Loading...
Search for:
machine-tools
0.007 seconds
Total 39 records
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,...
Configuration design in scalable reconfigurable manufacturing systems (RMS); a case of single-product flow line (SPFL)
, Article International Journal of Production Research ; Volume 56, Issue 11 , 2018 , Pages 3932-3954 ; 00207543 (ISSN) ; Houshmand, M ; Fatahi Valilai, O ; Sharif University of Technology
Taylor and Francis Ltd
2018
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...
Configuration design of scalable reconfigurable manufacturing systems for part family
, Article International Journal of Production Research ; 2019 ; 00207543 (ISSN) ; Houshmand, M ; Saitou, K ; Fatahi Valilai, O ; Sharif University of Technology
Taylor and Francis Ltd
2019
Abstract
Intense global competition, dynamic product variations, and rapid technological developments force manufacturing systems to adapt and respond quickly to various changes in the market. Such responsiveness could be achieved through new paradigms such as Reconfigurable manufacturing systems (RMS). In this paper, the problem of configuration design for a scalable reconfigurable RMS that produces different products of a part family is addressed. In order to handle demand fluctuations of products throughout their lifecycles with minimum cost, RMS configurations must change as well. Two different approaches are developed for addressing the system configuration design in different periods. Both...
Configuration design of scalable reconfigurable manufacturing systems for part family
, Article International Journal of Production Research ; 2019 ; 00207543 (ISSN) ; Houshmand, M ; Saitou, K ; Fatahi Valilai, O ; Sharif University of Technology
Taylor and Francis Ltd
2019
Abstract
Intense global competition, dynamic product variations, and rapid technological developments force manufacturing systems to adapt and respond quickly to various changes in the market. Such responsiveness could be achieved through new paradigms such as Reconfigurable manufacturing systems (RMS). In this paper, the problem of configuration design for a scalable reconfigurable RMS that produces different products of a part family is addressed. In order to handle demand fluctuations of products throughout their lifecycles with minimum cost, RMS configurations must change as well. Two different approaches are developed for addressing the system configuration design in different periods. Both...
Configuration design of scalable reconfigurable manufacturing systems for part family
, Article International Journal of Production Research ; Volume 58, Issue 10 , 2020 , Pages 2974-2996 ; Houshmand, M ; Saitou, K ; Fatahi Valilai, O ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
Intense global competition, dynamic product variations, and rapid technological developments force manufacturing systems to adapt and respond quickly to various changes in the market. Such responsiveness could be achieved through new paradigms such as Reconfigurable manufacturing systems (RMS). In this paper, the problem of configuration design for a scalable reconfigurable RMS that produces different products of a part family is addressed. In order to handle demand fluctuations of products throughout their lifecycles with minimum cost, RMS configurations must change as well. Two different approaches are developed for addressing the system configuration design in different periods. Both...
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...
An integrated analysis of productivity, hole quality and cost estimation of single-pulse laser drilling process
, Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; Volume 235, Issue 14 , 2021 , Pages 2273-2287 ; 09544054 (ISSN) ; Shehab, E ; Salonitis, K ; Suder, W ; Niamat, M ; Jamil, M ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
Laser drilling is a well-established manufacturing process utilised to produce holes in various aeroengine components. This research presents an experimental investigation on the effects of laser drilling process parameters on productivity (material removal rate), hole quality (hole taper) and drilling cost. Single-pulse drilling was employed to drill a thin-walled Inconel 718 superalloy plate of 1 mm thickness using pulsed Nd:YAG laser. The experiments were designed using Box-Behnken statistical approach to investigate the impacts of pulse energy, pulse duration, gas pressure and gas flow rate on the selected responses. Multi-objective optimisation was performed using response surface...
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...
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...
Minimization of Non-repeatable Runout (NRRO) in High-Speed Spindle Bearings
, Article SAE 2021 Automotive Technical Papers, WONLYAUTO 2021, 1 January 2021 ; Issue 2021 , 2021 ; 01487191 (ISSN) ; Khodaygan, S ; Sharif University of Technology
SAE International
2021
Abstract
The production with high quality at the lowest production time can be a key means to success in the competitive environment of manufacturing companies. Therefore, in recent years, the need for extra precise and high-speed machine tools has been impressively increased in manufacturing applications. One of the main sources of errors in the motion of 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 waviness 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 of high-speed...
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...
Using a combination of vibration absorber and a classical active controller to suppress the chatter vibration and increase the stability in turning process
, Article 10th International Conference on Modern Circuits and Systems Technologies, MOCAST 2021, 5 July 2021 through 7 July 2021 ; 2021 ; 9781665418478 (ISBN) ; Moradi, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
Free, forced, and self-excited vibrations are the three main types of machine tool vibrations. Self-excited vibration is the most important type of destructive vibration in machining. The most important factor in increasing the chipping rate, stability, and tool life is decreasing this type of destructive vibration. In this paper, we aim to introduce a method to control the self-excited vibrations by the means of the combining a vibration absorber as a passive controlling method and a classical active controller such as PID or compensator or the other classical methods. Utilizing the SIMULINK toolbox of MATLAB software, first, we designed and added the vibration absorber to the model...
Numerical simulation of interaction of mode-coupling and regenerative chatter in machining
, Article Journal of Manufacturing Processes ; Volume 27 , 2017 , Pages 252-260 ; 15266125 (ISSN) ; Movahhedy, M. R ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
Chatter vibration is a major obstacle in achieving high performance machining. In order to present a realistic model of chatter vibration, in this research, a finite element simulation of orthogonal chip formation combined with a 2D model of machine tool dynamics is developed. The proposed approach has the ability to incorporate various, mostly nonlinear, phenomena affecting chatter occurrence. The dynamic allows the tool to vibrate as a result of chip load variation leading to chatter. The 2DOF model makes it possible to observe the occurrence of model coupling phenomenon, in addition to the regeneration of waviness mechanism. The investigation of mode-coupling and regeneration phenomena in...
3D numerical investigation of the coupled interaction behavior between mechanized twin tunnels and groundwater – A case study: Shiraz metro line 2
, Article Tunnelling and Underground Space Technology ; Volume 103 , 2020 ; Hataf, N ; Pirastehfar, K ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Mechanized tunneling method using Tunnel Boring Machine (TBM) is being extensively employed in urban areas, especially when excavation takes place underneath the groundwater table. In this study, three-dimensional coupled Finite Element Analyses (FEA) have been performed to investigate the interaction mechanism between mechanized twin tunnels construction of Shiraz metro (line 2) and groundwater. Firstly, two soil constitutive models (Mohr-Coulomb and Modified Cam-Clay model) of Shiraz lean clay are validated against drained triaxial compression test data. Varying the permeability of the grout layer within the specified range, the base numerical model is then calibrated by the field data of...
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...
Design and experimental evaluation of a precise and compact tubular ultrasonic motor driven by a single-phase source
, Article Precision Engineering ; Volume 48 , 2017 , Pages 172-180 ; 01416359 (ISSN) ; Sarhan, A. A. D ; Akbari, J ; Azizi Mardi, N ; Sharif University of Technology
Elsevier Inc
2017
Abstract
A precise and compact tubular ultrasonic motor driven by a single-phase source is proposed and tested in this study. The motor is designed by modeling a motor stator in FEM software. The motor fabricated according to the design is tested experimentally and its working characteristics including speed and torque are measured and presented. The maximum speed and torque of the motor are 59 rpm and 0.28 mN m at 80 Vpp of applied voltage. The proposed motor possesses advantages such as a simple and compact structure with application in the fields of robotics, space, medical devices and high-resolution stages, among others. The proposed motor is a good candidate for applications where accurate...
Design and analysis of an elliptical-shaped linear ultrasonic motor
, Article Sensors and Actuators, A: Physical ; Volume 278 , 2018 , Pages 67-77 ; 09244247 (ISSN) ; Akbari, J ; Sharif University of Technology
Elsevier B.V
2018
Abstract
A linear ultrasonic motor (LUSM) with an elliptical-shaped metallic stator and two orthogonal vibration modes is presented in this research. The driving tip's desired vibration is generated by the excitation of two piezoelectric actuators installed inside the stator by two sinusoidal voltages with ±[Formula presented] phase difference. The working principle of the motor is described and mathematically formulated. Furthermore, finite element analysis and parametric optimization are performed to finalize the motor design. A prototype of the motor is fabricated and evaluated by identification and operation tests. The experimental and numerical characteristic curves of the motor are presented...
Extending the inverse receptance coupling method for prediction of tool-holder joint dynamics in milling
, Article Journal of Manufacturing Processes ; Volume 14, Issue 3 , 2012 , Pages 199-207 ; 15266125 (ISSN) ; Movahhedy, M. R ; Moradi, H ; Ahmadian, M. T ; Sharif University of Technology
Elsevier
2012
Abstract
Recently, receptance coupling substructure analysis (RCSA) is used for stability prediction of machine tools through its dynamic response determination. A major challenge is the proper modelling of the substructures joints and determination of their parameters. In this paper, a new approach for predicting tool tip FRF is presented. First, inverse RCSA formulation is extended so that the holder FRFs can be identified directly through experimental modal tests. The great advantage of this formulation is its implementation in arbitrary point numbers along joint length. Therefore, in comparison with previous inverse RCSA approaches, a more realistic joint model can be considered. In addition, due...
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....