Forming twin spot weld connections on lead=ins - by using tubular top electrode on foil to be joined to rod

摘要

Twin spot welded joints, specially for joining a rod to a foil in the hard or quartz glass embedded lead-ins for high-pressure discharge lamps, are produced in one operation by applying a tubular electrode to one side of the foil. The preferred dia. of the bore of this electrode is 0.5 to 1.5 times that of the current carrying lead-in rod. A molybdenum foil (2) is spot welded to tungsten wires (1,6) by two spots (7) at each end before embedding in flattened quartz glass (4). The spot welds (7) are produced simultaneously by applying a tubular top electrode (8) and a solid bottom electrode (10). After the welds have been completed, their quality is checked by passing a test pulse and by checking the temperature-induced radiation of the foil surface by a photodetector (9) which produces a signal proportional to this radiation.