Discipline engineering graphics is usually studied at universities
1st or 2nd year, depending on the specialization and form of study.
The content of engineering graphics assignments may be different,
depends on the specific specialty and course you are studying. Typical engineering graphics work is:
- drawing dimensions and maximum deviations;
- construction of the third type of part in the drawing according to two given ones;
- sections, sections, local views;
- axonometric projections (isometry and dimetry);
- preparation of specifications, detailing, assembly drawings;
- making sketches of parts.
And also other works.
Engineering graphics - execution of drawings
We offer production of drawings on the subject of engineering graphics. Drawings are made in Compass and AutoCAD programs. Drawings can also be made by hand, on whatman paper or graph paper, depending on the requirements for the drawings. Drawings made on paper are sent by mail. Delivery times vary depending on your location.
The timing for the production of drawings according to engineering graphics depends on the method of execution (by hand or electronically), as well as the volume of work. The lead time for drawings in Compass and AutoCAD is naturally shorter than for drawings by hand. Therefore, if possible, order drawings electronically. They take less time to complete, and therefore the price will be lower than hand drawings. Nowadays, more and more often, universities allow the execution of drawings in the subject of engineering graphics in electronic form. But not everywhere and not always, so before placing an order for work, be sure to check with the teacher in what form the completed task can be provided.
All work on engineering graphics is carried out in accordance with GOST and ESKD.
Engineering graphics - prices for drawings, works
Prices for drawings for the subject of engineering graphics depend on the complexity and number of drawings. An approximate guide to the cost of work can be the sheet format. Submit your order using the form on the page. After which you will receive an answer indicating the cost of the work in a response letter. If the price suits you, you will confirm the order.
Examples of engineering drawings
This page contains just a few examples of engineering graphics drawings. More examples can be found in the section on the page.
Work on engineering graphics. The task was completed in the Compass program. A3 sheet format.
Exercise. Construction of a complex drawing of a part based on a visual image (axonometric projection). Making cuts. Applying dimensions.
Execution of the drawing. Above is a finished drawing based on engineering graphics. To enlarge, hover over it and click once.
. Assembly drawing of a sliding prism. The drawing was made in the AutoCAD program.
Gradually, the list of examples of engineering graphics drawings will increase.
Contacts .
1.1 Formats
Drawings are made on sheets of a certain format (size).
Sheet formats are determined by the dimensions of the outer drawing frame, drawn with a thin line.
According to GOST 2.301-68*, the dimensions of the main formats are obtained by sequentially dividing the A0 format, with side dimensions of 841x1189 mm, the area of which is 1 m2, into two equal parts parallel to the smaller side (Figure 1.1). The number in the designation shows how many times this action was performed.
The designations and sizes of the main formats must correspond to those indicated in Table 1.
Table 1 - Main formats
Format designation | A0 | A1 | A2 | A3 | A4 |
---|---|---|---|---|---|
Dimensions of format sides, mm | 841x1189 | 594x841 | 420 x594 | 297 x420 | 210 x297 |
It is allowed to use additional formats formed by increasing the sides of the main formats by an amount that is a multiple of their sizes. In this case, the magnification factor must be an integer.
The sizes of derived formats, as a rule, should be selected from Table 2. The designation of the derived format is made up of the designation of the main format and its multiplicity according to the data in Table 2: for example, A0x2, A4x8, etc.
Table 2 - Additional formats
Multiplicity | A0 | A1 | A2 | A3 | A4 |
---|---|---|---|---|---|
2 | 1189*1682 | — | — | — | — |
3 | 1189*2523 | 841*1783 | 594*1261 | 420*891 | 297*630 |
4 | — | 841*2378 | 594*1682 | 420*1189 | 297*841 |
5 | — | — | 594*2102 | 420*1486 | 297*1051 |
6 | — | — | — | 420*1783 | 297*1261 |
7 | — | — | — | 420*2080 | 297*1471 |
8 | — | — | — | — | 297*1682 |
9 | — | — | — | — | 297*1892 |
1.2 Scale
Scale is the ratio of the linear dimensions of the image of an object in the drawing to the actual dimensions of this object.
The scale indicated in the designated column of the title block of the drawing should be indicated as 1:1, 2:1, etc., and in other cases - as (1:1), (1:2), (2 :1) etc. (Table 3).
According to GOST 2.302 - 68*, the scales of images in the drawings must be selected from the following row - Table 3.
Table 3- Scales
1.3 Lines
To depict objects in drawings, GOST 2.303 – 68* establishes the style, thickness and main purposes of lines in the drawing (Table 4).
Solid base line thickness S should be between 0,5 before 1.4 mm depending on the size and complexity of the image, as well as the format of the drawing. The thickness of lines of the same type should be the same for all images in a given drawing, drawn to the same scale.
The length of the strokes of the dashed lines should be approximately 10 times the thickness of the stroke, and the length of the strokes of the dash-dotted line is selected depending on the size of the image. The strokes in the line should be approximately the same length. The spaces between them should also be approximately the same. The dash-dot lines must intersect and end in dashes. Dot-dash lines used as center lines should be replaced with solid thin lines if the diameter of the circle or the size of other geometric shapes in the image is less than 12 mm.
Table 4 - Lines
Name | Typeface | Line thickness in relation to the main line thickness | Main purpose |
---|---|---|---|
S | Visible contour lines, visible transition lines, section contour lines. | ||
From S/3 before S/2 | Contour lines of an overlaid section, dimension and extension lines, hatch lines, leader lines, leader line flanges | ||
From S/3 before S/2 | Break lines, view and section demarcation lines | ||
From S/3 before S/2 | Invisible contour lines, invisible transition lines | ||
From S/3 before S/2 | Axial and center lines, section lines, which are axes of symmetry for superimposed or extended sections. | ||
From S/2 before 2/3*S | Lines indicating surfaces to be heat treated or coated | ||
From S before 1.5*S | Section lines | ||
From S/3 before S/2 | Long break lines | ||
From S/3 before S/2 | Fold lines on developments, lines for depicting parts of products in extreme or intermediate positions, lines for depicting a development combined with the view. |
1.4 Title block
The drawing is drawn up with a frame, which is drawn as a solid main line at a distance of 5 mm from the right, bottom and top sides of the outer frame of the drawing. A 20 mm wide margin is left on the left side, which is used for filing and binding drawings (Figure 1.2).
The main inscription is placed in the lower right corner of the design documents. On A4 sheets the main inscription is placed along the short side of the sheet, on sheets of A3 and larger format it is allowed to place the main inscription along both the long and short sides of the sheet. The main inscriptions and additional columns to them are made with solid main and solid thin lines in accordance with GOST 2.303 - 68* (Figure 1.3).
The main inscription according to Form 1 is used in instrument and mechanical engineering drawings.
The main inscription according to Form 2 is used in specifications and other text documents - the first sheet, according to Form 3 - subsequent sheets.
form 1
form 2
form 2a
In the columns of the main inscription indicate:
- in column 1 - name of the product;
- in column 2 - designation of the document;
- in column 3 - designation of the material of the part;
- in column 4 - the letter assigned to this document;
- in column 5 - the mass of the product;
- in column 6 - scale;
- in column 7 - the serial number of the sheet (on documents consisting of one sheet, the column is not filled in);
- in column 8 - the total number of sheets of the document (the column is filled out only on the first sheet);
- in column 9 - the name of the enterprise issuing the document;
- in column 10 - the functions of the performers are indicated: “Developed”, “Checked”;
- in column 11 - the names of the persons who signed the document;
- in column 12 - signatures of persons whose surnames are indicated in column 11;
- in column 13 - date;
- Columns 14-18 are filled in on production drawings.
1.5. Fonts
GOST 2.304-81* defines the style, dimensions and rules for making inscriptions on drawings and other design documents.
The inclination of letters and numbers to the base of the line should be about 75°.
Font size ( h)- a value equal to the height of capital letters in mm.
Capital letter height h measured perpendicular to the base of the line. The height of lowercase letters c is determined from the ratio of their heights (without branches k) to font size h, For example, с=7/10*h.
Letter width ( q)- the greatest width of a letter is determined in relation to the font size h, For example, q=6/10 h, or in relation to the line thickness of the font d, For example, q=6d.
Font line thickness ( d)- thickness, determined depending on the type and height of the font.
Auxiliary grid - a grid formed by auxiliary lines into which letters fit. The pitch of the auxiliary grid lines is determined depending on the thickness of the font lines d(Figure 1.4).
When preparing drawings and other design documents, it is recommended to use type B font with a slope of 75° ( d=1/10h) with the parameters given in Table 5.
Table 5 - Fonts
Font options | Designation | Relative size | Dimensions | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Font size - height of capital letters | h | (10/10)h | 10d | 1,8 | 2,5 | 3,5 | 5,0 | 7,0 | 10,0 | 14,0 | 20,0 |
Height of lowercase letters | c | (7/10)h | 7d | 1,3 | 1,8 | 2,5 | 3,5 | 5,0 | 7,0 | 10,0 | 14,0 |
Letter spacing | a | (2/10)h | 2d | 0,35 | 0,5 | 0,7 | 1,0 | 1,4 | 2,0 | 2,8 | 4,0 |
Minimum row pitch (height, auxiliary grid) | b | (17/10)h | 17d | 3,1 | 4,3 | 6,0 | 8,5 | 12,0 | 17,0 | 24,0 | 34,0 |
Minimum distance between words | e | (6/10)h | 6d | 1,1 | 1,5 | 2,1 | 3,0 | 4,2 | 6,0 | 8,4 | 12,0 |
Font line thickness | d | (1/10)h | d | 0,18 | 0,25 | 0,35 | 0,5 | 0,7 | 1,0 | 1,4 | 2,0 |
The following font sizes are set: (1.8); 2.5; 3.5; 5; 7; 10; 14; 20; 28; 40.
For questions regarding tutoring in engineering graphics (drawing), you can contact us in any way convenient for you in the section Contacts . Full-time and distance learning via Skype is possible: RUB 1,000/academic hour.
MINISTRY OF TRANSPORT OF THE RUSSIAN FEDERATION FEDERAL STATE EDUCATIONAL INSTITUTION OF HIGHER PROFESSIONAL EDUCATION
MOSCOW STATE TECHNICAL UNIVERSITY OF CIVIL AVIATION
____________________________________________________________________________________________________________________
Department of Descriptive Geometry and Graphics
HE. Pachkoria, I.V. Podzey, N.N. Medvedeva, M.V. Semakova
ENGINEERING GRAPHICS
GUIDE to making drawings of parts
according to the general view drawing of the assembly unit
for first year students of specialty 131000, 130300, 201300, 330500
full-time education
Moscow - 2003
general view drawing of the assembly unit. – M.: MSTU GA, 2003. – 68 p. This manual is published in accordance with the curriculum for first-year students of specialties 130300, 131000, 201300, 330500 full-time study. Reviewed and approved at department meetings on August 28, 2003. and methodological council 09/23/03.
Editor I.V. Vilkova
Moscow State Technical University of Civil Aviation
125993 Moscow, Kronstadtsky Boulevard, 20
Editorial and publishing department
125493 Moscow, st. Pulkovskaya, 6a
© Moscow State Technical University of Civil Aviation, 2003
1. Basic provisions
IN training course in engineering graphics, making drawings of a part based on a general view drawing of an assembly unit is called detailing. In an engineering graphics course, detailing is the culminating activity of the discipline. Detailing can be successfully performed only on the basis of knowledge of the projection method, familiarity with structures and drawings (sketches) of real machine parts, and the features of making a general view drawing of an assembly unit, studied earlier in the engineering graphics course. .
TO Design documents for any created product include graphic and text documents that, individually or collectively, determine the composition and structure of the product and contain the necessary data for its design or manufacture, control, operation and repair.
The individual assignment that the student receives consists of a drawing of the general view of the product and a table of components placed on one sheet with an image of the product. Based on this drawing, it is necessary to make drawings of the specified parts. Instead of general view drawings, it is possible to use educational assembly drawings.
The skills acquired by students in the process of making working drawings of parts are necessary for them in the future when completing coursework and diploma projects.
Purpose of work: acquiring knowledge and skills in reading a drawing of an assembly unit and making drawings of parts.
2. Contents of the working drawing of the part
Working drawing of the part is a design document containing an image of the part and other data necessary for its manufacture and control.
The working drawing must contain:
a minimum but sufficient number of images (views, sections, sections, extensions) that fully reveal the shape of the part
required dimensions with their maximum deviations
surface roughness
information about material, heat treatment, coating, finishing
technical requirements
3. Basic requirements for the execution of drawings of parts
The basic requirements for the execution of drawings of parts are established by GOST 2.109-73:
1. Each detail drawing is performed in a separate format according to GOST 2.301-68
2. The drawing must contain the main inscription, which is located in the lower right corner of each format according to GOST 2.104-68 (form 1). For all formats,
With the exception of A4 format, the main inscription can be located either along the long or short side. On A4 format, the main inscription should be placed only along the short side (Fig. 115-117). The designation of the drawing is applied in font No. 10. The name of the part and its material is written in the nominative singular case, starting with the noun, for example, “Gear wheel” (Fig. 116).
3. In the drawings, symbols are used (lines, signs, letters and alphanumeric designations) established by state standards. GOST 2.303-68, GOS 2.304-81, GOST 2.307-68
4. Material grades are designated in accordance with the designations assigned to them in the standards
5. The image scale is chosen in accordance with GOST 2.302-68
6. Dimensions are indicated according to State Standards 2.307-68
In the working drawing, the part is depicted with the dimensions and parameters that it should have before assembly. Based on such drawings, the entire technological process of manufacturing a part is developed and technological maps are drawn up, on which the part is depicted in intermediate stages of manufacturing.
Working drawings must be graphically designed in accordance with the requirements of the ESKD. On educational working drawings in the Engineering Graphics course, students do not indicate:
surface roughness
designation of maximum deviations of the shape and location of surfaces
When manufacturing an assembly unit, individual parts are connected to each other using assembly operations.
4. Reading the general view drawing.
Let's remember the basic definitions.
A part is a product made from a material of the same name and brand, without the use of assembly operations, for example: a roller made of one piece of metal; welded tube from one piece of sheet material.
Parts are divided into original; original, but containing standardized elements, and standard.
Assembly unit is a product whose components are to be connected to each other at the manufacturing plant by assembly operations (screwing, joining, riveting, welding, soldering, crimping, flaring, gluing, etc.).
General view drawing (code VO) defines the design of the product, the interaction of its components and explains the principle of operation of the product (compiled, as a rule, during the development of preliminary and technical designs).
Assembly drawing (code SB) contains an image of the assembly unit and other data necessary for its assembly and control.
Before you begin making working drawings of parts, you must read the general view drawing.
1. Familiarization with the content of the title block to determine: product name, image scale, artist, etc.
2. Establishing the purpose and principle of operation of the product, its technical characteristics and operating requirements according to the documents attached to the drawing (in training drawings such documents are shown in the field of the general view drawing).
3. Determination according to the specification of the quantity and name of original, standardized and purchased parts included in the product.
4. General familiarization with images of the product and establishment of the number and variety of images (views, sections, sections, extensions, connections of views with sections, etc.), determination of the positions of the cutting planes with the help of which the cuts and sections are made. Attention is drawn to the inscriptions and symbols above the images.
5. Clarification of overall, installation, installation, characteristic and reference dimensions marked on the drawing.
6. Establishing the nature of the interaction of the component parts of the product, its functional features and relationships with other products, as well as the nature of the connections (detachable or permanent).
7. Studying the shape and position of a specific part. Determination of its number in the assembly unit, comparison with the position number assigned to the part according to the specification. When studying the shape and position of a specific part, the overall design of the assembly unit and the projection relationship of the images should be taken into account.
8. Finding out how the part is made.
4.1. Features of reading a general view drawing
It is very difficult to determine the design of an assembly unit from a general drawing without a complete analysis of the configuration of each of its parts. In a general view drawing, the parts are shown connected and partially covering each other. In Fig. 1, a. shows a fragment of an assembly unit, which includes a part of the “Clamp” type. In Fig. 1,b is a drawing of the “Clamp” part.
When reading a general view drawing of an assembly unit, it is necessary to analyze all the images on it, i.e. find images of the same thing in different images
And the same detail. This can be done using the following principles:
Existing projection connection on all sections and sections between images
Hatching for one part has the same parameters (inclination and hatching pitch)
Another feature of reading a general view drawing is the presence in it of simplifications for some elements of the parts. However, when performing working drawings of these parts, they
the design must be fully reflected without simplifications, for example, technological thread elements, Fig. 2 and fig. 3
On the general drawing
On working drawings of parts
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4.1.1. Some conventions and simplifications in assembly drawings
1. It is allowed not to show on assembly drawings:
chamfers, fillets, roundings, grooves, recesses, protrusions, knurls, notches, braids and other small elements; rice. 6-8.
gaps between the rod and the hole; rice. 8
covers, shields, casings, partitions, etc., if it is necessary to show the components of the product covered by them. In this case, an appropriate inscription is made above the image, for example, “Cover pos. 3 not shown”;
patterned curved transition lines, replacing them with circular arcs or straight lines;
visible components of products or their elements located behind the mesh, as well as partially covered by components located in front;
2. Products made from transparent material are depicted as opaque. It is allowed to depict components of products and their elements located behind transparent objects as visible, for example, scales, instrument needles, etc..3. 3. Products located behind the helical spring, depicted only by the sections of the coils, are depicted up to the zone that conventionally covers these products and is defined by the axial lines of the sections of the coils, Fig. 6
3. In cases where there is no need to depict individual fasteners or their connections in accordance with the relevant standards on assembly drawings, they are depicted simplified or conventionally according to GOST 2.315-68., fig. 4, 8, 101, 102, 104.
4. If the product shown in the assembly drawing has several similar connections, for example, with bolts or studs, then in the views and sections these connections are made conditionally or simplified only in one or two places of each connection, and the rest - in the form of axial and center lines.
5. A welded, soldered, glued product made of a homogeneous material assembled with other products in sections and sections is hatched in one direction, depicting the boundaries between the parts of the product with solid main lines. It is allowed not to show the boundaries between parts, depicting the structure as a monolithic body.
Rice. 4 Figure 5, 6 shows an example of a training assembly drawing with a specification, and
Figure 7 shows the elements of parts that are made on working drawings without simplifications: chamfers, grooves (without an extension element and with an extension element). Particular attention should be paid to the equality of the associated dimensions of the parts.
Assembly units |
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1. Rules for drawing up drawings 1.1. The concept of ESKD standards. If each engineer or draftsman executed and designed drawings in his own way, without following the same rules, then such drawings would not be understandable to others. To avoid this, the USSR adopted and operates state standards of the Unified System of Design Documentation (ESKD). 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 established 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 along with 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 title “Drawings for all types of mechanical engineering.” Later they were replaced with new ones. 1.2. Formats. The main inscription of the drawing. Drawings and other design documents for industry and construction are performed on sheets of certain sizes. For economical use of paper, ease of storage and use of drawings, the standard establishes certain sheet formats, which are outlined with a thin line. At school you will use a format whose sides measure 297X210 mm. It is designated A4. Each drawing must have a frame that limits its field (Fig. 18). The frame lines are solid thick basic ones. They are carried out from above, to the right and below at a distance of 5 mm from the outer frame, made by a continuous 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. Design of A4 sheet On the drawings, the main inscription is placed in the lower right corner (see Fig. 18). Its shape, size and content are established by the standard. On educational school drawings you will make the main inscription in the form of a rectangle with sides 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 educational drawing Production drawings made on A4 sheets are placed only vertically, and the main inscription on them is only along the short side. On drawings of other formats, the title block can be placed along both the long and short sides. As an exception, on educational drawings in A4 format, the main inscription is allowed to be placed both along the long and short sides 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 crossbar is placed on the board and the upper edge of the sheet is placed parallel to its edge, as shown in Figure 20. Pressing the sheet of paper to the board, attach it with buttons, first in the lower right corner, and then in the remaining corners. Rice. 20. Preparing the sheet for work The frame and columns of the main inscription are made with a solid thick line.
1.3. 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 part drawing contains different lines. In order for the image to be clear to everyone, the state standard establishes the outline of lines and indicates their main purpose for all industrial and construction drawings. In technical and maintenance lessons you have already used various lines. Let's remember them. In conclusion, the thickness of lines of the same type should be the same for all images in a given drawing. Information about the drawing lines is given on the first flyleaf.
In Figure 23 you see an image of the part. Various lines are marked on it with numbers 1,2, etc. Make a table based on this example in your workbook and fill it out. Rice. 23. Exercise task EXAMPLE No. 1 Prepare a sheet of A4 drawing paper. Draw the frame and columns of the main inscription according to the dimensions indicated in Figure 19. Draw various lines, as shown in Figure 24. You can choose another arrangement of groups of lines on the sheet. Rice. 24. example No. 1 The main inscription can be placed both along the short and along the long side of the sheet. 1.4. Drawing fonts. Sizes of letters and numbers of a drawing font. All inscriptions on the drawings must be made in drawing font (Fig. 25). The style of letters and numbers of a drawing font is established by the standard. The standard determines the height and width of letters and numbers, the thickness of stroke lines, the distance between letters, words and lines. Rice. 25. Inscriptions on drawings An example of constructing one of the letters in the auxiliary grid is shown in Figure 26. Rice. 26. Example of letter construction The font can be either slanted (about 75°) or without slanting. The standard sets the following font sizes: 1.8 (not recommended, but allowed); 2.5; 3.5; 5; 7; 10; 14; 20; 28; 40. The size (h) of a font is taken to be the value determined by the height of 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, Ts, Shch and the upper element of the letter Y are made 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, Ж, М, Ф, X, Ц, Ш, Ш, Ъ, ы, У is greater than this value by 1 or 2d (including the lower and upper elements), and the width of the letters Г, 3, С is less by d. The height of lowercase letters is approximately the same as the height of the next smaller font size. So, the height of lowercase letters of size 10 is 7, size 7 is 5, etc. The upper and lower elements of lowercase letters are made due to the distances between the lines and extend beyond the line in 3d. Most lowercase letters are 5d wide. The width of the letters a, m, c, ъ is 6d, the letters zh, t, f, w, shch, s, yu are 7d, and the letters z, s are 4d. The distance between letters and numbers in words is taken to be 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 the one just discussed. The height of letters and numbers in pencil drawings must be at least 3.5 mm. The layout of the Latin alphabet according to GOST is shown in Figure 27. Rice. 27. Latin font How to write in drawing font. It is necessary to draw up drawings with inscriptions carefully. Poorly written inscriptions or carelessly applied digits of different numbers may be misunderstood when reading the drawing. To learn how to write beautifully in a drawing font, first draw a grid 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 making inscriptions in drawing font The outlines of the letters are outlined with thin lines. After making sure that the letters are written correctly, trace them with a soft pencil. For the letters G, D, I, Ya, L, M, P, T, X, C, Ш, Ш, you can only draw two auxiliary lines at a distance equal to their height A. For the letters B, V, E, N. R, U, CH, Ъ, И, ь. Between the two horizontal lines, another one should be added in the middle, but which is filled with their middle elements. And for the letters 3, O, F, Yu, four lines are drawn, where the middle lines indicate the boundaries of the roundings. To quickly write inscriptions in a drawing font, various stencils are sometimes used. You will fill out the main inscription in 3.5 font, the title of the drawing in 7 or 5 font.
1.5. How to apply dimensions. 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. Angular size characterizes the size of the angle. Linear dimensions in the drawings are indicated in millimeters, but the unit of measurement is not indicated. 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 applying dimensions are established by the standard. You already know some of them. Let's remind them. 1. Dimensions in the drawings are indicated by dimensional numbers and dimensional 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, draw a dimension line parallel to it. The dimension line is limited on both sides by arrows. What the arrow should be is shown in Figure 29, b. Extension lines extend beyond the ends of the arrows of the dimension line by 1...5 mm. Extension and dimension lines are drawn as a solid thin line. Above the dimension line, closer to its middle, the dimension number is applied. Rice. 29. Applying linear dimensions 2. If there are several dimension lines parallel to each other in the drawing, then a smaller dimension is applied closer to the image. So, in Figure 29, first dimension 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 size number - a circle crossed out by a line (Fig. 30). If the dimensional number does not fit inside the circle, it is taken outside the circle, as shown in Figure 30, c and d. The same is done when applying the size of a straight segment (see Figure 29, c). Rice. 30. Sizing circles 4. To indicate the radius, write the capital Latin letter R 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, abutting the point of the arc of the circle. Rice. 31. Applying dimensions of arcs and angles 5. When indicating the size of an angle, the dimension line is drawn in the form of a circular arc with the center at the vertex of the angle (Fig. 31, b). 6. Before the dimensional 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 numbers. Rice. 32. Applying the size of the square 7. If the dimension line is located vertically or obliquely, then the dimension numbers are placed as shown in Figure 29, c; thirty; 31. 8. If a part has several identical elements, then it is recommended to indicate on the drawing the size of only one of them with an indication of the quantity. For example, an entry on 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 the dimensional number indicating the thickness of the part is preceded by the Latin small letter 5. 10. It is allowed to indicate the length of the part in a similar way (Fig. 33), but in this case a Latin letter is written before the dimension number l. Rice. 33. Applying the part length dimension
Rice. 34. Exercise task
1.6. Scale. In practice, it is necessary to create images of very large parts, for example parts of an airplane, ship, car, and very small ones - parts of a clock mechanism, some instruments, etc. Images of large parts may not fit on sheets of standard format. Small details that are barely visible to the naked eye cannot be drawn in full size using existing drawing tools. Therefore, when drawing large parts, their image is reduced, and small ones are increased in comparison with the actual dimensions. Scale is the ratio of the linear dimensions of the image of an object to the actual ones. The scale of images and their designation on drawings sets the standard. Reduction scale - 1:2; 1:2.5; 1:4; 1:5; 1:10, etc. The most desirable scale is 1:1. In this case, when creating an image, there is no need to recalculate the dimensions. The scales are written as follows: M1:1; M1:2; M5:1, etc. If the scale is indicated on the drawing in a specially designated column of the main inscription, 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 on the drawing are actual, i.e. those that the part should have in kind (Fig. 35). The angular dimensions do not change when the image is reduced or enlarged.
Rice. 35. Drawing of the gasket, made in various scales EXAMPLE No. 2 |