JP2000329104A - Hydraulic control method for press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform precisely as well as easily pressure velocity control and positioning control in a press, a rolling field and the like. SOLUTION: A hydraulic pump 6 is drivingly controlled in a manner to be variable in a number of revolutions by a driving motor 8 such as a servo motor. Further, a hydraulic circuit 1 for a press between an output cylinder 4 and the hydraulic pump 6 is provided with a relief valve 7 for allowing the escape of a predetermined flow rate. The number of revolutions of the driving motor 8 such as the servo motor is controlled so as to be variable for driving the hydraulic pump 6 on the basis of a position command or a velocity command of a pressurized body at pressing the output cylinder 4, then the number of revolutions of the driving motor 8 is gradually reduced while oil exceeding the escape amount from the relief valve 7 is supplied, so that the pressurized body is controlled at a predetermined position or a predetermined velocity. As required, the output of the output cylinder 4 is controlled to correct the fall thereof by granting a reacting cylinder 12 which always produces a repulsive force in the output cylinder 4 or an elastic material or accumulated force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a hydraulic pressure for pressing, which can easily and accurately control a rolling speed and a position in a press and rolling field.

[0002]

2. Description of the Related Art Conventionally, in press machines and rolling equipment,
Hydraulic pressure reduction devices are often used, and precision control devices such as servo valves are used to precisely control the reduction speed and position.

[0003]

Therefore, the control equipment is expensive, and high-level cleaning of the hydraulic piping and the like is required. Was very expensive. It is known that a hydraulic pump can be driven forward and reverse to operate a small-capacity actuator. However, in a large-output, high-speed hydraulic press, etc., hydraulic control by a large-capacity pump and a servo valve is required. Was needed.

Further, in the conventional hydraulic circuit for pressing, the hydraulic pump is rotationally driven by a drive motor with the circuit closed, and the rise in pressure is released by a relief valve or the like. And heat is generated also in the hydraulic circuit and the like, causing deterioration of the hydraulic oil and the like.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in order to solve the above-mentioned problems, an output cylinder is driven by a hydraulic pump to press a slide or the like to a predetermined position. A hydraulic pressure control method for pressing down a body, wherein said hydraulic pump is variably driven and controlled by a drive motor such as a servomotor, and a hydraulic circuit for pressing between an output cylinder and a hydraulic pump is provided. A relief valve for releasing a predetermined flow rate is provided, and when the output cylinder is pressed, the rotation speed of a drive motor such as a servo motor that drives a hydraulic pump based on a position command or a speed command of a pressing body is variably controlled to perform the release. It is characterized in that the rotation speed is gradually reduced while supplying the oil amount more than the escape amount from the valve, and the pressing body is position-controlled or speed-controlled to a predetermined position or a predetermined speed. It provides a hydraulic control method of pressure.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The hydraulic control method for pressing according to the present invention is a hydraulic control method for pressing in which a hydraulic pump drives an output cylinder to push a pressing body such as a slide to a predetermined position. A drive valve such as a servomotor for variably controlling the rotational speed of the hydraulic pump, and arranging a relief valve for releasing a predetermined flow rate in a pressing hydraulic circuit between the output cylinder and the hydraulic pump; When pressing, the rotation speed of the drive motor such as the servo motor that drives the hydraulic pump is variably controlled based on the position command or speed command of the pressing body, and gradually rotates while supplying the oil amount more than the escape amount from the relief valve. The number is reduced, and the pressing body is position-controlled or speed-controlled to a predetermined position or a predetermined speed.

The hydraulic circuit 1 for pressing can be used for slide pressurization of a hydraulic press, hydraulic pressure reduction of rolling equipment, and other devices. As shown in FIG. 1, an output cylinder for pressurizing a slide 3 of a hydraulic press 2 is used. 4 is connected to a hydraulic pump 6 via a check valve 5 by piping, and a relief valve 7 for releasing a predetermined flow rate is connected to the pressing hydraulic circuit 1 by piping.

A drive motor 8 such as a servomotor is mounted on the hydraulic pump 6 as shown in FIG. 1, and a predetermined amount of hydraulic pressure and hydraulic pressure can be discharged by variably controlling the rotation speed of the hydraulic pump 6. In this way, the controller 11 compares the feedback signal from the position detector 9 or the speed detector 10 of the slide 3 with the command value set by the program by the controller, and controls the slide 3 to a predetermined position at a predetermined speed. Press molding.

As shown in FIG. 1, a pair of left and right reaction force cylinders 12 are disposed opposite to the slide 3, and a predetermined pressure is applied to the reaction force cylinders 12 by a reaction force generation circuit 14 using an accumulator 13. In this way, the overshoot caused by the position control of the slide 3 can be corrected. 15 is a pressure generating pump, and 16 is a switching valve.

In the above description, the pressing body of the slide 3 is repelled by the hydraulic pressure of the reaction force cylinder 12 and the accumulator 13 for correction. However, the correction may be performed by disposing a spring, a cushion, or the like.

[0011]

FIG. 1 shows an embodiment of the present invention, in which the control of pressing a slide 3 of a hydraulic press is performed. As described above, the output pressure of the hydraulic pump 6 is variably controlled by the drive motor 8 of the servo motor to the output cylinder 4 for pressing the slide 3, and the relief valve 7 for releasing a fixed amount to the pressing hydraulic circuit 1 is connected by piping. It is.

A reaction force cylinder 12 is disposed opposite the slide 3, and the slide 3 is lowered by a pressure generating circuit 14 to which an accumulator 13 is connected. The output cylinder 4 is connected to a hydraulic tank 18 via a filler valve 17 via a pipe so that the output cylinder 4 can be filled with hydraulic oil.

The drive motor 8 is driven to rotate the hydraulic pump 6 to supply hydraulic oil to the output cylinder 4. Based on program setting values, a position detector 9 and a speed detector 10 are provided.
The position of the slide 3 is controlled and the speed is controlled by feeding back the signal (usually, the speed can be controlled from a position detector).

The slide 3 is moved by the position detector 9.
Is lowered to a predetermined position, and the pump 3 is gradually controlled to a pump rotation speed corresponding to the flow rate of the relief valve 7, and the slide 3 stops. If the predetermined position has been exceeded, the pump rotation speed is further reduced, and the oil of the output cylinder 4 escapes from the relief valve 7, so that the reaction force cylinder 1 of the reaction force generation circuit 14
The rise is corrected by the reaction force of 2.

As described above, since the slide 3 returns to the position above the predetermined position, the slide 3 can be controlled to be lowered to the predetermined position by always rotating the drive motor 8 without rotating the hydraulic pump 6 in the reverse direction. .

Also, despite the fact that the hydraulic pump 6 is always rotated in a fixed direction by the drive motor 8, a small amount of constant flow is released through the hydraulic oil release valve 7 so that the temperature inside the pump can be prevented from rising.

Further, as described above, since it is not necessary to perform control using a servo valve as in the prior art, hydraulic equipment,
The cleanliness of the pipeline can be reduced to the level of a general hydraulic device, and a commercially available normal hydraulic pump can be used, and the cost of manufacturing and maintaining the device can be reduced.

The reaction cylinder 12 normally generates a reaction force on the output cylinder 4 together with the accumulator 13, but when the slide 3 is to be lowered rapidly, the switching valve 16 of the pressure generation circuit 14 is switched to switch the slide. It can also be dropped using its own weight of 3. At this time, the filler valve 17 of the pilot operator is
Hydraulic oil can be quickly inhaled via the.

When it is desired to raise the slide 3 rapidly, the filler valve 17 of the pilot operating valve is forcibly opened, the pressure of the output cylinder 4 is released, and the slide cylinder 3 can be raised by the reaction force of the reaction force cylinder 12.

FIG. 2 shows another embodiment of the present invention, wherein the above-described relief valve 7 is a remote-controlled proportional solenoid valve, and when the slide 3 descends at high speed or medium speed, the relief valve 7 is closed. At the time of low-speed approach, the relief valve 7 is set to a required throttle amount at the time of pressure reduction so as to produce the same effect as described above.

In this embodiment, the hydraulic oil can be effectively used when the slide is at a high speed or a medium speed. These hydraulic controls can be easily performed by program setting of the control device.

FIG. 3 shows still another embodiment of the present invention.
The control valves 20 and 21 are connected, and the slide 3 is switched at high speed on the hydraulic circuit 1 for pressing.

In the above, the press apparatus has been described. However, the present invention can be similarly applied to a hydraulic pressure-lowering and pressing apparatus such as an injection molding apparatus, a rolling facility, and a machine tool. These hydraulic circuits are appropriately formed based on the gist of the present invention. Can be implemented.

[0024]

As described above, according to the present invention, in a pressing hydraulic circuit such as a press machine or a rolling facility, complicated control is not required by rotating the hydraulic pump forward and reverse. Also, there is no need for expensive and precise hydraulic control equipment such as servo valves, so there is no need to use special hydraulic pumps that can rotate in the normal and reverse directions. In addition, precise rolling speed and position control can be easily performed.

Further, a relief valve for releasing a predetermined flow rate is provided in a pressing hydraulic circuit between the output cylinder and the hydraulic pump even when the hydraulic pump is constantly rotated in a fixed direction. The rotation speed of the servomotor of the hydraulic pump is controlled based on the position command and speed command of the hydraulic pump, and the rotation speed is gradually reduced while supplying the oil amount more than the escape amount from the relief valve. Can be prevented.

If the same control is performed using a pump that can rotate forward and reverse without using a relief valve, if pressurization is continued at a fixed position for a long time, rotation will be maintained as much as leakage inside the pump. Since it is necessary, the temperature inside the pump rises, which may cause a failure.

Also, by controlling the output cylinder by applying a reaction force cylinder that constantly generates a repulsive force to the output cylinder, an elastic material, or an accumulated pressure, the hydraulic pump is always rotated in a fixed direction as described above. And can be easily controlled.

Further, the release valve is a valve that is capable of remotely controlling a variable flow rate, and a control valve for high-speed lifting is connected to the pressing hydraulic circuit so as to be openable and closable. Even if the valve is provided, the slide or the like can be pulled up at a high speed, and the device can be used efficiently.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram for explaining an embodiment of the present invention,

FIG. 2 is a circuit diagram of a relief valve according to the first embodiment;

FIG. 3 is an explanatory hydraulic circuit diagram of another embodiment of the above.

[Explanation of symbols]

1 ... Hydraulic circuit for pressing 4 ... Output cylinder 6
... Hydraulic pump 7 ... Relief valve 8 ... Drive motor 1
2 ... reaction cylinder

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Claims (3)

[Claims] 1. A pressing hydraulic control method in which an output cylinder is driven by a hydraulic pump to push down a pressing body such as a slide to a predetermined position, wherein the hydraulic pump is rotated by a driving motor such as a servomotor. In addition to controlling the number of drives, a relief valve for releasing a predetermined flow rate is provided in the pressing hydraulic circuit between the output cylinder and the hydraulic pump, and based on a position command or a speed command of the pressing body when the output cylinder is pressed. The rotational speed of a drive motor such as a servomotor that drives a hydraulic pump is variably controlled to gradually reduce the rotational speed while supplying the oil amount more than the escape amount from the relief valve, and to a predetermined position or a predetermined position. A hydraulic control method for pressing, characterized by controlling the position or speed of a pressing body at a speed. 2. The hydraulic control method for pressing according to claim 1, wherein the output cylinder is controlled by applying a reaction force cylinder, an elastic material, an accumulated pressure, or the like which constantly generates a repulsive force to face the output cylinder. 3. The pressing device according to claim 1, wherein the relief valve is a remotely controlled variable flow rate adjustable valve, and a control valve for high-speed lifting is connected to the pressing hydraulic circuit so as to be openable and closable. For hydraulic control method.