Encit2014-239

Encit2014-239

(Parte 1 de 2)

Copyright © 2014 by ABCMNovember 10-13, 2014, Belém, PA, Brazil

Proceedings of ENCIT 2014 15 Brazilian Congress of Thermal Sciences and Engineering

Samuel Souza Silva, samuelsilvalagoa@gmail.com

Rogério Fernandes Brito, rogbrito@unifei.edu.br Universidade Federal de Itajubá - UNIFEI, Rua Irmã Ivone Drummond, 200, Distrito Industrial I, CEP 35903-087, Itabira, MG, Brasil

Sandro Metrevelle Marcondes de Lima e Silva, metrevel@unifei.edu.br Universidade Federal de Itajubá - UNIFEI, Instituto de Engenharia Mecânica - IEM, Laboratório de Transferência de Calor - LabTC, Av. BPS, 1303, Bairro Pinheirinho, CEP 37500-903, Caixa Postal 50, Itajubá, MG, Brasil

Abstract. This paper presents the results of simulations in heat transfer by using the commercial software COMSOL Multiphysics® v4.4. The differential equations are solved by using Finite Elements Method existent on this commercial package. These simulations are based on controlled experiment carried out in the Heat Transfer Laboratory of the Federal University of Uberlândia (UFU), in Brazil. The main goal of this study was to investigate the impact of thermal contact resistance on temperature. Thermocouples were inserted on many surfaces in order to measure experimental temperatures. In past work, the heat flux was estimated by Inverse Problems technique by the authors of the present work. By using the estimated heat flux, simulation was performed to calculate the temperatures on equivalent monitored experimental points. Two simulations were done, one considering thermal contact resistance between the cutting tool, the shim and the workpiece and another in which the contact resistance was disregarded. The results between these two simulations were compared. This work presents better results for the calculated temperatures with contact resistance than those presented in literature.

Keywords: heat conduction, COMSOL Multiphysics® v4.4 package, air resistance, cutting tool 1. INTRODUCTION

The research related to basic studies of industrial processes always enables the development of manufacturing operations not only as locally but also on a global scale. Therefore, since the machining process is used in most productive segments, it is important to treat the parameters which lead its scientific principles and technological innovations. Treating the analysis of the distribution of temperature field, as well as the study of heat flow in cutting tools during machining operations is a task that requires complex methods to obtain reliable data on each process. This is due to the fact that machining processes involve high temperatures and it is difficult to measure this parameter in the wear region. Temperatures may exceed 900°C in the cutting tool (Trent and Wright, 2000). Thus, the precise estimation of this temperature leads to numerical procedures in order to establish a research to optimize the use of cutting tools providing improvement in their performance and durability. By studying the characteristics of the cutting tool adopted, it is possible to prove that the use of inserts is a way to alleviate the stresses arising from the operations of milling, boring, turning, etc. Furthermore, these analyses aim to increase the life of cutting tools as can be seen in Smith (2011) who made a study about the cutting conditions to extend tool life and show some of the problems that reduce it and show high temperatures as a big problem. Yang et. al. (2011) shows a similar study, where the performance of the tool was enhanced, reducing production costs and increasing industry’s profit. Therefore, it allows, through numerical studies, an increase in cutting speed and a reduction in the use of lubricants and refrigerants, optimizing the time in the industry and minimizing impacts on the environment.

Based on this information, the authors of this paper used a software package and proposed a numerical analysis to assess the impact of the thermal contact resistance existing between the parts of the cutting tool, shims, and tool holder on the temperatures observed in a machining process. The issues addressed in this paper were partly discussed by Carvalho et al. (2006), in a study that analyzed the high temperatures generated in chip-tool interface during machining processes. Brito et al. (2014) used the experimental results from Carvalho et al. (2006) to estimate the heat flux, since direct measurement of heat flux is difficult to implement due to the difficulty of positioning the thermocouples on chip -tool interface, heat flux was used as input in the numerical simulations presented in this paper. With the heat flux in question the temperatures were obtained by using the Finite Element Method as in the study of Chen et al. (2013). The numerical location of the thermocouples described by Carvalho et al. (2006) was included in the numeric simulations, so that numerical and experimental results were subsequently compared. This work aims to show the results of simulations that were performed in the geometry, shown in Fig. 3, analyzing the thermal impact of different boundary conditions over the final result. However, as a part of a scientific academic research, this work analyzes only the heat transfer in the assembly studied. Thermal contact resistance (TCR) was considered as the boundary condition.

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5. ANALYSIS

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(Parte 1 de 2)

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