JPH0929500A - Device for vertically driving ram - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce oil hammering in a return circuit by retarding the raising/ lowering speed of a ram. SOLUTION: A flow control valve 13 is controlled by a controller in order to retard the raising/lowering speed of a ram 5, when a piston 21 is detected reaching a prescribed position against the pressing force of a spring 25 by a piston position detector 29, and also when a difference is small between the pressure detected by a first pressure detector 31 and that of a second pressure detector 33.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ram raising / lowering drive device for raising and lowering a ram in a press machine such as a punch press.

[0002]

2. Description of the Related Art Briefly explaining a conventional ram lifting drive device, a ram cylinder for lifting and lowering a ram is provided in a frame of this press machine. A flow control valve that can control the flow rate of the supply oil is installed in the middle of the supply circuit that connects the ram cylinder and the pump. A piston type accumulator capable of absorbing a part of the above is provided. Here, the piston type accumulator is
Accumulator main body, piston movably provided in the accumulator main body, return oil absorption chamber formed on one side of the piston in the accumulator main body and capable of absorbing return oil, and urging the piston to one side Equipped with possible springs.

Therefore, under the condition that the flow rate is controlled by the flow rate control valve, the supply oil is appropriately supplied from the supply circuit to the ram cylinder, whereby the ram is moved up and down and the work is pressed. On the other hand, as the ram moves up and down, return oil is discharged from the ram cylinder through the return circuit into the tank. Here, part of the return oil enters the return oil absorption hydraulic chamber and moves the piston in the other direction against the biasing force of the spring, so that the amount of movement of the piston from the pressure of the return oil (in other words, the spring). The pressure corresponding to the amount of contraction) can be reduced, and the oil hammer in the return circuit can be reduced.

[0004]

By the way, there is a relation that the pressure of the return oil in the return circuit is large when the ascending / descending speed of the ram is high, and the return oil pressure is small when the ascending / descending speed of the ram is slow. Therefore, if the ascending / descending speed of the ram is increased to increase the hit rate in a punch press (an example of a press machine), the pressure of the return oil in the return circuit becomes higher, and a part of the return oil returns. When entering the oil absorption chamber, the piston moves in the other direction against the urging force of the spring and hits the bottom of the accumulator body. Therefore, even if the pressure corresponding to the moving amount of the piston is reduced by the piston type accumulator, the pressure of the return oil is still high corresponding to the ascending / descending speed of the ram, and there is a problem that the oil hammer in the return circuit cannot be reduced.

[0005]

In order to solve the above-mentioned conventional problems, as a first means of the present invention, a ram cylinder for raising and lowering a ram in a press machine is provided, and this ram cylinder and pump are provided. A flow rate control valve that can control the flow rate of the supply oil is installed in the middle of the connected supply circuit, and a piston type accumulator that can absorb part of the return oil is installed in the middle of the return circuit that connects the ram cylinder and the tank. In the ram lifting drive device, the piston type accumulator is formed on the accumulator body, a piston movably provided in the accumulator body, and one side of the piston in the accumulator body and capable of absorbing return oil. A return oil absorption chamber and a spring capable of urging the piston toward one side. The first pressure detector for detecting the pressure of the return oil on the ram cylinder side of the piston type accumulator in the above is provided, and the second pressure detector for detecting the pressure of the return oil on the tank side of the return circuit on the ram cylinder side is provided. A control device is provided for controlling the flow rate control valve so that the ascending / descending speed of the ram becomes slow when the difference between the pressure detected by the first pressure detector and the pressure detected by the second pressure detector is small. It is characterized by

As a second means, a ram cylinder for raising and lowering a ram in a press machine is provided, and a flow rate control valve capable of controlling the flow rate of supply oil is arranged in the middle of a supply circuit connecting the ram cylinder and a pump. In a ram up-and-down drive device in which a piston type accumulator capable of absorbing a part of return oil is disposed in the middle of a return circuit connecting a ram cylinder and a tank, the piston type accumulator is the accumulator body and the inside of the accumulator body. A return oil absorption chamber which is formed on one side of the piston in the accumulator body and is capable of absorbing return oil, and a spring capable of urging the piston to one side, Detects that the piston has moved in the other direction against the biasing force of the spring and has reached a predetermined position. A piston position detector is provided, and a first pressure detector that detects the pressure of return oil on the ram cylinder side of the piston type accumulator in the return circuit is provided. A second pressure detector for detecting the pressure is provided, and when the piston position detector detects that the piston has reached a predetermined position against the biasing force of the spring, the first pressure detector detects the pressure. And a ram elevating and lowering device, characterized in that a control device for controlling the flow control valve is provided so that the elevating and lowering speed of the ram is slowed when the difference between the applied pressure and the pressure detected by the second pressure detector is small. Drive.

As a third means, in addition to the constitutional requirements of the first and second means, the predetermined position is the position of the piston when it strikes the bottom of the accumulator body, or slightly to one side of this position. It is characterized in that the position is closer to.

With the above-described structure, under the condition that the flow rate is controlled by the flow rate control valve, the supply oil is appropriately supplied to the ram cylinder from the supply circuit, so that the ram is raised and lowered to press the work. To do.

On the other hand, as the ram moves up and down, the return oil is discharged from the ram cylinder through the return circuit into the tank.
At this time, a part of the return oil enters the return oil absorption hydraulic chamber and moves the piston in the other direction against the urging force of the spring, whereby the amount of movement of the piston from the pressure of the return oil (in other words, the spring). The pressure corresponding to the amount of shrinkage can be reduced.

Under the above operation, the first pressure detector detects the pressure of the return oil on the ram cylinder side of the piston type accumulator in the return circuit, and the second pressure detector detects the piston type accumulator in the return circuit. Also detects the pressure on the tank side. Here, the first
When the difference between the pressure detected by the pressure detector and the pressure detected by the second pressure detector is large, it can be seen that the return oil in the return circuit has been sufficiently reduced in pressure by the piston type accumulator. When the difference is small, it can be seen that the depressurization of the return oil is insufficient. Further, when the piston position detector detects that the piston has reached a predetermined position against the biasing force of the spring,
It can be seen that the return oil in the return circuit has become high in pressure because the ram moves up and down at a high speed.

When the difference between the first pressure detector and the second pressure detector is small, the speed of the ram may be reduced by controlling the control device and the valve. When the piston position detector detects that the piston has reached a predetermined position against the biasing force of the spring, the pressure detected by the first pressure detector and the pressure detected by the second pressure detector are detected. When the generated pressure difference is small, the controller may control the flow control valve to slow down the ram lifting speed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A ram lifting / lowering drive device 1 according to this embodiment will be described with reference to FIG.

A frame 3 of a punch press (an example of a press machine) is provided with a ram cylinder 7 for raising and lowering a ram 5. Then, in the middle of the supply circuit 11 that connects the ram cylinder 7 and the pump P via the manifold 9,
A flow rate control valve 13 capable of controlling the flow rate of the supplied oil is provided, and a part of the returned oil can be absorbed in the return circuit 15 that connects the ram cylinder 7 and the tank T via the manifold 9. A piston type accumulator 17 is provided.

The piston type accumulator 17 is
The accumulator main body 19, a piston 21 provided in the accumulator main body 19 so as to be movable in the vertical direction (vertical direction in FIG. 1), and the accumulator main body 19
A return oil absorption chamber 23 formed below the piston 21 in the inside thereof and capable of absorbing return oil;
Is provided with a spring 25 capable of biasing downward.

In order to detect that the piston 21 has moved upwards against the urging force of the spring 25 and reached a predetermined position, the accumulator body 17 is provided with a rod 27 which is vertically movable. A movement amount detector (an example of a piston position detector) 29 is provided, and this rod 27 is connected to the piston 21. That is, the piston movement amount detector 29 electrically detects the movement amount of the rod 27, in other words, the vertical movement of the piston 21, thereby detecting that the piston 21 has moved upward and reached a predetermined position. To do. Instead of detecting the vertical movement amount of the piston 21, the limit switch and the connecting rod connected to the piston are used to
There is no problem even if it is detected that 1 has moved upward and reached a predetermined position. Further, the predetermined position refers to a position in the vertical direction of the piston 21 when the piston 21 strikes the bottom of the accumulator body 19, or a position slightly below the position in the vertical direction.

Between the piston type accumulator 17 and the ram cylinder 7 in the return circuit 15, there is arranged a first pressure detector 31 for detecting the pressure of the return oil on the ram cylinder 7 side of the piston type accumulator 17. Between the piston type accumulator 17 and the tank T in the return circuit 15, a second pressure detector 3 for detecting the pressure of return oil on the tank T side of the piston type accumulator 17 is provided.
3 is provided.

As shown in FIG. 2, the piston movement amount detector 29, the first pressure detector 31, and the second pressure detector 33.
Is connected to a control device 35, which is
When the piston movement amount detector 29 detects that the piston 21 has reached a predetermined position against the urging force of the spring 25, the pressure detected by the first pressure detector 31 and the second pressure When the pressure difference detected by the detector 33 is small, the flow control valve 13 is controlled so that the ascending / descending speed of the ram 5 becomes slow.

The operation of this embodiment will be described based on the above-mentioned configuration.

Under the condition that the flow rate is controlled by the flow rate control valve 13, by appropriately supplying the supply oil from the supply circuit 11 to the ram cylinder 7, the ram 5 is moved up and down to a work (not shown). Perform press processing.

On the other hand, as the ram 5 moves up and down, the return oil is discharged from the ram cylinder 7 through the return circuit 15 into the tank T. At this time, part of the return oil is absorbed in the return oil absorption chamber 23.
By entering the inside and moving the piston 21 upward against the biasing force of the spring 25, the pressure corresponding to the amount of movement of the piston 21 (in other words, the amount of contraction of the spring 23) from the pressure of the return oil is increased. The pressure can be reduced.

Under the above operation, the first pressure detector 31 detects the pressure of the return oil on the ram cylinder 7 side of the piston type accumulator 17 in the return circuit 15, and the second pressure detector 33 returns the return circuit. The pressure on the tank T side of the piston type accumulator 17 at 15 is detected. Here, when the difference between the pressure detected by the first pressure detector 31 and the pressure detected by the second pressure detector 33 is large, the return oil in the return circuit 15 is sufficiently decompressed by the piston type accumulator 17. It can be seen that when the difference is small, the depressurization of the return oil is insufficient. Further, when the piston movement amount detector 29 detects that the piston 21 has reached a predetermined position against the urging force of the spring 25, the return oil in the return circuit 15 is increased because the ram 5 moves up and down at a high speed. It can be seen that the pressure became high.

When the difference between the first pressure detector 31 and the second pressure detector 33 is small, the control device 35 and the valve 13 may be controlled to reduce the speed of the ram 5, or the piston movement When it is detected by the amount detector 29 that the piston 21 reaches a predetermined position by the urging force of the spring 25, the pressure detected by the first pressure detector 31 and the second pressure detector 33 are detected. When the pressure difference is small, the controller 35 may control the flow rate control valve 13 to slow down the lifting speed of the ram 5.

According to the invention according to the present embodiment as described above, the return circuit 1 is used because the ram 5 moves up and down at a high speed.
Even if the return oil in 5 is high pressure and the pressure reduction by the piston type accumulator 17 is insufficient, the control device 35 controls the flow rate control valve 13 to slow down the ascending / descending speed of the ram 5. As a result, the oil hammer in the return circuit 15 can be reduced.

[0024]

As can be understood from the above description of the embodiments, according to the invention described in claim 1 or 2, the return oil in the return circuit can be prevented due to a high ram moving speed. Even when the pressure is high and the pressure reduction by the piston type accumulator is insufficient, the flow rate control valve is controlled by the controller to slow down the ram ascending / descending speed to prevent the oil hammer in the return circuit. Can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic view showing a ram lifting drive device.

FIG. 2 is a control block diagram.

[Explanation of symbols]

 1 Ram up / down drive device 5 Ram 7 Ram cylinder 11 Supply circuit 13 Flow control valve 15 Return circuit 17 Piston type accumulator 19 Accumulator main body 21 Piston 23 Return oil absorption chamber 25 Spring 29 Piston movement amount detector 31 First pressure detector 33 Third 2 Pressure detector 35 Control device

Claims (3)

[Claims] 1. A ram cylinder for raising and lowering a ram in a press machine is provided, and a flow control valve capable of controlling the flow rate of supply oil is provided in the middle of a supply circuit connecting the ram cylinder and a pump, and the ram cylinder and the tank. In a ram lifting drive device in which a piston type accumulator capable of absorbing a part of return oil is arranged in the middle of a return circuit connecting the above, the piston type accumulator is movable to the accumulator body and the accumulator body. A piston provided, a return oil absorption chamber formed on one side of the piston in the accumulator body and capable of absorbing return oil, and a spring capable of urging the piston to one side. The first pressure detector that detects the pressure of return oil on the ram cylinder side of the piston type accumulator. And a second pressure detector for detecting the pressure of the return oil on the tank side of the piston type accumulator in the return circuit. The pressure detected by the first pressure detector and the second pressure detector are detected by the second pressure detector. A ram raising / lowering drive device is provided with a control device for controlling the flow rate control valve so that the raising / lowering speed of the ram becomes slower when the pressure difference is small. 2. A ram cylinder for raising and lowering a ram in a press machine is provided, and a flow control valve capable of controlling the flow rate of supply oil is provided in the middle of a supply circuit connecting the ram cylinder and a pump, and the ram cylinder and the tank. In a ram lifting drive device in which a piston type accumulator capable of absorbing a part of return oil is arranged in the middle of a return circuit connecting the above, the piston type accumulator is movable to the accumulator body and the accumulator body. A piston provided, a return oil absorption chamber formed on one side of the piston in the accumulator body and capable of absorbing return oil, and a spring capable of urging the piston to one side. Piston position detection that detects when a predetermined position is reached by moving in the other direction against the urging force of the And a first pressure detector for detecting the pressure of the return oil on the ram cylinder side of the piston type accumulator in the return circuit, and the pressure of the return oil on the tank side of the return circuit for the piston type accumulator. A second pressure detector is provided, and when the piston position detector detects that the piston has reached a predetermined position against the biasing force of the spring, the pressure detected by the first pressure detector is detected. And the second
When the pressure difference detected by the pressure detector is small,
A ram lifting / lowering drive device comprising a controller for controlling the flow rate control valve so that the ram lifting / lowering speed becomes slower. 3. The predetermined position is the position of the piston when it strikes the bottom of the accumulator body, or a position slightly closer to one side than this position. The ram lifting drive described.