1、出版社 国际合作 出 部 版社 国际合作部工程制图基础工程制图基础出版社 国际合作部A new machine，or product must exist in the mind of the engineer or designer before it becomes a reality.This original concept or idea is usually placed on paper called drawing paper to form engineering drawing.The engineers or designers can communicate each
2、other with the engineering drawing.Chapter 1 Basic Skills of Engineering Drawing出版社 国际合作部1.1 Drawing Instrument1.1.1 Drawing pencilsA good drawing begins with a proper drawing pencil and its correct use.Pencil grade ranges from the hardest,9H,to the softest,7B.Grade H,HB and B are most frequently us
3、ed because of their medium hardness.The choice of the proper drawing pencils depends on personal preference and the drawing paper used.出版社 国际合作部Fig.1.1 Sharpen drawing pencils correctly.出版社 国际合作部1.1.2 Pencil eraserFig.1.2 Erasing shield.出版社 国际合作部1.1.3 Erasing shield擦图片1.1.4 Triangles三角板Fig.1.3 Trian
4、gle.出版社 国际合作部Fig.1.4 Parallel line construction出版社 国际合作部Fig.1.5 Perpendicular line Construction.出版社 国际合作部1.1.5 Compass圆规Fig.1.6 Compass.出版社 国际合作部1.1.6 Divider分规Fig.1.7 Divider.出版社 国际合作部Fig.1.8 Using divider.出版社 国际合作部1.1.7 Drawing board 图板Fig.1.9 Drawing board.出版社 国际合作部1.1.8 T square 丁字尺Fig.1.10 T-sq
5、uare.出版社 国际合作部Fig.1.11 Drawing a horizontal line.出版社 国际合作部Fig.1.12 Drawing a vertical line.出版社 国际合作部1.2（Provisions of Chinese NationalStandard of Technical Drawing（机械制图国 家标准的规定）1.2.1 Drawing paper（GB/T 146891993）1.2.1.1 Drawing paper size（图幅）The sizes of the drawing papers together with their length
6、s,widths and letter designations,are listed in Chart 1.1.出版社 国际合作部Chart 1.1 Paper size出版社 国际合作部1.2.1.2 Paper frame format（图框格式）Fig.1.13 Format of paper frame.出版社 国际合作部1.2.2 Title block（标题栏）Fig.1.14 Papers located vertically.出版社 国际合作部Fig.1.15 Title block出版社 国际合作部1.2.3 Measurement units for engineerin
7、g（工 程计量单位）1.2.3.1 Metric system（SI）of unitsFig.1.16 The centimeter.出版社 国际合作部1.2.3.2 English system of unitsFig.1.17 English units.出版社 国际合作部1.2.4 Scales（比例）（GB/T 146901993）Chart 1.2 Scales出版社 国际合作部1.2.5 Characters（字体）（GB/T 146911993）1.Height and number of a character（字高和字号）2.Chinese characters（汉字）Fig
8、.1.18Chinese characters in font of“长仿宋体”.出版社 国际合作部Chart 1.3 Basic stroke in Chinese characters and the witten orders出版社 国际合作部1.3 Basic stroke in Chinese characters and the witten orders1.2.5.3 Letters and numbers（字母和数字）Letters and numbers may be written in italic（斜体）or vertical（直体）.Italics are frequ
9、ently applied in engineering drawing.Italic numbers are shown in Fig.1.19;#italic capitals in Fig.1.20;#italic small letters in Fig.1.21;#italic Grecian（希腊的）letters in Fig.1.22 and Roman numerals in Fig.1.23.出版社 国际合作部Fig.1.19 Italic numbers.Fig.1.20 Italic capitals.出版社 国际合作部Fig.1.21 Italic small let
10、ters.Fig.1.22 Italic Grecian letters.出版社 国际合作部Fig.1.23 Italic Roman numerals.1.2.6 Drawing lines（图线）（GB/T1 7450 1998）Each line on an engineering drawing has a definite meaning and is drawn in a certain way.Chart 1.4 shows various lines required in the engineering drawing.出版社 国际合作部Chart 1.4 Lines req
11、uired in engineering drawing出版社 国际合作部Fig.1.24 Application of all types of lines.出版社 国际合作部Fig.1.25 Correct and incorrect drawings出版社 国际合作部1.2.7 Dimension（尺寸）1.2.7.1 Dimension composition（尺寸的组成）Fig.1.26 Dimension terms.出版社 国际合作部Fig.1.27 Arrowheads.出版社 国际合作部Fig.1.28 Correct and incorrect in dimensionin
12、g.出版社 国际合作部1.2.7.2 Common dimension symbols（Chart 1.5）Chart 1.5 Common dimension symbols出版社 国际合作部1.3 Geometric Construction（几何构造）Simple geometrical structures should be familiar to engineers for they occur frequently in engineering drawing.For example,how to draw a tangent arc?#or a hexagon?#Geometr
13、ical graphics are two dimensional figures which are composed of straight lines,curves,or the combination of them.Geometric constructions in this chapter include tangent arcs,regular polygons,ellipses and so on.出版社 国际合作部1.3.1 How to draw tangent pointsStep 1 Draw a line tangent to the circle withcent
14、er E,which is tangent line ABas shown in Fig.1.29（a）.Step 2 From center E,draw a line perpendicular to tangent line AB to locate tangent point T（Fig.1.29（b）.Step 3 Connect two centers E and D to locate tangent point P between two tangent circles （Fig.1.29（b）.出版社 国际合作部Fig.1.29 Tangent points.出版社 国际合作
15、部1.3.2 How to draw a line tangent to a circle through a point on the given circleStep 1 Arrange a triangle in combination with the T-square（or another triangle）so that its hypotenuse passes through center Oand point C.Step 2 Holding the T-square firmly in place,turn the triangle about its square cor
16、ner and move it until the hypotenuse passes through C.Step 3 Draw the tangent line required along the hypotenuse（Fig.1.30（b）出版社 国际合作部Fig.1.30 A line tangent to a circle through a point on a circle.出版社 国际合作部1.3.3 How to draw a line tangent to a circle through a point outside thegiven circleStep 1 Connect points O and P,and then locate point D by bisecting OP（Fig.1.31 （b）.Step 2 With point D as center and OD as the radius,draw a semicircle to intersect the given arc tangent point at T,（Fig.1.31 （c）.Ste
