某些小型铸铁件(如缝纫机架、潜水泵吸头等)结构复杂、筋条较多、(见图1、图2)很容易损坏。这类铸件有较多的螺丝轴孔,装配精度要求较高,损坏时往往断为数块甚至数十块。由于铸铁件刚性大,故焊接时产生应力也较大,如焊接工艺不当,还会产生新的应力裂纹。为此,施焊时要控制局部温度,合理安排焊接顺序,以限制局部应 Some small cast iron parts (such as sewing machine frame, submersible pump suction head, etc.) are complicated in structure and have many ribs (see Figure 1 and Figure 2). Such castings have more screw shaft hole, higher assembly accuracy, often broken when the number of pieces or even dozens of pieces. Due to the rigidity of cast iron, so the welding stress is greater, such as improper welding process, but also produce new stress cracks. To this end, when welding to control the local temperature, reasonable arrangement of the welding sequence to limit the local should