JPH09216022A - Oil-hydraulic circuit of hydraulic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate switching time between a high and low pressure lines and to improve a hit rate by making accumulators in two pressure circuits into a pressure sealing type. SOLUTION: The accumulators 45, 47 for high and low pressures are provided branching in a pipe line 37 on the delivery side of a variable delivery hydraulic pump 35 which provided in an oil-hydraulic circuit 27 for driving a hydraulic cylinder 17 through a solenoid switching valve 49 and a shut off valve 75 is provided on the return pipe line 61 of the solenoid switching valve 49 to a tank 29. And, pressurized oil in the accumulator 45 for high pressure or the accumulator 47 for low pressure is sealed with the shut off valve 75, so the switching time between the high and low pressure lines is eliminated and the hit rate is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit for a hydraulic cylinder, and more particularly to a hydraulic circuit for a hydraulic cylinder, which is an improved two-pressure hydraulic circuit for driving the hydraulic cylinder.

[0002]

2. Description of the Related Art Conventionally, for example, two accumulators (for high pressure and low pressure) are used as a two-pressure hydraulic circuit for driving a hydraulic cylinder for driving punches provided in a turret punch press, and they are switched as needed. The switching valve is used properly.

A hydraulic circuit shown in FIG. 4, for example, is known as a two-pressure hydraulic circuit for driving the hydraulic cylinder.

That is, the hydraulic circuit 101 includes the tank 10
3, a variable displacement hydraulic pump 109 driven by a pump motor 107 via a filter 105 is provided, and the discharge side pipe line 111 of the variable displacement hydraulic pump 109 is
It communicates with the P port of the 3-position electromagnetic switching valve 117 via the check valve 113 and the filter 115. In addition, the high pressure accumulator 11 is branched in the middle of the discharge side pipeline 111.
9, an electromagnetic switching valve 123 for switching between the low pressure accumulator 121 and the low pressure accumulator 121 is provided.

When the flow paths of the three-position electromagnetic switching valve 117 are switched to connect the P port and the A port and the B port and the T port, the pressure oil passes through the pipe 125 and the hydraulic cylinder 127.
To the upper oil chamber 129, and the piston rod 131 is lowered. Then, the lower oil chamber 133 of the hydraulic cylinder 127
The pressure oil discharged further enters the B port of the three-position electromagnetic switching valve 117 through the pipe 135 and returns from the T port to the return pipe 1
The pressure oil is returned to the tank 103 through 37. Further, a pulsation prevention damper 1 for preventing pulsation is provided in the middle of the return pipe 137.
39 is provided. Reference numeral 141 is a stop valve, reference numeral 143 is a check valve operated by pilot pressure, and a cooler 145 is provided at the end of the return line 137.

Next, when the ports of the 3-position solenoid operated directional control valve 117 are switched so that the P port and the B port and the A port and the T port are communicated with each other, the pressure oil supplied from the discharge side conduit 111 is changed to the P port. Then, the oil is supplied to the lower oil chamber 133 provided in the hydraulic cylinder 127 through the pipe line 135 through the B port.

The piston rod 131, to which the pressure oil is supplied to the lower oil chamber 133, rises, and the oil in the upper oil chamber 129 passes through the pipe line 125 and from the A port through the T port to the return pipe line 1.
It is returned to the tank 103 through 37.

With the above structure, the three-position electromagnetic switching valve 117
The piston rod 131 provided on the hydraulic cylinder 127 can be moved up and down by switching the ports of the above, and the desired punching can be performed on the work by the movement of the piston rod 131.

Next, in order to set the line to the high pressure line or the low pressure line, the electromagnetic switching valve 123 is operated to connect the P port and the A port and the B port and the T port. Then, the pressure oil flowing in from the discharge side pipe line 111 passes through the branched pipe line 147 and communicates with the low pressure accumulator 121 from the P port through the A port, and the line pressure is set to a low pressure. On the other hand, the high pressure accumulator 119
The pressure oil in the inside is returned from the B port to the tank 103 via the T port, the pipe line 149 and the return pipe line 137.

When the electromagnetic switching valve 123 is operated to connect the P port and the B port and the A port and the T port, the pressure oil flowing from the discharge side pipe line 111 passes through the branched pipe line 147. The line pressure is set to a high pressure by communicating with the high pressure accumulator 119 from the P port through the B port. Then, the pressure oil in the low-pressure accumulator 121 is returned from the A port to the T port through the pipe line 149 and the return pipe line 137 to the tank 103. The configuration of the hydraulic circuit 101 as described above is generally adopted.

[0011]

By the way, in the two-pressure hydraulic circuit 101 for driving the above-mentioned conventional hydraulic cylinder 127, the high pressure line and the low pressure line are connected to the electromagnetic switching valve 123.
At the time of switching, the high or low pressure accumulator 119 or 121 which is not used is a circuit for discharging the oil in the accumulator to the tank 103.

Therefore, even if the low pressure line is switched to the high pressure line, it takes a long time to accumulate the pressure in the high pressure accumulator 119, and the punching process cannot be started immediately.

An object of the present invention is to provide a hydraulic circuit for a hydraulic cylinder in which the accumulator in the two pressure circuits is a pressure-sealed type, thereby eliminating the switching time between the high pressure line and the low pressure line and improving the hit rate. is there.

[0014]

To achieve the above object, the hydraulic circuit of the hydraulic cylinder of the present invention according to claim 1 is a two-pressure hydraulic circuit for driving the hydraulic cylinder, and is provided in the two-pressure hydraulic circuit. It is characterized in that a high pressure accumulator and a low pressure accumulator are provided by branching to a discharge side pipe line of a hydraulic pump via an electromagnetic switching valve, and a shutoff valve is provided in a return line to the tank by the electromagnetic switching valve. It is a thing.

The hydraulic circuit of the hydraulic cylinder of the present invention according to claim 2 is characterized in that the hydraulic cylinder is a drive device for reciprocating the punch of the punch press.

By using the hydraulic circuit of the hydraulic cylinder according to the above-mentioned claims 1 and 2, a shutoff valve is provided in the return line of the electromagnetic switching valve for switching between the high pressure line and the low pressure line, and the accumulator is opened and closed by opening and closing the shutoff valve. It can be pressure-filled type, which eliminates the switching time between high and low pressure and improves the hit rate.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Although the present embodiment is directed to a turret punch press as an example, the present invention is not limited to this model.

First, in order to facilitate understanding, the turret punch press will be briefly described.

Referring to FIG. 3, the turret punch press 1 is provided with a gate-shaped frame 3, which is a lower base 5, a side frame 7 standing on the lower base 5, and this side frame. 7 and an upper frame 9 provided on the upper part of the frame 7.

A rotatable lower turret 11 is supported on the lower base 5, and a plurality of dies D are mounted on the circumference of the lower turret 11 at appropriate intervals. A rotatable upper turret 13 is supported on the upper frame 9 corresponding to the lower turret 11, and a plurality of punches P are mounted on the upper turret 13 at a position corresponding to the die D.

FIG. 3 of the lower and upper turrets 11 and 13.
, The position of the die D and the punch P mounted on the right side is the processing position.
A striker 15 is provided on the upper frame 9 above and below so as to be vertically movable. The striker 15 is connected to a hydraulic cylinder 17 as a drive device provided in the upper frame 9 via a ram 19, for example.

At the right end in FIG. 3 on the lower base 5, there is provided a carriage base 21 which is movable in the Y-axis direction (left and right direction in FIG. 3). This carriage base 21 is in the X-axis direction. A carriage 23 that is movable in the direction (perpendicular to the paper surface in FIG. 3) is provided. The carriage 23 is provided with a plurality of work clamps 25 that clamp the work W at appropriate intervals in the X-axis direction.

With the above construction, by moving the carriage base 21 in the Y-axis direction and the carriage 23 in the X-axis direction, the work W clamped by the work clamp 25 provided on the carriage 23 is moved in the X-axis and Y-axis directions. The workpiece W is moved in the direction, and the desired position of the work W is positioned at the processing position.

With the desired position of the work W positioned at this machining position, the upper and lower turrets 13, 11 are placed.
Is rotated to index and position the desired punch P and die D at the processing position. Next, by driving the hydraulic cylinder 17 to move the striker 15 up and down via the ram 19, normal punching is performed at a desired position of the work W by cooperation of the punch P and the die D. .

Next, the hydraulic circuit 27 for supplying pressure oil to the hydraulic cylinder 17, which is the main part of the embodiment of the present invention, will be described in detail. Since each device provided in the hydraulic circuit 27 is already known, the description of its structure will be omitted.

Referring to FIG. 1, the hydraulic circuit 27 is provided with a variable displacement hydraulic pump 35 driven by a pump motor 33 from a tank 29 through a filter 31. The discharge of the variable displacement hydraulic pump 35 is provided. The side conduit 37 communicates with the P port of the three-position electromagnetic switching valve 43 via the check valve 39 and the filter 41. An electromagnetic switching valve 49 that branches to switch between the high pressure accumulator 45 and the low pressure accumulator 47 is provided in the middle of the discharge side conduit 37.

When the flow path of the 3-position solenoid operated directional control valve 43 is switched to connect the P port and the A port, and the B port and the T port, the pressure oil flows into the upper oil chamber 53 of the hydraulic cylinder 17 through the pipe line 51. Then, the piston rod 55 is lowered. Then, the pressure oil discharged from the lower oil chamber 57 of the hydraulic cylinder 17 enters the B port of the three-position electromagnetic switching valve 43 through the conduit 59, the T port through the return conduit 61, and the tank 29.
The pressure oil is returned to. Further, a pulsation prevention damper 63 for preventing pulsation is provided in the middle of the return pipe 61. Reference numeral 65 is a stop valve, reference numeral 67 is a check valve operated by pilot pressure, and a cooler 69 is provided at the end of the return conduit 61.

Next, when the ports of the 3-position solenoid operated directional control valve 43 are switched so that the P port and the B port and the A port and the T port are communicated with each other, the pressure oil supplied from the discharge side conduit 37 is the P port. Further, it is supplied to the lower oil chamber 57 provided in the hydraulic cylinder 17 through the line 59 via the B port.

When pressure oil is supplied to the lower oil chamber 57, the piston rod 55 rises, and the oil in the upper oil chamber 53 is transferred to the pipeline 51.
Through the return port 61 from the A port to the T port and returned to the tank 29.

With the above construction, the piston rod 55 provided on the hydraulic cylinder 17 can be moved up and down by switching the port of the 3-position solenoid operated directional control valve 43, and the desired punching process is applied to the work by the movement of the piston rod 55. Can be given.

Next, in order to set the line to the high pressure line or the low pressure line, referring to FIG. 2 together, the electromagnetic switching valve 49 is operated to connect the P port and the A port and the B port and the T port. Excuse me. Then, the discharge side conduit 37
The pressure oil that further flows in communicates with the low pressure accumulator 47 through the branched pipe line 71 through the P port and the A port, and the line pressure is set to a low pressure.

On the other hand, the pressure oil in the high-pressure accumulator 45 is returned from the B port through the T port through the conduit 73, through the shutoff valve 75 and back into the return conduit 61. Since the circuit of the shutoff valve 75 is always closed as shown in FIG. 2, the pressure oil in the high pressure accumulator 45 does not return to the tank 29, and the pressure oil in the high pressure accumulator 45 is It keeps the high pressure.
Reference numeral 77 is a throttle valve.

Further, by operating the electromagnetic switching valve 49,
When the P port and the B port and the A port and the T port are made to communicate with each other, the pressure oil that has flowed in through the discharge side pipeline 37 communicates with the high pressure accumulator 45 through the branched pipeline 71 through the P port through the B port. , The line pressure is immediately set to high pressure. The pressure oil in the low pressure accumulator 47 passes from the A port through the T port through the pipe 73, but is closed by the shutoff valve 75.
The pressure oil in 7 does not return to the tank 29, and the pressure oil in the low pressure accumulator 47 remains at a low pressure.

With the configuration as described above, the electromagnetic switching valve 4
Even if the port 9 is switched, the oil in the high and low pressure accumulators 45 and 47 can be processed without returning to the tank 29. Further, since the shutoff valve 75 is turned on and off in conjunction with the main power source, there is no problem in terms of safety.

Thus, the switching time between the high and low voltage circuits can be shortened and the hit rate can be improved.

The present invention is not limited to the above-described embodiments of the invention, but can be implemented in other modes by making appropriate changes.

[0037]

As will be understood from the above description of the embodiments, the present invention according to claims 1 and 2 provides a high pressure circuit provided with a high pressure accumulator in a two-pressure hydraulic circuit, A shut-off valve was provided in the return line to the tank of the electromagnetic switching valve that switches between the low-voltage circuit equipped with the low-pressure accumulator.

Since the oil in the accumulator can be switched to the high pressure line and the low pressure line with no switching time, the hit rate can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a hydraulic circuit of a hydraulic cylinder showing a main part of the present invention.

FIG. 2 is an enlarged explanatory diagram of a hydraulic circuit of a portion indicated by an arrow II in FIG.

FIG. 3 is a front explanatory view showing a schematic configuration of a hydraulic turret punch press which is an example of an embodiment for carrying out the present invention.

FIG. 4 is an explanatory diagram of a hydraulic circuit of a hydraulic cylinder showing a conventional example.

[Explanation of symbols]

 1 Turret Punch Press 17 Hydraulic Cylinder 27 Hydraulic Circuit 29 Tank 35 Variable Displacement Hydraulic Pump (Hydraulic Pump) 37 Discharge Side Pipe 45 High Pressure Accumulator 47 Low Pressure Accumulator 49 Electromagnetic Switching Valve 61 Return Pipe 75 Shut Off Valve P Punch

Claims (2)

[Claims] 1. A two-pressure hydraulic circuit for driving a hydraulic cylinder is branched into a discharge side pipe line of a hydraulic pump provided in the two-pressure hydraulic circuit, and a high pressure accumulator and a low pressure accumulator are provided via an electromagnetic switching valve. A hydraulic circuit of a hydraulic cylinder, wherein a shutoff valve is provided in a return line to the tank by the electromagnetic switching valve. 2. A hydraulic circuit for a hydraulic cylinder according to claim 1, wherein the hydraulic cylinder is a drive device for reciprocating a punch of a punch press.