| 摘要 |
PROBLEM TO BE SOLVED: To provide a nut with a washer and a bolt with a washer applicable to either tool of a center engagement type or a peripheral engagement type, in which a neck part as a connection part of a washer part to a nut part or a bolt part are free from defects, with seat boring smoothly conducted, and with loosening due to abrasion of wood less likely to occur. SOLUTION: The nut part 3 (or the bolt part) is integrally provided with the washer part 2 at a center lower part, a plurality of lock holes 6 for a first rotation tool are provided at a center part in an upper surface, and lock holes 8 for a second rotation tool in a peripheral part of the upper surface. In the neck part, a lower surface of the washer part 2 toward an upper part of an outer surface of the nut part 3 is formed as a curved surface 5 curved in a recess toward the center, so that thickness of the neck part is secured. A plurality of cutting blades 7 are formed in the curved surface 5. The lock holes 8 for the second rotation tool are formed as slits to leave opening even when claws of the rotation tool are engaged. COPYRIGHT: (C)2005,JPO&NCIPI
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