Sheet metal Forming BY RAVI SINGH CHOUDHARY
GATE syllabus Load estimation for Sheet metal forming process Shearing: Blanking & Punching Deep drawing Bending
Blanking and Punching Shearing force lit Shearing force (circular hole) = dtt
Determine the die and punch sizes for blanking a circular disk of 20mm diameter from a C20 Steel sheet whose thickness is 1.5mm. (Shear strength of annealed C20 steel is 294 MPa Solution: C 0.0032*t* 0.0032*1.5*V294-0.082 3mm Since it is blanking operation: Die size = Blank size = 20mm Punch size Blank size-2C = 20-2*0.0823 = 1 Punching force dtt = 3.14*20*1.5*294 = 27.71 kN
Blanking Punch diameter= Die diameter-2C Diameter of die Diameter of blank Clearance should be on punch
Shear on punch It distribute the cutting action over a period of time Shear only reduces the maximum force to be applied but Work done(with shear) = F(kt+1) work done = Fmax(kt) Total work done remains same.
Shear on punch ma LtT s shear on punch %penetration
End of session Thank ou