GB1409215A - Lead battery welding method and apparatus - Google Patents

Abstract

1409215 Lead battery electrode connections GATES RUBBER CO 14 Nov 1973 52883/73 Heading H1B [Also in Division B3] In connecting together lead collector tabs 30 and a lead post 32 of an electric battery cell sub-assembly, the latter is supported in a holder 26 positioned, by guides 24, in a table 12, the tabs 30 and a portion 48 of the post are pushed together by jaws 44, 46 having portions 52, 50 forming mould walls, and the tabs 30 and post portion 48 are fused together using an inert gas-shielded, non-consumable electrode, arc welding torch 18, the arc moving in a sinusoidal or zig-zag path relative to the workpiece, and the mould walls retaining the fused metal and, by heat transfer therethrough, causing solidification from the metal periphery inwards. The cell sub-assembly may comprise parallel plates or, as shown, spirally wound positive and negative lead plates and interleaved porous absorbent separator material, the plates being, e.g., of expanded mesh or foil substrate bearing a bonded layer of electrochemically active lead paste and a plurality of tabs 30, 30<SP>1</SP>. Prior to welding, the tabs and post may be crimped together and cleaned or chemically conditioned. The electrode of the torch 18 is preferably of tungsten or tungsten alloy and the shielding gas may be argon or helium and may have hydrogen or other gas admixed therewith. As shown, the torch is carried by a rectilinearly movable carriage (14). The torch may be transversely oscillatable or the arc may be oscillated magnetically using a non-oscillating head. Preferred oscillating rate is 60-2400 cycles per minute. The head and table may, alternatively, be respectively stationary and movable. The post 32 is positioned by a locator 34 having a pivoted arm 36, an apertured post-receiving portion 38 and, for post retention, a vacuum bonnet connected to a vacuum line 40. After location of the post between one set of tabs 30, the jaws 44, 46 are actuated, e.g. hydraulically or pneumatically, and the locator 34 is then withdrawn, a microswitch actuated by a spring 42 serving to render the welding torch operable only in the fully withdrawn position of the locator. The jaws 44, 46 are of arc-erosionresistant material having adequate electrical and thermal conductivity and a softening point higher than that of lead, such as titanium, tantalum, carbon, steel or copper (water cooled or having a surface layer of tungsten) or preferably tungsten or tungsten alloy (e.g. 2% thorium). One or both of the jaws may serve as a positive or negative counter-electrode. Preferably the current for the torch is relatively high on approach to the workpiece and is reduced for the welding. After welding, the fixture may be turned through 180 degrees in preparation for welding the tabs 30<SP>1</SP> to a post.