Investigation on Adaptive Filter for On-Line Detection and Active Control of Chatter Vibration in Milling Process

2019 ◽  
Author(s):  
Shaoke Wan ◽  
Xiaohu Li ◽  
Wenjun Su ◽  
Jun Hong
Keyword(s):  
Active Control ◽  
Adaptive Filter ◽  
Rotation Frequency ◽  
Milling Process ◽  
Spindle Speed ◽  
Line Detection ◽  
Spindle Rotation ◽  
On Line ◽  
Milling Chatter ◽  
Periodic Components

Abstract On-line detection and active control of chatter vibration have always been important issues in milling process respectively. To some extent, the signals obtained with sensors determine the performance of on-line detection and active control of chatter. However, due to the characteristics of milling process, the obtained signals are mainly consisted with spindle rotation frequency and its harmonics, and the chatter components are usually submerged by these stable harmonics, imposing negative effects for the detection and active control of milling chatter. Then, it is highly needed to design a real-time filter to filter out the spindle rotation frequency and its harmonics. In this paper, an adaptive filter is designed to filter out the spindle speed related components. Moving average (MR) model and adaptive filter theory is utilized to estimate these periodic components. The influence of filter order and step size factor on the filter characteristics are also analyzed. Considering that the filter order needs to be adjusted under different cutting conditions, which will alter the filter’s performance, an improved adaptive filter is proposed. Experiments are also performed and the experimental results show that, not only the spindle speed related components can be filtered out effectively, but the chatter frequency components are amplified with appropriate initial step factor, which is beneficial for the detection of milling chatter at early stage. Meanwhile, the periodic components caused by the installation error and the other spindle speed related components can be effectively filtered out real-timely, preventing the saturation of actuator caused by these stable components.

The Effect of Multiple Dynamic Absorbers on Regenerative Chatter and Resonance in End Milling Process

2012 ◽  
Author(s):  
Yutaka Nakano ◽  
Hiroki Takahara ◽  
Kengo Yasue ◽  
Ryutaro Asaga
Keyword(s):  
Natural Frequency ◽  
Phase Difference ◽  
Forced Vibration ◽  
End Milling ◽  
Rotation Frequency ◽  
Spindle Speed ◽  
Depth Of Cut ◽  
Critical Depth ◽  
Spindle Rotation ◽  
Critical Depth Of Cut

The present study investigates the effect of multiple dynamic absorbers on regenerative chatter and resonance caused by forced vibration generated in the end milling operations. Regenerative chatter is caused by the cutting force variation due to the phase difference between the wave left by the previous cutting edge and the wave left by the current one. This phase difference is expressed as the product of the tooth passing period and chatter frequency [1]. The tooth passing period depends on the spindle rotation frequency and the number of teeth. Chatter frequency is related to the natural frequency of the tool and spindle system. If the integral multiple of the spindle rotation frequency approaches to the natural frequency, the phase difference gets smaller and the critical depth of cut at the onset of chatter is increased. Therefore the critical depth of cut varies with the spindle speed and stable cutting conditions are plotted on the chatter stability lobe, which is a chart that represents the boundary between stable and unstable cuts as a function of the spindle speed and the depth of cut. The chatter stability lobe is widely employed to find the axial depth of cut and the spindle speed in which chatter doesn’t occur. Meanwhile, the cutting force variation by the intermittent cutting with an end milling tool causes the forced vibration. The excitation frequency is determined by the spindle rotation frequency and the number of teeth. When the integral multiple of the excitation frequency approaches to the natural frequency of the tool and spindle system, resonance can be caused by the forced vibration. The resonance occurs in the spindle speed resistant to chatter. Therefore, there is a need for a countermeasure against not just the chatter but also the resonance caused by the forced vibration. In the present study, the cutting conditions which can lead to the chatter and the resonance are investigated by the direct numerical integration method. It is made clear that the optimum tuning parameters of the absorbers to maximize the critical depth of cut vary with the spindle speed. Furthermore, a significant suppression effect on the chatter and the resonance by using the absorbers mounted in a rotating collet holder with a spindle is confirmed.

scholarly journals Stability Analysis of Milling Process with Variable Spindle Speed and Pitch Angle considering Helix Angle and Process Phase Difference

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Gang Jin ◽  
Haotian Jiang ◽  
Jianxin Han ◽  
Zhanjie Li ◽  
Hua Li ◽  
...  
Keyword(s):  
Phase Difference ◽  
Pitch Angle ◽  
High Speed ◽  
Helix Angle ◽  
Stability Domain ◽  
Milling Process ◽  
Spindle Speed ◽  
The Stability ◽  
The Time Domain ◽  
Milling Chatter

Suppression of milling chatter by disrupting regenerative effect is a well-known method to obtain higher cutting stability domain. In this paper, a dynamic model of the milling process with variable spindle speed and pitch angle considering helix angle and process phase difference is presented. Then, an updated semidiscretization method is applied to obtain the stability chart. After the effectiveness of the proposed method is confirmed by comparisons with the previously published works and the time-domain simulations, lots of analyses are conducted to deeply evaluate the influence of the helix angle, the process phase difference, and feed per tooth on milling stability. Results show that the change of helix angle can result in significant stability discrepancies for both high-speed and low-speed regions. Though the process phase difference has the randomness and immeasurability in the practical application, it has an important influence on the stability and will result in a periodic evolution of the stability with a period π. Also, its recommended values are given for the practical milling process.

The Dynamic Analysis of Micro-Scale Edge in the Process of Micromilling

2013 ◽  
Vol 797 ◽  
pp. 628-637
Author(s):  
Ya Dong Gong ◽  
Jin Feng Zhang ◽  
Jun Cheng ◽  
Xue Long Wen ◽  
Chao Wang ◽  
...  
Keyword(s):  
Fourier Method ◽  
Milling Process ◽  
Spindle Speed ◽  
Micro Milling ◽  
Theoretical Research ◽  
Actual Case ◽  
Micro Scale ◽  
Machined Parts ◽  
Micro Tool ◽  
Milling Chatter

The micro-processing technology has gradually become a hot topic problem, especially in micro-scale milling chatter prevention with the development of the information age. In allusion to the actual case of micro-milling, the dynamic theoretical research is analyzed in-depth about the Fourier method and the average tooth angle method. Compared to two ways, the former is close to the actual processing requirements. The lobes are obtained use the two ways. Micro milling parameters are selected in the stable area and unstable region. Stable and non-stable curve and surface quality of machined parts are obtained after micro-milling test. The chatter points, non-chatter point and uncertain point are obtained in the high spindle speed, which are consistent with theoretical analysis. In contrast, the distribution of chatter points in the low-speed spindle speed. The reason is that the damping effect is produced in the micro-scale milling process. The research of micro-scale milling chatter, which has a certain significance to improve parts of precision machined parts, reduce the wear and tear of the micro-milling blade and extend micro-tool life.

Chatter prevention and improved finish of workpiece for a milling process

2009 ◽  
Vol 224 (4) ◽  
pp. 579-588 ◽  
Author(s):  
N-C Tsai ◽  
D-C Chen ◽  
R-M Lee
Keyword(s):  
Real Time ◽  
Acoustic Signal ◽  
Milling Process ◽  
Spindle Motor ◽  
Spindle Speed ◽  
Feedback Signal ◽  
Motor Speed ◽  
Acoustic Feedback ◽  
The Stability ◽  
Milling Chatter

This paper presents how real-time chatter prevention can be realized by feedback of an acoustic cutting signal. The efficacy of the proposed adaptive spindle speed tuning algorithm is verified by intensive experimental simulations. A pair of microphones, perpendicular to each other, is used to acquire the acoustic cutting signal resulting from milling chatter. A real-time feedback control loop is constructed for spindle speed compensation in such a way to ensure that the milling process is within the stability zone of the stability lobe diagram. The acoustic chatter signal index (ACSI) and the spindle speed compensation strategy (SSCS) are proposed to quantify the acoustic signal and actively to tune the spindle speed respectively. By converting the acoustic feedback signal into the ACSI, an appropriate spindle speed compensation rate (SSCR) can be determined by the SSCS based on a real-time chatter level or the ACSI. Accordingly, the compensation command, referred to as added-on voltage (AOV), is applied to increase/decrease the spindle motor speed. By employing the commercial software MATLAB/Simulink and the dSpace DS1104 interface module to implement the controller, the proposed chatter prevention algorithm is practically verified by intensive experiments. By inspection on the precision and quality of the workpiece surface after milling, the efficacy of the real-time chatter prevention strategy via acoustic signal feedback is further assured.

On-Line Energy-Based Milling Chatter Detection

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Hakan Caliskan ◽  
Zekai Murat Kilic ◽  
Yusuf Altintas
Keyword(s):  
Fourier Transforms ◽  
Energy Operator ◽  
Forced Vibrations ◽  
Chatter Detection ◽  
Line Energy ◽  
Natural Modes ◽  
Chatter Vibrations ◽  
On Line ◽  
Milling Chatter ◽  
Periodic Components

Milling exhibits forced vibrations at tooth passing frequency and its harmonics, as well as chatter vibrations close to one of the natural modes. In addition, there are sidebands, which are spread at the multiples of tooth passing frequency above and below the chatter frequency, and make the robust chatter detection difficult. This paper presents a novel on-line chatter detection method by monitoring the vibration energy. Forced vibrations are removed from the measurements in discrete time domain using a Kalman filter. After removing all periodic components, the amplitude and frequency of chatter are searched in between the two consecutive tooth passing frequency harmonics using a nonlinear energy operator (NEO). When the energy of any chatter component grows relative to the energy of forced vibrations, the presence of chatter is detected. The proposed method works in discrete real time intervals, and can detect the chatter earlier than frequency domain-based methods, which rely on fast Fourier Transforms. The method has been experimentally validated in several milling tests using both microphone and accelerometer measurements, as well as using spindle speed and current signals.

A Model Based Computationally Efficient Method for On-Line Detection of Chatter in Milling

2013 ◽  
Author(s):  
Lei Ma ◽  
Shreyes Melkote ◽  
James Castle
Keyword(s):  
Efficient Method ◽  
Chip Thickness ◽  
Line Detection ◽  
Chatter Detection ◽  
Computationally Efficient ◽  
Model Based ◽  
Force Signal ◽  
On Line ◽  
Regeneration Effect ◽  
Milling Chatter

This paper presents a model-based computationally efficient method for detecting milling chatter in its incipient stages. Based on a complex exponentials model for the dynamic chip thickness, the chip regeneration effect is amplified and isolated from the cutting force signal for early chatter detection. The proposed method is independent of the cutting conditions. With the aid of a one tap adaptive filter, the proposed method is also found to be able to distinguish between chatter and the dynamic transients in the cutting forces due to sudden changes in workpiece geometry and tool entry/exit. The proposed method is experimentally validated.

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