2 ratio
3 graphic lines
4-size
The basic requirements are as follows:
1 title bar
Specify the content, format and size of the title bar. The text direction of the title bar should be the direction of looking at the picture. The outline of the title bar is a thick solid line, and the inside is a thin solid line. The right and bottom lines of the title bar should coincide with the border lines.
2 ratio
Proportion is the ratio of the linear dimensions of the corresponding elements in a figure and an object. When the pattern needs to be drawn in proportion, the appropriate proportion should be selected from the specified series.
In order to get the realism of the physical dimensions from the drawings, the original scale (1: 1) should be adopted as far as possible. When the parts are too large or too small, you can choose the reduction or enlargement ratio specified in the table, but the actual size must be indicated when dimensioning. Generally speaking, all views of the same part should be drawn at the same scale and filled in the title bar. When a view needs to adopt a different scale, the scale can be marked below or to the right of the view name.
3 graphic lines
1. Types of line drawing and its application
GB/T 17450- 1998 "Technical Drawing Lines" stipulates 15 basic line types, and each basic line type has four variants. The width of graphic lines (represented by D) can be divided into three types: thick line, medium thick line and thin line, and the proportional relationship is 4:2: 1. Two kinds of line widths are often used in mechanical patterns. Three line widths can be used in architectural drawings. The line widths of all line types should be selected according to the type and size of the pattern: 0. 18, 0.25, 0.35, 0.5, 0.7, 1, 1.4, 2mm. Drawing lines with a width of 0. 18mm are often unclear in pattern reproduction, so try not to use them.
In mechanical drawing, there are still eight line types specified in GB4457.4-84: thick solid line, thin solid line, wavy line, double broken line, dashed line, thick dashed line, thin dashed line and double dashed line.
2. The drawing method of drawing lines
(1) The widths of similar lines in the same drawing should be basically the same, and the lengths and intervals of dotted lines, dotted lines and double dotted lines should be roughly equal, which should be symmetrical and coordinated in the drawing.
(2) When drawing a dotted line, the first and second ends and the intersection point should be line segments instead of short strokes, which are 2 ~ 5 mm beyond the outline of the figure. When it is difficult to draw dotted lines and dotted lines on smaller figures, thin solid lines can be used instead.
(3) When the dashed line intersects with the dashed line, or intersects with other drawing lines, it should intersect with the line segment. When the dotted line is an extension of the solid line, there should be a gap to represent the dividing line between two different lines.
4-size
(1) The dimension (unit: mm) in the drawing does not need to indicate the code or name of the unit of measurement. If other units are used, the corresponding measurement unit or name must be indicated. 1. dimension line and dimension line are drawn with thin solid lines, which are generally the extension lines of the contour line, axis or symmetrical center line of the figure, which are about 2 ~ 3 mm beyond dimension line. You can also directly use the contour line, axis or symmetrical center line as the dimension boundary. Extension lines are usually perpendicular to dimension line and can be tilted if necessary.
(2) dimension line and dimension line draw with thin solid lines, which must be drawn separately and cannot be replaced by other lines. Generally, they should not overlap with other lines or be drawn on their extension lines. And should try to avoid the intersection between dimension line and dimension line and the extension line. Dimension line should be parallel to the marked line segment, and the dimension line spacing marked in parallel should be uniform, and the spacing should be greater than 5mm, and the dimension line spacing in the same drawing should be equal.
When marking the angle, dimension line should be drawn as an arc with the center of the circle as the vertex of the angle.
(3) dimension line terminal dimension line terminal has two forms, arrow or diagonal. As shown in figure 1-9. Arrows are suitable for various patterns. When the dimension line terminal is in the form of thin diagonal, the dimension line must be perpendicular to the extension line. Only one dimension line terminal can be used in the same drawing. When using arrows, dots or diagonal lines are allowed to be used instead when the position is not enough.
(4) Size Number The number of linear size is generally written above dimension line or at the breakpoint of dimension line. No drawing line can pass the dimension number, otherwise the drawing line should be disconnected.