(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.

r c C m c E t r d r

a f

w t

Proceedings of E Copyright © 201

In numeric resistance (TC contacting sur Commercial p method - was study. The he dimensions de


To obtain conventional l E1326B voltm temperature. T

The cuttin respective tool diameter and repeatability of


3. PROBLEM 3.1 Thermal M

The proble a shim position fix the set. A p

The transie where is th density, kg/m

The bound where T/ i tool and the wo

ENCIT 2014 4 by ABCM cal modeling, t CR) was chose rfaces, stemme package COMS used to solve eat diffusion e scribed in this experimental lathe IMOR M meter comman The experiment ng tool chosen l holder (code 7 m in len f the results. In gure 1. Experim

M DESCRIPTI Model Assemb em presented in ned under the c perspective is sh ent heat diffusi he solid therm m3.

dary conditions s the derivativ orkpiece. The h the boundary c en to analyze ed from the l SOL Multiphy a direct proble equation was u paper, as prev data, the exp MAXI I 520 nded by a co tal assembly is for the tests i ISSO CSBNR ngth were use n each test, 300 mental apparatus

ION bly n this work is s cutting tool be hown in Fig. 3 ion equation, w mal conductivit s have been giv ool-workpiece c ve along the no condition plays the impact up layer of air th ysics® v4.4 - u em with the pu used to define iously discusse periments were of 6 Horse P mputer, to w represented in is a cemented R 20K12). Gre ed as body of 0 temperature v s used to acquir (Carvalh shown in Fig. 3 tween the cutti .

which governs ven as: contact interfac ormal direction is applied to t

15 Br s a key role wh pon results. TC hat forms in t used to solve urpose of analy e the physics ed.

e carried out b ower HP, and which a K typ n Fig. 5. carbide tool (c ey cast iron bo f proof. Five e values were tak

3. This figure p ing tool and th the physical pr cp is the solid ce, n of the surface the contact are


razilian Congress hen utmost acc CR is a pheno the interstices heat transfer p yzing the impa problem of h by Carvalho e d a HP 75000 pe thermocoup code ISSO SN odies ABNT FC experiments w ken at a time in ure signals in th presents an ass he tool holder.

roblem of this d specific heat e of the set, an ea, W/m2:

curacy is desir omenon that o between two problems using act of TCR on heat transfer in et. al. (2006) a 0 B data acqui ple is connect

NUN 120412 H C 20 EB 126a were carried o nterval of 0.5 s.

e tool during m sembly consist There is also a work, is presen capacity, J/(k nd in the conta ences and Engin elém, PA, Brazil red. Thermal co occurs between o contacting b g the finite ele n the findings o n a model in at UFU, by us isition system, ted to measur

H1P – K10) an a, bearing 7 m out to guarante .

machining ing of a cutting a staple and a b nted below:

kg.K); is the act area betwee neering ontact n two bodies. ement of this three sing a , with re the nd the m in e the g tool, bolt to

(1) e solid

(2) en the

M p t r b m

c T

a d m a

Proceedings of E Copyright © 201 is applied in th The initial

3.2 Direct Pro

The transi

Multiphysics® purpose. The h this work, as p resistance on te the literature.

between the su m2/s (Incroper steel with the cutting tool’s p The shim was

Figure 2.

3.3 Numerica

The geom described in th


The indica and a significa described in th method was al analyzed in thi

ENCIT 2014 4 by ABCM he remaining re l conditions hav oblem Solution ent heat diffus v4.4 package, heat diffusion previously me emperature. Th

Simulation sc urfaces involve a et al., 2007).

following ther properties wer assigned the sa

Methodology u al Model etry used in th he experiments

3. a) set of too ation of the co ant source of e he literature, a lso used in our is study were o egions of the se ve been given sion equation is , which solves equation defin entioned. The b he TCR values cenarios consid ed. The therma The propertie rmal propertie e = 14900 k ame thermal pr used in the sim CO he simulations w run by Carval


ols, shim, and a ntact area of th rror in the solu and much has b r study. Althou obtained from o et, where h is th as:

s solved accord s thermal prob nes the physica boundary cond s applied to the dered the prop al properties a s considered fo kg m-3, cp = 19 roperties as the mulation for the OMSOL Multip was designed o ho et al. (2006 actual support t he cutting tool ution of the the been published ugh contact are only three tests

15 Br he heat transfe ding to the bou blems by usin al problem of h dition addresse e component pa perties of air a applied to air w or the material e cutting tool.

e tridimensiona physics® v4.4 p on commercial 6). Both are pre tool (Carvalho l is an importa ermal model p d on image an eas of various s performed un


razilian Congress er coefficient, ( undary conditio ng the Finite E heat transfer in ed in this stud arts of the mach at 300 K and were: = 0.02 ls involved wer al thermal mode package.

l software pack esented in Figu b o et al, 2006); b ant step in the d problem. Metho nalysis package shapes were s nder equal cutt ons defined ab Element Metho n a three dime dy is the effect hining equipm the existence

26 W m-1 K-1 a re: tool holder, el, in transient kage SolidWor ure 3.

b) b) model used i design of the e ods to identify es (Jen and Gu studied, the int ing conditions ences and Engin elém, PA, Brazil bove. The COM od, is used fo ensional model t of thermal co ment were taken of a gap of 1 and α = 2.5 x , made of AISI regime with th rks based on th in this study.

equipment geo y this area have utierrez, 2000) terface contact . Contact areas neering (3)


MSOL or this ling in ontact n from

10 m he he tool ometry e been . This t areas s were m 4 c a w m t o

i t u

K t

t e c

Proceedings of E Copyright © 201 measured with 450 MHz proc contact area m and a cut depth

Another im where tempera model to be si the thermocoup of the designed

Figure 4



This work in order to com them. The tran utilized as inp

K10 12.7 m thermo physica this present w elements, and constant and e 108.16 mm2.

ENCIT 2014 4 by ABCM h the aid of an i cessor, and im measured 1.41 m h 5.0 m. mportant facto atures were me imulated in ord uples in the des d geometry.

a 4. a) Contact ar sition/Thermoc x (m) y (m) z (m) k uses experim mpare with the nsient heat flu put data in the m × 12.7 m × al properties: λ work, the numb 1,712 edge ele equal heat tran According to imaging system age package G mm2 and was o or to be consid easured in the der to mitigate igned geometr


rea treated ima

Figure 5. Det Table 1. Lo mental tempera e numerical res ux was estimat present work.

ber of element ements. The fo nsfer coefficien this study, it m equipped wi GLOBAL LAB obtained at an dered in the m actual experim e the error emb ry. Table 1 sho ages (Carvalho tailed view of t ocation of the t ature results fr sults obtained b ted by Brito et The validatio late cemented

−1 K−1, cp = 332 ts utilized was ollowing param nt at 20 W m− is clear that

15 Br ith a Hitachi K B®. A typical c advance rate o modeling of the ment. Measurem bedded in the m ows the thermo o et at, 2006); a thermocouples thermocouples from Carvalho by the COMSO t. al. (2014), th n was conduc carbide cutting

2.94 J kg−1 K−1 s approximate meters were use −2 K−1, total tim there was litt


razilian Congress

KP-110 CCD ca contact area is of 0.138 m/re e studied geom ment points mu measured resul ocouple position b) and b) contact a welded to the shown in Fig.

et. al. (2006)

OL Multiphysi his heat flux is cted by using t g tool, as show

1, and ρ = 14,9 ly 119,943 do ed in the tests: me of 84.5 s, a tle difference amcorder, a PC shown in Figu ev, a cutting ra metry is the lo ust be accurate lts. Figure 5 sh ns in relation t area in the com tool. 5.

) under lab co ics® v4.4 packa s showed in th the thermal pr wed in figure 6

0 kg m−3. To omain element External temp and area subje as to the calc ences and Engin elém, PA, Brazil

C with an AMD ures 4a and 4b ate of 135.47 m ocation of the p ely positioned hows the posit to the point of mputer model.

ontrolled cond age so as to va he figure 7, and roperties of the , with the follo obtain the resu ts, 19,152 bou perature at 31.0 ected to heat fl culated tempe neering

D® K6 b. The m/min, points in the ion of origin ditions alidate d was e ISO owing ults in undary 06 °C, flux of erature v i c b t p c C e e

Proceedings of E Copyright © 201 values. Moreo is concluded computational barely varies tool when com


In this sec presented. The considering ai Carvalho et. al each temperatu experimental t

Figure 6. Sc

Figure 8. Co present w

ENCIT 2014 4 by ABCM over, the tempe that the num time simulati with mesh r mpared to the p ction, the resul e proprieties of ir for the thic l. (2006). The ure monitoring emperatures an chematic repre apparatus us omparison betw work without co erature residue mber of eleme ons. For a me efinement. Th physical results ts of one of th f the thermal c ckness of 10. data obtained g point, the fi nd the second w esentation of th sed in validatio


ween experimen ontact thermal e among the m ents of the m esh developed he COMSOL s obtained by C he eight monito contact resistan 0 µm was th from the simu irst with the te with the tempe he experimenta on.

ntal data (Carv resistance a) a

15 Br meshes is pract mesh is alread with a greate software prov Carvalho et. al ored temperatu nce between th he thermal con ulations were p emperatures ob eratures obtaine al Figure valho et. al., 20 and with contac


razilian Congress tically negligib dy enough to er number of ved satisfactory . (2006).

(Parte 1 de 2)