| 摘要 |
PURPOSE:To prevent any stress concentration from occurring before it happens, by moving the brushlike tool made up of bundling plural flexible wire rods containing abrasive grains along the plane surface of a cutting plate spring blank, and rounding the outer circumference. CONSTITUTION:For example, in the case of manufacture of an armature supporter of a printing head, first etching treatment is applied to an almost squre sheet blank with springingness, and it is cut into armature supporter form. In this cut plate 46, projecting parts 24 still remain in a peripheral edge of a part corresponding to a torsion bar 22 or the like, so that it is arranged on a table 41 and fixed thereon by magnetic force, making a brush unit 42 go down, and this brush unit 42 is rotated in both c.w. and c.c.w. directions as long as the specified time at the specified speed, then these projecting parts 45 are shaved off by each brush piece 43, and afterward, the plate 46 is turned over, shaving off the other side of projecting parts 45, thus the peripheral edge is rounded. Doing like this, stress concentration is obviated, while the occurrence of any dent caused by a collision of blanks themselves is preventable and, what is more, improvement in durability is well promoted. |
