In a punching press, the requirement is to punch 40 mm diameter holes in a plate having a thickness of 15 mm. The rate at which the holes should be punched is 30 holes/min. Energy requirement is of 6 N-m per mm2 of sheared area. If the punching takes time 1/10 of a second and the speed of the flywheel varies from 160 to 140 rpm, determine the mass of the flywheel having radius of gyration of 1 m.

Question

In a punching press, the requirement is to punch 40 mm diameter holes in a plate having a thickness of 15 mm. The rate at which the holes should be punched is 30 holes/min. Energy requirement is of 6 N-m per mm2 of sheared area. If the punching takes time 1/10 of a second and the speed of the flywheel varies from 160 to 140 rpm, determine the mass of the flywheel having radius of gyration of 1 m.

asked Sep 22, 2022 in Machine Dynamics by Grayson (34.3k points)

In a punching press, the requirement is to punch 40 mm diameter holes in a plate having a thickness of 15 mm. The rate at which the holes should be punched is 30 holes/min. Energy requirement is of 6 N-m per mm2 of sheared area. If the punching takes time 1/10 of a second and the speed of the flywheel varies from 160 to 140 rpm, determine the mass of the flywheel having radius of gyration of 1 m.

(a) 327 Kg

(b) 654 Kg

(c) 163.5 Kg

(d) 200 Kg

The question was posed to me during an online interview.

This question is from Flywheel in a Punching Press in portion Turning Moment Diagrams and Flywheel of Machine Dynamics

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Fred · Answer 1 · 2022-10-14T18:05:49+0000

Correct choice is (a) 327 Kg

Explanation: N = (160+140)/2 = 150 rpm

E1 = 11 310 N-m (A x Shear force)

E2 = 565.5 N-m (energy supplied by motor in 1/10 of a second)

ΔE = 10744.5 N-m

therefore m = 327 Kg.

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