| 摘要 |
PROBLEM TO BE SOLVED: To easily insert a standard nut into an arbitrary intermediate position of a dovetail groove by forming a dovetail groove structure by a nut insertion opening part, a nut seating part, and a nut insertion auxiliary part recessed on a side wall of the nut seating part. SOLUTION: A dovetail groove structure comprises a nut insertion opening part 11 having a groove width W1 narrower than a nut width across flat WN, a nut seating part 12 having a groove width W2 corresponding to the width across flat WN, and a nut insertion auxiliary part 13 having a groove width W3 and recessed on one side wall of this seating part 12, and has the approximately L-shaped cross section. When a standard hexagon nut N is inserted from an oblique upper part of the opening part 11 at an intermediate position of the dovetail groove, a shaft center of the nut N is rotated in a state that a round machining part of the nut N is slided on a bottom of the dovetail groove and an end surface of the opening part 11. Then the nut N is temporarily escaped into the auxiliary part 13, whereby the rotation of the nut N in the dovetail groove can be assisted. When this rotation is completed, one side wall of the nut N is retracted to the seating part 12 to achieve the fastening work standby state.
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