| 摘要 |
PROBLEM TO BE SOLVED: To provide a screw head with excellent convenience for enabling a fastening operation to various screw parts with different dimensions by a common fastening tool, and for enabling a fastening operation by a fastening tool individually used according to each dimension, and a fastening tool usable to various screw parts of different dimensions having such screw heads. SOLUTION: This screw head 110 comprises first side faces 111a, 111b, 111c, 111d set to a double face width according to a JIS standard, and second side faces 112a, 112b set to a constant double face width regardless of size of the screw parts. Because screw parts can be fitted to the second side faces 112a, 112b regardless of the size by using a special-purpose tool having a fit opposed face of a constant width, a fastening operation of the screw parts with a plural kinds of sizes is possible by only one tool. COPYRIGHT: (C)2004,JPO
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