JPH0747196Y2 - Die cushion device of press machine - Google Patents

Description

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

2. Description of the Related Art Conventionally, in, for example, a single-acting press, a blank is placed on a punch, and its peripheral portion is supported by a pressure ring, and this pressure ring is supported by a pressure pad via a cushion pin. Further, the pressure pad is connected to a pneumatic cylinder, and it is considered that the pressure ring can be followed within a certain range when the slide, that is, the lowering and raising of the die, and the press working can be performed well. However, according to this structure, the blank after press working, that is, the product rises following the rise of the die, so that the product and the mold may be damaged. As a solution to this drawback, the one disclosed in Japanese Utility Model Laid-Open No. 61-205619 has already been proposed. In this type, a rod-shaped body is hung on the lower surface of the pressure pad, a piston portion is formed under the rod-shaped body, and a cylinder portion is arranged to provide a hydraulic cylinder for pressure pad locking. The upper hydraulic chamber and the lower hydraulic chamber are connected by a pipe having a logic valve. In this configuration, the die starts to rise after the pressure pad has dropped to the bottom dead center.At this time, the logic valve has a check function, and the rod is temporarily locked to stop the pressure pad from following. It prevented the occurrence of scratches on blanks, molds, etc.

According to the above-described conventional configuration, the pressure pad is locked by the hydraulic cylinder via the rod-shaped body at the bottom dead center, but at this time, the pneumatic cylinder exerts a force in the upward direction, and As the body stretches slightly, this amount of stretch changes depending on the cushioning capacity, that is, the air pressure. Therefore, when the product is taken out in such a stretched state, it cannot be taken out at an accurate position, that is, at a fixed position, and there has been a problem that an automatic carrying press causes a carrying error.

Then, this invention aims at providing the die cushion apparatus of a press machine which can solve the said subject.

Means for Solving the Problems In order to solve the above problems, a die cushion device of a press according to the present invention has a pressure pad provided on its upper surface with a pressure ring for holding a blank peripheral portion between the pressure pad and the pressure pad. In a die cushion device of a press machine having a pneumatic cylinder for urging the pressure pad upward, a lift amount detector for detecting the lift amount from the reference position of the pressure pad is provided on the pressure pad, and the pressure pad is connected via a piston rod. A hydraulic cylinder having a piston that interlocks with each other is provided, and the hydraulic chambers on both sides of this hydraulic cylinder are communicated with each other by a locking hydraulic pipe with a logic valve interposed between the hydraulic chambers. If a hydraulic pipe for oil amount control with a servo valve for controlling the supply / discharge amount is provided, Anyway,
A control device for controlling the servo valve in response to a signal from the lift amount detector is provided.

Action In the above configuration, at the bottom dead center position of the pressure pad,
When the logic valve is fixed and the pressure pad is locked by the hydraulic cylinder, if the pressure pad rises from the reference position, that is, the product take-out position due to the piston rod stretching due to heat, etc. The lift amount detector accurately detects and the servo valve is controlled by the signal from the lift amount detector to lower the piston of the hydraulic cylinder. Therefore, since the product is always taken out at a fixed position, it is possible to prevent the occurrence of conveyance error.

Embodiment An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, reference numeral 1 is a slide in a press machine, and a die 2 is fixed to the lower surface thereof. A press bed 3 is arranged below the slide 1, and a punch 6 is fixed on the press bed 3 via a bolster 4 and a holder 5. In addition, a pressure pad 7 is arranged in the press bed 3 so as to be able to move up and down via a pneumatic cylinder 8, and a plurality of cushion pins 9 are erected on the upper surface thereof so as to pass through the bolster 4 and the holder 5. With
At the upper ends of these cushion pins 9, a pressure ring 11 is provided which is located around the punch 6 and presses and holds the peripheral edge of the blank 10 in cooperation with the die 2. The pressure pad 7 includes a rooke hydraulic cylinder 12 for temporarily locking the movement of the pressure pad 7 at the bottom dead center position.
The hydraulic cylinder 12 is equipped with a mechanism for preventing the pressure pad 7 from rising by the pneumatic cylinder 8 when locked. That is, the cylinder body 13 of the hydraulic cylinder 12 is fixed to the lower surface of the support base 16 of the pneumatic cylinder 8, and the piston 14
The upper end of the piston rod 15 having the above is inserted into the support pad 16 and the pneumatic cylinder 8 and connected to the pressure pad 7, and the pressure pad 7 is provided in the press bed 3.
A lift amount detector (hereinafter, simply referred to as a detector) 17 for detecting the lift amount is arranged. This detector 17
For example, the rack body 18 hangs from the lower edge of the pressure pad 7, and an encoder 20 having a pinion 19 meshing with the rack body 18 to detect the position of the pressure pad 7. The upper and lower hydraulic chambers 21A and 21B of the hydraulic cylinder 12 are provided with a lock hydraulic pipe 23 in which a first logic valve 22 is interposed and an insertion in which second and third logic valves 24 and 25 are interposed. The hydraulic pump 27, the filter 28, and the accumulator 29 are connected to each other by the general-purpose hydraulic pipes 26, and are connected to each other by the hydraulic pipes 26, 26.
A pressure oil supply pipe 30 having, for example, is connected. Also,
The first to third logic valves 22, 2 are connected to the hydraulic pipes 23, 26, respectively.
First to third solenoid valves 31 to 33 for turning on / off, that is, locking or freeing the check functions of the valves 4 and 25 are provided. A pressure oil relief valve 34 is connected in the middle of the pressure oil supply pipe 30. When the first solenoid valve 31 is in the OFF state, the pilot pressure acts as it is and the first logic valve 22 is in the locked state, and in the ON state, the pilot pressure is released and the first logic valve 22 is in the free state in which it can be inserted. Become. Similarly, when the second and third solenoid valves 32 and 33 are off, the second and third logic valves 24 and 25 are in a locked state,
In the on state, it becomes a free state. Further, in the middle of the communication hydraulic pipe 26, the amount of oil (pressure oil supply / discharge amount)
Servo valve 35 for control is interposed and hydraulic pump
An oil amount control hydraulic pipe 38 having an accumulator 37 is connected. Further, the servo valve 35 is an encoder of the detector 17 that detects the lift amount of the pressure pad 7.
Based on the signal from 20, the control is performed via the control device 39. That is, when the pressure pad 7 is lifted from the reference position when the pressure pad 7 is locked, the servo valve 35 is switched to the III position via the control device 39 by the signal from the encoder 20, and the accumulator 3 is operated.
When pressure oil is supplied to the upper hydraulic chamber 21A from 7 and the pressure pad 7 is lowered from the reference position, the servo valve 35 is switched to the I position via the control device 39 by the signal from the encoder 20. Then, the pressure oil in the upper hydraulic chamber 21A is returned to the tank side.

Next, the operation of the above configuration will be described.

Before the slide 1 starts descending and the die 2 comes into contact with the blank 10, the first solenoid valve 31 is excited and the first logic valve 31 is excited.
22 is made free, and second and third solenoid valves 32, 33
Is de-excited and the second and third logic valves 24 and 25 are locked. In this state, the die 2 descends, and the blank 10 is sandwiched between the die 2 and the pressure ring 11, and press working is performed. At this time, the pressure pad 7 descends and the piston
As the cylinder 14 descends in the cylinder body 13, the oil in the cylinder body 13 is transferred to the lower pressure oil chamber 21 via the locking hydraulic pipe 23.
B flows into the upper pressure oil chamber 21A. Then, when the pressure pad 7 is lowered to the bottom dead center, the first solenoid valve 31 is de-energized and the first logic valve 22 is locked. Therefore,
As the die 2 rises, the pressure pad 7 tries to rise due to the force of the pneumatic cylinder 8, but the hydraulic cylinder 12 or the pressure pad 7 is locked due to the interruption of the locking hydraulic pipe 23. Then, at this time, as described above, the lift amount from the reference position of the pressure pad 7 is detected by the signal from the encoder 20 of the detector 17, and the lift amount is eliminated or is always constant. To the servo valve 35 via the control device 39
Is controlled. For example, when the pressure pad 7 is floating, pressure oil is supplied to the upper hydraulic chamber 21A.
In this case, the pressure oil in the lower hydraulic chamber 21B is returned from the relief valve 34 to the oil tank. On the contrary, when the pressure pad 7 is lowered, pressure oil is discharged from the upper hydraulic chamber 21A and pressure oil is supplied to the lower hydraulic chamber 21B from the accumulator 29 on the pressure oil supply pipe 30 side. It As described above, when the pressure pad 7 is locked, the lift amount is controlled so as to disappear or become constant, so that the product, which is a blank after processing, is taken out at a constant position. Then, after the product is taken out by the product holder, the second and third solenoid valves 32, 33 are excited and the second,
The third logic valve 24,25 is freed. Therefore,
The pressure pad 7 is lifted by the force of the pneumatic cylinder 8 and then pressed again.

When the piston rod 15 of the hydraulic cylinder 12 is inserted through the pneumatic cylinder 8 as in the above configuration, the piston rod 15 itself extends due to heat, and the pressure pad 7 rises. The lifting prevention mechanism is effective.

Effect of the Invention According to the configuration of the present invention as described above, when the pressure pad is lifted due to the extension of the piston rod due to heat, the lift amount of the pressure pad locked by the hydraulic cylinder is detected by the lift amount detector. To accurately detect
Since it can be controlled via the lift amount detector and servo valve, the product take-out position after pressing can always be kept at a fixed position, thus preventing the occurrence of product transfer mistakes in the automatic press machine. You can

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a cross section of a device and a hydraulic circuit in an embodiment of the cushion lock device of the present invention. 1 ... Slide, 2 ... Die, 7 ... Pressure pad, 8 ... Pneumatic cylinder, 10 ... Blank, 11 ... Pressure ring, 12 ... Hydraulic cylinder, 14 ... Piston, 15 ... Piston rod, 17 …… Lifting amount detector,
18 …… rack body, 19 …… pinion, 20 …… encoder,
21A, 21B …… hydraulic chamber, 22 …… first logic valve, 23 …… lock hydraulic piping, 24,25 …… second and third logic valve, 26
...... Communication hydraulic piping, 29 …… Accumulator, 30 …… Pressure oil supply piping, 31 …… First solenoid valve, 32,33 …… Second, third
Solenoid valve, 35 ... Servo valve, 37 ... Accumulator, 38 ...
... hydraulic piping for oil quantity control, 39 ... control device.

Claims (1)

[Scope of utility model registration request] 1. A die cushion device for a press, comprising: a pressure pad having an upper surface provided with a pressure ring for holding a blank peripheral edge between the die and the die; and a pneumatic cylinder for urging the pressure pad upward.
A lift amount detector that detects the lift amount of the pressure pad from the reference position is provided on the pressure pad, and a hydraulic cylinder having a piston that interlocks with the piston rod is provided on the pressure pad. Oil pressure control hydraulics in which the chambers are connected by a hydraulic lock pipe with a logic valve in the middle, and a servo valve for controlling the hydraulic oil supply / discharge amount is interposed in one hydraulic chamber of the hydraulic cylinder. A die cushion device for a press machine, which is provided with a pipe and is provided with a control device for controlling the servo valve according to a signal from the lift amount detector.