JPH11347643A - Hydraulic bulging method of plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of wrinkles by irradiating the laser beam on a thin side of lapped metallic plates in a specified thickness range and forming a welding beam having a penetration in a specified range and an interval in a specified range to control the flow-in of a material without leaving a formed bead shape. SOLUTION: A welding bead 10 is executed in a direction parallel to a material flow-in direction in a range 9 where the flow-in of a metallic plate 8 of 0.2-2.0 mm in thickness whose outer circumferential part is welded is to be controlled. A thinner plate 8a side of two lapped plates 8a, 8b is irradiated with the laser beam, and the depth (d) of the welding bead 10 is set in a range to satisfy the inequalities of 2t1<=d<=t1+t2, where t1 is the thickness of the thin plate 8a, and t2 is the thickness of the thick plate 8b. The interval W of the welding bead 10 is in a range to satisfy the inequalities 3t1<=W <=6t1. The length of the welding bead 10 is arbitrarily set by an executioner according to the quantity to control the flow-in of the material, i.e., a residual material of a plate holding part to be left behind.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic bulge forming method for a sheet material which is formed by laminating a metal material for an automobile structure, laser-welding, and then expanding by hydraulic pressure.

[0002]

2. Description of the Related Art In a conventional hydraulic bulge forming method for a plate material (FIG. 5), the outer peripheral portions of superposed plates 01a and 01b are laser-welded with a laser beam 02, and then the material is formed by upper and lower female dies 03a and 03b. , The liquid 04 is injected from a hole previously formed in one of the plates, expanded and molded.

[0003]

However, in the conventional hydraulic bulge forming method for a plate material as described above, when the cross-sectional area of the formed part 05 greatly changes in the longitudinal direction of the part as shown in FIG. The material of the plate holding part in a large area has a large inflow, causing peeling fracture of the outer peripheral welded part, unbalanced material inflow due to change in cross-sectional area, and wrinkles due to excess material phenomenon. Becomes In order to suppress wrinkles, a method of giving tension to the material during molding is generally adopted. In press molding, a molding bead 07 as shown in FIG. 7 is applied to a molding die, and tension is applied to the material during molding. Although the material inflow control is performed, in the hydraulic bulge forming method of the plate material 01, since the end of the plate material 01 is welded, the trimming step (a step of dropping excess material after forming) cannot be performed. If used, the formed bead 07 remains in the final shape of the part. Also, in the method of controlling the inflow by increasing the inflow resistance by enlarging the material shape of the portion where a large amount of material flows in in anticipation of the inflow, the material of the plate holding portion remains because the trimming step is not performed. This leads to an increase in weight due to an increase in unnecessary portions, or an increase in unbalance in material inflow into the plate pressing portion, resulting in an increase in wrinkles in the plate pressing portion. The present invention has been made in view of the above problems, and solves the above problems by controlling the material inflow of the plate pressing portion during the hydraulic bulge forming of the plate using a welding bead by a laser beam. It is intended to be.

[0004]

In order to achieve the above-mentioned object, the present invention uses a metal plate having a thickness of 0.6 to 2.0 mm generally used for automobile structural parts, and uses the metal plate. After overlapping and continuously welding at the outer periphery, the sheet material is sandwiched between the upper and lower molds, and the plate material is formed into a predetermined shape by applying an internal pressure mediated by liquid through one of the holes opened in advance. In the hydraulic bulge forming method of a plate material to be performed, a laser beam is irradiated from a thin side of the two overlapped plates to a plate holding portion in a range where the inflow of the material is to be restricted, and the laser beam is irradiated in a direction parallel to the material inflow direction. And has a penetration depth of at least twice the thickness t1 of the thinner side and up to the total thickness of the two sheets, and the interval W is 3t1 to 6t.
It is characterized by forming a weld bead having a range of 1 or less.

[0005]

According to the hydraulic bulge forming method for plate materials of the present invention,
A laser beam is irradiated from the thin side of the two overlapped plates to the plate holding portion in the range where material inflow is desired to be limited during molding, and is at least twice the thickness t1 of the thinner side in a direction parallel to the material inflow direction and on the thinner side. And the interval W is 3
By forming a weld bead having a range of t1 or more and 6t1 or less, material inflow control for suppressing generation of wrinkles can be performed without leaving a formed bead shape in a part shape.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 6 is an example of a component shape to which the hydraulic bulge forming method for a plate material according to the embodiment of the present invention is applied, in which the cross-sectional area of the component greatly changes in the longitudinal direction. When the hydraulic bulge forming of the plate material is applied to the molded part 05 having such a shape, the material of the plate holding portion having a large cross-sectional area largely flows, so that peeling fracture of the outer peripheral weld portion occurs,
There is a problem in that the material inflow is unbalanced due to the difference in the cross-sectional area in the range 06 in which the cross-sectional area changes, and the generation of wrinkles due to the surplus material phenomenon.

FIG. 1 is an explanatory view showing a welding bead for controlling material inflow according to the present embodiment. In a material 8 whose outer peripheral portion is welded, a region 9 in which material inflow is to be controlled is parallel to the material inflow direction. By applying the weld bead 10 in the direction, the material inflow is controlled without causing the above problem.

The following are the results of the verification experiments. A metal material used for automobile bodies, which has a thickness of 2.0
mm (t2) plate material 8b and 1.6 mm (t1) plate material 8
a (both are 440 MPa grade steel sheets), and after cutting into a predetermined shape, the outer peripheral portion was joined by laser welding.
Thereafter, in order to secure a required weld width with a small amount of energy in a range 9 where the material inflow is to be controlled, as shown in FIG.
Irradiates the laser beam 2 from the side, the thickness t of the thin plate material 8a
The weld bead 10 having a depth d of 1.7t1 ≦ d ≦ 2.3t1 with respect to 1 was formed. The length of the welding bead 10 was arbitrarily set by the builder depending on the amount by which the inflow of the material was to be controlled, that is, the material of the plate retainer to be left.

As shown in FIG. 3, the interval W between the welding beads 10 is 3t1 ≦ W ≦ with respect to the thickness t1 of the thin plate material 8a.
It was formed so as to fall within the range of 8t1, and hydraulic bulge molding was performed.

FIG. 4 shows the molding result. In the figure, ○ indicates that the final shape can be formed without any problem.
0 indicates that the inflow is restricted, # 1 indicates that there was no liquid leakage breakage, but the weld bead 10 was peeled off and flowed in, and # 2 could be formed into almost the final shape but liquid leaked , X indicates a broken one.

From these results, if the interval W of the weld bead 10 is in the range of 3t1 ≦ W ≦ 6t1, and the depth d of the weld bead 10 is in the range of 2t1 ≦ d ≦ t1 + t2, the weld bead 1
It was found that the inflow at the time of molding could be restricted without breaking caused by zero.

The result of this time is that the plate material 8b having a large thickness is 2 m
m, the thin plate material 8a was 1.6 mm, but if it is between 0.6 mm and 2.0 mm generally used in automobiles, the larger the plate thickness, the more the fracture caused by the weld bead 10 occurs. Therefore, it can be said that there is no problem if the above range is satisfied. In addition, as a result of performing the material inflow control by the hydraulic bulge forming method for the plate material of the present embodiment, it is possible to form the wrinkled part while suppressing the occurrence of wrinkles in a state where the material inflow control is not performed. It has become possible.

[0013]

As described above, according to the present invention,
In the hydraulic bulge forming of the plate material, it is possible to control the material inflow without leaving the formed bead shape in the formed product, and it is possible to suppress the occurrence of wrinkles.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a welding bead for controlling material inflow according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a penetration depth d of a weld bead according to the embodiment.

FIG. 3 is an explanatory diagram showing an interval W between welding beads according to the embodiment.

FIG. 4 is an explanatory diagram showing a molding result of hydraulic bulge molding of the present embodiment.

FIG. 5 is an explanatory view showing a conventional hydraulic bulge forming method for a plate material.

FIG. 6 is a diagram illustrating an example of a component shape in which a component cross-sectional area greatly changes in a longitudinal direction.

FIG. 7 is a view showing a molding bead found in general press molding.

[Explanation of symbols]

 2 Laser beam 8 Material 8a Thin plate 8b Thick plate 9 Range where material inflow is to be controlled 10 Weld bead

Claims (1)

[Claims] 1. A metal plate having a thickness of 0.6 to 2.0 mm, which is generally used in automobile structural parts, is used. The metal plates are overlapped and continuously welded at the outer periphery. In a hydraulic bulge forming method for a plate, in which the plate is formed into a predetermined shape by sandwiching the lower plate with a lower die and applying a liquid-mediated internal pressure to one of the plates through a pre-drilled hole, the flow of material is to be restricted. A laser beam is radiated to the plate holding portion in the range from the thin side of the two sheets that are overlapped with each other, and the laser beam is directed in a direction parallel to the material inflow direction and at least twice the thickness t1 of the thin side. A hydraulic bulge forming method for a sheet material, wherein a weld bead having a penetration depth up to a total sheet thickness and an interval W between 3 t1 and 6 t1 is formed.