JPH03198925A - Method for pressing panel member - Google Patents

Abstract

PURPOSE:To smoothly displace a step part and to secure formability by arranging the step part of a panel member obtained by butt-welding plates different in thickness on the opposite side of a female die and press-forming the step part under hydraulic pressure in the course of a pressing stage. CONSTITUTION:The step part 11 of a blank W is pressed under hydraulic pressure of a hydraulic pressure room 8 and since the step part 11 always comes in contact with pressurized fluid in a hydraulic room 8 in the course of the pressing stage, the blank W can be displaced smoothly without receiving large frictional resistance and since uniform pressurized fluid pressure is exerted on both sides of the step part 11, desired formability is secured to the blank W.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a press working method for panel members, and more specifically, to a method for press working panel members, and more specifically, a method for forming panel members having different thicknesses integrally by butt welding. The present invention relates to a method for press-forming a panel member, which allows the panel member to be press-formed smoothly.

(Prior Art) In recent years, there has been a need to press-form a panel member formed by butt welding plate materials of different thicknesses into a desired shape depending on the part where the panel member will be used. There is.

For example, in panel members for forming the body or door of a vehicle, from the viewpoint of reducing the weight of the vehicle, for example, the laser welding method disclosed in Japanese Patent Application Laid-Open No. 61-46389, etc. is used. By butt welding a plurality of plate materials with different thicknesses, a panel member whose thickness is partially reduced is manufactured, and the panel member thus formed is suitable for the part of the vehicle in which the panel member is used. It is necessary to mold it into the desired shape.

(Problem to be Solved by the Invention) However, when a panel member whose plate thickness is partially reduced in this way is press-formed using a conventional mechanical press machine, the stepped portion formed at the butt weld part When the member is displaced due to elongation deformation, a relatively large frictional resistance is generated between the stepped portion and the mold, and as a result, there is a possibility that elongation deformation of the panel member may be hindered.

Furthermore, since the wall thickness of the above-mentioned panel members differs between the butt-welded parts, there is a problem that the pressurizing force in the thin-walled parts is lower than that in the thick-walled parts, making it impossible to obtain the desired formability. Ta. In order to prevent this pressure from decreasing,
It would be possible to offset the end face of the mold that constitutes the press machine to correspond to the step formed in the butt weld, but for example, the thickness could be offset over the entire range where the step is displaced during pressing. If the outline of the mold is offset to correspond to the thick part, the pressure applied to the thin part will be transiently reduced in the offset part, and on the other hand, the offset will affect the entire range of displacement of the stepped part. If this is not done, the engagement between the stepped portion and the step formed at the edge of the offset portion may create excessive local stress in the panel member, which may cause the panel member to break. It has been extremely difficult to completely prevent the reduction in the pressing force by offsetting the contour of the mold.

(Object of the Invention) The present invention has been made in view of the above circumstances, and is intended to improve the formability of a panel member in a press working method for a panel member formed integrally by butt welding plate materials of different thicknesses. It is an object of the present invention to provide a press working method that can suitably secure the press working.

(Structure and operation of the invention) In order to achieve the above object, the present invention provides a press working method for a panel member in which plate materials of different thicknesses are integrally formed by butt welding. The step portion is placed in a press machine so as to face the side opposite to the female mold, and the step portion formed in the panel member is disposed using hydraulic pressure over at least the range in which the step portion formed in the panel member is displaced during the pressing process. A method for pressing a panel member is provided, which comprises press-molding the panel member.

According to the above configuration of the present invention, in the panel member, the step portion and the region of the panel member that extends near the step portion and where the step portion can be displaced during the pressing process are press-formed by hydraulic pressure. During the pressing process, the step portion can be smoothly displaced without being subjected to large frictional resistance, and substantially equal pressing force is applied to the thick and thin portions.

Therefore, the panel member does not have its elongation deformed restrained by the stepped portion or excessive local stress is generated in the panel member, and an even pressing force is not applied around the stepped portion. Therefore, its moldability is suitably ensured.

(Example) FIG. 1 is a schematic vertical sectional view partially showing a press machine for carrying out a press process according to the present invention. FIG. 2 is a partially enlarged sectional view showing the state around the butt welded portion of the blank shown in FIG. 1.

In FIG. 1, the press l includes an upper die 2 constituting a female die, a lower die 3 constituting a male die, and an upper blank holder 4.4 disposed on the side of the upper die 2. and a lower blank holder 5.5 arranged on the side of the lower die 3. The press l is shown in the final stage of the pressing process, in which the blank W is held between an upper blank holder 4.4 and a lower blank holder 5.5, and an upper die 2 and a lower die 3 are used to hold a blank W. The blank W is press-formed by applying strong pressure from above and below.

The upper die 2, the upper blank holder 3.3, and the lower blank holder are each moved up and down by a slide mechanism (not shown), and the lower die 3 is fixed to a frame (not shown).

The lower mold 3 is provided with a hydraulic pressure chamber 6 that opens upward in a substantially central portion thereof in the width direction, and the hydraulic pressure chamber 6 has side walls 6a and 6b.
and the upper surface of the piston 7, and accommodates pressurized fluid. The piston 7 is in sliding contact with the side walls 6a, 6b and is connected to a piston rod 9 of a fluid cylinder device 8, and by sliding in the vertical direction on the side walls 6a, 6b by the operation of the fluid cylinder device 8, The pressure of the pressurized fluid in the hydraulic chamber 6 is raised or lowered.

The lower mold 3 also has a sealing mechanism l0110 on the side of the hydraulic chamber 6.
It is equipped with a sealing mechanism 10. t.

By coming into close contact with the lower surface of the blank W, the hydraulic pressure chamber 6
The pressurized fluid inside is sealed.

Here, the blank W is a panel member manufactured by butt welding plate materials of different thicknesses, and the blank W is a panel member manufactured by butt welding plate materials of different thicknesses.
As shown in the figure, a stepped portion 11 is formed at the butt welded portion. The stepped portion 11 faces the hydraulic chamber 6 and is hydraulically pressed by pressurized fluid within the hydraulic chamber 6 . The width of the hydraulic chamber 8 is set to be larger than the width at which the stepped portion 11 is displaced due to the elongation deformation of the blank W that occurs during the pressing process. 8 facing the pressurized fluid.

FIGS. 3a, 3b, and 3c are explanatory diagrams showing step-by-step the pressing method using the press machine I.

As shown in FIG. 3a, at the beginning of the pressing process, the upper die 2 and the upper blank holder 4.4 are retracted upward.

Upper blank holder 4.4 and lower blank holder 5.
When the blank W is inserted between the upper blank holder 4 and the lower blank, the upper blank holder 4.4 is lowered by the slide mechanism of the press l, and the blank W is inserted between the upper blank holder 4 and the lower blank. and the holder 5 (Fig. 3b).

Next, the upper die 2, upper blank holder 4.4, and lower blank holder 5.5 are all lowered by the slide mechanism, the lower surface of the blank W is strongly pressed against the upper end surface of the lower die 3, and the blank W is It is deformed under pressure by the upper end surface of the lower die 2 (Fig. 3c).

At this time, the stepped portion 11 of the blank W faces the pressurized fluid in the hydraulic pressure chamber 8, and the pressurized fluid pressure in the hydraulic chamber is adjusted to correspond to the surface pressure on the upper end surface of the lower die 3. Since the pressure is increased by the cylinder device 8, the blank W is pressurized and deformed upward by the surface pressure on the upper end surface of the lower mold 3 and the surface pressure due to the pressurized fluid.

Further, the upper mold 2 is lowered relative to the upper blank holder 4.4 and the lower blank holder 5.5, and the upper mold 2 cooperates with the lower mold 3 to form the upper blank holder 4.4 and the lower blank holder 5.5, as shown in FIG. , pressurize and deform the blank W into the final shape.

During the pressurized deformation of the blank W, the stepped portion 11 is displaced laterally during the pressing process due to partial elongation deformation of the blank W, etc., but the stepped portion 11 faces the hydraulic chamber 8. Therefore, the displacement can be performed smoothly without experiencing large frictional resistance, and the pressurized fluid pressure is applied substantially equally to both the thick and thin portions extending on both sides of the stepped portion 11. Therefore, it is possible to avoid a local decrease in the pressurizing force.

In this way, in the above embodiment, the stepped portion 11 of the blank W is hydraulically pressed by the hydraulic pressure of the hydraulic pressure chamber 8,
Since the stepped portion 11 always faces the pressurized fluid in the hydraulic chamber 8 during the pressing process, the blank W is not subjected to large frictional resistance and is therefore prevented from being partially stretched and deformed. Furthermore, since substantially equal pressurized fluid pressure is applied to the portions of the blank W located on both sides of the stepped portion 11, desired formability of the blank W is ensured.

In the above embodiment, hydraulic pressing is performed partially over the movable width of the stepped portion 11, but hydraulic pressing may be performed over the entire width of the blank W.

〔Effect of the invention〕

According to the above configuration of the present invention, in a press working method for a panel member formed integrally by butt welding plate materials of different thicknesses, a press working method that can suitably ensure formability of the panel member is provided. It becomes possible to provide

[Brief explanation of drawings]

FIG. 1 is a schematic vertical cross-sectional view partially showing a press machine for implementing the press process method according to the present invention. FIG. 2 is a partially enlarged sectional view showing the state around the butt welded portion of the blank shown in FIG. 1. FIGS. 3a, 3b, and 3c are explanatory diagrams showing step-by-step the pressing method using the press shown in FIG. 1. FIG. l-Fist press machine, 2...Upper die, 3...Lower die, 4...Upper blank holder, 5...Lower blank holder, 6...Hydraulic pressure chamber, 7...Fist piston , 8 ・ 9 ・ l Oφ p W 轡・Fluid cylinder device, ・Piston rod, ・Liquid seal mechanism, ・Stepped portion, ・Blank, Fig. 3a, Fig. 1, Fig. 3b, Fig.

Claims (1)

[Claims] In a method of pressing a panel member formed integrally by butt welding plate materials of different thicknesses, the stepped portion formed in the panel member faces the side opposite to the female die. A panel characterized in that the panel member is placed in a press machine as shown in FIG. Pressing method for parts