The Experts below are selected from a list of 1941 Experts worldwide ranked by ideXlab platform
Jenq-shyong Chen - One of the best experts on this subject based on the ideXlab platform.
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Centrifugal force induced dynamics of a motorized high-Speed Spindle
The International Journal of Advanced Manufacturing Technology, 2006Co-Authors: Jenq-shyong Chen, Yii-wen HwangAbstract:Trend of the high-Speed and high efficiency machining has pushed the continuous demand of higher Spindle Speed and power for the machining center application. Because the extremely high Speed produces significant centrifugal force, it creates a need to predict the Spindle dynamical characteristics at dynamic states. This work presents analysis results of the Spindle dynamic of a motorized high Speed Spindle with angular ball contact bearings. For a machining center, two major subsystems determining the overall Spindle stiffness are the shaft/bearing subsystem and the draw bar mechanism subsystem. Shaft/bearing stiffness as well as the natural frequency decreased at high Speeds due to the bearing softening and gyroscopic effect. The bearing softening is the major reason of the reduced Spindle stiffness, while the gyroscopic effect plays the secondary effect. Angular contact ball bearing softening at high Speed is due to the reduced contact load and increased contact angle at the ball/inner-raceway contact interface caused by the centrifugal force. For the draw bar mechanism, analysis results show that the dynamic draw force at high Speeds is significantly increased from that designed at the static state. Because the toolholder/Spindle interface stiffness is proportional to the draw force, centrifugal force theoretically contributes a plus to the Spindle stiffness at dynamic state. The dynamic draw force, however, is dependent on the friction loss inside the draw bar mechanism. Because of the low friction coefficient, the ball-type mechanism is superior to the wedge type mechanism.
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bearing load analysis and control of a motorized high Speed Spindle
International Journal of Machine Tools & Manufacture, 2005Co-Authors: Jenq-shyong Chen, Kwan Wen ChenAbstract:Angular contact ball bearings are the most popular bearing type used in the high Speed Spindle for machining centers. Because the bearing load is increased rapidly with the raised Spindle Speed due to the centrifugal force and temperature raise, proper initial preload and especially operating-induced load control of the angular ball bearing is important to the rigidity, accuracy and life of the Spindle. The bearing layout, preload mechanism an on-line load bearing control are discussed in this paper. The management of the centrifugal force and thermally-induced bearing loads is especially emphasized. An active bearing load monitoring and control mechanism that consists of an integrated strain-gage load cells and piezoelectric actuators has been developed and tested. This active control and monitoring mechanism on-line adjusts the bearing load according the cutting conditions. Experiments were conducted to identify the proper initial bearing preload range. Optimal preload for the lowest bearing temperature raise existed for a specified Spindle Speed. The optimum preload, however, should be raised when the operational Speed is increased.
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Bearing load analysis and control of a motorized high Speed Spindle
International Journal of Machine Tools and Manufacture, 2005Co-Authors: Jenq-shyong Chen, Kwan Wen ChenAbstract:Angular contact ball bearings are the most popular bearing type used in the high Speed Spindle for machining centers. Because the bearing load is increased rapidly with the raised Spindle Speed due to the centrifugal force and temperature raise, proper initial preload and especially operating-induced load control of the angular ball bearing is important to the rigidity, accuracy and life of the Spindle. The bearing layout, preload mechanism an on-line load bearing control are discussed in this paper. The management of the centrifugal force and thermally-induced bearing loads is especially emphasized. An active bearing load monitoring and control mechanism that consists of an integrated strain-gage load cells and piezoelectric actuators has been developed and tested. This active control and monitoring mechanism on-line adjusts the bearing load according the cutting conditions. Experiments were conducted to identify the proper initial bearing preload range. Optimal preload for the lowest bearing temperature raise existed for a specified Spindle Speed. The optimum preload, however, should be raised when the operational Speed is increased. ?? 2005 Elsevier Ltd. All rights reserved.
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characterizations and models for the thermal growth of a motorized high Speed Spindle
International Journal of Machine Tools & Manufacture, 2003Co-Authors: Jenq-shyong ChenAbstract:Abstract In this paper, the characterizing and modeling of the thermal growth of a motorized high Speed Spindle is reported. A motorized high Speed Spindle has more complicated dynamic, non-stationary and Speed-dependent thermal characteristics than conventional Spindles. The centrifugal force and thermal expansion occurring on the bearings and motor rotor change the thermal characteristics of the built-in motor, bearings and assembly joints. It was found that conventional static models using regression analysis and artificial neural network failed to give satisfactory model accuracy and robustness. An auto-regression dynamic thermal error model, that considers the temperature history and Spindle-Speed information, has been proposed and proved to improve the model accuracy. However, it was found that temperature-based thermal error models, that correlated thermal displacement of the rotating cutting tool to the temperature measurements on the Spindle housing, were not robust. Many nonlinear and time-varying thermal sources, such as coolant jacket, motor air gap, motion joints and assembly interfaces influence thermal displacement. The relationship between temperature measurements and thermal displacements is highly nonlinear, time-varying and non-stationary. A new thermal model which correlates the Spindle thermal growth to thermal displacements measured at some locations of the rotating Spindle shaft has been proposed. It was found that the displacement-based thermal error model has much better accuracy and robustness than the temperature-based model.
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Characterizations and models for the thermal growth of a motorized high Speed Spindle
International Journal of Machine Tools and Manufacture, 2003Co-Authors: Jenq-shyong Chen, Wei-yao HsuAbstract:In this paper, the characterizing and modeling of the thermal growth of a motorized high Speed Spindle is reported. A motorized high Speed Spindle has more complicated dynamic, non-stationary and Speed-dependent thermal characteristics than conventional Spindles. The centrifugal force and thermal expansion occurring on the bearings and motor rotor change the thermal characteristics of the built-in motor, bearings and assembly joints. It was found that conventional static models using regression analysis and artificial neural network failed to give satisfactory model accuracy and robustness. An auto-regression dynamic thermal error model, that considers the temperature history and Spindle-Speed information, has been proposed and proved to improve the model accuracy. However, it was found that temperature-based thermal error models, that correlated thermal displacement of the rotating cutting tool to the temperature measurements on the Spindle housing, were not robust. Many nonlinear and time-varying thermal sources, such as coolant jacket, motor air gap, motion joints and assembly interfaces influence thermal displacement. The relationship between temperature measurements and thermal displacements is highly nonlinear, time-varying and non-stationary. A new thermal model which correlates the Spindle thermal growth to thermal displacements measured at some locations of the rotating Spindle shaft has been proposed. It was found that the displacement-based thermal error model has much better accuracy and robustness than the temperature-based model. ?? 2003 Elsevier Ltd. All rights reserved.
Jin H. Huang - One of the best experts on this subject based on the ideXlab platform.
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Analyzing characteristics of high-Speed Spindle bearing under constant preload
Proceedings of the Institution of Mechanical Engineers Part J: Journal of Engineering Tribology, 2017Co-Authors: Van The Than, Chi-chang Wang, Jin H. HuangAbstract:Bearings play an important role in a high-Speed Spindle. Its characteristics are often influenced by Speed and thermal effects. This paper presents an approach that combines an inverse method with ...
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Estimating time-varying heat sources in a high Speed Spindle based on two measurement temperatures
International Journal of Thermal Sciences, 2017Co-Authors: Van The Than, Thi Thao Ngo, Cheng Chi Wang, Jin H. HuangAbstract:Combined the finite element model and the conjugate gradient method, this article presents an inverse method to estimate time-varying heat sources in a high Speed Spindle based on experimental temperatures of housing surface. An experimental setup and process to measure temperatures for inversely predicting heat generation sources in high Speed Spindle and validating inverse results are developed. Two measured temperatures are used to estimate two unknown heat generation sources for constant and time-varying Spindle Speeds. Two other measured temperatures are utilized to validate the inverse results. Results show that the estimated temperatures correlate well with the measured data, and also that the heat generation prediction is satisfactory. In addition, temperatures from the proposed inverse method are consistent with measured temperatures at the verification points. It can be concluded that the proposed inverse method is a promising method for determining heat sources in the heat transfer of complicated structures with different materials.
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Nonlinear thermal effects on high-Speed Spindle bearings subjected to preload
Tribology International, 2016Co-Authors: Van The Than, Jin H. HuangAbstract:This paper presents a unified method to predict nonlinear thermal characteristics of a high-Speed Spindle bearing subjected to a preload. Based on a quasi-static model and finite different method, the change of thermal contact resistance, bearing parameters, and heat source with temperature per second is completely analyzed using a new algorithm. The bearing parameters and lubricant viscosity affected by time-varying temperature are updated in each time step. As a result, the thermal effects on contact angles, contact forces, the preload, and stiffness of the bearing are found. Moreover, our analysis results show that the estimated preload and bearing stiffness nonlinearly vary with the increase in temperature and the present method takes much less computational effort than the finite element method.
Choon Man Lee - One of the best experts on this subject based on the ideXlab platform.
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A study on the thermal characteristics and experiments of High-Speed Spindle for machine tools
International Journal of Precision Engineering and Manufacturing, 2015Co-Authors: Jian Lee, Dong Hyeon Kim, Choon Man LeeAbstract:Based on the finite element method and thermal analysis, a study on the thermal characteristics and experiments of a 40,000 rpm high-Speed Spindle for machine tools are carried out. In this study, finite element analysis for the Spindle system is carried out to obtain the temperature distribution, temperature rise and thermal deformation of the Spindle system as affected by different rotation Speeds. And then through vibration test, the relationship between thermal deformation and vibration during rotation of the Spindle was tested and analyzed. By comparing the calculated results with experimental results, the accuracy of the model was verified. This provides the basis for design of the high Speed Spindle system.
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Static and dynamic analysis and optimization design of 40,000-rpm high-Speed Spindle for machine tools
Transactions of the Korean Society of Mechanical Engineers A, 2013Co-Authors: Dong Hyeon Kim, Choon Man Lee, H.j. ChoiAbstract:The Spindle is the main component in machine tools. The static and dynamic characteristics of the Spindle directly affect the machining accuracy of workpieces. The characteristics of the Spindle depend on the shaft size, bearing span, built-in motor location, and so on. Therefore, the appropriate selection of these parameters is important to improve the Spindle characteristics. This paper presents the analysis of the static and dynamic characteristics and optimization design of a 40,000-rpm high-Speed Spindle. Statistical analysis for optimization and finite element analysis were performed. This study uses the response surface method to optimize the objective function and design factors. The targets are the natural frequency and displacement. The design factors are the shaft length, shaft diameter, bearing span, and motor location. The optimized design provides better results than the initial model, and these results are expected to improve the static and dynamic characteristics of the Spindle. © 2013 The Korean Society of Mechanical Engineers.
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A study determining the optimal machining conditions for a 40,000rpm ultra high Speed Spindle system
Precision Engineering, 2012Co-Authors: Seong Jin Park, Dong Hyeon Kim, Choon Man LeeAbstract:This report describes an investigation for deriving optimum machining conditions for a milling process using a 40,000 rpm (DmN 2.4 million) ultra-high-Speed Spindle system. A two-step design of experiments is proposed to obtain the optimum machining conditions. A two-level fractional factorial design method is used to obtain some factors that affect the machining conditions in the Spindle system. Then, a central composite circumscribed method, which is one of the response surface methods, is used to obtain optimal machining conditions for the Spindle. Several finished milling experiments are carried out by varying the rotational Speed, feed rate, depth of cut, interval of lubricating oil application, air pressure, and so on. The surface roughness, cutting force, and cutting temperature are measured, and the effects of the machining conditions are analyzed using a regression analysis method. Based on the experimental results and regression analyses, optimal machining conditions and estimation equations are obtained to improve the machinability in milling processes with the Spindle. ©
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A new simulation technique for rotational balance of a high-Speed Spindle using design of experiment
WMSCI 2006 - The 10th World Multi-Conference on Systemics Cybernetics and Informatics Jointly with the 12th International Conference on Information Sy, 2006Co-Authors: W.j. Chung, Y D Cho, Choon Man Lee, S.h. Yoon, Wen Chin LeeAbstract:High Speed over 10,000 rpm for the Spindle of machine tools has been a hot issue because of a strong demand of high productivity. The rotating accuracy of a high-Speed Spindle depends on the centrifugal force which can be affected by an unbalance mass. Consequently, rotational balance problem becomes more important in high-Speed Spindles. This paper has developed a new simulation technique using flexible body analysis based on ANSYS® and ADAMS®. The proposed technique aims at figuring out the longitudinal distance of an unbalancing mass on a Spindle, based on mass-addition approach and DOE (Design Of Experiment). The analysis of rotational unbalancing factors including unbalance masses and z-direction distance, the radius of a Spindle, and added masses, is performed using DOE. The proposed simulation technique has been shown to be effective through a target model operating at 20,000 rpm.
Bo Yang - One of the best experts on this subject based on the ideXlab platform.
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thermal structure interaction characteristics of a high Speed Spindle bearing system
International Journal of Machine Tools & Manufacture, 2019Co-Authors: Shilong Wang, Sibao Wang, Bo YangAbstract:Abstract The neglection of thermal-structure interaction of high-Speed Spindle system may lead to the modeling error of the thermal characteristics. To improve the modeling accuracy, the thermal-structure interaction mechanism was analyzed and the closed-loop iterative modeling method of thermal characteristics was proposed to modify the heat sources and thermal boundary conditions of the Spindle system in each substep. The heat generation of bearings and built-in motor, the convective coefficients and the thermal contact resistances (TCRs) of bearing joints were computed. The heat generation of bearings was calculated by the SKF bearing thermal model and the results were compared with that obtained by integral method. The heat generation of bearings was modified by considering the combined effect of the lubricant viscosity variation and thermally-induced preload of bearings. Moreover, a novel geometrical-mechanical-thermal model for TCRs was proposed by characterizing the rough surface morphology and by establishing the multi-scale contact mechanics of joint surfaces. To validate the effectiveness of the proposed method, the thermal characteristic experiments of the Spindle system were conducted under different rotational Speeds. The results showed that the modeling errors in the temperature field and thermal deformation are reduced significantly and that this model has the ability of thermal error compensation.
Wei-yao Hsu - One of the best experts on this subject based on the ideXlab platform.
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Characterizations and models for the thermal growth of a motorized high Speed Spindle
International Journal of Machine Tools and Manufacture, 2003Co-Authors: Jenq-shyong Chen, Wei-yao HsuAbstract:In this paper, the characterizing and modeling of the thermal growth of a motorized high Speed Spindle is reported. A motorized high Speed Spindle has more complicated dynamic, non-stationary and Speed-dependent thermal characteristics than conventional Spindles. The centrifugal force and thermal expansion occurring on the bearings and motor rotor change the thermal characteristics of the built-in motor, bearings and assembly joints. It was found that conventional static models using regression analysis and artificial neural network failed to give satisfactory model accuracy and robustness. An auto-regression dynamic thermal error model, that considers the temperature history and Spindle-Speed information, has been proposed and proved to improve the model accuracy. However, it was found that temperature-based thermal error models, that correlated thermal displacement of the rotating cutting tool to the temperature measurements on the Spindle housing, were not robust. Many nonlinear and time-varying thermal sources, such as coolant jacket, motor air gap, motion joints and assembly interfaces influence thermal displacement. The relationship between temperature measurements and thermal displacements is highly nonlinear, time-varying and non-stationary. A new thermal model which correlates the Spindle thermal growth to thermal displacements measured at some locations of the rotating Spindle shaft has been proposed. It was found that the displacement-based thermal error model has much better accuracy and robustness than the temperature-based model. ?? 2003 Elsevier Ltd. All rights reserved.
