Types of product images in the drawing. Types of main, additional and local Three types in the drawing examples
Building views begins with the mental selection of the position of the part in front of the projection planes. Then select the number of views necessary and sufficient to identify the shape of the part, as well as the method of their construction.
The choice of the position of the part in the system of projection planes depends on its working position, manufacturing method in production, and shape. For example, if a part is made on a lathe, then in the drawing its axis of rotation should be located horizontally.
Drawing views can be made in various ways. Let's look at some of them.
Construction of views based on sequential drawing of geometric bodies that make up the shape of an object. In order to complete a drawing in this way, it is necessary to mentally divide the part into its simple geometric bodies, finding out how they are located relative to each other. Then you need to select the main type of part and the number of images that allow you to understand its shape and sequentially depict one geometric body after another until the object’s shape is completely displayed. It is necessary to observe the dimensions of the form and correctly orient its elements relative to each other (Table 8).
The construction of views based on element-by-element drawing of geometric bodies that make up the shape of an object is carried out using the techniques of deletion and increment.
When drawing a geometric body using the deletion technique, the shape of the workpiece is successively changed in the drawing by removing volumes similar to the methods of processing it by turning, drilling, milling, etc.
When drawing a geometric body using the increment technique, the volumes of the product elements seem to complement each other and are incremented.
8. Element-by-element drawing of geometric bodies that make up the shape of an object
Constructing views using a constant straight line drawing (external coordination method). A constant straight line in a drawing is a line drawn from the center of coordinates (point O) down to the right at an angle of 45° (Fig. 86).
The object is mentally placed in a system of projection planes. The axes of the projection planes are taken as coordinate axes. The projection connection between the top view and the left view is carried out using projection connection lines, which are drawn until they intersect with the constant straight line of the drawing and are built at an angle of 90° to each other.
A constant straight line of a drawing is, as a rule, used in cases where, based on two given views, it is necessary to construct a third view of a part (see Fig. 86). Having redrawn two types of parts, construct a constant straight line of the drawing and draw projection connection lines parallel to the OX axis until they intersect with the constant straight line of the drawing, and then parallel to the OZ axis.
The considered method of construction is called the method of external coordination, since the object is fixed in space relative to the axes of projection planes, which are located outside the depicted object.
(If the drawing does not show the projection axes and it is necessary to perform a third view of the part, then you can construct a constant drawing straight line anywhere on the right side of the top view.)
Constructing views using internal object coordination. Internal coordination consists in the mental introduction of additional coordinate axes tied to the projected object.
Rice. 86. Construction of the third projection from two given ones using a constant line drawing
Rice. 87. Constructing views using a method of internal coordination of an object
To understand the drawings, you need to know well how the views are arranged on them.
View called the image of the visible part of the surface of an object facing the observer.
The names of the species depend on which side the object is viewed from. Viewing directions are shown in Fig. 3, and arrows with inscriptions.
The original is front view, which is also called main view.
If you look at the object on the left, at right angles to the original position of the part, you get left view.
When looking at an object from above, perpendicular to the horizontal plane, we get top view.
What do you call the view if you look at the part from below? Left view? Right view? Bottom view? (Choose the correct answer).
Each type has a strictly defined place in the drawing. The view on the left is located to the right of the main view and on the same level with it, the view from above is under the main view (Fig. 3, b). You cannot break this rule by placing views in random places.
Knowing the rule for the arrangement of views, you can imagine the shape of an object from its flat images. To do this, you need to compare all the views given in the drawing and recreate in your imagination the three-dimensional shape of the object.
Answer the questions?
1. What is called a view in drawing?
2. Which image in the drawing is the original one?
3. Write down the names of species known to you.
4. Depending on what is the name given to the species?
5. How are the views arranged in the drawing?
6. Is arbitrary arrangement of views acceptable?
7. How to represent the three-dimensional shape of an object using flat images?
Tasks for § 1
Exercise 1
(Exercises for which answers are given at the end of the book are marked with a *.)
A. In Fig. 4, and a drawing is given containing three views. Each type is marked with a number. What is the name of each of the species given in Fig. 4, huh? Write their names in your workbook.
B. From four visual representations of various parts placed in fig. 4.6, only one is a picture of the part shown in Fig. 4, a. Write down the number of this visual image in your notebook.
B. What is the direction of view indicated by the arrow with the letter in Fig. 4, b, corresponds to the main view, left view, top view, shown in Fig. 4, a. Write the answer in your notebook in the following form: Direction B corresponds to the main view.
Exercise 2
A. What are the names of the species shown in Fig. 5, god? Write their names in your notebook. B. From the three drawings in Fig. 5, b-d, only one shows a detail corresponding to the visual image in Fig. 5, a. Which one? Write down its number in your notebook.
B. What is the direction of view indicated by the arrows with letters in Fig. 5, a, corresponds to the main view, top view, left view? An example of a response: Direction... corresponds to the main view.
Exercise 3
Using visual images of objects, find their drawings (Fig. 6). Write down in your notebook which visual image, indicated by a letter, corresponds to the drawing, indicated by a number.
| Digital designation | Species name |
|---|---|
| A | |
The rules for depicting products on drawings of all industries and construction are established by GOST 2.305-2008. Images of objects are made using the rectangular projection method. In this case, the object is placed between the observer and the corresponding projection plane (Fig. 15). The main projection planes are the six faces of the cube onto which the object is projected; the edges are aligned with the plane, as shown in the figure.
The images in the drawing, depending on their content, are divided into species,cuts And sections.
The number of images (types, sections, sections) should be the smallest, but providing a complete picture of the subject when using the symbols, signs and inscriptions established in the relevant standards.
8.1. Species
View is an orthogonal projection of the visible part of the surface of an object facing the observer.
Types are divided into basic, additional and local.
Main types– views obtained on the main projection planes (cube faces). The standard establishes the following names of the main types (Fig. 16):
1 – front view (main view);
2 – top view;
3 – left view;
4 – right view;
5 – bottom view;
6 – rear view.
Rice. 16. Main types
If the arrangement of views in the drawing corresponds to Fig. 16, then the names of the types in the drawing are not signed. Main view of the item (main view) - the main view of an object on the frontal projection plane, which gives the most complete idea of the shape and size of the object, relative to which the other main views are located. If the views from above, left, right, below, behind are not in projection connection with the main image, then they are marked on the drawing as ""А"" (Fig. 17).
Rice. 17. Designation of a view located outside the projection connection
The direction of view is indicated by an arrow, indicated by a capital letter of the Russian alphabet, starting with the letter À. Drawings are also drawn up if the view is separated from the main image by other images (Fig. 18) or is not located on the same sheet with the main image.
Rice. 18. Identification of a view separated by another image
The font size of the letter designations is approximately twice the size of the digits of the dimension numbers. The arrows indicating the direction of view should be the same in shape as the dimensional ones, but larger, with a thickened linear part.
Additional views– images on planes not parallel to the main projection planes. They are used in cases where any part of an object cannot be shown in the main views without distorting its shape and size.
An additional view is marked on the drawing with an inscription like ““А””, and the image of the object associated with it should have an arrow indicating the direction of view, with a corresponding letter designation (Fig. 19).
Rice. 19. Location of additional views
The additional view can be rotated relative to the specified viewing direction, while maintaining the position taken for a given object in the main image. In this case, the sign “” is added to the inscription ““А” (Fig. 19), replacing the word ““rotated””.
The dimensions of the arrows indicating the direction of view and the sign are shown in Fig. 20.
Rice. 20. Arrows for additional and rotated views
When an additional view is located in direct projection connection with the corresponding image, the arrow and view designation are not applied.
Local view– an image of a separate limited area of the surface of an object on one of the main projection planes (Fig. 21).
Rice. 21. Image and designation of a local species
The local view may be limited to the cliff line, as small as possible, or not limited. The detail view should be marked on the drawing like the supplementary view.
Basic, additional and local views are used to depict the shape of the external surfaces of an object. Revealing the shape of the internal surfaces of an object with dashed lines makes it much more difficult to read the drawing and complicates drawing dimensions. Therefore, to identify the internal (invisible) configuration of an object, they use cuts and sections.
The main method of depicting objects in a drawing is projection (from the Latin projectio– throwing forward, into the distance).
Let's consider the main elements and essence of the projection method using the example of a point (Figure 31):
· projection plane P’ – the plane onto which the projection is performed;
projection center S – the point from which the projection is made;
points A, B - projection objects;
· projecting beams SA and SB – imaginary lines with the help of which projection is carried out.
Figure 31. Projection method.
Drawing a straight line through the center of the projections S and point A until it intersects with the plane P', we obtain point A'. Point A’ is the projection of point A onto the plane P’. Symbolically this 
.
Drawing a straight line through the center of the projections S and point B until it intersects with the plane P', we obtain point B'. Point B’ is the projection of point B onto the plane P’. Symbolically this 
.
If the center of projections S is at a finite distance (i.e. all rays of projections come out of it), then the projection is called central.
If the center of projections S is a point at infinity, then in observable space the projecting rays will be parallel. In this case, projection is called parallel(Figure 32).
If the projecting lines are perpendicular to the plane of projections, then the projection is called orthogonal or rectangular(Figure 33).
If the projecting rays are not perpendicular to the projection plane, then the projection is called oblique.
During the process of projection, the figure being projected changes, it loses its properties and acquires new ones. Some properties remain unchanged:
1. The projection of a point is a point.
2. If one figure belongs to another figure, then the projection of the first figure belongs to the projection of the second figure.
Figure 32. Parallel Figure 33. Orthogonal
projection projection
3. If a figure belongs to a plane parallel to the projection plane, then the projection of the figure onto this projection plane is equal to the figure itself, i.e. life-size.
A drawing consisting of projections of an object is called complex drawing To obtain a complex drawing, use the following algorithm:
1. The object is projected orthogonally onto three mutually perpendicular planes (Figure 34).
2. These planes are combined into one by rotating around the line of intersection of these planes (Figure 35).
To build a third projection based on two data, you must do the following:
1. Through the frontal projection A 2, draw a perpendicular to the z axis.
2. On the drawn perpendicular from the z axis, lay off a segment equal to the distance from the horizontal projection A 1 to the x axis.
Figure 34. Projecting a point onto three projection planes.
Figure 35. Complex drawing of a point.
When making mechanical engineering drawings, the rules of rectangular projection are used. An object is projected onto 6 faces of a hollow cube, placing it between the observer and the corresponding face of the cube. The faces of the cube are taken as the main projection planes. Consequently, there are 6 main projection planes (Figure 36). These planes are combined by turning them into one plane along with the images obtained on them.
The image on the frontal plane of projections in the drawing is taken as the main one. The object is positioned so that the image on the frontal plane gives the most complete idea of the shape and size of the object.
In engineering graphics, images of objects are called views.
View– an image of the visible part of the surface of an object facing the observer.
In order to reduce the number of images, it is allowed to show invisible contours of an object with dashed lines in views.
All views in the drawing must be located in a projection relationship. This makes the drawings easier to read. In this case, no inscriptions explaining the name of the species are applied. The number of views in the drawing should be the smallest, but providing a complete picture of the subject.
Figure 36. Formation of main species.
According to GOST 2.305 – 68, the following species names are established (Figure 36):
1- Front view (main view);
2- Top view;
3- Left view;
4- Right view;
5- Bottom view;
6- Rear view.
Figure 37. Location of main views in the drawing.
Axonometric projections.
In addition to rectangular (orthogonal) projections, axonometric projections are used to depict an object in a drawing.
The drawing gives a clear idea of the shape and size of the object, but in some cases a visual representation of the object is required.
In these cases, an additional image of this object is provided in an axonometric projection.
The method of axonometric projection is that a given object, together with the coordinate axes to which this object is assigned in space, is parallelly projected onto a certain plane (Figure 38). Therefore, an axonometric projection is a projection onto only one plane.
Depending on the direction of projection, axonometric projections are divided into two types:
Oblique projection– projection is not perpendicular to the plane of axonometric projections;
Rectangular projection– projection perpendicular to the plane of axonometric projections.
Figure 38. Axonometric projection.
Ratios of distances along axes in space to the resulting axonometric projections of these distances: e x /e = k; e y /e = m; e z /e = n.
k, m, n are called axis distortion coefficients.
Depending on the magnitude of the coefficients, axonometry is divided into three types:
Isometric: k = m = n;
Dimetry: k = m ≠ n (e x = e z ≠ e y);
Trimetry: k ≠ m ≠ n.
Trimetry is used very rarely.
GOST 2.317 - 69 establishes the rules for constructing axonometric projections used in drawings of all industries and construction.
Dimetric projection.
The y-axis distortion coefficient is 0.47, and the x- and z-axis distortion coefficient is 0.94.
It is customary to perform a dimetric projection without distortion along the x and z axes, i.e. equal to 1, and along the y-axis - 0.5 (2 times less).
Circles in axonometry are projected into an ellipse. The major axis of the ellipses will be 1.06d, d is the diameter of the circle, and the minor axis of the ellipse in the xz plane will be 0.95d, ellipses in the xy and zy planes will be 0.35d.
Figure 39. Dimetric projection.
Isometric projection.
The distortion coefficients along all axes are equal to 1. The major axis of the ellipses is 1.22d, the minor axis of the ellipses is 0.71d, where d is the diameter of the circle.
Figure 40. Isometric projection.
APPLICATION
GBPOU "Kurgan State College"
TEST
Specialty 08.02.01 Construction and operation of buildings and structures (correspondence department)
Group ZS 102
Full name student Ivanov I.I.
Option 0
Subject: Engineering graphics
Teacher: Beloshevskaya M.A.
Job registration date:
Teacher rating:
Kurgan 2016
Figure 1. Example of task No. 1 “Title page”
Figure 2. Example of task No. 2 “Drawing lines”
Figure 3. Example of completing task No. 3 “Geometric constructions”
Figure 4. Example of task 4 “Part projections”, sheet 1
Figure 5. Example of task 4 “Part projections”, sheet 2.
References:
1. Bogolyubov S.K. Engineering graphics. – M.: Mechanical Engineering, 2000.
2. Kulikov V.P., Kuzin A.V. Engineering graphics: textbook – 3rd edition, rev. – M.:FORUM, 2009.-368 p.- (Professional education).
3. Chekmarev, A.A., Osipov V.K. Handbook of mechanical engineering drawing - M.: Higher School, 2001 - 360 p.
4. Chumachenko G.V. Technical drawing: textbook. allowance for vocational schools and technical lyceums / G.V. Chumachenko, Ph.D. those. Sci. –Ed. 6th, erased. – Rostov n/d: Phoenix, 2013. -349 p. – (NGO).
5.alldrawings. ru.
6. nacherchy. ru.
7. Bogolyubov S.K. Engineering graphics. – M.: Mechanical Engineering, 2000.
8. Belyagin, S.N. Drawing: reference. allowance / S.N. Belyagin. – 4th ed., add. – M.: LLC Publishing House AST: LLC Publishing House Astrel, 2002-424p.
9. State standards. Unified system of design documentation.
10. Vyshnepolsky, I.S. Technical drawing: textbook. for students average prof. Education / I.S. Vyshnepolsky. – M.: Higher School, 2001. – 392 p.
11. Mironov B.G., Collection of tasks on engineering graphics with examples of making drawings on a computer: Textbook. allowance / B.G Mironov, R.S. Mironova, D.A. Pyatnik, A.A. Puzikov – 3rd ed., revised. and additional – M.: Higher. school, 2003.-355p.
12. Stepakova V.V., Gordienko N.A. Drawing. – M.: Astrel Publishing House LLC, 2004 – 272 p.
13. Chekmarev A.A., Osipov V.K., Handbook of mechanical engineering drawing - M.: Higher School, 2001 - 360 p.
It is known that frontal, horizontal and profile projections are images of a projection drawing. Species It is customary to name those images on mechanical engineering drawings that represent projections of the external visible surfaces of objects. It can also be said that under species refers to the visible parts of the surfaces of objects facing the observer and shown in the drawings.
Arrangement of views in the drawing
According to the current standard, three types are distinguished: basic, local and additional.
Guided by GOST 2.305 – 68, species, which are obtained on all main projections of planes, have the following names:
Main view(front view). It is located in the place where it is located frontal projection
Top view. Located under the main view, that is, in the place where the horizontal projection is located
Left view. Placed to the right of the main view, in the place where the profile projection is located
Right view. Located on the left side of the main view
Bottom view. Placed above the main view
Rear view. Located on the right side of the view on the left
Just like all projections, the main views are in a projection relationship. When drawing up mechanical engineering drawings, developers try to select as few views as possible, and at the same time, so that the shape of the depicted object is represented accurately and in all details. In cases where this is necessary, those parts of the surfaces of objects that are invisible can be designated using dashed lines.
The most complete information about the object depicted in the drawing should be provided by the main view. For this reason, the location of the part relative to the frontal plane of projections must be carried out in such a way that it is possible to project its visible surfaces indicating the largest number of elements that determine the shape. In addition, it is the main view that should demonstrate all the features of the part’s shape, ledges, surface bends, silhouette, holes, and notches. This must be done in order to ensure the fastest possible recognition of the shape that the depicted product has.
On drawing graphic documents, names of types are not applied, except in cases where they are in direct and immediate projection connection with the main image of the part.
Views outside the projection link
In order to use the working field of the drawing in the most rational way, in accordance with current norms and standards, it is allowed to depict views in any place, and without any projection connection.
Those views that are located without a projection connection with the main view should be designated by different letters of the Cyrillic alphabet (Russian alphabet), and as for the direction, arrows should be used to indicate it.
Arrow sizes
All arrows that are placed on the drawings in the case of displaying a view outside the projection connection must have strictly defined dimensions, which are established by current standards.
Arrangement of views on the drawing field
The main requirement that the placement of the main and other main views on the drawings must meet is rationality. In this case, it is also necessary to take into account the placement of text material and the need to apply dimensions. According to current standards, it is not permissible to arrange views on drawings in such a way that it interferes with the full representation of the part's shape in the main view.
Rational arrangement of species
The rational arrangement of views in mechanical engineering drawings means their placement in such a way that gives a complete idea of the shape and all the features of the depicted part.
Applying breaks
In cases where the objects depicted in the drawings have areas where the cross-section is either constant or changes in a regular manner, it is permissible to depict them with breaks. In this case, the contours of these breaks should be indicated using a solid thin wavy line.
Local view
Local view refers to an image of a separate section of the surface of an object, which is formed by projecting it onto one of the main projection planes.
It is permissible to limit the local view using a thin wavy cliff line. In cases where a local view is depicted outside the projection connection, the direction of view on the main view is indicated with an arrow, and a letter designation is applied to this local view.
Additional views
