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machine-tools
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Pattern analysis by active learning method classifier
, Article Journal of Intelligent and Fuzzy Systems ; Vol. 26, issue. 1 , 2014 , p. 49-62 ; Shouraki, S. B ; Afrakoti, I. E. P ; Sharif University of Technology
Abstract
Active Learning Method (ALM) is a powerful fuzzy soft computing tool, developed originally in order to promote an engineering realization of human brain. This algorithm, as a macro-level brain imitation, has been inspired by some behavioral specifications of human brain and active learning ability. ALM is an adaptive recursive fuzzy learning algorithm, in which a complex Multi Input, Multi Output system can be represented as a fuzzy combination of several Single-Input, Single-Output systems. SISO systems as associative layer of algorithm capture partial spatial knowledge of sample data space, and enable a granular knowledge resolution tuning mechanism through the learning process. The...
Design Optimization of a Ladder Secondary Single-Sided Linear Induction Motor for Improved Performance
, Article IEEE Transactions on Energy Conversion ; Volume 30, Issue 4 , 2015 , Pages 1595-1603 ; 08858969 (ISSN) ; Nasiri Gheidari, Z ; Sharif University of Technology
Abstract
In this paper, design and optimization of a ladder-type single-sided linear induction motor (Ladder SLIM) for machine tool applications is investigated. High-speed linear induction machines suffer from the end-effect phenomenon, which can reduce the thrust and result in declined output characteristics. Although it is common to consider this phenomenon in high-speed applications, it is essential to take it into account in the design and analysis of low-speed low-air-gap linear machines. In addition, Ladder SLIMs have significant flux density ripples, and using skewed bars for secondary of the machine is a common solution for it. Therefore, providing required equations, an algorithm for...
Study of the effects of miniaturization on static and dynamic form errors in desktop milling machines
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings, 13 November 2009 through 19 November 2009 ; Volume 4 , 2010 , Pages 587-595 ; 9780791843772 (ISBN) ; Movahhedy, M. R ; Akbari, J ; Sharif University of Technology
Abstract
Desktop and miniaturized machine tools are a new trend in small scale and customized manufacturing. The performance of these machines in terms of their energy consumption, machining fluid consumption and their precision have been investigated in the literature, but the effect of miniaturization on static deflection, stability against chatter and the resulting surface error has not been studied. In this paper, the performance of the desktop milling machine tool in terms of their static and dynamic form errors is studied. The performance of a miniature milling machine used for end milling of a typical workpiece is compared with a similar machine of conventional size through dimensional...
Dynamic stability of a Hexaglide machine tool for milling processes
, Article International Journal of Advanced Manufacturing Technology ; Volume 86, Issue 5-8 , 2016 , Pages 1753-1762 ; 02683768 (ISSN) ; Movahhedy, M. R ; Zohoor, H ; Alasty, A ; Sharif University of Technology
Springer-Verlag London Ltd
Abstract
One of the major issues related to parallel kinematic machine tools (PKMs) is their structural dependency on their configuration. In this paper, the machine configuration effect on its stability is investigated for the case of a Hexaglide machine tool. An FEM model of the Hexaglide machine tool is developed. The frequency response function (FRF) at the tool tip is obtained by a modal analysis. The numerical results are validated through comparison with those of an experimental modal test. The pose dependency of the PKM stability over its workspace is investigated. It is shown that the machine stability over the workspace is dependent on the spindle/tool/holder system characteristic. For...
Multi-objective selection and structural optimization of the gantry in a gantry machine tool for improving static, dynamic, and weight and cost performance
, Article Concurrent Engineering Research and Applications ; Volume 24, Issue 1 , 2016 , Pages 83-93 ; 1063293X (ISSN) ; Dabbagh, V ; Amini, H ; Sarhan, A. A. D ; Akbari, J ; Hamdi, M ; Ong, Z. C ; Sharif University of Technology
SAGE Publications Ltd
Abstract
In this investigation, the multi-objective selection and optimization of a gantry machine tool is achieved by analytic hierarchy process, multi-objective genetic algorithm, and Pareto-Edgeworth-Grierson-multi-criteria decision-making method. The objectives include maximum static deformation, the first four natural frequencies, mass, and fabrication cost of the gantry. Further structural optimization of the best configuration was accomplished using multi-objective genetic algorithm to improve all objectives except cost. The result of sensitivity analysis reveals the major contribution of columns of gantry with respect to the crossbeam's contribution. After determining the most effective...
Configuration design in scalable reconfigurable manufacturing systems (RMS); a case of single-product flow line (SPFL)
, Article International Journal of Production Research ; 2017 , Pages 1-23 ; 00207543 (ISSN) ; Houshmand, M ; Fatahi Valilai, O ; Sharif University of Technology
Abstract
The dynamic nature of today’s manufacturing industry, which is caused by the intense global competition and constant technological advancements, requires systems that are highly adaptive and responsive to demand fluctuations. Reconfigurable manufacturing systems (RMS) enable such responsiveness through their main characteristics. This paper addresses the problem of RMS configuration design, where the demand of a single product varies throughout its production life cycle, and the system configuration must change accordingly to satisfy the required demand with minimum cost. A two-phased method is developed to handle the primary system configuration design and the necessary system...
Design and manufacturing of ultrasonic motor with in-plane and out-of-plane bending vibration modes of rectangular plate with large contact area
, Article Measurement: Journal of the International Measurement Confederation ; Volume 109 , 2017 , Pages 425-431 ; 02632241 (ISSN) ; Sarhan, A. A. D ; Akbari, J ; Mardi, N. A ; Sharif University of Technology
Abstract
Ultrasonic motor working with coupled in-plane and out-of-plane vibration modes of rectangular plate is proposed and experimentally investigated. Thanks to its unique configuration, proposed motor provides large contact area between stator and rotor of motor which can reduce wear and enhance motor life-time. The proposed motor is designed using finite element method and according to the design, a prototype is fabricated and its working characteristics such as speed, normal and driving force and working frequency are measured. Overall dimension of designed prototype is 49 × 14 × 2 mm, working frequency of motor is 49.6 kHz, no-load speed and stall force of motor are 122 rpm and 0.32 mN m at...
Study of Chatter Stability in Boring Using Operating Deflection Shape
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
Chatter in machining systems is a limiting factor of workpiece surface, tool and machine life and material removal rate. Because of this, studying and modeling of vibrations is very important in the machining. This study is much importer in the boring operation because boring bar's length to diameter ratio is very high and so it is very sensitive to vibrations. As we know, vibration characteristics of a machine change between its operating condition and its resting mode. Because of this it's better to study machine's vibrations when it's working. This study requires some methods that can find operating parameters of machine. The aim of this work is to find these parameters. For finding these...
Study of the Effect of Miniaturization of Milling Machines on the Quality of
the Product Surface
,
M.Sc. Thesis
Sharif University of Technology
;
Akbari, Javad
(Supervisor)
;
Movahhedy, Mohammad Reza
(Supervisor)
Abstract
Improvements in the technology of manufacturing mechanical parts in recent years, has enabled the manufacturers to produce machine tools in small sizes (installable on a desk) which look like conventional counterparts and are called desk-top size machine tools. One important aspect of machine tools operation is the machined surface integrity. Thus, it is necessary to compare desk-top size machines with their conventional counterparts from this point of view. This comparison is the purpose of this thesis in which “surface error” and “surface roughness” of milling machines as a kind of machine tools are compared between conventional and miniaturized machines. To compare the surface errors,...
Numerical analysis of metal cutting with chamfered and blunt tools
, Article Journal of Manufacturing Science and Engineering ; Volume 124, Issue 2 , 2002 , Pages 178-188 ; 10871357 (ISSN) ; Altintas, Y ; Gadala, M. S ; Sharif University of Technology
American Society of Mechanical Engineers(ASME)
2002
Abstract
In high speed machining of hard materials, tools with chamfered edge and materials resistant to diffusion wear are commonly used. In this paper, the influence of cutting edge geometry on the chip removal process is studied through numerical simulation of cutting with sharp, chamfered or blunt edges and with carbide and CBN tools. The analysis is based on the use of ALE finite element method for continuous chip formation process. Simulations include cutting with tools of different chamfer angles and cutting speeds. The study shows that a region of trapped material zone is formed under the chamfer and acts as the effective cutting edge of the tool, in accordance with experimental observations....
Prediction of spindle dynamics in milling by sub-structure coupling
, Article International Journal of Machine Tools and Manufacture ; Volume 46, Issue 3-4 , 2006 , Pages 243-251 ; 08906955 (ISSN) ; Gerami, J. M ; Sharif University of Technology
2006
Abstract
The Stability of machining process depends on the dynamics of the machine tool, among other things. However, the dynamics of the machine tool changes when the tool is changed. To avoid the need for repeating the measurements, sub-structuring analysis may be used to couple the tool and spindle frequency response functions. A major difficulty in this approach is the determination of joint stiffness and damping between the two sub-structures. In particular, the measurement of rotational responses (RDOFs) at joints is a difficult task. In this research, a simple joint model that accounts for RDOFs is proposed. It is shown that this model avoids RDOF measurement while taking into account the...
Prediction of chatter in high speed milling including gyroscopic effects
, Article International Journal of Machine Tools and Manufacture ; Volume 46, Issue 9 , 2006 , Pages 996-1001 ; 08906955 (ISSN) ; Mosaddegh, P ; Sharif University of Technology
2006
Abstract
Dynamic stability of machine tools during operations is dependent on many parameters including the spindle speed. In high and ultra high speed machining, the gyroscopic effect on the spindle dynamics becomes more pronounced and can affect the borders of stability of the rotating system. In this paper, a finite element based model of spindle, tool holder and cutting tool is presented which uses Timoshenko beam theory to obtain the frequency response of the system when gyroscopic terms are included. Using this response, the stability of a high speed spindle system in the presence of gyroscopic effect is investigated. It is shown that the gyroscopic effects lower the critical depth of cut in...
Penetration-elimination method for five-axis CNC machining of sculptured surfaces
, Article International Journal of Machine Tools and Manufacture ; Volume 47, Issue 10 , 2007 , Pages 1625-1635 ; 08906955 (ISSN) ; Akbari, J ; Vafaeesefat, A ; Sharif University of Technology
2007
Abstract
In this paper, a new tool positioning strategy for five-axis machining, called the penetration-elimination method (PEM), is introduced. The PEM gains from two innovative techniques that can considerably improve the computational efficiency during the calculation of the optimal tool orientations. The first technique includes developing a quantitative definition for the gouging concept and using this definition in conjunction with powerful numerical root-finder algorithms to determine the optimized tool orientations. The second technique dynamically detects the ineffective grid points and drops them from calculations and consequently takes a great role in reducing the computational burden. The...
Leaching recovery of zinc, cobalt and manganese from zinc purification residue
, Article International Journal of Engineering, Transactions B: Applications ; Volume 20, Issue 2 , 2007 , Pages 133-140 ; 1728-144X (ISSN) ; Darvishi, D ; Mos'hefi Shabestari, Z ; Keshavarz Alamdari, E ; Sadrnezhaad, S. K ; Sharif University of Technology
Materials and Energy Research Center
2007
Abstract
This paper reports on the recovery of zinc, cobalt and manganese by two-step leaching of zinc-plants purification residue with sulfuric acid. The residue, hot filter press cake (HFC), contains 14 % ZnO, 4.8 % Co 3O4 and 22.9 % MnO. Effects of different parameters are determined and used to optimize the process. With acid to hot filter press cake (HFC) stoichiometry of 0.85, acid concentration of 30 g/L and temperature of 25°C, it took two minutes to separate zinc from zinc plant residue. Hydrogen peroxide (H2O2) was used as an oxidation agent. The most suitable acid concentration for leaching of both cobalt and manganese was 50 g/L. Recovery of cobalt and manganese increased with peroxide...
Reliability improvement of industrial drives using multi-objective optimization
, Article 2008 IEEE Industry Applications Society Annual Meeting, IAS'08, Edmonton, AB, 5 October 2008 through 9 October 2008 ; 2008 ; 01972618 (ISSN); 9781424422791 (ISBN) ; Zolghadri, M. R ; Khaligh, A ; Sharif University of Technology
2008
Abstract
In a motor-drive system, there are many factors which can be considered as a figure of merit in drive control algorithm. All of these factors should be evaluated simultaneously to achieve the reliable performance of drive. In this paper, an optimization problem is constructed on a direct torque controlled induction motor drive using a candidate from different parts of drive system: inverter loss from section of solid state converter, motor loss from section of electromechanical converter and torque ripple from mechanical section. Minimization of this cost function leads to the optimum values of drive control parameters. © 2008 IEEE
Simulation of chatter vibrations in reaming
, Article ASME International Mechanical Engineering Congress and Exposition, IMECE 2007, Seattle, WA, 11 November 2007 through 15 November 2007 ; Volume 3 , 2008 , Pages 441-447 ; 0791842975 (ISBN); 9780791842973 (ISBN) ; Movahhedy, M. R ; Sharif University of Technology
2008
Abstract
A time domain approach is used to study the cutting conditions in reaming process that leads the system to regenerative chatter vibrations. The dynamic analysis of the system includes inertia of the tool, centripetal and Coriolis terms, damping and the first mode bending of reamer. A model of cutting forces proportional to chip cross sectional area and process damping proportional to cutting speed is considered. Numerical simulation based on the Euler integration scheme is carried out to obtain time domain solution of the equation. Despite linearization in force modelling, the model is nonlinear due to the change in the tool engagement area. Another nonlinearity included in the model jumping...
Steganalysis of LSB based image steganography using spatial and frequency domain features
, Article 2009 IEEE International Conference on Multimedia and Expo, ICME 2009, New York, NY, 28 June 2009 through 3 July 2009 ; 2009 , Pages 1744-1747 ; 9781424442911 (ISBN) ; Ghaemmaghami, S ; Sharif University of Technology
2009
Abstract
In this paper, we propose a method for steganalysis of grayscale images using both spatial and Gabor features. The basis of our work is to use Gabor filter coefficients and statistics of the graylevel co-occurrence matrix of images to train a support vector machine. We show that this feature set works well in steganalysis of grayscale images steganographied by LSB matching and S-tools. ©2009 IEEE
Calibration of parallel kinematic machine tools using mobility constraint on the tool center point
, Article International Journal of Advanced Manufacturing Technology ; Volume 45, Issue 5-6 , 2009 , Pages 531-539 ; 02683768 (ISSN) ; Pendar, H ; Alasty, A ; Vossoughi, G. R ; Sharif University of Technology
2009
Abstract
In the application of parallel kinematic machine tools (PKM), because of errors in the geometric parameters, it is necessary to calibrate the PKM to improve the positioning accuracy. In existing self-calibration methods, either some redundant sensors on passive joints or some mobility constraints on the kinematic chains are used. However, the mobility constraints imposed on kinematic chains might apply large forces during the test on legs and passive joints. Also, these kinds of calibrating are applicable only on PKMs in which their actuated joints can be used as passive joints. To overcome weaknesses of existing methods, a novel approach to calibration based on imposing position constraints...
Kinematics and singularity analysis of the hexaglide parallel robot
, Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 11 , 2009 , Pages 37-43 ; 9780791848722 (ISBN) ; Pendar, H ; Alasty, A ; Vossoughi, G. R ; Sharif University of Technology
2009
Abstract
In the past few years, parallel manipulators have become increasingly popular in industry, especially, in the field of machine tools. Hexaglide is a 6 DOF parallel manipulator that can be used as a high speed milling machine. In this paper, the kinematics and singularity of Hexaglide parallel manipulator are studied systematically. At first, this robot has been modeled and its inverse and forward kinematic problems have been solved. Then, formulas for solving inverse velocity are derived and Jacobian matrix is obtained. After that, three different types of singularity for this type of robot have been investigated. Finally a numerical example is presented. Copyright © 2008 by ASME
Development of inverse receptance coupling method for prediction of milling dynamics
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 5 , 2010 , Pages 339-346 ; 9780791849194 (ISBN) ; Movahhedy, M. R ; Ahmadian, M. T ; Moradi, H ; Sharif University of Technology
2010
Abstract
Receptance coupling substructure analysis (RCSA) is extensively used to determine the dynamic response of milling tool at its tip for the purpose of prediction of machining stability. A major challenge in using this approach is the proper modelling of the joint between the substructures and determination of its parameters. In this paper, an inverse RCSA is developed for experimental extraction of tool-holder frequency response function (FRF) including joint parameters. The accuracy and efficiency of this method is evaluated through an analytical investigation. It is shown that the extracted holder FRF can provide a highly accurate prediction of the tool tip FRF. The developed method is used...