GB663186A - Improvements in electric welding systems - Google Patents

Abstract

663,186. Electric welding. CLARK, D. M. (Graham Manufacturing Corporation). Oct. 25, 1948, No. 27681/48. Class 83 (iv). An electric welding apparatus comprises a percussion block carrying a work-holder, and a plunger connected to an electric supply and adapted to impinge on the percussion block under the action of a working force to transmit simultaneously mechanical and electrical impulses to the work. In an embodiment a hammer comprises a tubular casing 10 inside the top of which is secured a block 21 of insulating material. A plunger casing 15 of insulating material which is slidably arranged inside the lower end of the casing 10, has, at its lower end, a percussion block 101 provided with a work-holder 112, secured by means of a ring 102 and a resilient washer 105. Slidingly arranged inside the casing 15 is a plunger 51, to which is secured a terminal block 55 joined by a flexible conductor 42 to a terminal block 25 secured in the block 21. To the sides of the plunger 51 are attached latch springs 85 which may engage a shoulder 81 in the casing 15. One end of a normally-relaxed spring 72 is secured to the block 25 and the other end is secured to the block 55. A resetting spring 71, normally untensioned, is located between the block 21 and the casing 15, encircling an extension 22 of the block 21, which extension 22 engages the latch springs 85 on relative movement of the casting 15 and the block 21, to press them inwardly and so release their hold on the casing 15. In operation, the hammer, holding one work-piece 201, is connected to one side of a rectifier circuit N supplied from a transformer L, while'the other work-piece 202 is connected to the other side of the network N. The work-piece 201 is held against the piece 202, pressure being applied to a handle 12 to cause compression of the springs 71, 72 and sliding movement between the casings 10, 15 until the extension 22 engages the latch springs 85 to press them inwardly, when the plunger 51 is released and impacts upon the block 101. Electric contact is simultaneously established through the block 25, conductor 42, block 55, block 101, and workpieces 201, 202. The two pieces 201, 202 are united after the impact. When pressure is released from the handle 12 the plunger 51 is retracted by the spring 72 until the latch springs 85 engage the shoulder 81. A pointed stud is employed since it is alleged that when the current initially flows the tip is heated, melts and an arc is started, the parts being united by the impact. The hammer may be employed with a direct current supply and the use of the apparatus for welding studs to a metal structure covered with an insulating material is described.