TABLE OF CONTENTS This part discusses the methods that are most used for sheet metal forming. The text is presented in five chapters, which deal, in detail, with: shearing, punching and blanking, bending, deep drawing, and various forming processes (stretching, nosing, expanding, flanging, flexible die forming, and spinning). Special attention is given to the mechanism of processes, estimation of forces, clearances, minimum bend radius, and other important factors in sheet-metal forming processes. Detailed analytical mathematical transformations are not included, but the final formulas derived from them, which are necessary in practical applications, are included.
The shearing process involves the cutting of flat material forms, such as sheets and plates. The cutting may be done by different types of blades or cutters in special machines driven by mechanical, hydraulic, or pneumatic power. Generally the operations consist of holding the stock rigidly, while it is severed by the force of an upper blade as it moves down past the stationary lower blade.
During the shearing process, three phases may be noted: In phase I, because of the action of the cutting force F, the stress on the material is lower than the yield stress ( ? < ? e). This phase is that of elastic deformation (Fig. 3.1). To prevent the movement of material during the cutting operation, the material is held by...
