Baixe Rela...2013 - 02 relatorio para desempenho com comprovantes itens i e II e outras Provas em PDF para Engenharia Mecânica, somente na Docsity! UNIVERSIDADE FEDERAL DE ITAJUBÁ CAMPUS AVANÇADO DE ITABIRA RELATÓRIO PARA AVALIAÇÃO DE DESEMPENHO Período: de 08/03/2010 a 06/01/2014 Progressão: de Adjunto 1 para Adjunto 2 Prof.: Dr. Rogério Fernandes Brito SIAPE: 2498045 DOCUMENTOS ITEM I Ministério da Educação . UNIVERSIDADE FEDERAL DE ITAJUBÁ LEI 10.435, de 24 de Abril de 2002. Campus Universitário de Itabira ATESTADO ATESTO que o professor Rogério Fernandes Brito ministrou as seguintes disciplinas na instituição: No primeiro semestre de 2013: BAC 014 — Engenharia de Fluidos, Teórica (T3) de 80 horas/aula para 43 alunos. BAC 014 — Engenharia de Fluidos, Prática (PS) de 16 horas/aula para 20 alunos. BAC 014 — Engenharia de Fluidos, Prática (P6) de 16 horas/aula para 23 alunos. EME 016 — Máquinas de Fluxo, Teórica (T1) de 96 horas/aula para 23 alunos. EME 016 — Máquinas de Fluxo, Prática (P1) de 32 horas/aula para 23 alunos. Itabira, 19 de agosto de 2013. Diretor Acadêmico Unifei — Campus Itabira Responsável pelas informações: Naida Maria Fernandes Tito Vaz SIAPE: 1781335 Ministério da Educação . UNIVERSIDADE FEDERAL DE ITAJUBÁ LEI 10.435, de 24 de Abril de 2002. Campus Universitário de Itabira ATESTADO ATESTO que o professor Rogério Fernandes Brito ministrou as seguintes disciplinas na instituição: No segundo semestre de 2013: BAC 014 — Engenharia de Fluidos, Teórica (T5) de 80 horas/aula para 20 alunos. BAC 014 — Engenharia de Fluidos, Prática (PC) de 16 horas/aula para 25 alunos. BAC 014 — Engenharia de Fluidos, Prática (PD) de 16 horas/aula para 11 alunos. BAC 014 — Engenharia de Fluidos, Prática (PG) de 16 horas/aula para 19 alunos. BAC 014 — Engenharia de Fluidos, Prática (PH) de 16 horas/aula para 8 alunos. BAC 014 — Engenharia de Fluidos, Prática (PN) de 16 horas/aula para 11 alunos. BAC 014 — Engenharia de Fluidos, Prática (PJ) de 16 horas/aula para 9 alunos. EME 023 — Automação da Manufatura, Teórica (T1) de 12 horas/aula para 43 alunos. Ttabira, 12 de dezembro de 2013. ELA, ESA po Diretor Acadêmico Unifei — Campus Itabira Responsável pelas informações: Naida Maria Fernandes Tito Vaz SIAPE: 1781335 DOCUMENTOS ITEM II Thermal Analysis in TiN and Al2O3 Coated ISO K10 Cemented Carbide… 3 significant factors influencing the wear characteristics of electroless Ni-P coating were the annealing and bath temperatures. The aim of the present work is to numerically analyze how the coatings on cutting tools influence heat transfer during the cutting process. It is intended to verify the thermal and geometrical parameters of the coated tool, striving for a more adequate temperature distribution in the cutting region. In order to obtain the cutting tool temperature field, ANSYS CFX® Academic Research software v.12 was used. Additionally, a cutting tool with a single coating layer was used, as reported by Rech et al. (2005). In this work, eight cases were analyzed, all with cutting tools having a single layer coating, varying in thickness (h) from 1 µm to 10 µm. Different coating materials were investigated with two types of heat fluxes used on the tool-chip interface. The design of experiments (DoE) is used owing to the fact that it is the most economical and accurate method for performing process optimization. The DoE accelerates the understanding on the influence of the process parameters by determining which variables are critical to the process and at which level. This investigation required the evaluation of the effects of three variables (Montgomery, 2000). To ascertain the key relationships among them, DoE was used to find the best studied case of each simulation carried out. The temperature fields on the cutting tools were thus obtained. Finally, a numerical analysis of the thermal influence of these coatings is presented. 2. Problem Description Figure 1 presents the thermal model for heat conduction in a cutting tool and the regions for imposing boundary conditions. The tool geometry, within the computational domain, is represented respectively by Ω1 and Ω2, the coating solids of height h, the cutting tool substrate of height H, and interface C between the coating and the substrate. Only one type of material was considered for the cutting tool with dimensions 12.7x12.7x4.7 mm, with a nose radius R=0.8 mm and heat flux region S2 with an area of approximately 1.424 mm2. The coating thickness values adopted were: h=1 and 10 µm. (a) (b) Figure 1. Coated cutting tool: (a) interface detail and (b) heat flux region Rogério Fernandes Brito, João Roberto Ferreira et al. 4 At room temperature, the thermal parameters of the materials investigated (substrate and coating) were as follows: ISO K10 cemented carbide tool with density ρ=14,900 kg.m-3 (Engqvist et al., 2000), specific heat capacity Cp=200 J.kg-1.K-1 and thermal conductivity k=130 W.m-1.K-1 at 25 ºC (Engqvist et al., 2000), TiN coating with ρ=4,650 kg.m-3 (Yen et al., 2004), Cp=645 J.kg-1.K-1 (Yen et al., 2004) and k=21 W.m-1.K-1 at 100 ºC (Yen et al., 2004), Al2O3 coating with ρ=3,780 kg.m-3 (Yen et al., 2004), Cp=1,079 J.kg-1.K-1 (Yen et al., 2004) and k=28 W.m-1.K-1 (Yen et al., 2004). Figures 2a and 2b show one of the meshes formed by hexahedral elements and used in the numerical simulation. Figure 2c shows a typical contact area (A) on the tool-chip interface and the area used in the numerical simulation of the present work (A=1.4245 mm2). From Carvalho et al. (2006), the following cutting conditions were used: cutting speed of vc=209.23 m/min, feed rate of f=0.138 mm/rot, and cutting depth of p=3.0 mm. (a) Typical hexahedral mesh used. (b) Partial detail of the S2 heat flux region with A area in red color. (c) Video image of the S2 contact area on the chip-workpiece-tool interface (Carvalho et al., 2006). Figure 2. Non-structured mesh (a), mesh detail (b), image of the flux area (c). Thermal Analysis in TiN and Al2O3 Coated ISO K10 Cemented Carbide… 5 2.1. Boundary Conditions The present analysis assumed the following hypotheses: three-dimensional geometrical domain; transient regime; absence of radiation models; thermal properties, such as ρ, k, and Cp are uniform and the temperatures are independent for the coating layer and the substrate body; there is a perfect thermal contact and no thermal resistance contact between the coating layer and the substrate body; the boundary conditions of the heat flux q”(t) are uniform and the time is variable; the boundary conditions of the heat transfer coefficient h and room temperature T∞ are constant and also known; there is internal heat generation neither on the coating layer nor on the substrate body. The heat diffusion equation is subject to two types of boundary conditions: imposed time-varying heat flux in S2 and constant convection in S1 of the cutting tool. The initial temperature conditions are described for the thermal states of the substrate and coating solids as Ti=29.5 ºC. 3. Numerical Method The solution of the continuity, momentum, and energy equations uses the Fluid Dynamics Calculus using the Finite Volume Method (FVM) with Eulerian scheme for the spatial and temporal discretization of the physical domain, using a finite number of control volumes (Versteeg and Malalasekra, 2007 and Löhner, 2008). Through this method, the control volume elements follow the Eulerian scheme with unstructured mesh (Barth and Ohlberger, 2004). Using this approach, the transport equations may be integrated by applying the Gauss Divergence Theorem, where the approximation of surface integral is done with two levels of approximation. Firstly, the physical variables are integrated into one or more points on the control volume faces. Secondly, this integrated value is approximated in terms of nodal values. This approximation represents, with second order accuracy, the average physical quantity of all the control volume (Shaw, 1992). More details on the concepts involved in FVM may be found in Barth and Ohlberger (2004), where the authors explore discretization techniques, integral approximation techniques, convergence criteria, and calculus stability. 4. Numerical Validation The commercial software used here was validated extensively by comparing this work’s results of with those obtained in experimental and numerical investigations. For example, we compared our software’s numerically obtained temperatures with those obtained, both numerically and experimentally, by Carvalho et al. (2006). The largest deviation was 6.07 %. In most of the simulated cases, the number of nodal points was 501,768 and the number of hexahedral elements was 481,500. Rogério Fernandes Brito, João Roberto Ferreira et al. 8 t (s) 0 20 40 60 80 100 T (ºC ) 30 40 50 60 70 80 90 100 10 (µm) TiN coating with q1"(t) K10 substrate surface t (s) 0 20 40 60 80 100 T (ºC ) 100 200 300 400 500 600 10 (µm) TiN coating with q2"(t) K10 substrate surface (a) (b) Figure 6. Effect of heat flux variation on temperature (TiN coating with 10 µm thick) t (s) 0 20 40 60 80 100 T (ºC ) 40 60 80 100 10 (µm) Al2O3 coating with q1"(t) K10 substrate surface t (s) 0 20 40 60 80 100 T (ºC ) 40 60 80 100 1 (µm) Al2O3 coating with q1"(t) K10 substrate surface (a) (b) Figure 7. Effect of Al2O3 coating thickness variation on temperature with q1”(t) heat flux: (a) 10 µm thick and (b) 1 µm thick. t (s) 0 20 40 60 80 100 T (ºC ) 100 200 300 400 500 600 1 (µm) Al2O3 coating with q2"(t) K10 substrate surface t (s) 0 20 40 60 80 100 T (ºC ) 100 200 300 400 500 600 10 (µm) Al2O3 coating with q2"(t) K10 substrate surface (a) (b) Figure 8. Effect of Al2O3 coating thickness variation on temperature with q2”(t) heat flux: (a) 1 µm thick and (b) 10 µm. Thermal Analysis in TiN and Al2O3 Coated ISO K10 Cemented Carbide… 9 Figures 9a, 9b and 9c show the temperature fields at instant 63.14 s on the top and bottom of the insert and the heat flux surface, respectively, for case 4 (TiN coating with 10 µm). (a) (b) 785 785 78 5 785 785 785 78 5 785 785 785 797 797 797 797 797 797797797797797 797 810 810 797 810 810 810 810 810 797 810 810 835 810810 822 797 810 797 810 835 822 97822 8108228 2 822 847 8 2 810822822 847860 822822 822 835 847 835 847 835 860 835 847847 872 847 860 860872 847847 8608 72 (c) Figure 9. Temperature fields on: (a) top and (b) bottom and (c) heat flux surface (measured in K) on the TiN coated tool (case 4) at instant t=63.14 s. 5.1. Design of Experiment (DoE) The DoE was configured with 3 factors (thickness, heat flux and coating material) at two levels (-1 and +1) aiming to determine their influence on the temperature field. The coatings were TiN and Al2O3, the thickness values were 1 µm and 10 µm and the heat flux values were 1 and 10 times (Montgomery, 2000). Table 2 shows the parameters specified for the design of experiment. The experiments were planned and analyzed with the Minitab® Inc. v.14 software. Figure 10 shows the factors main effects on the temperature gradient (∆T). The best levels defined for the parameters are a TiN coating, coating thickness of 10 µm and heat flux of q2”(t). This combination presented the highest temperature gradient. Rogério Fernandes Brito, João Roberto Ferreira et al. 10 Table 2. DoE matrix. Trial no. Parameter Coating Thickness h µm Heat Flux Difference of temperature ∆T ºC 1 Al2O3 10 10 5.31 2 TiN 10 1 0.82 3 TiN 1 1 0.18 4 TiN 10 10 8.20 5 Al2O3 10 1 0.53 6 Al2O3 1 10 0.38 7 TiN 10 1 0.82 8 TiN 1 10 1.86 Al2O3TiN 4 3 2 1 0 101 101 4 3 2 1 0 Type of Coating M ea n of D iff er en ce o f Te m pe ra tu re Thickness of Coating Amount of Heat Flux Main Effects Plot (data means) for Difference of Temperature Figure 10. Influence of the main effects on the temperature gradient. 6. Conclusions One of the contributions of this work is its numerical approach. This methodology permits the simulations of complex geometrical forms. It also includes, relative to experimental cases, a more realistic heat flux (Carvalho et al., 2006). In addition to that, the following conclusions can be drawn regarding the numerical results obtained for the thermal model of heat transfer in coated cutting tools: • For a uniform heat source varying in time with constant surface contact between chip and tool, the coatings may slightly influence the temperature on the tool.