JP2001314953A - Die casting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die casting apparatus capable of controlling valves and the like of a hydraulic circuit driving a hydraulic cylinder for injection by a simple control unit without cost increase and controlling advancing and retreating speed of a plunger by concise structure. SOLUTION: When molten metal is injected, a flow control valve controlling a flow of working oil discharged from a hydraulic cylinder 22 for injection to a tank 46 is provided with a first oil port A communicating with the side of a piston rod 24 of the hydraulic cylinder 22 for injection, a second oil port B communicating with an opposite side of the piston rod 24 of the hydraulic cylinder 22 for injection, a third oil port P communicating with a hydraulic pump 30, and a fourth oil port T communicating with a tank 46. The flow control valve is constituted with a three position switching valve 74 having a spool 741 in witch the first oil port A and the fourth oil port T are only communicated with each other when the plunger 24 is under advanced movement, and in which the first oil port A and third oil port P, and the second oil port B and fourth oil port T are respectively communicated when the plunger 24 is under retreated movement. The flow control valve is characterized in that the speed of the plunger 24 can be changeable by means of advanced and retreated movement of the hydraulic cylinder 22 for injection and also a directive to the flow control valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die casting apparatus for injecting a molten metal into a cavity defined by a pair of die casting dies to obtain a die cast product.

[0002]

2. Description of the Related Art As an apparatus for injecting a molten metal into a cavity defined by a pair of die-casting dies to obtain a die-cast product, a die-casting apparatus 10 as shown in FIG. 3 is known. The die casting apparatus 10 includes a sleeve 18 for injecting a molten metal 16 into a cavity 14 defined by a pair of die casting molds 12, 12, and is driven by an injection hydraulic cylinder 22 in the sleeve 18. Plunger 20 is slidably provided.

The injection hydraulic cylinder 22 is provided with a plunger 20.
Piston 26 connected to piston 26 via piston rod 24
When hydraulic oil is supplied from the hydraulic oil supply line 40 of the hydraulic circuit 28 shown in FIG. 4 into the hydraulic cylinder 22 for injection on the cylinder head side of the piston 26, that is, on the side opposite to the piston rod 24. The plunger 20 moves forward, whereby the molten metal 16 is injected from the inside of the sleeve 18.

[0004] The hydraulic circuit 28 has a hydraulic pump 30. The hydraulic oil discharged from the hydraulic pump 30 is supplied to an accumulator 38 as a hydraulic oil for operating the hydraulic cylinder 22 for injection, a solenoid valve 32, and a hydraulic oil supply line. 34 and a check valve 36.

The accumulator 38 is in communication with the head side of the injection hydraulic cylinder 22, that is, on the side opposite to the piston rod 24 via a hydraulic oil supply pipe 40. The hydraulic oil supply line 40 is provided with a logic valve 42 that is opened and closed by an electromagnetic pilot valve 44. When the electromagnetic pilot valve 44 is switched to the left position, the logic valve 42 communicates with the pilot chamber of the logic valve 42. Solenoid valve 4
The A port 4 communicates with the tank 46, whereby the valve element of the logic valve 42 is moved in the opening direction by the pressure of the hydraulic oil stored in the accumulator 38, so that the hydraulic oil stored in the accumulator 38 operates. Oil supply line 4
0, and flows into the head side of the hydraulic cylinder 22 for injection.

The hydraulic circuit 28 has a flow control unit 48 for controlling the flow rate of the hydraulic oil discharged from the injection hydraulic cylinder 22 to the tank 46 when the molten metal is injected. The flow control unit 48 has a flow control valve 50. When the flow control valve 50 is switched from the position shown in the figure to the position on the right side in the figure, the hydraulic fluid is injected by the plunger 20 into the hydraulic cylinder for injection. 22 flows out from the piston rod side and passes through the flow control valve 50 and the hydraulic oil discharge line 52 to the tank 4.
6 to be discharged. Further, the flow controller 48 controls the pilot servo valve 5 that operates the flow control valve 50.
The pilot servo valve 54 is supplied with pressure oil from the hydraulic pump 30 from a pilot pressure supply line 56 as pilot pressure.

The pilot pressure supply line 56 branches off from the hydraulic oil supply line 34 between the solenoid valve 32 and the check valve 36. The pilot pressure supply line 56 includes the electromagnetic pilot valve 44 described above. A hydraulic oil supply line 60, which is connected via a branch line 58 and supplies hydraulic oil to the piston rod side of the hydraulic cylinder for injection 22, is connected via a logic valve 62, an electromagnetic switching valve 64 and a branch line 66. Connected.

The electromagnetic pilot valve 44 is configured to operate according to a control signal from a control device (not shown).
Is switched to the position shown, the accumulator 38
At the same time, the supply of the pressurized oil to the injection hydraulic cylinder 22 is shut off, and at the same time, the B port of the electromagnetic pilot valve 44 that is in communication with the pilot chamber of the logic valve 62 communicates with the tank 46. At this time, when the electromagnetic switching valve 64 is switched to the position shown in the figure by a signal from the control device, the A port of the electromagnetic switching valve 64 communicates with the tank 46 and the B port of the electromagnetic switching valve 64 is connected to the branch line 66 at the same time. Communicate. As a result, the pressure oil from the hydraulic pump 30 passes through the electromagnetic valve 32, the hydraulic oil supply line 34, the pilot pressure supply line 56, the branch line 66, the electromagnetic switching valve 64, the logic valve 62, and the hydraulic oil supply line 60. Is supplied to the piston rod side of the hydraulic cylinder for injection 22, the plunger 20 moves backward, and the hydraulic oil on the head side of the hydraulic cylinder for injection 22 flows through the hydraulic oil discharge line 68 and the electromagnetic switching valve 64 to the tank 46.
Is discharged to

[0009]

In such a die-casting apparatus, hydraulic oil is supplied to the piston rod side of the hydraulic cylinder for injection 22 and the hydraulic oil supplied to the head side of the hydraulic cylinder for injection 22 is discharged. By discharging the plunger 20 through the pipe 68 and the electromagnetic switching valve 64 to the tank 46, the plunger 20 which has advanced to a predetermined position can be retracted to the original position. However, plunger 20
Is retracted, the electromagnetic pilot valve 4 described above is used.
4. Since the flow control valve 50 and the electromagnetic switching valve 64 must be switched by a control device (not shown), the configuration of the control device is complicated.

In order to solve such a problem, the above-mentioned flow control valve 50 is constituted by a three-position switching valve 70 as shown in FIG. 5, and this three-position switching valve 70 is switched by a pilot servo valve 54. There has been proposed one that controls the plunger 20 to retreat. According to such a die casting apparatus, since the logic valve 62 and the electromagnetic switching valve 64 are not required unlike the die casting apparatus shown in FIG. 4, the control device for controlling the valves of the hydraulic circuit 28 has a simple configuration. It is possible to

[0011] However, in the conventional die casting apparatus shown in FIG.
Since the pilot check valve 72 must be provided in the hydraulic oil discharge line 68 in order to prevent the oil from flowing to the position switching valve 70, there is a problem that the cost of the hydraulic circuit for driving the injection hydraulic cylinder is increased. 4 and 5, the flow control valves 50, 7 during the retreat operation.
The flow rate of 0 was not controlled.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to control valves of a hydraulic circuit for driving an injection hydraulic cylinder with a relatively simple structure without increasing the cost. An object of the present invention is to provide a die casting device that can be controlled by a device and that can control a forward and backward speed of a plunger with a simple configuration.

[0013]

In order to solve the above-mentioned problems, the present invention provides a sleeve for injecting molten metal into a cavity defined by a pair of die-casting dies, and a sleeve which slides in the sleeve. A plunger freely provided, an injection hydraulic cylinder having a piston connected to the plunger via a piston rod, an accumulator for accumulating a working fluid for operating the injection hydraulic cylinder, and injection of the molten metal And a flow control valve for controlling the flow rate of the working fluid discharged from the injection fluid pressure cylinder to the tank, wherein the flow control valve is connected to the piston rod side of the injection fluid pressure cylinder. A first oil port, a second oil port communicating with a side opposite to a piston rod of the injection fluid pressure cylinder, and the accumulator. A third oil passage communicating with a fluid pressure pump for supplying a working fluid to the accumulator, and a fourth oil passage communicating with the tank, and the first oil passage when the plunger advances. A spool that allows only the fourth oil port to communicate with the first oil port and the third oil port and the second oil port and the fourth oil port when the plunger is retracted; A three-position switching valve is used, and the speed of the plunger is made variable by a command to the flow control valve together with the forward / backward movement of the injection fluid pressure cylinder.

In the die casting apparatus according to the present invention, the three-position switching valve is preferably a closed center type three-position switching valve.

[0015]

FIG. 1 is a block diagram showing an embodiment of the present invention.
A description will be given based on FIG. Note that the same or corresponding portions as those shown in FIGS. 3 to 5 are denoted by the same reference numerals, and detailed description thereof will be omitted for convenience.

FIG. 1 is a diagram showing a schematic configuration of a hydraulic circuit for driving an injection hydraulic cylinder of a die casting apparatus according to a first embodiment of the present invention. In the figure, a die-casting apparatus according to one embodiment of the present invention is a closed center type three-position switching as a flow control valve for controlling a flow rate of hydraulic oil discharged from an injection hydraulic cylinder 22 to a tank 46 during injection of molten metal. It is provided with a valve 74.

The three-position switching valve 74 has four oil ports A, B,
T, P, the first oil passage A is on the piston rod 24 side of the injection hydraulic cylinder 22, and the second oil passage B is connected to the injection hydraulic cylinder 22 via the hydraulic oil discharge line 68. On the side opposite to the piston rod 24, that is, on the cylinder head side,
The third oil passage P is connected to the discharge port of the hydraulic pump 30 via the pilot pressure supply line 56, the hydraulic oil supply line 34 and the solenoid valve 32, and the fourth oil passage T is connected to the hydraulic oil discharge line 52. And communicate with the tanks 46 respectively.

The three-position switching valve 74 is provided with a spool 74 for selectively communicating the first to fourth oil ports A, B, P, and T.
1, and the spool 741 is configured to slide by the pilot pressure from the pilot servo valve 54. Further, the three-position switching valve 74 has a position detector 742 for detecting the position of the spool 741. The signal output from the position detector 742 is subjected to signal processing by a control device (not shown), and then the three-position switching valve 74 is switched. The signal is fed back to the pilot servo valve 54 as a signal indicating the opening degree of the valve 74 (movement amount of the spool 741). The opening of the three-position switching valve 74 is determined by a pressure detector 76 for detecting the pressure on the cylinder head side of the injection hydraulic cylinder 22, a pressure detector 78 for detecting a pressure on the piston rod side of the injection hydraulic cylinder 22, a plunger. 20
Is controlled on the basis of a signal from a position detector 80 for detecting the position.

In such a configuration, when the pilot servo valve 54 is switched from the position shown in FIG. 1 (neutral position) to the position on the right side in FIG. 1 by a signal from a control device (not shown), the pilot pressure from the pilot servo valve 54 is changed. As a result, the spool 741 of the three-position switching valve 74 slides rightward in the drawing, and only the first oil port A and the fourth oil port T communicate with each other.

At this time, when the plunger 20 moves forward with the hydraulic oil supplied from the accumulator 38 to the cylinder head side of the hydraulic cylinder for injection 22, the hydraulic oil is moved along with the forward movement of the plunger 20.
2 is discharged from the piston rod side and discharged from the piston rod side of the injection hydraulic cylinder 22 to the tank 46 through the first oil passage A and the fourth oil passage T of the three-position switching valve 74. Is discharged.

On the other hand, when the pilot servo valve 54 is switched from the position shown in FIG. 1 to the left position in FIG. 1 by a signal from the control device, the spool 741 of the three-position switching valve 74 is rotated by the pilot pressure from the pilot servo valve 54. Sliding to the left in the figure, the first oil port A and the third oil port P
And the second oil passage B and the fourth oil passage T communicate with each other.

At this time, the pressure oil discharged from the hydraulic pump 30 flows into the third oil passage P of the three-position switching valve 74 via the solenoid valve 32, the hydraulic oil supply line 34, and the pilot pressure supply line 56. The hydraulic fluid is supplied from the first oil passage A to the piston rod side of the hydraulic cylinder 22 for injection as hydraulic oil for causing the plunger 20 to move backward. At this time, hydraulic oil is discharged from the cylinder head side of the injection hydraulic cylinder 22 with the retreat operation of the plunger 20, and the injection hydraulic cylinder 2
The hydraulic oil discharged from the second cylinder head side is discharged to the tank 46 through the second oil passage B and the fourth oil passage T of the three-position switching valve 74.

As described above, in the die casting apparatus according to the first embodiment of the present invention, when the plunger 20 is moved forward, only the first oil port A and the fourth oil port T of the three-position switching valve 74 communicate. Conversely, when the plunger 20 is moved backward, the first oil port A and the third oil port P and the second oil port B and the fourth oil port T of the three-position switching valve 74 communicate with each other.
Therefore, unlike the conventional example shown in FIG. 5, it is not necessary to provide the pilot type check valve 72 in the hydraulic oil discharge line 68, so that the cost of the valves of the hydraulic circuit for driving the injection hydraulic cylinder 22 is increased. It can be controlled by a relatively simple control device without the need.

In the above-described embodiment, the amount of movement of the spool 741 of the three-position switching valve 74 is
By controlling with the pilot pressure from 4, the forward and backward speeds of the plunger 20 can be controlled with a simple configuration.

In the first embodiment described above, the pressure oil from the hydraulic pump 30 is supplied to the third oil port P of the three-position switching valve 74. However, in the second embodiment shown in FIG. As described above, the configuration may be such that the pressure oil from the accumulator 38 is supplied to the third oil passage P of the three-position switching valve 74 via the branch line 82 branched from the hydraulic oil supply line 40. With this configuration, when the plunger 20 is retracted, the pressure oil from the accumulator 38 flows into the piston rod side of the hydraulic cylinder 22 for injection, so that the plunger 20 can be returned to the original position in a shorter time than in the first embodiment. It can be retracted to the position.

[0026]

As described above, according to the present invention,
A first oil passage for communicating a flow rate control valve for controlling a flow rate of hydraulic oil discharged from the injection hydraulic cylinder to the tank during injection of the molten metal into the injection hydraulic cylinder on the piston rod side, and a side opposite to the piston rod; A second oil port communicating with the hydraulic cylinder for injection, a fourth oil port communicating with the tank, and a third oil port communicating with the accumulator or the hydraulic pump.
A first oil passage and a fourth oil passage when the plunger is moved forward, and a first oil passage and a third oil passage and a second oil passage when the plunger is moved backward. A three-position switching valve having a spool that communicates the opening and the fourth oil passage is configured so that the plunger speed can be changed by a command to the flow control valve together with the forward and backward operation of the injection fluid pressure cylinder. Thus, the valves of the hydraulic circuit for driving the hydraulic cylinder for injection can be controlled by a relatively simple control device without increasing the cost, and the forward and backward speeds of the plunger can be controlled with a simple structure. Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a hydraulic circuit that drives an injection hydraulic cylinder of a die casting apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of a hydraulic circuit that drives an injection hydraulic cylinder of a die casting apparatus according to another embodiment of the present invention.

FIG. 3 is a sectional view showing a configuration of a molten metal injection section of the die casting apparatus.

FIG. 4 is a diagram showing a schematic configuration of a hydraulic circuit that drives an injection hydraulic cylinder of a conventional die casting apparatus.

FIG. 5 is a diagram showing a schematic configuration of another hydraulic circuit that drives an injection hydraulic cylinder of a conventional die casting apparatus.

DESCRIPTION OF SYMBOLS 12 Die-casting mold 14 Cavity 16 Molten metal 18 Sleeve 20 Plunger 22 Hydraulic cylinder for molten metal injection 24 Piston rod 26 Piston 30 Hydraulic pump 38 Accumulator 46 Tank 54 Pilot servo valve 74 3 Position switching valve A 1st oil passage B second oil port T fourth oil port P third oil port 741 spool

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H089 AA34 AA62 BB27 CC01 DA02 DB46 DB49 DB54 DB63 DB75 EE22 EE24 GG02 JJ04 4F206 AR14 JA07 JD04 JM04 JT02 JT24

Claims (2)

[Claims] 1. A sleeve for injecting molten metal into a cavity defined by a pair of die casting dies, a plunger slidably provided in the sleeve, and connected to the plunger via a piston rod. Fluid cylinder for injection having a set piston, an accumulator for accumulating a working fluid for operating the fluid cylinder for injection, and a flow rate of a working fluid discharged from the fluid cylinder for injection to a tank during injection of the molten metal. A flow control valve for controlling the flow rate control valve, the flow control valve, a first oil passage communicating with the piston rod side of the injection fluid pressure cylinder, and the piston rod of the injection fluid pressure cylinder A second oil port communicating with the opposite side, and a fluid pressure port for supplying a working fluid to the accumulator or the accumulator; And a fourth oil port communicating with the tank, and a fourth oil port communicating with the tank. When the plunger advances, only the first oil port and the fourth oil port communicate with each other. When the plunger is retracted, the injection fluid pressure cylinder comprises a three-position switching valve having a spool for communicating the first oil port and the third oil port and the second oil port and the fourth oil port. A speed of the plunger is made variable by a command to the flow control valve together with the forward and backward movement of the die casting apparatus. 2. The die casting apparatus according to claim 1, wherein the three-position switching valve is a closed center type three-position switching valve.