Simulation Implementation and Application Research of High Speed Milling Regeneration Type Chatter Based on MATLAB

Abstract

Considering the deficiency in milling process parameters selection in the domestic. Based on the modeling of dynamic milling force and the calculate of chatter stability limits. Realizing high speed milling regeneration type chatter simulation algorithm with Matlab development tools. Through the modal hammer experiment, Obtaining the frequency response function to simulate the chatter stability domain graphics of the whole processing system which can be used as an instruction guide for the selection of milling process parameters. The validation and accuracy of the simulation algorithm was verified by experiments and used in a factory with an excellent application effect. Introduction At present, the hardware condition and production performance of high precision and high speed is provided by advanced high speed milling machining center of domestic and foreign in theory, but these devices failed to play maximum processing capacity, the reason is that the relevant problems of mechanical vibration in actual production Machining process. The production practices show that the slight chatter leads to the quality decline of the machined surface, reducing the production efficiency, Bearing overload and shortening the life of main shaft. Heavy chatter leads to serious breakage of the cutter and damage of work piece and spindle. Therefore, the research of causes, rules and suppression methods in high speed milling chatter can effectively avoid the instability caused by vibration. this paper establishes regenerative type stability domain simulation flow chart of high speed milling and through the Matlab simulation algorithm for the analysis [7-9] . Selecting the stability parameters in order to avoid chatter , the simulation method has been applied in the factory and obtained the good application effect. Chatter Theory of High Speed Milling The Dynamic Model of Milling Force In High Speed Milling. The static milling force model without considering the effect of dynamic characteristic parameters in high speed milling, the cutting thickness of milling process was simply considered nonlinear relationship between feed rate and the instantaneous angle, ignoring the influence of vibration in milling process. Therefore, when the milling parameters change or workpiece vibration, the static milling force model can not descript about the true milling process, dynamics modeling has become an inevitable trend. The most critical for the dynamics modeling is the dynamic cutting thickness model, shown in Figure 1, expressed as: ) ( ) ( sin ) ( 0 0 jw jw jc jc j t j D u u u u f h − − − + = f f (1) The milling dynamic system is simplified as Spring damping mass model in vibration mechanics, considering the influence of the previous cutter tooth left by corrugated surface, Instantaneous rigid force model is used in cutting tool, the influence of static deformation force is neglected. The Dynamic milling force is obtained by accumulating algorithm. In the time domain model, milling force model for differential forms expressed as follows: International Industrial Informatics and Computer Engineering Conference (IIICEC 2015) © 2015. The authors Published by Atlantis Press 312 { } { } ) ( )] ( [ 2 1 ) ( t t A K a t F tc p ∆ = (2) In the formula A(T) is a periodic function of ω=NΩ, T=2π/ω. This formula is decomposed according to Fourier series will simplify the calculation mode. Budak and Altintas[10, 11] have been proved the effect of periodic function harmonics on forecasting precision can be neglected in practical application. So after the time-varying system is transformed by Fourier series, only the first term is reserved. The formula is as follows:       = = ∫ yy yx xy xx p a a a a N d A A ex st p f f f f f 2 )] ( [ 1 )] 0 ( [ (3) The simplified milling force coefficient introduces into dynamic milling force formula, further simplified as: { } { } ) ( ] [ 2 1 ) ( 0 t A K a t F t p ∆ = (4) Fig. 1 Schematic diagram of the dynamic cutting thickness The Chatter Stability Domain Algorithm. In the milling chatter stability analysis, Only considering the effects of dynamic milling force produced by the dynamic displacement of the tool and workpiece; The static part of the milling thickness is neglected.The main reason for the cutting depth and cutting direction changes is the periodic change of dynamic milling force coefficient matrix. Then the frequency response function of the tool and the workpiece is expressed as the following form: ) 2 ( ) ( ) ( ) ( ) 2 ( ) ( ) ( ) (