| 摘要 |
PROBLEM TO BE SOLVED: To reduce the weight of steel material of a threaded steel bar for use in a PC bar and a reinforcing bar by rationally reducing the mass of a node part of the threaded steel bar by improving the shape of the node. SOLUTION: The shape of the thread is set as: (1) the value of the root width ratio (= the width of the root of a thread / the width of the thread ridge) is set to be 1.4-3 while the value is set to be 1.0-1.3 in conventional products; and (2) the shape of the longitudinal section of a thread is altered to a triangular shape having the roundness in the top part from the trapezoidal shape of the conventional products. The mass ratios in the node parts are each reduced by half from 5-12% in the conventional products. The same effects by the same method is expected about a three-line thread with three-way rolls and a four-line thread with four-way rolls similarly to the two-line thread with two-way rolls. COPYRIGHT: (C)2009,JPO&INPIT
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