第1章几何作图

依次连接1、2、3、4、5、6
点即得正六边形。
6
请点击鼠标左键显示后面内容
3
4
5
Equilateral polygon 正多边形
13
2) Construct two regular hexagons (DIA 40mm=A/C or A/F of HEX)
作两个正六边形(其外/内接圆直径d为40mm=正六边形对角/边距)。
圆弧与圆弧连接(外切)
请点击例题显示其内容
O内
Internal arc connection between two pieces of arcs
圆弧与圆弧连接(内切)
Arc connection 圆弧连接
6
There are three cases, i.e. 圆弧连接有三种基本形式
1. Arc connection between two lines. 用圆弧连接两条已知直线。
作正六边形, (其外接圆直径d为40mm=正六边形对角距)
Steps 作图步骤：
2
1.To divide the circumcircle.
分别以中心轴线的二端点1、
4为圆心,以 D/2 为半径画
圆弧,求得与外接圆的交点 2、3、5、6点；
2.Join these points to form
1
d
the hexagon.
Example: Drawing of slope ( 1∶8, upon point 0 5mm left 100mm).
过O点左100mm、上5 mm之点作斜度为 1∶8的斜线。
1∶8
5 10
0
80
100
请点击鼠标左键显示后面内容
30 10
H d
Slope and taper 斜度和锥度
Fra Baidu bibliotek
4
作两个正六边形(其外/内接圆直径d 为40 mm=正六边形对角/边距)。
2. Equilateral polygon 正n 边形的画法
1) Given the distance across corners, draw a positive pentagon (n = 5).
已知其外接圆直径,作正五边形（n =5）。
2) Define the scale, select the size of drawing sheet, and fix the drawing sheet on the drawing board.
确定比例，选定图幅，固定图纸。
3) Draw the border lines and produce the title box.
作图原理 圆弧连接作图的关键在于, 找出连接弧的圆心位置 及与两被连接线段连接处的切点位置。
R2 O
a
R2 a
O
R1
O
a
R1
Arc connection between two lines
圆弧连接两已知直线
O外
External arc connection Between two pieces of arcs
请点击鼠标左键显示后面内容
Equilateral polygon 正多边形
14
1) Given the distance across corners, draw a positive pentagon (n = 5).
Geo几metr何ic Co作nstr图uction
Equilateral polygon
正多边形
Slope and taper
斜度和锥度
Arc connection
圆弧连接
Techniques for drawing 2D objects 平面图形的画法
Exercise
练习题
请点击相应标题显示其内容
L
The slope symbol (符号): 30 1∶n
When dimensioning, the oblique direction of the slope symbol should be in accordance with the actual slope direction.
(标注时要注意符号斜线方向与斜度方向一致)
5
The so-called arc connection is often used for smooth connection between lines and circles using arcs.
所谓圆弧连接，是指由一圆弧光滑地连接相邻两线段（或圆弧）的作图方法。
Construct principle: The key in tangency principle is to find the center of the arc and the tangent position of the corresponding lines, line and arc, and arcs respectively.
3）Requirements 要求 Be consistent in drawing different types of curve segments. The drawing should be
produced with smooth connection between elements with tidy lettering and clean drawing.
标注时要注意符号斜线方向与锥度方向一致。
Example: Drawing of taper 1∶7 ( H = 30 mm, = 40 mm ).
已知 H = 30 mm, = 40 mm, 求作锥度为 1∶7的图形。
1∶7
请点击鼠标左键显示后面内容
40 70
Arc connection 圆弧连接
2) Given the distance across corners, draw a regular polygon (n = 7).
已知其外接圆直径,作正多边形（n =7）。
请点击标题显示其内容
Slope and taper 斜度和锥度
3
1∶ n
1.Slope 斜度
H
slope (斜度)= tanα= H / L
在A4图纸上,按2:1 的比例画出下面图形,粗实线宽度 为0.8mm，尺寸数字为3.5号。 （画图方法）
Title block (标题栏)
本章结束
谢谢您的认真学习！
前一页
退出
Equilateral polygon 正多边形
12
1) Construct regular hexagon (DIA 40mm=A/C of HEX).
同类图线粗细浓淡一致, 连接光滑, 字体工整, 图面整洁。
请点击鼠标左键显示后面内容
10
Exercise 练习题
Mark the following drawing on A4 sheet , scale 2:1， continues thick line 0.8mm，dimension size 3.5.
accurate, clear and clean.
图线细淡、准确、清晰，图面整洁。
请点击鼠标左键显示后面内容
9
Techniques for drawing 2D objects 平面图形的画法
（3） Finalizing the drawing 加深描粗
1） Before producing the final drawing, one should check the sketches carefully, correct all mistakes, and erase all unnecessary curve segments. 加深描粗前，要检查底稿，修正错误，擦去多余图线。
Example: 1. Acute angle 锐角 2.Obtuse angle 钝角
3.Right angle 直角
2. Arc connection between two pieces of arcs. 用圆弧连接两个已知圆弧。
Example: 1.Externally 外切
2.Internally 内切
draw all known curve segments, then intermediate segments, and finally draw connection segments.
画作图基准线确定图形位置,依次画出已知线段和连接线段。
2）Requirements 要求 Use extra thin lines and the sketches should be
(1)
画法二 (2)
60°
相切
Step off the radius round it to give six equally spaced points,Join these points to form the hexagon.
以外接圆半径R 等分圆周为6 点,连
接各点即得正六边形。
Draw tangents to this circle with a 60° set square to produce the hexagon. 画出内接圆,用60°三角板画正六边形
3. Arc connection between one line and another piece of arc. 用圆弧连接已知直线和已知圆弧。
Example:
1.Externally 外切
2. Internally 内切
请点击鼠标左键显示后面内容
7
Techniques for drawing 2D objects 平面图形的画法
画出图框和标题栏。
请点击鼠标左键显示后面内容
8
Techniques for drawing 2D objects 平面图形的画法
（2） Rough sketches 绘制底稿
1）Procedure for rough sketches 画底稿步骤 First draw datum lines for drawing positioning, then
General drawing procedures 绘图的一般步骤 （1）Preparation 准备工作
1) Analysis dimensions and curve segments and plan for the drawing procedures.
分析图形的线段及分析尺寸，拟定作图步骤。
2. Taper 锥度
1∶n
taper(锥度)=2 tan(/2)=H /L=(H-d)/
The taper symbol (符号): 30
1∶n
L
When dimensioning, the orientation of the taper symbol should be in accordance with the orientation of the actual cone.
先粗后细：先加深全部粗实线, 再加深全部虚线、点画线及细实线等。
②First curved then straight: One should first produce curved segments and then straight lines. 先曲后直：描粗加深同一种线型时, 应先画圆弧, 后画直线。 ③Draw parallel lines from top downwards, then vertical lines from left to right, and finally inclined lines. 从上而下画水平线, 从左至右画垂直线, 最后画斜线。 ④Dimension. 标注尺寸。 ⑤Check and fill in the title box. 校对, 填写标题栏。
2）The procedure is as follows 加深描粗步骤 ①First thick lines and then thin lines: One should first draw continuous thick lines, then draw dashed thin lines, long dashed dotted thin lines and continuous thin lines.
Equilateral polygon 正多边形
2
1. Regular hexagons 正六边形的画法
1) Construct regular hexagon (DIA 40mm=A/C of HEX).
作正六边形(其外接圆直径d 为40 mm=正六边形对角距)。
2) Construct two regular hexagons (DIA 40mm=A/C or A/F of HEX