田口方法對車身高張力鋼板點銲最佳化製程研究

Abstract

在汽車板件熔組的製程中，點銲作業為其主要的製程，影響點銲件品質之製程參數頗多，亦影響車身之剛性及相關機械性質甚鉅。主要參數包括銲接電流、加壓力、通電時間、電極頭的尺寸及銲件表面的狀況等。由於能源危機與環保意識的提升，使用高張力鋼板以降低車身重量，改善車輛油耗的需求日益強烈。本研究應用田口方法的實驗配置，在高張力鋼板銲接製程參數最佳化中，期能以較少的實驗次數，有效率的取得製程中之最佳參數值。另外，透過變異數分析（Analysis of Variance, ANOVA）找出各製程參數之影響程度[15]。 本實驗結果顯示：(1) 藉由田口方法所找出軟鋼板及高張力鋼板點銲製程參數的設定值，可滿足RWMA (Resistance Welders Manufacturers Association，電阻銲接機製造商協會) 的強度需求，亦得到較現行製程參數設定值所銲製之銲點更高的強度。(2) 最適值參數所銲製之銲點雖可得到較高的拉剪強度，但會造成電極的使用壽命嚴重地減少。(3) 權衡值參數所銲製之銲點其拉剪強度雖不為最佳，但可使電極使用的壽命提升，且亦獲得能滿足RWMA的強度需求的銲點。

The resistance spot welding (RSW) is a major manufacture procedure for the vehicle automobile body assembly. The quality of RSW weldment is heavily influenced by welding current, welding time, electrode force, the size of electrode tip, and surface condition of specimens, etc. Because of the energy crisis and environmental consciousness, new sheet metal is developed and used to reduce automobile body weight. The Taguchi method was used to determine optimum process parameters in high- strength steel sheet using RWS process. The degree of influence by process parameters was also investigated through Analysis of Variance (ANOVA). The experimental results show that: (1) By using the welding process parameter that the Taguchi method determined, the shear strength of the weldment can meet RWMA requirement and even better than the value by using current process parameter; (2) Higher shear strength can be obtained, but the service life of the electrode will be reduced; (3) An optimum parameter can be found to increase the service life of the electrode and the shear strength of the weldment can still meet the RWMA requirement.