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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...
Design and Manufacture of Variable Preload System for High-Speed Spindle Bearings
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
Machine tool spindles of late require high stiffness and fast rotation characteristics all at once for high- speed, high-efficient processing, as well as for a wide range of use rotation. Bearing preload is the main reason for Dynamic characteristics of spindle. As such, many studies are being carried out on automatic variable preload control methods that apply a preload to a spindle bearing as an alternative to the existing fixed position preload and constant pressure preload methods. This study introduces a newly design automatic variable preload system. This system can automatically reduced preload with increasing spindle rotational speed through the use of centrifugal force. The system...
Design and Fabricating of a High Speed Micro Spindle
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor) ; Akbari, Javad (Supervisor)
Abstract
According to development of industry in every field such as nanotechnology and micro electro mechanical system (MEM) fabricating of high speed machining with micro dimension has been expanded. Micro spindles are such a device which is useful in many industries such as air space and electronic field. These machines can work in high speed and production rate with vast variety of features. Their dimensions are in millimeter range. So they can manufacture miniature features. Fabricating and technical science production of a high speed micro spindle with speed of more than 100000 RPM (micro macro milling) is purpose of this project. After to literature review according to science of micro...
Design, Manufacturing and Control of High Speed Spindle Resistant to Speed Fluctuations and Sudden Mass Unbalance
, M.Sc. Thesis Sharif University of Technology ; Durali, Mohammad (Supervisor)
Abstract
Industrial rotating parts experiencing high angular velocities must be examined for structural integrity and strength before being installed in an operating machine. This includes performing non-destructive tests such as rotating at high speeds that generate near yield stresses in part critical points. The dangers associated with performing such tests require that these tests be performed in devices named “Spin Testers”. In this device the test is normally carried out in vacuum and within armored walls. A critical component of the spin tester is the spindle to which the rotating part is attached. Besides carrying weight of the test piece and rotating at high speeds, the spindle must be...
Thermo-mechanical Modeling of Angular Contact Ball-Bearings in High Speed Machine Tool Spindles
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
Machining in its general concept forms the major part of manufacturing processes regarding time and cost. Therefore any progress in machining techniques would be well beneficial. High speed machining is one of the recent concepts in machining technology which has attracted much attention and effort. But high speed spindles as the main part of high speed machines, have been notorious for their lack of reliability and sudden failure which originates mostly from thermal problems. In order to ensure reliable operation of spindles it is necessary to predict thermo-mechanical behavior of machine-tool spindles. The major sources of heat in a spindle are angular contact ball bearings (the most...
Design and manufacturing of High Speed Milling Spindle
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor) ; Akbari, Javad (Supervisor)
Abstract
High speed machining is becoming a progressive trend in machining processes. The main part of a high speed machine tool is its spindle. The purpose of this thesis is to design and manufcture a high speed spindle for milling machine that can rotate at speed of 16000 rpm. This spindle can be used as a test bed for experimental parametric study on the effects of spindle design parameters on the performance of spindle bearings. Various components of the spindle is studied and designed. High speed angular contact bearings and roller bearings are used in the spindle to provide high precision as well as good thermal performance. The spindle is built and tested for high precision machining with...
A speed-dependent variable preload system for high speed spindles
, Article Precision Engineering ; Volume 40 , April , 2015 , Pages 182-188 ; 01416359 (ISSN) ; Movahhedy, M. R ; Sharif University of Technology
Elsevier Inc
2015
Abstract
High speed machine tools are required to operate in a wide range of spindle rotational speeds with high stiffness and high accuracy. The stiffness of the spindle is largely dependent on the axial preload of the angular contact bearings. A large preload is required at lower range of speeds to provide sufficient stiffness for vibration-free heavy cutting. However, at higher speeds, it results in rapid temperature rise and reduces the life of the bearing. For optimum performance, it is essential that the bearing preload is reduced as the rotational speed increases. In this paper, an automatic variable preload system is proposed that changes the preload on the bearings as a function of...
Thermo-mechanical modeling of high speed spindles
, Article Scientia Iranica ; Volume 19, Issue 2 , 2012 , Pages 282-293 ; 10263098 (ISSN) ; Movahhedy, M. R ; Sharif University of Technology
2012
Abstract
Prediction of the thermo-mechanical behavior of machine-tool spindles is essential in the reliable operation of high speed machine tools. In particular, the performance of these high speed spindles is dependent on their thermal behavior. The main source of heat generation in the spindle is the friction torque in angular contact ball bearings. This paper presents an effort to develop a comprehensive model of high speed spindles that includes viable models for the mechanical and thermal behavior of its major components, i.e., bearings, shaft and housing. Spindle housing and shaft are treated as six-degree-of-freedom Timoshenko beam elements. Bearings are modeled as two-node elements with five...