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amilapsn
 one year ago
A punching machine has to carry out piercing operations at the rate of 12 holes per minute. The amount of work to be done in cutting 30mm diameter holes in 15mm thick plate is 8J/mm2 of the sheared area. The actual piercing operation takes 2s. The total frictional losses over a cycle are equivalent to one sixth of the work done during a single piercing operation. The machine shaft is driven by a constant power electric motor. The maximum fluctuation of the speed of the machine shaft is between 190 rev/min and 210 rev/min.
(a) Find the minimum required motor power to drive the piercing machine
amilapsn
 one year ago
A punching machine has to carry out piercing operations at the rate of 12 holes per minute. The amount of work to be done in cutting 30mm diameter holes in 15mm thick plate is 8J/mm2 of the sheared area. The actual piercing operation takes 2s. The total frictional losses over a cycle are equivalent to one sixth of the work done during a single piercing operation. The machine shaft is driven by a constant power electric motor. The maximum fluctuation of the speed of the machine shaft is between 190 rev/min and 210 rev/min. (a) Find the minimum required motor power to drive the piercing machine

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amilapsn
 one year ago
Best ResponseYou've already chosen the best response.1(b) Determine the required sum of the mass moments of inertia of all revolving parts on the machine shaft in order to keep the speed fluctuation within the given limits. State any assumption made.

amilapsn
 one year ago
Best ResponseYou've already chosen the best response.1I've got some problems to sort out regarding this problem @dan815

dan815
 one year ago
Best ResponseYou've already chosen the best response.0okay what seems to be the problem

amilapsn
 one year ago
Best ResponseYou've already chosen the best response.1During a piercing operation the shear area would be \(\pi r^2\) or \(s2\pi r h\) where r is the diameter of the hole while h is the depth...

amilapsn
 one year ago
Best ResponseYou've already chosen the best response.1Then why the depth is given?

dan815
 one year ago
Best ResponseYou've already chosen the best response.0not sure why, i dont think we need it

dan815
 one year ago
Best ResponseYou've already chosen the best response.0it gives work per surface area though in mm^2 so

amilapsn
 one year ago
Best ResponseYou've already chosen the best response.1Work done per hole = 8 x pi x r^2?

amilapsn
 one year ago
Best ResponseYou've already chosen the best response.1Am I right: minimum power to drive the piercing machine=maximum power in a cycle

amilapsn
 one year ago
Best ResponseYou've already chosen the best response.1dw:1433649727575:dw

amilapsn
 one year ago
Best ResponseYou've already chosen the best response.1But in a text book they've taken the average as the minimum required power...

IrishBoy123
 one year ago
Best ResponseYou've already chosen the best response.1you need the thickness in shear area Ex 5 on page 10: http://www.freestudy.co.uk/mech%20prin%20h2/stress.pdf

amilapsn
 one year ago
Best ResponseYou've already chosen the best response.1Thank you so much! @IrishBoy123
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