装配图的读图和拆画零件图教学教案

Determine how many views are needed (Where to use section or cut view ) 需用几个视图表达 (何处用剖视或断面图)
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Determine the projection direction of the front view 确定主视图观察方向
弄清各个零、部件的作用和它们之间的相对位置、装配关系 、连接和固定方式，以及拆装顺序等；
3) Read the structural shape of each part. 看懂各零件的结构形状。
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Methods and Steps 读图的方法和步骤
1. Understanding briefly 概括了解
2. 拆画零件图的方法和步骤
In order to separate an assembly drawing, one must first understand the assembly drawing. The method and steps to separate the drawing following summarizes are as
1）The name, purpose, and specification 了解机器或部件的名称、用途和规格
2）Understand the composition of the machine or subassembly.
了解机器或部件的组成。
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Let us take the ball valve in Fig. 9-2 for example to explain the methods and steps for reading and interpreting an assembly drawing.
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Detail drawings from assembly drawings 由装配图拆画零件图
(3) Refining the structures of the parts 补全零件的结构
Refine the part drawings with what is omitted in the assembly drawing, such as chamfer, escape, and round. 补齐该零件在装配图中缺少 的结构以及省略的结构，如：倒角、退刀槽、小圆角等。
在以上各步骤的基础上，结合尺寸标注及技术要求等有关 内容，进一步综合分析总体结构、传动关系和工作原理，通 过归纳总结，想象出装配体的总体结构形状。
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Detail drawings from assembly drawings 由装配图拆画零件图
1. Method and steps for separating the assembly drawing
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Objectives and requirements 读图的目的和要求
Three items should be stressed for the objectives and requirements of reading assembly drawings 读装配图的目的和要求,主要有以下三点：
现以“球阀”为例，说明读装配图的方法和步骤 。
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Methods and Steps 读图的方法和步骤
3. Imaging the structural shape 想象结构形状
By combining dimensioning and technical requirements, further analyze the structure, transmission relations and working principles, create an image of the assembly structure.
the section line in each view; 根据同一零件的剖面线在各视图中一
致的特点, 将该零件与其他零件区分开来；
3) According to the third-alignment rule and analysis of lines and
faces, determine the structural shape of the part.. 根据三等规律和
线面分析法，研究确定该零件的结构形状。
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Detail drawings from assembly drawings 由装配图拆画零件图
(2) Determiniቤተ መጻሕፍቲ ባይዱg the representation 确定其表达方案
Analyze what type the part belongs to 分析属哪类零件
1) Understand the performance, function and working principles of the machine or subassembly.
了解机器或部件的性能、功用和工作原理；
2) Clarify the purpose, the relative position, the fitting relationship of each part, the methods of how to connect and fix them, and sequence for disassembly.
follows 拆图是在看懂装配图的基础上进行的, 其方法和步骤如下：
(1) Separating the key parts 分离出关键零件
1) Locate the parts according to its name and item block; 根据零件
名称和明细栏找出其在图中的位置；
2) Separate the part from others, according to the consistence of