过去,我车间制造的1PSD砂泵和2PN泥浆泵,由于铸件是白口铁,泵包上法兰盘的连接螺孔都是在泵包浇铸前先把加工好钢棒预制件放入铸型螺孔位置,浇铸后,再把料头用锯锯掉,钻孔攻丝。这样做往往由于工作上的疏忽,会把露在外部预制件用铁水包死,致使无法加工。后来,我们改变了制作工艺,改用活络预制件,事先把螺孔丝扣加工好,再做一件外径相同的偶件和它扭在一起,在造型时把活络预制件按图纸 In the past, the 1PSD sand pump and 2PN mud pump made in our workshop were made of white iron and the connecting screw holes on the flange of the pump bag were put into the mold Screw hole position, after casting, then cut the head sawing, drilling tapping. This is often due to negligence in the workplace, will reveal the external prefabricated with molten iron die, resulting in unmanageable. Later, we changed the production process, use active prefabricated parts, pre-threaded screw threading processing, and then do a piece of the same outer diameter and it twisted together in the shape of the active prefabricated according to the drawings