JP2001225114A - Hydraulic forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic forming method in which the generation of thickness deviation and deterioration of ductility are reduced and even parts having a complicated shape are easily formed by preventing generation of large work strain in a material before hydraulic forming. SOLUTION: In this hydraulic forming method, a prescribed part 4 is cut out from a folded or superposed metallic sheet 1 after seam-welding (3: seam welded parts) the edge parts of the prescribed part, or the edge parts of the prescribed part are seam-welded after cutting out, and then the hydraulic bulging work of the obtained base stock 4 is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydroforming method and, more particularly, to a hydroforming method which is preferably used when manufacturing parts having complicated shapes such as automobile parts.

[0002]

2. Description of the Related Art From the viewpoint of weight reduction of a vehicle body, a part (HF part) manufactured by hydroforming (HF) processing is beginning to be used for an undercarriage part of a vehicle such as a suspension arm and a structural part of a vehicle such as a frame. . HF
In processing, usually, a method is used in which a metal pipe such as an electric resistance welded steel pipe is used as a material, the metal pipe is placed in a mold having a predetermined shape, and a liquid is introduced into the pipe to apply an internal pressure. According to this method, the metal tube undergoes bulge deformation until the outer surface of the material follows the shape of the mold due to the internal pressure, and becomes an HF component having a predetermined outer shape.

[0003] However, the shape of automobile parts is V-shaped, T-shaped.
There are various types such as molds and horseshoe shapes, and the shapes of the molds correspond to these. On the other hand, since the metal tube is usually straight, the metal tube must be bent (pre-bend) before it is inserted into a bent mold such as a V-shaped or horseshoe-shaped mold.
Alternatively, a preform process is performed in which a press (prepress) process is performed to form a shape into a mold.

[0004] In HF processing, if the wall thickness accompanying the bulge deformation increases, it becomes difficult to secure the required strength of the parts. Therefore, the bulge portion is pressed with an internal pressure (pushing both ends of the pipe toward the center of the pipe axis). It is often done to suppress the thickness loss.

[0005]

SUMMARY OF THE INVENTION H using a metal tube as a material
In the F processing, the material is work-hardened at the stage of forming a metal plate into a tube. Also, in order to form a metal tube into an HF part having a complicated shape, preform processing is necessary. When the preform processing is added, uneven thickness occurs, work hardening increases, and the ductility of the material deteriorates. I do. When ductility deteriorates,
Since cracks occur in the material with a relatively small deformation amount, the processing amount (bulge deformation amount) in the HF processing cannot be made too large. In addition, if there is uneven thickness, the thin portion is preferentially deformed, and buckling or wrinkling occurs at the time of pushing the shaft, which tends to cause molding failure.

Therefore, in order to manufacture an HF part having a complicated shape, it is important to reduce uneven thickness of the material before HF processing and to secure ductility. In this regard,
Japanese Patent Application Laid-Open No. 10-175026 discloses a method in which the preform processing is performed by an expanded pipe bending method. But with this method,
Although uneven wall thickness can be reduced, ductility is degraded due to considerable work hardening.

Japanese Unexamined Patent Publication (Kokai) No. 64-34515 discloses a method of forming a concave-shaped preform in the vicinity of a projection forming part in the case of a T-shaped part. But,
In this method, the portion of the T-shaped portion on the side opposite to the protruding portion is increased in thickness when the shaft is pushed, and the shape instability is increased and buckling is likely to occur, so that the bulge deformation (in this case, the protruding height) can be increased. Can not.

Japanese Patent Application Laid-Open No. 10-176220 discloses a method in which an ERW steel pipe having a specific composition is cold-worked into a thin-walled pipe and heat-treated under specific conditions to obtain a steel pipe for HF processing. According to this method, it is inferred that the thickness deviation before the preform processing is small and the ductility is sufficient, but the occurrence of the thickness deviation and the decrease in ductility due to the preform processing are not considered. Although ductility is considered to be restored if heat treatment is performed after preform processing, there is a problem of an increase in cost accompanying the addition of the heat treatment step.

As described above, in the conventional HF processing method, H
Since the material before F processing is work hardened by preform processing, ductility is reduced, and uneven thickness occurs, it is not possible to set a sufficient amount of HF deformation, so that the shape is more than a certain level of complexity. There was a problem that parts could not be handled. The present invention solves the above-mentioned problems, and reduces the occurrence of uneven wall thickness and reduced ductility by preventing large working strain from being applied to a material before HF processing, thereby enabling a part having a complicated shape to be easily formed. It is intended to provide a processing method.

[0010]

Means for Solving the Problems The present inventors have studied diligently to achieve the above object, and as a result, by using a material having a shape that can be charged into a mold without performing preform processing, the HF There is almost no uneven wall thickness and lower ductility before processing,
The present invention has been made based on the idea that a component having a complicated shape can be handled.

That is, according to the present invention, one metal plate is folded, a predetermined portion of the metal plate is suture-welded, and the predetermined portion is cut out to form a material. This is a hydroforming method characterized by hydraulic bulging. Further, the present invention provides a method of cutting a predetermined portion from one metal plate, folding the cut portion, sewing the edge of the predetermined portion to form a material, and hydraulically bulging the material including the seam welded portion. This is a characteristic hydroforming method.

Further, the present invention provides a method of manufacturing a machine comprising a method comprising: laminating a plurality of metal plates; sewing the edges of predetermined portions of the metal plates; and cutting out the predetermined portions to form a material; This is a hydroforming method characterized by hydraulic bulging. Further, the present invention provides a method of cutting out a predetermined portion from a plurality of metal plates, superimposing them, sewing the edges of these predetermined portions to form a material, and hydraulically bulging the material including the suture weld. This is a characteristic hydroforming method.

In the present invention in the form of using a plurality of metal plates, the hydraulic bulging is carried out by using one or more metal plates separated by metal plates.
Alternatively, it can be carried out by introducing a liquid to two or more locations, and at least one of the plurality of metal plates may have a different characteristic (composition, material, plate thickness, etc.) from the others. .
In the present invention, in performing the hydraulic bulging,
If necessary, the material may be preliminarily applied with a liquid pressure to expand the material appropriately, and then inserted into a mold to perform mold bulging.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, a predetermined portion provided on a single metal plate which is folded or a plurality of metal plates are overlapped is stitch-welded, and then the predetermined portion is cut out. The material is cut out from one metal plate and folded or cut out from a plurality of metal plates and cut and superimposed on the edge of a predetermined portion to form a material, and the material is hydraulically bulged. Therefore, it is possible to freely design the shape of the predetermined portion in conformity with the shape of the part to be molded (the shape of the mold), and it is not necessary to perform a preform processing for putting in a mold. For this reason, the material metal plate before the HF processing is hardly subjected to a processing strain, and there is almost no uneven thickness or deterioration in ductility.

Therefore, according to the present invention, it is possible to easily form a component having a high degree of complexity, which cannot be formed by the conventional HF processing method using a metal tube as a raw material. As the metal plate, various steel plates such as a hot-rolled steel plate and a cold-rolled steel plate are of course usable, and a copper plate, an aluminum plate and the like can be used as appropriate. For the suture welding, laser welding, plasma welding, or the like can be preferably used. For cutting out a predetermined portion, laser cutting, press cutting, or the like can be preferably used.

In the present invention in the form of using a plurality of metal plates, the hydraulic bulging is performed by using a metal plate which is separated by a metal plate in the material.
Alternatively, it can be performed by introducing a liquid into two or more locations.
The number of locations where the liquid is introduced may be determined depending on the case. In an embodiment in which three or more metal plates are used, the inner metal plate plays the role of a beam after HF processing, and the component is strengthened. Further, the characteristics of the HF component can be further diversified by making at least one of the plurality of metal plates different from the others.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings. FIG. 1 is a schematic view showing a first embodiment of the present invention applied to molding of a T-joint part. First, two metal plates 1
(FIG. 1A). Next, the edge of the predetermined portion 4 is subjected to stitch welding (3: stitch welded portion) (FIG. 1B). Thereafter, a predetermined portion 4 is cut out to obtain a material 4 (FIG. 1).
(C)). This material 4 is provided with a seal portion 8 as an internal / external communication portion at one place. Then, the material 4 is hydraulically bulged and formed into a T-shaped joint part. In the hydraulic bulging process, the material 4 is put into a mold (constrained by the upper mold 5 and the lower mold 6), a seal head 10 having a conduction hole 9 is attached to the seal portion 8, and the material 4 is inserted into the material 4 through the conduction hole 9. Liquid (high pressure liquid)
11 is injected (FIG. 1D). The metal plate 1 was a hot rolled steel plate, the seam welding was laser welding, and the liquid was water.

FIG. 2 is a schematic diagram showing a second embodiment of the present invention applied to molding of a T-shaped joint part. First, a predetermined portion 4 is cut out from one metal plate 1 (FIG. 2A). Then, the sheet is folded at the folding margin 2 (FIG. 2B).
Then, the edge portion is suture-welded (3: suture-welded portion) to perform material 4
(FIG. 2C). The material 4 is provided with two seal portions 8 as internal and external communication portions. Then, the material 4 is hydraulically bulged and formed into a T-shaped joint part. In the hydraulic bulging process, the raw material 4 is put into a mold (constrained by an upper mold 5 and a lower mold 6), a seal head 10 having a conduction hole 9 in one seal portion 8, and another seal portion 8 Has a conduction hole 9
A liquid (high-pressure liquid) 11 is injected into the raw material 4 through the conduction hole 9 (FIG. 2D).
The metal plate 1 is a cold-rolled steel plate, the suture welding is plasma welding,
The liquid was water.

In the case of such a T-shaped joint part, in the conventional HF processing method using a metal pipe as a material, a molding failure occurs due to ductility deterioration and uneven thickness due to preform processing, so that the height of the protruding portion 7 is reduced. The number had to be limited. On the other hand, in the present invention, since the preform processing is not required as is clear from the first and second embodiments, such a limitation is eliminated, and the degree of freedom in design and manufacture is increased.

FIG. 3 is a schematic view showing a third embodiment of the present invention applied to the formation of a bent part. First, a plurality of metal plates 1 are superimposed, and the edges of the predetermined portions 4 of the metal plates 1 are stitch-welded (3: stitch-welded portions) (FIG. 3).
(A)). Thereafter, the predetermined portion 4 is cut out to obtain the material 4 (FIG. 3B). Here, the order of the suture welding and the cutting may be switched. The material 4 is provided with two seal portions 8 as internal and external communication portions. And material 4
Is hydraulically bulged to form a bent part. In the hydraulic bulging process, the raw material 4 is put into a mold (constrained by an upper mold 5 and a lower mold 6), a seal head 10 having a conduction hole 9 in one seal portion 8, and another seal portion 8 Has a conduction hole 9
A liquid (high-pressure liquid) 11 is injected into the raw material 4 through the through hole 9 (FIG. 3C).
In addition, the metal plate 1 is a hot-rolled steel plate, the suture welding is laser welding,
The liquid was water.

In the case of such a bent part, in the conventional HF processing method using a metal pipe as a material, a molding failure occurs due to ductility deterioration and uneven thickness due to preform processing, so that the radius of the bent portion is reduced. I couldn't do that. On the other hand, in the present invention, as is apparent from the third embodiment, since no preform processing is required, the present invention can be freely designed and manufactured.

The attachment of the seal head can be performed, for example, as follows. FIG. 6 is a schematic view showing one example of a method of attaching a seal head. First, a mouth-expanding jig 10A whose perimeter is larger than the length of the opening 8A of the seal portion 8 is inserted into the opening 8A to perform mouth-expanding processing (FIGS. 2A and 2B). The mouth expanding jig 10A is preferably made of a hard material such as tool steel or cemented carbide. Next, the outside of the seal portion 8 having been subjected to the flaring process is restrained by an outer surface restraining jig 12, and the outer circumferential restraining jig 12 is used to restrain the outside.
10A and sandwich the seal portion 8 to seal (FIG. 2)
(C)). When a sealing material 13 made of rubber, lead, or the like is applied to the outer periphery of the mouth expanding jig 10A, the sealing performance can be further improved.

The mouth expanding jig 10A is used as it is for the seal head 10A.
Can be used as FIG. 6 shows a mouth expanding jig provided with a conduction hole 9 used for the seal portion on the liquid injection side, but a mouth expansion jig having no conduction hole for the seal portion on the side where no liquid is injected. You just have to use a tool. In addition, it is preferable to apply a liquid pressure in advance and appropriately expand the material before putting the material into the mold, because the amount of mold bulge processing can be reduced and the final finished shape becomes sharper.

FIG. 4 is a schematic sectional view showing an HF component according to a fourth embodiment of the present invention using three metal plates. The material was bulged by applying hydraulic pressure (left> right) to the left and right chambers separated by the metal plates 1 and 1A to obtain a component having a sectional shape as shown in the figure. The inner metal plate 1A functions as a beam, increasing the strength of the component. FIG. 5 is a schematic cross-sectional view showing an HF component according to a fifth embodiment of the present invention using different thickness materials (a) and different material materials (b) for two metal plates. This allows
Characteristic ranks such as strength of parts can be further subdivided,
It becomes easier to reduce weight.

[0025]

According to the present invention, HF processing can be performed without adding a large processing strain to the material before HF, so that the applicable range of HF processing can be expanded to a more complicated shape region. It has an excellent effect.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic view showing a second embodiment of the present invention.

FIG. 3 is a schematic view showing a third embodiment of the present invention.

FIG. 4 is a schematic sectional view showing an HF component according to a fourth embodiment of the present invention.

FIG. 5 is a schematic sectional view showing an HF component according to a fifth embodiment of the present invention.

FIG. 6 is a schematic view showing one example of a method of attaching a seal head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal plate 2 Folding allowance 3 Suture welding part 4 Material (predetermined part) 5 Upper die 6 Lower die 7 Projection part 8 Seal part 8A Opening part 9 Conducting hole 10 Seal head 10A Opening jig 11 Liquid (high-pressure liquid) 12 External restraint jig 13 Seal material

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Ito 1-1, Kawasaki-cho, Handa-shi, Aichi Prefecture Kawasaki Steel Corporation Chita Works

Claims (7)

[Claims] 1. A metal plate is folded, and an edge of a predetermined portion of the metal plate is suture-welded. Then, the predetermined portion is cut out to form a material, and the material including the suture weld is hydraulically bulged. A hydroforming method. 2. A predetermined portion is cut out from one metal plate,
A hydroforming method, comprising folding the edge of the predetermined portion into a material by stitch welding, and hydraulically bulging the material including the suture weld. 3. A plurality of metal plates are superimposed, and the edges of predetermined portions of these metal plates are suture-welded. Then, the predetermined portions are cut out to form a material, and the material including the suture weld is hydraulically bulged. A hydroforming method. 4. A method according to claim 1, wherein predetermined portions are cut out from a plurality of metal plates, overlapped, and the edges of these predetermined portions are sewn to form a material, and the material including the suturing weld is hydraulically bulged. And a hydroform processing method. 5. The method according to claim 3, wherein the hydraulic bulging is performed by introducing a liquid into one or more locations separated by a metal plate in the raw material. 6. The method according to claim 3, wherein at least one of the plurality of metal plates has a characteristic different from the others. 7. The bulging process according to claim 1, wherein the material is bulged by applying a hydraulic pressure to the material in advance and then inserting the material into a mold and applying a hydraulic pressure. 7. The method according to any one of 6.