1- A blanking operation is to be performed on 2.0 mm thick cold-rolled steel (half hard). The
part is circular with diameter = 75.0 mm.
a. Determine the appropriate punch and die sizes for this operation.
b. Determine the blanking force required if the shear strength of the steel = 325 MPa
and the tensile strength is 450 MPa
c. What safety precautions should be taken during this manufacturing process.
2- A 3.0-in long cylindrical billet whose diameter = 1.7 in is reduced by indirect
extrusion to a diameter = 0.4 in. Die angle = 90°. In the Johnson equation, a = 0.6 and
b = 1.8. In the flow curve for the work metal, K = 80,000 lb/in2 and n = 0.2.
Determine:
(a) extrusion ratio,
(b) true strain (homogeneous deformation),
(c) extrusion strain,
(d) ram pressure,
(e) ram force, and
(f) power if the ram speed = 23 in/min.
3- A 42.0-mm-thick plate made of low carbon steel is to be reduced to 34.0 mm in one
pass in a rolling operation. As the thickness is reduced, the plate widens by 4%. The
yield strength of the steel plate is 174 MPa and the tensile strength is 290 MPa. The
entrance speed of the plate is 15.0 m/min. The roll radius is 325 mm, and the
rotational speed is 49.0 rev/min. Determine:
(a) the minimum required coefficient of friction that would make this rolling
operation possible,
(b) exit velocity of the plate,
(c) forward slip.
4- In hydrostatic extrusion, complex seals are used between the ram and the
container, but not between the extrusion and the die. Explain why?
5- Name three process variables in drawing.
6- Describe the differences between compound, progressive and transfer
dies used for shearing sheet metal.
7- A hot upset forging operation is performed in an open die. The initial size of the workpart is:
Do = 25 mm, and ho = 50 mm. The part is upset to a diameter = 50 mm. The work metal at this
elevated temperature yields at 85 MPa (n = 0). Coefficient of friction at the die-work interface
= 0.40. Determine
(a) final height of the part,
(b) maximum force in the operation
1- Define the following for sheet metal bending processes:
a. Bend allowance
b. Spring back