Stability analysis in milling of thin-walled workpieces with emphasis on the structural effect

2009 ◽  
Vol 224 (4) ◽  
pp. 589-608 ◽  
Author(s):  
X-J Zhang ◽  
C-H Xiong ◽  
Y Ding ◽  
X-M Zhang
Keyword(s):  
Stability Analysis ◽  
Great Influence ◽  
Structural Effect ◽  
Experimental Results ◽  
Machining Parameters ◽  
Chatter Stability ◽  
Milling Stability ◽  
Thin Walled ◽  
Five Axis ◽  
Milling Chatter

Regenerative chatter easily occurs in milling and has become the common limitation to achieve good surface quality and high productivity. For the purpose of chatter avoidance, the structural effect of the thin-walled part should be considered for the milling chatter stability analysis for the optimization of axial cutting depth and spindle speed pairs. The main objective of this paper is to examine the link between the structural modes (i.e. modal shapes) and the chatter stability limits in the case of finish milling thin-walled workpieces. In this paper, the dynamic stability of the milling process of thin-walled workpieces is investigated through a two-degree-of-freedom mechanical model. The mathematical relationship between the critical axial depth and the thin-walled part modal shapes is deduced and an optimal calculation process of milling stability lobes is presented. Peripheral milling of aluminium alloy (2A70 Al) plates is carried out on a computer numerically controlled (CNC) five-axis super high-speed machining centre to validate the method. The experimental results agree with the prediction by the presented method. Additionally, the experimental results show that the cutting stability is also influenced by the modal frequencies of the thin-walled part, which have a great influence on the milling stability analysis when the tool passing frequency (i.e. the inverse of the tooth passing period) harmonics are close to the modal frequencies of the part. The presented method is effective in the prediction of milling chatter limits in the thin-walled case for the optimization of machining parameters.

scholarly journals Experimental and simulation study on chatter stability region of integral impeller with non-uniform allowance

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042093341
Author(s):  
Yan Wu ◽  
Kaifa Wang ◽  
Gang Zheng ◽  
Boxin Lv ◽  
Yong He
Keyword(s):  
Natural Frequency ◽  
Stability Region ◽  
Tool Path ◽  
Surface Profile ◽  
Machining Process ◽  
Chatter Stability ◽  
Element Analysis ◽  
Impeller Blade ◽  
Five Axis ◽  
Milling Chatter

In order to accurately improve and predict chatter stability region of machining process, an optimization method of machining process with non-uniform allowance of integral impeller was proposed. The modal parameters of the workpiece process system were obtained using the finite element analysis. Based on the regenerative chatter analysis theory, a limit comparison diagram of the stability with uniform allowance and non-uniform allowance was established. The simulation results showed that the non-uniform allowance natural frequency is about 1.43 times as much as the uniform allowance natural frequency, and the machining system stiffness non-uniform allowance is twice as much as the uniform allowance, while the limit of chatter stability region is increased by 3 times. This article studied uniform allowance and non-uniform allowance of milling chatter stability with experimental method. Tool path for five-axis machining and machine tool simulation based on NX CAM were planned. The comparisons of cutting processing uniform allowance and non-uniform allowance were done, and the surface profile detection of the test part with the three-dimensional scanning was carried out. The experimental results showed that the average optimization rate for manufacturing precision of blade suction surface after optimization and pressure surface was 63.8% and 48.84%. The total experiment showed that this process optimization strategy could effectively improve the stiffness of the integral impeller blade and reduce the cutting chatter of the blade during the cutting process.

Milling stability analysis with considering process damping and mode shapes of in-process thin-walled workpiece

2019 ◽  
Vol 159 ◽  
pp. 382-397 ◽  
Author(s):  
Dongqian Wang ◽  
Michael Löser ◽  
Steffen Ihlenfeldt ◽  
Xibin Wang ◽  
Zhibing Liu
Keyword(s):  
Stability Analysis ◽  
Mode Shapes ◽  
Process Damping ◽  
Milling Stability ◽  
Thin Walled

scholarly journals Robust Chatter Stability Prediction of the Milling Process considering Uncertain Machining Positions

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Congying Deng ◽  
Wei Zhou ◽  
Kai Yang ◽  
Zhiyu Huang ◽  
Qian Tang
Keyword(s):  
Prediction Method ◽  
Modal Parameters ◽  
Stability Prediction ◽  
Chatter Stability ◽  
Milling Stability ◽  
Machining Allowance ◽  
Machining Parameter ◽  
Milling Chatter ◽  
Edge Theorem ◽  
Chatter Stability Prediction

Milling stability is a function of the tool point frequency response functions (FRFs), which vary with the movements of the moving parts within the whole machine tool work volume. The position-dependent tool point FRFs result in uncertain prediction of the stability lobe diagram (SLD) for chatter-free machining parameter selection. Taking the variations of modal parameters to represent the variations of tool point FRFs, this paper introduces the edge theorem to predict the robust milling chatter stability. The application of the edge theorem requires the minimum and maximum modal parameters within the machining space defined by the machining position and machining allowance information. Then, radial basis function artificial neural networks (RBFANNs) are used to predict the position-dependent modal parameters in X and Y directions based on the sample information of machining positions and related modal parameters at the tool point. Moreover, sample machining spaces are determined based on the aforementioned sample positions, and the trained RBFANNs are used to obtain corresponding sample extreme modal parameters. On this basis, RBFANNs for predicting the position and machining allowance-dependent extreme modal parameters can also be trained, and they are combined with the edge theorem and zero exclusion condition to calculate robust pairs of the spindle speed (n) and limiting axial cutting depth (aplim) and then plot the robust SLD (RSLD). A case study was performed on a real three-axial vertical machining center, and the plotted RSLD considering position variations was compared with the traditional SLD. Results of the chatter tests show that the RSLD can provide more reliable (ap, n) pairs to guarantee the milling stability, validating the feasibility of the proposed robust milling chatter stability prediction method.

FEA APPLICATIONS IN MILLING CHATTER STABILITY ANALYSIS

2005 ◽  
Vol 04 (01) ◽  
pp. 53-67 ◽  
Author(s):  
EYSION A. LIU ◽  
SIMON HO ◽  
MITCHEL WEHRLY ◽  
WILLIAM F. RESH
Keyword(s):  
Stability Analysis ◽  
Dimensional Accuracy ◽  
Dynamic Responses ◽  
Loop Model ◽  
Chatter Stability ◽  
Physical Test ◽  
Machining Forces ◽  
Novel Approach ◽  
Almost All ◽  
Milling Chatter

Regenerative chatter is a major hurdle to the productivity and quality of machining operations. This is because of the undesirable surface finish, excessive tool wear and deteriorated dimensional accuracy. Machining chatter analysis techniques examine the stability of a closed-loop model of machining forces and tool-workpiece system. This model is based on mathematical manipulations of machining forces and the dynamic responses of machining tooling. Almost all techniques derive the dynamic responses from physical test. In this paper, a novel approach of milling chatter stability analysis is introduced by using FEA applications to obtain the dynamic responses of the machine tool. The accuracy of this methodology is validated by machine shop tests.

Research on Milling Stability Using CNC Small Size Tool

2011 ◽  
Vol 199-200 ◽  
pp. 1993-1998
Author(s):  
Yong Xin Luo ◽  
Xiao Long Shen ◽  
Hua Long ◽  
Lai Xi Zhang
Keyword(s):  
Manufacturing System ◽  
Stability Domain ◽  
Mining Machine ◽  
Cnc Milling ◽  
Chatter Stability ◽  
Cutting Depth ◽  
Milling Stability ◽  
Cnc Milling Machine ◽  
The Stability ◽  
Milling Chatter

In a larger-power CNC milling machine, the milling stability of CNC small size tool which is less than φ 25 diameters is restricted under a certain degree. Authors studied CNC milling chatter stability by the experiment and simulation; they had researched those influences of tool’s diameter, suspended length and craft of manufacturing system on chatter stability domain. Researches show that the larger diameter and shorter suspended length of the tool can improve the stability of milling, and also can improve critical axial cutting depth. The lobes of chatter stability domain can forecast effectively critical axial cutting depth and relevant to milling speed, can better mining machine cutting potential.

Numerical Integration Method for Stability Analysis of Milling With Variable Spindle Speeds

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Ye Ding ◽  
Jinbo Niu ◽  
LiMin Zhu ◽  
Han Ding
Keyword(s):  
Differential Equation ◽  
Stability Analysis ◽  
Numerical Integration ◽  
Integration Method ◽  
Transcendental Equation ◽  
Spindle Speed ◽  
Machining Parameters ◽  
Numerical Integration Method ◽  
Stability Diagrams ◽  
Time Period

A semi-analytical method is presented in this paper for stability analysis of milling with a variable spindle speed (VSS), periodically modulated around a nominal spindle speed. Taking the regenerative effect into account, the dynamics of the VSS milling is governed by a delay-differential equation (DDE) with time-periodic coefficients and a time-varying delay. By reformulating the original DDE in an integral-equation form, one time period is divided into a series of subintervals. With the aid of numerical integrations, the transition matrix over one time period is then obtained to determine the milling stability by using Floquet theory. On this basis, the stability lobes consisting of critical machining parameters can be calculated. Unlike the constant spindle speed (CSS) milling, the time delay for the VSS is determined by an integral transcendental equation which is accurately calculated with an ordinary differential equation (ODE) based method instead of the formerly adopted approximation expressions. The proposed numerical integration method is verified with high computational efficiency and accuracy by comparing with other methods via a two-degree-of-freedom milling example. With the proposed method, this paper details the influence of modulation parameters on stability diagrams for the VSS milling.

Chatter Prediction Based on NC Physical Simulation in Machining Ti6Al4V Thin-Walled Components

2013 ◽  
Vol 395-396 ◽  
pp. 1008-1014
Author(s):  
Yu Li ◽  
Chao Sun
Keyword(s):  
Tool Path ◽  
Physical Simulation ◽  
Prediction Method ◽  
Cutting Parameters ◽  
Simulation Software ◽  
Cnc Machining ◽  
Machining Process ◽  
Chatter Stability ◽  
Chatter Prediction ◽  
Thin Walled

Chatter has been a problem in CNC machining process especially during machining thin-walled components with low stiffness. For accurately predicting chatter stability in machining Ti6Al4V thin-walled components, this paper establishes a chatter prediction method considering of cutting parameters and tool path. The fast chatter prediction method for thin-walled components is based on physical simulation software. Cutting parameters and tool path is achieved through the chatter stability lobes test and finite element simulation. Machining process is simulated by the physical simulation software using generated NC code. This proposed method transforms the NC physical simulation toward the practical methodology for the stability prediction over the multi-pocket structure milling.

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