Question

A strip of thickness 40 mm is to be rolled to a thickness of 20 mm using a two-high mill having rolls of diameter 200 mm. Coefficient of friction and arc length in mm, respectively are

Options :

  1. 0.45 and 38.84

  2. 0.39 and 38.84

  3. 0.39 and 44.72

  4. 0.45 and 44.72

Show Answer

Answer :

0.45 and 44.72

Solution :

Given, hi = 40 mm, hf = 20 mm, D = 200 mm

R = D 2 = 100   m m

Δh = hi - hf

Δh = 20 mm

Projected length,  L = R   Δ   h

L =   100 × 20

⇒ L = 44.7213 mm

∵ Δh = μ2R

μ =   Δ   h R = 20 100

∴ μ = 0.4472

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