Improving of closed die-forging of transport and marine fasteners “wing nut”

Abstract

The “wing nut” is a widespread transport and ship fixture designed to locking of hatches, covers and portholes. A more advanced closed die forging for the “wing nut” forgings of transport fittings was proposed with preforming by new method of bulk buckling of billet with upsetting ratio (height to diameter ratio) of 4.2...4.4. The billet and process calculation were performed based on results of researched and a new die forging was tested on a screw friction press. The results of experimental studies conducted on model lead billets at room temperature, and steel billets heated to 1180 °C, confirmed the increase in the accuracy rate of the billet material utilization ratio (one forging mass to one billet mass ratio) from 0.519 to 0.734 and metal savings up to 41% in comparison with the basic die forging without preforming of billet. It is shown that the introduction of a preforming by bulk buckling operation improves the forgings macrostructure (grainflow) even for cases the initial billets are buckled to folding defect formation, because with the further finishing die forging of semi-finished work-pieces the folding defect is displacing (or extruding) into flash. The improved die forging process and recommendations are accepted for implementation in the industry and the direction of reducing the cost of repair work for transport is noted.