GB1474885A - Manufacture of forks for fork lift trucks - Google Patents

Abstract

1474885 Making forks for fork lift trucks; welding by fusion LANCER BOSS Ltd 21 June 1974 [17 July 1973 9 Oct 1973] 34054/73 and 51742/73 Headings B3A and B3R A method of producing fork lift truck forks of L-shaped construction from rolled steel strip sections comprises providing two arm portions 13, 14 from strip having the cross-section of the desired fork, disposing the ends 15 of the two arm portions in contiguous mutually perpendicular relationship with an air gap between them, masking the gap to form an enclosed cavity, introducing into the cavity one or more welding guides 23, passing welding wire 24 through each guide into the cavity, passing a high frequency electric current through each wire and/or guide to produce a weld, and subsequently normalizing and tempering the metal of the formed fork. The welding operation includes fixing the portions 13, 14 in clamps with their mitred ends 15 parallel to each other. Melt retaining shoes 19, 20 are clamped to the portions and a plate (40), Fig. 3 (not shown), is placed on one side of the portions to provide a weld cavity. Tubular guides 23 of weldable material are passed through apertures between blocks (41) and include welding wires 24, e.g. of EN24 steel. The shoes are cooled by a cooling fluid in ducts 21 and have spaces 22 for the weld flash. In an embodiment, Fig. 4, the guide comprises a plurality of rods 42 which form a channel for passage of a welding wire 43. Suitable wire and guide materials are (a) 2“ Cr-1 Mo or 1“ Cr-¢ Mo wire with a C-Mn steel guide having attached Ni rods, (b) cored wire containing Ni, Cr and Mo additions in the core and a C-Mn steel guide, and (c) C-Mn steel wire with a flux coated C-Mn steel guide, the alloy additions contained in the flux coating. The steel guides can be modified by the attachment of Ni wires to their outside surface, the wires being held in place by a mild steel sheath or by tack welding. When the welding is complete the weld flashes are removed by grinding or milling and the whole fork may be surface finished. Lugs (25), Fig. 1 (not shown), may be welded to the arm portions for connecting to the mast carriage of a fork lift truck. The whole fork may then be heat treated to the required hardness.