DOCSLIB.ORG

Contact Mechanics in Gears a Computer-Aided Approach for Analyzing Contacts in Spur and Helical Gears Master’S Thesis in Product Development

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Contact Mechanics in Gears a Computer-Aided Approach for Analyzing Contacts in Spur and Helical Gears Master’S Thesis in Product Development Two Contact Mechanics in Gears A Computer-Aided Approach for Analyzing Contacts in Spur and Helical Gears Master’s Thesis in Product Development MARCUS SLOGÉN Department of Product and Production Development Division of Product Development CHALMERS UNIVERSITY OF TECHNOLOGY Gothenburg, Sweden, 2013 MASTER’S THESIS IN PRODUCT DEVELOPMENT Contact Mechanics in Gears A Computer-Aided Approach for Analyzing Contacts in Spur and Helical Gears Marcus Slogén Department of Product and Production Development Division of Product Development CHALMERS UNIVERSITY OF TECHNOLOGY Göteborg, Sweden 2013 Contact Mechanics in Gear A Computer-Aided Approach for Analyzing Contacts in Spur and Helical Gears MARCUS SLOGÉN © MARCUS SLOGÉN 2013 Department of Product and Production Development Division of Product Development Chalmers University of Technology SE-412 96 Göteborg Sweden Telephone: + 46 (0)31-772 1000 Cover: The picture on the cover page shows the contact stress distribution over a crowned spur gear tooth. Department of Product and Production Development Göteborg, Sweden 2013 Contact Mechanics in Gears A Computer-Aided Approach for Analyzing Contacts in Spur and Helical Gears Master’s Thesis in Product Development MARCUS SLOGÉN Department of Product and Production Development Division of Product Development Chalmers University of Technology ABSTRACT Computer Aided Engineering, CAE, is becoming more and more vital in today's product development. By using reliable and efficient computer based tools it is possible to replace initial physical testing. This will result in cost savings, but it will also reduce the development time and material waste, since the demand of physical prototypes decreases. This thesis shows how a computer program for analyzing contact mechanics in spur and helical gears has been developed at the request of Vicura AB. The stakeholder has addressed a desire of acquiring more knowledge of contact mechanics and thereby also a request of obtaining a reliable computer based procedure for analyzing this phenomenon. A mechanical standard and a computational program have been used in order to evaluate the performance of the computer program that has been developed. The results indicate that the computer program behaves correctly, but also requires further evaluation with help of physical testing in order to completely verify the reliability of the program. In addition to the development of a computer program, the focus of the thesis has also been to investigate how gears can be designed in order to improve the contact durability. A study on how the micro geometry of a gear tooth influences the contact durability has therefore been carried out. The developed computer program has been used as an analytical tool for this study. The results from the analysis show that contact stresses in gears may be reduced by performing modifications in the lead and profile directions of a gear tooth. Key words: Computer Aided Engineering, contact mechanics, spur and helical gears Acknowledgements First of all, I would like to thank my supervisor Peter Hall for mentoring and constant support during the work with the thesis. I would also like to thank the rest of the staff at Vicura AB for encouragement and for having contributed with their knowledge within the field of mechanical engineering. I am also very grateful for the help that Sandeep Vijayakar at ANSOL has contributed with in order to solve different issues with the FE program. Finally, I would like to thank Göran Brännare for taken on the role as examiner for the project. Marcus Slogén, Trollhättan 12/6-2013 Table of Contents 1. Introduction 1 1.1 Background ................................................................................................................ 1 1.2 Problem Statement ..................................................................................................... 1 1.3 Scope and Limitations ................................................................................................ 2 2. Theory Chapter 3 2.1 Gear Design ............................................................................................................... 3 2.1.1 Spur Gear ........................................................................................................... 3 2.1.2 Helical Gear ....................................................................................................... 6 2.1.3 Micro Geometry ................................................................................................ 7 2.2 Contact Failures ......................................................................................................... 8 2.2.1 Contact Fatigue .................................................................................................. 8 2.2.2 Wear ................................................................................................................ 10 2.2.3 Plastic Deformation of the Tooth Surface ....................................................... 11 2.3 Methods used for Predicting Contact Failures ......................................................... 11 2.3.1 Contact Stress .................................................................................................. 12 2.3.2 Lubrication ...................................................................................................... 15 2.3.3 Practical Testing .............................................................................................. 18 2.3.4 Analyzing Contact Mechanics with Computer-Aided Tools ........................... 21 3. Method 23 3.1 Layout of the Study .................................................................................................. 23 3.2 AGMA Procedure for Calculating Contact Stresses in Gears .................................. 23 3.2.1 Deviations and Assumptions ........................................................................... 26 3.3 Computational Method ............................................................................................ 26 3.3.1 The FE Software .............................................................................................. 26 3.3.2 Generation of a Generalized Model ................................................................. 27 3.4 Validation ................................................................................................................. 31 3.4.1 The Studied Object .......................................................................................... 31 3.4.2 Simulation Settings .......................................................................................... 33 3.4.3 Setup of Cases ................................................................................................. 33 3.5 The Contact Program ............................................................................................... 33 3.5.1 Program Structure ............................................................................................ 34 3.5.2 The GUI ........................................................................................................... 34 3.5.3 Communication with the FE Program ............................................................. 34 3.5.4 Options for Defining the Micro Geometry ...................................................... 35 3.5.5 Estimation of Contact Stresses ........................................................................ 37 I 3.5.6 Option for Axial Misalignments ...................................................................... 37 3.6 Simulations Performed with the Contact Program ................................................... 38 3.6.1 Analysis of Different Profile Modifications’ Impact on the Contact Stresses ....... 38 3.6.2 Investigation of the Impact from Lead Modification ............................................. 40 4. Results and Discussion 43 4.1 Validation ................................................................................................................. 43 4.1.1 Discussion............................................................................................................... 44 4.2 Linear vs. Parabolic Profile Modification ................................................................ 44 4.2.1 Simulations Including Edge Contact ............................................................... 45 4.2.2 Simulations Excluding Edge Contact .............................................................. 47 4.2.3 Comparison with LDP ..................................................................................... 50 4.2.4 Discussion ........................................................................................................ 52 4.3 Investigation of the Impact from Lead Modification ............................................... 52 4.3.1 Gears without Lead Modification .................................................................... 53 4.3.2 Gears with Lead Modification ......................................................................... 55 4.3.3 Comparison of the Results ............................................................................... 58 4.3.4 Discussion ........................................................................................................ 58 4.4 Presentation of the Contact Program........................................................................ 59 4.4.1 The GUI ........................................................................................................... 59 4.4.2 Output from the Contact
Load more

Recommended publications
  • J-Integral Analysis of the Mixed-Mode Fracture Behaviour of Composite Bonded Joints
    J-Integral analysis of the mixed-mode fracture behaviour of composite bonded joints FERNANDO JOSÉ CARMONA FREIRE DE BASTOS LOUREIRO novembro de 2019 J-INTEGRAL ANALYSIS OF THE MIXED-MODE FRACTURE BEHAVIOUR OF COMPOSITE BONDED JOINTS Fernando José Carmona Freire de Bastos Loureiro 1111603 Equation Chapter 1 Section 1 2019 ISEP – School of Engineering Mechanical Engineering Department J-INTEGRAL ANALYSIS OF THE MIXED-MODE FRACTURE BEHAVIOUR OF COMPOSITE BONDED JOINTS Fernando José Carmona Freire de Bastos Loureiro 1111603 Dissertation presented to ISEP – School of Engineering to fulfil the requirements necessary to obtain a Master's degree in Mechanical Engineering, carried out under the guidance of Doctor Raul Duarte Salgueiral Gomes Campilho. 2019 ISEP – School of Engineering Mechanical Engineering Department JURY President Doctor Elza Maria Morais Fonseca Assistant Professor, ISEP – School of Engineering Supervisor Doctor Raul Duarte Salgueiral Gomes Campilho Assistant Professor, ISEP – School of Engineering Examiner Doctor Filipe José Palhares Chaves Assistant Professor, IPCA J-Integral analysis of the mixed-mode fracture behaviour of composite Fernando José Carmona Freire de Bastos bonded joints Loureiro ACKNOWLEDGEMENTS To Doctor Raul Duarte Salgueiral Gomes Campilho, supervisor of the current thesis for his outstanding availability, support, guidance and incentive during the development of the thesis. To my family for the support, comprehension and encouragement given. J-Integral analysis of the mixed-mode fracture behaviour of composite
    [Show full text]
  • Cookbook for Rheological Models ‒ Asphalt Binders
    CAIT-UTC-062 Cookbook for Rheological Models – Asphalt Binders FINAL REPORT May 2016 Submitted by: Offei A. Adarkwa Nii Attoh-Okine PhD in Civil Engineering Professor Pamela Cook Unidel Professor University of Delaware Newark, DE 19716 External Project Manager Karl Zipf In cooperation with Rutgers, The State University of New Jersey And State of Delaware Department of Transportation And U.S. Department of Transportation Federal Highway Administration Disclaimer Statement The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the information presented herein. This document is disseminated under the sponsorship of the Department of Transportation, University Transportation Centers Program, in the interest of information exchange. The U.S. Government assumes no liability for the contents or use thereof. The Center for Advanced Infrastructure and Transportation (CAIT) is a National UTC Consortium led by Rutgers, The State University. Members of the consortium are the University of Delaware, Utah State University, Columbia University, New Jersey Institute of Technology, Princeton University, University of Texas at El Paso, Virginia Polytechnic Institute, and University of South Florida. The Center is funded by the U.S. Department of Transportation. TECHNICAL REPORT STANDARD TITLE PAGE 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. CAIT-UTC-062 4. Title and Subtitle 5. Report Date Cookbook for Rheological Models – Asphalt Binders May 2016 6. Performing Organization Code CAIT/University of Delaware 7. Author(s) 8. Performing Organization Report No. Offei A. Adarkwa Nii Attoh-Okine CAIT-UTC-062 Pamela Cook 9. Performing Organization Name and Address 10.
    [Show full text]
  • AC Fischer-Cripps
    A.C. Fischer-Cripps Introduction to Contact Mechanics Series: Mechanical Engineering Series ▶ Includes a detailed description of indentation stress fields for both elastic and elastic-plastic contact ▶ Discusses practical methods of indentation testing ▶ Supported by the results of indentation experiments under controlled conditions Introduction to Contact Mechanics, Second Edition is a gentle introduction to the mechanics of solid bodies in contact for graduate students, post doctoral individuals, and the beginning researcher. This second edition maintains the introductory character of the first with a focus on materials science as distinct from straight solid mechanics theory. Every chapter has been 2nd ed. 2007, XXII, 226 p. updated to make the book easier to read and more informative. A new chapter on depth sensing indentation has been added, and the contents of the other chapters have been completely overhauled with added figures, formulae and explanations. Printed book Hardcover ▶ 159,99 € | £139.99 | $199.99 The author begins with an introduction to the mechanical properties of materials, ▶ *171,19 € (D) | 175,99 € (A) | CHF 189.00 general fracture mechanics and the fracture of brittle solids. This is followed by a detailed description of indentation stress fields for both elastic and elastic-plastic contact. The discussion then turns to the formation of Hertzian cone cracks in brittle materials, eBook subsurface damage in ductile materials, and the meaning of hardness. The author Available from your bookstore or concludes with an overview of practical methods of indentation. ▶ springer.com/shop MyCopy Printed eBook for just ▶ € | $ 24.99 ▶ springer.com/mycopy Order online at springer.com ▶ or for the Americas call (toll free) 1-800-SPRINGER ▶ or email us at: [email protected].
    [Show full text]
  • Idealized 3D Auxetic Mechanical Metamaterial: an Analytical, Numerical, and Experimental Study
    materials Article Idealized 3D Auxetic Mechanical Metamaterial: An Analytical, Numerical, and Experimental Study Naeim Ghavidelnia 1 , Mahdi Bodaghi 2 and Reza Hedayati 3,* 1 Department of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave, Tehran 1591634311, Iran; [email protected] 2 Department of Engineering, School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, UK; [email protected] 3 Novel Aerospace Materials, Faculty of Aerospace Engineering, Delft University of Technology (TU Delft), Kluyverweg 1, 2629 HS Delft, The Netherlands * Correspondence: [email protected] or [email protected] Abstract: Mechanical metamaterials are man-made rationally-designed structures that present un- precedented mechanical properties not found in nature. One of the most well-known mechanical metamaterials is auxetics, which demonstrates negative Poisson’s ratio (NPR) behavior that is very beneficial in several industrial applications. In this study, a specific type of auxetic metamaterial structure namely idealized 3D re-entrant structure is studied analytically, numerically, and experi- mentally. The noted structure is constructed of three types of struts—one loaded purely axially and two loaded simultaneously flexurally and axially, which are inclined and are spatially defined by angles q and j. Analytical relationships for elastic modulus, yield stress, and Poisson’s ratio of the 3D re-entrant unit cell are derived based on two well-known beam theories namely Euler–Bernoulli and Timoshenko. Moreover, two finite element approaches one based on beam elements and one based on volumetric elements are implemented. Furthermore, several specimens are additively Citation: Ghavidelnia, N.; Bodaghi, manufactured (3D printed) and tested under compression.
    [Show full text]
  • Gear Resonance Analysis
    GEAR SOLUTIONS GEAR MAGAZINE GEAR RESONANCE ANALYSIS Using Rapid Prototyped Gears Upgrading and Testing a 72,000 HP GEARBOX INNOVATION IN Spline Rolling Rack Tooling UNIMILL: Prototype and Bevel Gear IMTS 2014 IMTS Manufacturing SEPTEMBER 2014 SEPTEMBER Your Resource for Machines, Services, and Tooling for the Gear Industry SEPTEMBER 2014 gearsolutions.com Indiana Technology & Manufacturing Companies, Inc. (ITAMCO), left to right: Nobel Neidig - President Joel D. Neidig - Technology Manager Gary Neidig - Vice President Growth Fund. Invest in your future. Kapp Niles machines provide increased productivity to grow your business. Our machines are built for the long haul, so you can pass them down from generation to generation – with 97% of our finishing machines still in operation since 1984. Plus, our quality service and retrofitting capabilities allow you to stay current with changing technologies. Invest in Kapp-Niles and invest in the future of your business. ZPI/E: Profile grinding of internal gears with large modules. Switches from internal to exter- nal grinding by swiveling the grinding arm 1800. Wheels are dressed while in grinding position. Precise, efficient, flexible. Booth #N-7036 See us on the web! kapp-usa.com 2870 Wilderness Place | Boulder, CO 80301 p: 303.447.1130 | f: 303.447.1131 | [email protected] The most interesting man in the gear world He once climbed the Matterhorn and attended a machine run off, in Germany, on the same afternoon He has been known to hand carry parts to his secret manufacturing plant, in an unknown location But, when it comes to workholding, He always prefers König Stay productive, my friends 1921 Miller Drive Longmont, CO 80501 303-776-6212 www.toolink-eng.com OUR LINE JUST GOT LONGER..
    [Show full text]
  • JOURNAL of MECHANICAL and CIVIL ENGINEERING Shivam Bansal Mechanical Department Dronacharya College of Engineering Khentawa
    - - IJRDO - Journal of Computer Science and Engineering ISSN: 2456-1843 JOURNAL OF MECHANICAL AND CIVIL ENGINEERING GEARS Shivam Bansal Mechanical Department Dronacharya College of Engineering Khentawas, Farukhnagar,Gurgaon [email protected] Yogesh Vashiath Mechanical Department Dronacharya College of Engineering Khentawas, Farukhnagar,Gurgaon [email protected] Ujjwal Batra Mechanical Department Dronacharya College of Engineering Khentawas, Farukhnagar,Gurgaon [email protected] INTRODUCTION A gear or cogwheel is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque, in most cases with teeth on the one gear being of identical shape, and often also with that shape on the other gear. Two or more gears working in tandem are called a transmission and can produce a mechanical advantage through a gear ratio and thus may be considered a simple machine. Geared devices can change the speed, torque, and direction of a power source. The most common situation is for a gear to mesh with another gear; however, a gear can also mesh with a non-rotating toothed part, called a rack, thereby producing translation instead of rotation. The gears in a transmission are analogous to the wheels in a crossed belt pulley system. An advantage of gears is that the teeth of a gear prevent slippage. When two gears mesh, and one gear is bigger than the other (even though the size of the teeth must match), a mechanical advantage is produced, with the rotational speeds and the torques of the two gears differing in an inverse relationship. In transmissions which offer multiple gear ratios, such as bicycles, motorcycles, and cars, the term gear, as in first gear, refers to a gear ratio rather than an actual physical gear.
    [Show full text]
  • RHEOLOGY and DYNAMIC MECHANICAL ANALYSIS – What They Are and Why They’Re Important
    RHEOLOGY AND DYNAMIC MECHANICAL ANALYSIS – What They Are and Why They’re Important Presented for University of Wisconsin - Madison by Gregory W Kamykowski PhD TA Instruments May 21, 2019 TAINSTRUMENTS.COM Rheology: An Introduction Rheology: The study of the flow and deformation of matter. Rheological behavior affects every aspect of our lives. Dynamic Mechanical Analysis is a subset of Rheology TAINSTRUMENTS.COM Rheology: The study of the flow and deformation of matter Flow: Fluid Behavior; Viscous Nature F F = F(v); F ≠ F(x) Deformation: Solid Behavior F Elastic Nature F = F(x); F ≠ F(v) 0 1 2 3 x Viscoelastic Materials: Force F depends on both Deformation and Rate of Deformation and F vice versa. TAINSTRUMENTS.COM 1. ROTATIONAL RHEOLOGY 2. DYNAMIC MECHANICAL ANALYSIS (LINEAR TESTING) TAINSTRUMENTS.COM Rheological Testing – Rotational - Unidirectional 2 Basic Rheological Methods 10 1 10 0 1. Apply Force (Torque)and 10 -1 measure Deformation and/or 10 -2 (rad/s) Deformation Rate (Angular 10 -3 Displacement, Angular Velocity) - 10 -4 Shear Rate Shear Controlled Force, Controlled 10 3 10 4 10 5 Angular Velocity, Velocity, Angular Stress Torque, (µN.m)Shear Stress 2. Control Deformation and/or 10 5 Displacement, Angular Deformation Rate and measure 10 4 10 3 Force needed (Controlled Strain (Pa) ) Displacement or Rotation, 10 2 ( Controlled Strain or Shear Rate) 10 1 Torque, Stress Torque, 10 -1 10 0 10 1 10 2 10 3 s (s) TAINSTRUMENTS.COM Steady Simple Shear Flow Top Plate Velocity = V0; Area = A; Force = F H y Bottom Plate Velocity = 0 x vx = (y/H)*V0 .
    [Show full text]
  • 1 Classical Theory and Atomistics
    1 1 Classical Theory and Atomistics Many research workers have pursued the friction law. Behind the fruitful achievements, we found enormous amounts of efforts by workers in every kind of research field. Friction research has crossed more than 500 years from its beginning to establish the law of friction, and the long story of the scientific historyoffrictionresearchisintroducedhere. 1.1 Law of Friction Coulomb’s friction law1 was established at the end of the eighteenth century [1]. Before that, from the end of the seventeenth century to the middle of the eigh- teenth century, the basis or groundwork for research had already been done by Guillaume Amontons2 [2]. The very first results in the science of friction were found in the notes and experimental sketches of Leonardo da Vinci.3 In his exper- imental notes in 1508 [3], da Vinci evaluated the effects of surface roughness on the friction force for stone and wood, and, for the first time, presented the concept of a coefficient of friction. Coulomb’s friction law is simple and sensible, and we can readily obtain it through modern experimentation. This law is easily verified with current exper- imental techniques, but during the Renaissance era in Italy, it was not easy to carry out experiments with sufficient accuracy to clearly demonstrate the uni- versality of the friction law. For that reason, 300 years of history passed after the beginning of the Italian Renaissance in the fifteenth century before the friction law was established as Coulomb’s law. The progress of industrialization in England between 1750 and 1850, which was later called the Industrial Revolution, brought about a major change in the production activities of human beings in Western society and later on a global scale.
    [Show full text]
  • What Engineers Should Know About Bending Steel
    bending and rolling What Engineers Should Know About Bending Steel With these tips under your belt, you’ll be ahead of the curve on your next bending or rolling project. BY TODD A. ALWOOD HOW MUCH DO YOU KNOW ABOUT BENDING STRUCTURAL STEEL? Do you know what you need to show on con- struction drawings to transfer the idea of what the result should actually look like? Do you know how tight of a radius you Hcan roll a W12×19, and what to expect it to look like? If you have bending questions, who do you ask? AISC’s bender-roller com- mittee is taking steps to address these ques- tions, which are coming up more and more within the structural steel industry. Bender = Fabricator? Not so! The bender is typically a spe- cialty subcontractor of the fabricator. Benders receive the steel from the fabri- cator (or sometimes furnish it themselves), and then ship the curved steel back to the fabricator. Benders usually have limited fabrication capabilities, such as hole drill- ing and plate welding, but they are gener- ally used for smaller jobs that usually are not structural in nature. Typical fabrication is still carried out through the main project fabricator who organizes the steel package from procurement through delivery to the site for erection. Kottler Metal Products, Inc. Kottler Metal Products, Todd Alwood is the senior advisor for AISC’s Steel Solutions Center and is Secretary of AISC’s Bender-Roller Committee. MODERN STEEL CONSTRUCTION MAY 2006 Common Terminology and Essential Dimensions for Curving Common Hot-Rolled Shapes There’s only one type of bending, right? Nope! There are five typical methods of bending in the industry: roll- ing, incremental bending, hot bending, rotary-draw bending, and induc- tion bending.
    [Show full text]
  • Chapter 8 Gears
    Gears CHAPTER 8 Chapter 8 Gears Chapter Objectives When you have finished Chapter 8, “Gears,” you should be able to do the following: 1. Understand the purpose of gears and drives. 2. Identify five gear design categories and their orientation types. 3. Describe and compare various gear types, including: spur helical, herringbone, straight bevel, spiral bevel, cylindrical worm, double-enveloping worm, cycloidial, and hypoid. 4. Define the most common gear terms. 5. Explain the application requirements when selecting gears. 6. List the important specifications needed when ordering gears. 7. List five causes for gear tooth failure. 8. Name the associations that standardize gear classification. 9. Describe and compare the basic types of enclosed gear drives. 10. Explain the function and importance of seals and breathers for enclosed gears. 11. Describe the purpose and the lubrication essential for gear life. 12. Explain gear rating standards. 13. Explain the major factors for selecting and installing gear drives. Power Transmission Handbook 8-155 – Gears Introduction Open Gears A gear is a rotating machine part having cut teeth, or cogs, Gears are grouped into five design categories: spur, helical, which mesh with another toothed part in order to transmit bevel, hypoid, and worm. They are also classified according torque. Two or more gears working in tandem are called to the orientation of the shafts on which they are mounted, a transmission and can produce a mechanical advantage either in parallel or at an angle. Generally, the shaft orien- through a gear ratio and thus may be considered a simple tation, efficiency, and speed determine which type should machine.
    [Show full text]
  • Elastic Metamaterials for Independent Realization of Negativity in Density
    Elastic metamaterials for independent realization of negativity in density and stiffness Joo Hwan Oh1, Young Eui Kwon2, Hyung Jin Lee3 and Yoon Young Kim1, 3* 1Institute of Advanced Machinery and Design, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-744, Korea 2Korea Institute of Nuclear Safety, 62 Gwahak-ro, Yuseoung-gu, Daejeon 305-338, Korea 3School of Mechanical and Aerospace Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-744, Korea Abstract In this paper, we present the realization of an elastic metamaterial allowing independent tuning of negative density and stiffness for elastic waves propagating along a designated direction. In electromagnetic (or acoustic) metamaterials, it is now possible to tune permittivity (bulk modulus) and permeability (density) independently. Apparently, the tuning methods seem to be directly applicable for elastic case, but no realization has yet been made due to the unique tensorial physics of elasticity that makes wave motions coupled in a peculiar way. To realize independent tunability, we developed a single-phased elastic metamaterial supported by theoretical analysis and numerical/experimental validations. Keywords: Elastic metamaterial, Independently tuning parameters, Negative density, Negative stiffness PACS numbers: 46.40.-f, 46.40.Ff, 62.30.+d * Corresponding Author, Professor, [email protected], phone +82-2-880-7154, fax +82-2-872-1513 -1- Interest in negative material properties has initially grown in electromagnetic field1-3, being realized by metamaterials. Since then, several interesting applications in antennas, lenses, wave absorbers and others have been discussed. The advances in electromagnetic metamaterials are largely due to independent tuning of the negativity in permittivity and permeability.
    [Show full text]
  • General Applications of Gears
    UNIT - III GEAR MANUFACTURING PROCESS SPRX1008 – PRODUCTION TECHNOLOGY - II Gears are widely used in various mechanisms and devices to transmit power and motion positively (without slip) between parallel, intersecting (axis) and non-intersecting non parallel shafts, •without change in the direction of rotation •with change in the direction of rotation •without change of speed (of rotation) •with change in speed at any desired ratio Often some gearing system (rack – and – pinion) is also used to transform Rotary motion into linear motion and vice-versa. Fig.1 Features of Spur Gear Gears are basically wheels having, on its periphery, equispaced teeth which are so designed that those wheels transmit, without slip, rotary motion smoothly and uniformly with minimum friction and wear at the mating tooth – profiles. To achieve those favorable conditions, most of the gears have their tooth form based on in volute curve, which can simply be defined as Locus of a point on a straight line which is rolled on the periphery of a circle or Locus of the end point of a stretched string while its unwinding over a cylinder as indicated in Fig. General Applications of Gears Gears of various type, size and material are widely used in several machines and systems requiring positive and stepped drive. The major applications are: • Speed gear box, feed gear box and some other kinematic units of machine tools • Speed drives in textile, jute and similar machineries • Gear boxes of automobiles • Speed and / or feed drives of several metal forming machines • Machineries for mining, tea processing etc. • Large and heavy duty gear boxes used in cement industries, sugar industries, cranes, conveyors etc.
    [Show full text]