| 摘要 |
PROBLEM TO BE SOLVED: To provide a cutting tool having a cutting-edge with an excellent compressive strength. SOLUTION: In the excavating tool having a structure, in which a plurality of posts made of a tungsten carbide-based cemented carbide are fixed onto the front end face of a bit body made of an alloy steel in a specified array and the cutting-edge pieces made of sintered diamond are blazed directly onto the front side faces of the above-mentioned posts, the cutting-edge piece has a composition formed of diamond coarse grains having grain size of 10-50 μm and a mean grain size of 20-30 μm, 80-90 vol.% diamond fine grains having a grain size of 7 μm or less and a mean grain size of 2-4 μm, a sintered assistant component composed of one kind or more of the carbonates and oxides of Mg, Ca, Sr and Ba and inevitable impurities as the remainder. The excavating tool is constituted of the sintered diamond having a texture, in which the diamond coarse grains are mutually bonded adjacently, there is the sintered assistant component among the diamond coarse grains and the diamond fine grains are dispersed and distributed in the sintered assistant component. |
