3. (a) A tensile sample cut from a piece of sheet metal has an original cross-sectional area of 21 mm². During a tensile

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3 A A Tensile Sample Cut From A Piece Of Sheet Metal Has An Original Cross Sectional Area Of 21 Mm During A Tensile 1 (53.31 KiB) Viewed 52 times

3. (a) A tensile sample cut from a piece of sheet metal has an original cross-sectional area of 21 mm². During a tensile test the maximum load is measured as 3.7 kN at which point the cross-sectional area is 13 mm². A piece of sheet 12 cm long and 2.3 cm wide, of the same material from which the tensile sample was cut, is cold rolled from a thickness of 1.1 mm to 0.79 mm. (i) Calculate the ideal work of deformation for the rolling operation. [6] (ii) Does this calculation underestimate or overestimate the work required? [4] 2 (b) If a different piece of the cold rolled sheet of part (a) is 0.54 m wide and rolled at 6200 cm/min on work rolls of 535 mm diameter, estimate the rolling mill power required for the thickness reduction from 1.1 mm to 0.79 mm. Assume mineral oil is used as a lubricant, giving a friction coefficient of 0.1. [10] (c) If it is desired to reduce the power required for the rolling operation of part (b), what modifications to the process can be made? (The dimensions of the initial and final rolled sheet cannot be altered.) [10] END