147] Also, for example, in the case where the check valve 51 is not provided and the rod side chamber 45r and the head side chamber 45h are simply connected to each other, when hydraulic fluid is supplied to the rod side chamber 45r, the hydraulic fluid flows from the rod side chamber 45r to the head side chamber 45h. On the other hand, the pressure-receiving area of ​​the piston 47 in the rod side chamber 45r is smaller than the pressure-receiving area in the head side chamber 45h. Therefore, the piston 47 cannot be moved backward (FIG. 7). However, in this embodiment, since the check valve 51 is provided, the piston 47 can be moved backward. As a result, for example, spraying becomes possible.

[0148] Furthermore, since the check valve 51 (from another point of view, the flow path 61) is provided, the operation described with reference to Fig. 8 becomes possible. That is, by supplying hydraulic fluid to the head side chamber 45h while connecting the rod side chamber 45r to the tank 59, hydraulic fluid can be caused to flow in both the head side chamber 45h and the rod side chamber 45r. This makes it possible to cool the cylinder 43 and bleed air from the cylinder 43. For this operation, there is no need for a complicated mechanism that allows flow in one direction only when the forward limit or the backward limit is reached.

[0149] The check valve 51 may be included in the piston 47. From another perspective, a flow passage 61 that includes the check valve 51 and communicates between the head side chamber 45h and the rod side chamber 45r may be provided in the piston 47 and the rod 49 (it may be possible to provide only the piston 47).

[0150] In this case, for example, it is easier to shorten the flow path 61 compared to other embodiments (for example, an embodiment in which the check valve 51 is included in a block fixed to the outer surface of the cylinder member 45). On the other hand, the hydraulic fluid usually has a certain degree of compressibility, and a time delay occurs depending on the length of the flow path 61 and the like from when the piston 47 starts to retract until the hydraulic fluid in the head side chamber 45h is supplied to the rod side chamber 45r. Therefore, by shortening the flow path 61, the effect of increasing the above-mentioned responsiveness is improved.

[0151] The absorbing device 2 may further include a run-around circuit 53. The run-around circuit 53 may communicate between the rod side chamber 45r and the head side chamber 45h separately from the flow path 61 including the check valve 51 during the process in which the advancing / retracting member 41 retreats due to the pressure of the molten metal 109 in the mold 101 and the piston 47 moves from the rod side chamber 45r side to the head side chamber 45h side.

[0152] In this case, the working fluid flows from the head side chamber 45h to the rod side chamber 45r via both the flow path 61 and the runaround circuit 53, which improves the effect of increasing the responsiveness to the surge pressure, for example.

[0153] The absorbing device 2 may further include a switching valve 55 that switches the connection relationship between the rod side chamber 45r, the head side chamber 45h, the hydraulic pressure source (pump 57), and the tank 59. The switching valve may be switchable between a first state, a second state, and a third state. In the first state (the central rectangle in the symbol indicating the switching valve 55 in FIG. 5), the rod side chamber 45r, the head side chamber 45h, and the pump 57 are connected to each other. In the second state (the rectangle on the right side), the rod side chamber 45r and the pump 57 are connected to each other, and the head side chamber 45h and the tank 59 are connected to each other. In the third state (the rectangle on the left side), the rod side chamber 45r and the tank 59 are connected to each other, and the head side chamber 45h and the pump 57 are connected to each other. The runaround circuit 53 is configured by switching the switching valve 55 to the first state.

[0154] Therefore, the run-around circuit 53 is configured by the configuration for driving the piston 47 by supplying the hydraulic fluid from the pump 57 to the cylinder 43, and the effect of increasing the responsiveness to the surge pressure described above is achieved. As a result, the configuration is simplified. In addition, since the rod side chamber 45r and the head side chamber 45h are not only communicated with each other but also connected to the pump 57, a certain degree of pressure can be applied to the rod side chamber 45r and the head side chamber 45h by the pump 57 while waiting for the molten metal 109 to reach the advancing / retracting member 41. As a result, the probability of negative pressure being generated in the rod side chamber 45r when the piston 47 retreats with the retreat of the advancing / retracting member 41 can be further reduced. As a result, the effect of increasing the responsiveness is further improved.

[0155] The absorbing device 2 may further include a control device 5. The control device 5 may set the switching valve 55 to the third state (the rectangle on the left side of the symbol indicating the switching valve 55 in FIG. 8 ) after the advancing / retreating member 41 retreats due to the pressure of the molding material (molten metal 109) in the die (metal mold 101) and before the molten metal 109 in the metal mold 101 reaches the advancing / retreating member 41 in the next molding cycle.

[0156] In this case, for example, as described with reference to Fig. 8, the advancing and retracting member 41 can be advanced to prepare for absorbing surge pressure in the next molding cycle. In addition, the check valve 51 is provided to allow hydraulic fluid to flow through the head side chamber 45h and the rod side chamber 45r, thereby cooling the cylinder 43. That is, the check valve 51 provides both preparation for absorbing surge pressure and cooling by circulating hydraulic fluid. Moreover, as described above, the switching valve 55 also contributes to forming the run-around circuit 53. As a result, the absorbing device 2 is multifunctional with a simple configuration.

[0157] The absorption device 2 may further include an accumulator 65, an ACC flow path 67A, and an ACC valve 69. The ACC flow path 67A may lead from the accumulator 65 to the head side chamber 45h. In other words, one end of the ACC flow path 67A may be located in the accumulator 65, and the other end may be located in the head side chamber 45h. The ACC valve 69 may be located in the ACC flow path 67A, and may be opened by the pressure of at least one of the accumulator 65 and the head side chamber 45h, and may be closed by the introduction of a pilot pressure.

[0158] In this case, it is easy to reduce the pressure loss between the head side chamber 45h and the accumulator 65. This effect is improved particularly when the ACC flow path 67A does not have another valve. Therefore, for example, pressure is easily transmitted between the head side chamber 45h and the accumulator 65, and surge pressure is easily absorbed by the accumulator 65.

[0159] The absorbing device 2 may further include a supply unit (e.g., a hydraulic device 63) that applies hydraulic pressure to the head side chamber 45h, and a control device 5 that controls the hydraulic device 63. The control device 5 may cause the hydraulic device 63 to apply a predetermined hydraulic pressure to the head side chamber 45h over a period from before (the specific time point is arbitrary as described above) until the molding material (molten metal 109) injected into the die (metal mold 101) reaches the advancing / retracting member 41 (see FIG. 5).

[0160] In this case, the degree of absorption of the surge pressure by the absorber 2 is determined according to a predetermined pressure. From another point of view, for example, in a mode in which the surge pressure is absorbed only by the restoring force of a spring that presses the piston 47 toward the rod side chamber 45r (this mode may also be included in the present disclosure), the degree of absorption of the surge pressure cannot be adjusted, but in this embodiment, the degree of absorption can be adjusted. That is, in the absorber 2, not only is it easy to absorb the surge pressure, but it is also easy to control the surge pressure. This not only makes it easy to reduce the probability of flash generation, but also makes it easy to distribute a necessary and sufficient pressure to the molten metal 109 when the filling of the molten metal 109 is completed, and thus makes it easy to reduce the probability of porosity generation.

[0161] The control device 5 may change the above-mentioned predetermined pressure (in other words, the target pressure of the head side chamber 45h (accumulator 65) before absorbing the surge pressure) in accordance with the temperature of the mold (die 101).

[0162] In this case, for example, as described above, the degree of absorption of the surge pressure can be changed in response to the change in the magnitude of the surge pressure caused by the change in temperature of the mold 101. That is, the accuracy of the control of the surge pressure is improved. As a result, the effect of reducing both the flash and the porosity is improved.

[0163] After the molding material (molten metal 109) injected into the mold (die 101) reaches the advancing / retreating member 41 and the advancing / retreating member 41 retreats, the control device 5 may cause the supply section (e.g., hydraulic device 63) to apply hydraulic pressure to the head side chamber 45h that is higher than the above-mentioned specified pressure (in other words, the pressure in the head side chamber 45h when absorbing surge pressure), thereby advancing the advancing / retreating member 41 and performing localized pressurization.

[0164] That is, the surge pressure absorbing device 2 may also be used as a local pressurizing device. This, for example, simplifies the configuration of the die-casting machine DC (or the die-casting machine 1 or the absorbing device 2). In addition, since local pressurization can be started when the advancing / retracting member 41 is retracted and the working fluid in the head side chamber 45h is compressed, local pressurization can be started quickly. As a result, for example, the quality of the product is improved.

[0165] From another viewpoint, the hydraulic device 63 of the surge pressure absorbing device 2 according to the embodiment is connected to a hydraulic cylinder 43. The cylinder 43 has a rod 49, a piston 47, and a cylinder member 45. The rod 49 is fixed to a forward / backward member 41 that can advance into a die (metal mold 101) and retreat to the opposite side. The piston 47 is fixed to the rod 49. The cylinder member 45 accommodates the piston 47. The inside of the cylinder member 45 is partitioned by the piston 47 into a rod side chamber 45r in which the rod 49 is located and a head side chamber 45h on the opposite side. The hydraulic device 63 has a run-around circuit 53. The run-around circuit 53 communicates the rod side chamber 45r and the head side chamber 45h in the process in which the forward / backward member 41 retreats due to the pressure of the molten metal 109 in the metal mold 101 and the piston 47 moves from the rod side chamber 45r side to the head side chamber 45h side.

[0166] In this case, for example, similar to the action of the flow path 61 including the check valve 51, when a surge pressure is applied to the advancing / retreating member 41 and the piston 47 retreats, the pressure generated in the head side chamber 45h can supply the working fluid in the head side chamber 45h to the rod side chamber 45r. Note that, if the run-around circuit (53) is not limited to being separate from the flow path 61 and is defined as communicating between the rod side chamber 45r and the head side chamber 45h during the process in which the piston 47 moves from the rod side chamber 45r side to the head side chamber 45h side, unlike the description of the embodiment, the flow path 61 may be regarded as an example of the run-around circuit.

[0167] From another viewpoint, the hydraulic cylinder (cylinder 43) according to the embodiment includes a cylinder member 45, a piston 47, a rod 49, and a check valve 51. The piston 47 is accommodated in the cylinder member 45, and divides the inside of the cylinder member 45 into a rod side chamber 45r and a head side chamber 45h. The rod 49 is fixed to the piston 47, and extends to the outside of the cylinder member 45 via the rod side chamber 45r. The check valve 51 is included in the piston 47, and allows a flow from the head side chamber 45h to the rod side chamber 45r while prohibiting a flow in the opposite direction during the process in which the piston 47 moves from the rod side chamber 45r side to the head side chamber 45h side. From another viewpoint, the piston 47 does not have a special mechanism that enables the check valve 51 to allow a flow in one direction only when the piston 47 is at the forward limit and / or the backward limit.

[0168] With such a cylinder 43, for example, it is possible to realize an embodiment in which the piston 47 includes the check valve 51 in the absorbing device 2 according to the embodiment described above.

[0169] In the above various aspects, the die casting machine 1 or the die casting machine with mold DC is an example of a molding machine. The molten metal 109 is an example of a molding material. The mold 101 is an example of a mold. The cylinder 43 is an example of a hydraulic cylinder. The hydraulic device 63 is an example of a supply unit.

[0170] The present invention is not limited to the above-mentioned exemplary embodiments, and may be embodied in various forms.

[0171] The molding machine is not limited to a die-casting machine. For example, the molding machine may be another metal molding machine, an injection molding machine for molding resin, or a molding machine for molding a material in which thermoplastic resin or the like is mixed with wood powder. The molding machine is not limited to a horizontal clamping and horizontal injection molding machine, and may be, for example, a vertical clamping and vertical injection molding machine, a vertical clamping and horizontal injection molding machine, or a horizontal clamping and vertical injection molding machine. The die-casting machine is not limited to a cold chamber machine, and may be, for example, a hot chamber machine.

[0172] The injection is not limited to low-speed injection and high-speed injection, and may be, for example, laminar flow filling at a low speed. The advancing and retreating member may also be used as an ejection pin for ejecting a molded product formed by solidifying the molding material from the mold. The surge pressure absorbing device does not have to be used for local pressure application.

[0173] It has already been mentioned that the run-around circuit 53 may not be provided. In this case, the rod side chamber 45r may be configured such that, for example, discharge of the hydraulic fluid from the port 45b is prohibited or permitted (for example, the port 45b may be connected to a tank 59). In addition, the run-around circuit 53 may not be connected to the pump 57.

[0174] In the embodiment, the state of the hydraulic device 63 when the advancing / retreating member 41 is advanced (FIG. 8) is different from the state of the hydraulic device 63 when the advancing / retreating member 41 is made to wait at the forward limit (FIG. 5). However, the two may be the same. For example, the piston 47 may be advanced in the state of FIG. 5 without using the state of FIG. 8. Conversely, in a mode in which a run-around circuit is not used, it may be possible to wait for the molten metal to reach the advancing / retreating member 41 in the state of FIG. 8 (without introducing pilot pressure into the ACC valve 69).

[0175] It is not necessary to provide the accumulator 65. For example, the head side chamber 45h may be connected to the tank 59 via a relief valve.

[0176] Note that the concept of an absorbing device that does not require the check valve (51) may be extracted from the present disclosure. For example, the concept of an absorbing device having a run-around circuit 53 that communicates between the head side chamber 45h and the rod side chamber 45r may be extracted, or the concept of an absorbing device that adjusts the degree of absorption of surge pressure (the pressure in the head side chamber 45h) depending on the temperature of the mold may be extracted. [Explanation of symbols]

[0177] DC... die casting machine with mold (molding machine), 1... die casting machine (molding machine), 2... surge pressure absorbing device, 5... control device, 7... mold clamping device, 9... injection device, 41... advance / retreat member, 43... cylinder, 45... cylinder member, 45h... head side chamber, 45r... rod side chamber, 47... piston, 49... rod, 51... check valve, 63... hydraulic device, 101... mold (die).

Claims

1. a hydraulic cylinder including a rod fixed to a reciprocating member capable of advancing into a mold and retracting to the opposite side, a piston fixed to the rod, and a cylinder member accommodating the piston, the interior of the cylinder member being partitioned by the piston into a rod side chamber in which the rod is located and a head side chamber on the opposite side; a flow passage communicating the rod side chamber and the head side chamber; a check valve located in the flow path, which allows hydraulic fluid to flow from the head side chamber to the rod side chamber and prohibits hydraulic fluid from flowing in the opposite direction during a process in which the piston moves from the rod side chamber to the head side chamber as the advancing / retracting member retreats due to the pressure of the molding material in the mold; A surge pressure absorbing device having a

2. The flow passage and the check valve are included in the piston.

2. The surge pressure absorbing device according to claim 1.

3. The piston further includes a run-around circuit that communicates the rod side chamber and the head side chamber separately from the flow path including the check valve during the process in which the advancing / retreating member retreats due to the pressure of the molding material in the mold and the piston moves from the rod side chamber to the head side chamber.

2. The surge pressure absorbing device according to claim 1.

4. a switching valve that switches a connection relationship between the rod side chamber, the head side chamber, the hydraulic pressure source, and a tank, The switching valve is a first state in which the rod side chamber, the head side chamber, and the hydraulic pressure source are connected to each other; a second state in which the rod side chamber and the hydraulic pressure source are connected to each other and the head side chamber and the tank are connected to each other; a third state in which the rod side chamber and the tank are connected to each other and the head side chamber and the hydraulic pressure source are connected to each other; The runaround circuit is formed by switching the switching valve to the first state.

4. The surge pressure absorbing device according to claim 3.

5. The present invention further includes a control device for changing the switching valve to the third state after the advancing / retreating member is retracted by the pressure of the molding material in the mold and before the molding material in the mold reaches the advancing / retreating member in the next molding cycle.

5. The surge pressure absorbing device according to claim 4.

6. An accumulator; an ACC flow passage extending from the accumulator to the head side chamber; an ACC valve located in the ACC flow passage, opened by a pressure in at least one of the accumulator and the head side chamber, and closed by introduction of a pilot pressure; 2. The surge pressure absorbing device of claim 1 further comprising:

7. a supply section that applies a hydraulic pressure to the head side chamber; A control device for controlling the supply unit; and The control device controls the supply unit to apply a predetermined hydraulic pressure to the head side chamber over a period from before the molding material injected into the mold reaches the advancing / retreating member until the molding material reaches the advancing / retreating member.

2. The surge pressure absorbing device according to claim 1.

8. The control device changes the predetermined pressure in response to the temperature of the mold.

8. The surge pressure absorbing device according to claim 7.

9. The control device controls the supply unit to apply a liquid pressure higher than the predetermined pressure to the head side chamber after the molding material injected into the mold reaches the advancing / retreating member and the advancing / retreating member retreats, thereby advancing the advancing / retreating member and performing localized pressurization.

8. The surge pressure absorbing device according to claim 7.

10. A hydraulic device comprising: a rod fixed to an advance / retract member capable of advancing into a mold and retracting to the opposite side; a piston fixed to the rod; and a cylinder member accommodating the piston, the interior of the cylinder member being connected to a hydraulic cylinder partitioned by the piston into a rod side chamber in which the rod is located and a head side chamber on the opposite side, a run-around circuit is provided which communicates the rod side chamber and the head side chamber during a process in which the advancing / retreating member retreats due to a pressure of the molding material in the mold and the piston moves from the rod side chamber side to the head side chamber side, The runaround circuit includes: a flow passage communicating the rod side chamber and the head side chamber; and a valve capable of opening and closing the flow path. Hydraulic device for surge pressure absorber.

11. The surge pressure absorbing device according to claim 1 ; A mold clamping device for holding the mold; an injection device that injects a molding material into the mold; The molding machine has

12. A cylinder member; a piston accommodated in the cylinder member and dividing the interior of the cylinder member into a rod side chamber and a head side chamber; a rod fixed to the piston and extending to the outside of the cylinder member via the rod side chamber; a flow passage included in the piston and communicating between the rod side chamber and the head side chamber; a check valve located in the flow path, which allows a flow of hydraulic fluid from the head side chamber to the rod side chamber while prohibiting a flow in the opposite direction, during a process in which the piston moves from the rod side chamber to the head side chamber; A hydraulic cylinder having a

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