JPH05212463A - Device for forming metal sheet by using hydraulic pressure with metal die - Google Patents

Abstract

PURPOSE:To enable forming of materials with low formability by supplying liquid which is a pressure medium; performing a hydraulic forming; pushing a male die, which is provided with a means to prevent the leak of the pressure medium, into a lower die after discharging the liquid and performing the die forming. CONSTITUTION:A thin metal plate, being a material for a press work, is fixed at the edge part by means of an upper blank holder 3 and a lower blank holder 4, a hydraulic pressure is actuated from an entrance provided in the holder 3 and the hydraulic forming is performed. The male die 6 is provided with an O-ring 7, and there is no leak of the hydraulic pressure from the die 6. After the liquid is discharged, forming is performed by lowering the male die 6, and finally by holding the material between the male die 6 and the female die 5, the material is formed with the dies. Thus, forming of the materials having a low formability by means of a conventional metal die method is made possible. Also, the shapeability of a formed article, which is a problem with a conventional hydraulic forming, is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for processing a blank material such as a thin metal plate to obtain automobile parts, electric parts, etc.
The present invention relates to a molding device that uses both hydraulic pressure and a mold.

[0002]

2. Description of the Related Art Conventionally, a press forming apparatus for a thin metal plate using a pair of upper and lower molds has been widely used as a known technique. Further, regarding a hydraulic forming device, Japanese Patent Application Laid-Open No. 48-43
59, a known technique as disclosed in JP-A-48-57881. However, for low-formability materials such as high-strength steel plates and aluminum, it is difficult to obtain the target molded product with the conventional press molding machine that is based on the premise of molding with a metal mold, while with conventional hydraulic molding machines. However, it has been impossible to obtain a molded product having a desired shape and dimension accuracy.

[0003]

SUMMARY OF THE INVENTION The present invention facilitates the molding of low-formability materials such as aluminum and high-strength steel sheets, which were difficult to form by the conventional molding method using a die, and also uses conventional hydraulic forming. It is an object of the present invention to provide a new molding apparatus for realizing a new molding method that improves the shape of a molded product in question.

[0004]

The present invention has been made by research to solve the problems of the above-mentioned prior art. In the present invention, in the first step, while fixing the periphery of the material by the upper mold wrinkle holding mold and the lower mold,
A liquid, which is a pressure medium, is fed from the punch side of the upper die to perform hydraulic forming, and in a second step, the end portion of the hydraulically formed material is fixed by a wrinkle holding die and a lower die of the upper die. However, after the liquid is discharged, or while being discharged, the material is pushed downward by the punch of the upper mold and brought into close contact with the lower surface of the molding lower mold, thereby making it possible to perform mold molding. .. For this reason, this molding device has an inner slide having a male mold equipped with an O-ring or a piston packing for preventing the leakage of liquid as a pressure medium, and an upper blank holder. It has a liquid inlet / outlet, a lower blank holder and a female die, and a hydraulic device to control the liquid pressure load pressure, load speed, and liquid medium in / out. Is characterized by.

[0005]

With the above-mentioned structure, the present invention eliminates the drawbacks of hydraulic forming and die forming, realizes a forming method that makes the best use of the advantages of both, and has a low formability of high-strength steel sheets, aluminum, etc. Facilitates molding of material. The molding mechanism is explained below.

The first problem in press molding is breakage. In the usual die forming, the point where the strain is concentrated is mainly determined by the target shape, and especially in the case of high-strength steel sheets and low-ductility materials such as aluminum, fracture occurs at such places and molding failure occurs. It will be possible. In the example shown in FIG. 1, the fracture occurs at the punch shoulder portion A. On the other hand, in hydraulic forming, since there is no frictional force, breakage occurs at the portion B in FIG. In the present invention, as shown in FIG. 3, in the hydraulic forming of the first step, strain is developed in the C portion, and
In the second step shown in (1), strain is developed in the portion D to disperse the strain concentration points and uniformly deform the entire molded product, thereby improving the molding limit of the low ductility material such as high strength steel plate or aluminum.

The next problem is shape. Even if it can be molded without breaking, it cannot be a product unless the desired shape is obtained. In particular, a high-strength steel sheet has a high yield stress, and aluminum has a low Young's modulus, which makes it impossible to obtain a desired shape of a molded product due to springback after forming. From the viewpoint of the molding method, it is possible to eliminate such a shape defect by increasing the amount of deformation at the place where such a shape defect occurs. That is, the springback corresponds to the ratio of the amount of deformation given by processing and the amount of elastically recovered deformation, and the amount of elastically recovered deformation decreases as the amount of deformation by processing increases. However, for example, in the case of die molding shown in FIG. 1, the deformation amount of the E portion is at most several percent due to the frictional force between the punch and the material. On the other hand, in the present invention, in the first step shown in FIG. 3, it is possible to obtain a good shape of the molded product by sufficiently deforming the C portion where the deformation amount cannot be obtained by the usual die molding.

Further, since there is a limit to the hydraulic pressure that can be industrially applied in the conventional hydraulic molding, when it is necessary to obtain a molded product having a low radius of curvature as shown in F part of FIG. Can't get However, in the present invention, it is possible to obtain a molded product having such a low radius of curvature because the molding is performed in the second step.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a metal thin plate forming apparatus according to the present invention, which uses a hydraulic pressure and a mold together, will be described below with reference to FIGS. The press device shown in FIG. 6 is a double-action press, and is a male die 6 mounted on the lower end of the inner slide 2 and moved up and down, and an outer periphery of the male die 6 mounted on the lower end of the outer slide 1 and moved up and down. It has a blank holder 3, a lower blank holder 4 and a female die 5 arranged so as to face the blank holder 3. The metal thin plate, which is a press material, has its peripheral edge portion fixed by the upper blank holder 3 and the lower blank holder 4, and is hydraulically formed (first step) by the liquid flowing in through the inlet / outlet installed in the upper blank holder 3 or the male die 6. ). Further, in the hydraulic forming, the male die 6 has a piston packing 7 in order to prevent the liquid as the pressure medium from leaking from the gap between the male die 6 and the upper blank holder.

After that, the metal plate, which is a press material, has its peripheral portion fixed by the upper blank holder 3 and the lower blank holder 4, and after the liquid is discharged by the inlet / outlet installed in the upper blank holder 3 or the male die 6, or While the male die 6 descends while being molded,
Finally, it is molded by being sandwiched between the male mold 6 and the female mold 5 (second step). By connecting the hydraulic device shown in FIG. 7 to the press device shown in FIG. 6, the hydraulic forming in the first step and the discharge of the liquid after the hydraulic forming are controlled.

[0011]

INDUSTRIAL APPLICABILITY The present invention relates to a molding apparatus for processing a blank material such as a thin metal plate to obtain an automobile part, an electric part, etc. By using this apparatus, a molding method using a conventional mold is used. It is an epoch-making new molding device that can form difficult-to-form materials such as aluminum and high-strength steel plate, which were difficult, and can improve the shape of the molded product which is a problem in conventional hydraulic forming. .. Therefore, an extremely large effect is expected in the industry.

[Brief description of drawings]

FIG. 1 shows an example of die molding.

FIG. 2 shows an example of hydraulic forming.

FIG. 3 shows a first step of the present invention, hydraulic forming.

FIG. 4 shows a second step of the present invention, mold molding.

FIG. 5 shows an example of a molded product having a low radius of curvature.

FIG. 6 shows an embodiment of the press body of the device of the present invention.

FIG. 7 shows an embodiment of the hydraulic system of the device of the present invention.

[Explanation of symbols]

 1 Outer slide 2 Inner slide 3 Upper blank holder 4 Lower blank holder 5 Female type 6 Male type 7 Piston packing

Claims (1)

[Claims] 1. An apparatus for forming a thin metal plate, which comprises an inner slide having a male mold having an O-ring or a piston packing for preventing leakage of a liquid as a pressure medium, and an upper blank holder, and either of which is provided. It has a liquid inlet / outlet used for hydraulic loading, a lower blank holder and a female die, and also controls the hydraulic load pressure, load speed, and liquid medium inlet / outlet. A molding device that uses a hydraulic pressure and a mold together, characterized by having a hydraulic device.