دانلود رایگان ترجمه مقاله مدلسازی نیروها و ارتعاشات برشی استاتیک و دینامیک (نشریه الزویر 2013)

مدلسازی نیروها و ارتعاشات برشی استاتیک و دینامیک برای ابزارهای سرامیکی فرزکاری کارگذاری شده

Modeling Static and Dynamic Cutting Forces and Vibrations for Inserted Ceramic Milling Tools

Abstract

Cutting tools with ceramic inserts are increasingly being used in machining of super alloys typically used in aerospace industry. The ceramic inserts make higher cutting speeds possible due to the higher temperature resistance compared to carbide inserts. However, the success of the process is very sensitive to the right selection of process parameters. In this study, analytical process models for indexable milling tools with round ceramic inserts are presented. These models can be used to determine the cutting parameters for optimum quality and maximum productivity. Firstly, geometry of the insert cutting edges under the effect of angles on the inserts was formulated. Then, an analytical cutting force model was developed. This allows analyzing the effects of the parameters on the cutting forces. A time-domain model was also developed to analyze the dynamic cutting forces and stability limits for the milling process. Afterwards, the models were implemented in a Matlab® GUI to make the applications of the models in the industry easy. Cutting force coefficients, which are needed to calculate cutting forces, were identified from cutting tests with Inconel 718 material. Then, the cutting force model was validated with cutting experiments. After obtaining modal data of the tool via tap testing, dynamic cutting forces and vibrations were simulated by means of the time domain model. A series of simulations was carried out to determine stability limits at certain operating conditions using the time domain model, and stability lobes for the tools under study were plotted.

1 Introduction

Round ceramic inserts represent economic advantages over other type of inserts since higher material removal rate (MRR) is possible owing their high heat resistance and gradual entry to the cut. Analytical process models, that allow reliable predictions of cutting forces and machine-tool vibrations, facilitate the optimum process parameter selection, which is a challenge before making cutting tests. Main concerns are to control the cutting forces and to avoid chatter vibrations, as high and fluctuating cutting force magnitudes generally indicate chatter. This is the major limiting factor for increasing MRR, as it may cause severe machining problems [1]. Besides, power consumption and tool life are dependent on cutting force magnitudes.

Several researchers have been working in analytical, numerical and experimental models for predicting cutting forces and vibrations. In the past, the research was focused on modeling the mechanics and dynamics of standard end and face milling cutters with different geometries, such as cylindrical, ball-end and tapered. Indexable tools appeared in the mid-20th century. Fu et al. [2] presented pioneering work in the study of inserted face milling cutters. Engin and Altintas [3] developed a generalized mathematical model for inserted cutters, but it was experimentally validated for rectangular shapes. Recently, Altintas et al. [4] presented a unified cutting force model for inserted cutters that can be applied for different types of machining operations, but it is experimentally verified for straight line cutting edges too. Kim et al. [5] and Liu et al. [6] considered round cutting edges in the cutting force calculations which were experimentally verified, but the dynamic part of the forces was not taken into account.

In the next section, geometry of the cutting edge on the insert is described. In section 3, the cutting force model is detailed. The time-domain model is explained in section 4. In section 5, the verification of the static and dynamic forces with experimental data is exposed. Finally, stability analysis and conclusion are presented in section 6 and 7 respectively.