A cylindrical part is upset-forged in an open die. Height after forging = 20 mm. The starting diameter = 50 mm and height = 30 mm. Coefficient of friction at the die-work interface = 0.20. Yield strength of the low-carbon steel = 120 MPa; its strength coefficient = 575 MPa and strain-hardening exponent=0.21.
Determine the force in the operation
(a) just as the yield point is reached (yield at true strain = 0.002).
(b) at a height of 25 mm,
(c) at a height of 20 mm. Use of a spreadsheet is recommended.