GB797020A - Welding apparatus - Google Patents

Abstract

In a flame-welding machine having a welding unit and a tracing unit rotatably supported on spaced axes normal to a work plane and linkage interconnecting the units for moving them simultaneously along parallel paths, rotation of the tracing unit about its axis effects an equal rotation of the welding unit. The machine is particularly adapted for forming weld joints of lead, but may be used for coating, e.g. steel plate with lead, or for applying fusible material such as organic thermoplastic resins. As shown, a trolley 195, Fig. 9, in which the tracing unit 196 is rotatably mounted runs on rails 211 mounted on a carriage 214 movable along fixed transverse rails 217, 218. The welding unit 31 has a frame 57 carrying wheels 65 arranged to run on the workpiece and a supporting shaft 175 rotatably mounted in a block 178 on a threaded rod 179 journalled in a gear carried by an arm 194 secured to the trolley 195. Rotation of the shaft 197 of the tracing unit 196 varies the setting of a potentiometer 205, Fig. 11, forming part of a bridge circuit. The unbalanced current is detected by a double-acting relay 193 which connects up a reversible shaded pole-type motor 187 to rotate the shaft 175 of the welding unit and the arm 185 of a potentiometer 186 until the bridge circuit is balanced and the relay 193 released. A container 56, Figs. 5 and 7, charged with pieces of lead is heated internally by an electric heater 148 or externally by a gas burner to melt the lead. The container 56 is reciprocatably mounted in the frame 57 and carries an electric motor 67 driving a camshaft 71 and a gas torch 110. The camshaft 71 is driven continuously and carries cams or eccentrics which through a pawl and ratchet mechanism 138 intermittently rotate the wheels 65, reciprocate the container 56 transversely of the frame 57, lower the torch 110 during the forward movement of the welding unit 31 and momentarily lift a valve 92 to release molten lead at an instant halfway through the advacing movement of the welding unit 31 at which time the container 56 is centred relatively to the frame. A radius arm rotatable about a fixed pivot may be secured to the shaft 197 if circular welds are to be performed. In a modification, Fig. 1, the welding and tracing units 31, 30, respectively, are secured to a pantograph supported on a fixed rod 4. The effective <PICT:0797020/III/1> <PICT:0797020/III/2> <PICT:0797020/III/3> <PICT:0797020/III/4> <PICT:0797020/III/5> lengths of the arms of the pantograph are adjusted by rotating gears 18 and 34 to turn screwed rods 22 to move the pivot points 10, 11 relative to the arms of the pantograph. The shafts 169, 46 of the tracing and welding units 30, 31, respectively are connected to the armatures of motors 15, 47 forming part of a selsyn transmission so that movements of the shaft are synchronized.