Engenharia Mecânica
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/23
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3 resultados
Resultados da Pesquisa
- Numerical and experimental modeling of thermal errors in a five-axis CNC machining center(2018) dos Santos M.O.; Batalha G.F.; Bordinassi E.C.; Miori G.F.© 2018, Springer-Verlag London Ltd., part of Springer Nature.This work aims at the establishment of methodology to model and analyze the thermal errors of a five-axis CNC machining center, from an estimated temperature field, to finally model an artificial neural network (ANN) algorithm to accurately predict with robustness the thermal error. The thermoelastic behavior of the machining center was modeled through two different approaches: experimental (or data-driven) model and numerical (or physical) model. The thermal behavior of the machine was first modeled using finite element method (FEM) techniques based on theory of friction heat and convection heat and validated with the various experimentally raised temperature fields using temperature sensors and thermal imaging. The main machine subsystems were initially validated, such as ball screw system, linear guides, and spindle, which allowed for validating of the thermal behavior of the entire machine for five different duty cycles obtaining a maximum error of less than 8% when comparing the numerical results with the experimental results. The components of the thermal errors in X, Y, and Z directions were obtained through FEM by measuring the displacement of the spindle tip in relation to the reference bushing located on the worktable. The same procedure was experimentally performed using a touch probe system clamped in the spindle, and the results were compared obtaining a maximum deviation of 17 μm. The validation of the finite element model allowed for the use of the results obtained by the simulation to train and validate an ANN for predicting the thermal errors of the machining center. The relative errors between the thermal errors predicted by the ANN and the FEM simulation results were less than 1% indicating that the methodology developed in this work that combines the use of physical models with data-driven models is an accurate and robust tool to predict the thermal errors of the machine for various working conditions, even with the machine moving at different speeds or alternating the movement of the axles.
- The sheet metal formability of AA-5083-O sheets processed by friction stir processing(2015) Miori G.F.; Bordinassi E.C.; Delijaicov S.; Batalha G.F.© 2015 G. F. Miori et al.The aim of this study is to determine the sheet metal formability of AA-5083-O sheets processed by the Friction Stir Processing (FSP). The FSP process was studied and a FSP tool was built. Processing quality was verified by the metallography in the processing region, which established the voids presence. Tensile tests were carried out on FSP and non-FSP specimens, and the results showed that FSP specimens have 30% greater resistance than non-FSP ones. The formability of FSP sheets was produced in MSC-MARC and Abaqus and these software products were compared by using the nonlinear FEM code. The Forming Limit Diagram was built with the results from both software products. A device to process FSP sheet metals was developed and the sheets were processed to validate the results from the software. The tools made for the bulge tests were circular and ellipse-shaped. After the bulge tests, the commercial sheets showed close approximation to those obtained from the software. The FSP sheets broke when inferior pressure was applied because of the defects in the FSP process. The results of the FSP presented the same formability of commercial sheets, however, with 30% greater strength.
- Surface integrity analysis in the super duplex stainless steel ASTM-A890 after machining(2008) Bordinassi E.C.; Stipkovic M.F.; Batalha G.F.; Delijaicov S.; De Lima N.B.The purpose of this paper was to study the main effects of the turning in the superficial integrity of the duplex stainless steel ASTM A890-6A. The tests were conducted on a turning centre with carbide tools and the main entrances variables were: tool material class, feed rate, cutting depth, cutting speed and cutting fluid utilisation. The answers were analysed: microstructural analysis by optical microscopy and x-ray diffraction, cutting forces measurements by a piezoelectric dynamometer, surface roughness, residual stress by x-ray diffraction technique and the microhardness measurements. The results do not show any changes in the micro structural of the material, even when the greater cutting parameters were used. The smaller feed rate (0.1 mm/v), smaller cutting speed (110 m/min) and the greater cutting depth (0.5 mm) provided the smaller values for the tensile residual stress, the smaller surface roughness and the greater microhardness. Copyright © 2008 Inderscience Enterprises Ltd.