Joining two metal strips coated with insulating material - where heated spot welding electrodes are used to melt coatings before making spot welds in lap joint

摘要

The tail end of one strip is placed over the front end of another strip so the ends overlap. Heated spot welding electrodes are first used to melt the insulation present on at least one side of each strip, and are then employed to make spot welds, so the lap joint will withstand tensile and bending stresses. The insulating coatings may be made of a polymer. The adjacent ends of the two strips are pref. first cut obliquely, esp. at 30 deg., and then the overlapping ends are stuck together by heat before being further heated by the spot welding electrodes. Each electrode is pref. provided with an electric resistance heating coil, and the electrodes may consist of rollers producing seam welds. Process is used esp. where the strip is to be wound round a cable, where continuous strip is required, and where the joints must be strong and will conduct electricity.