Tribology in Machine Design

205 Pages·1990·9.274 MB·English

by  Stolarski, T.A.

Tribology in Machine Design
T. A. STOLARSKI
MSc, PhD, DSc, DIG, CEng, MIMechE
1^1 U T T E R W O R T H
|g|E 1 N E M A N N
OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEW DELHI
Butterworth-Heinemann
Linacre House, Jordan Hill, Oxford OX2 8DP
225 Wildwood Avenue, Woburn, MA 01801-2041
A division of Reed Educational and Professional Publishing Ltd
6<^ A member of the Reed Elsevier pic group
First published 1990
Reprinted 2000
© T. A. Stolarski 1990
All rights reserved. No part of this publication may be reproduced in
any material form (including photocopying or storing in any medium by
electronic means and whether or not transiently or incidentally to some
other use of this publication) without the written permission of the
copyright holder except in accordance with the provisions of the Copyright,
Designs and Patents Act 1988 or under the terms of a licence issued by the
Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London,
England W1P OLP. Applications for the copyright holder's written
permission to reproduce any part of this publication should be addressed
to the publishers
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
Library of Congress Cataloguing in Publication Data
A catalogue record for this book is available from the Library of Congress
ISBN 0 7506 3623 8
Printed and bound in Great Britain
PLANT A
JTREE
FOR EVERY TITLE THAT WE PUBLISH, BUTTERWORTH-HEINEMANN
WILL PAY FOR BTCV TO PLANT AND CARE FOR A TREE.
Preface
The main purpose of this book is to promote a better appreciation of the
increasingly important role played by tribology at the design stage in
engineering. It shows how algorithms developed from the basic principles
of tribology can be used in a range of practical applications.
The book is planned as a comprehensive reference and source book that
will not only be useful to practising designers, researchers and postgraduate
students, but will also find an essential place in libraries catering for
engineering students on degree courses in universities and polytechnics. It is
rather surprising that, in most mechanical engineering courses, tribology -
or at least the application of tribology to machine design - is not a
compulsory subject. This may be regarded as a major cause of the time-lag
between the publication of new findings in tribology and their application
in industry. A further reason for this time-lag is the fact that too many
tribologists fail to present their results and ideas in terms of principles and
concepts that are directly accessible and appealing to the design engineer.
It is hoped that the procedures and techniques of analysis explained in
this book will be found helpful in applying the principles of tribology to the
design of the machine elements commonly found in mechanical devices and
systems. It is designed to supplement the Engineering Science Data Unit
(ESDU) series in tribology (well known to practising engineers), emphasiz-
ing the basic principles, giving the background and explaining the rationale
of the practical procedures that are recommended. On a number of
occasions the reader is referred to the appropriate ESDU item number, for
data characterizing a material or a tribological system, for more detailed
guidance in solving a particular problem or for an alternative method of
solution. The text advocates and demonstrates the use of the computer as a
design tool where long, laborious solution procedures are needed.
The material is grouped according to applications: elements of contact
mechanics, tribology of lower kinematic pairs, tribology of higher kine-
matic pairs, rolling contact bearings and surface damage of machine
elements. The concept of tribodesign is introduced in Chapter 1. Chapter 2
is devoted to a brief discussion of the basic principles of tribology, including
some new concepts and models of lubricated wear and friction under
complex kinematic conditions. Elements of contact mechanics, presented in
Chapter 3, are confined to the most technically important topics. Tribology
of lower kinematic pairs, sliding element bearings and higher kinematic
xii Preface
pairs are discussed in Chapters 4,5 and 6, respectively. Chapter 7 contains a
discussion of rolling contact bearings with particular emphasis on contact
problems, surface fatigue and lubrication techniques. Finally, Chapter 8
concentrates on lubrication and surface failures of involute gears.
At the end of Chapters 2-8 there is a list of books and selected papers
providing further reading on matters discussed in the particular chapter.
The choice of reference is rather personal and is not intended as a
comprehensive literature survey.
The book is based largely on the notes for a course of lectures on friction,
wear and lubrication application to machine design given to students in the
Department of Mechanical Engineering, Technical University of Gdansk
and in the Mechanical Engineering Department, Brunei University.
I would like to express my sincere appreciation to some of my former
colleagues from the Technical University of Gdansk where my own study of
tribology started. I owe a particular debt of gratitude to Dr B. J. Briscoe of
the Imperial College of Science and Technology, who helped me in many
different ways to continue my research in this subject. Finally, special
thanks are due to my wife Alicja for her patience and understanding during
the preparation of the manuscript.
Brunei University T.A.S.
Tribology in Machine Design
T. A. STOLARSKI
MSc, PhD, DSc, DIG, CEng, MIMechE
1^1 U T T E R W O R T H
|g|E 1 N E M A N N
OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEW DELHI
Butterworth-Heinemann
Linacre House, Jordan Hill, Oxford OX2 8DP
225 Wildwood Avenue, Woburn, MA 01801-2041
A division of Reed Educational and Professional Publishing Ltd
6<^ A member of the Reed Elsevier pic group
First published 1990
Reprinted 2000
© T. A. Stolarski 1990
All rights reserved. No part of this publication may be reproduced in
any material form (including photocopying or storing in any medium by
electronic means and whether or not transiently or incidentally to some
other use of this publication) without the written permission of the
copyright holder except in accordance with the provisions of the Copyright,
Designs and Patents Act 1988 or under the terms of a licence issued by the
Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London,
England W1P OLP. Applications for the copyright holder's written
permission to reproduce any part of this publication should be addressed
to the publishers
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
Library of Congress Cataloguing in Publication Data
A catalogue record for this book is available from the Library of Congress
ISBN 0 7506 3623 8
Printed and bound in Great Britain
PLANT A
JTREE
FOR EVERY TITLE THAT WE PUBLISH, BUTTERWORTH-HEINEMANN
WILL PAY FOR BTCV TO PLANT AND CARE FOR A TREE.
Preface
The main purpose of this book is to promote a better appreciation of the
increasingly important role played by tribology at the design stage in
engineering. It shows how algorithms developed from the basic principles
of tribology can be used in a range of practical applications.
The book is planned as a comprehensive reference and source book that
will not only be useful to practising designers, researchers and postgraduate
students, but will also find an essential place in libraries catering for
engineering students on degree courses in universities and polytechnics. It is
rather surprising that, in most mechanical engineering courses, tribology -
or at least the application of tribology to machine design - is not a
compulsory subject. This may be regarded as a major cause of the time-lag
between the publication of new findings in tribology and their application
in industry. A further reason for this time-lag is the fact that too many
tribologists fail to present their results and ideas in terms of principles and
concepts that are directly accessible and appealing to the design engineer.
It is hoped that the procedures and techniques of analysis explained in
this book will be found helpful in applying the principles of tribology to the
design of the machine elements commonly found in mechanical devices and
systems. It is designed to supplement the Engineering Science Data Unit
(ESDU) series in tribology (well known to practising engineers), emphasiz-
ing the basic principles, giving the background and explaining the rationale
of the practical procedures that are recommended. On a number of
occasions the reader is referred to the appropriate ESDU item number, for
data characterizing a material or a tribological system, for more detailed
guidance in solving a particular problem or for an alternative method of
solution. The text advocates and demonstrates the use of the computer as a
design tool where long, laborious solution procedures are needed.
The material is grouped according to applications: elements of contact
mechanics, tribology of lower kinematic pairs, tribology of higher kine-
matic pairs, rolling contact bearings and surface damage of machine
elements. The concept of tribodesign is introduced in Chapter 1. Chapter 2
is devoted to a brief discussion of the basic principles of tribology, including
some new concepts and models of lubricated wear and friction under
complex kinematic conditions. Elements of contact mechanics, presented in
Chapter 3, are confined to the most technically important topics. Tribology
of lower kinematic pairs, sliding element bearings and higher kinematic
xii Preface
pairs are discussed in Chapters 4,5 and 6, respectively. Chapter 7 contains a
discussion of rolling contact bearings with particular emphasis on contact
problems, surface fatigue and lubrication techniques. Finally, Chapter 8
concentrates on lubrication and surface failures of involute gears.
At the end of Chapters 2-8 there is a list of books and selected papers
providing further reading on matters discussed in the particular chapter.
The choice of reference is rather personal and is not intended as a
comprehensive literature survey.
The book is based largely on the notes for a course of lectures on friction,
wear and lubrication application to machine design given to students in the
Department of Mechanical Engineering, Technical University of Gdansk
and in the Mechanical Engineering Department, Brunei University.
I would like to express my sincere appreciation to some of my former
colleagues from the Technical University of Gdansk where my own study of
tribology started. I owe a particular debt of gratitude to Dr B. J. Briscoe of
the Imperial College of Science and Technology, who helped me in many
different ways to continue my research in this subject. Finally, special
thanks are due to my wife Alicja for her patience and understanding during
the preparation of the manuscript.
Brunei University T.A.S.
Contents

Preface ......................................................................................................................... xi
1. Introduction to the Concept of Tribodesign ...................................................... 1
1.1 Specific Principles of Tribodesign .......................................................................... 4
1.2 Tribological Problems in Machine Design .......................................................... 6
1.2.1 Plain Sliding Bearings ...................................................................................... 6
1.2.2 Rolling Contact Bearings ................................................................................ 7
1.2.3 Piston, Piston Rings and Cylinder Liners .................................................... 8
1.2.4 Cam and Cam Followers ................................................................................ 9
1.2.5 Friction Drives .................................................................................................. 10
1.2.6 Involute Gears ................................................................................................. 10
1.2.7 Hypoid Gears ........................................................................................................ 11
1.2.8 Worm Gears ......................................................................................................... 12
2. Basic Principles of Tribology ......................................................................... 13
2.1 Origins of Sliding Friction ....................................................................................... 13
2.2 Contact Between Bodies in Relative Motion ..................................................... 14
2.3 Friction Due to Adhesion ................................................................................... 15
2.4 Friction Due to Ploughing ...................................................................................... 16
2.5 Friction Due to Deformation .............................................................................. 17
2.6 Energy Dissipation During Friction ..................................................................... 18
2.7 Friction under Complex Motion Conditions ....................................................... 18
2.8 Types of Wear and Their Mechanisms .............................................................. 19
2.8.1 Adhesive Wear ..................................................................................................... 19
v
vi Contents
2.8.2 Abrasive Wear ................................................................................................. 20
2.8.3 Wear Due to Surface Fatigue ......................................................................... 21
2.8.4 Wear Due to Chemical Reactions ............................................................... 22
2.9 Sliding Contact Between Surface Asperities ...................................................... 23
2.10 The Probability of Surface Asperity Contact ...................................................... 26
2.11 Wear in Lubricated Contacts ............................................................................. 31
2.11.1 Rheological Lubrication Regime ..................................................................... 33
2.11.2 Functional Lubrication Regime .................................................................... 33
2.11.3 Fractional Film Defect ..................................................................................... 34
2.11.4 Load Sharing in Lubricated Contacts .............................................................. 37
2.11.5 Adhesive Wear Equation ................................................................................. 39
2.11.6 Fatigue Wear Equation ............................................................................... 40
2.11.7 Numerical Example ......................................................................................... 41
2.12 Relation Between Fracture Mechanics and Wear ............................................... 45
2.12.1 Estimation of Stress Intensity under Non-Uniform Applied Loads ................. 47
2.13 Film Lubrication ........................................................................................................... 48
2.13.1 Coefficient of Viscosity ......................................................................................... 48
2.13.2 Fluid Film in Simple Shear ................................................................................... 49
2.13.3 Viscous Flow Between Very Close Parallel Surfaces ....................................... 50
2.13.4 Shear Stress Variations Within the Film ......................................................... 51
2.13.5 Lubrication Theory by Osborne Reynolds ...................................................... 51
2.13.6 High-Speed Unloaded Journal ............................................................................ 53
2.13.7 Equilibrium Conditions in a Loaded Bearing .................................................. 53
2.13.8 Loaded High-Speed Journal ................................................................................ 54
2.13.9 Equilibrium Equations for Loaded High-Speed Journal ................................... 57
2.13.10 Reaction Torque Acting on the Bearing .......................................................... 59
2.13.11 The Virtual Coefficient of Friction ........................................................................ 59
2.13.12 The Sommerfeld Diagram ................................................................................... 60
References ............................................................................................................................................... 63
3. Elements of Contact Mechanics ......................................................................... 64
3.1 Introduction ............................................................................................................. 64