پديد آورندگان :
خاتوني، آرمان نويسنده كارشناس ارشد دانشكده ي مهندسي مكانيك، پرديس دانشكده هاي فني، دانشگاه تهران Khatouni, A , ابري‌نيا، كارن نويسنده استاد دانشكده ي مهندسي مكانيك، پرديس دانشكده هاي فني، دانشگاه تهران Abrinia, K
چكيده فارسي :
با استفاده از شبيه‌سازي اجزا محدود مي‌توان آناليز جريان ماده در طول فرايند فورج، نيروي فورجينگ در هر زمان، توزيع فشار تماسي بين قالب و قطعه كار، و نيز خيز كشسان قالب‌هاي فورج را پيش‌بيني كرد. بنابراين براي جبران مقدار تغيير شكل كشسان قالب بايد شكل قالب را با استفاده از تغيير اندازه‌هاي آن اصلاح كرد. در اين تحقيق با استفاده از شبيه‌سازي اجزا محدود سه‌بعدي، خيز كشساني قالب در مقاطع مختلف پره به دست مي‌آيد و با اصلاح پروفيل‌هاي قالب بالايي و پاييني در اين مقاطع و در جهت‌هاي مخالف آن، خطاهاي ناشي از تغيير شكل كشسان قالب جبران مي‌شود. با استفاده از اين اصلاحات، خطاهاي ناشي از تغيير شكل كشسان به مقدار قابل ملاحظه‌يي كاهش خواهد يافت. براي جبران تغيير شكل كشسان قالب بايد چند‌بار شبيه‌سازي انجام داد تا خطاي ناشي از اين تغيير شكل كمينه شود.
چكيده لاتين :
Precise components 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 making a precision forging of turbine blades, thorough recognition of prevalent parameters is essential, like; preform design, simulation of processes, 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. The main goal of aerodynamic section production by 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 component, and also elastic deflection of forging dies, can be easily predicted. Therefore, for compensation of die-elasticity value, 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 compensated. As we know, the nature of forging a blade is a 3D process, and the blade does not have the same cross section along it, so, the forging blade process could not be considered a plane-strain process. In this research, a commercially available software, DEFORM3D, is used for the purpose of finite element method simulation of turbine blade forging. Using three dimensional finite element simulation, elasticity deflection of dies in different sections of a blade can be obtained, and, thereby, modifying upper and lower die profiles of those sections in various directions, errors due to die-elasticity can be compensated. Through these modifications, errors due to die-elasticity would be less than other dies. There would be a necessity of multiple simulations for having an optimized compensation of die-elasticity. Errors due to elastic deflection also would be compensated by modifying the die position, based on elastic deflection magnitude, accompanied by thinning the component design.
