Injection device, molding machine and control method of a molding machine

Abstract

The injection device of the embodiment includes an injection cylinder including a rod connectable to a plunger that slides in a sleeve, a piston fixed to the rod, a cylinder tube in which the piston is slidably accommodated, a rod-side chamber in which the rod is disposed, and a head-side chamber located on the opposite side of the rod-side chamber with the piston interposed therebetween; a hydraulic pump; a flow control valve that controls the flow rate of the hydraulic fluid discharged from the rod-side chamber; and a control unit that, when advancing the piston toward the rod, controls the discharge amount of the hydraulic fluid of the hydraulic pump in a state in which the flow control valve is opened, and changes the supply amount of the hydraulic fluid to the head-side chamber in a manner of continuously or stepwise increasing.

Description

Technical Field

[0001] This invention relates to an injection device for filling cavities in a metal mold with liquid material, a molding machine, and a method for controlling the molding machine. Background Technology

[0002] Die casting machines manufacture molded products (die castings) by filling molten metal into cavities within a metal mold that has been closed using a mold-closing device through an injection unit. The injection unit, for example, includes an injection cylinder as an actuator. The injection cylinder includes, for example, a rod connectable to a plunger that slides within a sleeve, an injection piston fixed to the rod, and a cylinder barrel that slidably houses the piston internally. The cylinder barrel internally has a rod-side chamber for arranging the rod and a head-side chamber located on the opposite side of the rod-side chamber, sandwiching the injection piston between them.

[0003] By supplying actuating oil to the head chamber, the injection piston moves towards the rod side. As the injection piston moves, the plunger advances in the sleeve towards the metal mold, and the molten metal is filled into the cavity within the metal mold.

[0004] For example, the speed of the injection piston can be controlled by using a flow control valve to control the flow rate of the actuating oil discharged from the rod-side chamber. This control method is called outlet throttling control.

[0005] When injecting molten metal using outlet throttling control, the oil in the rod-side chamber is compressed when the actuating oil is supplied to the head-side chamber, potentially causing the injection piston to fly out abruptly. If the injection piston flies out abruptly, air may be entrained into the molten metal. If air is entrained into the molten metal, the quality of the molded product may deteriorate.

[0006] Patent Document 1 describes an injection device that includes an auxiliary oil pressure supply unit for replenishing operating oil when the pressure of the operating oil in the rod-side chamber is below a reference value in order to suppress the rapid ejection of the injection piston.

[0007] For example, injection molding devices are also used when ejecting molded parts from a metal mold. By advancing the injection piston, the molded part is pushed out of the metal mold by the plunger. When ejecting the molded part from the metal mold, if the injection piston flies out abruptly, a pressure shock occurs. Due to the pressure shock, damage to the molded part or damage to the structure of the die-casting machine may occur.

[0008] Furthermore, injection devices are also used, for example, during the maintenance of die-casting machines. For instance, an injection device is used to move a plunger within a sleeve. If the injection piston flies out abruptly when moving the plunger, the accuracy of plunger position control decreases.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2019-72751 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] The problem to be solved by the present invention is to provide an injection device, a molding machine, and a control method for the molding machine that can suppress the rapid ejection of the piston.

[0014] Methods used to solve problems

[0015] An injection apparatus according to one embodiment of the present invention comprises: an injection cylinder including a rod that can be connected to a plunger that slides in a sleeve, a piston fixed to the rod, a cylinder slidably housing the piston, a rod-side chamber on which the rod is disposed, and a head-side chamber located on the opposite side of the rod-side chamber, sandwiching the piston therebetween; a hydraulic pump with a variable discharge amount of actuating fluid; a flow control valve for controlling the flow rate of the actuating fluid discharged from the rod-side chamber; and a control unit that, when the piston is advanced toward the rod side, controls the discharge amount of the actuating fluid from the hydraulic pump while the flow control valve is open, thereby varying the supply amount of the actuating fluid to the head-side chamber in a manner that increases continuously or in stages.

[0016] In the injection device of the above technical solution, it is preferable that the control unit changes the amount of the pumping fluid discharged by the hydraulic pump.

[0017] In the injection device of the above technical solution, it is preferable to further include a pressure sensor that measures the pressure of the action fluid in the head chamber; the control unit changes the amount of action fluid ejected by the hydraulic pump based on the pressure of the action fluid in the head chamber measured by the pressure sensor.

[0018] In the injection device of the above technical solution, it is preferable that when the pressure of the action fluid in the head chamber measured by the pressure sensor reaches a predetermined pressure, the control unit reduces the change in the amount of action fluid ejected by the hydraulic pump.

[0019] In the injection device of the above technical solution, it is preferable to further include a position sensor that measures the position of the rod or the piston; the control unit changes the amount of the pumped fluid of the hydraulic pump based on the position of the rod or the piston measured by the position sensor.

[0020] In the injection device of the above technical solution, it is preferable that the control unit changes the amount of the pumped fluid of the hydraulic pump based on the speed of the rod or piston calculated according to the position of the rod or piston measured by the position sensor.

[0021] In the injection device of the above-described technical solution, it is preferable to further include: an accumulator for increasing the flow rate of the action fluid supplied to the head chamber; a first flow path for supplying the action fluid to the accumulator using the hydraulic pump; a second flow path for supplying the action fluid to the head chamber using the accumulator; a third flow path for discharging the action fluid from the rod chamber and having the flow control valve; and a fourth flow path for supplying the action fluid to the head chamber using the hydraulic pump, which is different from the first flow path; the control unit uses the hydraulic pump and the fourth flow path to supply the action fluid to the head chamber.

[0022] A molding machine according to one embodiment of the present invention comprises: the above-mentioned injection device; a mold closing device for closing a metal mold; and an ejection device for ejecting a molded article from the metal mold; wherein the injection device injects liquid material into the metal mold.

[0023] A method for controlling a molding machine according to a technical solution of the present invention, the molding machine comprising: a mold closing device for closing a metal mold; an ejection device for ejecting a molded article from the metal mold; and an injection device for injecting liquid material into the metal mold using a plunger; the injection device comprising: an injection cylinder including a rod slidable to be connected to the plunger slidably in a sleeve, a piston fixed to the rod, a cylinder slidably housing the piston, a rod-side chamber disposed of the rod, and a head-side chamber located on the opposite side of the rod-side chamber, sandwiching the piston therebetween; a hydraulic pump for variable discharge of a working fluid; and a flow control valve for controlling the flow rate of the working fluid discharged from the rod-side chamber; in the control method of the molding machine, when the piston is advanced toward the rod side, the discharge of the working fluid from the hydraulic pump is controlled while the flow control valve is open, so that the supply of the working fluid to the head-side chamber varies in a manner that increases continuously or in stages.

[0024] In the control method of the molding machine of the above technical solution, it is preferable to change the amount of the pumping fluid of the hydraulic pump.

[0025] In the control method of the molding machine of the above technical solution, it is preferred that the injection device further includes a pressure sensor for measuring the pressure of the action fluid in the head chamber; and the change in the amount of action fluid discharged by the hydraulic pump is changed based on the pressure of the action fluid in the head chamber measured by the pressure sensor.

[0026] In the control method of the molding machine described above, it is preferable to reduce the change in the amount of the hydraulic pump discharging the operating fluid when the pressure of the operating fluid in the head chamber, as measured by the pressure sensor, reaches a predetermined pressure.

[0027] In the control method of the molding machine of the above technical solution, it is preferred to push out the molded article formed in the metal mold by moving the piston forward toward the rod side.

[0028] In the control method of the molding machine of the above technical solution, it is preferred that the injection device further includes a position sensor for measuring the position of the rod or the piston; based on the position of the rod or the piston measured by the position sensor, the amount of change in the amount of the hydraulic pump's pumping fluid is changed.

[0029] In the control method of the molding machine of the above technical solution, it is preferable to change the amount of change in the amount of the hydraulic pump's pumping fluid based on the speed of the rod or piston calculated according to the position of the rod or piston measured by the position sensor.

[0030] Invention Effects

[0031] According to the present invention, an injection device, a molding machine, and a method for controlling the molding machine are provided that can suppress the rapid ejection of the piston. Attached Figure Description

[0032] Figure 1 This is a schematic diagram showing the overall structure of the molding machine according to the first embodiment.

[0033] Figure 2 This is a schematic diagram showing the structure of the injection device according to the first embodiment.

[0034] Figure 3 This is an explanatory diagram of the control method of the molding machine according to the first embodiment.

[0035] Figure 4 This is an explanatory diagram of the control method of the molding machine according to the first embodiment.

[0036] Figure 5 This is an explanatory diagram of the control method of the molding machine according to the first embodiment.

[0037] Figure 6 This is an explanatory diagram of the control method of the molding machine according to the first embodiment.

[0038] Figure 7 This is an explanatory diagram of the control method of the molding machine according to the first embodiment.

[0039] Figure 8 This is an explanatory diagram of the control method of the molding machine in the comparative example of the first embodiment.

[0040] Figure 9 This is an explanatory diagram of the control method of the molding machine in a modified example of the first embodiment.

[0041] Figure 10 This is a schematic diagram showing the structure of the injection device according to the second embodiment.

[0042] Figure 11 This is an explanatory diagram of the control method for the molding machine according to the second embodiment.

[0043] Figure 12 This is an explanatory diagram of the control method for the molding machine according to the second embodiment.

[0044] Figure 13 This is an explanatory diagram of the control method for the molding machine according to the second embodiment.

[0045] Figure 14 This is an explanatory diagram of the control method for the molding machine according to the second embodiment. Detailed Implementation

[0046] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0047] Furthermore, in this specification, hydraulic pressure is used as an example of hydraulic system. For example, an oil pump is used as an example of hydraulic pump. In addition to oil pressure, water pressure may also be used, for example. Moreover, in this specification, operating oil is used as an example of operating fluid.

[0048] (First Embodiment)

[0049] The injection apparatus of the first embodiment includes: an injection cylinder comprising a rod that can be connected to a plunger that slides in a sleeve, a piston fixed to the rod, a cylinder that slidably houses the piston, a rod-side chamber on which the rod is disposed, and a head-side chamber located on the opposite side of the rod-side chamber with the piston sandwiched between them; a hydraulic pump; a flow control valve for controlling the flow rate of the operating fluid discharged from the rod-side chamber; and a control unit that, when the piston is moved toward the rod side, controls the amount of operating fluid discharged by the hydraulic pump while the flow control valve is open, so that the amount of operating fluid supplied to the head-side chamber varies in a manner that increases continuously or in stages.

[0050] The molding machine of the first embodiment includes: the above-described injection device; a mold closing device for closing a metal mold; and an ejection device for ejecting a molded article from the metal mold; wherein the injection device injects liquid material into the metal mold.

[0051] Figure 1 This is a schematic diagram showing the overall structure of the molding machine according to the first embodiment. Figure 1 This is a side view that includes a sectional view in one part. The molding machine in the first embodiment is a die casting machine 100. The die casting machine 100 is, for example, a cold chamber type die casting machine.

[0052] The die-casting machine 100 includes a mold closing device 10, an ejection device 12, an injection device 14, a metal mold 18, and a control unit 20.

[0053] The die-casting machine 100 includes a base 22, a fixed template 24, a movable template 26, a connecting rod housing 28, a tie rod 30, a sleeve 31, and a plunger 33. The plunger 33 has a top core 33a and a plunger rod 33b.

[0054] Die-casting machine 100 is operated by injecting material into the interior of metal mold 18. Figure 1 A die-casting machine is a machine that injects and fills a cavity (Ca) with liquid metal (molten metal) and allows the liquid metal to solidify within a metal mold (18) to produce a die-cast product (molten part). Examples of metals include aluminum, aluminum alloys, zinc alloys, or magnesium alloys. Liquid metal (molten metal) is an example of a liquid material.

[0055] The metal mold 18 includes a fixed metal mold 18a and a movable metal mold 18b. The metal mold 18 is located between the mold closing device 10 and the injection device 14.

[0056] The fixed template 24 is fixed on the base 22. The fixed template 24 is able to hold the fixed metal mold 18a.

[0057] The movable template 26 is movably mounted on the base 22 in the mold opening and closing direction. The mold opening and closing direction refers to... Figure 1 The mold opening direction and the mold closing direction are shown. The movable template 26 can hold the movable metal mold 18b against the fixed metal mold 18a.

[0058] The connecting rod housing 28 is mounted on the base 22. One end of the connecting rod mechanism constituting the mold clamping device 10 is fixed to the connecting rod housing 28.

[0059] The fixed template 24 and the connecting rod housing 28 are secured by the tie rod 30. During the application of the closing force to the fixed metal mold 18a and the movable metal mold 18b, the tie rod 30 supports the closing force.

[0060] The mold closing device 10 has the function of opening and closing the metal mold 18 and closing the mold.

[0061] The injection device 14 has the function of injecting molten metal into the cavity Ca of the metal mold 18 and pressurizing the molten metal. The injection device 14 has a rod 80 that can be connected to a plunger 33 that slides in the sleeve 31.

[0062] The ejection device 12 has the function of ejecting the manufactured die-cast product from the metal mold 18.

[0063] The sleeve 31 extends into the cavity Ca of the metal mold 18. The sleeve 31 is, for example, a cylindrical component connected to the fixed metal mold 18a. The sleeve 31 is, for example, cylindrical in shape.

[0064] The plunger 33 slides within the sleeve 31. The plunger 33 includes a top core 33a and a plunger rod 33b. The top core 33a, fixed to the front end of the plunger rod 33b, slides in the sleeve 31 in the front-rear direction. By sliding the top core 33a forward within the sleeve 31, the molten metal in the sleeve 31 is pushed into the metal mold 18.

[0065] The control unit 20 includes a control device 32, an input device 34, and a display device 36. The control unit 20 has the function of controlling the molding operation of the die-casting machine 100 using the mold clamping device 10, the ejection device 12, and the injection device 14.

[0066] The input device 34 accepts input from the operator. The operator can use the input device 34 to set the molding conditions of the die-casting machine 100, etc. The input device 34 is, for example, a touch panel of an LCD or OLED display.

[0067] The display device 36 displays, for example, the molding conditions and operating status of the die-casting machine 100 on a screen. The display device 36 is, for example, a liquid crystal display or an organic EL display.

[0068] The control device 32 has the function of performing various calculations and outputting control commands to various parts of the die-casting machine 100. For example, the control device 32 has the function of storing molding conditions. For example, the control device 32 controls the operation of the injection unit 14.

[0069] The control device 32 may be composed of a combination of hardware and software. The control device 32 may include, for example, a CPU (Central Processing Unit), a semiconductor memory, and a control program stored in the semiconductor memory.

[0070] Figure 2 This is a schematic diagram showing the structure of the injection device according to the first embodiment.

[0071] The injection device 14, for example, has the function of injecting and filling the cavity Ca in the metal mold 18 with molten metal from the sleeve 31. The injection device 14, for example, has the function of ejecting the die-cast product from the metal mold 18. The injection device 14, for example, has the function of moving the plunger 33 in the sleeve 31 during maintenance of the die-casting machine 100.

[0072] The injection device 14 includes an injection cylinder 44, a hydraulic pump 46, an oil tank 48, an accumulator 50, a position sensor 52, a pressure sensor 53, an injection valve 54, a speed control valve 56 (flow control valve), a direction switching valve 58, a first on / off valve 60, a second on / off valve 62, a filling valve 64, a first flow path 70a, a second flow path 70b, a third flow path 70c, a fourth flow path 70d, a fifth flow path 70e, a sixth flow path 70f, and a controller 72 (control unit). The hydraulic pump 46 is an example of a hydraulic pump. The speed control valve 56 is an example of a flow control valve. The controller 72 is an example of a control unit.

[0073] The injection cylinder 44 includes a rod 80, an injection piston 82 (piston), a cylinder barrel 84, a rod-side chamber 86, and a head-side chamber 88. The injection piston 82 is an example of a piston.

[0074] Rod 80 can be connected to plunger 33, which slides in sleeve 31. By moving rod 80, plunger 33 moves in sleeve 31.

[0075] The injection piston 82 is fixed to the rod 80. The injection piston 82 is slidably housed in the cylinder 84. The injection piston 82 is, for example, cylindrical.

[0076] The cylinder 84 slidably houses the injection piston 82. The cylinder 84 is, for example, cylindrical.

[0077] A rod-side chamber 86 is provided inside the cylinder 84 on the rod 80 side. The rod 80 is disposed in the rod-side chamber 86.

[0078] A head chamber 88 is provided inside the cylinder 84 on the side opposite to the rod 80. The injection piston 82 is sandwiched between the head chamber 88 and the rod chamber 86 and is located on the opposite side of the rod chamber 86.

[0079] The hydraulic pump 46 is driven, for example, by a pump motor (not shown). The hydraulic pump 46 has the function of drawing in and discharging operating oil from the oil tank 48. The hydraulic pump 46 contributes, for example, to the supply of operating oil to the accumulator 50 and to the injection cylinder 44.

[0080] The discharge volume or discharge pressure of the operating oil discharged by the hydraulic pump 46 is variable. The hydraulic pump 46 is, for example, a variable capacity pump. The variable capacity pump can change the discharge volume and discharge pressure of the operating oil.

[0081] Oil tank 48 stores, for example, the operating oil supplied to accumulator 50 or injection cylinder 44. Furthermore, oil tank 48 can recover, for example, the operating oil used by accumulator 50 or injection cylinder 44.

[0082] Accumulator 50 has the function of increasing the flow rate of the operating oil supplied to the head chamber 88. Accumulator 50 uses high-pressure sealed gas to store energy, and increases the flow rate of the operating oil by releasing this energy instantaneously. By setting accumulator 50, injection cylinder 44 can be operated at high speed.

[0083] The first flow path 70a connects the hydraulic pump 46 to the accumulator 50. Using the first flow path 70a, hydraulic oil can be supplied from the hydraulic pump 46 to the accumulator 50, filling the accumulator 50 with hydraulic oil and accumulating pressure.

[0084] Furthermore, the first flow path 70a is connected to the head chamber 88 via the second flow path 70b. During the injection operation of the injection cylinder 44, the first flow path 70a can be used to replenish the operating oil to the second flow path 70b.

[0085] The sixth flow path 70f connects the hydraulic pump 46 to the head chamber 88 via the fourth flow path 70d. The sixth flow path 70f is the so-called pump line. Using the sixth flow path 70f and the fourth flow path 70d, hydraulic oil can be supplied from the hydraulic pump 46 to the head chamber 88. The fourth flow path 70d is different from the first flow path 70a.

[0086] Furthermore, the sixth flow path 70f connects the hydraulic pump 46 to the rod-side chamber 86 via the fifth flow path 70e. Using the sixth flow path 70f and the fifth flow path 70e, hydraulic oil can be supplied from the hydraulic pump 46 to the rod-side chamber 86.

[0087] The third flow path 70c connects the rod-side chamber 86 to the oil tank 48. Using the third flow path 70c, the operating oil discharged from the rod-side chamber 86 can be recovered into the oil tank 48.

[0088] The first flow path 70a to the sixth flow path 70f are, for example, made of steel pipe or hose.

[0089] An injection valve 54 is provided in the second flow path 70b. The injection valve 54 is located between the head chamber 88 and the accumulator 50. The injection valve 54 allows or cuts off the supply of operating oil from the accumulator 50 to the head chamber 88.

[0090] The injection valve 54 is, for example, a pilot-operated check valve that allows the flow of operating oil from the accumulator 50 to the head chamber 88 when no pilot pressure is introduced, and cuts off the flow in the opposite direction. When pilot pressure is introduced into the injection valve 54, both flows are cut off. The injection valve 54 has the function of preventing backflow of operating oil from the head chamber 88 to the accumulator 50.

[0091] When the injection valve 54 is in the open position, the flow of operating oil from the accumulator 50 to the head chamber 88 is permitted. When the injection valve 54 is in the closed position, the flow of operating oil from the accumulator 50 to the head chamber 88 is cut off.

[0092] Speed ​​control valve 56 is located in the third flow path 70c. Speed ​​control valve 56 is located between the rod side chamber 86 and the oil tank 48. Speed ​​control valve 56 controls the flow rate of the operating oil discharged from the rod side chamber 86 to the oil tank 48.

[0093] The forward speed of the injection piston 82 is controlled by controlling the flow rate of the actuating oil via the speed control valve 56. The speed control valve 56 performs so-called outlet throttling control. When the speed control valve 56 is closed, the flow of actuating oil between the rod-side chamber 86 and the oil tank 48 is cut off.

[0094] The type of speed control valve 56 is not particularly limited as long as it can control the flow rate of the operating oil. For example, the speed control valve 56 can be a pressure-compensated valve or a non-pressure-compensated valve. Furthermore, the speed control valve 56 can be, for example, a servo valve subject to feedback control or a proportional valve subject to open-circuit control.

[0095] The directional switching valve 58 is located between the sixth flow path 70f and the fourth flow path 70d, and between the sixth flow path 70f and the fifth flow path 70e. The directional switching valve 58 is located between the head side chamber 88 and the hydraulic pump 46, and between the rod side chamber 86 and the hydraulic pump 46.

[0096] The directional switching valve 58 has the function of switching the flow path of the operating oil supplied from the hydraulic pump 46 via the sixth flow path 70f between the fourth flow path 70d and the fifth flow path 70e. The directional switching valve 58 also has the function of switching the supply target of the operating oil supplied from the hydraulic pump 46 between the head side chamber 88 and the rod side chamber 86.

[0097] For example, by supplying actuating oil to the head-side chamber 88, the injection piston 82 advances. Furthermore, for example, by supplying actuating oil to the rod-side chamber 86, the injection piston 82 retracts.

[0098] The type of directional switching valve 58 is not particularly limited as long as it can switch the flow direction of the operating oil supplied from the hydraulic pump 46. For example, the directional switching valve 58 is an electromagnetic switching valve that uses an electromagnet to move the spool valve core.

[0099] The first on / off valve 60 is located in the fourth flow path 70d. The first on / off valve 60 is located between the head side chamber 88 and the directional switching valve 58. The first on / off valve 60 allows or cuts off the flow of operating oil between the directional switching valve 58 and the head side chamber 88.

[0100] When the first on / off valve 60 is in the open state, the flow of operating oil between the directional switching valve 58 and the head chamber 88 is permitted. When the first on / off valve 60 is in the closed state, the flow of operating oil between the directional switching valve 58 and the head chamber 88 is cut off.

[0101] The type of the first on / off valve 60 is not limited as long as it can allow and cut off the flow of operating oil.

[0102] The second on / off valve 62 is located in the fifth flow path 70e. The second on / off valve 62 is located between the rod-side chamber 86 and the direction switching valve 58. The second on / off valve 62 allows or cuts off the flow of operating oil between the direction switching valve 58 and the rod-side chamber 86.

[0103] When the second on / off valve 62 is in the open state, the flow of operating oil between the directional switching valve 58 and the rod-side chamber 86 is permitted. When the second on / off valve 62 is in the closed state, the flow of operating oil between the directional switching valve 58 and the rod-side chamber 86 is cut off.

[0104] The type of the second on / off valve 62 is not particularly limited as long as it can allow and cut off the flow of operating oil.

[0105] A filling valve 64 is located in the first flow path 70a. The filling valve 64 is located between the accumulator 50 and the hydraulic pump 46. The filling valve 64 is located between the head chamber 88 and the hydraulic pump 46.

[0106] The filling valve 64, for example, allows or cuts off the flow of operating oil between the accumulator 50 and the hydraulic pump 46. The filling valve 64, for example, allows or cuts off the flow of operating oil between the head chamber 88 and the hydraulic pump 46.

[0107] The type of filling valve 64 is not particularly limited as long as it can allow and cut off the flow of operating oil.

[0108] The position sensor 52 has the function of detecting the position of the rod 80. The position sensor 52 is, for example, an optical or magnetic linear encoder. By differentiating the position of the rod 80 detected by the position sensor 52, the speed of the rod 80 can be detected.

[0109] Pressure sensor 53 has the function of measuring the pressure of the operating oil in the head side chamber 88.

[0110] The controller 72 controls, for example, the operation of the injection cylinder 44, the hydraulic pump 46, the oil tank 48, the accumulator 50, the injection valve 54, the speed control valve 56, the direction switching valve 58, the first opening and closing valve 60, the second opening and closing valve 62, and the filling and replenishing valve 64.

[0111] The controller 72 has, for example, the following function: when the injection piston 82 is moved toward the rod 80, with the speed control valve 56 open at a specified opening, it controls the amount of hydraulic oil discharged from the hydraulic pump 46, so that the amount of hydraulic oil supplied to the head chamber 88 changes in a continuous or phased manner.

[0112] The controller 72 has the function of changing the amount of hydraulic oil discharged from the hydraulic pump 46. In other words, it has the function of changing the amount of hydraulic oil discharged by the hydraulic pump 46 per unit time.

[0113] The controller 72, for example, has the function of changing the amount of discharge of the hydraulic pump 46 based on the pressure of the operating oil in the head chamber 88 measured by the pressure sensor 53. The controller 72, for example, also has the function of reducing the amount of change in the amount of operating oil discharged by the hydraulic pump 46 when the pressure of the operating oil in the head chamber 88 measured by the pressure sensor 53 reaches a predetermined pressure.

[0114] The controller 72, for example, has the function of controlling the supply of operating oil to the head chamber 88 using the hydraulic pump 46 and the fourth flow path 70d.

[0115] The controller 72 may be composed of a combination of hardware and software. The controller 72 may include, for example, a CPU, a semiconductor memory, and a control program stored in the semiconductor memory.

[0116] Controller 72 is, for example, part of control device 32.

[0117] Next, an example of the control method for the die-casting machine 100 will be described. In particular, the control method for the injection device 14 of the die-casting machine 100 will be described.

[0118] In the control method of the injection device 14 of the die casting machine 100, the case in which the manufactured die casting is ejected from the metal mold 18 by the injection device 14 is specifically described.

[0119] Regarding controls other than the control method of the injection device 14 of the die-casting machine 100, such as the control of the mold clamping device 10 or the ejection device 12, some descriptions are omitted.

[0120] Figure 3 This is an explanatory diagram of the control method of the molding machine according to the first embodiment.

[0121] When manufacturing die-cast products using the die-casting machine 100, the metal mold 18 is closed using the mold-closing device 10. For the cavity Ca inside the closed metal mold 18, molten liquid is injected and filled using the injection device 14.

[0122] After the molten metal solidifies, the die-cast part 99 is ejected and removed from the metal mold. At this time, as... Figure 3 As shown, the fixed metal mold 18a and the movable metal mold 18b are opened. By advancing the injection piston 82, the die-cast product 99 is ejected from the fixed metal mold 18a by the plunger 33. Then, the die-cast product 99 is ejected from the movable metal mold 18b using the ejection device 12.

[0123] Figure 4 , Figure 5 , Figure 6 and Figure 7 This is an explanatory diagram of the control method of the molding machine according to the first embodiment. Figure 4 It's a timeline. Figure 4 The pump output of the hydraulic pump 46, the command to supply the operating oil to the head chamber 88, the command to discharge the operating oil from the rod chamber 86, the pressure of the operating oil in the sixth flow path 70f of the pump circuit, and the time point in time at which the pressure of the operating oil in the head chamber 88 changes with time.

[0124] Figure 5 , Figure 6 and Figure 7 This is an explanatory diagram of the operation of the injection device 14 of the die-casting machine 100.

[0125] Figure 5 It means Figure 4 A diagram showing the state of the injection device 14 at time t0. Figure 5 This indicates the state of the injection device 14 after the molten material in the cavity Ca inside the metal mold 18 has solidified.

[0126] The hydraulic pump 46 is in a stopped state. The injection valve 54, the speed control valve 56 (flow control valve), the direction switching valve 58, the first on / off valve 60 and the second on / off valve 62, and the filling and replenishing valve 64 are set to the closed state.

[0127] Figure 6 It means Figure 4 A diagram showing the state of the injection device 14 at time t1.

[0128] The hydraulic pump 46 operates upon commands from the controller 72. The amount of hydraulic oil discharged from the hydraulic pump 46 varies in a continuously increasing manner. Alternatively, the amount of hydraulic oil discharged from the hydraulic pump 46 varies in a gradually increasing manner.

[0129] Actuating oil is supplied to the head chamber 88 by a command from the controller 72. Specifically, for example, the directional switching valve 58 is operated such that the actuating oil supplied from the hydraulic pump 46 is directed to the head chamber 88 by a command from the controller 72.

[0130] Furthermore, the actuating oil can be discharged from the rod-side chamber 86 via a command from the controller 72. Specifically, for example, the speed control valve 56 can be opened to a predetermined degree via a command from the controller 72, thereby discharging the actuating oil from the rod-side chamber 86.

[0131] The first on / off valve 60 is set to the open state via a command from the controller 72. The injection valve 54, the second on / off valve 62, and the filling / replenishing valve 64 are set to the closed state. The white arrows indicate the flow of operating oil.

[0132] Figure 7 It means Figure 4 A diagram showing the state of the injection device 14 from time t2 to t4.

[0133] At time t2, the operating oil fills the head chamber 88, and the pressure of the operating oil in the sixth flow path 70f of the pump circuit and the pressure of the operating oil in the head chamber 88 begin to increase. The pressure of the operating oil in the head chamber 88 is measured, for example, by pressure sensor 53.

[0134] After time t2, the actuating oil is discharged from the rod-side chamber 86, and the injection piston 82 advances towards the rod 80. The rod 80, which is fixed to the injection piston 82, and the plunger 33, which is fixed to the rod 80, also advance. Through the advance of the plunger 33, the die-cast product 99 is pushed out by the plunger 33 and detaches from the fixed metal mold 18a.

[0135] For example, if the pressure of the operating oil in the head chamber 88, as measured by the pressure sensor 53, reaches a predetermined pressure Px at time t3, the change in the amount of operating oil discharged from the hydraulic pump 46 is reduced by a command from the controller 72. In other words, the discharge amount per unit time of the hydraulic pump 46 is reduced.

[0136] Feedback control is implemented by feeding back the pressure of the actuating oil in the head chamber 88, measured by pressure sensor 53, to the change in the amount of actuating oil discharged from hydraulic pump 46.

[0137] Next, the function and effect of the injection device 14, the die casting machine 100, and the control method of the die casting machine 100 in the first embodiment will be explained.

[0138] In die-casting machines, an injection cylinder is also used to eject the die-casting part from the metal mold. By advancing the injection piston, the die-casting part is pushed out by the plunger and detached from the metal mold. If the injection piston flies out abruptly during the ejection of the die-casting part from the metal mold, a pressure shock occurs. This pressure shock can potentially damage the die-casting part or the structure of the die-casting machine.

[0139] Figure 8 This is an explanatory diagram of the control method of the molding machine in the comparative example of the first embodiment. Figure 8 It's a timeline.

[0140] The molding machine of the comparative example of the first embodiment has the same structure as the die-casting machine 100 of the first embodiment, except for the controller 72.

[0141] Figure 8The pump output of the hydraulic pump 46, the command to supply the operating oil to the head chamber 88, the command to discharge the operating oil from the rod chamber 86, the pressure of the operating oil in the sixth flow path 70f of the pump circuit, and the time point in time at which the pressure of the operating oil in the head chamber 88 changes with time. Figure 8 Is with Figure 4 The corresponding diagram.

[0142] At time t0, the molten Ca in the cavity within the metal mold 18 solidifies. The hydraulic pump 46 is stopped. The injection valve 54, speed control valve 56 (flow control valve), direction switching valve 58, first on / off valve 60, second on / off valve 62, and filling valve 64 are all closed.

[0143] At time t1, hydraulic pump 46 begins operation. The amount of operating oil discharged from hydraulic pump 46 becomes constant after time t1. At time t1, injection valve 54, speed control valve 56 (flow control valve), directional switching valve 58, first on / off valve 60, second on / off valve 62, and filling valve 64 are closed. Because directional switching valve 58 and first on / off valve 60 are closed, the pressure of the operating oil in the sixth flow path 70f of the pump circuit increases over time.

[0144] At time t2, via a command from controller 72, direction switching valve 58 actuates to direct the supply of operating oil from hydraulic pump 46 to head side chamber 88. Furthermore, via a command from controller 72, first on / off valve 60 is also opened. Additionally, via a command from controller 72, speed control valve 56 opens to a predetermined degree, allowing operating oil to be discharged from rod side chamber 86.

[0145] Immediately following time t2, the pressure of the actuating oil in the head chamber 88 rises sharply, causing the injection piston 82 to fly out abruptly, resulting in a pressure shock. This pressure shock may damage the die-cast product or the structure of the die-casting machine.

[0146] In the first embodiment, the die-casting machine 100, under the control of the controller 72, continuously increases the amount of operating oil discharged from the hydraulic pump 46. In other words, the amount of operating oil discharged from the hydraulic pump 46 gradually changes.

[0147] Therefore, the rapid increase in the pressure of the operating oil in the head chamber 88 is suppressed. Consequently, the rapid ejection of the injection piston 82 is suppressed, reducing the pressure shock that occurs. Thus, damage to the die-cast product 99 and damage to the structure of the die-casting machine 100 are suppressed.

[0148] From the viewpoint of reducing pressure shocks, it is preferable to implement feedback control that feeds back the pressure of the operating oil in the head chamber 88, measured by the pressure sensor 53, to the change in the amount of operating oil discharged from the hydraulic pump 46. For example, it is preferable to reduce the change in the amount of operating oil discharged from the hydraulic pump 46 when the pressure of the operating oil in the head chamber 88 reaches a predetermined pressure Px.

[0149] Figure 9 This is an explanatory diagram of the control method of the molding machine in a modified example of the first embodiment. Figure 9 It's a timeline. Figure 9 Is with Figure 4 The corresponding diagram.

[0150] The molding machine of the modified embodiment of the first embodiment differs from the die-casting machine 100 of the first embodiment in that it does not perform feedback control. Since the molding machine of the modified embodiment of the first embodiment does not perform feedback control, the construction of the injection device 14 is simplified.

[0151] According to a variation of the first embodiment, similar to the first embodiment, the rapid ejection of the injection piston 82 is suppressed, and the pressure shock that occurs is reduced.

[0152] According to the first embodiment, an injection apparatus, a molding machine, and a method for controlling the molding machine can be provided that can suppress the rapid ejection of the piston, suppress damage to the molded article, and suppress damage to the structure of the die-casting machine.

[0153] (Second Implementation)

[0154] The injection device of the second embodiment differs from the injection device of the first embodiment in that the control unit changes the amount of hydraulic pump fluid dispensed based on the position of the rod or cylinder measured by the position sensor. Hereinafter, some descriptions that are repeated in the first embodiment will be omitted.

[0155] The molding machine of the second embodiment differs from the molding machine of the first embodiment in that the injection device is different.

[0156] The molding machine in the second embodiment is a die casting machine 200. The die casting machine 200 is, for example, a cold chamber type die casting machine.

[0157] The die-casting machine 200 includes a mold closing device 10, an ejection device 12, an injection device 15, a metal mold 18, and a control unit 20.

[0158] Figure 10 This is a schematic diagram showing the structure of the injection device according to the second embodiment.

[0159] The injection device 15 includes an injection cylinder 44, a hydraulic pump 46, an oil tank 48, an accumulator 50, a position sensor 52, a pressure sensor 53, an injection valve 54, a speed control valve 56 (flow control valve), a direction switching valve 58, a first on / off valve 60, a second on / off valve 62, a filling valve 64, a first flow path 70a, a second flow path 70b, a third flow path 70c, a fourth flow path 70d, a fifth flow path 70e, a sixth flow path 70f, and a controller 72 (control unit). The hydraulic pump 46 is an example of a hydraulic pump. The speed control valve 56 is an example of a flow control valve. The controller 72 is an example of a control unit.

[0160] The injection cylinder 44 includes a rod 80, an injection piston 82 (piston), a cylinder barrel 84, a rod-side chamber 86, and a head-side chamber 88. The injection piston 82 is an example of a piston.

[0161] The controller 72 controls, for example, the operation of the injection cylinder 44, the hydraulic pump 46, the oil tank 48, the accumulator 50, the injection valve 54, the speed control valve 56, the direction switching valve 58, the first opening and closing valve 60, the second opening and closing valve 62, and the filling and replenishing valve 64.

[0162] The controller 72 has, for example, the following function: when the injection piston 82 is moved forward toward the rod 80, with the speed control valve 56 open at a specified opening, it controls the amount of hydraulic oil discharged from the hydraulic pump 46, so that the amount of hydraulic oil supplied to the head chamber 88 changes in a continuous or phased manner.

[0163] The controller 72 has the function of changing the amount of hydraulic oil discharged from the hydraulic pump 46. In other words, it has the function of changing the amount of hydraulic oil discharged by the hydraulic pump 46 per unit time.

[0164] The controller 72, for example, has the function of changing the amount of hydraulic pump 46 pumped out based on the change in the position of rod 80 or injection piston 82 measured by position sensor 52. The controller 72, for example, has the function of changing the amount of hydraulic pump 46 pumped out based on the speed of rod 80 or injection piston 82 calculated according to the position of rod 80 or injection piston 82 measured by position sensor 52.

[0165] Next, an example of the control method for the die-casting machine 200 will be described. In particular, the control method for the injection device 15 of the die-casting machine 200 will be described.

[0166] In the control method of the injection device 15 of the die casting machine 200, the case of moving the plunger 33 in the sleeve 31 by using the injection device 15 during the maintenance of the die casting machine 200 is explained in particular.

[0167] Regarding controls other than the control method of the injection device 15 of the die casting machine 200, such as the control of the mold clamping device 10 and the ejection device 12, some descriptions will be omitted.

[0168] Figure 11 This is an explanatory diagram of the control method for the molding machine according to the second embodiment.

[0169] When performing maintenance on die-casting machine 200, such as Figure 11 As shown, the plunger 33 inside the sleeve 31 is moved using the injection device 15. At this time, there is no molten material inside the sleeve 31. Furthermore, there is no die-casting material in the metal mold 18.

[0170] Figure 12 This is an explanatory diagram of the control method for the molding machine according to the second embodiment. Figure 12 It's a timeline. Figure 12 The pump output of the hydraulic pump 46, the command to supply the operating oil to the head chamber 88, the command to discharge the operating oil from the rod chamber 86, the pressure of the operating oil in the sixth flow path 70f of the pump circuit, and the time point in time at which the speed of the rod 80 changes with time.

[0171] At time t0, the injection piston 82 and plunger 33 are stationary. The hydraulic pump 46 is stopped. The injection valve 54, the speed control valve 56 (flow control valve), the direction switching valve 58, the first on / off valve 60 and the second on / off valve 62, and the filling valve 64 are closed.

[0172] At time t1, the hydraulic pump 46 starts operating upon instruction from the controller 72. The amount of hydraulic oil discharged from the hydraulic pump 46 varies in a continuously increasing manner.

[0173] Actuating oil is supplied to the head chamber 88 via a command from the controller 72. Specifically, for example, the directional switching valve 58 is activated via a command from the controller 72 to direct the supply of actuating oil from the hydraulic pump 46 to the head chamber 88.

[0174] Furthermore, the actuating oil can be discharged from the rod-side chamber 86 via a command from the controller 72. Specifically, for example, the speed control valve 56 can be opened to a predetermined degree via a command from the controller 72, thereby discharging the actuating oil from the rod-side chamber 86.

[0175] The first on / off valve 60 is set to the open state by a command from the controller 72. The injection valve 54, the second on / off valve 62, and the filling / replenishing valve 64 are set to the closed state.

[0176] At time t2, the operating oil fills the head chamber 88, and the pressure of the operating oil in the sixth flow path 70f of the pump circuit begins to increase.

[0177] After time t2, the actuating oil is discharged from the rod-side chamber 86, and the injection piston 82 advances towards the rod 80. The rod 80, which is fixed to the injection piston 82, and the plunger 33, which is fixed to the rod 80, also advance.

[0178] For example, at time t3, the change in the amount of hydraulic oil discharged from the hydraulic pump 46 changes. This change in the amount of hydraulic oil discharged from the hydraulic pump 46 is based on the velocity of the rod 80 calculated from the position of the rod 80 measured by the position sensor 52.

[0179] For example, when the speed of lever 80 reaches a predetermined speed Vx, the change in the amount of hydraulic oil discharged from hydraulic pump 46 is increased by a command from controller 72. In other words, the discharge amount per unit time of hydraulic pump 46 is increased.

[0180] By increasing the change in the amount of actuating oil discharged from the hydraulic pump 46, the change in the speed of the lever 80 also increases. The gradient of the speed change of the lever 80 becomes steeper.

[0181] Feedback control is implemented by feeding back the speed of rod 80, calculated based on the speed measured by position sensor 52, to the change in the amount of actuating oil ejected from hydraulic pump 46.

[0182] For example, after time t4, the amount of actuating oil discharged from hydraulic pump 46 is set to a constant. After time t4, the speed of lever 80 becomes constant.

[0183] Next, the function and effect of the injection device 15, the die casting machine 100, and the control method of the die casting machine 100 in the second embodiment will be explained.

[0184] In die-casting machines, injection cylinders are also used, for example, during machine maintenance. For instance, an injection cylinder is used to move a plunger within a sleeve. If the injection piston flies out abruptly during this movement, the accuracy of plunger position control decreases. For example, the micro-motion accuracy of the plunger deteriorates.

[0185] Figure 13 This is an explanatory diagram of the control method of the molding machine in the comparative example of the second embodiment. Figure 13 It's a timeline.

[0186] The molding machine of the comparative example of the second embodiment has the same structure as the die-casting machine 200 of the second embodiment, except for the controller 72.

[0187] Figure 13 The pump output of the hydraulic pump 46, the command to supply the operating oil to the head chamber 88, the command to discharge the operating oil from the rod chamber 86, the pressure of the operating oil in the sixth flow path 70f of the pump circuit, and the time point in time at which the speed of the rod 80 changes with time. Figure 13 Is with Figure 12 The corresponding diagram.

[0188] At time t0, the injection piston 82 and plunger 33 are stationary. At time t0, the hydraulic pump 46 is stopped. The injection valve 54, speed control valve 56 (flow control valve), direction switching valve 58, first on / off valve 60 and second on / off valve 62, and filling valve 64 are set to the closed state.

[0189] At time t1, hydraulic pump 46 operates. The amount of operating oil discharged from hydraulic pump 46 is constant. At time t1, injection valve 54, speed control valve 56 (flow control valve), directional switching valve 58, first on / off valve 60 and second on / off valve 62, and filling valve 64 are in the closed state. Because directional switching valve 58 and first on / off valve 60 are in the closed state, the pressure of the operating oil in the sixth flow path 70f of the pump circuit increases with time.

[0190] At time t2, via a command from controller 72, direction switching valve 58 actuates to direct the supply of operating oil from hydraulic pump 46 to head chamber 88. Furthermore, first on / off valve 60 is also opened. Additionally, via a command from controller 72, speed control valve 56 opens to a predetermined degree, allowing operating oil to be discharged from rod chamber 86.

[0191] Immediately following time t2, the pressure of the actuating oil in the head chamber 88 rises sharply, causing the injection piston 82 to fly out rapidly. Consequently, the speed of the rod 80 changes drastically, and the accuracy of the plunger 33's position control decreases.

[0192] Furthermore, due to the time lag between the start of operation of the hydraulic pump 46 (time t1) and the supply of actuating oil to the head chamber 88 (time t2), the accuracy of the position control of the plunger 33 decreases.

[0193] In the second embodiment, the die-casting machine 200, under the control of the controller 72, varies the amount of operating oil discharged from the hydraulic pump 46 in a continuously increasing manner. In other words, the amount of operating oil discharged from the hydraulic pump 46 gradually changes.

[0194] Therefore, the rapid increase in the pressure of the actuating oil in the head chamber 88 is suppressed. Consequently, the rapid ejection of the injection piston 82 is suppressed, and the speed of the rod 80 changes gradually. As a result, the accuracy of the position control of the plunger 33 is improved.

[0195] Furthermore, because the time lag between the start of operation of the hydraulic pump 46 and the supply of actuating oil to the head chamber 88 is small, the position control accuracy of the plunger 33 is improved. For example, the micro-motion accuracy of the plunger 33 is improved.

[0196] From the viewpoint of shortening the time it takes for the plunger 33 to move to the desired position, it is preferable to perform feedback control on the change in the amount of actuating oil dispensed from the hydraulic pump 46, which is fed back to the speed of the rod 80 calculated based on the position of the rod 80 measured by the position sensor 52. For example, when the speed of the rod 80 reaches a predetermined speed Vx, it is preferable to increase the change in the amount of actuating oil dispensed from the hydraulic pump 46 via a command from the controller 72.

[0197] Figure 14 This is an explanatory diagram of the control method of the molding machine in a modified example of the second embodiment. Figure 14 It's a timeline. Figure 14 Is with Figure 12 The corresponding diagram.

[0198] The molding machine of the modified embodiment 2 differs from the die-casting machine 200 of the second embodiment in that it does not perform feedback control. Because the molding machine of the modified embodiment 2 does not perform feedback control, the construction of the injection device 15 is simplified.

[0199] According to a variation of the second embodiment, similar to the second embodiment, the rapid ejection of the injection piston 82 is suppressed, and the accuracy of the position control of the plunger 33 is improved.

[0200] According to the second embodiment, an injection device, a molding machine, and a control method for the molding machine can be provided that can suppress the rapid ejection of the piston and improve the accuracy of plunger position control.

[0201] In the first and second embodiments, a die-casting machine that fills molten metal into a metal mold was described as an example of a molding machine, but the present invention can also be applied to an injection molding machine that fills resin material into a metal mold.

[0202] Furthermore, the control unit of the injection device can be configured to have the functions of both the control units of the first and second embodiments.

[0203] The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In the embodiments, in the injection apparatus, molding machine, and control method of the molding machine, parts that are not directly needed in the description of the present invention have been omitted, but necessary elements related to the injection apparatus, molding machine, and control method of the molding machine may be appropriately selected and used.

[0204] In addition, all injection molding devices, molding machines, and control methods for molding machines that incorporate the elements of this invention and can be appropriately designed and modified by those skilled in the art are included within the scope of this invention. The scope of this invention is defined by the technical solutions and their equivalents.

[0205] Label Explanation

[0206] 10 Mold Closing Device

[0207] 12 Launching Device

[0208] 14 Injection Device

[0209] 15 Injection Devices

[0210] 18 metal mold

[0211] 31 sleeve

[0212] 33 plunger

[0213] 44 injection cylinder

[0214] 46 Hydraulic Pump

[0215] 50 accumulator

[0216] 52 position sensors

[0217] 53 Pressure Sensor

[0218] 56. Speed ​​control valve (flow control valve)

[0219] 70a 1st flow path

[0220] 70b 2nd flow path

[0221] 70c 3rd flow path

[0222] 70d 4th flow path

[0223] 72 Controller (Control Unit)

[0224] 80 strokes

[0225] 82 Injection Piston (Piston)

[0226] 84 cylinder barrel

[0227] 86-bar side chamber

[0228] 88 side chambers

[0229] 99% die-cast products (molded products)

[0230] 100 die casting machine

[0231] 200 die casting machine

[0232] Ca cavity

Claims

1. An injection device, characterized in that, have: The injection cylinder includes a rod that can be connected to a plunger that slides in a sleeve, a piston fixed to the rod, a cylinder that slidably houses the piston, a rod-side chamber on which the rod is disposed, and a head-side chamber on the opposite side of the rod-side chamber that sandwiches the piston. Hydraulic pump, the amount of actuating fluid discharged is variable; The flow control valve controls the flow rate of the actuating fluid discharged from the rod-side chamber and opens regardless of the pressure of the actuating fluid in the head-side chamber. as well as The control unit, while the piston is moving towards the rod side and the flow control valve is open, controls the amount of hydraulic fluid discharged from the hydraulic pump, so that the amount of hydraulic fluid supplied to the head chamber increases continuously or in stages.

2. The injection device as claimed in claim 1, characterized in that, The aforementioned control unit causes a change in the amount of fluid discharged from the aforementioned hydraulic pump.

3. The injection device as described in claim 2, characterized in that, It also includes a pressure sensor for measuring the pressure of the aforementioned action fluid in the head chamber. The control unit adjusts the amount of operating fluid discharged by the hydraulic pump based on the pressure of the operating fluid in the head chamber measured by the pressure sensor.

4. The injection device as described in claim 3, characterized in that, When the pressure of the operating fluid in the head chamber, as measured by the pressure sensor, reaches a predetermined pressure, the control unit reduces the change in the amount of operating fluid discharged by the hydraulic pump.

5. The injection device as described in claim 2, characterized in that, It also includes a position sensor that measures the position of the aforementioned rod or piston. The control unit adjusts the amount of hydraulic fluid pumped out based on the position of the rod or piston measured by the position sensor.

6. The injection device as described in claim 5, characterized in that, The control unit adjusts the amount of hydraulic fluid pumped out based on the speed of the rod or piston calculated from the position of the rod or piston measured by the position sensor.

7. The injection device according to any one of claims 1 to 6, characterized in that, It also has: An accumulator is used to increase the flow rate of the actuating fluid supplied to the head chamber. In the first flow path, the aforementioned hydraulic pump is used to supply the aforementioned operating fluid to the aforementioned accumulator; The second flow path uses the aforementioned accumulator to supply the aforementioned actuating fluid to the aforementioned head-side chamber; The third flow path discharges the aforementioned actuating fluid from the aforementioned rod-side chamber and includes the aforementioned flow control valve; and The fourth flow path uses the aforementioned hydraulic pump to supply the aforementioned actuating fluid to the aforementioned head side chamber, which is different from the aforementioned first flow path. The control unit uses the hydraulic pump and the fourth flow path to supply the operating fluid to the head chamber.

8. A molding machine, characterized in that, have: The injection device according to any one of claims 1 to 7; The mold closing device closes the metal mold; and An ejection device ejects the molded article from the aforementioned metal mold; The aforementioned injection device injects liquid material into the aforementioned metal mold.

9. A control method for a molding machine, wherein, The molding machine includes: The mold closing device closes the metal mold; An ejection device ejects the molded article from the aforementioned metal mold; as well as The injection device uses a plunger to inject liquid material into the aforementioned metal mold. The injection device includes: The injection cylinder includes a rod that can be connected to the plunger that slides in a sleeve, a piston fixed to the rod, a cylinder that slidably houses the piston, a rod-side chamber on which the rod is disposed, and a head-side chamber on the opposite side of the rod-side chamber that sandwiches the piston. Hydraulic pump with variable output of actuating fluid; and The flow control valve controls the flow rate of the actuating fluid discharged from the rod-side chamber and opens regardless of the pressure of the actuating fluid in the head-side chamber. The control method for the molding machine is characterized by the following: When the piston is moved forward toward the rod side, with the flow control valve open, the amount of hydraulic fluid discharged from the hydraulic pump is controlled so that the amount of hydraulic fluid supplied to the head chamber increases continuously or in stages.

10. The control method for the molding machine as described in claim 9, characterized in that, This causes a change in the amount of fluid discharged from the aforementioned hydraulic pump.

11. The control method for the molding machine as described in claim 10, characterized in that, The aforementioned injection device also includes a pressure sensor for measuring the pressure of the action fluid in the head chamber. The change in the amount of operating fluid discharged by the hydraulic pump is caused by the pressure of the operating fluid in the head chamber measured by the pressure sensor.

12. The control method for the molding machine as described in claim 11, characterized in that, When the pressure of the operating fluid in the head chamber, as measured by the pressure sensor, reaches a predetermined pressure, the change in the amount of operating fluid discharged by the hydraulic pump is reduced.

13. The control method for the molding machine as described in claim 10 or 11, characterized in that, By advancing the piston toward the rod side, the molded article formed in the metal mold is ejected.

14. The control method for the molding machine as described in claim 10, characterized in that, The aforementioned injection device also includes a position sensor for measuring the position of the rod or piston. The change in the amount of actuating fluid discharged by the hydraulic pump is caused by the position of the rod or piston measured by the position sensor.

15. The control method for the molding machine as described in claim 14, characterized in that, The change in the amount of hydraulic fluid discharged by the hydraulic pump is caused by calculating the speed of the rod or piston based on the position of the rod or piston measured by the position sensor.

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