Patent GB-899526-A (GB)
Title: Improvements in and relating to stud welding machines
Inventor: ADAMSON PERCY
IPC: B23K9/20
Filed: 1957-08-20
Abstract: 899,526. Making finned tubes; welding by pressure. BABCOCK & WILCOX Ltd. Sept. 26, 1958 [Aug. 20, 1957], No. 26240/57. Classes 83 (2) and 83 (4). [Also in Groups XIII and XXX] A machine for electrically welding a succession of studs 2 to a surface, includes means for moving a stud holder to and fro between a studloading station and a stud welding station which comprises a carriage arranged for reciprocating movement towards and away from the surface to be studded and on which. the stud holder is rotatably reciprocably mounted and means for conversion of linear movement of the carriage during reciprocation thereof into rotary reciprocating movement of the stud holder with respect to the carriage, the stud holder being in one extreme angular position when at the stud loading station and in the other extreme angular position when at the welding station, feeding means for supplying a succession of studs from a stud reservoir and dispensing means to receive studs from the feeding means and to supply a stud to the stud holder each time the holder moves to the loading station. In an embodiment, flat square studs 2 are resistance welded in groups of six about the circumference of a tube 1, adjacent groups being staggered. The tube extends horizontally between two parts A, B, Fig. 4, of the machine which weld two studs simultaneously on opposite sides of the tube, the tube being rotated and moved longitudinally to present fresh surfaces for studding. The studs are fed to the parts A, B by feed channels 8 leading from reservoirs 6 of loose studs. The tube passes through a support 9, Figs. 6 and 7, mounted on a table 10 and having ball castors 11 and the machine A on one side of the tube comprises a carriage having a U frame 14 with limbs 15 slidable in slideway 22 on the table and providing bearings for journals 24 at the ends of a rotatable two-part brass drum 25 carrying a stud holder 12. The piston of a pneumatic cylinder 41 mounted on the table is connected to a shaft 42 extending through the transverse member 23 of the U frame to engage a thrust block 43 having a brass contact piece 44 with two arms 45, 47 shaped to engage the parts of the drum. Forward movement of the carriage is effected by engagement of the arms with the drum and withdrawal by engagement of the thrust block with the member 23 of the frame. The rear drum part 27 is formed with a recess 28, Fig. 10, in which is provided a pin 29 carrying a lever 30 pivoted on a pin 31 mounted on the table. The arrangement is such that when the carriage is in its retracted position the stud holder extends upright above the drum as shown in Fig. 10 and when the carriage is in its forward position the drum is rotated to project the holder towards the tube. Stops on the drum ensure that the drum is brought to rest as soon as the holder is in its desired position and a spring-loaded brake acts on the drum. The holder 12 is a box-like structure formed by electrode parts 61 and 62, Fig. 14, and is arranged in a channel 63 extending through the drum. A stud is gripped therein by a grip 64 pinned to a link 66 pivoted to a point intermediate the ends of a lever 68, Fig. 13, extending across the channel 63, pivoted at 71 to the drum and extending out of the drum. The lever 68 is spring urged for inward movement of the grip 64 so that due to coacting sloping faces of the part 61 and the grip, the grip moves inwardly to hold the stud. A spring 83 urges the grip away from the stud when the lever 68 is moved for outward movement of the stud. The end of the lever 68 projecting from the drum lies, when the carriage is in its retracted position, between the arms 45, 47 with a screw 89 thereon bearing against a stop 90 on one of the arms so that the grip is in its outermost position. The reservoir 6, a circular flat bottomed dish rigidly secured to the top of an electro-magnetic vibrator for vibrating the dish helically so that studs move anticlockwise around a track which rises from the dish floor to an outlet at the level of the rim of the dish. The studs are all fed end faces first and are delivered to a slideway having a portion 162, Fig. 35, above the position occupied by the holder when the carriage is in the retracted position. The engagement of the holder 12 with a spring-operated retainer 172 allows a stud to enter the holder and when the holder moves away the retainer holds the next stud. A similar machine is provided on the other side of the tube. Conductors lead to the contacts on the thrust members from a transformer so that when the studs are pressed against the tube, current passes from one to the other. The tube is moved rearwardly and rotated by a transporter 186, Fig. 40, on rails having an electro-pneumatically rotated chuck 194 for holding the tube. The transporter is moved longitudinally by a rack moved by electro-pneumatic means and an additional support trolley may be provided for the tube. In operation the cylinders of the machine parts A, B are supplied simultaneously with pneumatic pressure and as the carriages advance the drums are rotated. On rotation of the drum the lever 68 moves under its spring pressure to clamp the stud and then the stud is presented to the tube. The studs are resistance welded to the tube and then the carriages are retracted and the drums rotate so that the stud holders are positioned beneath the reservoirs when the lowermost studs drop into the holders. The stud holder electrodes may be liquid jet cooled. According to the Provisional Specification the studs may be cylindrical.