Abstract

Large extrusion container (EC) is the key part of an extrusion machine, and generally it depends on shrink fitting of multi-layers to boost its strength. Because of the harsh condition of high temperature and pressure, the shrinkage between every 2 layers of EC would be consumed due to creep deformation. However, shrinkage loss would generate insufficient support to each outer layer and result in axial endplay or crack of EC, which brings both safety issues and economic losses. Since the repair and replacement of EC due to its failure are significantly time-consuming as well as expensive, assessment of EC’s lifetime related with shrinkage loss resulting from creep deformation is of great meaning and importance. However, research of this field is very limited. In this paper, based on the proposed damage-coupled constitutive model incorporating creep behavior, the relationship between shrinkage and creep deformation and the influence of shrinkage loss on EC’s serving lifetime have been investigated. Furthermore, shrinkage loss under different contact presses and extrusion speeds has been discussed. Results can be used to guide the shrinkage design of EC’s shrink-fitting in design stage and modify the manufacturing dimension of replacement layer after certain failure occurrence, thus prolong the serving lifetime of EC to the utmost.

摘要

大型挤压容器（EC）是挤压机的关键部件，一般依靠多层热缩配合来提高其强度。由于高温高压的恶劣条件，每2层EC之间的收缩会因蠕变变形而被消耗。然而，收缩损失会产生对每个外层的支撑不足，并导致EC的轴向端隙或裂纹，从而带来安全问题和经济损失。由于 EC 失效后的修复和更换非常耗时且昂贵，因此评估与蠕变变形引起的收缩损失相关的 EC 寿命具有重要意义和重要性。然而，该领域的研究非常有限。在本文中，基于所提出的结合蠕变行为的损伤耦合本构模型，研究了收缩和蠕变变形之间的关系以及收缩损失对EC使用寿命的影响。此外，讨论了不同接触压力和挤压速度下的收缩损失。结果可在设计阶段指导EC热缩配件的热缩设计，并在出现一定故障后修改替换层的制造尺寸，从而最大限度地延长EC的使用寿命。