Study And Application Of Friction And Wear Behavior Of Commonly Used Die Materials

As an important production equipment and the direction of process development,the die which is called “golden key”,“the mother of manufacturing” and so on, plays anincreasingly significant role in the scale production of modern industry. But in ourcountry, at present the research on friction and wear properties of die materials is notvery deep, especially the research on wear mechanisms and the transformation of themis still not mature, leading to the less accurate prediction of die wear. Compared with theinternational advanced level, the average life of hot-forging die in our country is3000-5000and has a big gap. It causes great economic losses and serious waste ofhuman resources. Die wear is the determining factor of die life and it accounts for morethan70%of the total die failure. Therefore, it is very significant to study on how toreduce die wear and improve the life of hot-forging die.In this paper, the friction and wear properties of two representative die materialwas studied by wear test. It can gain a better understanding of the main factors of wearand some measures were proposed to reduce friction and wear. Then, the typical wearcharacteristics of worn surface and wear debris were observed by SEM and a new wearcalculation model was proposed to calculate the die wear more accurately. Afterwards,taking the mandrel die of wheel hub forging process as example, based on the new wearcalculation model, FEA, wear test, BP neural network and SQP algorithm, an optimaldesign of the mandrel geometry was carried out to make the wear of die less and moreuniform. Finally, experiments were performed on HSR-2M wear-testing machine toverify the accuracy of the proposed wear calculation model and the validity of theoptimal design of mandrel geometry.Research results show that, severe wear of the H13steel appears at high speed andhigh load condition, but the severe wear of the welding die steel happens at low speedand high load. Therefore, the die geometry can be optimized in practical production tochange the contact condition of the die and improve the wear condition of the areawhere is severe wear. The main wear mechanisms of common die material are adhesivewear mechanism, abrasive wear mechanism and oxidation wear mechanism. The weardepth calculated by new wear calculation model shows a good agreement with the weardepth measured by wear test. Compared with the initial mandrel geometry, the uniformwear and the maximum wear of the optimized mandrel geometry are decreased by 38.9%and12.5%, respectively. Therefore, the proposed wear calculation model isaccurate and the optimization of the mandrel geometry is effective. This study will bebeneficial to the accurate prediction of die wear and the optimal design of die geometryin hot-forging process.