提高挤压筒内壁耐磨性的WC-12Co涂层有限元优化

Finite Element Optimization of WC-12Co Coatings Aiming to Improve Wear Resistance of the Extrusion Container Inner Wall

目的获得WC-12Co涂层厚度的优化方案,以提高挤压筒内壁的耐磨性。方法基于ANSYS软件,以两层套圆挤压筒为研究对象,进行挤压筒内壁有无WC-12Co涂层及涂层厚度对挤压筒应力分布影响的有限元模拟。结果施加涂层后,在装配、挤压-装配和热-挤压-装配情况下,涂层的应力分布合理且都小于该温度下涂层的屈服强度;而在热-装配条件下,由于热应力和过盈量引起的预应力相互抵消,使得总体应力较小;同时,等效应力在涂层与挤压筒的结合处发生剧烈变化,而在其他位置的应力相较于不施加涂层时变化较小。在各种工况下,挤压筒内出现的最大等效应力均随着涂层厚度的增加而降低,且热-挤压-装配下涂层厚度对最大应力影响最大。结论在所选涂层厚度范围内,涂层厚度越大,挤压筒所受的最大应力越小,越有利于挤压筒使用。当涂层厚度为6.4 mm时,各种工况下的最大等效应力最小,此时在热-挤压-装配工况下的最大等效应力为760.61 MPa,已经远低于H13钢的屈服强度,可以满足实际使用要求。

The work aims to improve wear resistance of extrusion container inner wall by acquiring optimization scheme of WC-12 Co coating thickness. With two layers of multi-shrinking extrusion containers as research objects, finite element modeling was performed to study effects extrusion container inner wall with WC-12 co coatings or not and coating thickness on stress distribution of extrusion containers based on ANSYS software. After the coatings were applied, coating stress was distributed reasonably and below yield strength of the coatings at the temperature under the conditions of assembly, extrusion-assembly and heat-extrusion-assembly; overall stress was lower because prestress arising from thermal stress and magnitude of interference cancelled each other out under the condition of heat-assembly; meanwhile, equivalent stress changed significantly at the joint between the coatings and extrusion containers, while stress in other positions changes slightly compared to that when no coating was applied. Under various conditions, the maximum equivalent stress in the containers decreased with the increase of coating thickness, and coating thickness had greatest effect on the maximum stress under the condition of heat-extrusion-assembly. As the coating thickness increases in the selected range of coating thickness, the maximum stress carried by the extrusion containers decreases, which is more conductive to the use of extrusion container. When the coating thickness is 6.4 mm, the maximum equivalent stress under all working conditions is the minimum, and that under the condition of heat-extrusion-assembly is 845.38 MPa, which is far lower than yield strength of H13 steel, hence it meets actual usage requirements.