A Study on the Application of Ultrasonic Vibration to Direct Spot Welding of Aluminum Alloys (Part I)

Abstract

It was previously reported that a new spot welding machine, namely "Direct Spot Welder, "had been fabricated, which could produce good welds without any surface treatment prior to spot welding of aluminum alloys. The principle of this spot welding is breaking of the oxide film on the surface of sheets, that is, an electrical bridge as effective as the surface treatment is formed on the faying of sheets. And since the thickness of sheets was below 1.6 mm, shaking the electrode by compressed air was greatly useful.
For the sheets over 1.6 mm, however, this method was practically of no use. Then, ultrasonic vibration was applied to break the oxide film.
This report deals with the equipment for breaking the oxide film, the influence of factors of ultrasonic vibration, such as amplitude, vibrating time or pressure, etc upon the breaking of oxide film, the process of spot welding and the quality of spot welds.
As the result of the investigation, it is made clear that this method is applicable to Direct Spot Welder for thick sheets.