Patent ID: 6456957
Filing Date: 2002-09-24
Classification: B21D

Abstract:
A method for determining a heating line in the bending of a steel plate, comprising:determining the number of a plurality of congruent isosceles triangles, which are connected together while sharing their equal sides, on the basis of the radius of a curve of a target shape of the steel plate to be bent, the radius of a curve of a measured shape of the steel plate, and a separately set bending angle of the steel plate so that when the curve of the target shape of the steel plate is regarded as an arc, the arc of the target shape of the steel plate can be approximated by a fold line defined by the bases of the plural congruent isosceles triangles and that when the curve of the measured shape of the steel plate is regarded as an arc, the arc of the measured shape of the steel plate can be approximated by a fold line defined by the bases of a plurality of other congruent isosceles triangles which are connected together while sharing their equal sides, the number of the latter isosceles triangles being the same as the number of the former isosceles triangles whose bases constitute the approximating fold line for the target shape; dividing the arc of the measured shape by the number of the isosceles triangles to form respective points on the arc; using the respective points as heating points; drawing straight lines from a certain heating point on a certain arc, as a starting point, to heating points on other arcs on the basis of the heating points that have been so determined; examining the degree of parallelism between each of the straight lines and a reference line that is a straight line showing the direction of a central axis of a cylinder provided that the target shape is approximately deemed as a part of the cylinder; if this degree of parallelism is within a predetermined range, performing grouping of the relevant heating points as the heating points of the same group; and connecting the respective heating points of the same group by a straight line or a curve to determine a heating line.