Mechanical Drawing

This is a mind map about mechanical drawing. Mechanical drawing is a discipline that uses drawings to accurately represent the structural shape, size, working principle and technical requirements of machinery. Drawings are composed of graphics, symbols, text and numbers. They are technical documents that express design intentions and manufacturing requirements and communicate experience. They are often called the language of the engineering community. The following is a detailed introduction to mechanical drawing

Edited at 2024-12-13 15:56:09

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Mechanical Drawing

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Outline

Mechanical Drawing

Drawing format

B represents the short side, L represents the long side and L=√2B. If necessary, an extended format is allowed, and the size is increased by an integer multiple of the short side of the basic format size.

frame style

Picture frame with binding edges

Generally, A3 format is used for horizontal mounting and A4 format is used for vertical mounting.

The frame line is drawn with a thick solid line. The area between the frame line and the paper boundary line indicating the size of the frame is called the perimeter.

Picture frame without binding edges

Additional symbols can be drawn on the drawing frame and around the drawing as required, such as centering symbols, direction symbols, shearing symbols, etc.

Title block and details column

The title block is located in the lower right corner of the drawing, and its outer frame is drawn with a thick solid line. The title block can be simplified in school assignments.

The details bar describes the quantity and materials of various components that make up the assembly. The details bar is located above the title bar. If there is not enough space, it can be continued from bottom to top on the left side of the title bar.

Proportion

The ratio of the linear size of the graphics in the picture to the corresponding elements of the object. If the ratio is greater than 1, it is an enlarged size, and vice versa, it is smaller than the size.

Figures on the same paper generally use the same proportions

font

Fonts need to be: neat, evenly spaced, clear strokes, neatly arranged

Font height size (mm): 1.8, 2.5, 3.5, 5, 7, 10, 14, 20. If the font is enlarged, it will increase according to the ratio of √2

The font adopts long imitation Song style and adopts simplified Chinese characters officially announced by the state (the minimum height is not less than 3.5mm, and the character width is approximately 0.7 times the height

Latin letters are generally in italics

Numbers generally use Arabic numerals, and Roman letters may be used in partially enlarged labels.

Drawing lines and how to draw them

Linear

4 basic linear

Thick solid line: used to outline visible contours and is the most important line type.

Thin solid line: used for dimension lines, extension lines, internal structure lines, etc.

Dashed lines: represent invisible contours and indicate internal or backside structures.

Dotted line: often used for centerline, axis or line of symmetry

Basically linear deformation - wavy lines: represents breaks or uncertain boundaries, especially suitable for showing partial truncation of objects

Graph line combination - double polyline: boundary line at break

Drawing method

The width of the graph should be kept consistent. The width in mm includes: 0.13, 0.18, 0.25, 0.35, 0.5, 0.7, 1, 1.4, 2. Generally, 0.5, 0.7 is used

The ratio between thick and thin lines is 2:1

I) When drawing the symmetrical center line of a circle (a dotted line), the center of the circle should be the intersection point of the long drawing, and it cannot intersect at points or intervals. Both ends of the dotted line should exceed the arc or the corresponding graphic outline by 3 to 5mm. If the graphic is smaller, it can be replaced by a thin solid line. 2) When the graph line is short, it can be replaced by a thin solid line. 3) When the dotted line, dotted line and other graph lines intersect, they should intersect at the line segment. When the dotted line is an extension of the solid line, there should be a gap between the dotted line and the thick solid line.

Dimensions

Dimension components: dimension numbers, dimension lines, dimension lines, terminals of dimension lines

Dimension lines and extension lines are drawn with thin solid lines. Dimension lines are independent lines and cannot be replaced by other lines or coincide with other lines.

There are two types of terminals for dimension lines: arrows and slashes. Mechanical drawings mostly use arrows. If the position is not enough, dots and slashes are allowed to be used instead.

1. Uniqueness: Each dimension is marked only once, and there should be no repeated markings to avoid confusion.

2. Completeness: All necessary dimensions must be marked to ensure that the manufacturer can produce the part exactly according to the drawing.

3. Clarity: Dimension numbers, symbols and guide lines should be clear and avoid overlapping with other graphics or text.

4. Reasonability: Choose an appropriate labeling method so that the dimensions are comprehensive but not too dense, affecting reading.

5. Coordination: Dimensional units should be unified throughout the drawing, generally using the metric system