What Is a Section Line?

A section view, also called a section view, is an example of the internal structure shown by a certain cutting direction on the related graphics. The section view is an imaginary use of a cutting plane to cut the object apart and remove the viewer and the cutting plane The part in between is an orthographic projection of the remaining part to the projection surface. Section drawings are generally used in engineering construction drawings and design of mechanical parts, supplementing and improving design documents. They are detailed designs in engineering construction drawings and mechanical parts design, and are used to guide engineering construction operations and mechanical processing. The section view is a diagrammatic form of imaginarily cutting the ground vertically along a specified direction line and graphically showing the three-dimensional distribution and vertical structure of the drawing pair. ^[1]

[pu miàn tú]

The section view, also known as the section view, is an illustration of the internal structure shown by the relevant figure in a certain cutting direction.

The section view is an imaginary section of the object with a cutting plane, removing the part between the observer and the cutting plane. For the rest

1. Determine the location of the cutting plane

When choosing the cutting plane position, in addition to paying attention to making the cutting plane parallel to the projection plane, it is also necessary to make it pass through the representative position of the shape.

1. In order to make the figure clearer, the dotted line is generally not drawn in the section figure.

2. Because the cross-sectional view is hypothetical, each cut is a cut based on the shape being kept intact.

3. If the material of the body is not specified, a thin solid line (also called a section line) in the same direction, at the same distance, and at 45 ° to the horizontal line should be drawn at the corresponding position. When drawing section lines, the inclination direction and spacing of section lines of the same shape in each section view must be the same. ^[2]

Sectional view

The section is cut completely with a cutting plane, and the resulting section is called a full section.

Sectional view

If the shape is symmetrical, when drawing, half of the shape's projection is often drawn as a cross-sectional view, and the other half is drawn as an outline drawing. This method of drawing can save the number of projection images, and from the same projection image can simultaneously observe the three-dimensional shape and internal structure. ^[2]

When drawing a half-section view, pay attention to:

1. The half-section drawing and half-outline drawing shall be bounded by the symmetry symbol, and the symmetry plane or line shall be drawn as a thin single-dot long dash.

2. When the shape is symmetrical from left to right, draw a half-section view on the right side and the half-outline drawing on the left; when the shape is symmetrical back and forth, draw a half-section view on the front side and a half-out view on the rear side.

3. The cut symbols and figure names of the half-section view and the full-section view are consistent.

Sectional view

It is inconvenient to cut two holes at the same time. Therefore, use two parallel planes to cut through two holes. In this way, two holes that are not in the same direction are reflected at the same time on the same sectional view. This section is cut with two or more cutting planes parallel to each other, and the resulting sectional view is called a stepped sectional view.

It should be noted that, because the cutting plane is imaginary, the contour line generated by the shape due to the cutting at the turning plane of the cutting plane should not be drawn in the cutting diagram. ^[2]

Sectional view

Cut the shape with two intersecting cutting planes. The resulting cross-sectional view is developed by rotation and parallel to a basic

1-1 stairs section

Orthographic projection after projection is called a developed sectional view.

1-1 The sectional view of the staircase, because the two steps of the staircase form a certain angle on the horizontal projection, such as using one or two parallel cutting planes, the staircase cannot be clearly expressed. Therefore, you can use two intersecting cutting planes to cut, remove the part between the cutting plane and the observer, and rotate the right part of the remaining stairs to the orthographic projection plane to be parallel. Add the word "Expand" after the name of the figure, and add parentheses.

Section view

Partial sectioning of the shape to form a partial section is called a partial section view.

When drawing a partial section view, pay attention to:

1. Partial section view is delimited by wavy lines without cutting symbols and numbers.

2. The range of the partial section view usually does not exceed 1/2 of the projected figure.

Sectional view

The structure of a wall represented by a layered cross-sectional view is drawn by two wavy lines as the boundary, and the corresponding structure is drawn. ^[2]