A resistance brazing method for galvanized steel sheets

Abstract

A resistance brazing method for galvanized steel sheets relates to the improvement of the resistance spot welding method for galvanized steel sheets. In the present invention, medium-temperature solder such as Zn-Al is placed on the two surfaces to be soldered. The solder can be sheet-like, foil-shaped, plated or sprayed on the surface to be soldered in advance, and the thickness of the solder is 0.05-0.5 mm. The electrode material can be an ordinary Cu-Cr-Zr electrode, and the electrode does not need special treatment. Set the resistance spot welding parameters, the welding current is 7000~14000A, the welding time is 10C~50C, the welding pressure is 0.7KN~5KN, start the resistance spot welding, and then let the weldment cool naturally. The invention can realize the connection without galvanized layer damage and copper pan under the premise that the galvanized steel sheet meets the strength, and improves the service life of the electrode.

Description

technical field [0001] The invention relates to a method for resistance spot welding of galvanized steel sheets. Background technique [0002] In recent years, the automobile industry in various countries has paid more and more attention to the anti-corrosion performance of materials. For example, the United States and Japan proposed that the body should be resistant to surface corrosion for 5 years and puncture corrosion resistance for 10 years. At this time, the use of painted cold-rolled steel plates can no longer meet the requirements for corrosion resistance. In order to improve the corrosion resistance of automobile body steel sheets, galvanized steel sheets have been widely used to replace painted cold-rolled steel sheets since the 1980s. The biggest advantages of galvanized steel sheets are excellent corrosion resistance, paintability, decoration and good formability. At the same time, the amount of galvanized steel sheets used in automobiles has been on the rise, ...

AI Technical Summary

Problems solved by technology

For the mass-produced automotive industry, frequent trimming or replacement of electrodes leads to a serious drop in productivity and an increase in production costs

Each car has about 3500~5000 solder joints. Due to the poor weldability of spot welding of galvanized steel sheets, the result is a series of problems in mass production: ① serious electrode loss; ② damage to the galvanized surface of weldments to damage and pan-copper; ③ prone to cracks, pores or softened tissue; ④ unstable joint strength

In addition, the failure of the electrode will cause the working part of the electrode to be processed frequently with cutting tools. At this time, a part of the metal of the electrode is removed, that is, the electrode is worn

Electrode failure will bring a series of welding defects: non-dense or unwelded solder joints, irregular shape of solder joints, impermissible indentations, burns or spots on the surface of the workpiece, surface melting, and electrode deposition on the working surface and many more

At present, although some progress has been made in spot welding of galvanized steel sheets, the problem of electrode failure in spot welding galvanized steel sheets has not been satisfactorily resolved.

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