简要介绍大客车顶盖总成的结构特点及工艺要求, 通过焊接难点分析, 决定采用顶蒙皮的富氩CO2 自动连续焊和顶蒙皮与骨架间的电阻点焊新工艺, 以达到外观和密封要求。关键词: 大客车; 顶盖总成; 连续焊; 密封性; 富氩CO2 焊Abstract: Th is article contains the brief introduction about the frame characteristics and the p rocess claim s of the coach′s roof assembly1 A nalyzing the w elding difficulty, the author decides to adop t a new w elding p rocess, that is, the automatically continuousMA G w elding used in roof sk ins and the resistance spot w elding used betw een roof sk insand roof frame. The active gas contains the rich argon and the rest carbon dioxide. In the end, the desired appearance and sealing performance are reached.Key words: Coach; Roof assembly; Continuousw elding; Sealing performance; MA G w elding