Engineering drawing is an important process in engineering technology. It is an important basic compulsory course in higher engineering courses. Welcome to check the analytical engineering drawings and tolerance coordination I have compiled below!
1, thick line width b should be selected between 0.5 and 2mm according to the size and complexity of the drawing, and the recommended series are: 0.25, 0.35, 0.5, 0.7, 1,1.4,2mm..
2. Reduction ratio (recommended): 1:2, 1:5,1:1:2x 10 n,1:5x/kloc.
3. The new standard stipulates that the text direction in the title bar is the direction of looking at the picture.
4. China is represented by the first perspective view, and the rear view is arranged on the right side of the left view. Countries such as Europe and America adopt the third perspective representation.
5. An engineering drawing generally contains three basic contents: title bar, basic view and technical requirements.
6. In the assembly drawing, the section lines of two adjacent metal parts are in opposite directions or in the same direction but at different intervals, and the section lines of the same part are still in the same direction in all views.
7. When cross-section lines are replaced by coloring, coloring can only be used for part drawings, but not for assembly drawings.
8. For the section with narrow area, when the width. When the figure is less than or equal to 2mm, the section line can be blacked out instead.
9. When the connection of internal and external threads is represented by sectional view, the tightened part shall be drawn according to the external thread diagram.
10, the end of spline working length and the end of tail length are drawn with thin solid lines.
1 1. When the number of effective turns of the spring is more than 4, the drawing method of omitting the middle part can be adopted, but three dotted lines representing the spring axis and the center line of the steel wire section should still be drawn.
12, does the spring draw to the right or to the left, and does it rotate? Left? The text must be marked.
13. Spiral springs, disc springs and leaf springs with spring profiles equal to or less than 2mm in diameter or thickness are allowed to be drawn by schematic diagrams.
14, schematic diagram is often used to express the main structural principle characteristics of the process system in mechanical manufacturing.
15. Marking dimension line: When arrows are used and the position is not enough, dots or diagonal lines are allowed to be used instead.
16. The size mark should be avoided within 30 degrees from the vertical. When it is unavoidable, a horizontal mark with a guide line can be used.
17. When marking slope and taper, the direction of symbols should be consistent with the direction of slope and taper.
18. When marking the thickness of plate-shaped parts, can you add a symbol before the size number? t？ .
19, dimensional tolerance: it is the allowable dimensional variation, that is, the tolerance zone.
20. Cooperation: refers to the assembly standard and state of two parts.
2 1, and the standard tolerance grade is 0 1, 0, 1, 2? , 18***20.
22. In coordinate marking, the numerator is the tolerance zone of the hole and the denominator is the tolerance zone of the shaft.
23. Shape tolerance: The total allowable deviation of the shape of a single actual element of a part is called shape tolerance;
Position tolerance: the total allowable deviation of the position of the associated actual component from the benchmark is called position tolerance;
Form and position tolerance is called form and position tolerance for short.
24. The total geometric error of parts surface consists of three parts: surface roughness, surface roughness and shape error.
Surface roughness refers to the micro-geometric error of machining surface wave distance below1mm.
25, in engineering drawing, due to the need of processing, must mark the processing surface quality requirements symbol.
26, the same surface roughness value Ry & gtRz & gtRa, and Ry value is about 8 times of Ra value. Ra value is preferred for marking general surface roughness.
27. Process dimension chain: the dimension chain formed by the related process dimensions of the same part during the processing of parts;
Assembly dimension chain: in the process of machine design and assembly, the dimension chain is formed by the design dimensions of related parts. ;