Patent GB-862599-A (GB)
Title: Improvements in or relating to flash-butt welding machines having power-operated clamping mechanism
Inventor: YOUNG WILLIAM FORBES
IPC: B23K11/087
Filed: 1958-05-12
Abstract: 862,599. Welding by pressure; workholders. RESISTANCE WELDERS Ltd. May 27, 1959 [May 12, 1958], No. 15173/58. Classes 83 (3) and 83 (4). In a flash butt-welding machine having power-operated mechanisms for clamping the parts to be welded, to the fixed and movable heads of the machine, each power-operated clamping-mechanism comprises a fixed jaw and a movable jaw, yieldable constraining means to normally hold the movable jaw in constant orientation relatively to the fixed jaw during its movement towards and away from the latter, and means responsive to tilting of the movable jaw to stop the closing of the clamping mechanism, the constraining means being arranged to yield under the tilting tendency of the movable jaw due to a non-central obstruction between the jaws. The movable head of a flash buttwelding machine mounted adjacent a substantially identical fixed clamping head comprises a pair of upright side plates 3, Fig. 1, between which extends an upper fixed beam, formed by three members 4-6, and a lower fixed beam 7 carrying a fixed jaw 8. A movable jaw 10 is carried by a beam 11, in which are cylinders for eight hydraulic plungers flexibly connected by L-shaped supports 18 to the beam 4. Pressure fluid is supplied to, and exhausted from, each cylinder by a pipe entering a port 25 in the plunger, which communicates with an axial passage in the plunger. Cylinders 29 for lifting the beam 11 are secured to the side plates 3, and their pistons are coupled by cross-heads 35 and connecting rods 36 to the ends of the beam 11 which overlap the plates 3. An extension 40 is provided on each overlapping part of the beam 11, and a groove 43, Fig. 4, is provided at each end of the beam 11 to receive a guide bar 46 secured to a recessed portion of the corresponding side plate 3. Pressure plates 49 are secured to the beam 11 by studs 50, and are held against the guide bars 46 by springs 51 on the studs. These spring-urged plates 49 restrain the beam 11 from transverse tilting. The beam 11 is restrained from longitudinal tilting by a pair of spaced links 55 pivoted to brackets 57 on the beam and pivoted to bell cranks 60 on the fixed beam 5, the bell cranks being connected by an adjustable link 62 including a turnbuckle having portions 63, 64, Fig. 6, with spigot-and-socket connections secured by a shear-pin 66. An upstanding rod 67 on the beam 11 protrudes through a platform 71, on which are mounted two pairs of opposed switches 73, 74, Fig. 7, connected to a relay circuit controlling the supply valve for stopping the supply of fluid to the hydraulic cylinders 16. If an obstruction 76, Fig. 1, is left between the jaws at one side, and the clamping pressure exerted, the movable jaw will tilt longitudinally and apply a load to the shear-pin 66, which will yield and allow differential movement of the bell cranks. Thus the rod 67 will move to operate one of the switches 73 which causes the clamping pressure to be released. If the obstruction is so placed that the movable jaw tilts transversely, the spring-loaded plates 49 will yield, and the rod 67 will actuate one of the other pair of switches. The power unit may be an electric motor, and the relay may be fluid or mechanical.