SAMPLE FOR USE IN SPOT WELDABILITY EVALUATION

PURPOSE:To enable the evaluation of weldability for spot welding done under the same conditions as those in the actual spot welding by stacking steel plates one upon another through a sheet-shaped insulator having through holes formed thereon at a specified interval so as to allow a spot welding thereof at the position corresponding to the through holes. CONSTITUTION:Steel plates 2, 4 and an insulator 10 are delivered with feed rollers 5 and 6 having them stacked one upon another as separately wound on reels 1 and 3 through the sheet-shaped insulator 10. The feeding pitch L is set so equal to that of through holes 11 formed on the insulator 10 so that the positions thereof 11 align on the centerline of electrodes 7 and 8 at the start of a spot welding. The electrodes 7 and 8 are first actuated to start the pressurization of the steel plates 2 and 4. The pressurization deforms the steel plates 2 and 4 to contact one another through the through holes 11 thereof 10 to energize. Upon the end of pressurization for the preset hour, a welding current flows to form a nugget. Thus, the spot welding can be done under the set conditions for steel plates in the actual welding thereby enabling evaluation of the weldability of the steel plates in condition closer to the actual spot welding work.