热时间常数在QBe2箔与Cr20Ni80丝电容储能点焊中的应用

Application of thermal time constant in capacitor discharge spot welding of QBe2 foil and Cr20Ni80 Wire

为了满足微型电机电刷零部件的使用要求,根据计算所得的热时间常数τ及其与焊点中心部分温度上升的关系曲线,确定了QBe2铍青铜箔与Cr20Ni80镍铬丝微型件电容储能点焊工艺参数的选取原则。根据所选的工艺参数,采用电容储能点焊机对试样进行焊接,并对焊接接头的金相组织、微区成分进行了分析试验。结果表明,利用热时间常数选取的工艺参数,可以获得良好的固相连接接头,但焊接界面铍青铜一侧有晶界局部熔化现象,镍铬合金中的镍与铬元素向铍青铜一侧有较明显的扩散。由此可知,根据热时间常数选取焊接工艺参数的原则是合理可行的。

In order to satisfy the using demand of electrical brush spare parts of micro electric-machinery in this paper.QBe2 Beryllium Bronze foil and Cr20Ni80 Nichrome wire were joined together with capacitor discharge spot welding machine.Selecting principle of welding process parameters was defined according to the calculated thermal time constant and the relation curve of temperature rising in the central part of solder.The metallographic structure,micro-range composition and mechanical property of welding joint were analyzed and tested.Nice welding joint can be acquired in minisize workpiece production process of beryllium bronze and nicochrome wire with capacitive storage spot welding machine.There is grain boundary partial melting at the welding interface on the side of beryllium bronze.Nickel and chromium in Ni-Cr alloys diffused into beryllium bronze evidently.The principle of choosing welding process parameters by using thermal time constant mentioned in this paper is feasible.