A Research Of Region Segmentation Approach And Regional Life Unification For Hot Forging Dies

The lifespan study for hot forging dies is a hot issue in forging industry. Accordingto statistics, the costs for tooling, which involve purchase, repair and replacement, areup to40%of the value of the final product and prolongation among prevention ofunexpected failure result in a reduction around30%in the production costs. The servicelife of tools has a high impact on the competitiveness of closed-die forging shops. Toincrease it, metallurgical modification of the die surface, coating and geometric changesof the engraving have already been studied in different works. But there aren’t manystudies about how to get a suited service life. Compared with long life tools, scheduledlife tools are more efficient and economical, especially for large-scale tools.In this study, a rigid-plastic finite element simulation was used to simulate the finishforging process of a crankshaft named QP-123based on the commercial code DEFORM3D/2D. Combined with the simulation results e.g. temperature distribution, stressdistribution, tool wear and ideas of equal life design, a new tool design method wasproposed for a new type of economical forging tool. This method is aim to get a unifiedregional life in different tool regions and mainly include three procedures. At first, thedistribution and evolvement of temperature, stress and tool wear in a multiple forgingprocess have been analyzed; also, the data of failure position and pattern in practicalmanufacturing process has been collected. Then, a region segmentation approach basedon region feature was presented in forms of formula and rules. In this approach, a finishforging tool of the selected crankshaft was divided into five regions i.e. multi-failureregion, wear region, plastic deformation region, crack region and matrix region. Everyregion has its classification standard and the main failure. At last, the final procedurewas material selection for different region. It is the most important part in the proposedmethod, a series of rules for material selection were made to define a suitable materialfor a featured region. There are general material rules: good enough to avoid failures;have a suitable lifespan and feasible to link with other region. Based on the methodhave presented above, a net-equallife forging tool is manufactured and anexperimentalindustrial production was conducted. The results show that the tool designed underguidance of the new method is more efficient and economical than classical tools.This paper introduced the idea of equal life into mould design, try to get a new typeof forging tools which can custom-made according to the working environment and service life. We need a suitable life tool rather than a long life tool in many cases andtool life customization will be more appropriate for new manufacturing industry.