| 摘要 |
PROBLEM TO BE SOLVED: To provide a screw joint structure of an excavation tool that enables an unskilled operator to easily recognize the use limit of a screw of the screw joint structure and securely prevents the tool from being broken, and the excavation tool using the same.SOLUTION: There is provided a screw joint structure 1 of an excavation tool that connects a drilling bit and a drilling rod, drilling bits 2, 3, or a drilling rod and a coupling to each other, and is constituted by threadably engaging a male screw 5 having a male screw part 6 formed thereon and a female screw 21 having a female screw part 2 formed thereon with each other. The female screw 21 has a peripheral wall part 23 having the female screw part 22 formed at an inner periphery, and the peripheral wall part 23 is provided with a first index part 31. The male screw 5 is provided with a second index part 32 arranged at a different peripheral position from the first index part 31 in a state in which the male screw 5 and female screw 21 engage each other, and when the male screw 5 and female screw 21 rotate relatively in a peripheral direction due to the abrasion of screws, the positions of the first index part 31 and second index part 32 along the peripheral direction overlap each other. |
