WORK BALANCE APPROACH

WORK BALANCE This chapter introduces the work or energy balance which is a very simple method of estimating the work and energy involved in some metal forming operations. It does not however permits predictions of the resulting properties. The energy to complete an operation can be divided into ideal work w i, that would be required for the shape change in the absence of friction and inhomogeneous flow, the work against friction w f, and the redundant work w r. IDEAL WORK

EXTRUSION AND DRAWING Extrusion process

Rod or wire drawing

MAXIMUM DRAWING REDUCTION The most frequently used invariant function to describe plastic deformation is effective stress or effective strain. It is useful to define an effective stress for a yield criterion such that yielding occurs when the magnitude of effective stress reaches a critical value.

EFFECTS OF DIE ANGLE AND REDUCTION Figure 6.5