Study on the Process Parameters of High Frequency Induction Welding and its Property Influences in the Brazing of SMA Connector Body

• Main Authors: Cheng-Kang Wang, 王正綱
• Other Authors: 李春穎
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/7faubv

碩士 === 國立臺北科技大學 === 自動化科技研究所 === 102 === For conventional flame welding, the formation of thick oxidation layer on surface due to the extensive heating duration usually causes the deterioration in the thermal transfer of the process. Moreover, the flame can easily reaches 1100℃ to 3300℃ which is far higher than the melting point (931℃) of the brass used in the connector body. Especially for the small workpiece with dimensions of 15×15×7 mm, a local heating for the welding will be infeasible. On the other hand, with an induction heater of single coil and 2 mm in diameter, the heating zone can be easily controlled within 5 ~ 8 mm range. The alternating magnetic field supplied by the induction heater generates the eddy current on specimen surface and converts the electric energy into thermal energy. Since the induction magnetic field is confined near the coil, the effectiveness of local heating is obtained. In this study, an SMA (Sub Miniature version A) connector body was used to investigate the brazing process by employing silver alloy filler and flux. Brazing was performed under different heating time, flux formula and power rating, and the quality of the brazing joint was examined. The residues from the spray of flux were also recorded. Moreover, the variation in the microstructure and hardness in the heat affected zone was also examined. Depending on the power rating of the induction coil, the hollow cylinder with 5.3 mm diameter was able to be brazed within 4.5~6.5 s. However, it was found that with heating time of 5.6 s and 80% power rating, the brazing joint could reach the best quality. The splashing and the residual amount of flux near the brazing joint for different paste formula was also compared.