JP2022091590A - Die-cast machine - Google Patents

Abstract

To provide a die-cast machine capable of preventing a plunger from abruptly rushing out in injection-advancement processing.SOLUTION: A die-cast machine executes pressurization processing that pressurizes an interior of a rod chamber (38) by placing a restriction valve (46) at a first feed position, a check valve (48) at a second close position and a servo valve (54) at a brake position, and injection-advancement processing that advances a plunger by placing the check valve (48) at a second feed position and the opening of the servo valve (54) at a first degree after the interior of the rod chamber (38) reaches predetermined pressure in the pressurization processing.SELECTED DRAWING: Figure 2

Description

The present invention relates to a die casting machine that injects molten metal into a mold to form a molded product.

Conventionally, a die casting machine including a plunger arranged in a sleeve communicating with a cavity of a mold and a hydraulic cylinder for advancing and retracting the plunger in the sleeve has been known (see, for example, Patent Document 1).

Further, there is also a die casting machine in which a servo valve as described in Patent Document 2 is arranged in a return oil passage from a rod chamber of a hydraulic cylinder to a hydraulic oil tank to control the forward speed of a plunger.

More specifically, by supplying hydraulic oil of a predetermined pressure to the head chamber of the hydraulic cylinder and adjusting the spool opening of the servo valve, the plunger advances in the sleeve at a predetermined forward speed to form a mold. Inject molten metal (hereinafter referred to as "injection advance processing").

Japanese Unexamined Patent Publication No. 2019-155478 Japanese Unexamined Patent Publication No. 54-6775

In the die casting machine having the above configuration, if the injection forward processing is started while the pressure in the rod chamber is low, the plunger suddenly pops out. As a result, there is a problem that the waviness of the molten metal in the sleeve becomes large and air is entrained, and entrainment cavities or the like are generated in the molded product.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a die casting machine capable of preventing a sudden jumping out of a plunger in an injection forward processing.

In order to solve the above problems, the present invention supplies the molten metal in the sleeve to the cavity by advancing toward the cavity in the sleeve and a sleeve communicating with the cavity formed in the mold. A hydraulic cylinder that advances the plunger by supplying hydraulic oil to the head chamber and retracts the plunger by supplying hydraulic oil to the rod chamber, and operates the head chamber and the rod chamber. It is a die casting machine provided with a hydraulic circuit for supplying and discharging oil and a control device for controlling the operation of the hydraulic circuit. The hydraulic circuit discharges a hydraulic oil tank for storing hydraulic oil and a hydraulic oil pre-accumulated. A first supply position for supplying the hydraulic oil of the first flow rate to the head chamber, and the first head side supply flow, which are arranged in the first head side supply flow path from the accumulator to the head chamber. The throttle valve that can be switched to the first blockage position that blocks the path, and the hydraulic oil having a second flow rate that is larger than the first flow rate and is arranged in the supply flow path on the second head side from the accumulator to the head chamber. It is arranged in a check valve that can be switched to a second supply position for supplying to the head chamber and a second blockage position for blocking the supply flow path on the second head side, and a return flow path from the rod chamber to the hydraulic oil tank. A servo valve whose opening can be adjusted between an allowable position where the return flow path is opened to allow the plunger to move forward and a braking position where the return flow path is blocked to brake the advance of the plunger. The control device pressurizes the rod chamber by setting the throttle valve to the first supply position, the check valve to the second closing position, and the servo valve to the braking position. After the rod chamber reaches a predetermined pressure by the treatment and the pressurization treatment, the check valve is set to the second supply position and the opening degree of the servo valve is set to the first opening degree to make the plunger. It is characterized by executing an injection forward process for advancing.

According to the present invention, it is possible to prevent the plunger from suddenly popping out in the injection forward processing.

It is a side view of the die casting machine which concerns on this embodiment. It is a circuit diagram of a hydraulic circuit. It is a hardware configuration diagram of a die casting machine. It is a flowchart of an injection control process. It is a figure which shows the state of the hydraulic circuit in a pressurizing process. It is a figure which shows the state of the hydraulic circuit in the injection advance processing. It is a figure which shows the state of the hydraulic circuit in the protrusion process. It is a figure which shows the state of the hydraulic circuit in the injection retreat processing.

FIG. 1 is a side view of the die casting machine 10 according to the present embodiment. The die casting machine 10 injects molten metal into a mold to manufacture a molded product. As shown in FIG. 1, the die casting machine 10 mainly includes a mold clamping device 20 and an injection device 30.

The mold clamping device 20 opens and closes the mold 21 and clamps the mold. Specifically, the mold clamping device 20 mainly includes a fixed die plate 23 that supports the fixed side mold 22 and a movable die plate 25 that supports the movable side mold 24. The fixed-side mold 22 and the movable-side mold 24 are supported so as to face each other in the left-right direction (horizontal direction) of the die casting machine 10.

The movable die plate 25 moves in the left-right direction along the tie bar 28 by transmitting the driving force of the mold opening / closing cylinder 26 through the toggle link mechanism 27. When the movable die plate 25 moves to the left, the fixed-side mold 22 and the movable-side mold 24 are separated (mold open). On the other hand, when the movable die plate 25 moves to the right, the fixed-side mold 22 and the movable-side mold 24 come into contact with each other (mold closing). Then, when a pressure in the direction of moving the movable die plate 25 to the right is further applied, the fixed-side mold 22 and the movable-side mold 24 are molded.

The injection device 30 injects molten metal into the molded mold 21. The injection device 30 mainly includes an injection sleeve (sleeve) 31, a plunger 32, a hydraulic cylinder 33, and a hydraulic circuit 40. The injection device 30 according to the present embodiment is arranged so as to be separated from the mold clamping device 20 in the horizontal direction (to the right of the mold clamping device 20).

The injection sleeve 31 is a cylindrical member attached to the fixed die plate 23. The tip of the injection sleeve 31 communicates with the internal space (hereinafter, referred to as “cavity”) of the molded mold 21. Further, the molten metal supplied by the ruddle (not shown) is stored in the injection sleeve 31.

The plunger 32 is housed in the injection sleeve 31 so as to be able to move forward and backward. When the plunger 32 advances, the molten metal stored in the injection sleeve 31 is supplied to the cavity. On the other hand, when the plunger 32 retracts, a space for storing the molten metal supplied from the ruddle is formed in the injection sleeve 31.

The hydraulic cylinder 33 advances and retreats the plunger 32 by expanding and contracting with the hydraulic oil supplied and discharged (hereinafter referred to as "supply / discharge"). The supply and discharge of hydraulic oil to the hydraulic cylinder 33 is performed by the hydraulic circuit 40. As shown in FIG. 2, the hydraulic cylinder 33 includes a cylinder tube 34, a piston 35, and a rod 36.

The piston 35 is configured to be movable in the cylinder tube 34. Further, the piston 35 divides the inside of the cylinder tube 34 into a head chamber 37 and a rod chamber 38. The base end of the rod 36 is connected to the piston 35, protrudes to the outside of the cylinder tube 34, and the plunger 32 is connected to the tip end.

When the hydraulic oil is supplied to the head chamber 37 and the hydraulic oil is discharged from the rod chamber 38, the piston 35 moves to the rod chamber 38 side and the rod 36 extends. As a result, the plunger 32 advances in the injection sleeve 31. On the other hand, when the hydraulic oil is supplied to the rod chamber 38 and the hydraulic oil is discharged from the head chamber 37, the piston 35 moves to the head chamber 37 side and the rod 36 shrinks. As a result, the plunger 32 retracts in the injection sleeve 31.

Further, as shown in FIG. 2, the position of the rod 36 is detected by the position sensor 39. The position sensor 39 detects the position of the rod 36 and outputs a position signal indicating the detection result to the control device 60 described later. The position sensor 39 is, for example, a linear encoder.

FIG. 2 is a circuit diagram of the hydraulic circuit 40. As shown in FIG. 2, the hydraulic circuit 40 includes a hydraulic oil tank 41, a motor 42, a hydraulic pump 43, an accumulator 44, a charge valve 45, an electromagnetic proportional throttle valve (throttle valve) 46, and a check valve. It mainly includes 47, 51, a check valve 48, a direction switching valve 49, on-off valves 50, 53, filters 52, 54c, and a servo valve 54.

The hydraulic pump 43 and the accumulator 44 are connected by _a charge flow path L1. The accumulator 44 and the head chamber 37 of the hydraulic cylinder 33 have a first head side supply flow path L ₂ branched from the charge flow path L ₁ and a second head side supply further branched from the first head side supply flow path L ₂ . It is connected to the flow path _L3 . The head chamber 37 of the hydraulic cylinder 33 and the hydraulic oil tank 41 are connected by a head _- side return flow path L4. The hydraulic pump 43 and the rod chamber 38 of the hydraulic cylinder 33 are connected by a rod _- side supply flow path _L5 branched from the charge flow path L1. The rod chamber 38 of the hydraulic cylinder 33 and the hydraulic oil tank 41 are connected by a rod-side return flow path L ₆ branched from the rod-side supply flow path L ₅ .

The hydraulic oil tank 41 stores hydraulic oil. The motor 42 generates a driving force for driving the hydraulic pump 43. _The hydraulic pump 43 transmits the driving force of the motor 42 to pump the hydraulic oil stored in the hydraulic oil tank 41 to the charge flow path L1.

The accumulator 44 stores (accumulates) the hydraulic oil in a compressed state, and supplies the compressed hydraulic oil. More specifically, the accumulator 44 is accumulating hydraulic oil supplied from the hydraulic pump 43 through the charge flow path _L1 . Further, the hydraulic oil discharged from the accumulator 44 is supplied to the head chamber 37 through the first head side supply flow path L ₂ and the second head side supply flow path L ₃ , and is supplied to the head chamber 37 through the second pilot flow path L ₈ (described later). It is supplied to the second pilot port 55d (described later).

_The charge valve 45 is arranged in the charge flow path L1. More specifically, the charge valve 45 is an accumulator from the branch position of the charge flow path L ₁ with the first head side supply flow path L ₂ on the hydraulic pump 43 side and from the branch position with the rod side supply flow path L ₅ . It is arranged on the 44 side. The charge valve 45 is configured to be switchable between a non-charge position A and a charge position B.

The non-charge position A is _a position where the charge flow path L1 is blocked so that the hydraulic oil supplied from the hydraulic pump 43 cannot be charged to the accumulator 44. The charge position B is _a position where the charge flow path L1 is opened so that the hydraulic oil supplied from the hydraulic pump 43 can be charged (accumulated) to the accumulator 44.

The initial position of the charge valve 45 is the non-charge position A. Further, the charge valve 45 is switched from the non-charge position A to the charge position B by applying a control voltage from the control device 60. Further, the charge valve 45 is switched from the charge position B to the non-charge position A again by stopping the application of the control voltage from the control device 60.

The electromagnetic proportional throttle valve 46 is arranged in the supply flow path L2 on the _first head side. More specifically, the electromagnetic proportional throttle valve 46 is on the head chamber 37 side from the branch point of the first head side supply flow path L ₂ with the second head side supply flow path L ₃ , and on the accumulator 44 side from the check valve 47. Is located in. The electromagnetic proportional throttle valve 46 controls the flow rate of the hydraulic oil flowing through the supply flow path L2 on the _first head side according to the control of the control device 60.

The electromagnetic proportional throttle valve 46 according to the present embodiment is configured to be switchable between a first supply position and a first closed position. The first supply position is a position where the flow rate of the hydraulic oil discharged from the accumulator 44 is limited to the first flow rate and supplied to the head chamber 37. The first blockage position is a position where the supply flow path L ₂ on the first head side is blocked.

The initial position of the electromagnetic proportional throttle valve 46 is the first closed position. Further, the electromagnetic proportional throttle valve 46 can adjust the opening degree between the first closed position and the first supply position by applying a control voltage from the control device 60. Further, the electromagnetic proportional throttle valve 46 is switched to the first closed position again by stopping the application of the control voltage from the control device 60.

The check valve 47 is arranged in the supply flow path L2 on the _first head side. More specifically, the check valve 47 is arranged on the head chamber 37 side of the electromagnetic proportional throttle valve 46. The check valve 47 allows the flow of hydraulic oil from the accumulator 44 to the head chamber 37 and shuts off the flow of hydraulic oil from the head chamber 37 to the accumulator 44.

The check valve 48 is arranged in the supply flow path L3 _on the second head side. More specifically, the check valve 48 is arranged on the head chamber 37 side from the branch point of the second head side supply flow path L ₃ with the first head side supply flow path L ₂ . The check valve 48 mainly includes a spool 55, a poppet 56, and a coil spring (urging member) 57.

The spool 55 is a cylindrical member having an internal space. The spool 55 is formed with an inflow port 55a, an outflow port 55b, a first pilot port 55c, and a second pilot port 55d that allow the internal space of the spool 55 to communicate with the outside (flow path). The inflow port 55a is connected to the accumulator 44 side of the supply flow path L3 _on the second head side. The outflow port 55b is connected to the head chamber ₃₇ of the supply flow path L3 on the second head side. The first pilot port 55c is connected to the first pilot flow path L ₇ branched from the rod side return flow path L ₆ . The second pilot port 55d is connected to the second pilot flow path L ₈ branched from the first head side supply flow path L ₂ .

The poppet 56 is housed in the spool 55. The poppet 56 has a first pressure receiving portion 56a facing the first pilot port 55c and a second pressure receiving portion 56b facing the second pilot port 55d. The first pressure receiving portion 56a is a portion that receives the pressure of the hydraulic oil supplied to the first pilot port _55c through the first pilot flow path L7. The second pressure receiving portion 56b is a portion that receives the pressure of the hydraulic oil supplied to the second pilot port _55d through the second pilot flow path L8. The pressure receiving area of the second pressure receiving portion 56b is set to be larger than that of the first pressure receiving portion 56a.

The poppet 56 is configured to be movable between the second supply position and the second blockage position inside the spool 55. The second supply position communicates the inflow port 55a and the outflow port 55b (that is, opens the supply flow path L3 _on the second head side) and supplies the hydraulic oil discharged from the accumulator 44 to the head chamber 37. The position. When the check valve 48 is in the second supply position, the flow rate of the hydraulic oil supplied from the accumulator 44 to the head chamber 37 is set to a second flow rate higher than the first flow rate. The _second blockage position is a position that blocks between the inflow port 55a and the outflow port 55b to block the supply flow path L3 on the second head side.

The coil spring 57 urges the poppet 56 toward the second closed position. The urging force of the coil spring 57 is F ₀ , the force received by the first pressure receiving portion 56a in the pressurizing process (described later) and the injection forward processing (described later) is F ₁ , and the force received by the second pressure receiving section 56b in the pressurizing process is F ₂ . Then, the relationship of F ₀ <F ₁ , F ₀ + F ₂ > F ₁ is established.

That is, when no pressure is applied to both the first pressure receiving portion 56a and the second pressure receiving portion 56b, the check valve 48 (poppet 56) is located at the second closed position. Further, when pressure is applied to the first pressure receiving portion 56a and no pressure is applied to the second pressure receiving portion 56b, the check valve 48 (poppet 56) moves to the second supply position against the urging force of the coil spring 57. To position. Further, when pressure is applied to both the first pressure receiving portion 56a and the second pressure receiving portion 56b, the check valve 48 (poppet 56) is located at the second closed position.

The directional control valve 49 is arranged _in the second pilot flow path L8. More specifically, the direction switching valve 49 is arranged between the branch position of the second pilot flow path L ₈ with the first head side supply flow path L ₂ and the second pilot port 55d. The directional control valve 49 supplies and discharges hydraulic oil to and from the second pilot port 55d under the control of the control device 60.

The directional control valve 49 has a pair of pilot ports 49a and 49b. The directional control valve 49 is configured so that the control device 60 can switch between the cutoff position C, the supply position D, and the return position E by applying a control voltage to one of the pilot ports 49a and 49b. ..

The cutoff position C is a position that cuts off between the accumulator 44 and the second pilot port 55d. The supply position D is a position where the hydraulic oil discharged from the accumulator 44 is supplied to the second pilot port 55d to pressurize the second pressure receiving portion 56b. The recirculation position E is a position where the hydraulic oil of the second pilot port 55d is recirculated to the hydraulic oil tank 41.

The initial position of the directional control valve 49 is the shutoff position C. Further, the directional control valve 49 is switched from the cutoff position C to the supply position D by applying a control voltage from the control device 60 to the pilot port 49a. Further, the directional control valve 49 is switched from the cutoff position C to the return position E by applying a control voltage from the control device 60 to the pilot port 49b. Further, the directional control valve 49 is switched to the cutoff position C again by stopping the application of the control voltage from the control device 60.

The on-off valve 50 is arranged in the head _- side return flow path L4. More specifically, the on-off valve 50 is arranged between the head chamber 37 and the hydraulic oil tank 41. The on-off valve 50 is configured to be switchable between a closed position F and an open position G. The blocking position F is a position where the head _- side return flow path L4 is blocked. The open position G is a position where the head side return flow path _L4 is opened and the hydraulic oil in the head chamber 37 is returned to the hydraulic oil tank 41.

The initial position of the on-off valve 50 is the closing position F. Further, the on-off valve 50 is switched from the closed position F to the open position G by applying a control voltage from the control device 60. Further, the on-off valve 50 is switched from the open position G to the closed position F again by stopping the application of the control voltage from the control device 60.

The check valve 51 is arranged in the rod side supply flow path _L5 . More specifically, the check valve 51 is arranged on the hydraulic pump 43 side from the branch point between the rod side return flow path L ₆ and the first pilot flow path L ₇ of the rod side supply flow path L ₅ , and is arranged from the filter 52. It is arranged on the rod chamber 38 side. The check valve 51 allows the flow of hydraulic oil from the hydraulic pump 43 to the rod chamber 38, and shuts off the flow of hydraulic oil from the rod chamber 38 to the hydraulic pump 43.

The filter 52 is arranged in the rod side supply flow path _L5 . More specifically, the filter 52 is arranged on the hydraulic pump 43 side of the check valve 47 and on the rod chamber 38 side of the on-off valve 53. The filter 52 removes foreign matter (for example, metal powder) contained in the hydraulic oil by passing the hydraulic oil supplied from the hydraulic pump 43. Further, the filter 52 is configured to be removable (replaceable).

The _on -off valve 53 is arranged in the rod side supply flow path L5. More specifically, the on-off valve 53 is arranged on the hydraulic pump 43 side of the check valve 51 ₍ more specifically, the filter 52) of the rod side supply flow path L5. The on-off valve 53 is configured to be switchable between a closed position H and an open position I.

The closing position H is a position where the rod side supply flow path _L5 is blocked and the supply of hydraulic oil from the hydraulic pump 43 to the rod chamber 38 is stopped. The open position I is a position where the rod side supply flow path _L5 is opened to supply hydraulic oil from the hydraulic pump 43 to the rod chamber 38.

The initial position of the on-off valve 53 is the closing position H. Further, the on-off valve 53 is switched from the closed position H to the open position I by applying a control voltage from the control device 60. Further, the on-off valve 53 is switched from the open position I to the closed position H again by stopping the application of the control voltage from the control device 60.

The servo valve 54 is arranged in the rod _- side return flow path L6. The servo valve 54 is a proportional valve capable of adjusting the spool opening degree (opening degree) between the braking position J, the loop position K, and the allowable position L according to the control of the control device 60. More specifically, the servo valve 54 comprises a pair of pilot ports 54a, 54b. The servo valve 54 is spooled between the braking position J, the loop position K, and the allowable position L by supplying pilot pressure oil from the accumulator (not shown) to any of the pair of pilot ports 54a and 54b. Moves. Further, a filter 54c is arranged in the flow path from the accumulator to the pilot ports 54a and 54b.

The braking position J is a position that shuts off the rod _- side return flow path L6 and prevents the hydraulic oil in the rod chamber 38 from returning to the hydraulic oil tank 41 (in other words, braking the advance of the plunger 32). be. The loop position K is a position where the rod chamber 38 side of the rod side return flow path L ₆ and the hydraulic oil tank 41 side of the rod side return flow path L ₆ are made independent loop flow paths. The permissible position L is a position where the return flow path L ₆ on the rod side is opened to allow the hydraulic oil in the rod chamber 38 to return to the hydraulic oil tank 41 (in other words, to allow the plunger 32 to move forward). be.

The initial position of the servo valve 54 is the braking position J. Further, the servo amplifier (not shown) controls the supply amount of the pilot pressure oil to the pilot ports 50a and 50b according to the command value of the forward speed of the plunger 32 output from the control device 60, from the braking position J. The spool opening is adjusted toward the loop position K or the allowable position L. Further, the servo amplifier detects the actual forward speed of the plunger 32 (hereinafter referred to as “measured value”), and adjusts the spool opening degree so that the measured value approaches the command value.

FIG. 3 is a hardware configuration diagram of the die casting machine 10. The die casting machine 10 includes a control device 60. The control device 60 includes, for example, a CPU (Central Processing Unit) 61 which is a calculation means, a ROM (Read Only Memory) 62 which stores various programs, and a RAM (Random Access Memory) 63 which is a work area of the calculation means. Then, each process described later may be realized by reading and executing the program stored in the ROM 62 by the CPU 61.

However, the specific configuration of the control device 60 is not limited to this, and may be realized by hardware such as an ASIC (Application Specific Integrated Circuit) and an FPGA (Field-Programmable Gate Array).

The control device 60 controls the operation of the entire die casting machine 10. More specifically, the control device 60 acquires a position signal output from the position sensor 39. Further, the control device 60 applies and stops the control voltage to the charge valve 45, the electromagnetic proportional throttle valve 46, the directional switching valve 49, and the on-off valves 50 and 53. Further, the control device 60 controls the forward speed of the plunger 32 by outputting a command value to the servo amplifier of the servo valve 54 (so-called ALL-OUT control).

More specifically, the control device 60 supplies hydraulic oil at a predetermined pressure (flow rate) from the accumulator 44 to the head chamber ₃₇ through the second head side supply flow path L3 by opening the check valve 48. .. Further, the control device ₆₀ adjusts the flow rate of the hydraulic oil flowing back from the rod chamber 38 to the hydraulic oil tank 41 through the rod side return flow path L6 by adjusting the spool opening degree of the servo valve 54.

That is, the control device 60 accelerates the plunger 32 by increasing the spool opening degree of the servo valve 54. On the other hand, the control device 60 decelerates (brakes) the plunger 32 by reducing the spool opening degree of the servo valve 54. Further, the smaller the spool opening degree of the servo valve 54, the larger the deceleration (braking force) of the plunger 32.

Next, the injection control process will be described with reference to FIGS. 4 to 8. FIG. 4 is a flowchart of the injection control process. FIG. 5 is a diagram showing a state of the hydraulic circuit 40 in the pressurizing process. FIG. 6 is a diagram showing a state of the hydraulic circuit 40 in the injection forward processing. FIG. 7 is a diagram showing a state of the hydraulic circuit 40 in the projecting process. FIG. 8 is a diagram showing a state of the hydraulic circuit 40 in the injection retreat process.

The injection control process is a process for continuously molding a plurality of molded products. At the start of the injection control process, the mold 21 is molded, the molten metal is stored in the injection sleeve 31, the hydraulic oil of a predetermined pressure is stored in the accumulator 44, and the charge valve 45 is in the non-charge position A. The electromagnetic proportional throttle valve 46 is in the first closed position, the check valve 48 is in the second closed position, the direction switching valve 49 is in the shutoff position C, the on-off valve 50 is in the closed position F, and the on-off valve 53 is in the closed position H. It is assumed that the servo valve 54 is located at the braking position J.

First, as shown in FIG. 5, the control device 60 sets the charge valve 45 at the non-charge position A, the electromagnetic proportional throttle valve 46 at the first supply position, the direction switching valve 49 at the supply position D, and the on-off valve 50. The closing position F is set, the on-off valve 53 is set to the closing position H, and the servo valve 54 is set to the braking position J (S11). Then, the check valve 48 is switched to the second block position by switching the direction switching valve 49 to the supply position D. The process of step S11 is an example of the pressure process.

As a result, the hydraulic oil of the first flow rate is supplied to the head chamber 37 through the supply flow path L2 on the _first head side, and the piston 35 is pressed toward the rod chamber 38 side. However, since the rod side return flow path _L6 is blocked by the servo valve 54 at the braking position J, the hydraulic oil is not discharged from the rod chamber 38. As a result, the hydraulic oil in the rod chamber 38 is pressurized, and a force for pushing the piston 35 against the head chamber 37 (hereinafter, referred to as “back pressure”) is generated.

Further, the pressure in the rod chamber 38 is applied to the first pilot port _55c through the first pilot flow path L7, and presses the first pressure receiving portion 56a. However, since the pressure is also applied to the second pressure receiving portion 56b, the check valve 48 is maintained at the second closed position.

Next, the control device 60 maintains the state of step S11 until the hydraulic oil in the rod chamber 38 reaches a predetermined pressure (S12: No). The control device 60 may detect the pressure in the rod chamber 38 by a pressure sensor (not shown), or may maintain the state of step S11 until a predetermined time elapses.

Next, the control device 60 sets the charge valve 45 to the non-charge position A as shown in FIG. 6 in response to the hydraulic oil in the rod chamber 38 reaching a predetermined pressure (S12: Yes), and electromagnetically. The proportional throttle valve 46 is set to the first supply position, the direction switching valve 49 is set to the reflux position E, the on-off valve 50 is set to the closing position F, the on-off valve 53 is set to the closing position H, and the spool opening of the servo valve 54 is first opened. Reflux (S13). Then, the check valve 48 is switched to the second supply position by switching the direction switching valve 49 to the reflux position E while the first pressure receiving portion 56a is pressed. The process of step S13 is an example of the injection forward process.

As a result, the hydraulic oil is supplied to the head chamber ₃₇ through the first head side supply flow path L2 and the _second head side supply flow path L3, and the hydraulic oil in the rod chamber 38 operates through the rod side return flow path _L6 . Reflux to the oil tank 41. The flow rate of the hydraulic oil flowing into the head chamber 37 in the injection advance process (first flow rate + second flow rate) is larger than the flow rate of the hydraulic oil flowing into the head chamber 37 in the pressurization process (first flow rate). The control device 60 may set the electromagnetic proportional throttle valve 46 to the first closed position in the injection forward processing.

As a result, the plunger 32 advances at the injection forward speed corresponding to the first opening degree, and the molten metal in the injection sleeve 31 is injected into the cavity. In the injection forward processing, the injection forward speed of the plunger 32 can be switched by adjusting the spool opening degree of the servo valve 54. That is, the injection forward processing may include a low-speed forward processing in which the spool opening is relatively small and a high-speed forward processing in which the spool opening is relatively large.

Next, the control device 60 maintains the state of step S13 until the plunger 32 reaches a predetermined forward position (S14: No) based on the position signal output from the position sensor 39. Then, after the plunger 32 reaches the forward position (S14: Yes), the control device 60 causes the mold clamping device 20 to open the mold 21 and the robot arm holds the molded product held by the movable side mold 24. Have it taken out (not shown).

Further, in the control device 60, in conjunction with the mold opening operation by the mold clamping device 20, as shown in FIG. 7, the charge valve 45 is set to the non-charge position A, the electromagnetic proportional throttle valve 46 is set to the first supply position, and the direction is set. The switching valve 49 is set to the supply position D, the on-off valve 50 is set to the closing position F, the on-off valve 53 is set to the closing position H, and the spool opening of the servo valve 54 is set to the second opening smaller than the first opening (S15). .. The process of step S15 is an example of the projecting process. As a result, the plunger 32 decelerates (brakes) from the injection forward speed to the protrusion speed corresponding to the second opening, is pressed against the biscuit at a low speed, and pulls the biscuit from the fixed side mold 22 in conjunction with the mold opening operation. Stick out.

The biscuit refers to the solidified metal remaining in the space (sluice) between the injection sleeve 31 and the cavity in the mold-opened fixed-side mold 21. Further, the protrusion speed is sufficiently slower than the injection forward speed. Further, during the process of step S15, the hydraulic oil may be supplied from the hydraulic pump 43 through a flow path (not shown) without supplying the hydraulic oil from the accumulator 44.

Next, when the protrusion of the biscuit is completed, the control device 60 sets the charge valve 45 to the non-charge position A, the electromagnetic proportional throttle valve 46 to the first closed position, and supplies the direction switching valve 49, as shown in FIG. The position D is set, the on-off valve 50 is set to the open position G, the on-off valve 53 is set to the open position I, and the servo valve 54 is set to the braking position J (S16). The process of step S16 is an example of the injection retreat process. As a result, the hydraulic oil is supplied from the hydraulic pump 43 to the rod chamber 38 through the rod side supply flow path _L5 , and the hydraulic oil is refluxed from the head chamber 37 to the hydraulic oil tank 41 through the head side return flow path _L4 . As a result, the plunger 32 retreats.

Next, the control device 60 maintains the state of step S16 until the plunger 32 reaches a predetermined retracted position (S17: No) based on the position signal output from the position sensor 39. Then, at the timing when the plunger 32 reaches the retracted position (S17: Yes), the control device 60 sets the charge valve 45 to the non-charge position A, the electromagnetic proportional throttle valve 46 to the first closed position, and sets the direction switching valve 49. The shutoff position C is set, the on-off valve 50 is set to the closing position F, the on-off valve 53 is set to the closing position H, and the servo valve 54 is set to the braking position J (S18). The process of step S18 is an example of the initialization process for returning the hydraulic circuit 40 to the state at the start of the injection control process.

Although not shown, the control device 60 stores the molten metal in the injection sleeve 31 in parallel with the processes of steps S16 to S18. Further, although not shown, the control device 60 switches the charge valve 45 to the charge position B when the pressure of the hydraulic oil in the accumulator 44 falls below the lower limit value. As _a result, hydraulic oil is supplied from the hydraulic pump 43 to the accumulator 44 through the charge flow path L1. Then, the control device 60 switches the charge valve 45 to the non-charge position A at the timing when the pressure of the hydraulic oil in the accumulator 44 reaches the upper limit value. The process of charging the accumulator 44 with the hydraulic oil is executed in parallel with, for example, opening the mold, taking out the molded product, and replenishing the molten metal.

Next, the control device 60 determines whether or not a predetermined number of molded products have been molded (S19). Then, when it is determined that the predetermined number of molded products has not been molded yet (S19: No), the control device 60 re-executes the processes of steps S11 to S18. On the other hand, when it is determined that a predetermined number of molded products have been molded (S19: Yes), the control device 60 ends the injection control process. That is, the control device 60 repeats the processes of steps S11 to S18 until a predetermined number of molded products are molded.

According to the above embodiment, for example, the following effects are exhibited.

According to the above embodiment, by executing the pressurization process (S11) prior to the injection advance process (S13), the injection advance of the plunger 32 can be started with the back pressure applied to the piston 35. .. As a result, it is possible to prevent the plunger 32 from suddenly popping out in the injection forward processing.

Further, according to the above embodiment, the check valve 48 can be opened by utilizing the pressure generated in the rod side return flow path _L6 in the pressurizing process (S11). As a result, in the conventional hydraulic circuit, the hydraulic parts for opening and closing the check valve 48 can be omitted, so that the injection control process can be realized by the simple hydraulic circuit 40.

The embodiments described above are examples for the purpose of explaining the present invention, and the scope of the present invention is not limited to those embodiments. Those skilled in the art can practice the invention in various other embodiments without departing from the gist of the invention.

10 ... Die casting machine, 20 ... Mold clamping device, 21 ... Mold, 22 ... Fixed side mold, 23 ... Fixed die plate, 24 ... Movable side mold, 25 ... Movable die plate, 26 ... Mold opening / closing cylinder, 27 ... Toggle link mechanism, 28 ... tie bar, 30 ... injection device, 31 ... injection sleeve, 32 ... plunger, 33 ... hydraulic cylinder, 34 ... cylinder tube, 35 ... piston, 36 ... rod, 37 ... head chamber, 38 ... rod chamber, 39 ... Position sensor, 40 ... Hydraulic circuit, 41 ... Hydraulic oil tank, 42 ... Motor, 43 ... Hydraulic pump, 44 ... Accumulator, 45 ... Charge valve, 46 ... Electromagnetic proportional valve, 47, 51 ... Check valve, 48 ... Check valve, 49 ... Direction switching valve, 49a, 49b, 54a, 54b ... Piston port, 52 ... Filter, 53 ... On-off valve, 54 ... Servo valve, 55 ... Spool, 55a ... Inflow port, 55b ... Outflow port, 55c ... 1st pilot port, 55d ... 2nd pilot port, 56 ... poppet, 56a ... 1st pressure receiving unit, 56b ... 2nd pressure receiving unit, 57 ... coil spring, 60 ... control device, 61 ... CPU, 62 ... ROM, 64 ... notification Device

Claims (4)

A sleeve that communicates with the cavity formed in the mold,
A plunger that supplies the molten metal in the sleeve to the cavity by advancing toward the cavity in the sleeve.
A hydraulic cylinder that advances the plunger by supplying hydraulic oil to the head chamber and retracts the plunger by supplying hydraulic oil to the rod chamber.
A hydraulic circuit that supplies and discharges hydraulic oil to the head chamber and the rod chamber,
A die casting machine provided with a control device for controlling the operation of the hydraulic circuit.
The hydraulic circuit is
A hydraulic oil tank that stores hydraulic oil and
An accumulator that discharges hydraulic oil that has been accumulated in advance,
It is arranged in the first head side supply flow path from the accumulator to the head chamber, and closes the first supply position for supplying the hydraulic oil of the first flow rate to the head chamber and the first head side supply flow path. A throttle valve that can be switched to the first closed position and
A second supply position arranged in the second head side supply flow path from the accumulator to the head chamber to supply hydraulic oil having a second flow rate higher than the first flow rate to the head chamber, and the second head side. A check valve that can be switched to the second blockage position that blocks the supply flow rate,
Arranged in the return flow path from the rod chamber to the hydraulic oil tank, the return flow path is opened to allow the plunger to move forward, and the return flow path is blocked to allow the plunger to move forward. Equipped with a servo valve that can adjust the opening between braking positions for braking
The control device is
Pressurization processing to pressurize the rod chamber by setting the throttle valve to the first supply position, the check valve to the second closing position, and the servo valve to the braking position.
After the rod chamber reaches a predetermined pressure by the pressurizing process, the check valve is set to the second supply position and the opening degree of the servo valve is set to the first opening position to advance the plunger. A die casting machine characterized by performing forward processing. A mold clamping device that opens and closes and clamps the mold,
It comprises the sleeve, the plunger, the hydraulic cylinder, and an injection device having the hydraulic circuit and injecting the weighed molten metal into the cavity of the molded mold.
The control device is
In a state where the mold is molded by the mold clamping device, the pressurizing treatment and the injection advancing treatment are executed.
After executing the injection advance process, with the mold opened by the mold clamping device, the throttle valve is set to the first supply position, the check valve is set to the second closing position, and the servo valve is operated. The die casting machine according to claim 1, wherein the die casting machine is characterized in that a protrusion process for causing the plunger to push out a biscuit from the mold is performed by setting the opening degree to a second opening degree smaller than the first opening degree. The check valve is
An inflow port connected to the accumulator side of the second head side supply flow path, an outflow port connected to the head chamber side of the second head side supply flow path, and a first pilot flow branched from the return flow path. A spool having a first pilot port connected to the road and a second pilot port connected to a second pilot flow path extending from the accumulator.
The second supply position, which is arranged in the spool and communicates the inflow port and the outflow port to supply hydraulic oil to the head chamber, and the inflow port and the outflow port are blocked from each other. A poppet that can move between the second blockage positions that block the supply flow path on the head side, and
The poppet is provided with an urging member for urging the poppet toward the second closed position.
The poppet is
When pressure is applied to the first pilot port and no pressure is applied to the second pilot port, it moves to the second supply position against the urging force of the urging member.
When pressure is applied to the second pilot port, it moves to the second closed position and moves to the second closed position.
The hydraulic circuit is arranged in the second pilot flow path, and the hydraulic oil discharged from the accumulator is supplied to the second pilot port, and the hydraulic oil of the second pilot port is supplied to the hydraulic oil tank. It has a direction switching valve that can be switched to the recirculation position to recirculate to
The control device is
In the pressurization process, the direction switching valve is set to the supply position.
The die casting machine according to claim 1 or 2, wherein in the injection forward processing, the direction switching valve is set to the return position. A sleeve that communicates with the cavity formed in the mold,
A plunger that supplies the molten metal in the sleeve to the cavity by advancing toward the cavity in the sleeve.
A hydraulic cylinder that advances the plunger by supplying hydraulic oil to the head chamber and retracts the plunger by supplying hydraulic oil to the rod chamber.
A die casting machine provided with a hydraulic circuit for supplying and discharging hydraulic oil to the head chamber and the rod chamber.
The hydraulic circuit is
A hydraulic oil tank that stores hydraulic oil and
An accumulator that discharges hydraulic oil that has been accumulated in advance,
It is arranged in the first head side supply flow path from the accumulator to the head chamber, and closes the first supply position for supplying the hydraulic oil of the first flow rate to the head chamber and the first head side supply flow path. A throttle valve that can be switched to the first closed position and
A second supply position arranged in the second head side supply flow path from the accumulator to the head chamber to supply hydraulic oil having a second flow rate higher than the first flow rate to the head chamber, and the second head side. A check valve that can be switched to the second blockage position that blocks the supply flow rate,
Arranged in the return flow path from the rod chamber to the hydraulic oil tank, the return flow path is opened to allow the plunger to move forward, and the return flow path is blocked to allow the plunger to move forward. Equipped with a servo valve that can adjust the opening between braking positions for braking
The check valve is
An inflow port connected to the accumulator side of the second head side supply flow path, an outflow port connected to the head chamber side of the second head side supply flow path, and a first pilot flow branched from the return flow path. A spool having a first pilot port connected to the road and a second pilot port connected to a second pilot flow path extending from the accumulator.
The second supply position, which is arranged in the spool and communicates the inflow port and the outflow port to supply hydraulic oil to the head chamber, and the inflow port and the outflow port are blocked from each other. A poppet that can move between the second blockage positions that block the supply flow path on the head side, and
The poppet is provided with an urging member for urging the poppet toward the second closed position.
The poppet is
When pressure is applied to the first pilot port and no pressure is applied to the second pilot port, it moves to the second supply position against the urging force of the urging member.
When pressure is applied to the second pilot port, it moves to the second closed position and moves to the second closed position.
The hydraulic circuit is arranged in the second pilot flow path, and supplies the hydraulic oil discharged from the accumulator to the second pilot port, and the hydraulic oil in the second pilot flow path is the hydraulic oil. A die casting machine characterized by having a direction switching valve that can be switched to a recirculation position for recirculating to a tank.

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