| 摘要 |
PURPOSE:To improve durability of a spiral bimetallic strip by chamfering both angle sections on slit outer end side in a slit press-fitting section of the spiral bimetallic and strip calking a swelling section further in a chamfered section. CONSTITUTION:A spiral bimetallic strip 12 has a rectangular cross section, and chamfering 121 of 5-30 degrees is applied to both angle sections on the slit outer end side of a slit press-fitting section 12a at its outer end. The chamfered section 121 brings a side wall of a projection 131 into pressure-contact with it when the projection 131 is calked. Consequently, the side wall of the projection 131 comes into pressure-contact with the chamfered section 121 in larger area, and it is possible to prevent conventional pressure-contact of a corner of the spiral bimetallic strip 12 and galling of the side wall of the projection 131 and ensure press-fitting and tightening further. As a result, even if there is a difference in thermal inflation between a coupling main body and the spiral bimetallic strip 12 when temperature of the coupling main body rises, it is possible to ensure pull-out strength of the spiral bimetallic strip 12 sufficiently and prevent concentration of local stress due to positional deviation and eccentric load of the spiral bimetallic strip 12. |
