| 摘要 |
PROBLEM TO BE SOLVED: To provide a rifle tube drawing tool capable of preventing occurrence of seizure during a drawing and being easily and inexpensively be manufactured. SOLUTION: In the rifle tube drawing tool 1, a plurality of spiral grooves 1a are formed on its outer circumferential surface. The first line L1 passing through a top except a tip of the tool of one groove ridge 1b across the axis of the tool in side view is inclined inwardly from a tip side of the tool toward a rear end side. The angleθ1 formed by the first line with respect to the axial direction of the tool in plan view is set to be larger than the angleθ2 formed by the second line L2 passing through a bottom part except the tip of the tool of one spiral groove across the axis of the tool in side view. An edge of one groove ridge is chamfered in an outwardly projecting curve, and its radius r of curvature is set to be a constant value from the tip of the tool to its rear end. COPYRIGHT: (C)2007,JPO&INPIT
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