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在通常机械产品的装配中,不少零件的紧固是由螺钉和被紧固零件上的螺孔拧紧实现的。在零件上钻孔攻丝是十分费时的工序,为了提高装配速度,人们希望能直接用螺钉钻孔攻丝或直接用螺钉攻丝,并把机械零件牢固的拧紧在一起。于是出现了各种自攻螺钉和自钻自攻螺钉。据国外报导,在机械产品上,自攻螺钉的使用达螺钉紧固总数的70％。在我国,自攻螺
In the general assembly of mechanical products, many parts of the fastening is fastened by the screws and fasteners on the screw hole to achieve. Drilling tapping on parts is a time-consuming process. In order to increase the speed of assembly, it is hoped that tapping can be done directly with screws or directly with screws, and the mechanical parts can be firmly tightened together. So there have been various self-tapping screws and self drilling screws. According to foreign reports, in the mechanical products, the use of self-tapping screws up to 70% of the total screw fastening. In our country, since the tapping