| 摘要 |
PROBLEM TO BE SOLVED: To prevent the thermal deterioration of a diamond layer by laser- welding the holder sections of composite tips and the blade bases of a steel rotor to each other via an additive metal mainly made of cobalt. SOLUTION: The back faces and lower faces of composite tips 5 (holders 6) are brought into contact with the back faces 4a and support faces 4b of the mount faces 4 of the blade bases 3 of a steel rotor 2 via an additive metal, and these contact sections are laser-welded over the whole length to obtain a rotary saw 1 fixed with the cemented carbide composite tips 5 on the outer periphery of the rotor 2. The mating faces with the blade bases 3 are made of a cemented carbide alloy containing a cobalt component 9-20%. When a cemented carbide alloy containing a cobalt component 8% or below is used for the additive metal, cracks are easily generated at a cemented carbide section by welding heat at the time of laser welding. When a cemented carbide alloy containing a cobalt component 21% or above is used for the holders 6, the sticking strength of diamond layers 7 is lowered.
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