GB1503988A - Method of manufacturing the arms for hand-operated tongs or pliers - Google Patents

Abstract

1503988 Making hand tools KOMBINAT UMFORMTECHNIK HERBERT WARNKE ERFURT VEB 28 April 1975 [29 April 1974] 17458/75 Heading B3A Steel arms for pliers or tongs are made by compacting metal powder to form an initial workpiece, Figs. 1 and 2, with square edges, a straight handle 3 and a minimum density of 60% of that theoretically possible, heating the initial workpiece to 1000-1200‹ C. in protective gas and drop-forging it to intermediate form, Fig. 3, in a closed die which maintains the square edges while increasing the density to 98-100% without there being any flow between adjacent parts of different thickness, and subsequently hot or cold stamping the handle 3 in a divided tool to curve it longitudinally, Fig. 6, and round the cross-section. If the intermediate blank is to be cold-stamped this operation may be preceded by a cutting operation, annealing, cleaning, sand-blasting, tumbling, polishing and electro-chemical grinding. If the intermediate blank is to be hot-stamped, residual heat of the forging operation may be used or the blank may be heated to 650‹C. A graded powder may be used to form the compact, the powder for the jaw part, including 0À5-0À6% C while that of the rest of the handle may include small additions of graphite. Zinc stearate may be included as a lubricant.