| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method for a loosening preventing bolt capable of manufacturing the loosening preventing bolt provided as a double- thread at the shank of the same bolt by one rolling operation. SOLUTION: The manufacturing method for the loosening preventing bolt is characterized in that a coarse screw thread 4 for a tightening nut and a fine screw thread 5 for a lock nut are provided at the same outside diameter in the shank 1a of the bolt 1, and a projection 8 for forming the fine screw thread 5 only for the portion wherein the fine screw thread 5 overlaps the coarse screw thread 4 is provided in a first half 6a of a flat die and a coarse screw thread die 7 is provided in a second half 6b of the flat die for rolling 6. Double-threads 4, 5 are formed on the shank 1a by one rolling operation, by using the flat die 6. COPYRIGHT: (C)2004,JPO
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