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A strip of 120 mm width and 8 mm thickness is rolled between two 300 mm diameter rolls to get a strip of 120 mm width and 7.2 mm thickness. The speed of the strip at the exit is 30 m/min. There is no front or back tension. Assuming uniform roll pressure of 200 MPa in the roll bite and 100% mechanical efficiency, the minimum total power (in kW) required to drive the two rolls is _______.
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- 91.34 kW
- 19.33 kW
- 3.34 kW
- 9.34 kW
Correct Option: D
Velocity of Neutral plane
By applying continuity Equation
Hn = H2 + 0.25∆H
Hn = 7.2 + 0.25 × 0.8 = 7.4 mm
VnHn = V2H2
V2 → Exit velocity
H2 → Final Height
Vn = 29.19 m/min
| Vn = | ||
| 60 |
| N = | = 30.98 rpm | |
| π × 300 |
Total power = 2Tω
| Total power = 2 × 1439.9 × 2π × | = 9.34 kW | |
| 60 |
