0.4t/h立式锅炉下脚圈和锅炉连接焊缝,以及1t/h锅炉联箱的封头和管予的连接焊缝,都是带金属垫板的单面焊结构(图1)。垫板和被焊工件1之间由于制造误差,往往存在一定间隙,焊后经常发现垫板处存在“内咬边”缺陷,即在焊缝根部的外侧垫板上有一沟槽。产生“内咬边”的焊缝必须进行返修,这样,既浪费原材料、工时,又延误工期。 The 0.4 t / h vertical boiler heel and boiler connection welds, as well as the 1 t / h boiler header headers and pipe connections, are single-side welded with metal shims (Figure 1). Because of the manufacturing error between the backing plate and the workpiece 1 to be welded, there is often a gap between them. After welding, it is often found that the backing plate has the problem of “undercut”, ie, a groove is formed on the outer backing plate of the weld root. Welds that produce “undercuts” must be repaired, thus wasting both raw materials, working hours and delays.