Spot welding method and welded joint for aluminum or aluminum alloy materials

Abstract

To provide a spot welding method for aluminum or aluminum alloy materials capable of performing welding with a low current and easily achieving a lap welding of aluminum alloy plates using inexpensive equipment without needing securement of a prescribed edge distance.SOLUTION: A spot welding method for aluminum or aluminum alloy materials comprises: a process of overlapping the first and second plates 21 and 23 comprising aluminum alloy; a steel plate arrangement process of arranging a steel plate 22 and a first plate 21 by butting the edge face of the former on that of the latter to form a butting part 24 between the plates 22 and 21; an electrode arrangement process of arranging the steel plate 22, and the first and second plates 21 and 23 in an overlapping state between a pair of electrodes; an electrification process of electrifying between the pair of electrodes to form a nugget 25 between the first and second plates 21 and 23; and a steel plate removal process of removing the steel plate 22. In the electrode arrangement process, the positions of the pair of electrodes are controlled so that at least a part of the butting part 24 is controlled in the area electrified by the pair of electrodes.SELECTED DRAWING: Figure 2

Claims

1. A superposition step in which a first sheet material made of aluminum or an aluminum alloy and a second sheet material made of aluminum or an aluminum alloy are placed on top of each other, A steel plate arrangement step involves arranging the end face of the steel plate so that it abuts against the end face of the first plate material, thereby forming a butt joint between the steel plate and the first plate material. An electrode placement step involves placing the steel plate, the first plate material, and the second plate material in an overlapping state between a pair of electrodes arranged opposite each other. A current-passing step involves passing current between the pair of electrodes to form a nugget between the first plate material and the second plate material, The process includes a steel plate removal step for removing the aforementioned steel plate, A method for spot welding aluminum or an aluminum alloy material, characterized in that, in the electrode placement step, the positions of the pair of electrodes are adjusted so that at least a portion of the butt joint is included in the region through which current is passed by the pair of electrodes.

2. The method for spot welding aluminum or aluminum alloy material according to claim 1, characterized in that, in the electrode placement step, the positions of the pair of electrodes are adjusted such that the line connecting the centers of the opposing surfaces of the pair of electrodes is positioned on the steel plate side of the butt joint.

3. The spot welding method for aluminum or aluminum alloy material according to claim 1, characterized in that the electrode placement step and the energizing step are repeatedly performed at multiple locations to form multiple nuggets.

4. The method for spot welding aluminum or aluminum alloy material according to claim 1, characterized in that the current application step includes a step of adjusting the current application conditions so that molten aluminum or aluminum alloy does not protrude from the butt joint.

5. The method for spot welding aluminum or aluminum alloy material according to claim 4, characterized in that, in the step of adjusting the energizing conditions, at least one selected from the relative position between the pair of electrodes and the butt joint, current, and energizing time is adjusted.

6. Prior to the steel plate arrangement step, there is a notch forming step in which a notch is formed on the end face of the steel plate, In the steel plate arrangement step, the steel plate and the first plate material are arranged such that a gap is formed between the notched portion of the steel plate and the end face of the first plate material. The spot welding method for aluminum or aluminum alloy material according to claim 1, characterized in that the butt joint portion includes the gap portion, and in the electrode placement step, the positions of the pair of electrodes are adjusted such that at least a portion of the gap portion is located between the pair of electrodes.

7. In the energizing process, the first plate material and the steel plate and the second plate material are pressed in the thickness direction by the pair of electrodes. When the pressure applied by the pair of electrodes in the energizing process is defined as the applied pressure P1, The method for spot welding aluminum or aluminum alloy material according to claim 6, characterized in that between the energizing step and the steel plate removal step, there is a forging step in which the pair of electrodes press the first plate material and the steel plate and the second plate material with an adhesive pressure P2 that is higher than the adhesive pressure P1.

8. In the energizing process, the first plate material and the steel plate and the second plate material are pressed in the thickness direction by the pair of electrodes. When the conditions in the energizing process are set such that the diameter of the indentation formed on the first plate material and the steel plate by being pressed by the pair of electrodes is R (mm), The spot welding method for aluminum or aluminum alloy material according to claim 6, characterized in that the width of the notch in the direction perpendicular to the thickness direction of the steel plate at the end face of the steel plate is R (mm) or more.

9. A welded joint joined by a spot welding method for aluminum or aluminum alloy material according to any one of claims 1 to 8, Between the overlapping first plate material and the second plate material, there is a nugget that joins the first plate material and the second plate material, A welded joint characterized in that the nugget is exposed on the end face of the first plate material.

10. The welded joint according to claim 9, characterized in that the nugget is not exposed on the surface of the first plate material opposite to the surface facing the second plate material.

11. A welded joint joined by a spot welding method for aluminum or aluminum alloy material according to any one of claims 6 to 8, Between the overlapping first plate material and the second plate material, there is a nugget that joins the first plate material and the second plate material, The end face of the first plate material has a projection that protrudes from the end face, The nugget is exposed on the end face of the first plate material. A welded joint characterized in that the projection includes at least a portion of the nugget.

12. The welded joint according to claim 11, characterized in that the nugget is not exposed on the surface of the first plate material opposite to the surface facing the second plate material.

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