Extended data
Some parts or nodes with special shapes, holes or complex connections can be moved out of the detailed drawing when it is not convenient to express them clearly in the overall drawing. Section views are mainly used to express the cross-sectional shapes of common object structures, such as ribs, spokes, profiles, shafts with holes, holes, grooves, etc. ; Compared with sectional view, sectional view is simpler in expressing these structures.
The profile is symmetrical, but it is not arranged on the extension line of the cutting symbol, and the projection direction line can be omitted; The cross-sectional view is asymmetric, but it is arranged on the extension line of the cutting symbol, and the letters can be omitted; The cross-sectional figure is symmetrically arranged on the extension line of the cross-sectional symbol, and all marks can be omitted; If the cutting plane passes through the axis of the hole or pit formed by the revolution surface, these structures are drawn according to the cutting plane.
When the section plane passes through the non-original hole, it will lead to two completely separated sections, and these structures should be drawn according to the section drawing; When the cross section is symmetrical, you can draw a cross section at the interruption of the view; Remove the section by cutting two or more intersecting planes, and the middle of the section should be broken; The sectional view drawn in the view is the overlapping sectional Tu Tu. The contour lines of overlapping sections are drawn with thin solid lines.
When the contour lines in the view overlap with the figures in the overlapping cross-sectional view, the contour lines in the view should still be drawn continuously without interruption; Symmetrical overlapping parts do not need to be marked; Asymmetric overlapping parts need to be marked with cutting symbols and projection directions.
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