JPH08155557A - Hydraulic pressure counter forming device - Google Patents

Abstract

PURPOSE: To produce a good product not causing breakage and wrinkle by controlling reverse bulging rate in suitable range and increasing drawing ratio by means of effectively utilizing reverse bulging rate when variance in material of blank and lubricating condition are varied. CONSTITUTION: A die 4 is arranged on a cylindrical body 3 arranged on the upper part 1a of a frame 1 and forming hydraulic pressure chamber 2, a blank holder device 7 to hold the periphery of blank W and a cylinder device 6 for press to drive a punch 5 for press are provided on the crown part 1b of the frame. The reverse bulging detector to detect the reverse bulging rate β of blank W at driving the punch 6 for press is provided, further, a controller 9 to control a hydraulic pressure in the hydraulic pressure chamber 2 based on the detected value of the reverse bulging rate detector 8 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an opposed hydraulic forming apparatus for drawing blanks such as thin plates to form automobile parts, electric parts, aircraft parts and the like.

[0002]

2. Description of the Related Art In an opposed hydraulic press machine, a material causes reverse bulging in a gap between a punch and a blank holder. This reverse bulging is caused by, for example, the Japan Society of Mechanical Engineers (Part 3 (necessary) 30). Volume 214 (June 1964) Page 724-
Page 725, 6. In one aspect of hydraulic action,
"The following three points have already been pointed out as guidelines for demonstrating the characteristics of this method and obtaining good drawing results." (3) item "Give initial pressure to the pressure chamber of the die." , "So-called" backward extension "of the material, and expecting to improve the drawing ratio". In addition, 57
Japanese Patent No. 3622 proposes that the blank holder is provided with a certain curved portion in order to make the amount of reverse protrusion constant. The already proposed Japanese Patent Publication Sho 57-780
The same is proposed for the molding method of Japanese Patent No.

[0003]

However, in the case of performing reverse bulging for the purpose of improving the drawing ratio as described above, the product is first molded, the presence or absence of breakage and the condition of wrinkles are observed, and the wrinkle presser for the stroke is suppressed. Although it is necessary to set the force and the generated hydraulic pressure, the quality of the product will be good or bad even with the same setting due to the variation of the material and the lubrication state. Also, like the latter, if the curved portion is formed in the blank holder,
If the above various conditions are changed, the effect of reverse bulging may not occur.

The present invention solves the above-mentioned problems, improves the drawing ratio by effectively utilizing the reverse bulging, and can stably produce a good product without breakage or wrinkles. An object is to provide a molding device.

[0005]

In order to solve the above problems, an opposed hydraulic forming apparatus of the present invention has a die arranged on one end of a frame to form a hydraulic chamber, and a die is disposed on the cylindrical body. On the other end of the frame, a blank holder device that holds the peripheral edge of the blank material on the die is provided, and a press cylinder device that drives the press punch to push the blank material into the hydraulic chamber is provided. A counter-bulging amount detector that detects the back-bulging amount generated in the blank material by the initial pressure when the blank material is pushed into the hydraulic chamber by the punch is provided.
A control device for controlling the hydraulic pressure in the hydraulic chamber based on the detection value of the reverse bulging amount detector is provided.

[0006]

According to the above construction, by controlling the hydraulic pressure in the hydraulic chamber based on the detection value of the reverse bulging amount detector, variations in the blank material and the lubrication state may change. However, since the amount of reverse bulging can be kept constant, it is possible to always effectively utilize the reverse bulging, improve the drawing ratio, and produce a good product without breakage or wrinkling.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an opposed hydraulic forming apparatus according to the present invention will be described below with reference to the drawings. A cylinder 3 that forms the hydraulic chamber 2 is installed on the bed portion 1 a of the frame 1, and a die 4 is provided so as to face the upper opening of the cylinder 3. On the other hand, on the crown portion 1b of the frame 1, a press cylinder device 6 that supports a press punch 5 so as to be vertically movable.
And a blank holder device 7 for pressing and holding the peripheral edge of the blank material W on the die 4 via the hold member 7B by the hold cylinder device 7A.

The holding member 7B of the blank holder device 7 is formed with rounded portions 7a having a small diameter at the corners of the bottom surface and the inner surface in order to smoothly perform the reverse projection, and the reverse tension of the blank material W is provided on the inner surface portion. A plurality of anti-bulging amount detectors 8 for detecting the output amount β are arranged, and the detected value is the control device 9
Is configured to be input to. The non-bulging amount detector 8 is preferably a non-contact type such as a laser type displacement gauge, but may be a contact type strain displacement gauge. A liquid supply pipe 11 for supplying a liquid to the hydraulic chamber 2 and a liquid discharge pipe 13 for controlling the hydraulic pressure of the hydraulic chamber 2 through a relief valve 12 are connected to the hydraulic chamber 2. A pressure detector 14 for detecting the hydraulic pressure in the hydraulic chamber 2 is provided. Then, the relief valve 12 is operated by the operation signal output from the control device 9 based on the detection signal from the reverse bulging amount detector 8 and the detection signal from the pressure detector 14, and the liquid in the hydraulic chamber 2 is operated. The pressure is controlled so that the amount of reverse bulging β of the blank material W becomes constant.

The press cylinder device 6 is supplied with a predetermined hydraulic pressure from the press hydraulic pressure supply device 15 in response to a signal from the control device 9 to activate the press punch 5, and the hold cylinder device 7A has a control device. A hydraulic pressure of a predetermined pressure is supplied from the holding hydraulic pressure supply device 16 by the signal 9 to hold the blank material W at an appropriate pressure.

In the above structure, when the blank material W is placed on the die 4 and the blank holder device 7 presses and holds the peripheral edge of the blank material W, the press hydraulic pressure supply device 15 moves to the press cylinder device 6. Hydraulic pressure is supplied to lower the punch 5 for pressing, and the blank material W is pushed into the hydraulic chamber 2 side. Then, due to the action of the initial pressure of the hydraulic chamber 2, the blank material W is reversely bulged at the periphery of the pushing portion of the punch 5 for pressurization, and the backlashing amount β is detected by the backlashing amount detector 8 and controlled. Input to the device 9. The control device 9 compares this detected value with the reference amount of reverse bulge input from the presetter 17, and if the amount of reverse bulge β is larger than the reference amount of bulge, an open signal is sent to the release valve 12. Is output to decrease the hydraulic pressure in the pressure chamber 2, and when the reverse bulge amount β is smaller than the reference reverse bulge amount, a close signal is output to the release valve 12 to output the hydraulic pressure in the pressure chamber 2. By increasing the pressure by reducing the decompression amount of
The amount of reverse bulge β is controlled to be within the appropriate range. Further, the punch 5 for pressing is pushed into the hydraulic chamber 2 and the press working is continued, and the process is finished at the bottom dead center.

According to the above-described embodiment, by controlling the hydraulic pressure of the hydraulic chamber 2 based on the detection value of the reverse bulging amount detector 8, the variation of the raw material of the blank material W and the lubrication state are changed. Even if there are cases, the amount of reverse protrusion β for each blank material W
Can be kept within an appropriate range, so that reverse drawing can be effectively used to improve the drawing ratio, and a good product without breakage or wrinkles can be stably produced.

[0012]

As described above, according to the opposed hydraulic forming apparatus of the present invention, even if there is a variation in the material of the blank material or the lubrication state is changed, the detection value of the reverse bulge amount detector is detected. By controlling the hydraulic pressure in the hydraulic chamber based on the above, the amount of reverse bulging can be kept constant for each blank material, so the reverse bulging is always effectively used to improve the drawing ratio and to prevent breakage and wrinkling. It is possible to stably produce good products without

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an opposed hydraulic forming apparatus according to the present invention.

[Explanation of symbols]

 W Blank material β Reverse overhang 1 Frame 2 Hydraulic chamber 3 Cylindrical body 4 Die 5 Press punch 6 Press cylinder device 7 Blank holder device 7A Hold cylinder device 7B Hold member 8 Reverse overhang detector 9 Control device 12 Relief valve 13 Liquid discharge pipe 14 Pressure detector

Claims (1)

[Claims] 1. A blank holder device for holding a peripheral edge of a blank material on the die is provided on the other end side of the frame, wherein the die is placed on a cylindrical body which is placed on one end side of the frame to form a hydraulic chamber. At the same time, a press cylinder device that drives the press punch to push the blank material into the hydraulic chamber is provided.When the blank material is pushed into the hydraulic chamber by the press punch, the reverse tension that occurs in the blank material due to the initial pressure Opposed hydraulic forming, characterized in that a reverse bulge amount detector for detecting the bulge amount is provided, and a control device for controlling the hydraulic pressure of the hydraulic chamber based on the detection value of the reverse bulge amount detector is provided. apparatus.