2. Form of Projection 投影的形成 投影的形成 Types of Projection 投影法分类 投影法分类 Features of Orthographic Projection 正投影特性 正投影特性 Three-view of Component 物体的三视图 物体的三视图 Exercises 练习题 练习题 Principles of Orthographic Projection 正 投 影 法 原 理 请点击相应标题显示其内容

3. 2 Center of projection Center of projection Plane of projection Object Object Lines of projection Projection Projection Form of Projection 投影的形成 Form of Projection 投影的形成 Projection method : When the line of projection passes through the object and the pre - established plane, there will be graphics object and the pre - established plane, there will be graphics produced on the plane. This method is called projection. produced on the plane. This method is called projection. 投影法： 投影法是投射线通过物体，向选定的平面投射， 投影法： 投影法是投射线通过物体，向选定的平面投射， 并在该面上得到图形的方法。 并在该面上得到图形的方法。 请点击鼠标左键显示后面内容

4. 3 Types of Projection 投影法分类 Types of Projection 投影法分类 Projection method 投影法 Central projection method 中心投影法 Central projection method 中心投影法 ( The central projection is mainly used for the pictorial ( The central projection is mainly used for the pictorial drawings of buildings. 一般多用于建筑图样 ) drawings of buildings. 一般多用于建筑图样 ) Parallel projection method 平行投影法 Parallel projection method 平行投影法 ( It is used in most engineering drawings. ( It is used in most engineering drawings. 广泛用于机械、电子、化工等行业的图样 ) 广泛用于机械、电子、化工等行业的图样 )请点击鼠标左键显示后面内容

5. 4 3. Homophyly: When planar features or lines are inclined to the 类似性 projection plane in general, the projection produces 类似性 projection plane in general, the projection produces similar shapes of the original feature. The length of similar shapes of the original feature. The length of projected lines will be shorter than the real length. projected lines will be shorter than the real length. 当图形或直线倾斜于投影面时，图形的投影成类似形, 线 当图形或直线倾斜于投影面时，图形的投影成类似形, 线 段的投影长度比实长短。 段的投影长度比实长短。 2. Accumulation: When planar features or lines are orthogonal to the 积聚性 projection plane, the projection accumulates to a 积聚性 projection plane, the projection accumulates to a line or a point. line or a point. 当图形或直线垂直于投影面时, 其投影积聚成一直线或点。 当图形或直线垂直于投影面时, 其投影积聚成一直线或点。 1. Authenticity: When planar features or lines are in parallel with the 真实性 projection plane, the projection shows the real shape 真实性 projection plane, the projection shows the real shape or true length of the features being projected. or true length of the features being projected. 当平面图形或直线平行于投影面时, 其投影反映实形或实长。 当平面图形或直线平行于投影面时, 其投影反映实形或实长。 Features of Orthographic Projection 正投影特性 Features of Orthographic Projection 正投影特性 请点击鼠标左键显示后面内容

6. 5 1.Form of three-view drawings 1. Form of three-view drawings 三视图的形成 三视图的形成 Three-View of Component 物体的三视图 Three-View of Component 物体的三视图 请点击鼠标左键显示后面内容 Single orthographic projection单面正投影 A plan of an object is not always sufficient to describe it completely. 仅有物体的一个投影不能确定 它的空间形状。 Additional orthographic views can be drawn to sufficiently describe an object. It is necessary to use multiple views in engineering drawings. 为了确定物体的空间形状, 需要增加投影面。故在工程图样中 多采用多面视图。 为了确定物体的空间形状, 需要增加投影面。故在工程图样中 多采用多面视图。

7. 6 These axes meet at a point which is called the origin. which is called the origin. 三投影轴垂直相交于原点 O. 三投影轴垂直相交于原点 O. Y -axis → Y 轴 Three-View of Component 物体的三视图 Three-View of Component 物体的三视图 请点击鼠标左键显示后面内容 1) Set up three-view projection system 建立三面投影体系 建立三面投影体系 The three projection planes are orthogonal from each other. Make up of one projection system. 采用三个相互垂直的投影面, 构成投影体系。 V -plane → V ertical plane 正 ( 垂直 ) 平面 H -plane → H orizontal plane 水平面 W -plane → W all(Auxiliary vertical) plane 侧 ( 辅助垂直 ) 平面 The intersection lines of the three projection planes are called the axes of projection. 三投影面的交线为投影轴 三投影面的交线为投影轴 X -axis → X 轴 Z-axis → Z 轴

8. 7 To draw three-view drawings on a drawing sheet 将三投影面展成一个平面 The V -Plane is first fixed. V 面不动 V 面不动 The H -Plane turns down 90 . The H -Plane turns down 90 . H 面向下转 90 , Y 轴记为 Y H, H 面向下转 90 , Y 轴记为 Y H, The W -Plane turns right 90 . The W -Plane turns right 90 . W 面向右转 90 , Y 轴记为 Y W 。 The drawing produced on the profile projection plane ( W -Plane). 由左向右观察将物体向 W 面投影而得到的视图。 画三视图 2) Draw three views 画三视图 Front view 主视图 主视图 ： Top view 俯视图 : The drawing produced on the frontal plane ( V -Plane). 由前向后观察将物体向 V 面投影而得到的视图； The drawing produced on the horizontal projection plane ( H -Plane) 由上向下观察将物体向 H 面投影而得到的视图； Llft view 左视图 : 请点击鼠标左键显示后面内容 Three-View of Component 物体的三视图 Three-View of Component 物体的三视图

9. 8 2. View positions and rules for producing three-view drawings 三视图的位置关系和投影规律 1 ) Positions 位置关系 2 ) Rules 投影规律 45° The height of the front view and the left-side view should be aligned and is equal. 主、侧视图高平齐； The width of the top view and the left-side view should also be aligned and is equal. 俯、侧视图宽相等。 The length of the front view and the top view should be aligned and is equal. 主、俯视图长对正； 请点击鼠标左键显示后面内容 Three-View of Component 物体的三视图 Three-View of Component 物体的三视图 Front view 主视图 Left-side view 侧视图 Length align 长对正 长对正 Height align 高平齐 Width equality 宽相等 Top view 俯视图

10. 9 ( 图线有重合时的优先顺序为：粗实线、虚线、细点 画线、双点画线、细实线 ) 图线有重合时的优先顺序 1) Define the scale, select the size of drawing sheet. 确定图幅和比例； 2) Choose a direction for front view projection. 确定主视图的观察方向； ( 使其主要表面平行或垂直于投影面, 能表达更多的结构形状 ) 3)Draw the datum line, noticing that each view is in proper distance. 布置各视图的位置； 布置各视图的位置； 4) Project the object from three different directions and draw the corresponding views. 按照三等规律画其三视图； the corresponding views. 按照三等规律画其三视图； 5) Check and correct, erase all unnecessary lines. 校核有无错漏，擦去多余线条； 校核有无错漏，擦去多余线条； 6) Draw deeply according to the demand. 按标准图线加深视图。 按标准图线加深视图。 ( 画出基准线、对称中心线、轴线） ( 加深顺序为：圆形、圆弧、水平线、垂直线、斜线 ) ( 可见轮廓线画粗实线，不可见轮廓线画虚线 ) 请点击鼠标左键显示后面内容 Three-View of Component 物体的三视图 Three-View of Component 物体的三视图 3. Steps for producing three-view drawings. 画物体三视图步骤

11. 10 请点击鼠标左键显示后面内容 view Plan or top view Front view Left view Draw three views according to pictorial drawing. 1. Draw three views according to pictorial drawing. 根据立体图画出主、俯、左三个视图。 由于投影面的大小与视图 无关。因此, 在画三视图时, 不必画出投影面的边框。

12. 11 练习题 Exercises 练习题 1. Find out the right three views for each pictorial 1. Find out the right three views for each pictorial drawing, and make out the right number in bracket. drawing, and make out the right number in bracket. 找出与立体图相对应的三视图，并在括号内填写相应编号。 找出与立体图相对应的三视图，并在括号内填写相应编号。 2. Draw three views according to pictorial drawing ( the front view is looked from S). 2. Draw three views according to pictorial drawing ( the front view is looked from S). 根据立体图 ( 所给主视图观察方向 S ) ，画出相应的三视图。 根据立体图 ( 所给主视图观察方向 S ) ，画出相应的三视图。 3. Draw three views according to pictorial drawing ( the front view is looked from S). 3. Draw three views according to pictorial drawing ( the front view is looked from S). 根据立体图 ( 所给主视图观察方向 S ) ，画出相应的三视图。 根据立体图 ( 所给主视图观察方向 S ) ，画出相应的三视图。请点击相应题目显示其内容

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14. 13 S （ Sight or center of projection of projection 投射中心 ） Central projection ： When the lines of projection meet at a point, it is called central projection. it is called central projection. 中心投影法 : 投射线汇交于一点的投影法称为中心投影法 。 中心投影法 : 投射线汇交于一点的投影法称为中心投影法 。 请点击鼠标左键显示后面内容 Central projection method 中心投影法 Projection lines （ 投射线 ） Object ( 物体 ) Object ( 物体 ) P Projection plane ( 投影面 ) P Projection plane ( 投影面 ) Projection Projection ( 投影 )

15. 14 Lines of projection will be parallel ( 投射线平行 ) 空间物体用大 写字母表示。 投影用小写 字母表示。 Parallel projection: When the lines of projection are parallel with each other, it is called parallel projection. each other, it is called parallel projection. 平行投影法 投射线互相平行的投影法称为平行投影法。 平行投影法 投射线互相平行的投影法称为平行投影法。 请点击鼠标左键显示后面内容 Parallel projection method 平行投影法 Object ( 物体 ) P Projection plane ( 投影面 ) P Projection plane ( 投影面 ) Projection Projection ( 投影 ) S

16. 15 ( 一般作为辅助图样 ) Axonometric projection Axonometric projection 轴测图 轴测图 Parallel Projection method 平行投影法 ( 光线 S  P 投影面 ) Oblique projection method Oblique projection method斜投影法 Orthogonal projection Orthogonal projection 正投影图 ( 作为正式的工程图样 ) Orthographic projection method 正投影法 正投影法 ( 光线 S  P 投影面 ) p s s 请点击鼠标左键显示后面内容 90 °  90 ° S S

17. 16 Orthogonal projection 正投影图 正投影图准确, 真实, 作 图简单, 但立体感不强。

18. 17 Axonometric projection 轴测图 轴测图立体感强, 但作图较复杂

19. 18 Priority of coinciding lines 图线重合时的优先顺序 图线有重合时的优先顺序为：粗实线、虚线、细点画线、双点画线、细实线。

20. 19 1. Find out the right three views for each pictorial drawing, 1. Find out the right three views for each pictorial drawing, and make out the right number in each bracket. and make out the right number in each bracket. 找出与立体图相对应的三视 图，并在括号内填写相应编号。 找出与立体图相对应的三视 图，并在括号内填写相应编号。 请点击解答显示其内容 1 2 3 4 5 6 7 8 9 10 11 12

21. 20 Draw three views according to pictorial drawing ( the 2. Draw three views according to pictorial drawing ( the front view is looked from S). front view is looked from S). 根据立体图 ( 所给主视图观察方向 S ) ，画出相应的三视图。 根据立体图 ( 所给主视图观察方向 S ) ，画出相应的三视图。 S 请点击解答显示其内容

22. 21 Draw three views according to pictorial drawing ( the 3. Draw three views according to pictorial drawing ( the front view is looked from S). front view is looked from S). 根据立体图 ( 所给主视图观察方向 S ) ，画出相应的三视图。 根据立体图 ( 所给主视图观察方向 S ) ，画出相应的三视图。 请点击解答显示其内容 S

23. 22 在图片上点击鼠标左键可以 “ 暂停 ” 或再次 “ 播放 ”

24. 23 在图片上点击鼠标左键可以 “ 暂停 ” 或再次 “ 播放 ”

25. 24 在图片上点击鼠标左键可以 “ 暂停 ” 或再次 “ 播放 ”

26. 25 在图片上点击鼠标左键可以 “ 暂停 ” 或再次 “ 播放 ”