A New Approach to the Early Prediction of Turning Chatter

1994 ◽  
Vol 116 (4) ◽  
pp. 485-488 ◽  
Author(s):  
Shan-Fei Bao ◽  
Wen-Guo Zhang ◽  
Jun-Yi Yu ◽  
Si-Mao Qiao ◽  
Fu-Lun Yang
Keyword(s):  
Theoretical Analysis ◽  
Cutting Force ◽  
Frequency Difference ◽  
Early Prediction ◽  
New Approach ◽  
Dynamic Cutting Force

A new approach to the early prediction of turning chatter is described in this paper; the interval frequency difference H in the amplitude domain of the dynamic cutting force is taken as a prediction parameter. The theoretical analysis and experiments results indicate that the approach presented can lead to a quick prediction of turning chatter with higher accuracy and adaptability.

Modeling of residual stresses by correlating surface topography in machining of AISI 52100 steel

2021 ◽  
pp. 1-26
Author(s):  
Chao Liu ◽  
Yan He ◽  
Yufeng Li ◽  
Yulin Wang ◽  
Shilong Wang ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Cutting Force ◽  
Surface Topography ◽  
Analytical Model ◽  
Analytical Models ◽  
Workpiece Surface ◽  
Dynamic Cutting Force ◽  
Intermittent Cutting ◽  
Effect Of Surface

Abstract The residual stresses could affect the ability of components to bear loading conditions and also the performance. The researchers considered workpiece surface as a plane and ignored the effect of surface topography induced by the intermittent cutting process when modeling residual stresses. The aim of this research develops an analytical model to predict workpiece residual stresses during intermittent machining by correlating the effect of surface topography. The relative motions of tool and workpiece are analyzed for modeling thermal-mechanical and surface topography. The influence of dynamic cutting force and thermal on different positions of surface topography is also considered in analytical model. Then the residual stresses model with the surface topography effect can be developed in intermittent cutting. The analytical models of dynamic cutting force, surface topography and residual stresses are verified by the experiments. The variation trend of evaluated values of the residual stress of workpiece is basically consistent with that of measured values. The compressive residual stress of workpiece surface in highest point of the surface topography are higher than that in the lowest point.

Analysis of the effect of tool posture on stability considering the nonlinear dynamic cutting force coefficient

2021 ◽  
pp. 1-19
Author(s):  
Zepeng Li ◽  
Rong Yan ◽  
Xiaowei Tang ◽  
Fang Yu Peng ◽  
Shihao Xin ◽  
...  
Keyword(s):  
Cutting Force ◽  
Nonlinear Dynamic ◽  
Chip Thickness ◽  
Cutting Depth ◽  
Force Coefficient ◽  
Critical Cutting Depth ◽  
Dynamic Cutting Force ◽  
Cutting Force Coefficient ◽  
Tool Posture ◽  
Instantaneous Uncut Chip Thickness

Abstract In aviation and navigation, complicated parts are milled with high-speed low-feed-per-tooth milling to decrease tool vibration for high quality. Because the nonlinearity of the cutting force coefficient (CFC) is more evident with the relatively smaller instantaneous uncut chip thickness, the stable critical cutting depth and its distribution against different tool postures are affected. Considering the nonlinearity, a nonlinear dynamic CFC model that reveals the effect of the dynamic instantaneous uncut chip thickness on the dynamic cutting force is derived based on the Taylor expansion. A five-axis bull-nose end milling dynamics model is established with the nonlinear dynamic CFC model. The stable critical cutting depth distribution with respect to tool posture is analyzed. The stability results predicted with the dynamic CFC model are compared with those from the static CFC model and the constant CFC model. The effects of tool posture and feed per tooth on stable critical cutting depth were also analyzed, and the proposed model was validated by cutting experiments. The maximal stable critical cutting depths that can be achieved under different tool postures by feed per tooth adjustment were calculated, and corresponding distribution diagrams are proposed for milling parameter optimization.

Simulation and Research of Dynamic Voltage Detection and Regulator Based on MATLAB

2014 ◽  
Vol 536-537 ◽  
pp. 1527-1531
Author(s):  
Ya Feng Li ◽  
Zi Wei Zheng
Keyword(s):  
Theoretical Analysis ◽  
Reactive Power ◽  
Voltage Regulator ◽  
New Approach ◽  
Dynamic Voltage ◽  
Harmonic Voltage ◽  
Simulation Results ◽  
Harmonic Source ◽  
Detecting Method ◽  
Dynamic Voltage Regulator

The Series Dynamic Voltage Regulator can compensate the harmonics distortion caused by voltage type harmonic source This paper presents a new approach of detecting harmonic voltage in dq0 coordinates, based on the generalized instantaneous reactive power ,and used in the series dynamic voltage regulator successfully. It is demonstrated by theoretical analysis and simulation results that the proposed detecting method of harmonic voltage is correct and valid.

scholarly journals Philosophical Education toward Democratization and Boko Haram Insurgency in Nigeria

2016 ◽  
Vol 9 (9) ◽  
pp. 87
Author(s):  
Felix Okechukwu Ugwuozor
Keyword(s):  
Theoretical Analysis ◽  
Civic Culture ◽  
Boko Haram ◽  
Policy Makers ◽  
New Approach ◽  
Civic Society ◽  
Philosophical Education ◽  
Educational Framework ◽  
Future Policy ◽  
Beliefs And Attitudes

<p class="apa">This paper examines Nigeria's democratization dilemmas and the imperatives of an educational framework against the backdrop of the Boko Haram insurgency. It identifies and connects the pattern, character and dynamics of the existing educational system. It also discusses the system’s failure in calling for a new approach to overcome the prevailing dearth of civic order and the increasing spread of dissent groups. This new method is about acculturating Nigerian youth into a more civic culture, a Nigeria where citizens can live side by side with each other in peace.” While examining both theoretical and practical characteristics of this new educational agenda, the paper especially examines the link between philosophical education and the development of a civic culture, trusting that such a connection suggests an approach to education that may assist future policy makers, educators, and teachers. Specific theoretical analysis of pedagogical and philosophical education contained here can further the current understanding of how philosophical education is likely to facilitate the development of the values, beliefs, and attitudes that generally underpin the operations of a civic society, developments desperately needed to address the problem of Boko Haram and the increasing spread of dissent groups in Nigeria.</p>

Improved dynamic cutting force modelling in micro milling of metal matrix composites part II: Experimental validation and prediction

2019 ◽  
Vol 234 (8) ◽  
pp. 1500-1515
Author(s):  
Zhichao Niu ◽  
Kai Cheng
Keyword(s):  
Cutting Force ◽  
Metal Matrix Composites ◽  
Cutting Forces ◽  
Metal Matrix ◽  
Micro Milling ◽  
Force Model ◽  
Matrix Composites ◽  
Cutting Force Model ◽  
Side Milling ◽  
Dynamic Cutting Force

The effects of cutting dynamics and the particles' size and density cannot be ignored in micro milling of metal matrix composites. This article presents the improved dynamic cutting force modelling for micro milling of metal matrix composites based on the previous analytical model. This comprehensive improved cutting force model, taking the influence of the tool run-out, actual chip thickness and resultant tool tip trajectory into account, is evaluated and validated through well-designed machining trials. A series of side milling experiments using straight flutes polycrystalline diamond end mills are carried out on the metal matrix composite workpiece under various cutting conditions. Subsequently, the measured cutting forces are compensated by a Kalman filter to achieve the accurate cutting forces. These are further compared with the predicted cutting forces to validate the proposed dynamic cutting force model. The experimental results indicate that the predicted and measured cutting forces in micro milling of metal matrix composites are in good agreement.

Dynamic cutting force prediction for micro end milling considering tool vibrations and run-out

2018 ◽  
Vol 233 (7) ◽  
pp. 2248-2261 ◽  
Author(s):  
Xuewei Zhang ◽  
Tianbiao Yu ◽  
Wanshan Wang
Keyword(s):  
Cutting Force ◽  
Cutting Forces ◽  
End Milling ◽  
Chip Thickness ◽  
Milling Process ◽  
Force Model ◽  
Dynamic Cutting Force ◽  
Micro End Milling ◽  
Tool Vibrations ◽  
End Milling Process

An accurate prediction of cutting forces in the micro end milling, which is affected by many factors, is the basis for increasing the machining productivity and selecting optimal cutting parameters. This paper develops a dynamic cutting force model in the micro end milling taking into account tool vibrations and run-out. The influence of tool run-out is integrated with the trochoidal trajectory of tooth and the size effect of cutting edge radius into the static undeformed chip thickness. Meanwhile, the real-time tool vibrations are obtained from differential motion equations with the measured modal parameters, in which the process damping effect is superposed as feedback on the undeformed chip thickness. The proposed dynamic cutting force model has been experimentally validated in the micro end milling process of the Al6061 workpiece. The tool run-out parameters and cutting forces coefficients can be identified on the basis of the measured cutting forces. Compared with the traditional model without tool vibrations and run-out, the predicted and measured cutting forces in the micro end milling process show closer agreement when considering tool vibrations and run-out.

What Can We Make of Unsubstantiated Child Abuse Reports? A New Approach

2017 ◽  
Vol 13 (2) ◽  
Author(s):  
Michael Malcolm
Keyword(s):  
Time Series ◽  
Child Abuse ◽  
Theoretical Analysis ◽  
General Public ◽  
Child Outcomes ◽  
Empirical Approach ◽  
Previous Literature ◽  
New Approach ◽  
Data Generating Process ◽  
Statistical Time

AbstractOnly about a quarter of child abuse reports are ultimately substantiated, which has caused some concern among policymakers and the general public. But previous literature suggests that unsubstantiated and substantiated reports may not be much different from each other in terms of child outcomes. We present a Bayesian theoretical analysis of the data-generating process underlying maltreatment substantiation, and then take a new empirical approach by examining the statistical time-series relationship between substantiated and unsubstantiated reports. We show that the two series are cointegrated. This suggests that unsubstantiated reports are not mostly malicious or unfounded, but that they emanate from the same signals as verifiable, substantiated abuse.

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