558,072. Electric welding. BUDD MANUFACTURING CO., E. G. March 11, 1942, No. 3237. Convention date, April 30, 1941. [Class 83 (iv)] An electric spot welding apparatus comprises two carriages moved on a frame in predetermined paths by driving means carried by one carriage and connected to the second carriage on which the electrode is mounted. The work is such as a number of corugated curved sheets A is secured by clamps 42, 44 on a bed 20 consisting of a number of arched members 22 bolted together and having a number of intermediate work supporting plates 32 and a number of electrode elements 28 for co-operating with the movable electrodes 134. The clamp 44 is carried by a member 1 movable by fluid pressure through a lever 2 so that after the end of the work is secured by the clamping screws the work is drawn down by the fluid pressure device into contact with the electrode elements 28. The elements 28 may be connected together in pairs so that the current may pass in series from one electrode 134 through the work to a second electrode 134. If desired a single electrode 134 may be used the circuit being completed to the supply through the elements 28. The carriage C1 on which the electrodes 134 are mounted carries a shaft 78 provided with rollers 82 traversed in curved channel guides 66 carried by a frame F and with pinions 80 engaging racks 68 thereon. The other end of the carriage has stub shafts 79 with guide rolls 83. The shaft 78 also carries a worm wheel 86 which is driven by a worm 88 on a square shaft 90 which telescopes in a hollow shaft 184 mounted on the carriage C2. The frame F may be traversed longitudinally on rails 54 between welding operations by hand wheels 64 through worm gear 62 and rack and pinion gear 56, 58. The electrodes 134 are carried by the cylinders 132 reciprocated on fixed pistons 130 connected to members 122 pivoted at 124 on slides 96 which are movable towards and from the work in guides 94 on brackets 76 forming part of the carriage C1. The cylinders are normally maintained perpendicular to the work by a spring- pressed pivoted rod 212. The slides 96 are pushed forward so that the electrodes are in the vicinity of the work by fluid pressure pistons 112 through bell-crank levers 98 and links 102, the forward position of the slides being determined by stops 120 engaging the links 102 when the pivots 100, 104, 106 are in line. The cylinders 132 are reciprocated to effect the welds by fluid pressure supplied to opposite sides of the piston by pipes 142, 152. The carriage C1 is driven continuously at uniform speed by the shaft 184 which is mounted in a housing 182 pivoted at 178, 180 to the upper carriage C2. This carriage is mounted on wheels 156 traversed on straight guides 72 and is provided with a motor 158 which drives through speed reducing gear the shaft 184 and also through bevel gear 163, 164 and worm gear 168, 170 pinions 174 which engage fixed racks 74. The shaft 184 is connected to the speed reducing gear through a bevel pinion on a power take-off shaft engaging a bevel wheel 186 on the shaft 184. A welding transformer 190 on the carriage C2 is connected to the electrodes through flexible conductors 192 which are connected to the ends of the busbars 194 of extensible conductors, the bars being connected at one end by links 196 to the carriage C2 and at the other end are pivoted at 200 to bus bars 202 connected at their other ends to the pivots 206 on the carriage Cl. The bars 194 and 202 are pressed against each other by springs. Flexible conductors 218 connect the carriage C1 electrically to the electrodes 134. The control of the cylinders 132 and of the welding current is effected by timers engaging cams 226 on shafts driven by the motor. With the pistons 112 operated so that the electrodes 134 are brought into the vicinity of the work, the motor 158 is started and the carriages C2, C1 are traversed along their tracks at uniform speed. At each interval corresponding to the desired spacing of the welds air is admitted through pipes 142 to reciprocate electrodes 134. Due to pressure of the electrodes 134 on the work the cylinders 132 pivot about the pins 124 so that the electrodes lag behind the carriage C1 and compress the springs 218. When the electrodes are returned by pressure through pipes 152 the springs 218 return the electrode cylinders to normal position. When the carriages reach the end of their tracks the pistons 112 are reversed and the hand wheels 64 operated to move the welding apparatus to the next pair of seams, whereupon the apparatus is set for welding these seams in the reverse movement of the carriages. The carriage C1 carrying the welding electrodes can also be used for welding flat sheets.