Chatter Suppression in Milling: An Active Approach

1999 ◽  
Author(s):  
Douglas R. Browning ◽  
Igor Golioto ◽  
Norman B. Thompson
Keyword(s):  
The Body ◽  
Active System ◽  
Tool Holder ◽  
Chatter Suppression ◽  
Cutting Test ◽  
Active Approach ◽  
Chatter Control ◽  
Control Electronics ◽  
Drive Signals ◽  
Milling Chatter

Abstract A new approach to chatter control in milling is presented in this paper. The proof-of-concept control system comprises a tool holder, analog and digital control electronics, and power amplifiers to drive the actuator elements. The active tool holder, designed to impart counter-vibration forces to the milling tool, mounts to existing machines with a standard industrial interface. Sensors and piezoelectric actuators are imbedded in the stationary portion of the tool holder and are therefore fixed relative to the body of the milling machine. The controller operates on the two sensor signals, producing two orthogonal actuator drive signals to oppose resonant tool vibrations induced from the cutting forces. The paper first introduces the fundamental concepts of milling chatter and their relation to the described active system. The actuation, sensing and controller details follow. The influence of the tool holder on system dynamics and cutting stability is also addressed. Cutting test results using a titanium alloy are then described, demonstrating an improvement of a factor of five in surface finish relative to the uncontrolled, chatter-dominated case.

Numerical Solution of Tuned Mass Dampers for Optimum Milling Chatter Suppression

2011 ◽  
Vol 697-698 ◽  
pp. 223-228
Author(s):  
Yi Qing Yang ◽  
T.T. Chen
Keyword(s):  
Vibration Suppression ◽  
Numerical Approach ◽  
Harmonic Excitation ◽  
Complex Problem ◽  
Depth Of Cut ◽  
Tuned Mass Dampers ◽  
Chatter Suppression ◽  
Machine Tool Chatter ◽  
Chatter Control ◽  
Milling Chatter

The most common tunings for the TMD in the field of vibration suppression are H∞ and H2. However, regenerative machine tool chatter is a complex problem with many variations, which therefore requires a new tuning for the optimum chatter suppression. The real part based tuning is investigated numerically by employing the minimax numerical approach, which aims to maximize the minimum real part of the primary structure under the harmonic excitation. The performances of multiple TMDs system are discussed. A face milling case is employed to verify the benefits of multiple TMDs in increasing the chatter free depth of cut. It is concluded that multiple TMDs configuration are more effective than single TMD in chatter control.

Use of Audio Signals for Chatter Detection and Control

1992 ◽  
Vol 114 (2) ◽  
pp. 146-157 ◽  
Author(s):  
T. Delio ◽  
J. Tlusty ◽  
S. Smith
Keyword(s):  
Frequency Domain ◽  
End Milling ◽  
Practical Implementation ◽  
Chatter Detection ◽  
Short Contact Time ◽  
Cutting Test ◽  
Displacement Sensors ◽  
Chatter Control ◽  
And Control ◽  
Low Radial Immersion

This paper compares various sensors and shows that a microphone is an excellent sensor to be used for chatter detection and control. Comparisons are made between the microphone and some other common sensors (dynamometers, displacement probes, and accelerometers) regarding sensing of unstable milling. It is shown that the signal from the microphone provides a competitive, and in many instances a superior, signal tht can be utilized to identify chatter. Using time domain milling simulations of low-radial-immersion, low-feed, finishing operations it is shown that for these cuts (especially at relatively high speeds) chatter is not adequately reflected in the force signal because of the short contact time, but that it is clearly seen in the displacement signal. Using the dynamics of existing production milling machines it is shown how the microphone is more suitable to chatter detection than other remotely placed displacement sensors, especially in cases that involve flexible tooling and workpieces. Aspects important for practical implementation of a microphone in an industrial setting are discussed. Limitations of the microphone are addressed, such as directional considerations, frequency response, and environmental sensitivity (i.e., workspace enclosure, room size, etc). To compensate for expected unwanted noises, commonly known directionalization techniques such as isolation, collection, and intensity methods are suggested to improve the ability of the microphone to identify chatter by reducing or eliminating background and extraneous noises. Using frequency domain processing and the deterministic frequency domain chatter theory, a microphone is shown to provide a proper and consistent signal for reliable chatter detection and control. Cutting test records for an operating, chatter recognition and control system, using a microphone, are presented; and numerous examples of chatter control are listed which include full and partial immersion, face-and end-milling cuts.

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

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Lei Ma ◽  
Shreyes N. Melkote ◽  
James B. Castle
Keyword(s):  
Cutting Force ◽  
Efficient Method ◽  
Frequency Estimation ◽  
Chip Thickness ◽  
Computationally Efficient ◽  
Model Based ◽  
Chatter Suppression ◽  
Force Signal ◽  
Regeneration Effect ◽  
Milling Chatter

This paper presents a model-based computationally efficient method for detecting milling chatter in its incipient stages and for chatter frequency estimation by monitoring the cutting force signals. 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 method is shown to be capable of distinguishing between chatter and the dynamic transients in the cutting forces arising from sudden changes in workpiece geometry and tool entry/exit. To facilitate chatter suppression once the onset of chatter is detected, a time domain algorithm is proposed so that the dominant chatter frequency can be accurately determined without using computationally expensive frequency domain transforms such as the Fourier transform. The proposed method is experimentally validated.

scholarly journals CONTEMPORARY ISSUES AND THE WAYS OF ENSURING ELECTROMAGNETIC SAFETY OF MOBILE COMMUNICATION TO THE HEALTH OF THE POPULATION

2019 ◽  
Vol 98 (11) ◽  
pp. 1175-1183
Author(s):  
Yury A. Rakhmanin ◽  
G. G. Onishchenko ◽  
Yu. G. Grigoriev
Keyword(s):  
Mobile Communication ◽  
Negative Impact ◽  
The Body ◽  
Base Stations ◽  
Critical Groups ◽  
Electromagnetic Environment ◽  
Active System ◽  
Reduce Radiation Exposure ◽  
The Central Nervous System ◽  
Frequency Modulations

There was performed an analysis of the literature data on the characteristics and dynamics of changes in the electromagnetic environment associated with the uncontrolled intensive development of cellular communications, as the most active system for the formation of mobile communication tools related with electromagnetic fields (EMF) created by non-ionizing radiation (NIR) as base stations and subscriber terminals (ST). It is summarized the main medico-biological features of the influence of EMF radio frequency range (RFR) on the body and patterns of the formation of the density of the flow of energy (DFE) NIR. There are considered the main principles of the formation of regulatory base underlying in the basis of ensuring biosafety these funds in Russian Federation (RF) and abroad, including influence on the central nervous system (CNS) and remote consequences, in particular on cancergenezis, as well as grounds for their adjustments and modernization. Special attention is paid to the negative impact of EMF RFR on critical groups of the population, first of all, children. There are given ways of reducing the intensity of the RFR, creating conditions to reduce radiation exposure by users. There was performed comparison of frequency modulations means of mobile communication with the frequency characteristics of organ and intracellular functional systems of the human body. It’s presented goal, tasks and measures for the project foundations of the conception of EMS of the RF for the period to 2025, developed based on the hearings as of problems in the Committee on social policy at the Council of the Federation, held in 2017-2018 years.

Chatter Suppression with Magnetic Damping in Turning of Stainless Steel AISI 304

2013 ◽  
Vol 393 ◽  
pp. 183-188 ◽  
Author(s):  
Ummu Atiqah Khairiyah B. Mohammad ◽  
A.K.M.N. Amin ◽  
Muhd Amir Hafiz Bin Ahamad Mahrodi ◽  
Muammer D. Arif
Keyword(s):  
Magnetic Field ◽  
Stainless Steel ◽  
Permanent Magnet ◽  
Surface Finish ◽  
Machining Accuracy ◽  
Aisi 304 ◽  
Tool Holder ◽  
Chatter Suppression ◽  
Steel Aisi ◽  
Stainless Steel Aisi

Chatter is almost an unavoidable phenomenon during machining, normally accompanied by a characteristic sharp and monotonous noise. Apart from noise pollution in the industry, chatter leaves a bad surface finish on the part and negatively influences dimensional tolerances, reduced productivity, excessive tool wear and damaged machine-tool components. Therefore, chatter avoidance is utmost importance. However, a deeper investigation into chatter formation reveals that chatter appears during metal cutting process as a result of resonance caused by interaction of the prominent natural frequencies of the system with the frequency of chip serration. This paper presents an innovative approach to chatter suppression during turning of stainless steel AISI 304 applying permanent magnet from the bottom of the tool holder to increase the damping coefficient of the tool holder, since it has been identified that the tool holder is the main vibrating component during turning. A special fixture was designed, fabricated and mounted on the carriage of a conventional turning machine Harrison M390 for holding a permanent magnet bar. The variable cutting parameters were - cutting speed, feed rate and depth of cut at constant tool overhang of 120 mm. The experiments were designed based small Central Composite Design (small CCD) based on the Response Surface Methodology (RSM) approach using DESIGN EXPERT (DOE) software. The experiments were performed under two different conditions, the first under normal conditions, while the other was under the application of magnetic field from permanent magnet located side direction of the tool holder. The experiments focused on monitoring the vibration signals using a vibration data acquisition system during turning operation. Analysis of the recorded signals in the FFT domain indicated significant reduction of chatter when a magnetic field is applied. It is apparent that a reduction of chatter amplitude will result in improved surface finish, tool life, machining accuracy, productivity, as well as reduction of operation.

Simulation and Experimental Research on Chatter Suppression Using Chaotic Spindle Speed Variation

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Kong Fansen ◽  
Liu Peng ◽  
Zhao Xingang
Keyword(s):  
Experimental Methods ◽  
Chaotic Signal ◽  
Spindle Speed ◽  
Speed Variation ◽  
Chatter Suppression ◽  
Spindle Speed Variation ◽  
Cutting Chatter ◽  
Chatter Control ◽  
Suppression Process ◽  
Chaotic Codes

A method for varying the spindle speed using chaotic signal to suppress chatter in machining is developed. The effects of spindle speed variation on cutting chatter control between using chaotic and sinusoidal signals were analyzed by simulation and experimental methods. Various chaotic codes are used in the chatter suppression process, and it is found that LORENZ-1 code results in the smallest machine noise.

Multi harmonic and random stiffness excitation for milling chatter suppression

2019 ◽  
Vol 120 ◽  
pp. 777-792 ◽  
Author(s):  
Chenxi Wang ◽  
Xingwu Zhang ◽  
Jinxin Liu ◽  
Ruqiang Yan ◽  
Hongrui Cao ◽  
...  
Keyword(s):  
Chatter Suppression ◽  
Milling Chatter

A computer model of human thermoregulation for a wide range of environmental conditions: the passive system

1999 ◽  
Vol 87 (5) ◽  
pp. 1957-1972 ◽  
Author(s):  
Dusan Fiala ◽  
Kevin J. Lomas ◽  
Martin Stohrer
Keyword(s):  
Numerical Procedure ◽  
Analytic Solutions ◽  
The Body ◽  
Activity Level ◽  
Passive System ◽  
Active System ◽  
Directional Radiation ◽  
Wide Range ◽  
Surface Convection ◽  
The Impact

A dynamic model predicting human thermal responses in cold, cool, neutral, warm, and hot environments is presented in a two-part study. This, the first paper, is concerned with aspects of the passive system: 1) modeling the human body, 2) modeling heat-transport mechanisms within the body and at its periphery, and 3) the numerical procedure. A paper in preparation will describe the active system and compare the model predictions with experimental data and the predictions by other models. Here, emphasis is given to a detailed modeling of the heat exchange with the environment: local variations of surface convection, directional radiation exchange, evaporation and moisture collection at the skin, and the nonuniformity of clothing ensembles. Other thermal effects are also modeled: the impact of activity level on work efficacy and the change of the effective radiant body area with posture. A stable and accurate hybrid numerical scheme was used to solve the set of differential equations. Predictions of the passive system model are compared with available analytic solutions for cylinders and spheres and show good agreement and stable numerical behavior even for large time steps.

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