| 摘要 |
PROBLEM TO BE SOLVED: To improve durability by providing a cutter bit with a main cemented carbide-made tip and an auxiliary cemented carbide-made tip, making the toughness of the auxiliary cemented carbide-made tip higher than that of the main cemented carbide-made tip. SOLUTION: With regard to a cutter bit in which a main cemented carbide- made tip 31a and an auxiliary cemented carbide-made tip 35 are arranged, the main cemented carbide-made tip 31a is protected by the right and left auxiliary cemented carbide-made tip 35 in the direction of its cutting. At the time of cutting, the main cemented carbide-made tip 31a and the auxiliary cemented carbide-made tip 35 substantially simultaneously cut a cutting face or the auxiliary cemented carbide-made tip 35 cuts the cutting face in advance. Therefor even if a high hardness gravel exists, the auxiliary cemented carbide-made tip 35 of high toughness always cuts the cutting face in advance of the main cemented carbide-made tip 35a or they simultaneously cut it. The auxiliary tip of higher toughness than the normal receives impact face by the gravel and the like, and the impact force the main chip receives is relieved to prevent damage of the tip. |
