| 摘要 |
PROBLEM TO BE SOLVED: To prevent a fastening fixture from being loosened when vibration is applied to a building lumber, and when it is shrunk due to drying. SOLUTION: A washer 7 formed out of a tabular spring steel roughly into a truncated cone shape, is interposed between a fastened member such as lumber and a nut 6. When the nut 6 is fastened, the spring steel washer 7 is crushed while being shrunk in the axial direction, and the inner wall 9a of the side surface 9 of the washer is brought into contact with the surface of a plane washer 5. Since the inner wall 9a is depressed to the bottom surface side of the washer while being curved, when the washer is fastened, its contacting surface area with the plane washer 5 is larger as compared with that of a case of a linear flat surface, and its fastening force becomes thereby greater so as to be hardly loosened.
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