In any manufacturing, construction industry for the manufacture of parts, structures use certain images. They represent the appearance of an object from different points of view and sometimes involve the use of a section or section technique.
This approach in engineering graphics is carried out in accordance with certain standards. They clearly specify the types of sections, allowing you to bring this technology to common standards. This allows engineers, workers to correctly understand such images. The quality of the entire production process and the final result of the organization’s work directly depend on this. Therefore, the creation of images put forward special requirements.
Image Execution Standard
Performing schematic images, their sections, various types of sections, cones, beams, applying them to drawings govern various standards. The main one is the Unified Design Documentation System (ESKD) "Images - Views, Sections, Sections."
This GOST was introduced on January 1, 1968. He stipulates that the image is considered as a projection of an object onto a plane at a certain angle. GOST "Images - views, sections, sections" says that there should be a minimum number of such drawings. But thanks to them, the specialist should get complete information about the object.
Therefore, all images, according to their content, GOST divides into types, sections and sections. This document also establishes the types of signs, inscriptions and signs.
GOST 2.305-08 regulates that all images should be applied to the drawing using the technology of orthogonal (rectangular) projection. Ideally, the subject is in the middle between the observer and the project plane.
But in view of the fact that some nodes and elements require consideration from a different angle, this condition is violated. Therefore, the types of sections, the drawings of which are used in the production environment, are called images. For their implementation, the standards regulate a number of simplifications and reductions.
The concept of view, section and section
Sections, sections, views - these are the three main categories in the construction of drawings of engineering graphics. They are different in content. Therefore, they deserve detailed consideration.
A view is a drawing of the surface of a part that is facing the observer. To simplify the work of an engineer, in such a figure it is allowed to indicate invisible surfaces with dashed lines .
The main view is the front image of the part. But there are other varieties of it. The part is also depicted on the left, top, right, back or bottom.
A section is a drawing of a part that has been mentally cut by a plane (one or more). The section will show what is in the plane of the section and beyond it.
But the section is also called such a consideration of the element, in which a plane cut it in a certain way. But the figure shows only what was in this secant plane. What is behind it is not visible in the drawing.
These definitions must be taken into account by a specialist performing technological tasks using engineering graphics.
Remote and superimposed sections
ESKD standard reveals types, sections, sections with the help of a certain classification. According to this approach, it is possible to better understand the assertions of the standards for the implementation of graphic images of parts.
Sections are staked or superimposed. Both of these subspecies are not part of the section.
It is preferable to use remote sections in engineering graphics. They are usually placed in the gap between the constituent elements of the same species.
Such a contour (as well as the image included in the section) is applied by thick lines to the drawing. If the cross section is superimposed, its boundaries are indicated by solid, but thin boundaries.
Dotted lines are used to indicate the axis of symmetry of such images. They are applied thinly and are not indicated by any letters or arrows.
But to indicate the trace of the secant plane, it is necessary to use a thick open line. It is indicated by arrows that make it clear the direction of the gaze.
The dissection plane itself is designated in Russian capital letters. The inscription of the cross-sectional view of wires, nodes or parts is made according to type "AA".
In this case, the final and initial strokes should not cross the contour. Alphabetic letters are assigned without repetition or omission. The font size should be 2 times larger than the numbers indicating the size.
The letters are located relative to the main inscription in parallel. Moreover, this does not depend on how the secant plane is located.
Secant plane position
Depending on the position of the secant plane, there are several varieties of images that are regulated by GOST. Views, sections, sections, according to generally accepted rules, are determined in space relative to the horizontal plane.
Accordingly, the dissecting plane can pass through the object horizontally, vertically or at an angle.
In the first case, the sectional view is considered transversely parallel to the horizontal plane. In many drawings, this type of engineering drawing is called a plan. Such slices may also be called differently in each manufacturing process.
Vertical sections suggest placing the slice perpendicular to the base. And inclined species form a certain angle between the horizontal and secant planes. It is different from direct.
Vertical sections are frontal (parallel to the frontal projection line) or profile (parallel to the profile projection line).
If the slice is directed along the height or length of the object, this is a longitudinal section. But there is another orientation of the drawing. There are types of cross sections that have a perpendicular orientation in the space of the secant plane, relative to the length or height of the object.
In the drawing, the position of the cross section is indicated by arrows and is indicated by an open line.
The number of secant planes
For simple parts, it is enough to use only one section plane. This is enough to understand how a technician should make this part. But for complex workpieces this is not enough. For example, there are types of beam sections that need to be mentally cut in a more complex way.
For this, the standards regulate the use of several secant planes. They can be broken or step. The orientation of the planes plays an important role in this matter.
The angle at which they relate to each other determines the name. If the planes, connecting, form a right angle, this is a stepped cut. When this ratio is characterized by a different slope, the cross section is broken.
With complex sections at the intersection of the planes, strokes are carried out among themselves. On the final and initial of them, arrows are indicated in the direction of the observer's gaze. They are located 2-3 mm from the stroke. Letters are placed near the arrows at the intersection from the position of the outer corner. The slice itself in this case is always marked by type "AA".
Local section
The section is allowed to be performed only in one specific place of the object. This limited consideration of the workpiece device is called local. It can be applied anywhere in the drawing, pointing with an arrow to the associated image area. This is convenient for depicting long, but permanent in cross-sectional shape objects.
Such an image may be limited to the smallest clipping line. Cross-sectional views of wires due to their long lengths can be performed using this approach.
This slice stands out against the background of the image with a solid wavy line. These lines do not coincide with other borders of the drawing.
The local section is indicated on the image by type "A". The type associated with it also indicates the corresponding letter designation.
Additional section
Images (views, sections, sections) can be performed on planes that are not parallel to the main sections of the projections. They are called optional. This approach is used in engineering graphics when it is impossible to show any part of the subject in the main views without distorting the shapes or sizes.
This section is signed by type "A". The object corresponding to the additional sectional view is connected with it by an arrow and signed with a similar letter. The pointer also makes it clear the direction of the observer's gaze.
If an additional slice is located directly on the projection of the corresponding image, the inscription and arrow do not need to be applied to the drawing.
Additional types of sections can be rotated. But the main position of the subject is maintained. An inscription of type “A” also adds a turn sign.
Using this approach avoids hatching the drawing. It makes understanding difficult and degrades image clarity. Because such techniques can improve the quality of graphics.
Symmetry
The types of sections can be arranged in a gap that is formed between parts of the same image. This can be done on the continuation of the cut plane trace. But such an approach is permissible only with a symmetrical figure, which is obtained by dissection. The section is taken out to any part of the drawing field. It is also permissible to perform a turn.
For symmetrical sections in the drawing, the trace of the plane is not shown. Also there is no inscription on such a slice.
Asymmetric sections are performed in a gap or superimposed on a drawing. The trace of the plane for such graphics is depicted, but not signed with letters. Also, there is no inscription.
The extended section is surrounded by a thick, solid outline. If it is applied, the line for its designation is used thin, continuous.
If an object has several identical sections, their outline is denoted by a single letter. Only one slice is drawn.
Simplification
Images (views, sections, sections) for their ease of understanding can be simplified. Standards and norms govern this process.
For symmetrical figures, it is allowed to draw only one half of the cut or most of it with the drawing of a clipping line. When an object has several identical elements, only one of them is drawn. The remaining identical parts are drawn schematically.
Projections of intersection lines may be simplified. But only if their detailed image is not required.
Carrying out the drawing of simple figures, for example, if you need to consider the types of sections of the cone, use a certain approach to graphics. This simplifies the understanding of the drawings. When one surface changes with a specific pattern, it can be interrupted.
If one surface smoothly passes into another, their boundary is not indicated or is indicated conditionally.
Non-hollow symmetrical parts and products in the drawing are shown uncut in the longitudinal section. And if the size of the part of the product in the drawing is less than 2 mm, it is depicted with a deviation from the main scale.
To indicate flat surfaces, diagonals can be drawn in solid lines.
It should also be noted that one- piece connections of electrical or radio devices are simplified by standards appropriate to the type of product. These are the main simplifications that are regulated by the Unified system of design documentation. They are most often used to build drawings in large industries, where it is necessary to depict complex parts, assemblies or mechanisms.
Some special cases of simplifications
If in the drawing sections, sections, views are depicted for regularly changing surfaces, they can be torn. This is done in a certain way. There are three options for limiting.
The first type involves the use of a solid thin broken line. It can go beyond the image border by 2-4 mm. Also, a solid wavy line or shading can connect the contour of parts of the part.
To simplify the drawing, it is allowed to make a dashed line cut between the secant plane and the observer. Complex slices are also used to improve understanding of graphics.
When portraying the holes of some parts (hubs of gears, keyways, pulleys), only their outline is given. If a recess located on a circular flange does not fall into the secant plane, it is depicted in section.
If there is a continuous mesh on the detail of the ornament, it is allowed to depict only a small part of it or simplify the elements of the picture.
Such methods allow to achieve the purity of the drawing, to facilitate its understanding. Indeed, the use of engineering graphics to create all kinds of objects implies the use of a single symbolic language. It should be known to every specialist whose work is associated with this type of image. The quality of the final result depends on this.
Having studied the types of sections, you can understand the basic principles of their implementation and understanding. By applying the recommendations of the standards, you can achieve good clarity. This facilitates the process of its interpretation. Understanding the difference between the view, section and section, knowing their classification and the technology for the correct design of the drawing, a specialist can create the correct image. He will be easily understood by the technician who performs the workpiece or the finished product, and will be able to create units, parts that meet all requirements. The quality of the entire production depends on this process.