Patent GB-1075872-A (GB)
Title: Electric hard-held spot welder
IPC: B23K11/31
Filed: 1964-08-04
Abstract: 1,075,872. Welding by pressure. B. KIRSCH, [trading as FIRMA BERNHARD KIRSCH]. Aug. 4, 1964 [July 25, 1963; March 2, 1964], No. 30954/64. Heading B3R. A portable electric spot-welder comprises two or more electrode holders 6, 7 mounted on a housing 1, a driving motor (28, Fig. 4), for moving one of each pair of the holders during a welding operation, and a transformer (26) also mounted in the housing. The holder 7 is carried by a pair of arms (34, Fig. 6), within the plastics, or insulated metal, housing. Pins 15 engaging slots in the arms permit longitudinal welding movements of the arms or, with the electrodes as in Fig. 1, pivotal movement for lowering the electrode 9. Depending on the desired movement, a bolt 18 is passed through a longitudinal or lateral slot 16, 17 in the housing into engagement with the arms. The motor may move the electrode holder 7 mechanically or pneumatically. Adjacent the motor (28) is a tank in which oil, under pressure by a spring-pressed piston or a bellows, is fed to a pump in the tank. The pump supplies a cylinder (10) in the form of a handle in which a piston (31) operates a rack (30). This rotates at least one cam (33) engaging a follower rod (Fig. 5) for moving the arms (34) to operate the electrode (9), the cam also operating switches (Fig. 7) for switching on and off the electric welding current, the switches being adjustable by a disc 13. A fan (29) driven by the motor (28) may be operated independently of the welding operation, cooling air passing over the transformer to the electrodes. Attached to the arms is a bracket (38, Fig. 6) engaged by springs (40) the tension of which is adjustable by a wheel (11) so that the electrode pressure may be varied. The electrode holders may be attached at several different points (Fig. 3), a further handle may engage a hole 12, and a pressure gauge, signal lamp and a shut-off valve may be provided (Fig. 3). For spot-welding at two points two or more windings of the secondary side of the transformer may be connected in series or parallel, or two or more transformers may be used the secondary windings of which are connected in parallel while the primary windings may be connected when necessary. Switching elements may be provided between the tapping points on the primary windings. The transformer laminations may be of E- shape and located without mounting apertures. In another construction (Fig. 9), a cam (45) is fixed to the arms (34) and is lowered by engagement with a piston-rod (44) which also operates the adjustable welding current switches (42, 43. Fig. 11). In another form (Fig. 12), a pair of spaced cam tracks (45) on the electrode-holder arm exclude pivotal movement of the arm. In a further construction (Figs. 13 and 14), longitudinal or lateral movements of the arm are effected by a cylinder (52), pivotable between the directions of movement. Switches (67, 68), controlling the welding current are adjustable by a screw (56) and operated by a piston (65). Electrode pressure is adjusted by a screw (55). In another construction (Figs. 16, 19 and 20), the electrode holders (110, 111) are rotatable about the axis of an hydraulic cylinder (103) which pivots about arms (105). The arm (110) may be repositioned, using lugs (108, 109, Fig. 19), and a cage of balls (114) surrounding the piston (104) reduces friction in cylinder (103). An hydraulic supply line and the connections from the transformer are disposed on the pivotal axis (120), the electrical connections being taken to sleeves (116, Fig. 20), on the piston (104), of which one sleeve is insulated from the piston by a sleeve (117). Cooling ribs (not shown) may be provided on the cylinder, and an additional fan may be provided in the housing, or externally. Channels for cooling fluid may be provided in the piston or cylinder, the fluid being supplied to a jacket on the cylinder. The electrode holders may be replaced by stamping &c. tools for carrying out a preliminary stamping operation.