Chapter 1 Introduction

Transcription

1 Chapter 1 Introduction

2 Contents Engineering drawing Drawing standards Drawing sheet Scale Lettering Line types

3 Engineering Drawing Contents

4 Engineering Drawing

5 Effectiveness of Graphic Language 1. Try to write a description of this object. 2. Test your written description by having someone attempt to make a sketch or visualize from your description. You can easily understand that The word language is inadequate for describing the size, shape and features completely as well as concisely.

6 Graphic Language in Engineering Drawing Engineering drawing or blueprint uses lines to represent the features of an object. Features of an object are surface (include plane) and edge. Surface Edge

7 Ways to Create an Engineering Drawing A drawing can be created in 3 ways 1. Freehand sketch 2. Using typical drawing instruments 3. Using a computer

8 Create a Drawing : Freehand sketch The lines are drawn using only pencil and erasers on a blank or grid paper. Example Pictorial sketch Orthographic sketch

9 Create a Drawing : Using instruments Drawing instruments are used to draw straight lines, circles, and curves concisely and accurately. Drawings are usually made to scale. Example

10 Create a Drawing : Using a computer Computer aided drafting (CAD) software is used. Example 2D drawing Solid modeling

11 Elements of a Drawing A clear and precise engineering drawing requires both graphics and word languages. Graphics language Describe a shape (mainly). Word language Describe an exact size, location and specification of the object.

12 Text on drawings : Example Dimensions & Notes General notes Title block

13 Knowledge and Skills Require Engineering Drawing Graphics language Word language Geometric construction Using line types Projection method Visualization Dimensions & Notes Visualization is the ability to mentally picture things that do not exists. Contents

14 Drawing Standard Drawing sheet Scale Lettering Line types Contents

15 Definition and Necessity Drawing standards are set of rules that govern how technical drawings are represented. Drawing standards are used so that drawings convey the same meaning to everyone who reads them.

16 Standard Code Country Code Full name USA Japan UK Australia Germany ANSI JIS BS AS DIN ISO American National Standard Institute Japanese Industrial Standard British Standard Australian Standard Deutsches Institut für Normung International Standards Organization

17 Drawing Standard Drawing Sheet Drawing standard Contents

18 Drawing Sheet : Standard size Trimmed paper of a size A0 ~ A4. Standard sheet size (JIS) A4 210 x 297 A3 297 x 420 A2 420 x 594 A1 594 x 841 A0 841 x 1189 (Dimensions in millimeters) A4 A3 A2 A1 A0

19 c c Drawing Sheet : Orientation & Margin 1. Type X (A0~A4) Sheet size c (min) d (min) Border lines d 2. Type Y (A4 only) Drawing space c Title block A A A A A d Drawing space Title block

20 Drawing Standard Drawing Scale Drawing standard Contents

21 Drawing Scales : Definition Length, size Scale is a ratio between the linear dimension of a drawn representation of an object and the actual object. 1 : 2 Drawing Actual

22 Drawing Scales : Designation Designation of a scale consists of the word SCALE followed by the indication of its ratio, as follows SCALE 1:1 for full size SCALE X:1 (X > 1) for an enlargement scales SCALE 1:X (X > 1) for a reduction scales Drawing scale is commonly found in a title block.

23 Drawing Scales : Notes Dimension numbers shown in the drawing represent the true size of an object and they are independent of the drawing scale used.

24 Drawing Scales : Standard scale Standard reducing scales are 1:2, 1:5, 1:10, 1:20, 1:50, 1:100 Standard enlarging scales are 2:1, 5:1, 10:1, 20:1, 50:1, 100:1

25 Drawing Standard Lettering Drawing standard Contents

26 Recommendation Text s style on the drawing must have the following 2 properties Legibility - Shape - Space between letters - Space between words Uniformity - Size (or text height) - line thickness Examples GOOD Not uniform in style. Not uniform in height. Not uniformly vertical. Not uniform in thickness of stroke. Inappropriate space between letters

27 Style (this course) Gothic vertical style. Begin the sentence, phrase or word with a capital letter. Text height 3~5 mm. Space between lines of text is about of text height. Height of the lower-case letter is about 2/3 of that of a capital letter.

28 Basic Strokes Straight Slanted Horizontal Curved Examples I letter A letter B letter

29 Suggested Upper-case Strokes Letters & Sequence Numerals Straight line letters Curved line letters & Numerals

30 Lower-case Letters

31 Stroke Sequence : Upper-case I L T F E H Skip section

32 Stroke Sequence : Upper-case V X W Skip section

33 Stroke Sequence : Upper-case N M K Z Y A 4 Skip section

34 Stroke Sequence : Upper-case O Q C G Skip section

35 Stroke Sequence : Upper-case D U P B R J Skip section

36 Stroke Sequence : Upper-case Skip section

37 Stroke Sequence : Upper-case S Skip section

38 Stroke Sequence : Lower-case l i Skip section

39 Stroke Sequence : Lower-case v w x k z Skip section

40 Stroke Sequence : Lower-case j y f t r Skip section

41 Stroke Sequence : Lower-case c o a b d p q e Skip section

42 Stroke Sequence : Lower-case g n m h u s Skip section

43 Word Composition Space between the letters depends on the adjacent contour of the letters. Non-uniform spacing DRAWING Uniform spacing D R A W I N G Word having Non-uniform spacing is more readable.

44 Spacing Word Composition DRAWING Contour Contour can be denoted as straight, slant and curve. Adjacent contour can be 1. straight-straight : II, IN, IM, IP etc. 2. straight-curve (or curve-straight) : IO, QR etc. 3. straight-slant (or slant-straight) : IV, IW etc. 4. curve-curve : OO, OG etc. 5. slant-curve (or curve-slant) : VO, WG, VC etc. 6. slant-slant : VW, VX etc.

45 Sentence Composition Leave the space between words equal to the space requires for writing a letter O. Example ALL O DIMENSIONS O ARE O IN MILLIMETERS O UNLESS OTHERWISE O SPECIFIED.

46 Drawing Standard Line Types Drawing standard Contents

47 Basic Line Types & Name according to application Thickness Thick Thin 1. Dimension line Style Continuous Dash Chain Visible line 2. Extension line 3. Leader line Hidden line Center line 1. Visible line 2. Dimension line Extension line Leader line represent features that can be seen in the current view. indicate the sizes and location of features. 3. Hidden line 4. Center line represent features that can not be seen in the current view. represents symmetry, path of motion, centers of circles, axis of axisymmetrical parts

48 Example Contents