流线形型材挤压模设计的一种新方法

流线形型材挤压模能方便地挤出高质量的铝合金型材,尤其适合于挤出钛、钢等各类高强度合金型材,在航空宇航工业中有着广阔的应用前景,为此,本文提出了一种采用势流模型、兼有理论上的严密性和计算方法上的简单实用性的任意截面型材流线形挤压模的新的设计方法,并编制出相应的软件,与已经开发成功的型材截面自动识别软件及通用的曲面加工后置处理软件结合在一起构成一完整的流线形型材挤压模CAD/CAM系统。

A New Method of Designing Streamlined Dies for Shape Extrusion

Producing the extruded sections of high strength alloys from round billets through streamlined dies is an attractive technique. In designing the die contour, only a few systematic analyses have been reported. The method developed by Nagpal, Altan and Gunesakera [8,9] is essentially an engineering algorithm and is applicable only to the sections with symmetric axes. Yang and Lee [5,6,7,14] formulated an analytical expression for the die contour by utilizing external conformal mapping of sections, but it seems practically very difficult to find a mapping function when the section to be extruded is complicated in shape. In this paper, a new method is proposed for designing contour of streamlined extrusion die using boundary element method on the assumption that the extrusion metal flow is a potential one. The method is versatile in practice and time-saving in computation. The die contour for section of arbitrary shape can be designed automatically using this method. The theoretical predictions are in good agreement with experimental results. Using this method, a CAD/CAM system for the streamlined extrusion dies has been built and its flow chart is described.