JPH0985499A - Slide driving device for hydraulic press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic press excellent in positional accuracy of the bottom dead center of a slide, suppressible in vibration at the press work time and capable of being operated at a high speed. SOLUTION: A slide is lowered highly speedily to just before press work is started, pressing is executed with the signal of a lower sensor 25 detecting the position of lowering speed change, reaching the bottom dead center of lowering being restricted with a stopper, after pressing pressure is held for a fixed time, the slide is raised at a high speed. For supplying and discharging the pressured oil to an upper hydraulic room 3A of the upper side of a piston 4 of a hydraulic cylinder 3 to drive the slide, a directional flow controlling valve 16 is used, the pressure oil is always supplied in a lower hydraulic room 3B of the lower side of the piston 4, and raising and lowering of the slide 5 and the speed are controlled by controlling the supplying or discharging flow of the pressure oil of the upper hydraulic room 3A on the side of lowering the slide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of controlling the ascending / descending speed of a slide of a hydraulic press.

[0002]

2. Description of the Related Art In a slide drive device for a hydraulic press, the descending speed of the slide is switched to a high speed until the middle of the descending, and to a low speed from immediately before a pressing force such as punching acts on the slide to descend to a bottom dead center. After reaching, there is the following conventional technique in which the ascending speed is high and the slide stroke time is shortened.

Actual open flat 3 using a plurality of directional valves in parallel
In the first prior art of No. -36398, when descending a slide, first, all of the plurality of directional control valves are operated to the descending operation side, pressure oil is supplied to descend the slide at a high speed, and then the slide is moved downward. During the descent, a part of the plurality of directional control valves is operated to the closing side and pressure oil is supplied by the remaining part of the directional control valves to lower the slide at a low speed. When the slide reaches the lower limit (bottom dead center), all of the directional control valves are switched to the raising operation side to raise the slide at high speed, and when the slide reaches the upper limit, the directional control valve is operated to the closing side. The slide is stopped.

In the second prior art of FIG. 5 using the directional flow control valve 31, the directional flow control valve 31 is placed on the descending operation side 31.
It is used by switching to A, closing 31B, and ascending operation side 31C.

The third prior art of Japanese Patent Laid-Open No. 1-148500, which uses a servo valve for detecting the position of the slide and performing feedback control, changes the speed and positions the position as compared with the above-described directional switching valve and directional flow control valve. The accuracy (bottom dead center) is improved.

[0006]

In the first prior art of Japanese Utility Model Laid-Open No. 3-36398, which uses a plurality of directional control valves in parallel, the speed of the slide is changed depending on the number of directional control valves used. It is possible to change at a fixed speed, but the bottom dead center position varies due to the inability to adjust the speed steplessly, the response time of the directional control valve varies, etc., and it can be held under pressure at the bottom dead center position. There is no directional switching valve, and it takes a long response time to operate the directional switching valve from the descending operation side to the ascending operation side.When switching between these directional switching valves, another directional switching valve, etc. is used to reduce the impact on the slide. There was a drawback such as having to provide.

In the second prior art of FIG. 5 using the directional flow control valve 31, the slide 33 reaches the lower limit, and the directional flow control valve 31 is moved from the lower operation side 31A to the upper operation side 31C.
However, due to the signal from the sensor 32, the low-speed descent passes through the halfway closed part and switches to the ascending operation side. Therefore, the bottom dead center position varies due to the variation in the response time of the directional flow control valve 31. . Further, the pressure oil changes from supply to discharge on the descending operation side and from discharge to supply on the ascending operation side, and the change in the flow rate of the pressure oil in a minute time increases, so the acceleration acting on the slide 33 increases, For this reason, there is a drawback that the change in speed becomes large, and as a result, the slide 33 vibrates and the life of the mold is shortened.

In the third prior art of Japanese Patent Laid-Open No. 1-148500 using a servo valve for detecting the position of the slide and performing feedback control, the servo valve and its control device are expensive, and the directional control valve and the directional flow control valve are used. Cheap sensor,
For example, a limit switch is good, but a servo valve requires an expensive slide displacement sensor, and since the servo valve is prone to failure due to dust in the oil, it has to have a filter to remove minute dust. was there.

[0009]

In order to eliminate these drawbacks of the prior art, the present invention provides a slide drive device having the following mechanism. The directional flow control valve is connected to the upper hydraulic chamber of the cylinder for lowering the slide of the hydraulic press, and supplies and discharges pressure oil. Pressure oil is constantly supplied to the lower hydraulic chamber of the piston of the cylinder for raising the slide, and when the pressure of the pressure oil rises abnormally, this pressure oil is discharged by the relief valve.

When the directional flow control valve is operated to a large flow rate on the slide lowering side, pressure oil is supplied to the upper hydraulic chamber of the cylinder for lowering the slide of the hydraulic press, and the slide is rapidly lowered until just before the pressurization is started. Then, the directional flow control valve is operated to a small flow rate by the signal of the upper sensor that detects the slide lowering speed changing position, and the slide is lowered at a low speed. When the slide reaches the lower limit and comes into contact with the stopper, the slide cannot be lowered, but the directional flow control valve is kept in the low speed descending state, and the pressure of the supplied pressure oil, that is, the pressing force acting on the slide is kept. Keep it for a certain period of time,
The surplus pressure oil supplied is discharged from the throttle valve.

When the directional flow control valve is actuated to the slide up side after a certain period of time, the hydraulic oil filled in the upper hydraulic chamber is discharged by the pressure oil constantly supplied to the lower hydraulic chamber, and the slide moves at high speed. The directional flow control valve is activated by the signal from the upper sensor that detects the position of the ascending limit, and the amount of pressure oil that is the same as or slightly larger than the amount discharged by the throttle valve is maintained. The slide will either stop at the ascending end or slightly ascend while waiting for the start of the next cycle.

[0012]

1 to 4 show an embodiment of the present invention.
This will be described below. A slide 5 of the hydraulic press 1 is fixedly mounted on a piston 4 provided on the hydraulic cylinder 3.
An upper hydraulic chamber 3A is provided above the piston 4 of the hydraulic cylinder 3.
However, a lower hydraulic chamber 3B is provided on the lower side. The mold 6 is composed of an upper mold 6A and a lower mold 6B, and the slide 5 has an upper mold 6A.
However, the lower die 6B is fixedly installed on the bolster 2 of the hydraulic press 1. The lower die 6B is provided with stoppers 7 and 7. When the upper die 6A comes into contact with the stoppers 7 and 7, the upper die 6A cannot be further lowered.

The hydraulic oil in the oil tank 10 is pressurized by the pump 11, is supplied as pressure oil to the pipe line 12, is passed through the check valve 14, and is connected by the pipe line 15 to the directional flow control valve. 16 and the lower hydraulic chamber 3B connected by the conduit 22. Further, the directional flow control valve 16 and the upper hydraulic chamber 3A are connected by a pipe line 17, and branched from the pipe line 17 to branch the throttle valve 1
8, a pipe line 19, a check valve 20, and a pipe line 21 are provided and connected to the oil tank 10. Further, a relief valve 23 is provided branching from the pipe line 22, is connected to the pipe line 19, and is connected to the oil tank 10 via the check valve 20 and the pipe line 21.

An upper sensor 26 for detecting the upper limit position of the slide 5 and a lower sensor 25 for detecting a deceleration position provided at a speed changing position immediately before a pressurizing area such as punching.
Is provided on the frame of the hydraulic press 1 so as to be vertically adjustable. The control device 27 includes an upper sensor 26 and a lower sensor 2
5. The input signal from the cycle start signal 28 is obtained to drive and control the directional flow control valve 16.

In this structure, the control device 27 controls the slide 5 in the following procedure. The slide 5 moves from the upper limit position S1 where the upper sensor 26 operates to the upper limit position S1.
When the cycle start signal 28 is obtained in a state between 0 (slide rising fixed position), the directional flow control valve 16 is set to 16A.
On the side, the flow rate of the pressure oil is increased to lower the slide 5 at a high speed.

After that, when the lower sensor 25 operates to obtain the signal 25A, the directional flow control valve 16 is operated in a state where the flow rate of the pressure oil is small while keeping the 16A side, and the slide 5 is lowered at a low speed.

While the slide 5 is descending at high speed and low speed, the pressure oil filled in the lower hydraulic chamber 3B is discharged from the relief valve 23.

Further, the slide 5 descends, and the upper die 6A
Comes into contact with the stoppers 7, 7 provided on the lower mold 6B,
The slide 5 cannot be lowered and stops. This position is
It is the bottom dead center position of the slide.

The directional flow control valve 16 holds the slide 5 in the state of descending at a low speed as it is, and while the pressure of the pressure oil is kept as it is, the pressure oil supplied to the upper hydraulic chamber 3A is supplied from the throttle valve 18. It is discharged to the oil tank 10. In this state, the slide 5 is kept in a state in which a pressing force is applied.

After a lapse of a certain time, the directional flow control valve 16 is switched to the high flow rate state on the 16C side, discharging the hydraulic oil filled in the upper hydraulic chamber 3A and constantly in the lower hydraulic chamber 3B. The pressure oil supplied causes the slide 5 to rise at a high speed.

When the upper sensor 26 is actuated by the rise of the slide 5 and the signal 26A is obtained, the directional flow control valve 16 actuates the flow rate minutely on the side of 16A, and the slide 5 stops or rises at a fine speed. Ready to go.

The hydraulic press 1 is constructed and controlled in this way.
When the slide 5 is driven, the value obtained by subtracting the pressurizing force that constantly raises the slide 5 from the pressurizing force that lowers the slide 5 becomes the net pressurizing force that lowers the slide 5 that can be used for press work such as punching. There is a problem that the pressure oil discharged from the throttle valve 18 while the slide 5 is descending and at the bottom dead center causes energy loss because it does not perform any work. However, the problems of the reduction of the pressing force and the energy loss are negligible in a hydraulic press having a small pressing force.

The directional flow control valve 16 uses the control device 27 which can arbitrarily set the control amount for making the flow rate of the hydraulic oil supplied to and discharged from the upper hydraulic chamber 3A large, small or minute. Since it can be done, along with the press processing,
It goes without saying that this control amount may be set in the control device 27 in advance.

In this embodiment, the stopper 7 is attached to the mold 6.
However, it goes without saying that the bottom dead center position of the slide 5 may be regulated by providing it between the slide 5 of the hydraulic press 1 and the bolster 2.

[0025]

According to the first prior art, the flow rate at each stage is fixed by the number of the plurality of directional control valves, that is, the slide speed can be controlled to the fixed high speed and the fixed low speed. On the other hand, the slide speed in the present invention can be controlled to any high speed and any low speed.

In the first and second prior arts, the slide cannot be held in a pressed state at the bottom dead center, but in the present invention, it can be held. Further, in the first and second prior arts, it is difficult to make the positional accuracy of the bottom dead center of the slide constant, but in the present invention, it can be kept constant. In addition, the first and second
In the related art, the pressure oil is supplied and discharged by the directional switching valve and the directional flow control valve when the slide moves up and down. However, in the present invention, since the lower hydraulic chamber for raising the slide is a meter-in / meter-out circuit for constantly supplying pressure oil, almost no impact is generated on the slide, Therefore, the shock absorbing mechanism is unnecessary.

In the third prior art, an expensive sensor such as a linear sensor for detecting the position of the slide and an expensive control device for feedback control are required, but in the present invention, an inexpensive sensor such as a limit switch and on / off control are performed. An inexpensive control device will do. Further, in the third prior art, a hydraulic pressure generating device provided with a filter for removing minute dust in hydraulic oil causes malfunction, but in the present invention, the same simple hydraulic pressure as in the first and second prior arts is used. It can be a generator.

As described above, according to the present invention, the control capability is comparable to that of the slide driving device using the servo valve of the prior art, and the control capability is higher than that of the plural directional control valves or the directional flow control valve of the prior art. It is possible to provide a slide driving device having the above.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a hydraulic press that is an embodiment of the present invention.

FIG. 2 shows a circuit diagram of a main part of the present invention.

FIG. 3 shows a relationship diagram between a slide position and elapsed time.

FIG. 4 is a diagram showing a relationship between supply / discharge of pressure oil to an upper hydraulic chamber and elapsed time.

FIG. 5 shows a circuit diagram of the main part using a prior art directional flow control valve.

[Explanation of symbols]

1 is a hydraulic press, 2 is a bolster, 3 is a hydraulic cylinder, 3
A is an upper hydraulic chamber, 3B is a lower hydraulic chamber, 4 is a piston, 5 is a slide, 6 is a mold, 6A is an upper mold, 6B is a lower mold, 7 is a stopper, 10 is an oil tank, 11 is a pump, 12, Fifteen, one
7, 19, 21, 22 are pipe lines, 14, 20 are check valves, 1
6 is a directional flow control valve, 18 is a throttle valve, 23 is a relief valve, 24 is an accumulator, 25 is a lower sensor, 25A is a signal from the lower sensor 25, 26 is an upper sensor, 26A is a signal from the lower sensor 26, and 27 is a control. A device, 28 is a hydraulic press cycle start signal, S0 is a slide upper limit position, S1 is a slide rising limit, and T1 is a timer setting time of the control device.

Claims (1)

[Claims] 1. A slide drive device for raising and lowering a slide of a hydraulic press, comprising: (a) a stopper that regulates a lower limit of the slide, an upper hydraulic chamber above a piston of a hydraulic cylinder that drives the slide, and a discharge of a hydraulic pump. A directional flow control valve provided in the middle of a pipe connecting the outlet, a pipe connecting the discharge port to a lower hydraulic chamber on the lower side of the piston, and a pipe connecting the upper hydraulic chamber and an oil tank. A throttle valve provided in the middle of the road, an upper sensor for detecting the position of the ascending limit during the work of the slide, a lower sensor for detecting the speed change position during the descending operation, and a control device for controlling these are provided. (B) When the operation start signal of the hydraulic press is obtained, the directional flow control valve is controlled to supply the pressure oil to the upper hydraulic chamber, and the slide interlocking with the piston is lowered at a high speed. (C) Subsequently, when the signal from the lower sensor is obtained, the directional flow control valve is controlled to reduce the supply amount of the pressure oil to lower the slide interlocking with the piston at a low speed. (D) After that, the slide stops being lowered by the stopper, and the slide is kept in that state for a predetermined time. (E) Subsequently, the directional flow control valve is controlled to discharge the oil supplied to the upper hydraulic chamber to the oil tank, and the directional flow control valve is controlled by a signal from the upper sensor. Then, the pressure oil that is the same as or slightly smaller than the discharge amount from the throttle valve is supplied to the upper hydraulic chamber, and the slide is stopped or the rising speed is slightly increased. A slide drive device for a hydraulic press having the above configuration.