| 摘要 |
PURPOSE:To impart high hardness and high-grade feeling to the whole of a case, by constituting a back of two bodies consisting of a main body composed of ceramics or an artificial jewel and a core composed of a metal and bonding the main body of the back and the core by soldering. CONSTITUTION:A groove 1a is formed to the inner wall of a middle 1 composed of ceramics or an artificial jewel and the engaging projection 3a of a core 3 composed of a metal is arranged at the position opposed to the groove 1a. The metal core 3 and a back main body 2 composed of ceramics or an artificial jewel are bonded by soldering the core abutment surface 2a and soldering bonding surface 3b opposed to each other of both of the core 2 and the back main body 3 and function as a back. The metal core 3 is bent by its elasticity to be smoothly incorporated in the middle 1 and the back 2 is fixed to the middle 1 by engaging the engaging projection 3a with the groove 1a formed to the inner wall of the middle 1. Herein, the back main body 2 and the core 3 are bonded by soldering and metallizing processing is applied to the back main body 2 composed of the ceramics or artificial jewel. by this method, excellent corrosion resistance and airtightness are obtained.
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