| Summary: | 碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 102 === In this study, friction stir lap welding (FSLW) of copper sheet is conducted at high rotating speeds with constant loads. Using a pinless tool made of high speed steel (HSS) with 6 mm diameter. Effects of welding time, rotating speed, and normal load on the depression depth and the interface temperature between the tool and the copper sheet are investigated for the friction spot welding. Results show that the appearance of the weld is smooth with the depression depth of 0.05 mm at the rotating speed of 21000 rpm, the normal load of 350 N, and the welding time of 20 seconds.
For the FSLW, effects of normal load and feeding speed on the depression depth and the temperature of specimen surface are investigated at the rotating speed of 21000 rpm with preheat time of 20 seconds after the friction spot welding trials. The appearance of the weld is smooth with the depression depth of 0.05 mm at the normal load of 400 N, and the feeding speed of 1.5 mm/s.
Moreover, effect of flux added on the interface between copper sheets on the joint strength is investigated. Results show that the shear strength for the cases adding flux is about 4.3 times as strong as that without flux at the rotating speed of 21000 rpm, the normal of 450 N, and the feeding speed of 1.5 mm/s.
After the experimental trials, the operation condition is selected, so that its depression depth is smaller and its joint strength is higher. The T joint of copper sheets is successfully welded at the rotating speed of 21000 rpm, the normal load of 350 N, and the feeding speed of 2.5 mm/s.
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