Taper Drawing of Non-Circular Steel Tubes by Dieless Eorming

在现有的工艺技术条件下，用工模具对非圆钢管进行纵向锥形拉拔变形是不可能的。本课题将辊弯成形技术与无模成形技术相结合，开发了一种制造各种截面形状锥形管的新方法，并在基础研究工作中取得了以下成果，同时讨论了工业应用中的一些问题：（1）利用感应加热装置（最大）的实验装置;在5吨Instron试验机上，采用不同的加热、冷却和变形条件，对21 × 21 mm，壁厚1.2 - 2.1 mm的方钢管进行了拉拔试验，得到了锥度角误差在0.1%以内的锥形管<plus-minus>。(3)对加热能力为60千瓦、牵引装置为50吨的无模拉伸机进行了初步设计，证实了这一新工艺工业应用的可能性。

It is impossible to give tapered drawing deformation in longitudinal direction for non-circular steel tubes using tools and dies, at the present technological knowledge and know-how. In this project, a new method for making tapered tubes having various cross-sectional shapes has been developed, combined with the techniques of roll forming and dieless forming.The following results are obtained from the fundamental research work and some problems for industrial avplication are also discussed :(1) Using the experimental sets of an induction heating device (max. power of 3 Kw, frequency of 2 MHz) and an Instron testing machine of 5 tons, square shaped steel tubes (21 x 21 mm, wall thickness 1.2 - 2.1 mm) were drawn for obtaining tapered tubes under various heating, cooling and/or deformation conditions ; a precise drwing can be conducted within the error of <plus-minus> 0.1 % in a taper angl(2) Suitable conditions of dieless drawing were investigated experimentally and theoretically.(3) A basical design of a proto type dieless drawing machine having a heating ability of 60 Kw and a pulling device of 50 tonf has been conducted, and the possibility of industrial application of this new process was confirmed.