1、外文资料翻译 Overview of adaptable die design for extrusions W.A. Gordon.C.J. Van Tyne.Y.H. Moon ABSTRACT The term adaptable die design is used for the methodology in which the tooling shape is determined or modified to produce some optimal property in either product or process. The adaptable die design m
2、ethod, used in conjunction with an upper bound model, allows the rapid evaluation of a large number of die shapes and the discovery of the one that produces the desired outcome. In order for the adaptable di e design method to be successful, it is necessary to have a realistic velocity field for the
3、 deformation process through extrusion dies of any shape and the velocity field must allow flexibility in material movement to achieve the required material flow description. A variety of criteria can be used in the adaptable die design method. For example, dies which produce minimal distortion in t
4、he product. A double optimization process is used to determine the values for the flexible variables in the velocity fie ld and secondly to determine the die shape that best meets the given criteria. The method has been extended to the design of dies for non-axisymmetric product shapes. 2006 Elsevie
5、r B.V. All rights reserved. Keywords: Extrusion； Die design； Upper bound approach； Minimum distortion criterion 1. Introduction New metal alloys and composites are being developed to meet demanding applications. Many of these new materials as well as traditional materials have li mited workability.
6、Extrusion is a metalworking process that can be used to deform these diffi cult materials into the shapes ne eded for specific applications. For a successful extrusion process, metalworking engineers and designers need to know how the extrusion die shape can affect the final product. The present wor
7、k focuses on the design of appropriate extru sion die shapes. A methodology is presented to determine die shapes that meet specific criteria: either shapes which pro -duce product with optimal set of specified properties, such as minimum distortion in the extrudate, or shapes which produce product b
8、y an optimized pro cess, such as minimum extrusion pressure. The term adaptable die design is used for the method nology in which the die shape is determined or modified to produce some optimal proper ty in either product or process. This adaptable die design method, used in conjunction with anupper
9、 bound model, allows the r apid evaluation of a large num ber of die shapes and the discove ry of the one that can optimize the desired outcome. There are several conditions that need to be met for the adaptable die design method to be viable. First, a generalized but realistic velocity field is n e
10、eded for use in an upper bound model to mathematically describe the flow of the material during extrusion through dies of any shape. Second, a robust crite - rion needs to be established for the optimiz ation of the die shape. The criterion must be useable within an upper bound model. The full detai
11、ls of the method are presented elsewhere 16. In the present paper, following a review of previous models for extrusion, the flexible velocity field for the d eformation region in a direct extrusion will be briefly pr esented. This velocity field is able to characterize the flow through a die of almo
12、st any configuration. The adaptable equation, which describes the die shape, is also presented. The constants in this die shape equation are optimized with respect to a criterion. The criterion, which can be used to minimize distortion, i s presented. Finally, the shape of an adaptable die, which pr
13、oduces of an extruded product with minimal distortion, is presented. T he objective of the present paper is to provide a brief overview of the adaptable die design method. 2. Background 2.1. Axisymmetric extrusion Numerous studies have analyz ed the axisymmetric extrusion of a cylindrical product fr
14、om a cylindrical billet. Avitzur710 proposed upper bound models for axisymmetric extru sion through conical dies. Zimerman and Avitzur 11 modeled extrusion using the upper bound method, but with generalized shear boundaries. Finite element methods were used by Chen et al. 12 and Liu and Chung 13 to
15、model axisymmetric extru sion through conical dies. Chen and Ling 14 and Nagpal 15 analyzed other die shapes. They developed velocity fields for axisymmetric extrusion through arbitrarily shaped dies. Richmond16 was the first to propose the concept of a streamlined die shape as a die profile optimiz
16、ed for minimal distortion. Yang et al. 17 as well as Yang and Han 18 developed upper bound models for streamlined dies. Srinivasan et al.19 proposed a controlled strain rate die as a streamlined shape, which improved the extrusion process for materials with limited workability. Lu and Lo 20 proposed a die shape with an improved strain rate control. 2.2. Distortion and die shape analysis Numerous analytical and experimental axisymmetric extru sion
