今天我们学习《机械制图》——机件的常用表达方法第一部分的内容。今天的主要内容是视图。Today we study "Mechanical Drawing" - the first part of the common methods of expression of machine parts. Today's main content is the view.
No.1 基本视图
视图通常有基本视图，向视图，局部视图和斜视图，按需选用。
1.对于形状比较复杂的机件，用两个或三个视图尚不能完整，清楚地表达它们的内外形状时，可如图所示，在原有三个投影面的基础上，再增设三个投影面 ，组成一个正六面体，这六个投影面称为基本投影面。
2.基本视图：机件向基本投影面投影所得的视图，称为基本视图。右视图：由右向左投影所得的；仰视图：由下向上投影所得的；后视图：由后向前投影所得。
3.在表达机件的图样时，不必六个基本视图都画，在明确表示机件的情况下，应使视图的数量最少。
4.用视图表达机件的步骤：首先，按自然位置安放这个机件；然后，选定能表示该机件信息量最多的视图为主视图；最后，再确定使用哪些视图，使能完整清晰的表达这个机件。（尽量避免使用虚线表示机件的轮廓及棱线，避免不必要的细节重复。）
The view usually has a basic view, to the view, partial view and oblique view, according to the need to choose.
1. For the complex shape of the machine, with two or three views can not be complete, clearly express their internal and external shape, as shown in the figure, on the basis of the original three projection surface, and then add three projection surface, composed of a positive hexahedron, the six projection surface is called the basic projection surface.
2. Basic view: The view obtained by projecting the machine to the basic projection plane is called the basic view. Right view: from the right to the left projection; elevation view: from the bottom up projection; rear view: from the back to the front projection.
3. When expressing the drawing of the machine, it is not necessary to draw all six basic views, and the number of views should be kept to a minimum in the case of a clear representation of the machine.
4. Steps to express the machine in view: first, place the machine in its natural position; then, select the view that represents the most information about the machine as the main view; finally, determine which views to use, so that the machine can be expressed completely and clearly. (Try to avoid using dotted lines to indicate the outline and prism of the machine to avoid unnecessary repetition of details.)
No.2向视图和局部视图
向视图
向视图是可自由配置的视图。若一个机件的基本视图不按基本视图的规定配置，或不能画在同一张图纸上，则可画向视图，此时，应在视图上方标注大写拉丁字母"x"，称为x向视图，在相应的视图附近用箭头指明投射方向，并注写相同的字母。
局部视图
局部视图是将物体的某一部分向基本投影面投射所得的视图。局部视图可按基本视图的配置形式配置，也可按向视图的配置形式配置并标注。
Orientation view
The directional view is a freely configurable view. If the basic view of a machine is not configured according to the provisions of the basic view, or can not be drawn on the same drawing, it can be drawn to the view, at this time, the view should be marked above the capital Latin letter "x", called x to the view, in the corresponding view near the arrow indicating the direction of projection, and write the same letter.
Local view
The local view is a view of a part of the object projected to the basic projection plane. The local view can be configured in the form of a basic view or in the form of a directional view and labeled.
No.3斜视图
机件向不平行于基本投影面的平面投影所得的视图称为斜视图。斜视图通常按向视图的配置形式配置并标注，如图，必要时，可将斜视图旋转配置，这时，图名应加旋转符号，表示该视图名称的大写拉丁字母”x“应靠近旋转符号的箭头端，也允许将旋转角度标注在字母之后。
The view obtained by projecting the machine to a plane not parallel to the basic projection plane is called oblique view. Oblique view is usually configured and labeled in the form of the configuration to the view, as shown in the figure, if necessary, the oblique view can be rotated configuration, when the name of the figure should be added to the rotation symbol, indicating that the view name of the capital Latin letter "x" should be near the arrow end of the rotation symbol, also allows the rotation angle marked after the letter.
参考资料：文字：百度；图片：微博；翻译：百度翻译
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