Bending method and single elongation value specifying device of bending apparatus

摘要

A bending apparatus for bending a workpiece W according to cooperation of a punch P and a die D previously carries out various step bending or makes simulation of step bending, and calculates an approximation formula based on a correlation between a ratio % of a one-sided elongation value alpha to a plate thickness t and a step bending angle theta based on a relationship among the plate thickness t, the step bending angle theta and the one-sided elongation value alpha of the workpiece W so as to store the formula as a database. The more accurate one-sided elongation value alpha of the step bending is calculated by small parameters including only two data including the plate thickness t and the step bending angle theta previously input at the time of actual bending based on the approximation formula in the data base so that the bending is carried out easily.