| The vacuum heat treatment technology has the advantages of excellent comprehensivemechanical properties of workpiece, and makes it one of the main technologies of modernheat treatment technology.Research on vacuum heat treatment draws wide attention both at domestic and abroad,it can be seen that the popularization of heat treatment technology can give an index to alevel of national industry. But during the process of vacuum heat treatment, a series ofcomplex phenomena, such as internal heat transfer, inside deformation, internal stress andstrain of the workpiece with ambient medium, cannot be directly observed and measured.Along with the rapid development of computer technology and numerical computationmethod, numerical simulation can be used in the engineering application for the wholeprocess of production-manufacturing in order to discover potential problems in productionand manufacturing, and take steps to prevents them in the actual production, to ensure thesuccess rate of production, shorten the development cycle, and increase the competitivenessof products.Based on this background and structure characteristics of a certain type of vacuum gasquenching furnace, this paper is divided into two parts for vacuum gas quenching furnaceworking condition.The first part: heating stage in the vacuum gas quenching furnace.First three heat transfer modes were introduced, especially the unique characteristic ofradiation heating in vacuum furnace;Second, the vacuum furnace heating chamber working zone was defined and its evaluation standards were summarized.Finally, a simulation model of temperature field in vacuum furnace’s heating chamberis established. To realize the control standards for the temperature uniformity in furnace,thermocouples were arranged according to the nine point method. Due to the complexstructure in vacuum furnace, a numerical simulation software ANSYS was chosen formodeling and analysis. Finally, on the condition of keeping the fixed outer wall size andgood temperature uniformity, this paper optimized the size of working zone and obtainedthe maximum.The second part: for artifacts of high pressure gas quenching stage after heat insulation.First, the related control equation and general format of CFD was introduced. Thestandard k equation turbulence model were introduced, and its modified RNG k equation was obtained. Second, to simplify the modification of heating chamber model,FLUENT software for high pressure gas quenching process for flow field numericalsimulation analysis, and the individual artifacts (cylindrical metal material) cooling curve inquenching process were simulated, the influence of different pressures(0.1Mpa、0.2Mpa、0.5Mpa) on the cooling rate was studied, as to provide theoretical basis for the optimizationof quenching process. |
PDF Full Text Request