GB1236126A - Improvements in or relating to welding - Google Patents

Abstract

1,236,126. Making valves; welding by pressure. TRW Inc. 10 July, 1969, No. 34782/69. Headings B3A and B3R. In butt welding two elements, one element is rotated relatively to the other while the elements are coaxially aligned, the elements are brought into rubbing contact and a welding current is passed through them, the relative rotation being terminated when welding temperature is reached. A headed valve stem 10 is held against rotation in an insulated movable clamp 13 and an oppositely arranged headed valve stem 18 is held against rotation in another insulated movable clamp 22. A valve tip 24 to be welded to stem 10 and valve tip 26 to be welded to stem 18 are held between the clamps 13, 22 in a conductive clamp 27 carried in a shaft 28 rotatable in bearings 31, 32 by means of gear teeth 33. An insulating spacer 29 is arranged between the tips 24, 26. In operation the tips 24, 26 are rotated and pressure is applied by rods 43, 44 to move the stems 12, 21 into contact with the tips, current is then supplied by a transformer 39 to the clamps 13, 22 to pass in series through the stems and tips causing resistance heating at the joints and when welding temperature is reached the spindle 28 is braked and current flow stopped. After welding the unit may be moved to another position and driven to allow machining of flash possibly after flash annealing. In a modification the single spindle 28 is replaced by two spaced spindles which carry a common single tip piece which is welded to the two valve stems using increased pressure for upsetting. The assembly is then moved to another station where a cutting wheel fits between the spindles to cut the single tip into two. Stems may be welded to heads and the stems may be hollow or of different metal from the valve head.