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Reading mechanical engineering drawings. Assembly drawing. Reading Assembly Drawings How to Read Technical Drawings

Instructions

When reading a drawing, look at the frame in which it is framed. In the main frame, find information about the name of the part or assembly unit, its number and the material from which it is made (if it is a part). In the case of an image of an assembly unit, you will see in the “Name” column of the main inscription a line in which there will be “ Assembly drawing».

Pay attention to the scale of the image, which should be indicated in the title block of the drawing. It shows how many times the image in the drawing is reduced or enlarged relative to the real object. When designing, magnification scales are used (for example, 2:1, 4:1), which means that the image in the drawing is enlarged compared to the real object. The reduction scale (for example, 1:2, 1:10), in turn, shows how much the image in the drawing is reduced compared to the object.

Find the main view of the depicted object. Most likely, a number of sizes will be printed on it (including dimensions). Take a close look at this view. Pay attention to the cuts and sections, if any, as they give an idea of internal form details. The area of ​​the part or assembly that falls within the plane of the cut or section is shown as shaded in the drawings. Some cuts and sections are presented separately, and they are designated in capital letters with a hyphen (for example, A-A, B-B).

For a more accurate representation of the object, use other views shown in the drawing. Most likely it will be a left view and a top view. Additional species are designated by capital letters (for example, D or G).

Please pay attention to the dimensions provided. They are usually indicated with tolerances that characterize the accuracy of manufacturing a part or assembly unit. The drawing of the part must also include surface roughness symbols.

Read technical requirements. This is the text located above the main title of the drawing. It carries information about the manufacture, storage and operation of the object.

Technological documentation includes route and operational maps. When reading the route map, pay attention to General requirements, presented to a part or assembly. Next you will see the sequence of operations that are necessary to manufacture a particular object. The numbers before the name of the operation characterize the number of the workshop, workplace and the number of the operation itself. Then the sequence of actions is listed, and at the end of the operation the tools and devices used are indicated.

Any electronic device, household appliance, even the furniture in our homes is made on the basis of specially compiled drawings. In which they are drawn first individual elements, and then assembling these parts, showing methods of fastening and positioning them relative to each other. People working in the assembly of products must be able to read drawings, because they serve as a kind of guide to how to assemble what the designer intended, as well as from what material and by what method the necessary parts are made.

Basic Concepts

The term "assembly drawing" means engineering document, which depicts a composite unit with reduction required sizes and technical requirements necessary for its manufacture, as well as quality control. Such a drawing is made when developing product documentation. It should give a complete picture of the location in the finished product relative to other parts. The assembly drawing is carried out in accordance with the requirements of GOST 2.102-68 "Types and completeness of design documents".

A part is a product manufactured according to the requirements of the ESKD from one material and without the use of assembly operations.

Part drawing - a designer’s document containing an image of the part, everything required sizes in order to manufacture it, and the technical requirements prescribe its coating, if necessary.

What should the drawing contain?

Any assembly drawing of a part must contain the following:

How the assembly part is located in the finished product relative to other elements;

How are the parts attached to each other?

Overall dimensions - they will show what length, height and width the product should have;

Installation dimensions - demonstrate the main dimensions of all elements that are needed for installation of the product;

Connecting dimensions - show the dimensions of the joints with other parts or assembly units;

Reference dimensions - indicated on the drawing from reference books (on standard sizes threads, nuts, etc.);

Maximum permissible deviations during manufacturing, according to which product quality control will be carried out;

Methods of fastening parts together, indicating all connections and methods for their implementation;

The positions of each part in the assembly included in the specification;

The scale in which the drawing is made;

Product weight.

Basic rules for making assembly drawings

The assembly drawing is completed in accordance with the requirements of GOST 2.109-73. If you need to indicate rotating or moving parts of the product, then it is allowed to show them either in an extreme or in an intermediate position. In this case, it is necessary to indicate the required dimensions. If reading the assembly drawing becomes difficult, then it is permissible to show some parts separately, making the necessary signatures indicating the positions.

When making sections or cuts on the same part, you must maintain the same slope of the lines and the distance between them when performing hatching.

If a cut is made at the junction of two different parts, then hatching at the cut site of each of them is applied in different directions or with different distances between inclined lines.

If necessary, the drawing indicates roughness and permissible deviations from the norm for some specific parts or holes. There are also a number of standard parts for which separate drawings can be omitted, but if there is a lack of necessary information they are placed on the field of the assembly drawing.

If the joining of individual parts must be ensured by fitting or selection, then appropriate signatures are made.

Specifying Part Positions

All components of the assembly unit are numbered according to GOST 2.109-73.

Each component, as well as the materials used, standard products must have its own serial number, which is assigned to them when drawing up the specification for this assembly drawing.

All positions in the drawing are indicated by leader lines that are drawn from each individual part or material. The end of the line, which is located in the image of the part itself, is thickened with a dot. The line itself and the leader shelf are depicted as a continuous thin line. All positions are indicated visible details. The positions of invisible parts are indicated in additional views or sections.

Position inscriptions are made parallel to the main inscription in the drawing frame. Also, positions should be placed outside the outline of the parts; they can be grouped.

If the same part is present on the assembly drawing several times, then its position is indicated only once, and in parentheses next to the number it is indicated how many times it is repeated in the drawing.

Item numbers are indicated in a font that is 2 sizes larger than in the technical requirements and frame.

Intersecting lines when placing positions is not allowed, and they should not have the same direction as the hatch lines.

Simplifications and symbols in drawings

When making an assembly drawing, you can use acceptable symbols and simplifications.

The drawings may not show chamfers, grooves, roundings, small protrusions, recesses, etc., as well as some gaps if they are small.

If the drawing needs to depict those parts of the product that are covered with a lid or shield, then the latter may not be shown. They also add an inscription indicating which item's detail is not shown.

If the same component (wheel, support) is used several times in a product, it is allowed to show its image only once.

Soldering, gluing or welding areas can be shown as uniform surfaces. In this case, boundaries are left between sections of different parts.

Also, according to GOST 2.315-68, fastening parts are shown in a simplified manner.

Specification

This is a design document that specifies the full composition of the assembly product in accordance with GOST 2.108-68. This document performed on A4 format separately for each assembly. It consistently describes all the components of the assembly unit.

Based on the general case, the specification is compiled from the following sections sequentially: documentation, assembly parts, parts, standard products, other products, materials, kits.

It is not necessary for all sections to be present in every specification. If one of them is not filled out, it is simply not registered. The title of the section is written by skipping two lines from the last entry of the previous one; in the middle of the column is the name, underlined by a thin straight line.

Products are recorded in alphabetical order. The numbering of positions goes from the first section through the entire document. Also in the corresponding column the GOST or designation of an individual part and their quantity in a given assembly are indicated.

Sequence of assembly drawings

An assembly drawing is made either from a finished product, or first a sketch of the parts is made in programs such as SolidWorks, Kompas 3D, and only then the drawings themselves are created from them.

Before you start drawing, you need to:

Study the details, operating principle of the product and its purpose;

Determine the order in which the finished product will be assembled;

Make a plan indicating all components;

Select the most informative images for placement on the drawing field, make the minimum number additional types and cuts;

Based on the size of the selected image, the number of views and sections, choose the most suitable size format;

Fill in the drawing frame;

Draw all the images, check the work done;

Enter all dimensions, numbering of positions, sign everything;

Write technical requirements for manufacturing a part according to this drawing;

Fill out the specification.

Below are the most simple examples assembly drawings.

How to read assembly drawings correctly

Reading assembly drawings implies, first of all, a preliminary study of information about how the product is constructed and how it works.

Understand the principle of operation and what this product is intended for, based on the inscriptions in the document frame;

Determine what components the product consists of according to the specification;

Understand why each individual part is needed, its location and operation in relation to other elements;

Determine the sequence in which the product will be disassembled and assembled (reading the main inscription in the frame, the contents of the drawing and its features, correlating the information in the specification and on the drawing field);

Study the description of the finished product or its analogue;

Find out the way in which the individual parts are attached to each other.

Detailing general view drawings

Detailing an assembly drawing is quite a painstaking and difficult job. Having only general assembly parts, based on this drawing and specification, you need to make drawings of all parts, and choose the most convenient angle for their implementation and applying all the necessary dimensions and designations.

What size an individual part will be will be determined based on the scale general drawing and the size of this part on it. Dimensions for standard parts are taken from a standards reference book and not from drawing data.

Detailing an assembly drawing usually consists of three stages:

Reading an assembly drawing that has general form;

Determination of the shapes of individual parts;

Drawing of every detail.

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 the overall dimensions of the parts and the dimensions of the 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.

Read general view drawing- means finding out the purpose of this product, the structure and principle of its operation, getting a complete understanding of the shape, size and technical specifications the finished product and each part separately, i.e. determine from the drawing all the data for their manufacture and control.

When reading the general view drawing they find out mutual arrangement components of the product, methods of connecting parts, as well as geometric shapes and sizes of all elements of the product.

Assembly, installation, repair or improvement of even simple assembly units are associated with the study of the design from a general drawing.

Since working drawings are developed based on the general drawing,

of parts, it must contain a sufficient number of images to allow such drawings to be made.

The task offered to students requires them to read a general drawing and use it to make working drawings of parts (as directed by the teacher).

1. Familiarize yourself with the contents of the main inscription placed in the lower right corner of the drawing. Determine the product name, drawing number, scale, etc. from the inscription. Often the name of the product says a lot about its purpose and operating conditions (for example, “Shut-off valve”, “Pneumatic vice”, etc.).

2. Familiarize yourself with the purpose and operating principle of the depicted product using the set of design documents attached to the drawing, in particular the explanatory note and technical specifications.

3. Study the images on the drawing: find out the location of the front view (main view); establish the number of main, additional and local views in which the drawing is made; determine which sections are used in the drawing (simple or complex); set the direction of the cutting plane for each cut; note the presence of sections, extensions, etc.

4. Familiarize yourself with the contents of this product; set the name of each part and consistently find each part in the drawing (on all views, sections and sections).



Based on the images found, determine the geometric shape and design features details.

Clarification of the shape of each part is facilitated by the fact that in all sections and sections the same part is shaded with the same slope and the same distance between the lines.

5. Establish the nature of the connection of individual parts.

For permanent connections (welded, riveted, soldered, etc.), determine each element of the connection (for example, each individual weld).

For detachable connections, identify all fasteners included in the connection.

For moving parts, it is necessary to determine the process for their re-

displacement during operation of the mechanism (interaction of parts). It is necessary to establish which surfaces of the parts are mating and along what dimensions of the surfaces the connection is made.

Based on the general view drawing, the fit of the parts is determined, guaranteeing their interaction in the product.

6. Determine which moving surfaces of parts are lubricated and how this lubrication is carried out.

7. Establish the procedure for assembling and disassembling the product. In this case, it is necessary to highlight standardized and normalized parts for which working drawings are not drawn up.

Let's consider the procedure for reading a general drawing using the example of an assembly unit shown in Fig. 10.1.

From the main inscription it is clear that the drawing shows a plug valve on a scale of 1:1.

From the description, which is usually attached to general drawings for educational purposes, you can find out that a plug valve is one of the types of pipeline fittings and is intended to change the supply of liquid (gas) passing through a pipeline. Plug valves are installed where a quick change in the supply of liquid (gas) is required, since to fully open the valve it is enough to turn the plug at an angle of 90°.

The plug tap drawing contains three images. In place of the main view there is a frontal section, which shows the interaction of the main parts.

The faucet consists of a body 1 in which a conical plug 2 is installed (when turned, it changes the cross-section or completely closes the hole in the body). The plug 2 is pressed to the conical surface housing 1. Bushing 4 and stuffing box 11 (felt) seal the movable connection of parts 3 and 2.

In the view on the left, a local section is made, explaining the design of the connection between the housing and the cover with screw 5.

According to the specification (Fig. 10.2), we determine the composition of the parts included in the product “Plug tap”.

The product consists of 11 types of components, which include five original parts, five standard products and one material. All original parts are included in the product in a single copy. There is no drawing for part 5 “Gasket”, but the dimensions and shape of the part are explained in the specification.

Let's start getting acquainted with the original parts of the crane with the body. Studying the shape of this part in each view and comparing the views with each other, let us imagine an image of the body.

Since in the views the image of the body is partially covered by the image of the parts located inside or by the upper parts, it is necessary to supplement and combine into a single image all the available images of the body elements in the drawing.

The central part of the body has the shape of a truncated cone, which has pipes on the right and left. At the end of the right pipe there is a G1 cylindrical pipe thread. There is a flange at the end of the left pipe triangular shape with three through cylindrical holes Ø9. On top of the body there is a round flange with four threaded holes for attaching the cover.

The described shape of the body is comparable to the image in Fig. 10.3. The housing drawing is given in the appendix. 14.

Having dealt with the image of the main part (body 1), let's move on to studying the remaining parts (2, 3, 4). First, we will consider each of them in detail on the assembly drawing.

Plug 2 consists of a truncated cone with a radial hole and a cylindrical rod with a shank square section. Oval shape holes are determined by the view on the left, and square shape the shank can be read from the top view (Fig. 10.1). The shape of the plug is shown in Fig. 10.4 (a drawing of the plug is given in Appendix 15).

An image of cover 3 (Fig. 10.1) is shown in Fig. 10.5. Let's determine the shape of the cover elements from the assembly drawing and compare them with the image in Fig. 10.5 (a drawing of the cover is given in Appendix 15).

Rice. 10.4 Fig. 10.5

Determine the shape of the “Bulb” part yourself from the images available in the drawing (Fig. 10.1), then compare with the drawing given in the appendix. 17.

Every time you read a general view drawing, you must compare the drawing of a separate part with its image on the assembly drawing.

After the shape of the individual parts has been studied, it is necessary to establish how the parts are connected to each other and the possibility of movement of one part relative to another.

Thus, analyzing the relative position of the parts in Fig. 10.1, we determine that cover 3 is attached to the body using four screws 5.

On the cover 3 there is an oil seal sleeve 4, which ensures sealing of the felt packing 11. The oil seal is pressed against the cover using studs 9 and nuts 6.

The only moving part in this mechanism is the plug, which can rotate around its axis.

The valve in the drawing is shown in the open position.

Reading blueprints is a required skill and a requirement for employment as an engineer of any qualification. This document is the main component of each 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 the building, its exact dimensions, the location of equipment, as well as 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 the general appearance of the building and the height of all elements relative to the 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, which, together with the requirements and standards for development, is regulated state standards RF according to the ESKD system.