عنوان مقاله :
تخمين همزمان ضريب انتقال حرارت جابه‌جايي و شار حرارتي در عمليات فرزكاري
عنوان به زبان ديگر :
SIMULTANEOUS ESTIMATION OF HEAT FLUX INTO WORK PIECE AND CONVECTIVE HEAT TRANSFER COEFFICIENT IN MILLING PROCESS
پديد آورندگان :
داودآبادي فراهاني، سميه دانشگاه صنعتي اراك - گروه مهندسي مكانيك
كليدواژه :
عمليات فرزكاري , روش جست و جوي الگويي , روش اف‌مين سرچ , تخمين شار حرراتي , ضريب انتقال حرارت جابه‌جايي
چكيده فارسي :
در اين نوشتار به تخمين همزمان شار حرارتي ورودي به قطعه‌كار و ضريب انتقال حرارت جابه‌جايي در عمليات فرزكاري پرداخته شده است. دو مدل حرارتي صفربعدي و سه‌بعدي گذرا براي قطعه‌كار از جنس 13AISIH در نظر گرفته ـ شده است. دماها در پنج نقطه در داخل قطعه‌كار با استفاده از
ترموكوپل براي دو سرعت برشي mm/min50 و mm/min100 اندازه‌گيري شده است و براي تخمين مجهولات از روش جست و جوي الگويي و روش اف‌مين سرچ استفاده شده است. نتايج حاصل از دو مدل حرارتي براي مجهولات متفاوت و تقريباً مستقل از الگوريتم معكوس است. نتايج نشان مي‌دهد با افزايش سرعت برشي، شار حرارتي افزايش مي‌يابد و ضريب انتقال حرارت جابه‌جايي، در مدل حرارتي اول افزايش و در مدل حرارتي دوم كاهش مي‌يابد. همچنين هر دو
الگوريتم با دقت خوبي مقادير مجهول را بر اساس دماهاي اندازه‌گيري شده و مدل حرارتي برآورد كرده‌اند.
چكيده لاتين :
This study investigates the simultaneous estimation of heat flux input into a work piece and convective heat transfer coefficient in milling operations. Thematerial of the work piece is AISIH13. Temperatures in 5 points inside the work piece were measured using thermocouples(K-type). Two thermal models for the work piece were considered to solve the direct problem. Work piece material is an isotropic and the thermal property of work piece is constant. In the first thermal model, it is assumed that temperature changes only with time. This model uses the mean temperature of all thermocouples. For direct problem solving, the code of this model is written in MATLAB software. The second thermal model is a transient 3D problem and temperature inside work piece changes with time and location. This model uses the temperature of eachthermocouple. For direct problem solving, the code of this model is written in ANSYS software. Heat flux and convective heat transfer in two thermal models are unknown. Thus, the inverse heat transfer method is used to estimate the unknowns. This problem will not be solved by standard inverse algorithms. Thus, pattern search algorithm and Nealder-Mead method are used. For both of algorithms, MATLAB toolbox was used. In this study, two cutting speeds of: 50mm min and 100mm min were considered. The estimated values for of the unknowns by using two thermal models were different due to the assumptions are considered for models. The results obtained by two thermal models are independent of the inverse algorithms. The results show the heat flux input into the work piece as the cutting speed increases. Convective heat transfer coefficient increases with increasing the cutting speed in the first thermal model; however, this parameter decreases with increasing the cutting speed in the second thermal model. The main reason for this behavior is that, in the
second thermal model, the temperature gradient in all directions (XYZ) inside
the work-piece was considered. Estimated temperatures are in good agreement with measured temperatures.
عنوان نشريه :
مهندسي مكانيك شريف
