GB712498A - Devices for clamping workpieces of web and flange section - Google Patents

Abstract

712,498. Welding by pressure ; work-holders. RESISTANCE WELDERS, Ltd. Oct. 17, 1952 [Oct. 19, 1951], No. 24483/51. Classes 83 (3) and 83 (4) A device for clamping a metal section having a web and a flange, has two fixed surfaces at right angles to each other to engage two surfaces of the section and two movable clamping members each acting to urge the section against one of the fixed surfaces, the clamping members being brought into action one after the other by the introduction of fluid to a single fluid pressure motor. In an embodiment a clamping device, two of which are provided on a resistance welding machine for welding window frames, one on the movable head and one on the fixed, has fixed surfaces 12, 13 on a block 11. Co-operating with these are two heads 19 on levers 17 pivoted at 18 to a base 10 and a jaw 27 on an arm 24 pivoted at 25 in blocks 26 sliding horizontally in guide surfaces in the base. Arms 33 pivoted at 34 to the base and arms 32 pivoted at 39 in blocks 41 sliding horizontally in guides in the base are pivoted together and to a head 35 at 34a. Levers 31 are pivoted to the blocks 41 at one end and to the pivot 25 at the other. The rod 55a of a piston 55 in a cylinder 36 is screwed to the head 35 and the cylinder 36 has lugs 56 with pins 57 which engage in slots 58 in lugs on the base. In the closed position shown in the Figure the heads 19 are held on to a workpiece at right angles to the arm 24 by springs 20 acting on the lever 17 while the jaw 27 is held on the workpiece by pressure exerted by the rod 55a. To release the clamp fluid is admitted to the bottom of the cylinder to cause the cylinder to move downwardly relative to the piston to move the pins 57 towards the bottom of the slot 58. In so doing the pins engage the levers 17 and rotate them to release the work. The piston is raised and in turn the pivot 34a. The toggle is moved to cause the arms 31 to push the pivot forwardly, surfaces on the arm 24 sliding on surfaces 29 and 52 on the base. The jaw 27 releases the work and the arm 24 continues to move horizontally until pins 37 on the arm 24 engage stops 38. Further movement of the levers 31 rotates the arm 24 about the pins 37 to raise the arm 24 to an inclined position. Fluid now admitted to the top of the cylinder causes firstly the cylinder to rise until the pins 57 reach the top of slot 58 to allow the springs 20 to press the' heads 19 on the work and further fluid lowers the piston and hence pivot 34a to straighten the toggle and move the arms 31 rearwardly. The arm 24 is rotated until it reaches the horizontal and is then pulled rearwardly so that jaw 27 clamps the work. The pivot 34 is eccentric to adjust the position of the piston rod relative to the arm 24. The fluid supply to the two cylinders on a welding machine may be supplied from a common valve.