JPH0829365B2 - 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
When it hits the stopper (not shown) in the raised upper limit, it emits a loud noise (metal sound), especially the upper mold i.
When the material hits the material d for the first time, a significant impact sound is emitted, 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. However, there is a problem that the clamping force is excessively increased on the material, which causes cracks and wrinkles in the material d.

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 cylinder so that the blank holder can be moved up and down, and a flow path equipped with a servo valve for supplying and discharging pressure oil is connected to the upper and lower oil chambers of the hydraulic cylinder. The detection signal from the position detector that detects the position of the position is input to send the control signal for adjusting the flow path 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 with a control device.

[Operation] Therefore, in the present invention, since the hydraulic cylinder is used, the device can be downsized as compared with the case where the conventional air cylinder is used, and the detection signal from the position detector indicating the position of the upper die is obtained. Based on this, the control device sends a control signal to the servo valve, and the servo valve controls the pressing force of the hydraulic cylinder by supplying and discharging pressure oil in the upper and lower oil chambers of the hydraulic cylinder, and also when lowering the upper mold. By operating the servo valve and lowering the blank holder, it is possible to prevent the generation of noise when the material is clamped by the upper mold.

[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.

A vertically oriented hydraulic cylinder 2, 3 is arranged on the lower surface of the fixed base 1, and a piston rod extending through the fixed base 1 upwardly through pistons 4, 5 fitted in the hydraulic cylinder 2, 3 so as to move up and down. Attach 6, 7 as a unit.

A cushion pad 8 is attached to the upper ends of the piston rods 6 and 7, and a blank holder 9 is attached on the cushion pad 8.

Upper oil chambers 10,11 and lower oil chambers 12,13 of hydraulic cylinders 2,3
The oil in the oil tank 14 is stored in the pump 15, filter 16, check valve 17, accumulator 18 capable of accumulating pressure inside, servo valve 19
So that the oil in the upper oil chambers 10, 11 and the lower oil chambers 12, 13 can be supplied through the flow paths 20, 20 and 22.
The oil is returned to the oil tank 14 via 21, 22, the servo valve 19 and the flow path 23.

A pressure sensor for individually detecting the oil pressures in the lower oil chamber 13 and the upper oil chamber 11 of the hydraulic cylinder 3 and inputting the detection signals 24 and 25 to the pressing force by calculating the deviation between the two. 27 and 28 are provided, and a detector such as a rotary encoder 31 that detects the rotational angle position of the press drive device 30 that moves up and down the upper die 29 (that is, the position of the upper die 29) is provided. A control device 36 for inputting the signal 32 and the deviation signal 33 from the comparator 26 as well as the setting signal 35 that sets the relationship between the pressing force and the rotational angle position from the setting device 34 is provided, and the control signal from the control device 36 The servo valve 19 is controlled by 37.

In the figure, 38 is a lower die fixed to the bolster plate, 39 is a material, and 40 and 41 are relief valves.

When the upper die 29 is raised, set the servo valve 19 to A
Then, the oil from the pump 15 is supplied to the lower oil chambers 12 and 13 to raise the blank holder 9 to the set upper limit position, and in this state the servo valve 19 is closed.

Then, the upper mold 29 comes down and the blank holder 9
After the material 39 is clamped between and, the material 39 is molded between it and the lower die 38.

However, when the material 39 is clamped, a large impact sound is emitted. Therefore, the upper mold 29 is made of a material by the control device 36 which inputs the detection signal 32 from the rotary encoder 31.
The position immediately before hitting 38 is detected, the servo valve 19 is adjusted to the B side for the required time, the pressure oil of the accumulator 18 is supplied to the upper oil chambers 10 and 11 via the flow paths 20 and 21, and the lower oil chamber 12 , 13 is returned to the oil tank 14 via the flow paths 22, 23, and the blank holder is lowered.

At this time, as shown in FIG. 2, the amount of oil supplied is controlled by the servo valve so that the descending speed of the upper mold 29 when the upper mold 29 comes into contact with the material 39 and the descending speed of the blank holder 9 become substantially equal.
Controlled by 19. As a result, the material 39 is gently clamped by the upper mold 29 and the blank holder 9 and almost no impact noise is generated.

After the clamp, the cushion pad 8 is pushed down through the blank holder 9 by the lowering of the upper mold 29, and the pressing force is generated by the compression operation of the lower oil chambers 12 and 13. At this time, the servo valve 19 is adjusted to the B side so as to return the oil in the lower oil chambers 12 and 13 to the oil tank 14 while squeezing the oil through the flow paths 22 and 23, and the return amount from the control device 36. By controlling with the control signal 37, as shown in FIG.
The pressing force can be adjusted (stepwise attenuated in the figure) according to the setting signal 35 by the setting device 34 so that the pressing force required by the material, size, drawing depth, etc. can be obtained. At this time, the detection signals 24, 25 from the pressure sensors 27, 28, that is, the comparators
The deviation signal 33 from 26 is fed back to the control device 36, and reliable control is performed.

Next, when the upper die 29 reaches the lower limit position where the operation changes from descending to ascending, that position is set to the rotary encoder.
The control signal 36 from the control signal 36 from the control device 36 is used to detect the detection signal 32 from the control signal 36, and the servo valve 19 is held in the closed state shown in FIG.

As a result, the blank holder 9 temporarily stops its operation (locking operation) at the lowermost position, but the upper die 29 starts to rise during this period, so that the upper die 29 moves upward.
Will be demolded from the molded material 39.

Then, adjust the servo valve 19 to the A side and adjust the blank holder 9
The blank holder 9 also causes the material 39 to rise.
Also, as shown in FIG. 2, the rising speed is adjusted by the amount of pressure oil supplied to the lower oil chambers 12 and 13 so as to gently match the rising of the upper mold 29 so as not to collide with the upper mold 29.

Also, when the blank holder 9 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. For this reason, the position immediately before the upper limit is detected by the control device 36 that inputs a detection signal such as a limit switch, the servo valve 19 is adjusted in advance to the B side by the control signal 37, and the pressure oil of the accumulator 18 is adjusted. 2 is supplied to the upper oil chambers 10 and 11, the upper limit stopper is adjusted so as to slowly come into contact with the upper oil chamber 10 and 11, and then the servo valve 19 is closed and stopped at the upper limit position.

According to the above, by adjusting the servo valve 19, the lower oil chamber 1
It is possible to adjust the pressing force of 2, 13 and prevent the generation of impact noise during press work.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the present invention.

[Advantages of the Invention] As described above, according to the apparatus of the press machine of the present invention, since it is supported only by the hydraulic cylinder of the blank holder, it can be made smaller than the conventional air cylinder, and the hydraulic pressure can be adjusted by adjusting the servo valve. The pressing force of the 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 generation during press work can be significantly reduced. It is possible to exert an excellent effect.

[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. 2, 3 are hydraulic cylinders, 8 is a cushion pad, 9 is a blank holder, 10 and 11 are upper oil chambers, 12 and 13 are lower oil chambers, 15 is a pump, 19 is a servo valve, 20, 21, 22, 23 are Flow path, 29 is upper die, 30 is press drive device, 31 is rotary encoder,
32 is a detection signal, 34 is a setting device, 35 is a setting signal, 36 is a control device, 37 is a control signal, 38 is a lower die, and 39 is 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. The blank holder is supported by a hydraulic cylinder so that it can move up and down, and a flow path equipped with a servo valve for supplying and discharging pressure oil is connected to the upper and lower oil chambers of the hydraulic cylinder, and a position detector that detects the position of the upper mold is used. A control device for sending a control signal for adjusting the flow path to the servo valve based on a setting signal from a setting device for inputting the detection signal of the above and setting the relationship between the upper die position and the pressing force. Die cushion device for press machines.