Patent GB-544047-A (GB)
Title: An improved method of, and machine for, welding
IPC: B23K11/00
Filed: 1940-08-23
Abstract: 544,047. Welding motor-vehicle frames &c. BUDD MANUFACTURING CO., E. G. Aug. 23, 1940, No. 13370. [Classes 83 (ii) and 83 (iv)] An electrical multiple spot welding machine such as is described in Specifications 504,505 and 507,198 for producing sheet metal boxsection beams for automobile chassis, is constructed with means for effecting an initial welding of the cover plate 30 to the flanged channel member 32 in a manner which is similar to that described in the above Specifications, and the work is completed in a number of machines termed re-welders in which no hydraulic pressure is applied to the partially welded members, and in which the article is inverted so as to enable the welding guns to come into operative position more readily and by the lateral movement of one table only instead of employing two tables 94, 96, Fig. 6, which are both moved laterally by fluid pressure to enable the channel section member 32 to be placed on a number of support members 58 prior to the first welding operation. Prior to the operation of the welding devices the cover plate 30, which is clamped to a press ram 40, after being registered in position by pins and holes, is moved into contact with the member 32 by operation of a lever 298, which controls a valve 286 controlling the supply of liquid to the press cylinder 46. Shaped members are carried by the ram 40 to cause the cover 30 to conform to the shape of the member 32. As the ram completes its descent a cam 306 carried thereby operates a valve to connect fluid pressure to cylinders 120 which operate pistons 122 and adjustable lever mechanism to move the tables 94, 96 inwards so as to cause the welding guns to come into operative position. Also another projection operates a switch 319 which energizes a motor 210 which operates Geneva gear for imparting intermittent step-by-step motion to cam shafts 228, 230, 232, 234, which operate valves for controlling the fluid pressure in cylinders which bring the welding electrodes into contact with the cover plate 30 and flange of the member 32. The welding guns 90, 92 are supported on shaped support blocks 98, 100, 102 so as to conform to the curvature of the section 32, and the tables 94, 96 are mounted on rollers moving on guide rails, and carry bus bars 190, 192 connected by flexible leads to four pairs of transformers 204 each pair associated with a number of guns 90, 92. There are six guns in each section, and these each are made to engage the work in sequence. The action of the electrodes 618 and the manner of pressing them in contact with the flanges is shown in Fig. 23 as applied to the re-welding apparatus, and both electrodes are adapted to engage the work under substantially equal fluid pressure. The lower electrode is insulatedly mounted in the top of a cylinder 610 capable of moving in guides attached to a bracket 600, and the upper electrode is mounted in a yoke which is depressed by the piston 632 when fluid is admitted to the upper end of the cylinder through the bore 672 of the piston rod, the cylinder 610 acting to raise the lower electrode at substantially the same time. On account of the floating movement of the cylinder and piston flexible hoses 680, 682 are used. The upper electrode is water-cooled and a shield 674 prevents sparks of metal from doing injury. The cam shaft 228 is fitted with a cam which operates a switch to stop the driving-motor when a series of welds has been effected, and at the same time the valve for controlling the press ram is reversed in order to raise the ram and allow the partly finished work to be removed for transfer to the re-welding appliances. Fluid-operated ejectors assist this transfer. The re-welders are adapted to act upon portions of the flanges not acted upon by the pressing and welding apparatus described, and is especially designed to apply extra spot welds along concave portions of the work piece which received less spots than the convex portions during the first operation. The construction and manner of operation of the re-welders is substantially the same as the press welder described.