Basic Research In Best Coupling State Between Material And Working Properties Of Forging Dies

Forging die is important basic technics equipment in manufacturing. When it is used to forge workpieces, it endures pulsing heat and machine load. Surface of die occurs four damnification such as thermal fatigue, phase change, temper and plastic distortion under heat load. Surface of die occurs four damnification such as brittleness break, machine crack, machine wear and plastic distortion under machine load. All damnification influences severely life of die.Manufacture and practice show that how to improve life of die is a complex problem. Its research content comes down to coupling of material and working properties. In order to investigate the coupling problem, forging die is as research object in the thesis.These are four parts in research content. In the first part, it is concluded that load is the most fundamentally reason leading to disablement of die after experimentation research, manufacture experience and stat. Thus, load and its action should be found out to improve life of die.In the second part which is main body, forging die's heat-force process is simulated by FEM(finite element method). Firstly, forging die's heat-force process is divided into alternate loop of decalescence process and heat-lossing process. The models of decalescence and heat-lossing are established. Exploring method is first put forward to get best working rhythm for heat balance of die. Temperature field of die is simulated under the rhythm. Secondly, temperature stress is solved by change of temperature field, and it is from heat load. Thirdly, machine stress is solved by machine load. Finally, integrated stress is gotten from temperature and machine stress added as time and space. Integrated stress can reflect really disablement reasons of die in microcosmic.In the third part, an example of final-die is investigated for heat-force process of die, and data about temperature field and several stress field are gotten. Die is divided into three parts, wave zone,balance zone and descending zone as change disciplinarian of temperature field, and thickness of wave zone is gotten by curve of overtaking-depth. It is concluded that disablement of die is mainly by temperature stress and disablement form is mainly plastic and thermal fatigue disablement from data of stress.In the last part, ways to improve life of die are grads material, consolidating surface, labrication and warm-up. If those reasons are consider, life of die is improved as best coupling state.