C_(50)型貨車的魚腹形中梁(如图1)系由450毫米的工字鋼切割压制后焊接而成。每辆車共有四条这样的焊縫,全长13米。原设計用单边坡口手工焊接,工作量大,生产率低,而且焊縫质量不高,钻孔檢查时常常发現夹渣和垂直边未熔合等缺陷。在大闹技术革命的群众运动中,我們采用自动焊代替手工焊焊接魚腹焊縫,取得了良好的效果。 The belly-shaped middle beam of the C_ (50) truck is welded by 450 mm I-beam cutting and pressing. A total of four such cars per car, a total length of 13 meters. The original design with single-sided groove hand welding, heavy workload, low productivity, and the weld quality is not high, drilling inspection often found defects such as slag and vertical edge fusion. In the Mass Rapid Rebellion Movement, we used automatic welding instead of manual welding of fish-belted welds and achieved good results.