GATE PI concept:rolling PYQs & Answers

Questions 1–8 of 8. Imported answers require independent review unless marked reviewed.

Which ONE or MORE among the following options CORRECTLY match(es) the type of defects with the corresponding metal working processes in which they are likely to occur?

Defect	Process
P: Centerburst	1: Deep drawing
Q: Earing	2: Rolling
R: Zipper cracks	3: Extrusion
S: Cold shut	4: Closed die forging
	5: Casting

Your answerSelect all correct options. You can choose more than one.

P-3; Q-1; R-2; S-4

P-5; Q-2; R-3; S-4

P-1; Q-2; R-4; S-5

P-3; Q-1; R-2; S-5

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In a rolling operation, a 200 mm wide strip of 23 mm thickness needs to be reduced to 20 mm in a single pass. The roll diameter is 200 mm. Four lubricants P, Q, R, and S with coefficient of friction 0.05, 0.1, 0.2, and 0.25, respectively, are available for use at the roll-strip interface. Assume that the strip width remains constant throughout the process.

Which ONE or MORE among the following lubricants will enable the rolling process to achieve the desired final thickness of the strip in a single pass?

Your answerSelect all correct options. You can choose more than one.

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In a cold rolling process without front and back tensions, the required minimum coefficient of friction is 0.04. Assume large rolls. If the draft is doubled and roll diameters are halved, then the required minimum coefficient of friction is________. (Rounded off to two decimal places)

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In a single pass cold rolling operation, a flat plate is reduced to a thickness of 3 mm. In this operation, two rolls of diameter 400 mm each are rotating in opposite direction at 300 RPM, and the elastic deflection of these rolls is negligible. The angle of bite is 10°. If the neutral point is present at an angle of 7° from the exit side, then the thickness of the plate (in mm) at the neutral point is ________. (Rounded off to 1 decimal place)

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Match the products to be manufactured with the given metal working processes.

Product: P—Beverage can; Q—Seamless pipe; R—Connecting rod; S—Steel balls for bearing.

Process: 1—Forging; 2—Skew Rolling; 3—Extrusion; 4—Deep Drawing.

Your answerChoose one option.

P – 3, Q – 4, R – 1, S – 2

P – 2, Q – 4, R – 1, S – 3

P – 4, Q – 3, R – 2, S – 1

P – 4, Q – 3, R – 1, S – 2

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A 3.5 mm thick sheet is rolled using a two high rolling mill to reduce the thickness under plane strain condition. Both rolls have a diameter of 500 mm and are rotating at 200 RPM. The coefficient of friction at the sheet and roll interface is 0.08, and the elastic deflection of the rolls is negligible. If the mean flow strength of the sheet material is 400 MPa, then the minimum possible thickness (in mm) of sheet that can be produced in a single pass is ________. [round off to 2 decimal places]

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A 10 mm thick plate is rolled to 7 mm thickness in a rolling mill using 1000 mm diameter rigid rolls. The neutral point is located at an angle of 0.3 times the bite angle from the exit. The thickness (in mm, up to two decimal places) of the plate at the neutral point is _____

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A metallic strip having a thickness of 12 mm is to be rolled using two steel rolls, each of 800 mm diameter. It is assumed that there is no change in width of the strip during rolling. In order to achieve 10% reduction in cross-sectional area of the strip after rolling, the angle subtended (in degrees) by the deformation zone at the center of the roll is

Your answerChoose one option.

1.84

3.14

6.84

8.23

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GATE PI concept:rolling PYQs

How to practice concept:rolling

Question 26

Question 46

Question 46

Question 53

Question 43

Question 55

Question 49

Question 47