Patent GB-930441-A (GB)
Title: Improvements in fluid-operated pressure-applying devices such as pressure-equalizingresistance welding device
IPC: B23K11/31
Filed: 1959-10-19
Abstract: 930,441. Welding by pressure. M. H. WOLFBAUER. Oct. 19, 1959 [Oct. 23, 1958], No. 35360/59. - Class 83 (4). In a pressure-applying device having a mounting base and an hydraulic or pneumatic drive to apply pressure on a workpart through a tip carried by one of the drive elements, an arrangement mounting the drive on the base to permit axial reciprocation of the drive relative to the base is free of the forces in those constructional elements of the device which transmit the pressure applied to the workpart. A resistance welding gun comprises a cylinder 17 whose double piston 24 carries on an extension 30 of its front end 28 one welding electrode 35, the other electrode 39 being on a carrier 41 supported on a yoke member 45 clamped by parts 45a and 47 on to the forward end of the cylinder. The piston-rod 20 connects two heads 26, 28, the head 26 being in a chamber 14 supplied with pressure fluid through a port 21 or a port 23 and the pressure on the rear sides of the heads being equalized. The yoke member 45 has bifurcated sides 45b which are pivoted at 67 on a head 63 secured to a shaft 15 slidable in a bore 13 of a base 9 on a support 11. An adjustable bar 49 in the base carries a bifurcated finger 57, the sides of which each has a slot 61 to coact with a pin 59 on the extension 30 which moves between the sides of the finger. A bar 75 bolted to the rear end of the shaft 15 provides a stop and rest for the rear end of the cylinder through a clevis 83 which is connected to one end of a spring 19 whose other end is connected to an anchor on the end of the shaft 15. An adjustable stud 73 is carried in the bar 75 extending towards the base 9 and an adjustable screwed rod 89 is also carried on the bar, the rod having a flange to engage a compression spring 95 in a blind hole 99 in the base and a portion disposed within the spring. A similar rod 91 is provided on the head 61 to engage a compression spring 97 in a bore 101 in the other side of the base 9. In operation with the parts in the positions shown in Fig. 1 and after a weld has been performed on work W, air is admitted to the chamber 14 through port 23 to move the piston and electrode 35 to the left. The cylinder moves to the right carrying the electrode 39 to the right, the shaft 15 sliding in the base 9 until the position shown in Fig. 2 is reached with the pin 59 engaging the slots 61 and the stud 73 engaging the base 9. The air acting on the head 26 now causes the cylinder to rotate about the pin 59 to tilt the electrodes 35, 39 away from the work and to stretch the spring 19. With new work W<SP>1</SP> in position, Fig. 3, the air is now supplied to the port 21, the spring 19 contracts to return the cylinder to its normal horizontal position and the piston moves to the right until the electrode 35 engages the work. The cylinder moves to the left and brings its electrode 39 into contact with the work into the position shown in Fig. 1. The gun may be operated without tilting by adjusting the stud 73 so that it does not contact the base and by inserting a fastener into a passage 71 in the part 45 and head 63. The pressure of the springs 95, 97 may be adjusted so that one of the electrodes remains stationary. The springs 95, 97 and the stud 73 may operate against the slide bar 49 or the base 9 may be longitudinally adjustable. If it is desired to use the tilting movement without pressure equalizing the electrode 39 may be removed from the member 45 and fixed to a support. Alternatively, using a separate fixed electrode 79, the cylinder may be pivoted by means of a bell-crank device.