Defining a method of evaluating die life performance by using finite element models (FEM) and a practical open die hot forging method

摘要

Die wear, which is defined as a surface damage or removal of material from one or both of two solid surfaces in a sliding, rolling or impact motion relative to one another, is considered the main cause of tool failure. Wear is responsible for 70% of tool failure and a potential source of high costs; as much as 30% per forging unit in the forging industries [1]. This paper presents a unique wear prediction and measurement method for open die forging using a modified Archard equation, 3D FE simulation (to represent the actual forging process precisely) and an industrial scale forging trial. The proposed tool and experimental design is aimed at facilitating a cost effective method of tool wear analysis and to establish a repeatable method of measurement .It creates a platform to test different type of lubricants and coatings on industrial scale environment. The forging trial was carried out using 2100T Schuler Screw press. A full factorial experiment design was used on 3D simulation to identify the process setting for creating a measurable amount of tool wear. Wear prediction of 28.5 μm based on the simulation correlated with both Infinite Focus Optical Microscope and Coordinate Measuring Machine (CMM) measurement results of the practical trial. Thermal camera reading showed temperature raise on the area with maximum wear, which suggests that increase in contact time, causes thermal softening on tool steel. The measurement showed that abrasive wear and adhesive wear are dominant failure modes on the tool under these process conditions.