To avoid a problem of over-threading of an axis member having shaped sections with two kinds of different, large and small, diameters.
In a cross section of a section 32 with a large diameter, the area ratio of a projection 32b other than a groove to a groove 32a is formed to be as large as possible, particularly, to shape a projection 32b into a trapezoid in a cross section, without compromising the function and workability of the section 32 and the strength of the threading die for positioning and flexible deformation guiding, which results in sufficiently providing the margin for flexible deformation of the section 32 for simultaneously threading a section 30 with a small diameter and the section 32. Consequently, the axis-to-axis distance of threading dies where the section 32 enters an over-threading region becomes shorter to provide a region corresponding to the axis-to-axis distance of the threading dies required for threading the section 30, which allows a simultaneous threading of the section 30 and the section 32.
Miyazaki Yoshio
Kaoru Onozuka
Akio Tagami
High Masahiro
Tsutomu Kato
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