| 摘要 |
PURPOSE:To eliminate shortage of strength in connections by forming and combining a conical boss integrally with the base of blades. CONSTITUTION:A conical boss 11 is provided with notches 14 at portions concealed by blades 13 as viewed from the front, so that the conical boss 11 and the respective blades 13 can be molded integrally by an injection molding means for plastics. Also, since the conical boss 11 and the respective blades 13 have smooth surfaces and are connected integrally with each other, the connections between the boss and blades are neither short of strength nor broken. |
