Patent GB-1231971-A (GB)
IPC: B23K20/12
Filed: 1969-01-09
Abstract: 1,231,971. Welding by pressure. CATERPILLAR TRACTOR CO. 9 Jan., 1969 [12 April, 1968], No. 1332/69. Heading B3R. [Also in Division F2] A reciprocatory friction welder for holding and reciprocating one workpiece relative to another includes a variable displacement mechanism between the power source and the reciprocable workpiece-holding member, operable to vary the relative reciprocable displacement of the holding member and a second workpiece between zero and a predetermined value. In one embodiment (Fig. 1), the variable displacement mechanism 24 includes a link 72 having a slot 78 along which a fulcrum pin 74 is positionable by a piston-and-cylinder arrangement. One end of the link 72 is pivoted to a connecting rod 47 which reciprocates in response to rotation of a drive shaft 30 on which the rod is eccentrically mounted. The link, whose other end is pivoted to a drive rod 79 connected to a holder for one workpiece, pivots about the fulcrum pin 74 and thereby reciprocates the workpiece holder with an amplitude dependent upon the position of the pin along the slot. At the drive rod end of the link the provision of an offset bracket 96 allows the fulcrum pin to be moved into a position coaxial with the pivot 83 of the drive rod 79 to the link, whereby the reciprocatory motion of the drive rod ceases although the drive of the welder is still running. With such zero displacement of the drive rod, two workpieces to be welded are held in correct alignment. Drive shaft 30, which is driven from a motor (not shown) via a belt-and-pulley 26, 28 is provided with a blade disc 44 against which brake blocks 38 may act by operation of a lever 40 and cam 42, to stop rotation of the shaft. Means 22 is provided to dynamically balance the moving parts of the link mechanism 24 and connecting rod 47. Both the connecting and drive rods 47, 79 respectively are guided by guides 89. Welding pressure is applied to the workpieces by means of an assembly 20 including a notched lever 66 engaging a ridged block 68 secured to a block 54 forming part of the reciprocable workpiece holder, loading pressure being applied to the lever 60 by a selected weight 70. In another embodiment (Fig. 4), a carriage 108, slidable on a splined shaft 118 and guided by guides 110, 112 on the frame 104, supports the variable displacement mechanism 102 which includes a member 120 journalled for rotation at each end, and being increasingly eccentric relative to the shaft 118 as the righthand end (as shown) is approached. A bearing 124 slidably connects the eccentric 120 to the guided drive rod 122 for the reciprocable workpiece holder 126. With the carrier 108 in a position adjacent the motor 106, rotation of the shaft 118 does not lead to reciprocatory displacement of the rod 122, but as the carrier is moved away from the motor by the piston-andcylinder arrangement 114, 116, the eccentric 120 slides within the bearing 124 to cause reciprocation of the rod 122 with increasing amplitude. Kinetic energy may be stored in the shaft by the provision of a flywheel 134. Upsetting pressure may be applied once the workpieces have been brought into plastic state and alignment, i.e. when they experience no relative reciprocation. Specification 1,161,800 is referred to.