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Mechanical Engineering Drawing

Mechanical Engineering Drawing 1
WELCOME TO MECH 211, Mechanical Engineering Drawing Time: M W 10:15 11:30 Credits: 3.5 Session: Fall 2013 Introduction Lecture 1 Whatever area you will choose… This course is fundamental. A bit of history • The objective need to communicate A bit of history • The time line History in images Artistic Drawing “Paper could take about anything” Observe the way the posts are crossing Have you ever seen such a construction The fundamental difference Artistic Drawing Mechanical/Technical drawing Content of the Course Introduction to graphic language and design — means and techniques. The third and the first angle projections. Orthographic projection of points, lines, planes and solids. Principal and auxiliary views. Views in a given direction. Sectional views. Intersection of lines, planes and solids. Development of surfaces. Drafting practices. Dimensioning, fits and tolerancing. Computeraided drawing and solid modelling. Working drawings — detail and assembly drawing. Design practice. Machine elements representation. Case Study A, B, C, D ARE POINTS Content of the Course A D B CA, B, C, D ARE POINTS Content of the Course AB, BC, CD, DA, CA ARE LINES A D B CA, B, C, D ARE POINTS Content of the Course AB, BC, CD, DA, CA ARE LINES A ABC, CDA ARE PLANES D B CA, B, C, D ARE POINTS Content of the Course AB, BC, CD, DA, CA ARE LINES A ABC, CDA ARE PLANES ABCD IS A SOLID D B CContent of the Course A, B, C, D ARE POINTS AB, BC, CD, DA, CA ARE LINES A ABC, CDA ARE PLANES CASE ABCD IS A SOLID STUDY INTERSECTION D PERSPECTIVE ISOMETRIC COMMUNI EXPLAIN GRAPHICS CATION WITH TEXT B C DEVELOP MENT PARALLEL PROJECTION ARTISTIC TECHNICALMission of the Course • Enables the students to learn the techniques and standard practices of technical graphics • At the end of the lectures, one would be able to: – Read a working or assembly drawing (blueprint) – Represent mechanical components in multiview orthographic representation – Create conceptual design sketches – Create assembly drawings (limited) – Capability to use AutoCAD for 2D representations The amount of acquired skills will be proportional to the capabilities, will and effort of the individuals Main Objective of the Course • To acquire essential skills that are part of the mechanical engineering practice • To be able to communicate with other mechanical engineering professionals regardless their spoken language • To be able to communicate with manufacturers of mechanical systems Class Logistics • 3 teaching hours/week MW 10:15 –11:30 • 12 weeks and one Review week • 2 hour of tutorial – following the class • 4 hours of laboratory – every 4 Weeks • 3 parallel sections Class Materials Required textbook Recommended textbook Class Materials • Tutorial materials – handed in during tutorial periods, also available on the web. Tutorials will be held in AUTOCAD labs and set of practicing drawings available on the web site to learn AUTOCAD • Assignments: 8 – available on the internet • Solutions to the assignments will be with PODs after assignment due date • RECOMMENDATION: Attend the classes Class Materials Lect Textbook Description Chapter 1 1, 6 Introduction to graphic language and design, means and techniques, views of a geometric object, multiview projections, applications and examples ,  2 2, 3, 4 Instruments, geometric constructions, CAD tools, demonstration examples ,  3 5, 7, 8, 10 Sketching and shape description, shape generation, sectional and auxiliary views, examples and applications ,  4 19 Descriptive Geometry– Points and lines, examples   5 19 Descriptive Geometry – Points and lines, examples ,  6 20 Descriptive Geometry – Parallelism perpendicularity – examples ,  7 21 Descriptive Geometry – Solids in space and Intersections – examples ,  8 21, 22 Descriptive Geometry – Intersections, examples, ,  9 22 Descriptive Geometry – Developments, examples, ,  10 11, 12 Dimensioning and tolerancing, examples and applications ,  11 13 Threads, fasteners, springs, gears, examples ,  12 14 Design and working drawings – examples, Design case study ,  13 Makeup class, Review–,  During the tutorial period of week 8, the midterm test will be carried  PowerPoint presentation,  Material available on course website,  Lecture to be done on board/screen Class Instructor and Contacts Instructor: Dr. S. Narayanswamy Office: EV Building Room: 004 –124 Phone: 8482424 (7923) Office Hours: J 10:00 –12:00 or by appointment email: Course Web Site: What you have to do • Attend the lectures, laboratories and tutorials – try to understand the objectives as well as the procedures • Use time at home to read and study the chapters in the book – use the material posted on the internet • Do your homework by yourself – consult only your colleagues, tutor, lab instructor or class instructor • Submit on time your assignments • Write the midterm test – this is a good measurement means for your performance in the class • Write the final exam with confidence that you will do very well Midterm Exams th • Scheduled for October 28 , 2013 and it will be conducted during the tutorial period. • The midterm test is not mandatory but is recommended • If the midterm result is better than the final, it will be counted for 10 towards final grade. Laboratory • There is lab component to this course • You will be learning about few machineries • There are four of them done in H1067 once 4 weeks (4 hours a week). • Safety is important and the details are available in the course outline. Grading Scheme • To pass, it is imperative to work during the term. • The following grading scheme will be used for those who wrote the midterm and their grade is higher than the grade in the final: – Assignments: 16 – Midterm Examination: 10 – Laboratory 14 – Final Examination 60 • who do not write the midterm or their midterm grade in below the final: – Assignments: 16 – Laboratory 14 – Final Examination 70 Content of the first lecture • Graphics as communication means • A bit of history • Multiview representation and orthographic projections • Technical procedures • How to generate multiview orthographic projection • Representation rules Mechanical components Geometry is a fundamental thing In Nature In Human Need • Introduction to Graphic Language and Design • Why graphics is necessary – Communicate information that would not be possible to exchange in writing • Why not use pictures to communicate visual information – Usually, a drawing represents something that exists just at conceptual level • Why not use pictorial representation – The information contained in a drawing must be used to build an accurate component/system. What is Drawing • Drawing is a graphic representation of a real thing, an idea, or a proposed design • Why graphic representation • Graphic method of representation is a basic natural form of communication of ideas that is universal and timeless. • It is impossible to explain things through text. Graphic Language A simple component • How hard to define in words • Try to describe in words the following representation: A MECHANISM Graphic Language • Graphics language is universal Graphic Language • The information can be conveyed regardless the spoken language 1. Ÿog¿® 4. ™ y²î‰※ 7. ÐzC êÑÒ¶³²² 10. ™¥¢ ®¼ 2. ÐŷƁţāŖĉ 5. Z´¶ æÊ¿£ŠŠŠ 8. šëŢŪųĺ З— 11. ※—‘…€ 3. ®µ¶œƒ/ 6. €¶¸¹ì±®wdÊ ;8 9. €ßu ” éÐÐ Graphic Language • When spoken language is known, the information is more accurate Essentials of a good drawing • Should represent the concept/idea/geometry clearly • Should be able to communicate with others with out doubt • Should respect the manufacturing feasibility • Should favor a lot standardization Let’s see how to make a good mechanical drawing Views • An object could be represented in more ways: Projections/ Drawing Basics • The way one is visualizing an object (Simple and sufficient) • Two basic projection types – use parallel projection Parallel Perspective Projections and views (brief) What is perspective representation • Representation of objects based on the rule of distance: 2 identical object are seen different from different distances – shape is deformed too • This type of representation is not used for technical purposes in Mechanical Engineering What should be drawn • What is seen – follow certain rules Views Multiview representation Project the visible and hidden edges/corners Views Multiview representation Multiviews • A part is represented in multiple views (a single part is seen as more than one part) • The representation makes the user to fully understand the shape of the part, to perceive the relative proportions of the geometric features and to position the features one with respect to another • The parallel projection principle and the alignment of the features is used in the representation Type of Projections Projection planes • The component is aligned with respect to the principal projection planes – Top (T) or Horizontal (H) – Front (F) or Vertical (V) – Side (S) or Profile (P) • The projection is carried such that each feature parallel to the projection planes to be seen as true length Object orientation Projection principles Projection principles Projection Types Third angle projection First angle projection Relative position of the views • All views must be aligned with respect to each other – feature to feature Drafting strategies (3 view) Technical procedures • When representing the third view, scale, divider of miter line is used to ensure the alignment of the three views Example • Represent the shown component using multiple view representation Example • Start with the front view • The edge C cannot be seen but is represented by a dashed line (hidden feature) C Example • Align the top view with respect to the front view C Example • Complete the representation • Later, dimensioning and comments will be added to the drawing The principal projection planes • The object should be aligned with respect to the projection planes The principal projection planes unfolded • Notice the relationship between the features • The depth – distance from the front to the object is measured in the Horizontal and Profile Multiview Projection Drawing How to generate • Assume the given part as shown besides. • Position the part in a convenient way, to simplify the representation as much as possible Multiview Projection Drawing How to generate • Select the position of the projection planes • Start with one of the projections – usually the front view • Each edge is represented based on the principle of the parallel projection Multiview Projection Drawing How to generate • Complete the first view. • Use the basic representation Principles: • visible edge is seen as a full line • nonvisible feature is represented by a dashline • axes of symmetric features are represented by dashdot lines Multiview Projection Drawing How to generate • Continue with the second view • Make sure that you have accurately align the two views. • Use the same rules for representation. • The alignment lines must be perpendicular to the edge of the projection planes • (The lines of sight are always perpendicular to the fold line). Multiview Projection Drawing How to generate • Continue with the third view • Make sure that you have accurately align all views. • Use the same rules for representation. • The alignment lines must be perpendicular to the edges of the projection planes • (The lines of sight are always perpendicular to the corresponding fold lines). Multiview Projection Drawing How to generate • Complete the representation • Separate the top from the profile view along the edge (fold line) • Unfold the three views to lay them on the same plane Multiview Projection Drawing How to generate • This is the 3view orthographic representation of the selected part (FLANGE) • Do not erase any of the lines when writing a test Orthographic multiview • The above part will be projected on all 6 projection planes Orthographic multiview Orthographic multiview Orthographic multiview Orthographic multiview Orthographic multiview Solid models Minimum number of views • Certain shapes could be described in less number of views • One must use the minimum number of views for representation Minimum number of views • Do not produce more views than necessary Centerline • Axisymmetric features are indicated with a dashpoint line CENTERLINE Hints on understanding shapes • Try to “see” the way a solid is created out of primitives Hints on understanding shapes • Complex shapes could be generated using Boolean operations Pay attention to edges Projections and views (brief) Where drawing is used • It is important to know the rationale of drawing • Drawing is an international communication language • Fast way to convey certain type of information • Limited number of concepts are better represented by drawing, but not all The design process • Drawings are created to represent parts that do not exist yet • The designed parts are intended to be manufactured • The drawings must carry all the necessary information that enables the fabrication of the part The design process • Design involves constrained creation • Constraints: • Technology limits • Human and environment concerns • Durability and reliability • Cost • Market requirements • Etc. The design process • REPRESENTATION • PERCEPTION Basic requirements to be able to • KNOWLEDGE perform a design • INTUITION All the above interacts in your judgment even if you are not • CONCEPT aware of it • PURE CONCEPT You have to train your judgment • EMPIRICAL CONCEPT to be able to perform solution • NOTION solving based thinking • IDEA The graphic helps you to do so The design process • A design is created after analysis, full understanding of requirements and constraints and synthesis • Two individuals may not come with the same solution to the same problem • Example: Connect two straight pipes ND 4” to avoid leaking of the gas and to permit easy maintenance of the segment Solutions to the problem • Multiple: flanges, clips, clamps, seals, etc. 1. Problem Defn. 2. Concept and The design process ideas 3. Solutions 4. Models/Prototype 5. Production and working drawings Concurrent engineering approach The design process The design process Drawings in product development Designer Sketches Vendors/ Mechanical Customers Production Engineer Shops Assembly Assembly Drawings Drawings Quality Assembly Assurance Functional Drawings Prod. drawings Drawings in product development A Component
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