JPH094609A - Hydraulic device - Google Patents

Abstract

PURPOSE: To provide a hydraulic device capable of dissolving back pressure and oil hammer occurred at the time when a smaller cylinder of a double cylinder actuates. CONSTITUTION: The piston rod 45 of a double cylinder 19 is lowered or raised by switching a changeover switch 65 and a servo valve 57. The piston rod 45 is raised by switching the changeover switch 65 and sending oil pressure to a lower cylinder 51. Specially, a large quantity of oil contained in an upper cylinder chamber 49 of larger cylinder 19L enters a cylindrical accumulator 85 through a servo valve 47 and is relaxed and dissolved at once by an oil tank and a spring force without causing back pressure or oil hammer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic system, and more particularly, to a hydraulic system in a hydraulic press machine such as a turret punch press, which prevents an oil hammer generated in an oil return circuit. Regarding

[0002]

2. Description of the Related Art Conventionally, a hydraulic device is used in a hydraulic press machine such as a turret punch press. When high-speed oil is returned to the return circuit in the hydraulic circuit of this hydraulic device, the collision of oil and oil causes a metallic noise of an oil hammer. As a means for mitigating this oil hammer, there is one that incorporates a piston type accumulator equipped with a spring as known from Japanese Utility Model Laid-Open No. 2-1188697 in an oil return circuit. It is not a means of easing the hammer. Therefore, as a means for further mitigating the oil hammer, the actual open flat 5-5
A piston-type accumulator equipped with a spring and an accumulator with an oil sump, which are known from Japanese Laid-Open Patent Publication No. 0102, are used in parallel.

[0003]

By the way, in the above-mentioned conventional mitigation means using the piston type accumulator and the accumulator with the oil reservoir in parallel, the return oil once enters the oil reservoir accumulator and then enters the piston type accumulator. Because of the presence of Wang Kyun, the frequency changed, making it unsuitable for large flows.

Particularly, in a double cylinder hydraulic circuit consisting of a small cylinder and a large cylinder, the amount of oil and the amount of stroke of the small cylinder return and the large cylinder return are different, and there is a parameter that determines the back pressure that causes the oil hammer. There are too many accumulators to solve all the problems. Particularly in the case of a small cylinder, the large flow rate changes depending on the stroke amount, and therefore the oil hammer cannot be completely eliminated.

An object of the present invention is to provide a hydraulic system which eliminates back pressure and oil hammer generated when a double cylinder operates.

[0006]

In order to achieve the above object, a hydraulic system of the present invention according to claim 1 is provided with a switching valve and a servo valve in a hydraulic circuit for operating a double cylinder composed of a small cylinder and a large cylinder. A piston type accumulator having a spring installed in the return oil line connecting the switching valve and the tank, and an oil reservoir via a piston in the return line connecting the servo valve and the tank. It is characterized in that it is provided with a cylindrical accumulator equipped with a spring.

According to a second aspect of the present invention, there is provided the hydraulic system according to the first aspect, wherein the double cylinder is a drive device for reciprocating a ram of a press machine. .

[0008]

In the hydraulic system of the present invention according to claims 1 and 2,
When the switching valve is switched and the servo valve is operated for low pressure and high speed to send low pressure oil to the upper cylinder chamber of the small cylinder, the piston rod of the double cylinder is lowered at a high speed due to a low load. Then, when the servo valve is switched to, for example, high pressure and low speed, the piston rod is further lowered at a low speed due to the high load. At that time, the pressure oil contained in the lower cylinder chamber of the double cylinder is returned to the tank without emitting an oil hammer by the piston type accumulator through the switching valve.

Further, when the piston rod of the double cylinder is raised, for example, the switching valve is switched and pressure oil is sent to the lower cylinder chamber, so that the piston rod is raised. At that time, the pressure oil in the upper cylinder chamber of the small cylinder passes through the servo valve and the switching valve, is relaxed by the piston type accumulator, and is returned to the tank without generating an oil hammer.

Further, a large amount of oil in the upper cylinder chamber of the large cylinder enters the cylindrical accumulator through the servo valve, and is alleviated at once by the urging force of the oil sump and the spring, so that the tank does not emit an oil hammer. Returned to.

[0011]

Embodiments of the present invention will be described in detail below with reference to the drawings. First, an outline of, for example, a turret punch press as a press machine to which the hydraulic device of the present invention is applied will be described.

Referring to FIG. 3, the turret punch press 1 includes side frames 5 and 7 which are erected on both sides of a base 3.
The upper frame 9 is supported by a gate-shaped frame. On the lower surface of the upper frame 9, a disc-shaped upper turret 11 having a large number of punches P as upper molds mounted thereon is rotatably mounted by an upper rotary shaft 13. Further, on the upper surface of the base 3, a lower turret 15 on which a plurality of dies D as lower dies facing each punch P are mounted.
Is rotatably mounted by a lower rotary shaft 17.
Further, a ram 21 which is operated by a drive cylinder 19 is provided at a position directly above the punch P in the upper frame 9.

Although not shown in the drawings, the upper turret 11 and the lower turret 15 are rotated in the same direction in synchronization with a servo motor, and the punch P and the die D selected at a position directly below the ram 21 are indexed and driven. The ram 21 is moved up and down by the operation of the cylinder 19, and the punch P and the die D cooperate with each other to punch the work W.

On the other hand, a moving positioning device 23 is provided for moving and positioning the work W in the front-rear direction and the left-right direction. That is, the carriage base 25 of the movement positioning device 23 is integrally attached to the movable table 27 and is movable in the front-rear direction. The carriage base 25 is provided with a carriage 31 provided with a clamp device 29 for gripping the plate W so as to be movable in the left-right direction. A fixed table 33 for movably supporting the plate material W is provided on the upper surface of the base 3.

With the above arrangement, the plate material W on the fixed table 33 and the movable table 27 is gripped by the clamp device 29. Then, by moving the carriage base 25 in the front-rear direction and moving the carriage 31 in the left-right direction, the plate material W can be moved and positioned at predetermined positions in the front-rear direction and the left-right direction.

A hydraulic device 3 including a drive cylinder 19 for operating the turret punch press 1 having the above-described structure.
5 is constituted by the hydraulic circuit 37 shown in FIG. The drive cylinder 19 is a double cylinder, and is composed of a small cylinder 19S and a large cylinder 19L. That is, a small cylinder body 41 is suspended in the upper portion of the cylinder body 39, and a piston rod 45 integrated with the piston 43 is mounted in the cylinder body 39. The ram 21 is integrated with the lower end of the piston rod 45.

With the piston 43 as a boundary, the piston 43
At the upper part of the upper small cylinder chamber 47 and the large upper cylinder chamber 4
9 is formed, and a lower cylinder chamber 51 is formed below the piston 41. A lower end of an oil passage 53 penetrating in the vertical direction of the small cylinder body 41 is communicated with the small upper cylinder chamber 47, and an upper end of the oil passage 53 is connected to one end of a pipe 55. The piping 55 is connected to the A port of the servo valve 57.

In the large upper cylinder chamber 49, an oil passage 59 vertically penetrating the upper wall of the cylinder body 39.
Of the oil passage 59 is connected to one end of the pipe 61. The other end of the pipe 61 is connected to the B port of the servo valve 57. The servo valve 57 has a solenoid SOL1.

One end of a pipe 63 is connected to the lower cylinder chamber 51, and the other end of the pipe 63 is a switching valve 65.
Connected to the B port of the. One end of a pipe 67 is connected to the P port of the servo valve 57 and the pipe 6
The other end of 7 is connected to the A port of the switching valve 65. The switching valve 65 is provided with a solenoid SLO2.

One end of a pipe 69 is connected to the P port of the switching valve 65, and the other end of the pipe 69 is connected to a tank 73 via a filter 71. A pump 77 operated by a motor 75 is provided in the middle of the pipe 69.
Is provided. One end of a pipe 79 is connected to the T port of the switching valve 65, and the tank 73 is connected to the other end of the pipe 79. Moreover, the pipe 7
A piston type accumulator 83 is connected in the middle of 9 through a pipe 81.

One end of the pipe 83 is connected to the T port of the servo valve 57, and the other end of the pipe 83 is connected to the C port of the cylindrical accumulator 85. In addition, this cylindrical accumulator 8
One end of the pipe 87 is connected to the D port of No. 5, and the other end of the pipe 87 is connected in the middle of the pipe 79.

Cylindrical accumulator 85
Is a cylindrical body 89, as shown in FIG.
A piston 91 is mounted in the body 89. A spring 93 biased upward is provided in the lower part of the piston 91, and an oil reservoir 95 filled with oil is provided in the upper part of the piston 91. The oil sump 95 is connected to the other end of the pipe 83 and one end of the pipe 87.

With the above structure, when the motor 75 is driven and the pump 77 is operated, the oil in the tank 73 is discharged to the pipe 69 through the filter 71. This piping 69
The pressure oil discharged to the solenoid SOL2 of the switching valve 65
Is operated to connect the P port and the A port, and the T port and the B port, respectively, to be sent to the pipe 67.

When the solenoid SOL1 of the servo valve 57 is operated to connect the P port and the A port and the T port and the B port, respectively, the pressure oil in the pipe 67 becomes
5, it is sent to the small upper cylinder chamber 47 via the oil passage 53.

The pressure oil sent to the small upper cylinder chamber 47 causes the piston rod 4 integrated with the piston 43.
When 5 descends at a high speed due to a low load and the ram 21 descends, the pressure oil in the lower cylinder chamber 51 is returned to the tank 73 through the pipes 63 and 79, and further through the piston type accumulator 83. At this time, the pressure oil that has entered the piston type accumulator 83 is canceled by the urging force of the spring 83, and can be eliminated without generating back pressure and oil hammer.

When the processing pressure is large, the servo valve 5
When the servo valve SOL1 of No. 7 is switched to operate, the P port communicates with the A and B ports, so that the pressure oil is sent to the small upper cylinder chamber 47 and also to the large upper cylinder chamber 49 via the pipe 61 and the oil passage 59. Since the piston rod 45 integrated with the piston 43 is processed at a low speed by a high load by the pressure oil sent to the small upper cylinder chamber 47 and the large upper cylinder chamber 49, the ram 21 descends.
The punch P further descends, and the work W is punched.

After punching the work W, the changeover valve 65 and the servo valve 57 are changed over so that the P port and the B port of the changeover valve 65 and the T port and the A port are communicated with each other, and the P port of the servo valve 57 is connected. And A port, T port and B port can be connected.

The pressure oil discharged to the pipe 69 is sent to the lower cylinder chamber 51 through the pipe 63, and the piston rod 45 integrated with the piston 43 is lifted. At that time, the pressure oil in the small upper cylinder chamber 47 is transferred to the oil passage 53,
It is returned to the tank 73 through the pipes 55, 67, 79 and the piston type accumulator 83. At this time, in the piston type accumulator 83, the above-described action is performed and the back pressure and the oil hammer can be eliminated without being generated.

On the other hand, the pressure oil in the large upper cylinder chamber 49 is sent to the oil sump 95 from the C port of the cylindrical accumulator 85 through the oil passage 59 and the pipes 61 and 83. The pressure oil that has entered from the C port once enters the oil sump 95, and if the oil that is filled in the oil sump 95 and cannot reach a low pressure is alleviated by the spring force of the spring 93, the pressure becomes even lower. It is returned from the D port to the tank 73 through the pipes 87 and 79. As a result, back pressure and oil hammer can be eliminated without being generated.

The present invention is not limited to the above-described embodiments, but can be carried out in that form by making appropriate changes.

[0031]

As can be understood from the above description of the embodiments, according to the inventions of claims 1 and 2, the return line of the hydraulic circuit using the double cylinder composed of the small cylinder and the large cylinder is provided. Further, by providing the cylindrical accumulator, it is possible to eliminate the back pressure and the oil hammer in the return pipe line when the piston rod is returned to the original position without being generated.

[Brief description of drawings]

FIG. 1 is a diagram showing a hydraulic circuit using a hydraulic device of an embodiment for carrying out the present invention.

FIG. 2 is a configuration diagram of the cylindrical accumulator shown in FIG.

FIG. 3 is a schematic view of a turret punch press to which the hydraulic device of the present invention is applied.

[Explanation of symbols]

 1 Turret punch press 19 Drive cylinder (double cylinder) 19S Small cylinder 19 Large cylinder 21 Ram 35 Hydraulic system 37 Hydraulic circuit 47 Small upper cylinder chamber 49 Large upper cylinder chamber 51 Lower cylinder chamber 57 Servo valve 65 Switching valve 73 Tank 83 Piston Type Accumulator 85 Cylindrical accumulator 93 Spring 95 Oil sump

Claims (2)

[Claims] 1. A piston in which a switching valve and a servo valve are provided in a hydraulic circuit for operating a double cylinder composed of a small cylinder and a large cylinder, and a spring is mounted in the return oil line connecting the switching valve and the tank. A hydraulic system comprising a mold accumulator and a sillindrill cal accumulator equipped with an oil reservoir and a spring via a piston in the middle of a return line connecting the servo valve and the tank. 2. The hydraulic system according to claim 1, wherein the double cylinder is a drive device that reciprocates a ram of a press machine.