Concept of construction drawings. How to learn to read drawings of metal structures correctly? Reading a lathe parts drawing

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Metalwork and tool work

Each working drawing must answer next questions: what part and in what scale is depicted on it, what material is it made of, what are its shape, dimensions as a whole and the dimensions of its individual elements, what deviations from the given dimensions can be allowed, what deviations are allowed in the shape and location of its most important surfaces, with what cleanliness should individual surfaces of the part be processed, etc.

To answer all these questions means reading the drawing. Let's try to get similar answers by referring to Fig. 1. To do this, let's start studying the drawing by reading the stamp of the main inscription, which is always located in the lower right corner of the sheet. First of all, we establish that the drawing shows the body of the combined tool holder, presented in life size, since the stamp indicates a scale of 1:1. The body must be made of 40X steel.

Now let's imagine the shape of the part. To do this, consider the left top part drawing, where the main view of the holder body is drawn. This view should give the most complete picture of it. We establish that the holder consists of a thick part (head), a thin part (tail) and a connecting part. Paying attention to the extended section shown under the main view, we conclude that the tail part of the holder is cylindrical body a flat cut off from the side reading the drawing, as well as a circular chamfer on the right end of the cylinder.

Next you need to establish what the housing head is. From the main view, one can only get the idea that the head has a conical Morse hole No. 4, which then turns into a cylindrical hole with a diameter of 20 mm. It is difficult to judge the external shape of the head by the main appearance alone. To do this, you will obviously have to use the left view and the top view. Referring to the view on the left (in the upper right corner of the drawing), we establish that the head consists of a large cylinder, from which two rectangular protrusions extend to the right and two similar protrusions down. Down side one of the protrusions runs strictly along the central axis of the cylinder. Returning to the main view, we make sure that the protrusions are somewhat shorter than the head cylinder. From the main view and the top view we find two pairs of holes with Ml2 threads on the head. The view on the left clarifies that they are not made in all four, but only in two protrusions.

Rice. 1. Manufacturing drawing of the part.

The shape of the connecting part allows you to set the main view and top view. This part is a cylindrical body (see icon o for size 60C3), through which a through line passes perpendicular to its axis. foramen ovale for knocking out the tool.

So, as the shape of the tail, head and connecting part is studied, the reader of the drawing develops an idea of ​​​​the shape of the holder as a whole.

Now you need to determine the dimensions of the part shown in the drawing. By considering how the dimension lines (lines with arrows) are located and what numbers are in them, you can establish the Dimensions of the part and its individual elements, expressed in millimeter-pax. However, it is important to know not only the size, but also the location of the dimensions on the part. Please note that most of the dimensions are set from one, left end of the part (sizes 250, 135, 98, 88). The surface from which dimensions are set is called the reference base. By putting down the dimensions in this way, the designer thereby instructs the production workers to fulfill precisely these dimensions and maintain them precisely from this surface. These instructions from the designer should be strictly followed, since violation of the reference base during the manufacture of parts leads to deviations from the drawing dimensions and to defects. Therefore, you cannot calculate the dimensions not specified in the drawing yourself and use them in the manufacture of parts.

In addition to the numbers characterizing the dimensions of the part, some dimension lines contain digital and alphabetic symbols. These icons characterize the tolerances for inaccuracy in their implementation. We will get acquainted with the tolerances below. From the data in this drawing, one can also draw a conclusion about the permissible inaccuracy of the position of the surfaces, using already known notations.

From the instructions above the main inscription stamp it is clear that the tail part of the part must be hardened to the hardness indicated in the drawing, and before grinding it must be blued and marked according to the drawing.

The basic requirements for the drawing are as follows:

• 1. The drawing of the part must contain a minimum number of views, cuts and sections, made using only such conventional images as are established by the standards, but sufficient to understand its shape.
• 2. The surface roughness must be indicated on the drawing and all necessary dimensions must be applied geometrically completely and technologically correctly.
• 3. The drawing must contain the necessary technical requirements reflecting the features of the part: material and indicators of its properties, coating, maximum deviations sizes, geometric shape and arrangement of surfaces.

Among the requirements for a part drawing, special mention should be made of the requirement for manufacturability, i.e., the connection of the drawing with the manufacturing technology of the part. The requirement for manufacturability applies both to the design of the part itself and to its depiction in the drawing.

Technologically correct dimensionalization in the drawing is of great importance for the manufacture of parts. In this case, it is necessary to take into account: what elements of parts should be taken as dimensional bases so that they are consistent with the technological and measurement bases; what dimensions to indicate in order to take into account all types of intermediate control during the manufacturing process of the part; what dimensions in the drawing of a part must be coordinated with the corresponding dimensions of adjacent mating parts that interact with this one.

In the production practice of a mechanic (when replacing individual parts that have become unusable during equipment repairs), there is often a need to use sketches.

Sketches are temporary drawings made without the use of a drawing tool and without exact adherence to scale.

When drawing up sketches, the rules established by the standards for drawings should be applied; It is necessary that the sketches are easy and quick to read, do not contain anything superfluous, and meet production requirements.

Reading the drawing begins with familiarization with the main inscription and then proceeds in the following order:

establish the relationship between all images, and also find out which of the simplified and conventional images of part elements are used;

determine the shape of the part, mentally dividing it into its constituent geometric elements;

understand which elements of the part the dimensions refer to, what size they represent (diameter, length, width, etc.), find the dimensions of the base, decipher the size symbols, as well as the designations of surface roughness;

get to know everyone in detail technical requirements and other instructions that determine the features and sequence of work according to the drawing.

Among the graphic documentation that a mechanic uses in the process of work, assembly drawings occupy a large place. They are used for assembly, i.e. connecting parts into assembly units, and then assembly units and parts into finished finished products.

To read and draw up assembly drawings, you need to know and be able to apply the rules, conventions and simplifications established for them by the standards. The main ones are the following:

• 1. Images, views, sections and sections are placed on assembly drawings, as well as on drawings of parts, in projection connection.
• 2. Hatching of adjacent sections of parts on assembly drawings is performed at an angle of 45° in opposite directions or with a shift of the strokes, or with a change in the distance between them.
• 3. Bolts, screws, rivets, keys, rods, solid shafts, balls, spindles, handles, nuts, washers are shown uncut in longitudinal sections.
• 4. Invisible contour lines on assembly drawings are used only to depict simple (invisible) elements, when making cuts does not make the drawing easier to read, but increases its complexity.
• 5. When depicting a threaded rod (bolt, stud, threaded end of a part) screwed into a hole, the external thread (on the rod) is depicted in full, and internal thread(in the hole) is shown only if it is not covered by the thread of the rod.
• 6. The engagement of gears, racks and worms, as well as some other parts, such as springs, are depicted in assembly drawings conditionally (simplified).
• 7. In some cases, complex assembly drawings are supplemented with kinematic diagrams to explain the principle of the mechanism and the interaction of its parts.

When studying the operation of various machines, mechanisms, when setting up or repairing them, during installation electrical equipment It is often necessary to understand the fundamental connection between the elements of a mounted device without specifying it design features. For this purpose are intended various schemes: kinematic, hydraulic, electrical and others.

Kinematic diagrams display the connection and interaction between the moving elements of the device.

Hydraulic diagrams show a fluid control system.

Electrical diagrams explain the principle of operation and the relationship between the elements of an electrical device.

In the diagrams, the details are depicted in a simplified manner, using symbols, established by the standards. The front flyleaf shows a kinematic diagram of a vertical drilling machine with a visual explanation of the symbols of assembly units and parts.

Reading a drawing involves imagining the three-dimensional shape of an object from flat images and determining its dimensions. It is recommended to carry out this work in the following sequence:

1. Read the title block of the drawing. From it you can find out the name of the part, the name of the material from which it is made, the scale of the images and other information.

1. Determine what types of parts are given in the drawing, which of them is the main one.
2. Consider the types in relation to each other and try to determine the shape of the part with all the details. This task is helped by analyzing the images and data in the drawing. Presenting according to the drawing geometric shape each part of the detail, mentally unite them into a single whole.
3. Determine the dimensions of the part and its elements from the drawing. Let's give an example of reading a drawing of a part (first, questions about the drawing are given, and then answers to them).

Questions for the drawing (Fig. 143. The questions are compiled in the sequence corresponding in the correct order reading drawings)

1. What is the name of the part?
2. What material is it made from?
3. What scale is the drawing made at?
4. What types does the drawing contain?
5. Describe the general shape of the part.
6. What are they equal to? dimensions parts and dimensions of individual parts?

Rice. 143. Part drawing

Answers to questions about the drawing (see Fig. 143).

Read the drawing in Figure 145.

Rice. 145. Exercise task

Questions about the drawing

1. What is the name of the part?
2. What material is it made from?
3. What types are shown in the drawing?
4. A combination of which geometric bodies is the shape of the part determined?
5. What parts of the part are shown in the main view by two circles with a diameter of 10?
6. What elements are represented by circles with a diameter of 18 and why are they drawn in the main view with dashed lines?
7. What are the overall dimensions of the part?

Practical work No. 7. 1. Oral reading of drawings

As instructed by the teacher, read one of the drawings in Figure 146. Write down the answers to the questions in your notebook.

Rice. 146. Tasks for practical work № 7

Questions for reading blueprints

1. What is the name of the part? What material is it made from?
2. What scale is indicated in the drawing?
3. Which images convey the shape of the part?
4. What geometric bodies combine to form its shape?
5. Describe the shape of the part.
6. What are the overall dimensions? What is the size of the geometric bodies that form the shape of the part?

2. Solving fun problems

Rice. 148. Exercise tasks

Graphic work No. 8. Drawing an object in three views with transforming its shape (by removing part of the object)

Rice. 151. Tasks for graphic work № 8

Directions for work. Complete tasks 1-4 as preparatory workbook, task 5, as the main one, is on an A4 sheet. Complete the images while maintaining the proportions of the subject; do not apply dimensions.

Reading blueprints is a required skill and a requirement for employment as an engineer of any qualification. This document is the main component of every project, without which neither the development of an oil and gas field nor the construction of a residential building will begin. For successful work with this documentation, the employee must have knowledge in the field exact sciences and have some drawing skills. In this case, reading the drawings will not cause difficulties.

Design organizations provide the operating company with several copies of documentation sets. One of them is a working option for a development company, intended for proper organization work of engineering staff directly on site.

Reading construction drawings allows you to determine the purpose of a building, its exact dimensions, the location of equipment, and the types of structures and materials. Here the designed object is depicted in three versions: facade, plan and sections (longitudinal and transverse). When examining the image of the facade you can see general form building and the height of all elements relative to floor level. This information can be read on the marks placed to the left of the main picture. The location of the entrance and exit, the number of rooms and their purpose, as well as the size and thickness of the partitions are clearly visible.

When designing a residential or industrial buildings, during the development of gas and oil fields, at the first stage, a master plan for the construction site is developed. Reading the general plan drawing gives general idea about this site. Here the layout of buildings, structures, as well as possible natural objects falling within the development area is schematically depicted. If there is an artificial embankment of the territory, the drawings show its section indicating the dimensions and material of the embankment.

In addition, for dangerous and potentially dangerous objects, sections of ITM Civil Defense Emergency Situations (engineering and technical measures of civil defense, measures to prevent emergency situations) and fire safety ( fire safety). For this purpose, general plan drawings are used, which indicate areas of possible damage, their sizes and the location of the accident (pressure pipeline rupture). A detailed reading of the drawings of these sections allows you to plan and timely carry out the necessary rescue measures, since the access points for special fire equipment and personnel evacuation routes are indicated here.

The images contain information about the types of pipes, their diameters, wall thickness, as well as the number and types of valves and adapters.

To ensure that reading the drawings gives a complete picture of the object being designed, a system of abbreviations and symbols is used, which, together with the requirements and standards for development, is regulated state standards RF according to the ESKD system.

Getting to know the product. Using the main inscription, find out the name of the product, the scale of the image, etc.

Reading images. Determine what types, sections, sections are given in the drawing and what is the purpose of each image. Find out the position of the cutting planes with the help of which the cuts and sections are made, and if there are additional and local views, the directions of their projection.

Study of the components of the product. Find out their names using the specification, and find out their shape and relative position using the drawing. Study the component parts of the product in order of specification item numbers, and images of parts should first be found in the view on which the item number is indicated, and then on the others. Take into account that in the presence of cuts, the same inclination and frequency of the hatching lines of its sections contribute to identifying the shape of the part.

Study of product design. Find out the nature of the connection of individual parts to each other. For permanent connections (welded, riveted, soldered, etc.), determine each element and their connection points, and for detachable connections, identify all fasteners.

Determining the sequence of assembly and disassembly of the product. This is the final stage of reading the drawing.

Let's consider an example of reading an assembly drawing of a product shown in Fig. 14.4.

The assembly drawing shows an angular cable plug, as can be seen from the main inscription. It is one of two parts of a connector used to connect an electrical cable. The connection of one part of the connector - the plug - to the other part - the socket - occurs using pin 1 and nut 2.

The assembly drawing shows four images: a full section, part of the view on the left, section A-A and local view B.

The incision reveals internal structure product, the left view makes it possible to understand the shape of the nut 2 and the cup 3. Section A - A reveals the connection of the cup 3 and the body 5. Local view B shows part of the nut 7. View B is made in the direction indicated by the corresponding arrow.

According to the specification shown in Fig. 14.5, we determine that the product consists of one assembly unit (contact), nine parts and three standard screws.

Based on the images in the drawing, we determine the shape of the parts. The body is shown in three images: in the main section, in the left view and in section А-А. The external contours of the body are cylindrical in shape with a right angle bend. The internal shape is represented by two threaded and one smooth holes.

The outer contour of the glass 3 consists of three cylindrical surfaces and one conical surface with a through cylindrical hole. In this case, one cylindrical surface has two slots, shown in the view on the left.

Nut 7 has a slot (slot), shown in local view B, which is designed for screwing it into the threaded hole of the housing.

The nut 10 on the outer diameter of the cylindrical surface has a knurl, shown in part in a sectional view of this part.

Nut 2 has a cylindrical shape with an internal thread M16x 1. There are four through holes on its cylindrical surface.

The design of the product is as follows. The cable is inserted into the housing hole 5, soldered to contact 1 through another hole and closed with a plug 6. The cable is secured in the plug using a nut 7, a seal 8 and another nut 10. A contact / is inserted into the inner hole of the glass 3 and sealed with a sleeve 4. The glass 3 passes through the smooth hole of nut 2 and is secured in the housing using three M2 screws, shown in section A-A.

The product is disassembled in the following order: unscrew the screws 11, remove the cup 3, remove the nut 2. Unscrew the plug and nuts from the threaded holes of the housing and remove the cable.