| 摘要 |
PROBLEM TO BE SOLVED: To eliminate wasteful use of a lead by extremely shortening the remainder of the lead. SOLUTION: A retaining chuck 8b is fixed to almost the forward end of an inner hole part of a slider 8 inserted into the inner hole of a nose part 3 in such a state that the tip part projects from the forward end of the nose part 3. Further, the peripheral face of the inner hole of the nose part 3 is engaged with the outer peripheral face of the slider 8 so that the slider 8 is prevented from moving forward between both peripheral faces at the retraction position of the slider 8. In addition, at the retraction position of the chuck 8b, the engagement part provided at the rear end of the slider 8 and an engagement part at the forward end of the chuck 7 are engaged together and in this state, until the chuck 7 advances and a clamping member 10 comes into contact with the stepped part of the nose part 3, the engagement is removed. After that, with the further advance of the chuck 7, the engagement of the slider 8 is removed and consequently, the slider 8 also makes headway. Then when the chuck 7 proceeds to the farthest extent, from which the chuck 7 moves backward, the engagement part provided at the rear end of the slider 8 and the engagement at the forward end of the chuck 7 are engaged together and the slider 8 is movable backward through an interlocking action between the chuck 7 and the slider 8.
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