附图所示为铅螺套零件,在螺纹成形前,需先将铸造的铅饼反挤成筒,然后切边。过去挤筒前先用水把毛坯冲洗干净,凉干后再挤,废品率很高,有时达75％。废品形式为周边高低相差过大,以至最低处达不到总高要求,其次是开裂和嵌在凹模内取不出来等。 Figure shows the lead screw parts, before the thread forming, you must cast the cast anti-extrusion into the cylinder, and then trimming. In the past, the raw water should be used to rinse the raw material before squeezing, then squeezed when dry. The rejection rate is very high, sometimes up to 75%. Waste in the form of a difference between the surrounding high and low, and even the lowest total less than the total high demand, followed by cracking and embedded in the die can not take out and so on.