GATE 2020 ME (ME2) – Question 32
A bolt head is formed at the end of a 12 mm diameter rod by localized upsetting. Unsupported rod length is 40 mm. To avoid buckling, find the maximum die diameter for closed-die forging (mm).
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: 18 to 19.5
Explanation
The proposed upset length40 mm exceeds3d=36 mm. The usual upset-forging design rule limits the closed-die cavity diameter to1.5d for such long stock, giving1.5×12=**18 mm**. Proper die confinement is essential; the unsupported projection beyond the die must also be limited. Reference: https://msvs2-dei.vlabs.ac.in/exp/preformed-defects/theory.html