CUTTER BIT OF TUNNEL EXCAVATOR

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PROBLEM TO BE SOLVED : To provide a cutter bit for a tunnel excavator which can prevent the accumulation of excavated earth and sand at the bottom of a thread at the back of the double-head type cutter bit by a simple structure and can increase its life. SOLUTION : The cutter bit 5 for the tunnel excavator has a shank 8, a pair of cemented carbide tips 6, 7, and a back 9. The shank 8 is attached to a cutter head 4 which is driven in the normal direction or in the reverse direction around an axis in the longitudinal direction of a tunnel. The pair of cemented carbide tips 6, 7 are provided in the rotation circumferential direction of the cutter head 4 at spaces, and the back 9 is formed in a valley shape at the working face side of the shank 8 between the cemented carbide tips so that the center of the cutter head 4 in the rotation circumferential direction A can be recessed. An earth-and-sand flowing part 10 which is shaped like a mountain is formed at the bottom 9c of the thread at the back of the shank 8 in order to discharge the excavated earth and sand which flow from the cemented carbide tips 6, 7 to the bottom 9c of the thread along the rotation circumferential direction A of the cutter head 4, to the inside and the outside of the cutter head 4 in the rotation radial direction B. COPYRIGHT : (C)2010, JPO&INPIT