Loading...
Search for:
angular-contact-ball-bearing
0.01 seconds
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...
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...
Thermo-elastic Development of Cylindrical and Spherical Superelements and Introduce a New Gigh Speed Angular Contact Bearing Superelement Model
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
Angular contact bearings are utilized in many industrial types of machinery, including machine tools’ spindle. Spindle is one of the most important parts of a machine tool, which has a substantial impact on dynamic properties and stability of machining processes. Spindles’ motion takes place under guidance of bearings, which are mainly angular contact type. Since bearings’ loading under forces that are resulted from angular velocity and temperature increment are intensified, it is required to control the applied forces in operating situation, in order to predict the hardness, accuracy, efficiency, and life time of spindle. Thus, determining the dynamic performance of machine tool’s spindle,...
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...
An investigation of contact angles in angular contact ball bearings accounting for high speed effects and preload
, Article SAE International Journal of Passenger Cars - Mechanical Systems ; Volume 2, Issue 1 , 2009 , Pages 780-790 ; 19463995 (ISSN) ; Zahedi, A ; Sharif University of Technology
Abstract
Angular contact ball bearings are the most commonly used types of bearings. Although simple in appearance, these bearings have a complicated and nonlinear behavior, and have significant effect on the dynamics of a rotating system. Accounting for high speed effects adds to the complexity of their behavior. The governing equations of the bearing amount to the solution of a set of nonlinear equations for each rolling element at each iteration, which represents a tedious and expensive solution. In this work, a simplified model for angular contact ball bearings under the action of arbitrary loading including high speed effects and preload is presented. The model considers five degrees of freedom...
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...