Mechanical design starts with drawing the simplest parts diagram. For example, surveying and mapping a simple component, helping others to disassemble and draw a part drawing from the component drawing, etc., these are the stages that a novice must go through. However, even a simple part drawing is full of errors: or the dimensions are not complete, or the tolerances are not suitable, or there is a closed dimension chain, or the technical requirements are wrong, etc. Therefore, the machinery industry has always required long-term accumulation and learning. The foundation is very important when a tall building starts from the ground, let us start by drawing a part diagram!
A drawing that expresses a part is called a part drawing. It is the basis for manufacturing and inspecting parts, the basis for the craft department to make the process route, and the basis for the quality inspection department to inspect.
1 Contents of parts drawing
The first thing we should know is what should be included in a complete part drawing.
(1) Graphics: Use a set of views (including views, section views, section views, etc.) to express the structural shape of the part completely, clearly and simply.
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(2) Dimensions: Use a set of dimensions to completely, clearly and reasonably mark the structural shape of the parts and the size of their mutual positions.
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(3) Technical requirements: Use some specified symbols and words to concisely give the technical requirements that parts should meet during manufacturing, inspection and use. Including roughness, dimensional tolerance, shape tolerance, datum symbol, technical requirements, etc.
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(4) Title block: use the title block to fill in the name of the part, material, proportion of the drawing, the name and date of the drafter and checker, etc. (The title block used in this figure is a simplified version, and only the full version is used in the project).
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2 Part structure analysis method
Anyone who is engaged in the design industry starts with imitation. Imitate other people's appearance, learn their design ideas, and constantly accumulate experience. The structural analysis of parts is to analyze the functions of different structures of parts based on design requirements and process requirements. We not only need to know what the part looks like (simple surveying and mapping), but also why it is designed in this way (design thinking), so that we can improve our design thinking instead of blindly imitating it.
(1) From the perspective of design requirements, parts in the machine can perform functions such as support, accommodation, transmission, coordination, connection, installation and positioning, which are the basis for determining the main structure of the parts.
(2) From the perspective of process requirements, in order to make the blank manufacturing, processing, measurement, assembly and adjustment of parts smooth and convenient, structures such as rounded corners, draft angles, and chamfers should be designed. Basis for the structure.
(3) From the perspective of practicality and aesthetics, not only is the product required to be usable, but it is also required to be economical and aesthetically pleasing, and the structural shape must be considered from an aesthetic point of view.
3 Example 1 of part structure analysis
The figure below shows the driven shaft of a reducer. Its main function is to install in the bearing, support the gear to transmit torque, and connect with external equipment.
We analyze the role of its various features, as well as design ideas.
4 Example 2 of part structure analysis
The picture below shows the base of a gearbox, which is a more complicated part. We must design a gearbox in the school curriculum design. The role of each feature of the gearbox base is now analyzed.
