JPH0829366B2 - Die cushion device for press machine - Google Patents

Description

The present invention relates to a die cushion device for a press machine.

[Prior Art] FIG. 4 shows an example of a conventional die cushion device of a press machine. A lower die c is provided on a bolster plate b provided on a bed a, and the bolster plate b is further provided. A blank holder e, which penetrates and receives the material d at the upper end, is provided, and a cushion pad g provided at the lower end of the blank holder e is supported on a die cushion h composed of a plurality of stages of air cylinders. The upper mold i descends and the material d is clamped by pressing the material d against the blank holder e so that the material i is clamped, and the mold i descends while compressing the die cushion h in the clamped state. By doing so, the material d is formed by the upper and lower molds i and c. In the figure, j indicates a soundproof wall provided so as to cover the press device, and k indicates an opening / closing door provided for moving the mold in and out of the soundproof wall j.

[Problems to be Solved by the Invention] However, in the press machine as described above, when the upper die i is pre-accelerated and hits the material d first (the upper die i and the blank holder e clamp the material). ), The blank holder e
Causes a loud noise (metal sound) when hitting a stopper (not shown) at the raised upper limit position, and particularly a striking impact sound when the upper die i hits the material d for the first time, which is a problem. .

Therefore, conventionally, a heavy soundproof wall j is provided, and at this time, an opening / closing door k is provided on the soundproof wall j in order to replace the upper and lower molds c and i. In spite of having a very large and expensive structure, the sound insulation was not so effective.

Further, in the die cushion h by the air cylinder as described above, since the cushion force is obtained by compressing the air in the air cylinder, the size is increased, and the cushion force is increased with the descending stroke. There is a problem in that the clamping force of the material becomes excessively large due to this increase and the material d is cracked or wrinkled.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to freely adjust the pressing force using a small hydraulic cylinder and to prevent the generation of a large noise accompanying the press work. .

[Means for Solving the Problems] The present invention includes an upper mold that can move up and down, a lower mold that does not move up and down, and a blank holder that can move up and down to clamp a material between the upper mold and the lower mold. In a die cushion device of a press machine, the blank holder is supported by a hydraulic cushion cylinder and a hydraulic lifting cylinder so as to be able to move up and down, and a flow path for supplying oil is connected to each of upper and lower oil chambers of the hydraulic lifting cushion cylinder. In addition, a switching valve and a servo valve are used to switch the upper and lower oil chambers to connect a flow path for discharging oil, and a lower oil chamber of the hydraulic pressure rising cylinder is connected to a flow path for supplying and discharging oil. Input a detection signal from the position detector that detects the mold position and send a control signal to adjust the flow rate to the servo valve based on the setting signal from the setting device that sets the relationship between the upper mold position and the pressing force. A die cushion device for a press machine is provided by providing a control device.

[Operation] Therefore, in the present invention, since the hydraulic cushion cylinder and the hydraulic lifting cylinder are used, the size of the device can be reduced as compared with the case where the conventional air cylinder is used. Further, the control device sends a control signal to the servo valve based on the setting signal from the setting device by the input of the detection signal indicating the position of the upper die from the position detector, and the servo valve is the hydraulic cushion switched by the switching valve. The oil is discharged from one of the upper and lower oil chambers of the cylinder, and in this case, the oil is discharged from the lower oil chamber to control the pressing force of the hydraulic cushion cylinder and adjust the lowering speed of the blank holder. By discharging the oil from the chamber, the hydraulic pressure raising cylinder is extended and the blank holder is raised.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

 FIG. 1 is an explanatory view of one embodiment of the present invention.

On the lower surface of the fixed base 1, vertically oriented hydraulic cushion cylinders 2 and 3 and a hydraulic lifting cylinder 4 are arranged, and pistons 5 and 6 fitted in the hydraulic cushion cylinders 2 and 3 and the hydraulic lifting cylinder 4 so as to be vertically movable. Piston rods 8, 9 and 10 that extend upward through the fixing base 1 are integrally attached to the and 7, respectively.

A cushion pad 11 is attached to the upper end of the piston rods 8, 9 and 10 and a blank holder is placed on the cushion pad 11.
12 is installed.

The oil in the tank 13 is pump 14, filter 15, check valve 1
6, so that it can be supplied from the flow path 20 to the upper oil chambers 21, 22 of the hydraulic cushion cylinders 2, 3 through the intake port 18 of the logic valve 17 and the discharge port 19 of the logic valve 17, which will be described later. ing.

Further, in the upper oil chambers 21 and 22, a flow path 29 having a check valve 28,
The oil in the tank 13 can be sucked in via the flow path 20.

The logic valve 17 has a port 18 for suction and a port 19 for discharge as well as a port 23 for pilot operation on the outside, and a spring internally shuts off between the port 18 for suction and the port 19 for discharge. Equipped with a stroke limiter 63 that adjusts the stroke of the poppet 24 and the poppet 24 that are constantly urged in the direction of Depending on the size, the poppet 24 moves to the side with a smaller pressure, opens and closes the port 18 for suction and the port 19 for discharge, and changes the opening by using the stroke limiter 63 to adjust the amount of oil flowing between them. The port for pilot operation of the logic valve 17
23 is a flow path provided with an accumulator 25 and a solenoid valve 26 capable of accumulating oil from upstream of the logic valve 17 of the flow path 20.
Can be supplied via port 27 and port 23
Oil from the tank 13 via the solenoid valve 26 and the flow path 30.
It can be discharged to.

The upper oil chambers 21 and 22 and the lower oil chambers 31 and 32 of the hydraulic cushion cylinders 2 and 3 are connected to the flow paths 20, 33 and 34, respectively, and the switching valve 3
5. Oil can be discharged to the tank 13 through the flow path 37 provided with the servo valve 36.

Further, the oil in the tank 13 can be sucked into the lower oil chambers 31 and 32 through a flow passage 39 and a flow passage 34 each having a check valve 38.

In the lower oil chamber 40 of the oil pressure raising cylinder 4, oil is decompressed from the upstream side of the logic valve 17 of the flow passage 20 by a pressure reducing valve 41 and an accumulator.
It is adapted to be supplied via a flow path 43 accompanied by 42, and the upper oil chamber 44 is open to the atmosphere (tank
You may open it to 13.)

Lower oil chamber 32 and upper oil chamber of the hydraulic cushion cylinder 3
Pressure sensors 48 and 49 are provided to detect the hydraulic pressure of 22 separately and to input the detection signals 45 and 46 to the comparator 47, which is adapted to obtain the pressing force by taking the deviation between the two, and further the upper die 50 A position detector such as a rotary encoder 52 for detecting the rotational angle position of the ascending / descending press drive device 51, that is, the position of the upper die 50 is provided, and a detection signal 53 from the rotary encoder 52 and a deviation signal 54 from the comparator 47 are arranged. A control device 57 for inputting a setting signal 56 that sets the relationship between the pressing force from the setting device 55 and the rotational angle position is provided to the control device 57, and the servo valve 36 is controlled by the control signal 58 from the control device 57. .

In the figure, 59 is a lower die fixed to the bolster plate, 60 is a material, 61 and 62 are relief valves, and 63 is a stroke limiter.

Next, the operation will be described.
Accumulator 42 is accumulated in advance by passing pressure oil through 20,43.

When the upper die 50 is raised, the switching valve 35 is switched to the E side, the servo valve 36 is switched to the C side, and the oil in the upper oil chambers 21 and 22 of the hydraulic cushion cylinders 2 and 3 is passed through the flow paths 20, 33, and. The oil from the tank is discharged to the tank 13 through the 37 and the oil in the tank flows to the lower oil chambers 31 and 32.
Accumulator 42 with suction through 9,34
The oil is supplied to the lower oil chamber 40 of the hydraulic pressure increasing cylinder 4 by the pressure of (1) to raise the cushion pad 11 to the set upper limit position, and in this state, the servo valve 36 is closed as shown.

Then, the upper die 50 comes down and the blank holder 12
After the material 60 is clamped between and, the material 60 is molded between it and the lower die 59.

However, when the material 60 is clamped, a large impact sound is emitted. Therefore, in accordance with the lowering of the upper die 50, the solenoid valve 26 is switched to the F side, the oil in the pilot operation port 23 of the logic valve 17 is discharged to the tank 13, and the logic valve 17 is adjusted by the stroke limiter 63. Open to open
35 is switched to the D side and the upper mold is controlled by the control device 52 which inputs the detection signal 53 from the rotary encoder 52.
The position immediately before 50 hits the material 60 is detected, the servo valve 36 is adjusted to the C side for the required time, and the hydraulic cushion cylinders 2, 3
The pressure oil in the lower oil chambers 31, 32 of the oil tank 13 is passed through the flow passages 34, 37.
The pressure oil of the pump 14 through the flow path 20 and the upper oil chambers 21, 2
2, and the blank holder 12 is lowered.

At this time, as shown in FIG. 2, the amount of drained oil is adjusted so that the descending speed of the upper mold 50 when the upper mold 50 comes into contact with the material 60 and the descending speed of the blank holder 12 become substantially equal. It is controlled by the servo valve 36. As a result, the material 60 is gently clamped by the upper die 50 and the blank holder 12 and almost no impact noise can be generated.

After the above clamp, the solenoid valve 26 is switched to the F side to close the logic valve 17 so that the oil in the tank 13 is sucked into the upper oil chambers 21 and 22 through the flow paths 29 and 20. As the mold 50 descends, the cushion pad 11 is pushed down via the blank holder 12, and the pressing force is generated by the compression operation of the lower oil chambers 31, 32 of the hydraulic cushion cylinders 2, 3. At this time, the servo valve 36 is adjusted to the B side so as to return the oil in the lower oil chambers 31, 32 to the tank 13 while squeezing the oil through the flow paths 34, 37, and the return amount is controlled by the control device 57. By controlling with the signal 58, as shown in FIG. 3, adjustment according to the setting signal 56 by the setting device 55 so that the holding force required by the material such as the material 60, size, and drawing depth can be obtained ( In the figure, it is possible to gradually attenuate). At this time, the detection signals 45 and 46 from the pressure sensors 48 and 49 are transmitted to the control device 57.
Is fed back to and reliable control is performed.

Next, when the upper die 50 reaches the lower limit position where the operation changes from descending to ascending, that position is set to the rotary encoder.
The detection signal 53 from 52 is detected by the control device 57, and the control signal 58 from the control device 57 holds the servo valve 36 in the closed state shown in FIG. 1 for a required time.

As a result, the blank holder 12 temporarily stops its operation (locking operation) at the lowest limit position, but during this period, the upper mold 50 has started to rise, so
Will be demolded from the molded material 60.

Subsequently, the switching valve 35 is switched to the E side and the servo valve 11 is adjusted to the C side to discharge the oil from the upper oil chambers 21 and 22 and the accumulator 42.
Although the blank holder 12 is also raised by the pressure of, the blank holder 12 is also made to coincide with the rise of the upper die 50 gently as shown in FIG. 2 so that the blank holder 12 does not collide with the material 60 and the upper die 50 at this time. The rising speed is adjusted by the amount of oil discharged from the servo valve 36.

Also, when the blank holder 12 reaches the upper limit and returns to the initial posture, a collision noise is generated by hitting a stopper (not shown) at the upper limit. Therefore, the position immediately before the upper limit is detected by the control device 57 so that a detection signal from a limit switch or the like can be input, the servo valve 36 is adjusted to the B side by the control signal 57, and the return side of the upper oil chamber 14 is returned. As shown in FIG. 2, the upper limit stopper is adjusted slowly so that the servo valve 36 is closed and stopped at the upper limit position.

According to the above, by adjusting the servo valve 36, it is possible to adjust the pressing force of the cushion hydraulic cylinders 2 and 3 and prevent the generation of impact noise during press work, and to increase the rising speed of the blank holder by the hydraulic lift cylinder 4. You can

It should be noted that the present invention is not limited to the above-described embodiment, and a plurality of hydraulic cushion cylinders may be provided to allow the load received by the hydraulic cushion cylinders to be arbitrarily distributed, and within the scope not departing from the gist of the present invention. It goes without saying that various changes can be made in.

[Effects of the Invention] As described above, according to the die cushion device of the press machine of the present invention, since the blank holder is supported by the hydraulic cushion cylinder and the hydraulic lift cylinder, the blank holder can be made smaller than the conventional air cylinder, and the servo can be improved. By adjusting the valve, the pressing force of the hydraulic cushion cylinder can be adjusted freely, and by adjusting the servo valve so that the relative movement speed of the blank holder with respect to the upper mold is slow, noise during press work can be reduced. It is possible to significantly reduce the occurrence of the above-mentioned phenomenon, and it is possible to obtain an excellent effect that the rising speed of the blank holder can be increased by the hydraulic lifting cylinder.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of the present invention, FIG. 2 is a diagram showing a relationship between relative movement speeds of an upper mold and a blank holder according to the present invention, and FIG. 3 shows an example of control of a pressing force. Diagram, No. 4
The figure is an illustration of a conventional example. In the figure, 2 and 3 are hydraulic cushion cylinders, 4 are hydraulic lift cylinders, 11 is a cushion pad, 12 is a blank holder,
14 is a pump, 21 and 22 are upper oil chambers, 31 and 32 are lower oil chambers, 33 and 3
4 is a flow path, 35 is a switching valve, 36 is a servo valve, 40 is a lower oil chamber, 4
2 is an accumulator, 50 is an upper die, 51 is a press drive device, 52 is a rotary encoder, 53 is a detection signal, 55 is a setting device, 56 is a setting signal, 57 is a control device, 58 is a control signal, 59
Indicates a lower mold, and 60 indicates a material.

Claims (1)

[Claims] 1. A die cushion device for a press machine, comprising: an upper mold that can move up and down and a lower mold that does not move up and down, and a blank holder that can move up and down to clamp a material between the upper mold and the lower mold. A blank holder is supported by a hydraulic cushion cylinder and a hydraulic lift cylinder so as to be able to move up and down, and a flow path for supplying oil is connected to each of the upper and lower oil chambers of the hydraulic lift cushion cylinder, and a vertical movement is performed by a switching valve and a servo valve. A position detector for connecting a flow path for discharging oil by switching between the partial oil chambers, for connecting a flow path for supplying and discharging oil to the lower oil chamber of the hydraulic pressure rising cylinder, and for detecting the position of the upper die. A control device is provided for sending a control signal for adjusting a flow rate to the servo valve based on a setting signal from a setting device for inputting a detection signal from the setting tool and setting a relationship between the upper die position and the pressing force. Press machine of the die cushion device that.