| 摘要 |
PURPOSE:To prevent a crack due to stress concentration by inserting a metallic tube, the inner diameter of which is slightly larger than that of a rotary shaft and having a groove for striking a key therein, into a shaft hole thereof and sticking the tube to a ceramic mold by adhesive. CONSTITUTION:A screw 1 consists of a shaft portion 2, a screw 3 projecting from the shaft portion 2 and a metallic tube 5 stuck to the shaft portion 2 with resin 4, and a rotary body is formed by the screw 1 and a driving shaft 7. A rectangular notch in which a key can be stricken is engraved on the inside surface of the metallic tube 5 long a predetermined length. Further a knurling process is applied on the outer circumference of the metallic tube 5 and the inner circumference of the shaft hole of a ceramic mold: At the time of the rotation of the ceramic rotary body, concentrated stress applied to a key groove from the driving shaft via the key is replaced with shearing stress on the whole inner circumference of the shaft hole of the mold due to provision of the metallic tube and via the adhesive layer so that the stress concentration is eliminated and a defect such as the crack of the ceramic mold does not occur at all. |
