+1 vote
in Machine Dynamics by (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

1 Answer

0 votes
by (38.6k points)
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.

Related questions

We welcome you to Carrieradda QnA with open heart. Our small community of enthusiastic learners are very helpful and supportive. Here on this platform you can ask questions and receive answers from other members of the community. We also monitor posted questions and answers periodically to maintain the quality and integrity of the platform. Hope you will join our beautiful community
...