طراحي و ساخت دستگاه پرداختكاري سايشي لوله ها به كمك ميدان مغناطيسي و تحليل آماري عوامل موثر بر فرايند

چكيده انگليسي :

Design and Manufacturing of Magnetic Abrasive Finishing Apparatus and Statistical Analysis of Effective Parameters Mehrdad Givi m givi@me iut ac ir Date of Submission 19 April 2010 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Dr Alireza Fadaei Tehrani mcjaft@cc iut ac ir Abstract Development of high tech industries such as nuclear aerospace and medical instrument manufacturing during recent century requires to super finished surfaces without any defect Therefore it is necessary to work on modern and effective methods of machining and finishing Magnetic Abrasive finishing MAF is a magnetic assisted method applying for polishing of the inner and external surfaces of tubes as well as flat surfaces When magnetic abrasive powders locate along the magnetic flux lines a flexible magnetic abrasive brush FMAB will form on the surface as the abrasive tool and make pressure in order to penetrate to the surface If the magnetic field or the working surface starts moving relative to other one material removal takes place in the form of micro nano chips resulting in nano finishing This polishing method does not have limitations of the traditional methods such as lapping or honing that produce micro cracks and other surface defects and can not be used for finishing of complex surfaces It will be possible to easily achieve surface roughness around Ra 0 1 m and less using magnetic abrasive finishing process The present thesis includes three significant subdivisions Firstly several experiments have been done in order to check the feasibility of production of rotational magnetic field applicable for MAF process by mean of the stators of electric motors In these tests some three phase stators have been studied and it is revealed that the rotational magnetic field produced by means of AC current can not form a dense and uniform abrasive brush that is necessary for polishing operation Secondly a magnetic abrasive finishing apparatus has been designed and manufactured for internal polishing of tubes This apparatus has an innovative design allows the permanent poles to simultaneously have a rotational and axial vibrating movement The finishing unit is mounted on the support of a lathe turning machine and is able to internally finish a specific length of internal surface of tubes It is easy to vary or control the effective parameters such as working gap rotational speed and the frequency of axial vibration of the poles that can affect on finishing performance This unique apparatus has distinguished characteristics compared to previous designs After preliminary tests DOE methods are applied in order to do some planned experiments The goal has been the investigation and founding the effective parameters on outputs such as surface roughness and material removal amount The experiments performed on aluminum tubes examine the effects of weight of the abrasive powders mesh size of the powders number of process cycles and frequency of axial vibration on the finishing characteristics Main effects of the parameters and their interactions have been obtained based on response surface method Statistical analysis of data ANOVA has been done using MINITAB software demonstrates that all of the parameters and their squares except square of frequency value have a significant influence on ultimate surface roughness Furthermore all of the factors except frequency and the square of the weight and number of cycles significantly affect the material removal amount The interactions effects are relatively negligible Regression equation showing the relation between inputs and outputs of the MAF process is also found Scanning Electron Microscopy SEM Atomic Force Microscopy AFM images adaptively confirm the result about surface roughness improvement after MAF Key Words Abrasive Finishing Magnetic Field Surface Roughness DOE ANOVA

گيوي، مهرداد

طراحي و ساخت دستگاه پرداختكاري سايشي لوله ها به كمك ميدان مغناطيسي و تحليل آماري عوامل موثر بر فرايند

زبري سطح , طراحي آزمايشات , آناليز واريانس