EVALUATION OF THE FORMING LIMIT OF ALUMINUM SQUARE CUPS

Combined effects of process variables (blank shapes, tool shapes, blan k materials and punch lubrication) on the deep-drawability of square c ups were studied. Characteristic force lines to estimate the deep-draw ability were introduced. The combined effects of the process variables were explained based on the force lines, the types of fractured cups and the thickness strain distribution. Moreover, the limiting drawing ratio could be easily evaluated from the force lines. The constant fra cture force and the transitional fracture force were defined. These fo rces were used as the target values for the improvement in the deep-dr awability. The extent of the improvement in the deep-drawability was e valuated using the fracture forces. (C) 1998 Elsevier Science S.A. All rights reserved.