Patent GB-893247-A (GB)
Title: Improvements in or relating to method and apparatus for welding and a welded product
IPC: B23K11/02
Filed: 1958-12-23
Abstract: 893,247. Making valve tappets; welding by pressure. THOMPSON, E. A. Dec. 23, 1958 [Dec. 30, 1957], No. 41542/58. Classes 83 (2) and 83 (4). In joining a cast iron member 446 to a steel member 414 having a higher melting temperature than the cast iron, the surfaces of the members are abutted, the members are heated at the joint to a temperature above the melting point of the cast iron but below the melting point of the steel and a welding force is applied to the members to upset the steel and cast iron laterally, the outward lateral flow of the softened steel and molten cast iron being limited. An apparatus for welding cast iron heads 446 to steel tubular bodies 414 of valve tappets comprises a main base 10, Fig. 1, having a bed plate 14 with a dovetail guideway and at the ends of the bed are secured a pair of blocks 16, 18. Slidable in the left-hand end of the guideway is the base 28, Fig. 9, of a head 26 with a bracket 30 carrying a nut 32 in which is threaded a haft 34 rotatable but axially fixed in the bracket 16. The shaft has flats to allow adjustment of the head 26 in the guideway. A copper alloy electrode 46 with a copper alloy jaw 48 is secured to the bracket 30 by a ball-and-socket connection 40, 42, 44 and by spring-loaded screws 52 and is connected to a laminated busbar 50. A rod 58 with stop nuts 60 at one end passes through a bore in the base 28 and is screwed to a socket 62 in a turret head 70. The head has dovetail slides in the guideway and carries a shaft 74 secured to a water-cooled cylindrical turret 76 having indexing holes 78 in a lower part for co-operation with a bolt 80 on a piston 82 in a cylinder 84 and the upper part 102 of the turret of copper alloy, is engaged by the jaw 48 and has five or more work parts receiving cavities in its periphery. A head 108, Fig. 1, similar to head 70 and carrying a turret 110 similar to turret 76 but without indexing means is mounted in the guideway and is coupled to a head 112 similar to head 26 except for its connection to bracket 18 which is by way of a screw shaft 122 rotated by a rack- and-pinion drive, the rack being on a piston in a double-acting cylinder 130. The head 26 remains in a stationary adjustable position with a spring 146 tending to urge the head 70 away therefrom, the head 108 tends to be urged away from the head 112 by a similar spring and the two latter heads may be moved along the guideway together by the threaded shaft 122. The cavities in the peripheries of the turrets are provided with part annular liners 148, Figs. 13, 14, with one or more contact members 152 therein and positioned in and insulated from the liner is a part annular stainless steel die member 156. A stationary recessed block 164, Fig. 3, at the mid-portion of the bed supports a nut 170 in which is threaded a hollow workpiece abutment 172, the nut 170 being rotatable by a ring and worm gear 176, 178 to adjust the position of the abutment 172. An hydraulic motor 192 in the base has a piston-rod extension 206 slidable in the hollow abutment 172. A frame member 212, Fig. 3, is mounted across the guideway and slidably supports a pair of rods 220 carrying a platen 218 clamped to the rod 228 of the piston 236 of an hydraulic cylinder 234. Above the cylinder 234 is an intensifier piston and cylinder below an air accumulator 254. The lower end of the platen is secured to a water-cooled bus-bar 264 carrying an electrode holder 274 for a hollow watercooled electrode 276 located above the point of tangency of the turrets. A transformer is connected, one side to the bus-bar 264 and the other side to the turrets by the bus-bars 50. The shafts 74 of the turrets 76, 110 are coupled through universal joints 278 to shafts carrying meshing gears 286, 288, gear 286 being driven from a pinion 298 on a shaft 300 which carries a pinion meshing with a rack on a piston in a double-acting cylinder to effect its rotation and is connected to a piston in a further cylinder for effecting vertical movement of the shaft. An automatic feed means for the steel workpieces comprises an upstanding frame 416, Fig. 30, secured to the bed, in which is slidable an upper shuttle 422 and a lower shuttle 424 connected by a lever 426 pivoted to the frame, the lower shuttle being connected to the piston of a fluid motor 385. Workpieces are received from a conveyer tube 438, moved forward by the upper shuttle to fall through a hole over a shoot 444 and are then pushed by the lower shuttle on to a platform 412 and into one of the cavities in the turret 76. The workpieee is held in the cavity by an L-shaped guide rail. An automatic feed means for the cast iron workpieces comprises an inclined gravity track 448, Fig. 26, on which the workpieces are released by a rocking escapement lever 452 controlled by a cam 460 actuated by a steel workpiece carried in the turret. The piston of a fluid motor 391 pushes the workpiece at the bottom of the track into a cavity in the turret 76. A finished work ejector 277, Fig. 1, overlies the turrets to eject the work into a shoot 281. In operation the motor 385 is operated through forward and return strokes to move a tubular steel member 414 into a cavity. The motor 391 is operated to push a cast iron member into a cavity above a previously fed member 414. The motor 130 is operated to turn the screw 122 and retract the head 112, the jaw 48 first separating from the turret 110 and then the jaw and turret retract together. The turret 76 is pushed forward by spring 146 to separate the turret 76 from the jaw 48 and then the turrets 76, 110 separate. The motor for operating the rack to rotate the shaft 300 is operated to index the turrets to advance the turrets one cavity. Motor 84 is operated to raise the locking pin 80 and the shaft 122 is rotated to advance the turret 110 and so clamp tubular steel workpiece between the cavities. The workpiece makes good contact with the members 152. The die 156 is positioned alongside and spaced from the join between the two parts (see Fig. 22), and the motor 192 is operated to raise the pin 206 to centre the cast iron workpiece 446 and the electrode 276 is lowered into contact with the cast iron piece and then the pin 206 is lowered. The intensifier is operated to apply increased pressure by electrode 276 and then the transformer is energized. The steel tube softens and the cast iron locally melts and under the pressure the soft and molten metals flow into contact with the cold die 156 (see Fig. 24) and with the portion of the workpiece 446 which extends within workpiece 414. The cast iron pieces may be preheated and the parts to be joined may have thin coatings of a different metal. Automatic operating means for the machine are described.