To omit a chamfering work and to reduce the production cost by displaying automatically a round slight chamfer at a rectangular shape part that is included in a chart consisting of ruled lines.
A 2nd rectangular shape part 68 is identified and stored among the ruled lines forming a chart, and the coordinates of a 1st end point 24 of the part 68 are calculated and stored. Then, the numerical value is set for a 1st round slight chamfer 25 which is drawn at the part 68, and a line is drawn so that all parts 68 are made tangent to each other at the chamfer 25. The straight lines 32 and 33 set closer to the point 24 than the contacts 34 and 35 set to the chamfer 25 are deleted out of the lines of the part 68. Thus, the chamfer 25 can be automatically displayed at all rectangular parts 68 included in the ruled lines forming a chart.
TAKAGI KENICHI
FUKUTOME SHIGEKI
