TABLE OF CONTENTS Blanking punches range from tiny components for producing watch and instrument parts to large, multi-unit members for blanking such parts as automobile fenders, doors, and tops. The size of the blank to be produced determines the type of punch to use. Design considerations include:
Stability, to prevent deflection.
Adequate screws, to overcome stripping load.
Good doweling practice, for accurate location.
Sectioning, if required, for proper heat treatment.
Illustrations that follow show numerous methods of applying blanking punches to small, medium, and large cutting dies. Several considerations are covered, such as keying the punch in order to keep it from turning, use of inserts for ease and economy of replacement, use of sectioning to facilitate heat-treating and minimize distortion, use of shedders to prevent clinging of blanks to punch faces, and proper proportions of and construction of blanking punches. These methods further explain Step 3 in Chapter 5 Fourteen Steps to Design a Die.
Figure 8.1 shows the method of applying a blanking punch for small instrument washers.
Body diameter A is made considerably larger than blanking diameter B; radius C provides supporting material to give rigidity and prevent deflection of the punch upon contact with the material strip. Section view a shows the punch, punch plate, and punch holder as they would appear in the lower left section view of the complete die drawing. Plan...
