Patent GB-803125-A (GB)
Title: Resistance welded joint and method and apparatus for producing same
Inventor: COFFEY RALPH J
IPC: B21L11/14
Filed: 1956-04-24
Abstract: 803,125. Welding by pressure. AMERICAN CHAIN & CABLE CO., Inc. April 24, 1956, No. 12585/56. Class 83 (4).  In resistance welding two elements by holding the elements against relative outward or lateral movement in spaced relationship, a slug of metal too large to fit the space between the elements is placed on one side of the elements and pressure is applied to force the slug between the elements while current is passed through the slug. A chain link 30, Fig. 1, with spaced ends 30a, 30b, is fixed in a holder and two blunt wedge-shaped slugs 33, Figs. 1, 2, are forced by electrodes 34, into which the slugs may be clipped, towards one another with current flowing through the slugs until they touch. In a modification a stud may be provided in the link by a cylindrical extension welded at one end to the slugs at the time of welding the slugs and the other end may be left unwelded. Chain links of carbon steel, 18-8 titanium stabilized stainless steel, 16 chromium, 25 nickel, 6 molybdenum alloy steel and 8 per cent aluminium bronze may be welded. Flat plates 38, Fig. 8, are held apart and T-section rods 40 are pressed into the gap by roller electrodes to form the characteristic " hour-glass " weld in section. A stud chain link may be formed by employing two slugs each having an end portion 105, Fig. 22, and an extension 106, the end portion being half round and notched at 105a to provide a wedge-shaped area 105b, Fig. 23 and the extension being bevelled to engage the opposite side of the link. The slugs are welded into the link as previously described and the extension may be welded to the opposite side of the link at the same time or may be spot or tack welded subsequently. An apparatus for forming such stud links comprises a lower electrode 50, Fig. 11, mounted on an insulating block 48 on a frame 44, the upper surface of the electrode being shaped to receive a stud slug 52, and an upper electrode 76 carried on an insulating block 74 secured to a vertically guided head 66 on the end of a piston-rod 60 of a pneumatic cylinder 57. The lower surface of the electrode 76 is shaped to receive a slug 78 and leaf-springs 80, Fig. 12, are provided to grip the slug. A bifurcated arm 85 of a clamp 82 for chain link is pivoted at 86 between bars 83 secured to the frame. An arm 88 extends from a cross-piece 87, Fig. 14, joining the arms 85 and a movable arm 90 is pivoted at 91 to the cross-piece 87 being held in a position parallel with the arm 88 by a latch arm 92 pivoted at 93 to the arm 90 and engaging the arm 88. A spring 94 between the arm 90 and the latch 92 urges the latch into its latched position and a spring 96 connected between a hook 97 on the latch arm and a hook 97 on a fixed bracket 64 partially counterbalances the weight of the clamp. Slots 88a, 90a and semicircular recesses 88b, 90b are cut in the arms 88, 90 to receive adjacent links of a chain. In operation with two stud type slugs in the electrodes the link to be welded is secured in the clamp, the piston-rod 60 is moved downwardly until the upper electrode slug engages the link. The current is switched on and pressure is built up until the slugs meet when current is switched off, the upper electrode is withdrawn and the clamp is manually unlatched to release the welded link. The chain is rotated through 90 degrees and the next link is secured in position.