Frequency Analysis of the Tool with and without Wear during Turning by Modal Analysis

Abstract

The stability of a cutting process directly influences the quality of a final surface. The control of the cutting process is an important problem for machining technology. Instabilities usually manifest as harmful chatter vibrations generated during cutting. Modal testing is a form of vibration testing which is able to determine the Frequency Response Function (FRF) of the mechanical test structures. In this context, we realized a study of vibration and of deformation between a tool without defect and a tool with two cases of defects. These defects have a random shape (any form), and the contact length tool-work piece, is considered the length of defects Lc=1 mm and the height of wear has been studied for two cases: VB=0.1 and 0.2 mm. In this paper, the main focus is creating a predictive model based on vibrations of body mass. The body mass mean the amount of material that constituting the cutting tool. The loss of a part of this mass makes the tool lighter; it increases the vibration of the tool. In addition to that, the Finite Element Method (FEM) modal analysis was used to obtain the natural frequencies. In this analysis we use ANSYS software based on (FEM), it is known for its high performance, quality and ability to solve all kinds of challenging simulations. The main idea is to create defects (wear) on the flank surface in order to create a model prediction. After the creation of defects, we start the modal analysis to study the deformation and the frequency of the tool. The results indicate that the frequency response and harmonic response analysis simulated by ANSYS with various defects created. First analysis is frequency response; we find the natural frequencies vary depending on the defect. When the tool is not defective we find the natural frequencies equal 337.77 Hz but in a tool with defects (VB=0.1-0.2 and 0.3 mm) we find the natural frequencies equal 340.36 Hz, 340.69 Hz and 341.11 Hz, this shows that the quality of the surface of the defect and its shape have an impact on the vibration of the tool. Then we based on a mathematical model to compare the results of the FEM where it shows a satisfactory correlation. In addition, the results of second analysis indicate that the deformation simulation by ANSYS with varying defects created. It increases with these defects: when VB=0.1 mm, we find that the maximum normal elastic deformation equal 0.16344 mm/mm and for VB=0.2 mm, we find that the maximum normal elastic deformation equal 0.16863 mm/mm, but for a new tool we find that the maximum normal elastic deformation equal 0.014976 mm/mm. This paper is designed to be beneficial for researcher’s engineers in manufacturing area In order to provide an advance vision about the vibration and the deformation evolution of the cutting tools when there are defects (wear) at tool tip.