Graphic representation of details. Engineering graphics

Often the part is so large that its life-size image does not fit on a sheet of paper. It is also difficult to depict a very small detail in life size. To do this, use a reduced or enlarged image of the part.

The number that shows how many times the actual dimensions of the part are reduced or increased is called the scale. The scale cannot be arbitrary. Strictly defined scales are established: for example, for reduction - 1:2, 1:4, 1:50000, etc., and for increase 2:1, 4:1, 10:1, etc. In a drawing made on any scale, provide actual dimensions.

A technical drawing is a three-dimensional image of an object, made by hand using the same lines as the drawing, indicating the dimensions and material from which the product is made. It is built approximately, by eye, maintaining the relationships between the individual parts of the object. The “Ø12” sign in the figure indicates that the hole diameter is 12 mm.

Is it possible to make a product based on a drawing?
What data do you need to know to make a product?
What document is called a design document?
From which document can you find out about the shape and dimensions of the product?
Remember which parts are called symmetrical.
Which line is called the axis of symmetry?

To manufacture any product, you need to determine its shape, dimensions, materials from which it will be made, methods of connecting individual parts, provide what tools are needed for this, etc. Such work at an enterprise is performed by a constructor or designer. They formalize their plans in special documents, the constituent elements of which are graphic images.

Graphic is an image consisting of lines, strokes, dots and drawn with a pencil or ballpoint pen. The main graphic images are a drawing and a sketch (Fig. 36).

Rice. 36. Graphic images: a – detail drawing; b – sketch

Part drawing- this is a document containing a graphic image of a part, made using drawing tools on paper, and the information necessary for its manufacture and control (Fig. 36, a). In practice, graphic images are also used, made in a simplified manner - by hand, without the use of drawing tools, but in compliance with the proportions between the parts of the depicted part (Fig. 36, b). They are called sketches.

Sketches used in the design of new and improvement of existing products. It is with the help of a sketch that an architect, designer, constructor, innovator embodies his idea, his creative concept on paper. Sketches are also carried out when there is an urgent need to manufacture a part instead of one that has failed, and its drawing is missing.

When making graphic images, different types of lines are used, each of which has a specific name and purpose. Information about the drawing lines is presented in Table 2.

Table 2. Drawing lines

In order to be able to use graphic images in any sector of the economy, each country follows the same rules for their implementation. They are defined by a document called the Unified System of Design Documentation (abbreviated as ESKD).

To make it easier to complete the sketch and maintain proportionality between the individual elements of the part when creating a graphic image, it is better to use checkered paper.

In order to make a conclusion about the size of the depicted product or any part of it from the drawing, dimensions are applied to the drawing. There are linear and angular dimensions.

Linear dimensions characterize the length, width, thickness, height, diameter or radius of the product. Angular size characterizes the size of the angle. Linear dimensions in drawings are indicated in millimeters, but units of measurement are not indicated. Angular dimensions are marked in degrees, indicating units of measurement. The numerical value on horizontal dimension lines is placed above the line, and on vertical dimension lines - on the left (Fig. 37).

Rice. 37. Application of numerical dimensions: a – linear; b – corner

When making a graphic image, it is necessary that the total number of dimensions in the drawing be the smallest, but sufficient for the manufacture and control of the product.

When making drawings and sketches, certain conventions are used. Thus, the diameter of parts or holes is marked with the symbol Ø; to indicate the radius, a capital Latin letter R is written in front of the dimensional number. The thickness of flat parts made of plywood, fiberboard, thin sheet metal is marked with the Latin letter S. You will become familiar with other features of the drawings in high school. .

Before you start sketching the product, you need to follow two steps.

Stage one:

prepare a sheet of paper, pencil, eraser, ruler;
carefully examine the existing product, determine the location of holes, recesses, protrusions; determine the approximate (eye) overall dimensions;
find out what graphic image needs to be made to fully understand the shape of the product and the possibility of its manufacture;
measure the overall dimensions of the existing product.

Stage two(Fig. 38):

On a sheet of paper in a box, draw with thin lines a frame in which the sketch of the product will be made. Its dimensions must correspond to the overall dimensions of the product, maintaining proportionality between its elements. Draw axial and center lines (Fig. 38, a); outline the shape of the overall outline of the product with thin lines (Fig. 38, b);
outline the detailed outlines of the product with thin lines: holes, protrusions, other elements, wipe off the excess (Fig. 38, c);
outline the outline of the product with thick lines, put down the dimensions required for the manufacture of the product, according to the ESKD (Fig. 38, d).

You will become familiar with other features of drawings in high school.

Rice. 38. Sequence of sketching a part

To make drawings, you need to have the appropriate drawing tools: a drawing ruler, drawing compasses, squares, a pattern, a protractor, an eraser, pencils of various hardnesses. Check out their purpose in Table 3.

Table 3. Drawing tools

To ensure high-quality execution of graphic images, it is necessary to skillfully organize the workplace and observe the following safe work rules.

Laboratory practical work No. 7. Reading drawings

Equipment and materials: workbook, ruler, compass, pencil.

Work sequence

Check out the detail drawings shown in Figure 40.
Complete their sketches in your workbook.
Determine the following dimensions specific to each drawing:
- length and width of the square;
- the thickness of each part;
- round hole diameter;
- ring radius;
- ring width;
- square hole size.
Write down certain data in the table using the form below.

Rice. 40. Parts drawing

New terms

useful thing, graphic image, design documents, designer, drawing, part, product, sketch, symbols, drawing tools.

Basic Concepts

Image– recreation (display) of something using a drawing, drawing, sketch.
Design document– a graphic document containing all the information for the manufacture of a product and its control.
Marking– drawing the contours of the future part on the surface of the workpiece in accordance with the drawing.
Symbol- an accepted graphic sign, symbol or letter that marks any real object of images.

Fixing the material

What graphic images do you know?
What is a part sketch?
What lines are used in the product drawing?
What lines are called the main ones?
How to correctly indicate the size on the drawing?

Test tasks

1. Establish a correspondence between the designations of the drawing lines and their names and purposes.

solid thin (dimensional) line
solid thin (leader) line
dash-dotted (center) line
dashed (invisible contour line)
solid thick (visible contour line)
dash-dotted center line

2. Which image shows a product whose elements are rectangular in shape?

3. Which drawings show the correct dimensional numbers?

4. Which drawing shows the correct size of the hole diameter?

5. An image of an object made by hand, “by eye”, without a drawing tool, is called...

6. Which line is used to indicate an invisible outline?

7. Which line is used to indicate the axis of symmetry of a part in the drawing?

“Image construction” - Visual impairments. Image of a body lying on an axis. Construction of images. Diffusing lens. Lenses. Inverted real magnified. Converging lens. Image. Characteristics of the image. Direct imaginary diminished.

"Raster images" - Gray. Pink. Red. Vector image. What primary colors does a computer use? How to get any shade in Paint? Blue (turquoise). Green. Let's discuss. Encoding of raster graphic information in the decimal number system. How many bits do we use to encode a color image?

“Images in Word” - 2. In the menu bar, left-click INSERT. Inserting an image from a collection into Word. 7. Left-click INSERT. 3. Left-click FIGURE. 5. In the clip collection window, enter the theme of the image. 5. Select the folder from which you want to insert the image. Left-click START.

“Computer image” - Astana. Reconstruction of the head shape from photographs (2). Computer graphics. The main task of computer graphics algorithms is to create images from a model. At the lecture. Curvilinear surfaces (mirror reflection). Gouraud shading (diffuse reflection). Synthesis of images (screen adaptation).

“Image in Word” - Actions with graphic objects. WordArt objects are a collection of different font styles. For colorful design of your document. To create a shadow of an object. Toolbar – Image settings. Rotate the image. Working with pictures in the text editor Microsoft Word. Tell us what graphic objects can be created using the menu.

“Drawing of a flat part” - Stroke: circles, horizontal lines, vertical, oblique. Clarification of the internal contour of the part. Calculation of the placement of the dimensional rectangle according to the height of the working field using the formula. Analysis of the geometric shape and symmetry of the part. Filling out the title block. Working field. Construction algorithm.

FEDERAL AGENCY FOR EDUCATION

STATE EDUCATIONAL INSTITUTION

HIGHER PROFESSIONAL EDUCATION

VOLGOGRAD STATE TECHNICAL UNIVERSITY

KAMYSHIN TECHNOLOGICAL INSTITUTE (BRANCH)

DEPARTMENT OF “GENERAL TECHNICAL DISCIPLINES”

ENGINEERING GRAPHICS. COMPLEX CUT

Guidelines

to practical classes

RPK "Polytechnic"

Volgograd

Engineering graphics. Complex cuts: Guidelines for practical exercises / Comp. ; Volgograd. state tech. univ. – Volgograd, 2005. – 23 p.

Complex sections used in the process of drawing parts are presented.

Designed for students studying in areas 551700 and specialties 1201, 2803, 2804, 1004, 2202.

Il. 14. Bibliography: 4 titles.

Reviewer

Published by decision of the editorial and publishing council

Volgograd State Technical University

Compiled by: DEMANOVA VALENTINA ANTONOVNA

ENGINEERING GRAPHICS. Complex cuts

Guidelines for practical exercises

Templan 2005, pos. No. 53.

Signed for printing. Format 1/8.

Consumer paper. “Times” typeface.

Conditional oven l. 2.88. Conditional auto l. 2.5.

Circulation 100 copies. Order

Volgograd State Technical University

400131 Volgograd, prosp. them. , 28.

RPK "Polytechnic"

Volgograd State Technical University

400131 Volgograd, st. Sovetskaya, 35

DIV_ADBLOCK14">

technical

university, 2005

SECTIONS AND SECTIONS

1. PURPOSE OF THE TASK

Studying sections and paragraphs of GOST 2.305-68 concerning:

Complex cuts, in particular stepped ones;

Sections, in particular taken out.

Acquiring skills in making a stepped cut, offset section and setting dimensions.

The work is performed on two sheets of format A 3.

Sheet 1: in accordance with the assignment (Appendix B) construct a third image based on two data, make the indicated cuts, construct a natural view of the inclined section (Appendix A).

L East 2: make a visual representation of the model in an axonometric projection (Appendix A).

3. EXECUTION SEQUENCE

View the example doing the work(see Attachment A), read the guidelines, study GOST section 3 “Cuts” and recommended literature;

Carefully familiarize yourself with the design of the model according to your option (see Appendix B);

Plan the working area of the drawing for each image of the model;

Draw axial, symmetry and center lines;

Make the specified cuts and inclined section in the direction specified in the task;

Apply all required dimensions taking into account the rules established

GOST 2.307-68* “Applying dimensions and maximum deviations”;

Draw a rectangular isometric projection of the model, positioning it so that the front right and front left edges of the model are visible. In the axonometric image, cut out the front quarter of the model to show its internal structure more clearly.

4. BRIEF THEORETICAL INFORMATION

Complete the drawing according to the rules of rectangular projection studied in the descriptive geometry course. A distinctive feature of this work is the ability to reveal the internal structure of the model, using complex stepped sections, and to construct the actual size of the inclined section.

4.1 Complex cut

Difficult cut- a cut made by several cutting planes. Complex sections are used in the case when the number of elements of parts, their shape and location cannot be depicted on a simple section using one secant plane and this necessitates the use of several secant planes.

Complex step cut- if the cutting planes are parallel to each other (see Fig. 1).

Complex broken cut- if the cutting planes intersect. With broken cuts, secant planes that are not parallel to the projection plane are conditionally rotated until they are aligned into one plane parallel to any projection plane, and the direction of rotation may not coincide with the direction of view. (see Fig. 2).

Alphabet" href="/text/category/alfavit/" rel="bookmark">alphabet. The section itself is accompanied by an inscription like A-A(see Fig. 1, 2) . Do not underline the inscription!

When developing drawings, in addition to simple and complex sections, they widely use local cuts. Local cuts reveal the design of the product in a separate, limited place: (see Fig. 5 b). They are limited only by a wavy line and are located in the main image of Fig. 1, fig. 5 B.

4.3 Sections

In cases where it is necessary to show the product profile in a given location. hole shape etc. apply section. Sections that are not part of the section are divided into extended and superimposed (see Fig. 4).

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For asymmetrical superimposed sections, the position of the cutting plane is indicated by an open line (two dashes) with arrows, but is not indicated by letters (see Fig. 6).

In all other cases of making sections, the position of the cutting plane is shown by an open line with arrows indicating the direction of view, the same capital letter of the Russian alphabet is written on the outside of the arrows, and above the section itself there is an inscription like A-A. Do not underline the inscription! (see Fig. 7).

The section is designed as a cut if the cutting plane coincides with the axis of the surface of rotation limiting the hole or recess

(see Fig. 8 a).

https://pandia.ru/text/78/495/images/image012_42.jpg" width="21" height="16 src="> (rotate) (see Fig. 9 section

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Instead of secant planes, it is allowed to use secant cylindrical surfaces, which are then developed into a plane, adding an icon to the section designation..gif" alt=" Caption: Fig. 11" width="628" height="717">!}
To construct the natural dimensions of the section, we replace the horizontal plane of projections with a new one, located perpendicular to the frontal plane projection and parallel to the cutting plane A.

The inclined section of the model is a symmetrical cross-sectional figure, this can be seen on the horizontal projection plane, so we begin to build the section from the axis of symmetry 5-5 , which is parallel to the plane A.

We draw the axis of symmetry on the free field of the drawing and measure the marked section points from it. From points 1, 2, 3, 4 and 5 perpendicular to the frontal trace of the plane A we draw new communication lines, on which, on both sides of the axis of symmetry, we plot the natural distances from the axis to the points 1, 2, 3, 4 , measured on a horizontal projection. Distance A from axis to point 1 from the horizontal projection we plot the sections in natural form also from the axis of symmetry. Thus, on a section, all dimensions along the axis of symmetry are measured in full size from the frontal projection, and all dimensions across the axis are transferred from the horizontal projection of the section.

If the inclined section is an asymmetrical figure, then the basis for constructing the section can be any straight line lying in the section plane and drawn parallel to the trace of the cutting plane A. The natural type of section is indicated A-A.

The natural view of the inclined section can also be rotated in order to more conveniently place it on the drawing field, but in this case, next to the section designation, you should put the sign https://pandia.ru/text/78/495/images/image017_29.gif" alt =" Signature: Fig. 12" width="662" height="915">!}

CONTROL QUESTIONS

1. Which cut is called complex?

2. Classification of complex cuts.

3. Features of performing a complex broken cut.

4. Designation of complex cuts.

5. What is the section used for?

6. Classification of sections.

7. When is a section not indicated?

8. When is the section designated?

9. When is a section replaced by a cut?

10. What does the sign mean?

11. What does the sign mean?