2.1. The concept of ESKD standards. If every engineer or draftsman performed and designed the drawings in his own way, without observing uniform rules, then such drawings would not be understandable to others. To avoid this, the state standards of the Unified System for Design Documentation (ESKD) have been adopted and are in force in the USSR.

ESKD standards are regulatory documents that establish uniform rules for the implementation and execution of design documents in all industries. Design documents include drawings of parts, assembly drawings, diagrams, some text documents, etc.

Standards are set not only for design documents, but also for certain types of products manufactured by our enterprises. State standards (GOST) are mandatory for all enterprises and individuals.

Each standard is assigned its own number with the simultaneous indication of the year of its registration.

The standards are revised from time to time. Changes in standards are associated with the development of industry and the improvement of engineering graphics.

For the first time in our country, standards for drawings were introduced in 1928 under the name "Drawings for all types of mechanical engineering." Later they were replaced by new ones.

2.2. Formats. The main text of the drawing. Drawings and other design documents for industry and construction are performed on sheets of certain sizes.

For the economical use of paper, the convenience of storing drawings and using them, the standard establishes certain sheet formats that are outlined with a thin line. At school, you will use a format whose sides are 297X210 mm. It is designated A4.

Each drawing must have a frame that limits its field (Fig. 18). The frame lines are solid thick main lines. They are carried out from above, to the right and from below at a distance of 5 mm from the outer frame, performed by a solid thin line along which the sheets are cut. On the left side - at a distance of 20 mm from it. This strip is left for filing drawings.

Rice. 18. Making an A4 sheet

In the drawings, the main inscription is placed in the lower right corner (see Fig. 18). Its form, dimensions and content are established by the standard. On educational school drawings, you will perform the main inscription in the form of a rectangle with sides of 22X145 mm (Fig. 19, a). A sample of the completed title block is shown in Figure 19, b.

Rice. 19. The main inscription of the training drawing

Production drawings, performed on A4 sheets, are placed only vertically, and the main inscription on them is only along the short side. In drawings of other formats, the title block can be placed along both the long and short sides.

As an exception, on A4 training drawings, the main inscription is allowed to be placed both along the long and along the short side of the sheet.

Before starting the drawing, the sheet is applied to the drawing board. To do this, attach it with one button, for example, in the upper left corner. Then a T-square is placed on the board and the upper edge of the sheet is placed parallel to its edge, as shown in Figure 20. Pressing a sheet of paper to the board, attach it with buttons, first in the lower right corner, and then in the other corners.

Rice. 20. Preparing the sheet for work

The frame and columns of the main inscription are made with a solid thick line.

What are the dimensions of an A4 sheet? At what distance from the outer frame should the drawing frame lines be drawn? Where is the title block placed on the drawing? Name its dimensions. Consider Figure 19 and list what information is indicated in it.

2.3. Lines. When making drawings, lines of various thicknesses and styles are used. Each of them has its own purpose.

Rice. 21. Drawing lines

Figure 21 shows an image of a part called a roller. As you can see, the detail drawing contains different lines. In order for the image to be clear to everyone, the state standard establishes the style of lines and indicates their main purpose for all drawings of industry and construction. In the lessons of technical and service labor, you have already used various lines. Let's remember them.

In conclusion, it should be noted that the thickness of lines of the same type should be the same for all images in a given drawing.

Information about the lines of the drawing is given on the first flyleaf.

1. What is the purpose of a solid thick main line?
2. What is a dashed line? Where is it used? What is the thickness of this line?
3. Where is a dash-dot thin line used in a drawing? What is its thickness?
4. In what cases is a solid thin line used in a drawing? How thick should it be?
5. Which line shows the fold line on the scan?

In Figure 23 you see a picture of the part. Various lines are marked on it with the numbers 1,2, etc. Make a table in your workbook according to this sample and fill it out.

Rice. 23. Task for exercises

Graphic Work No. 1

Prepare an A4 sheet of drawing paper. Draw the frame and columns of the title block according to the dimensions indicated in Figure 19. Draw different lines, as shown in Figure 24. You can also choose a different arrangement of line groups on the sheet.

Rice. 24. Task for graphic work No. 1

The main inscription can be placed both along the short and along the long side of the sheet.

2.4. Drawing fonts. Sizes of letters and numbers of the drawing font. All inscriptions on the drawings must be made in drawing font (Fig. 25). The style of letters and numbers of the drawing font is established by the standard. The standard defines the height and width of letters and numbers, the thickness of stroke lines, the spacing between letters, words, and lines.

Rice. 25. Inscriptions on drawings

An example of building one of the letters in the auxiliary grid is shown in Figure 26.

Rice. 26. An example of building a letter

The font can be both slanted (about 75°) and non-slanted.

The standard specifies the following font sizes: 1.8 (not recommended, but allowed); 2.5; 3.5; 5; 7; ten; fourteen; 20; 28; 40. The size (h) of the font is taken as the value determined by the height of uppercase (capital) letters in millimeters. The height of the letter is measured perpendicular to the base of the line. The lower elements of the letters D, C, U and the upper element of the letter Y are performed due to the spaces between the lines.

The thickness (d) of the font line is determined depending on the height of the font. It is equal to 0.1h;. The width (g) of the letter is chosen to be 0.6h or 6d. The width of the letters A, D, Zh, M, F, X, C, SH, W, b, Y, Yu is 1 or 2d more than this value (including the lower and upper elements), and the width of the letters Г, 3, С is less than d.

The height of the lowercase letters roughly matches the height of the next smaller font size. Thus, the height of lowercase letters of size 10 is 7, of size 7 is 5, and so on. The width of most lowercase letters is 5d. The width of the letters a, m, c, b is 6d, the width of the letters w, t, f, w, u, s, u is 7d, and the letters h, c are 4d.

The distance between letters and numbers in words is taken equal to 0.2h or 2d, between words and numbers -0.6h or 6d. The distance between the lower lines of the lines is taken equal to 1.7h or 17d.

The standard also establishes another type of font - type A, narrower than just considered.

The height of letters and numbers in pencil drawings must be at least 3.5 mm.

The outline of the Latin alphabet according to GOST is shown in Figure 27.

Rice. 27. Latin script

How to write in cursive font. It is necessary to draw up drawings with inscriptions carefully. Indistinctly made inscriptions or carelessly applied figures of different numbers can be misunderstood when reading the drawing.

To learn how to write beautifully in a drawing font, first a grid is drawn for each letter (Fig. 28). After mastering the skills of writing letters and numbers, you can only draw the top and bottom lines of the line.

Rice. 28. Examples of inscriptions in drawing font

The contours of the letters are outlined with thin lines. After making sure that the letters are written correctly, circle them with a soft pencil.

For the letters G, D, I, I, L, M, P, T, X, C, W, W, only two auxiliary lines can be drawn at a distance equal to their height A.

For letters B, C, E, N. R, U, H, b, Y, b. Between two horizontal lines, one more should be added in the middle, but with which their middle elements perform. And for the letters 3, O, F, Yu, four lines are drawn, where the middle lines indicate the boundaries of the fillets.

To quickly make inscriptions in a drawing font, various stencils are sometimes used. You will fill in the main inscription in font 3.5, the name of the drawing in font 7 or 5.

1. What is the font size?
2. What is the width of the capital letters?
3. What is the height of lowercase letters of size 14? What is their width?

1. Complete a few inscriptions in the workbook for the teacher's assignment. You can, for example, write your last name, first name, home address.
2. Fill in the main inscription on the sheet of graphic work No. 1 with the following text: drew (last name), checked (name of the teacher), school, class, drawing No. 1, the name of the work "Lines".

2.5. How to measure. To determine the size of the depicted product or any part of it, dimensions are applied to the drawing. Dimensions are divided into linear and angular. Linear dimensions characterize the length, width, thickness, height, diameter or radius of the measured part of the product. The angular dimension characterizes the magnitude of the angle.

The linear dimensions in the drawings are indicated in millimeters, but the designation of the unit of measure is not applied. Angular dimensions are indicated in degrees, minutes and seconds with the designation of the unit of measurement.

The total number of dimensions in the drawing should be the smallest, but sufficient for the manufacture and control of the product.

The rules for sizing are set by the standard. Some of them you already know. Let's remind them.

1. Dimensions in the drawings are indicated by dimensional numbers and dimension lines. To do this, first draw extension lines perpendicular to the segment, the size of which is indicated (Fig. 29, a). Then, at a distance of at least 10 mm from the contour of the part, a dimension line parallel to it is drawn. The dimension line is limited on both sides by arrows. What should be the arrow is shown in Figure 29, b. The extension lines extend beyond the ends of the arrows of the dimension line by 1...5 mm. Extension and dimension lines are drawn with a solid thin line. Above the dimension line, closer to its middle, a dimension number is applied.

Rice. 29. Drawing linear dimensions

2. If there are several dimension lines parallel to each other in the drawing, then a smaller size is applied closer to the image. So, in Figure 29, first the size 5 is applied, and then 26, so that the extension and dimension lines in the drawing do not intersect. The distance between parallel dimension lines must be at least 7 mm.

3. To indicate the diameter, a special sign is applied in front of the dimension number - a circle crossed out with a line (Fig. 30). If the dimension number does not fit inside the circle, it is taken out of the circle, as shown in Figure 30, c and d. The same is done when applying the size of a straight segment (see Fig. 29, c).

Rice. 30. Applying the size of circles

4. To designate the radius, a capital Latin letter R is written in front of the dimension number (Fig. 31, a). The dimension line to indicate the radius is drawn, as a rule, from the center of the arc and ends with an arrow on one side, resting on the point of the circular arc.

Rice. 31. Dimensioning Arcs and Angle

5. When specifying the size of the corner, the dimension line is drawn in the form of an arc of a circle with the center at the apex of the corner (Fig. 31, b).

6. Before the dimension number indicating the side of the square element, a "square" sign is applied (Fig. 32). In this case, the height of the sign is equal to the height of the digits.

Rice. 32. Drawing the size of the square

7. If the dimension line is located vertically or obliquely, then the dimension numbers are arranged as shown in Figures 29, c; thirty; 31.

8. If the part has several identical elements, then it is recommended to put the size of only one of them on the drawing, indicating the quantity. For example, the entry in the drawing “3 holes. 0 10" means that the part has three identical holes with a diameter of 10 mm.

9. When depicting flat parts in one projection, the thickness of the part is indicated, as shown in Figure 29, c. Please note that in front of the dimension number indicating the thickness of the part, there is a small Latin letter 5.

10. It is allowed to indicate the length of the part in a similar way (Fig. 33), but in this case they write a Latin letter before the size number l.

Rice. 33. Drawing the size of the length of the part

1. In what units are linear dimensions expressed on engineering drawings?
2. How thick should extension and dimension lines be?
3. What distance is left between the image outline and the dimension lines? between dimension lines?
4. How are dimensional numbers applied on inclined dimension lines?
5. What signs and letters are applied before the size number when indicating the size of diameters and radii?

Rice. 34. Task for exercises

1. Redraw in a workbook, maintaining proportions, the image of the part given in Figure 34, increasing it by 2 times. Apply the required dimensions, indicate the thickness of the part (it is 4 mm).
2. Draw circles in the workbook with diameters of 40, 30, 20 and 10 mm. Enter their dimensions. Draw circular arcs with radii of 40, 30, 20 and 10 mm and dimension.

2.6. Scales. In practice, it is necessary to make images of very large parts, for example, parts of an aircraft, a ship, a car, and very small ones - parts of a clock mechanism, some instruments, etc. Images of large parts may not fit on sheets of a standard format. Small details that are barely visible to the naked eye cannot be drawn in full size with the available drawing tools. Therefore, when drawing large parts, their image is reduced, and small ones are increased compared to the actual dimensions.

Scale is the ratio of the linear dimensions of the image of an object to the actual. The scale of the images and their designation in the drawings sets the standard.

Reduction scale-1:2; 1:2.5; 1:4; 1:5; 1:10 etc.
Natural size-1:1.
Magnification scale-2:1; 2.5:1; 4:1; 5:1; 10:1 etc.

The most desirable scale is 1:1. In this case, you do not need to recalculate the dimensions when rendering the image.

Scales are written as follows: M1:1; M1:2; M5:1, etc. If the scale is indicated on the drawing in the main inscription specially designed for this, then the letter M is not written before the scale designation.

It should be remembered that, no matter what scale the image is made, the dimensions in the drawing are applied to the actual ones, that is, those that the part should have in kind (Fig. 35).

The angular dimensions do not change when the image is reduced or enlarged.

1. What is the scale for?
2. What is called scale?
3. What scales of increase are known to you, established by the standard? What scale of reduction do you know?
4. What do the entries mean: М1:5; M1:1; M10:1?

Rice. 35. Drawing gasket, made in different scales

Graphic Work No. 2
Drawing "flat part"

Make drawings of the “Gasket” parts according to the existing halves of the images separated by the axis of symmetry (Fig. 36). Apply dimensions, indicate the thickness of the part (5 mm).

Do the work on an A4 sheet. Image scale 2:1.

Instructions for work. Figure 36 shows only half of the part image. You need to imagine how the part will look like in full, keeping in mind the symmetry, sketch its image on a separate sheet. Then you should proceed to the execution of the drawing.

A frame is drawn on an A4 sheet and space is allocated for the main inscription (22X145 mm). The center of the working field of the drawing is determined and the image is built from it.

First, axes of symmetry are drawn, a rectangle is built with thin lines, corresponding to the general shape of the part. After that, images of rectangular elements of the part are marked.

Rice. 36. Tasks for graphic work No. 2

Having determined the position of the centers of the circle and the semicircle, they are carried out. Apply the dimensions of the elements and overall, i.e., the largest in length and height, the dimensions of the part, indicate its thickness.

Outline the drawing with lines established by the standard: first - circles, then - horizontal and vertical lines. Fill in the main inscription and check the drawing.

Topic: Graphic work No. 2 "Drawing of a flat part"

1. Goals and objectives:

Target: To acquaint students with the topic "Drawing of a flat part, symmetrical about one plane of symmetry."

Tasks: 1 DEVELOPING : development of creative thinking.

2 EDUCATIONAL: the formation of independence, accuracy.

3 EDUCATIONAL: teach how to correctly place parts on a format, apply dimensions to drawings.

1. Lesson type: combined.
2. Equipment: drawing tools, notebook, textbook, educational multimedia tables.
3. Lesson plan:

1. Org. moment.
2. Checking homework.
3. Theoretical part.
4. Practical part.
5. House. exercise.
6. Summary of the lesson.

During the classes:

Knowledge check:

Front work:

1) remember the types of lines and their style.

2) I ask questions on the subject of sizing.

3) work on the cards "Find the mistake"

Several students work at the blackboard (finish the drawing with the missing lines, build a 3rd projection according to the 2nd data, correctly apply dimensions), several students work at their workplaces.

Theoretical part:

Part construction algorithm: APPENDIX (multimedia)

1. Analysis of the geometric shape and symmetry of the part.
2. Establishment of the main view, analysis of its graphic composition, for example: a rectangle has rectangular cutouts, in the center there is a circle. The image is symmetrical about one axis of symmetry.
3. Selecting the position of the format: if the length is greater than the height, then - horizontally; if the height is greater than the length, then - vertically.
4. Choice of image scale.
5. Definition of the working area of ​​the drawing.
6. Compositional solution of the drawing:

1. holding the vertical axis of symmetry.
2. calculation of the placement of the overall rectangle according to the height of the working field according to the formula

1. construction of a dimensional rectangle.

1. Markup and image construction:

1. Refinement of the outer outline of the part contour.
2. Refinement of the inner contour of the part.

1. Dimensioning in length, height and thickness (overall dimensions)
2. Stroke: circles, horizontal lines, vertical, slanted. Filling in the main inscription on the drawing.

Practical part:

Task cards

Homework:

Pages 30-31, figure 36 (a, b)

Lesson summary:

1. What did you learn new?

2. What practical skills have been consolidated.

3. What new practical skills have you acquired.

4. What did you succeed in the lesson?

5. What else needs to be worked on.

6. Analysis and results, evaluate the work of students.

Preview:

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Slides captions:

Drawing of a “flat” part, symmetrical with respect to one plane of symmetry Construction algorithm

1. Analysis of the geometric shape and symmetry of the part.

2. Establishment of the main view, analysis of its graphic composition, for example: a rectangle has rectangular cutouts, in the center there is a circle. The image is symmetrical about one axis of symmetry. Circles

3. Selecting the position of the format: if the length is greater than the height, then - horizontally; if the height is greater than the length, then - vertically. 50 120

4. Choice of image scale. 5. Definition of the working field of the drawing. Working field

6. Compositional solution of the drawing: a. holding the vertical axis of symmetry. b. calculation of the placement of the overall rectangle according to the height of the working field according to the formula c. construction of a dimensional rectangle. L working field N N h det.

7. Markup and construction of the image: a. refinement of the outer contour of the part. b. refinement of the inner contour of the part.

8. Drawing dimensions along the length, height and thickness. S

Stroke: circles, horizontal lines, vertical, slanted. Filling in the title block. S

On fig. 37 shows an example of a variant of the task for performing the calculation and graphic work "Projection drawing", as well as a visual image of a given part with a cutout.

The drawing of the part made according to this task in three projections with correctly formatted dimensions is shown in Fig. 38. This example will help students understand their assignment, start doing graphic work and avoid numerous mistakes in its design.

Recall that in the task there are only two projections of the part, therefore the dimensions are distributed on two images. However, when drawing up a drawing, dimensions should be applied evenly on all three projections.

In conclusion, it should be noted that the number of images of a part (views, sections, sections) should be the smallest, but providing a complete picture of its design when using the established relevant standards for symbols, signs and inscriptions.

Literature

Popova G.N., Alekseeva S.Yu. Engineering drawing: a Handbook. -L.: Mashinostroyeniye, Leningrad. department, 1986.

Levitsky V.S. Mechanical engineering drawing. - M.: Higher School, 1988.

Gordon V.O., Sementsov-Ogievsky N.A. Descriptive geometry course. - M.: Nauka, 1994.

Frolov S.A. Descriptive geometry. - M.: Mashinostroenie, 1978.

Appendix. Task options for settlement and graphic work

Task options for settlement and graphic work on the topic "Projection drawing" are given in Table. P1. The rules for choosing a task option are determined by the teacher.

Table P1. Task options for the RGR on the topic "Projection drawing"