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dimensional-tolerance
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Tolerance analysis of mechanical assemblies based on fuzzy - Small degrees of freedom (F-SDOF) model
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 12 November 2010 through 18 November 2010 ; Volume 3, Issue PARTS A AND B , 2010 , Pages 519-524 ; 9780791844274 (ISBN) ; Movahhedy, M. R ; Sharif University of Technology
Abstract
Tolerances naturally generate an uncertain environment for design and manufacturing. In this paper, a novel fuzzy based tolerance representation approach for modeling the variations of geometric features due to dimensional tolerances is presented. The two concepts of fuzzy theory and small degrees of freedom are combined to introduce the fuzzy-small degrees of freedom model (F-SDOF). This model is suitable for tolerance analysis of mechanical assemblies with linear and angular tolerances. The presented method is compatible with the current dimensioning and tolerancing standards. The application of the proposed methodology is illustrated through presenting an example problem
Parametric Tolerance Analysis of Rigid Assemblies
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
In a mechanical system, dimensional and geometrical tolerances of components propagate kinematically through assembly and accumulate in a way that alters the critical dimensions of the assembly. Analysis of the accumulation of components tolerances and their influences on the critical dimensions of the assembly (design requirements) and also understanding the behavior of the entire system according to these effects is called tolerance analysis. Tolerance analysis is a key tool in quality improvement, cost reduction and profit growth, and it plays an important role in industrial productions. The Majority of mechanical systems are 3-Dimentional in nature, and approximating them as...
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...
Optimal Design of Tolerances in the Non-rigid Assemblies under the Thermal Impact
, M.Sc. Thesis Sharif University of Technology ; Khodaygan, Saeed (Supervisor)
Abstract
Tolerance allocation in the recent mechanical assembly is significant because it straightly affects product performance and cost. Loose tolerances may cause the quality defect while tight tolerances can increase the cost. Thermal effects and the temperature gradients are one of the factors that caused changes in the size and geometry of the components during the performance of mechanical assemblies. This thesis proposes a new approach for tolerance design considering the thermal effects, to achieve lower manufacturing cost and good product quality. Finite element analysis is used to determine the deformation of components in an assembly. The neural network is trained using experimental...
Fuzzy-small degrees of freedom representation of linear and angular variations in mechanical assemblies for tolerance analysis and allocation
, Article Mechanism and Machine Theory ; Volume 46, Issue 4 , April , 2011 , Pages 558-573 ; 0094114X (ISSN) ; Movahhedy, M. R ; Foumani, M. S ; Sharif University of Technology
2011
Abstract
Tolerances naturally generate an uncertain environment for design and manufacturing. In this paper, a novel fuzzy based tolerance representation approach for modeling the variations of geometric features due to dimensional tolerances is presented. The two concepts of fuzzy theory and small degrees of freedom are combined to introduce the fuzzy-small degrees of freedom model (F-SDOF). This model is suitable for tolerance analysis of mechanical assemblies with linear and angular tolerances. Based on the fuzzy concept, a new index (called the assemblability index) is introduced which signifies the fitting quality of parts in the assembly. Graphical and numerical representations of tolerance...
Tolerance analysis of mechanical assemblies based on modal interval and small degrees of freedom (MI-SDOF) concepts
, Article International Journal of Advanced Manufacturing Technology ; Volume 50, Issue 9-12 , 2010 , Pages 1041-1061 ; 02683768 (ISSN) ; Movahhedy, M. R ; Saadat Fomani, M ; Sharif University of Technology
Abstract
Tolerance analysis is a key analytical tool for estimation of accumulating effects of the individual part tolerances on the design specifications of a mechanical assembly. This paper presents a new feature-based approach to tolerance analysis for mechanical assemblies with geometrical and dimensional tolerances. In this approach, geometrical and dimensional tolerances are expressed by small degrees of freedom (SDOF) of geometric entities (faces, feature axes, edges, and features of size) that are described by tolerance zones. The uncertainty of dimensions and geometrical form of features due to tolerances is mathematically described using modal interval arithmetic. The two concepts of modal...