FORMING METHOD OF BOSS PROVIDED WITH CLAMPING BOLT

PURPOSE:To omit a cutting work after forming, and to save a manufacturing cost and a material, by forming a slanting surface connecting a handle part and a projecting part, in a circular arc state, in the process in which the projecting part of a blank is made thicker than the handle part. CONSTITUTION:A plate material is pressed, and a rectangular blank 2 having a circular arc projecting part on both the right and left sides of the upper end is formed. Subsequently, the blank 2 is crushed, the projecting part 1 and a center part 4 except right and left edge parts 3, 3 following the projecting part 1 are made thin, and also a slanting surface 5 connecting the projecting part 1 and the center part 4 is curved in the form of a circular arc. After that, the blank 2 is bend-molded from the right and left by a press bending mold, a cylindrical handle part 6 for pinching the shaft in the center part 4 is formed, and a slit 7 is provided on the upper surface of the handle part 6. Also, to the lower end, a fitting flange 8 formed separately is deposited, and bolt holes for fixing are provided on both the right and left sides of the flange 8. In the end, a screw hole for a clamping bolt 10 is pierced in the right and left projecting parts 1, 1, and on the inside circumference of the handle part 6, notches 12 for turn-stopping are provided.