FORMING METHOD FOR TAPER PIPE BY UUO FORMING

摘要

PURPOSE:To make possible the edge parts of the pipe blank to be roughly formed into circular arc, without necessity of the exclusive edge forming press, by inserting a specially shaped mandrel, at carrying out the O-forming press after forming the trapezoid cut plate into U-type. CONSTITUTION:The material plate P, cut into a trapezoid shape whose logitudinal length is equal to length of the taper pipe like as the pole to be manufactured, and the breadth of both ends are respectively equal to circumferential lengths of small diameter end and large diameter end of the taper pipe, is bent into U-type. This U-type material is set between the press dies 1, 2, in which the truncated cone type halved cavities of the O-forming press are arranged facing each other from upside and downside, on purpose to form this material into the ellipse type. The mandrel 3 is inserted into this U-type material P; this mandrel 3 has two longitudinal flat planes on both sides obtained by cutting above truncated cone, and also has a part of conical plane on upside and downside. Then by pressing the dies 1, 2, the straight zone of both edges of the material P is bent inward, and is formed into almost perfect curvature. After that, the dies 1, 2, are released from the press, the mandrel 3 is moved to the side of large diameter, and then, the material P is again pressed by the dies 1, 2, finishing the formation.