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Optimal Design of the High Speed Spindle Bearings to Reduce Non Repeatable Run Out
, M.Sc. Thesis Sharif University of Technology ; Khodaygan, Saeed (Supervisor) ; Movahhedy, Mohammad Reza (Co-Advisor)
Abstract
Creating synchronous conditions of precision and speed in rotating systems is a requirement for the design of these systems. The requirement to create these conditions is essential in various applications, such as machine tools and computer equipment. One of the main sources of error in the motion of the high speed spindles is the occurrence of non-repetitive runouts. The presence of non-repetitive runouts at high speeds greatly affects the accuracy of the rotating motion of rotating systems and reducing its effects is always considered in the design of high speed rotary systems. Usually, one of the most important factors in the occurrence of non-repetitive runouts is related to spindle...
Designing and Implementation of a Web-Based Cyber-Physical System for a CNC Milling Machine
, Ph.D. Dissertation Sharif University of Technology ; Akbari, Javad (Supervisor) ; Ghorbani, Mohammad (Co-Supervisor)
Abstract
In this work, a virtualized ball-end milling model is presented in Unity game engine environment, in which the machining process is simulated by proposing a new geometric approach. The model calculates and illustrates cutter-workpiece engagement area and cutting forces in a real-time manner. To calculate cutter-workpiece engagement, the workpiece’s top surface is considered a set of nodes. Then, using a new geometric method, the engagement area is calculated at any node on the engaging surface. Utilizing the calculated engagement area and adopting mechanistic force model, the cutting forces applied from each node on the workpiece surface to the tool’s cutting edge are calculated. The cutting...
Optimal design of the high-speed spindle bearings to minimize the non-repeatable runout
, Article SAE World Congress Experience, WCX 2019, 9 April 2019 through 11 April 2019 ; Volume 2019-April, Issue April , 2019 ; 01487191 (ISSN) ; Farahani, M. R ; Sharif University of Technology
SAE International
2019
Abstract
The production with high-quality at the lowest production time can be a key means to success in the competitive environment of the manufacturing companies. Therefore, in recent years, the need for the extra precise and high-speed machine tools has been impressively increased in the manufacturing applications. One of the main sources of errors in the motion of the high-speed spindles is the occurrence of non-repetitive runouts (NRRO) in the bearing. The NRRO can be caused by some factors such as the form of balls, the waveness of rings, the number of balls, and the permutation of one or two balls in the ball bearing. In this paper, a Taguchi-based approach is proposed for the optimal design...
Sensor runout compensation in active magnetic bearings via an integral adaptive observer
, Article Control Engineering Practice ; Volume 48 , 2016 , Pages 111-118 ; 09670661 (ISSN) ; Habibollahi, A ; Behzad, M ; Salarieh, H ; Mehdigholi, H ; Sharif University of Technology
Elsevier Ltd
Abstract
Sensor runout is one of the main sources of harmonic disturbances in active magnetic bearing systems. This type of the disturbance not only causes harmonic vibrations in the system but also changes the steady-state position of the axis of rotation from the geometric center of the AMB. In this paper, an integral adaptive observer is proposed to identify the dc and harmonic content of the sensor runout and to estimate the states of the system at the same time. The Lyapunov method is used to prove asymptotic stability of the proposed observer. Unlike the proportional observer which amplifies the measurement error, the sensor runout can be completely compensated when the states of the integral...
Harmonic disturbance attenuation in a three-pole active magnetic bearing test rig using a modified notch filter
, Article JVC/Journal of Vibration and Control ; Volume 23, Issue 5 , 2017 , Pages 770-781 ; 10775463 (ISSN) ; Behzad, M ; Salarieh, H ; Mehdigholi, H ; Sharif University of Technology
Abstract
This study is concerned with the problem of harmonic disturbance rejection in active magnetic bearing systems. A modified notch filter is presented to identify both constant and harmonic disturbances caused by sensor runout and mass unbalance. The proposed method can attenuate harmonic displacement and currents at the synchronous frequency and its integer multiples. The reduction of stability is a common problem in adaptive techniques because they alter the original closed-loop system. The main advantage of the proposed method is that it is possible to determine the stability margins of the system by few parameters. The negative phase shift of the modified notch filter can be tuned to...