Evaluation of plate drilling, process using vibration analysis

Dissertant

Nama, Sami Ali

Thesis advisor

Tawfiq, Muwaffaq Ali

University

University of Technology

Faculty

-

Department

Department of Electromechanical Engineering

University Country

Iraq

Degree

Ph.D.

Degree Date

2010

English Abstract

Drilling, is one of the most commonly used material removal processes in various industries, such as automotive, aircraft, aerospace, and others.

Vibration is at the heart of a variety of common problems in drilling holes.

Mathematical analysis is helping lu bring about a better understanding, of hole-making processes, including, how these vibrations behave, and what steps to take to bring therm under control, and to choose the optimized conditions with a range of vibration Frequencies.

This work is an experimental and analytical study for the evaluation of plate drilling process using vibration analysis.

In the experimental part of the study, a clamping arrangement was used to obtain the clamping condition Tur the plates of study; two opposite edges of the plate were clamped and the other two were free.

In the theoretical pan, an analytical Study for an isotropic, thin, rectangular plate was pei Formed to derive the governing equations for the forced vibration of all round simply supported plate with a concentrated load.

Four building blocks were considered to obtain the different clamping, methods.

Superposition method was used) to obtain the solution For the forced vibration of el amped-free-c lamped -free, simply supported-free-c lamped- free, and simply supported-free-simply supported-free plates.

This method was found to work extremely well, and fewer terms in the series were used to provide an equivalent accuracy of solutions.

The numerical part included the development of a computer program that takes in consideration the drilling conditions (speed, feed rate and diameter) and plate dimensions to calculate the plate dynamic response for the applied drilling force.

The drilling mechanism was analyzed by studying llie T/ariation nF the driLliJig force with time.

It was found that there were two regions at the beginning of the drilling operation which affects the total drilling, time, their contribution to the overall drilling time were found to vary between 9a/o to about 40%.

An empirical equation was derived from the experimental results to calculate the time of these two regions in terms of the drilling conditions.

The experimental force signals were analy^ed^ it was found chat these signals can be represented by Fourier series.

The terms of Fourier series were used in the computer program to calculate the plate dynamic response at a point near the plate free edge.

The results of the program were verified with ATSfSYS and a good agreement between the results was found5 where the difference was ranged from 1 % to 2.5%, This work deals with analyzing, the vibration in plates with, different dimensions and different clamping methods when they are drilled using different drilling conditions to obtain the optimisation of these conditions when vibration exists.

The effect of the drilling conditions on Fouri?r series terms- was considered and another empirical equation was derived to calculate the fundamental Fourier frequency at different drilling conditions.

It was found that the speed and feed have pronounced) effects on the Fourier series terms.

When the speed or feed increases, the amplitude and the fundamental frequency increase too while the time decreases.

It was also found that Fourier fundamental frequency is an effective parameter in determining, the maximum dimensions.

For the plate to be drilied within the resonance limit- This frequency depends on the plate thickness a_nd clamping method,, h increases with the increasing of the plate thickness and the number of clamped edges.

Finally^ it was found that the aspeel ratio has an important effect on the deflection amplitude and it depends on the plate damping method.

Main Subjects

Mechanical Engineering

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-305342