Patent GB-560376-A (GB)
Title: Improvements in and relating to electric welding apparatus
IPC: B23K11/08
Filed: 1942-08-28
Abstract: 560,376. Conveyers with rack railways ; traversers. GROVES, W. W. (Briggs Manufacturing Co.). Aug. 28, 1942, No. 12133. [Classes 78 (i), 78 (iv), and 104 (ii)] [Also in Groups XXII and XXXII] An electric welding apparatus, for welding the several parts of a vehicle floor assembly, comprises a track along which a work carriage is moved step by step successively under each of a number of groups of welders supported above the track, the carriage during the intervals of rest being lifted off the track to position the work in operative relation to the adjacent group of welders and being subsequently returned to the track and means responsive to the return movement of the carriage being provided to index the carriage along the track. The apparatus may have two parallel conveyers, one for conveying the carriages under the welders and the other for feeding the carriages from a loading station, cross conveyers at each end thereof being provided respectively for transferring a loaded carriage from the loading conveyer to the welding conveyer and for transferring an empty carriage to the loading conveyer. The work is mounted on wheeled carriages 38 provided at each end with bumpers 59 and successively fed along tracks to three welding stations 46, 47, 48, by the engagement with a pivoted latch 73, Figs. 9 and 11, on the forward end of the carriage on the cross-conveyer 41 of a hook 69 on a rack 68 in gear with a pinion 67, which is driven through a second pinion on the same shaft by a rack 62 reciprocated by a double-acting fluid-pressure piston 60 controlled by a pair of solenoid-operated valves. At each station are two separate groups of welders comprising two independently controlled sets of,fluid-operated electrodes 49, 50, 53, 54 and 57, 58. The positions of the carriages under the welders are determined by a pivoted latch 93, Fig. 13, operated by a fluid pressure cylinder controlled by a solenoid operated valve.. The carriages are in contact with each other during traverse on the welding conveyer. The movement of the carriages under the welders is braked by brake strips 81, Fig. 17, on the carriages engaging brake shoes 80 on the framing. The brake shoes are pressed upwards by springs 82 and are also operated by a fluid operated cylinder 86 at the front ends thereof under control of a solenoid-operated valve to stop the carriage at the end of the indexing movement. An abutment 84 on the shoe 80 engages an abutment 85 on the framing to prevent longitudinal movement of the shoe. The carriages when moving on to the discharge conveyer 44, Fig. 23, are braked by a shoe 202 operated through levers 204 by a fluid pressure piston 206 controlled by a solenoid-operated valve. The bumper 59 on the end carriage engages a shock-absorbing plunger 211. During the period of rest of the welding conveyer, the cross conveyers are operated. The conveyer 44, Fig. 21, which transfers the carriages from alignment with the welding conveyer to a position in alignment with the loading conveyer after removal of the finished work from the carriage, consists of a pair of chains 167 provided with four pairs of tracks such as 172, 173 and also pairs of cam bars which engage rollers 241 on plungers to lift the completed work off the carriage when the carriage runs on to the tracks 172 &c. The work is removed from the carriage by a number of pivoted tongs 245, Fig. 30, which are operated by a handle 250 through rock arms on a shaft 246 and rods 249 carried by a member 243 suspended from a bar 244. The bar is connected at opposite ends by cords 255 passing over pulleys 256 to a piston 253 controlled by a manuallyoperated valve 254 so as to raise the work from the carriage. The unloading device is suspended from a track 258 and may be transported to the point of distribution. When the unloading of the carriage is completed, a switch 342 in the circuit of a solenoid-operated valve is closed so as to start the movement of the conveyer 44. The chains 167 are driven from a shaft 170 connected by a chain 194 to a shaft 187 provided with a gear 186 in mesh with a gear 185 on a shaft 182 driven through a pinion 181 by. a rack 179 reciprocated by a fluid pressure cylinder 177 controlled by a pair of solenoid-operated valves. The gear 185 is connected to the shaft 182 by a uni-directional clutch consisting of a spring-pressed member engaging a cam groove in the hub of the gear. The conveyer is braked by spring-pressed arms 224 carrying shoes engaging a drum on the shaft 169. The upper ends of the arms carry pistons slidable in a cylinder controlled by a solenoid-operated valve so that the arms may be retracted at the appropriate time by fluid pressure. The position of the carriage in alignment with the loading conveyer is determined by a pair of spring-pressed latch levers 233 engaging the tracks 173 &c. on the chains 167. The latch levers are withdrawn at the appropriate time by fluid-operated pistons controlled by the solenoid-operated valve which controls the brake 224. The loading conveyer on which the work may be mounted on the carriages during traverse thereof consists of a pair of chains 260, 270, Fig. 6. The chain 260 has dogs 267 engaging projections depending from the rear ends of the carriages and is driven direct from the shaft 263 which is driven by reduction and sprocket gear from an electric motor. The carriage is advanced thereby until it assumes a position at the delivery end of the conveyer. The carriage is moved on to the transfer conveyer 41 by the chain 270 which is driven from the shaft 263 through shaft 273 and chain 276. Dogs on this chain 270 engage the forward ends of the carriages and push them on to the track of the conveyer 41. The operation of the loading conveyer is electrically controlled by the carriage on the welding conveyer in registration with the first welding station 46. The con. veyer 41 is operated in a similar manner to the conveyer 44. When the carriages on the conveyers 41, 44 reach the end of their movements they close switches in series with each other and with a switch which is closed by the carriages when they are lowered on to the track of the welding conveyer. Traverse of the carriages along the welding conveyer is not effected until these switches are all closed. Safety circuits with switches are also provided.