Thermo-mechanical Load In The Near-surface Layer Of Hot Forging Die Impression

Forging takes a pivotal position in equipment manufacturing industry. Hot forging dies continuous work in high temperature and high pressure environment during forging process, near-surface of mold impression is affected by periodic thermal load and mechanical load, which can lead to short service life of hot forging die. In recent years, the researchers pay more attention on the forging process than load situation that the mold bared. Therefore, load in the near surface layer of mold impression was studied based on numerical simulation results of forging process, the researches were as followed:1,Physical field analysis of surface and near-surface layers of hot forging die's impression. heat-affected zone is only 2 to 3 mm below the impression was known by analyzing different forging speeds, temperature and thermal stress fields, mechanical stress, stress distribution and changes in law of hot forging dies after forging process. And as the forging speed decreased, the thermal stress rose in impression surface, thermal stress influence area expanded in near surface impression layer; the mechanical stress that the mold bared reduced, the overall mechanical stress field appeared gradient distribution. Mold integrated stress was the composition of thermal stress and mechanical stress in their own direction.2,The load effect from different forging equipment applied on hot forging die. Three typical forging equipments were picked by different loading pattern:the impact hammer-forging equipment; static hydraulic press forging equipment; and forging equipments between them. The load effects from those three typical equipments were: when the hammer-forging equipment worked, the contact time between die and workpiece was very short, the load that the die bared was mainly depended on mechanical load; when the hydraulic press forging equipment worked, the workpiece deformation is long, the load that the die bared mainly depended on thermal load; when the forging press machine worked, the mechanical load is still dominant in the view of the load that the die dared.3,Researches on FGM multilayer metal hot forging die. Built multilayer metal hot forging die finite element mold. And finite element analysis were done, the temperature field indicated:compared with homogeneous hot forging die, multilayer metal can reduce the temperature peak of die impression; stress field indicate: compared with homogeneous hot forging die, multilayer metal hot forging die can reduce the equivalent stress of dies during forging production, thereby, prolong the forging die's service life. Layer stress field analysis of multilayer metal hot forging die shows:composite layer's design of FGM structure hot forging dies is critical, if the material properties continuous changed, material multilayer metal die's service value would fully used, or else, it would lead to multilayer hot forging die premature failure because of layer separated.4,Hot forging die service life prediction after process optimization. Finite element wear analysis and die wear service life forecast of homogeneous hot forging dies and long-life hot forging die were made, the result indicated:multilayer metal hot forging die can largely prolong the service life of dies about 5 times. Provide new method to multilayer metal forging die service life prediction.This paper prime analyzed the load that hot forging die bared during working, load mechanism of forging dies were analyzed; then the mainly failure mold that the load affected through different loading of forging equipment was judged; at last, changed die's structure and performance through the development of new die, to prolong the service life of hot forging dies.