JPH0655275A - Resistance welding method - Google Patents

Abstract

PURPOSE:To provide the resistance welding method which does not generate strain and weld traces by welding on the panel surface side when resistance welding is performed on a hem working part. CONSTITUTION:When one end including a projecting part 4 of a second planar member 2 on which a projection is formed is inserted into a folded part 3 of a first planar member 1 where the folded part 3 folded by about 270 deg. is formed on one end, a contact state between an end of the folded part 3 and the projecting part 4 is obtained on the first planar member 1 and the second planar member 2. When a welding current is then carried between the first planar member 1 and the second planar member 2, since the welding current is carried concentrating on the contact part between the end of the folded part 3 and the projecting par 4, this contact part is molten and welded. According to this welding method, since only contact points are molten and welded, resistance welding can be performed without generating the strain and weld traces by welding on the surface side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance welding method for integrally welding hemmed portions formed on the peripheral portion of an automobile door or the like.

[0002]

2. Description of the Related Art For example, in order to join a steel plate that serves as an outer panel and a steel plate that serves as an inner panel, such as an automobile door, at their peripheral portions, resistance welding is performed at the hem-machined peripheral portions to form an outer panel The inner panel is integrated with the inner panel. As shown in FIG. 3, one end of the inner panel 12 is inserted between the U-shaped bent portions 13 of the outer panel 11 whose one end is bent into a U-shape to form a hemmed portion. In order to perform resistance welding of the outer panel 11 and the inner panel 12 at the hem processing portion, as shown in the figure, the hem processing portion is connected to the first welding electrode 14, the first supporting member 15, and the second welding electrode 16. When the welding current is passed between the first welding electrode 14 and the second welding electrode 16 by being sandwiched between the first welding electrode 14 and the second supporting member 17, welding is performed at each sandwiching point. When the above-mentioned welding method is performed, welding distortion and welding marks are likely to occur on the outer surface side of the outer panel 11 in the welded portion, and the appearance is impaired in the case of automobile doors, etc. There was a necessary problem. A resistance welding method for solving the above problems of the welding method is disclosed in Japanese Patent Laid-Open No. 1-154.
It is disclosed in Japanese Patent No. 879. This resistance welding method is
As shown in FIGS. 4 (a) to 4 (e), one end of the first member 18 is bent in a U shape to form an inward projection (a), and the U-shaped bent portion is formed. The second member 20 is inserted into the central space of (b), the pressing force P is applied to the mold 21 (c), and the U-shaped bent portion is compressed to make the first member 18 and the second member After closely adhering to the member 19 of (d), the welding electrodes 22 from both sides of the U-shaped bent portion,
Projection welding is performed on the protrusion 19 by the discharge current of the capacitor 24 which is sandwiched by 23 and charged (e). According to this welding method, the first member 18
Resistance welding is performed without causing distortion or the like due to welding on the surface of the.

[0003]

However, in the resistance welding method shown in the above-mentioned conventional example, the number of working steps is large as shown in the order of working steps, and the process for forming the protrusion in the U-shaped forming portion is not performed. There was a problem that the difficulty level became high. The present invention was devised in view of the above problems, and an object of the present invention is to provide a resistance welding method that does not generate distortion or welding marks due to welding on the panel surface side when resistance welding is performed at a hemmed portion.

[0004]

In order to achieve the above object, a method adopted by the present invention is that the folded-back portion of the first plate-shaped member has a folded-back portion formed by folding back about 270 degrees at one end, Insert one end of the second plate-shaped member having the protrusion, including the protrusion, and bring the end of the folded-back portion of the first plate-shaped member into contact with the protrusion of the second plate-shaped member. ，
Resistance welding, wherein a welding current is caused to flow between the first plate-shaped member and the second plate-shaped member to weld the protrusion and the end of the folded portion abutting the protrusion. Is the way.

[0005]

According to the present invention, the protruding portion of the second plate-shaped member having a protrusion is formed on the folded-back portion of the first plate-shaped member having the folded-back portion folded back by about 270 degrees at one end. When one end including is inserted, the first plate-shaped member and the second plate-shaped member are in a state in which the end of the folded-back portion and the protrusion are in point contact with each other. Therefore, when a welding current is passed between the first plate-shaped member and the second plate-shaped member, the welding current concentrates on the contact portion between the end of the folded-back portion and the protruding portion, so that this contact The parts are melted and welded. According to this welding method, since only the contact point between the end of the folded portion of the first plate-shaped member and the protrusion of the second plate-shaped member is melted and welded, the distortion due to welding on the surface side Resistance welding can be performed without generating weld marks or welding marks.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. The following embodiments are examples of embodying the present invention and do not limit the technical scope of the present invention. FIG. 1 is a schematic diagram showing a structure for carrying out the resistance welding method according to the present invention, showing an embodiment in which the door outer and the door inner of an automobile door are resistance welded at a hem-processed portion formed on the peripheral portion. 2 is a sectional view taken along the line AA in FIG. In FIG. 1, one end of the door inner 2 (second plate-shaped member) is inserted into the central space of the folded-back portion 3 in which one end of the door outer 1 (first plate-shaped member) is folded back to 270 degrees, and the hemming portion is formed. Is formed. As shown in FIG. 2, protrusions 4 are formed at predetermined intervals at a portion of one end of the door inner 2 to be inserted into the folded-back portion 3, and when one end of the door inner 2 is inserted into the folded-back portion 3, the protrusion is formed. 4 and folding part 3
Point contact with the edge of. Since the protrusion 4 is formed on the flat plate-like portion at one end of the door inner 2,
Can be easily processed at the time of forming. As shown in FIG. 1, with respect to the hemmed portion formed as described above, the outer surface side of the folding back portion 3 (the side which becomes the surface of the door) is supported by the first support member 6, and the inner surface of the folding back portion 3 is supported. The first welding electrode 5 is brought into contact with the side (the side that becomes the back surface of the door), and the door inner 2
The required position is clamped by the second supporting member 8 and the second welding electrode 7. From this state, the folded portion 3 is pressed by the first welding electrode 5 and the first bearing member 6, and the second welding electrode 7 is pressed.
When the required position of the door inner 2 is pressurized by the second supporting member 8 and the welding current is passed from the welding transformer 9 between the first welding electrode 5 and the second welding electrode 7, the welding current is , The first welding electrode 5 to the end of the folded portion 3, the protrusion 4, the door inner 2 to the second welding electrode 7. Since the welding current flows intensively between the end of the folded-back portion 3 and the protrusion 4 which are in point contact, the contact point between the end of the folded-back portion 3 and the protrusion 4 is melted. After applying the welding current for a predetermined time, the energization is stopped to release the pressure applied by the first welding electrode 5 and the first supporting member 6 and the second welding electrode 7 and the second supporting member 8. Then, resistance welding is performed by melting the end portion of the folded-back portion 3 and the protruding portion 4. Folded part 3 of the above welding
The same applies to each point where the end of the door and the protrusion 4 come into contact with each other, so that the door outer 1 and the door inner 2 are welded to each other at the peripheral hemming portion. The welding current by this resistance welding method is concentrated at the contact point between the end of the folded portion 3 and the protrusion 4 as described above, and does not flow to other portions. Therefore, melting by the welding current is only at the contact point. Therefore, it is possible to perform resistance welding on the front surface side of the door outer 1 without distortion or welding marks due to welding.

[0007]

As described above, according to the present invention, the first folded portion having the folded portion which is folded back by about 270 degrees is formed at one end.
A protrusion formed on the folded-back portion of the plate-shaped member
When one end of the plate-shaped member including the protrusion is inserted, the first plate-shaped member and the second plate-shaped member are in contact with each other at the end of the folded portion and the protrusion. Therefore, the first
When a welding current is caused to flow between the plate-shaped member and the second plate-shaped member, the welding current concentrates on the contact portion between the end portion of the folded portion and the protruding portion, so that this contact portion is melted. Welding is done. According to this welding method, since only the contact point between the end of the folded portion of the first plate-shaped member and the protrusion of the second plate-shaped member is melted and welded, the distortion due to welding on the surface side It is possible to provide a resistance welding method that does not generate welding marks.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an embodiment for carrying out a resistance welding method according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a perspective view showing a configuration for carrying out a first conventional resistance welding method.

FIG. 4 is an explanatory view showing a process sequence of a second conventional resistance welding method.

[Explanation of symbols]

 1--Door outer (first plate-shaped member) 2--Door inner (second plate-shaped member) 3 --- Folded-back portion 4 --- Projection portion 5 --- First welding electrode 7--Second welding electrode

Claims (1)

[Claims] 1. An end including the protrusion of a second plate-shaped member having a protrusion is formed on the folded-back portion of a first plate-shaped member having a folded-back portion that is folded back about 270 degrees at one end. And the end of the folded-back portion of the first plate-shaped member and the protrusion of the second plate-shaped member are brought into contact with each other, and are inserted between the first plate-shaped member and the second plate-shaped member. A resistance welding method comprising applying a welding current to weld the protrusion and the end of the folded portion that abuts the protrusion.