Cold Forging of Rivet Shape Head from Cylindrical Porous Aluminum Specimen at Different Strain Rates

The paper presents an investigation into the problem of shape heading under low-velocity dynamic forging conditions where the initially circular aluminum powder porous specimen clamped at one of its ends, is headed into a circular shaped head rivet. Yield criterion, friction law, chosen velocity field an upper bound approach have been considered to develop a mathematical model for the relative average forging pressure on the specimen at different strain rate. The specimens were prepared and subjected to rivet head forging process at different strain rates: 1.5, 50, 100 and 150 mm/min under lubricated end conditions. Parametric analysis giving the variation of the relative average forging pressure versus percentage reduction in height of the specimen during rivet head forging process was presented graphically. Theoretically and experimentally obtained values of forging load versus percentage reduction in height of the specimen during the process were plotted and a good correlation was observed. Strain rate effect on forging load during circular rivet head forming process versus percentage reduction in height were presented graphically, analyzed and discussed critically.