| 摘要 |
<p>A metal rod having a conical or pyramidal cut extremity is used to make a mandrel (21) of a blind rivet. The rod is held in place between a pair of die segments (11) such that an end of a preset length including the cut extremity is swageable and protrudes from an upper surface (14) of the segments (11). Subsequently, the swageable end (26) is axially compressed to form a mandrel head (27) by a punch (12) which has a lower face (17) extending parallel to the upper surface (14) of the segments (11) and a conical or pyramidal recess (18) fittable on the cut extremity. Thus, a free intermediate portion of the swageable end (26) compressed by the punch (12) swells radially to form the head (27) which has a flat flange (31) from which the cut extremity (20a) protrudes as a lug (32) upwardly and centrally. The mandrel (21), which has the head formed uniform without any eccentricity about the axis of a mandrel body, can thus be produced inexpensively using nail manufacturing apparatus. <IMAGE></p> |
