A press machine is required to punch out discs of 40 mm diameter from steel plate 1.5 mm thick with a shear strength of 200 MPa. Calculate the compressive strength in the punch.?

1 Answer
A08
May 15, 2018

It is assumed that we are required to calculate #sf"compressive stress"# in the punch.

We know that Punch force is the product of shear strength of the metal plate and the cross-sectional area #A_s# which is required to be sheared.
slideplayer.com/slide/6035100/
As seen from the above figure #land t# are the perimeter and thickness respectively of disc which is to be sheared.

Alternatively, average shear stress in the plate

#tau_"ave"=F/A_s#
where #F# is punch force.

Inserting given values we get

#200=F/(pixx40xx1.5)#
#=>F=200xxpixx40xx1.5\ Mpa*mm^2#
#=>F=12000pi\ Mpa*mm^2#

Average compressive stress in the punch

#sigma_c=F/A_"Punch"#

Inserting given values we get

#sigma_c=(12000pi)/(pixx40^2/4)#
#=>sigma_c=30\ Mpa#

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