| 摘要 |
PURPOSE:To use a sintered hard metal, and also, to improve the durability with high accuracy by constituting a V-groove having width and depth corresponding to thickness of a needle material on a joint of two pieces of square poles. CONSTITUTION:First of all, two pieces of square poles 4, 5 of a sintered hard alloy, etc., are prepared, and the respective prescribed corner faces are chamfered by grinding them with a prescribed inclination by using a grindstone and inclined surfaces (a), (b) having prescribed length and width and its variation are formed, respectively. Subsequently, two pieces of square poles (a), (b) on which the inclined surfaces (a), (b) are formed are arranged in parallel so that the inclined surfaces (a), (b) are adjacent to each other, and fixed by a jig, etc., by which a forging pressure forming die having a V-groove 6 of the inclined surfaces (a), (b) can be manufactured. As for these inclined surfaces (a), (b), clearance part chamfering of wide width is constituted on an initial end, respectively, and also, in accordance with a shape of different thickness of a triangular part of a needle material, the tip part is formed to narrow width. Accordingly, in the initial end of the V-groove 6, a clearance part groove 6' which is deeper than this end and wider than its width is formed continuously. |
