| 摘要 |
PROBLEM TO BE SOLVED: To improve the biting of y cleaving blade to a blank and to cleave the blank efficiently by setting the angle which is formed with both side faces of the cleaving blade continuously or stepwise smaller as advancing to the edge side of the blade. SOLUTION: Both side faces 21 in the edge part 20a of the blade of the cleaving blade 20 and both side faces 22 in the root part 20b of the blade are respectively composed of linear slopes in the cross sections of partial conical surface shapes. The angle α1 formed with both side faces 21 at the edge part 20a of the blade and angle α2 formed with both side faces 22 at the root part 20b of the blade are composed so as to be α1<α2. When this cleaving blade 20 is used, the biting of the cleaving blade 20 to the blank is maintained in good conditions and cleaved pieces 6A, 7A are outward expanded with both side faces 22 in the root part 20b of the blade, so the angle which is formed with a pair of the cleaved pieces 6A, 7A to be formed can be set larger. Then, spinning for forming a rim part is smoothly executed. Thus, the number of wheel manufacturing processes is reduced. |
