JPH087934Y2 - Press brake hydraulic circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a hydraulic circuit for supplying pressure oil to a hydraulic cylinder that moves a ram up and down in a press brake suitable for bending a long plate.

[Conventional technology]

As a press brake, a hydraulic press brake is known in which a ram with an upper mold is moved up and down by a pair of left and right hydraulic cylinders, and a long plate is bent by a lower mold provided on a table. As a hydraulic circuit for supplying pressure oil, for example, one shown in FIG. 2 is known.

That is, the hydraulic cylinder 1 has the first and second expansion chambers 2 and 3 and the reduction chamber 4, and the discharge pressure oil of the pump 5 is supplied to one of the first and second passages 7 and 8 by the solenoid valve 6. The pressure oil in the first passage 7 is supplied to one of the first extension chamber 2 and the reduction chamber 4 by the first and second servo valves 9 and 10, and the pressure oil in the second passage 8 is supplied to the second extension chamber. 3 and the solenoid valve 6 when the ram descends at high speed.
The solenoid 6a is energized to the first position I to supply the pressure oil of the pump 5 to the second extension chamber 3 and the motor 11
Switch the first and second servo valves 9 and 10 to the extension position B to extend the hydraulic cylinder 1, and the first and second servo valves 9 and 10
By controlling the switching stroke of 10 with the motor 11 and adjusting the throttle, the flow rate of the oil in the reduction chamber 4 flowing out to the tank 12 is controlled, and the ram is synchronized with the speed adjustment and the lowering of the left and right hydraulic cylinders 1. I am trying to descend in parallel.

When the ram slows down, the solenoid 6a of the solenoid valve 6 is not energized and the second extension chamber 3 is connected to the tank as the second position II, and the motor 11 sets the first and second servo valves 9 and 10 to the extension position B. , The hydraulic pressure is supplied to the first expansion chamber 2 and the pressure oil in the reduction chamber 4 flows out to the tank 12, but at this time the capacity of the first expansion chamber 2 is large and the amount of supplied pressure oil is insufficient, so the filling valve (Suction valve) 13 sucks the pressure oil in the tank by dropping the ram by its own weight.
By adjusting the switching stroke of the second servo valves 9 and 10 to change the throttle, the flow rate of the pressure oil in the reduction chamber 4 flowing out to the tank 12 is controlled to perform speed adjustment and parallel adjustment.

When the ram is raised, the solenoid valve 6 is set to the second position II and the motor 11
Then, the first and second servo valves 9 and 10 are set to the reduced position A to supply pressure oil to the reduction chamber 4, and the pressure oil in the first extension chamber 2 is passed through the first and second servo valves 9 and 10. The pressure oil in the second extension chamber 3 flows out to the tank from the electromagnetic valve 6 to the tank to reduce the hydraulic cylinder 1 and raise the ram.

[Problems to be solved by the device]

With such a hydraulic circuit, when the ram descends, the flow rate of the pressure oil in the reduction chamber 4 to the tank is controlled by the first and second servo valves.
Speed adjustment and parallel adjustment by squeezing with 9,10, speed adjustment by squeezing the flow rate and pressure of pressure oil supplied into the reduction chamber 4 with the first and second servo valves 9,10 when the ram rises, Although parallel adjustment is made, the pressure oil in the second expansion chamber 3 flows out to the tank from the solenoid valve 6, so the pressure supplied to the reduction chamber 4 of the hydraulic cylinder 1 and the outflow are the same at the start of the ram rise. However, the reduction speed of the left and right hydraulic cylinders 1 may differ due to the difference in sliding resistance between the left and right hydraulic cylinders 1 and the ram may rise while fluctuating left and right, which may wear the guide portion of the ram and the like. This is not preferable.

Therefore, an object of the present invention is to provide a hydraulic circuit for a press brake which can solve the above-mentioned problems.

[Means and Actions for Solving the Problems]

The hydraulic circuit of the present invention is a press brake in which a ram is moved up and down by a pair of left and right hydraulic recliners 1 to bend a plate material between an upper die and a lower die, and the pair of left and right hydraulic cylinders 1 are
The first extension chamber 2, the second extension chamber 3, and the reduction chamber 4 are provided, and the discharge pressure of the pump 5 is applied to one or the other of the second extension chamber 3 and the reduction chamber 4 of the pair of hydraulic cylinders 1 on the left and right. Extension position B for supplying oil and communicating the other or one with tank 12
And a shut-off position D for connecting the first expansion chamber 2 and the tank 12 via a throttle, and a communication for connecting the first expansion chamber 2 to the second expansion chamber 3. A solenoid valve 24 that can be switched to the position C is provided so that the solenoid valve 24 is set to the shutoff position D when the ram is raised and lowered at high speed, and the communication valve C is set to the communication position C when the ram is lowered slowly. Thus, the ram can be lowered at a high speed or a slow speed, and when the ram is raised, the flow rate of the return oil from the second extension chamber 3 of the hydraulic cylinder 1 to the tank can be controlled, and the sliding resistance of the left and right hydraulic cylinders 1 can be controlled. The ram can be raised in parallel even if there is a difference.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. It should be noted that the same members as those in the related art have the same reference numerals.

A check valve 21 is provided in the circuit 20 which supplies the discharge pressure oil of the pump 5 to the inlets 9a, 10a of the first and second servo valves 9, 10, and the first port 9b, of the first and second servo valves 9, 10 is provided. 10b is connected to the reduction chamber 4 of the hydraulic cylinder 1, and the second ports 9c and 10c are connected.
Is connected to the second expansion chamber 3 by the first circuit 22, and the second circuit 23 connected to the first expansion chamber 2 is connected to the first circuit 22 and one of the tanks 12 by the solenoid valve 24.

 Next, the operation will be described.

When the ram is raised, the solenoid valve 24 is set to the shutoff position D, and the motor 11
Then, the first and second servo valves 9 and 10 are set to the reduction position A, and the discharge pressure oil of the pump 5 is supplied to the reduction chamber 4 through the check valve 21, and the pressure and flow rate are set to the first and second servo valves 9 and 10. It is adjusted by the diaphragm with 10 and 10 switching strokes. Further, the pressure oil in the first extension chamber 2 flows into the tank 12 via the second circuit 23 and the restriction of the shutoff position D of the solenoid valve 24, and the pressure oil in the second extension chamber 3 is transferred to the first and second servo valves 9 and 9. Tank with 10 apertures
Since the flow rate to 12 is adjusted, it flows into the hydraulic cylinder 1,
Since the flow rate of the pressure oil flowing out is controlled by the throttle by the switching stroke of the first and second servo valves 9 and 10, it is possible to stably raise the rams in parallel while the left and right hydraulic cylinders 1 have the same reduction speed.

When the ram is descending at high speed, the motor 11 sets the first and second servo valves 9 and 10 to the extended position B, and the solenoid valve 24 is set to the shut-off position D shown in the drawing to discharge the pressure oil from the pump 5 to the first and second servo valves. It is supplied to the second expansion chamber 3 with a small capacity via 9 and 10, and the pressure oil in the reduction chamber 4 also flows out to the tank 12 through the first and second servo valves 9 and 10, so the hydraulic pressure is the same as before. A stable system is achieved by controlling the flow rate of the pressure oil flowing in and out of the cylinder 1 by restricting the first and second servo valves 9 and 10. The pressure oil in the tank is sucked into the first expansion chamber 2 having a large capacity from the filling valve 13.

When the ram slows down, the solenoid valve 24 is switched to the communication position C, and the pressure oil discharged from the pump 5 is supplied to the first and second extension chambers 2 and 3 via the first and second servo valves 9 and 10 to reduce the pressure. Since the pressure oil in the chamber 4 also flows out to the tank 12 through the first and second servo valves 9 and 10, the flow rate of the pressure oil flowing into and out of the hydraulic cylinder 1 is the same as that at the time of the high speed descent of the ram. It is controlled by the throttle of the second servo valves 9 and 10.

[Effect of device]

A pump 5 is installed in the second extension chamber 3 of the pair of left and right hydraulic cylinders 1.
The discharge pressure oil of is supplied through the servo valve, and the reduction chamber 4
The ram can be lowered at a high speed by letting out the pressure oil in the tank to the tank via the servo valve, and the pressure oil discharged from the pump 5 to the first and second extension chambers 2 and 3 of the pair of left and right hydraulic cylinders 1 via the servo valve. The ram can be moved down slowly by supplying the pressure oil in the reduction chamber 4 to the tank via the servo valve.

Therefore, the ram can descend at a high speed and a low speed, and at that time, even if there is a difference in sliding resistance between the left and right hydraulic cylinders 1 by controlling the flow rate of the pressure oil flowing in and out of the hydraulic cylinder 1 by the throttle of the servo valve. Can descend in parallel.

Further, the discharge pressure oil of the pump 5 is supplied to the reduction chambers 4 of the pair of left and right hydraulic cylinders 1 via the servo valve, and the pressure oil in the first extension chamber 2 is passed through the cutoff position D of the solenoid valve 24. The ram can be raised by flowing out the pressure oil in the second extension chamber 3 into the tank through the servo valve, and at that time, the flow rate of the pressure oil flowing in and out of the hydraulic cylinder 1 is reduced by the servo valve. The ram can be raised in parallel even if there is a difference in sliding resistance between the left and right hydraulic cylinders 1 by controlling.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention, and FIG. 2 is a conventional hydraulic circuit diagram. 1 is a hydraulic cylinder, 2 is a first extension chamber, 3 is a second extension chamber,
4 is a reduction chamber, 5 is a pump, 9 and 10 are first and second servo valves, and 24 is a solenoid valve.

Claims (1)

[Scope of utility model registration request] 1. A press brake in which a ram is moved up and down by a pair of left and right hydraulic cylinders 1 to bend a plate material between an upper die and a lower die, wherein the pair of left and right hydraulic cylinders 1 are connected to a first extension chamber 2 and a second extension chamber 2. An extension chamber 3 and a reduction chamber 4 are provided, and the discharge pressure oil of the pump 5 is supplied to one or the other of the second extension chamber 3 and the reduction chamber 4 of the pair of left and right hydraulic cylinders 1 and the other or A servo valve for switching one to the extended position B or the reduced position A, which communicates with the tank 12, is provided, and the shut-off position D for communicating the first expansion chamber 2 with the tank 12 via a throttle and the first expansion chamber 2 therefor. Is provided with a solenoid valve 24 that is switched to a communication position C that communicates with the second extension chamber 3. When the ram is raised and lowered at a high speed, the solenoid valve 24 is set to a shutoff position D, and when the ram is lowered slowly, the solenoid valve 24 is connected. Oil for the press brake that is set to position C Pressure circuit.