نوع مقاله : مقاله پژوهشی
نویسندگان
دانشکدهی مهندسی مکانیک، پردیس دانشکدههای فنی، دانشگاه تهران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Manufacturing of engineering components with precise dimensions are becoming quite important in attempts to reduce cost and improve reliability. In forging die design, dimensional accuracy is one of the main goals. The load carrying capacity and life of any forged product is greatly affected by its dimensional accuracy. To predict the precise dimension of the part and determine the die dimension for precision forging, it is necessary to analyze the factors which affect dimensional accuracy. For manufacturing a precision forging of turbine blades, thorough recognition of prevalent parameters is essential, such as preform design, process simulation and various techniques for compensation of errors due to die-elasticity characteristics. The accuracy of aerodynamic
cross-sections depends on many factors such as die elasticity, heat distortion and deformation of parts during the cooling of the die. The main goal of the design of aerodynamic section for the blade and its precision forging is to
minimize the machining process. By using finite element simulation; material flow analysis during the forging process, forging force in any moment, contact pressure distribution between die and workpiece, and also elastic deflection of forging dies, can be easily predicted. Therefore, for the compensation of die-elasticity, die shape should be changed through size modification. Most previous studies about blade forging simulation have been performed in 2D finite element, and with this simplification, errors due to die-elasticity characteristics have been compensated. Clearly the forging of a blade is a 3D process, and the blade does not have the same cross section along its length and hence the forging of the blade could not be considered a plane-strain process. In this research, commercially available software, DEFORM3D, was used for the purpose of finite element method simulation for the turbine blade forging. Using three dimensional finite element simulation, elasticity deflection of dies in different sections of a blade were obtained, and then the upper and lower die profiles of those sections in various directions were modified and errors due to die-elasticity compensated. Through these modifications, errors due to die elasticity were reduced to values less than those obtained in previous works. A series of multiple simulations for having an optimized compensation of the die-elasticity were carried out. Errors due to elastic deflection were also compensated by modifying the die position, based on elastic deflection magnitude.
کلیدواژهها [English]
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