( 1. 清華大學(xué) 機(jī)械工程系， 北京 100084;
2. Department of Mechanical Engineering, University of Waterloo,
Waterloo, Ontario, N2L 3G1, Canada)
摘 要: 建立了鋁合金電阻點(diǎn)焊過程數(shù)值模擬的有限元分析模型，考察了焊接過程中電極與試件界面上接觸半徑的變化， 以及電極尖端表面上電極壓力、 電流密度和溫度的分布。 結(jié)果表明： 所考察的焊接條件下， 接觸半徑在焊接過程中逐漸增大，電極端面的中部溫度最高， 而電極壓力和電流密度均在接觸區(qū)邊緣集中。 實(shí)驗(yàn)研究發(fā)現(xiàn)電極表面上最初的點(diǎn)蝕部位呈環(huán)形， 其半徑與接觸區(qū)半徑基本一致， 由此推斷， 環(huán)狀電極點(diǎn)蝕主要是接觸區(qū)邊緣明顯的應(yīng)力集中所致。為減少電極點(diǎn)蝕提高電極壽命， 電極的形狀設(shè)計(jì)應(yīng)使電極與工件接觸界面上的應(yīng)力集中盡可能減小。
關(guān)鍵字: 電阻點(diǎn)焊； 鋁合金； 電極點(diǎn)蝕； 應(yīng)力集中； 溫度分布； 有限元法
（ 1. Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China;
2. Department of Mechanical Engineering,
University of Waterloo,Waterloo, Ontario, N2L 3G1, Canada）
Abstract: A finite element analysis model was constructed to simulate resistance spot welding process of aluminum alloys. The variation of contact radius, the distribution of stress, the current density and temperature at the electrode tip surface were calculated. The results show that during welding process the contact radius increases gradually, the highest temperature is always located at the center of the electrode tip surface, while the electrode stress and current density both concentrate at the edge of contact region. Experiments indicate that the initial pitting is in a ring form with a radius pretty close to the radius of the contact region. It is deduced that the ring form pitting can be attributed to the significant stress concentration at the periphery of contact region. To prevent pitting from occurrence and improve electrode life, the appropriate electrode design should mitigate the stress concentration at the electrode/workpiece interface.
Key words: resistance spot welding; aluminum alloy; electrode pitting; stress concentration; temperature distribution; finite element method
