نوع مقاله : مقاله پژوهشی
نویسنده
گروه مهندسی مکانیک،دانشگاه صنعتی اراک
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسنده [English]
This study investigates the simultaneous estimation of heat flux input into a
work piece and convective heat transfer coefficient in milling operations. The
material 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 each
thermocouple. 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.
کلیدواژهها [English]
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