| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method for a rice ball-shaped triangular thread, capable of reducing manufacturing costs of a mold, capable of manufacturing a triangular thread at low cost, capable of manufacturing a long triangular thread, having low abrasion of the mold, and capable of making a rice ball-shaped sectional triangular bar part from just below a head part. SOLUTION: A continuously drawn triangular wire material 21 having a rice ball-shaped section is prepared. A part projecting from the end surface 27 of a mold part 23 of the triangular wire material 21 is formed into a head part 32 in a state where the triangular wire material 21 is partially inserted and held in a circular hole 26 of the mold part 23. A screw thread is formed on a rice ball-shaped sectional triangular bar part 36 extending from just below the head part 32 by rolling.
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