What determines the number of images of the details. Images - views, sections, sections. What product is called an assembly unit

All visible contours of the product are made in a solid thick - the main line. Depending on the format of the drawing, the size and complexity of the image, the thickness of the main line s  taken from 0.5 to 1.4mm. The thickness of all other types of lines depends on the thickness of the solid thick base line adopted in this drawing. The thickness of the open line should be 1.5 times thicker than the main line, and all other lines should be 2 or 3 times thinner than the main line.

For drawings performed at the student development stage, the thickness of a solid thick line is sufficient to accept from 0.8 to 1 mm.

The thickness and brightness of the lines of the same destination should be the same for all images in the drawing, made at the same scale.

The length of the strokes in the dashed and dash-dotted lines should be chosen depending on the size of the image.

In the dashed line, the stroke length is taken from 2 to 8 mm, the distance between the strokes - from 1 to 2 mm.

Dash-dotted lines should begin, intersect and end with strokes. Strokes and lines should be the same length, and the intervals between the strokes should be the same between themselves. The length of the strokes of the dash-dotted thin line should be from 5 to 30 mm, thickened - from 3 to 8 mm. The intervals between the strokes should be: for dash-dotted thin lines - from 3 to 5 mm, for thickened - from 3 to 4 mm. Dash-dotted lines used as centerlines should be replaced with solid thin lines if the diameter of the circle or the dimensions of other geometric figures in the image is less than 12 mm.

The length of the stroke of the open line should be from 8 to 20 mm.

Drawing fonts

The drawing fonts used for drawing all the inscriptions on drawings and other technical documents are established by GOST 2.304-81.

The drawing font contains Russian, Latin and Greek alphabets, Arabic and Roman numerals, as well as signs.

The following font sizes are set: 2.5; 3.5; five; 7; ten; 14; 20; 28; 40. They are determined by the height h  capital letters in millimeters, measured perpendicular to the bottom of the line. Letter width g  - the maximum width of the letter, which is determined in relation to the font size h, eg, g = 6 / 10h.

The standard establishes the following types of fonts:

type A without slope (thickness of lines of the font d = 1/14 h);

type A with a slope of about 75 ° ( d = 1/14 h);

type B without tilt ( d = 1 / 10h);

type B with a slope of about 75 ° ( d = 1 / 10h) (Fig. 1).

The shape of the letters of the Russian alphabet and Arabic numerals should be the same for the entire inscription. When making drawings in pencil, the recommended height of capital letters and numbers is 5 mm. For various inscriptions on the engineering drawings, it is preferable to use type A with a slope in accordance with Figure 1.

Figure 1 - Type Font Design BUT  and B

Basic inscriptions

All the above information is necessary for the proper design of images and basic inscriptions on the drawings.

The form, size and order of filling in the basic inscriptions in the design documents are determined by GOST 2.104-68.

There are basic inscriptions for drawings and diagrams - form 1 (fig. 2), and basic inscriptions for text documents - form 2 (fig. 3) on the first or title page and form 2a (fig. 4) on subsequent sheets of text documents, and also on subsequent sheets of drawings and diagrams.

In the columns of the main inscription provide the following data.

In column 1 - the name of the product. The name of the product must be short, recorded in the nominative singular. The point at the end of the name is not put. In the name consisting of several words, in the first place put the name of the noun.

In column 2 - the designation of the document. This column is filled at the enterprises according to the requirements of GOST 2.201-80. On educational drawings, the designation sets the appropriate department. Figure 5 shows an example of filling out the main inscription at the Department of Engineering Graphics UGNTU.

In column 3 - the material of the product according to GOST for the material (filled only on the drawings of the part).

In column 4 - put the letter of the drawing assigned to this document. On the training drawings adopted letters at"- training. The letter is placed in the left column.

In column 5 - the mass of the product depicted in the drawing. Mass indicate theoretical or practical in kg.

In column 6 - the scale of the image.

In column 7 - the ordinal number of the sheet. If all the images are made on one sheet, then the column is not filled.

In column 8 - the total number of sheets of the document. The graph is filled only on the first sheet.

In column 9 - the name of the enterprise that produced the drawing.

In column 10 - the nature of the work performed by the person who signed the document.

In column 11 - the names of the persons who signed the document.

In column 12 - the signatures of persons whose names are listed in column 11.

In column 13 - the date of signing the document.

The remaining columns in the training drawings do not fill out.

Figure 2- Title 1 form.

For drawings and diagrams

Figure 3- Title 2.

For text design documents

(first or title page)

Figure 4 - The main inscription form 2a.

For design documents

(subsequent sheets)

Figure 5 - Example of document designation

The main inscription is carried out by the main and continuous thin lines.

Have a main label in the lower right corner of the design documents. On A4 sheets, the main label is placed along the short side of the format, since this format is used only with a vertical arrangement of the long side. In this case, the title block accurately fits into the frame of the working area of ​​the drawing. Sheets of other formats have a long side both horizontally and vertically.

Table 4 - Font sizes and type of letters to fill in the graphs of basic inscriptions

Select the number of images.  It was stated above that the number of images of the object, including the details in the drawing or sketch, should be the smallest, but providing a complete understanding of the subject when using conventions, signs and inscriptions established in the relevant standards. For parts such as rotation bodies, one image is enough (Fig. 15.4, but, b, at, g,  see also fig. 13.31, b; 14.25) on the plane of projections parallel to the axis of the body - of the form ( but, d) cut (b)  with signs 0 in front of the dimensional numbers of diameters. Single image enough also for details like shaft, plugs with a thread with a designation of a thread. For parts such as bodies of revolution with various structural elements, such as holes, cuts, grooves, the main image is supplemented with one or several types, cuts, sections that reveal the shape of these elements, as well as external elements. So, on fig. 15.5 the main image on a plane parallel to the axis of the part is supplemented either by one profile section (a) or one type (b, at). The images of the parts considered earlier are similarly made - see fig. 13.31, a. Explanation of the form of small structural elements with external elements on details such as bodies of revolution, see, for example, in fig. 13.29, b, in, city  The use of several sections to identify structural elements of the shaft, see, for example, in Fig. 13.26. For thin flat parts of any shape, one image is enough. The thickness of the material is indicated on a remote shelf with an indication of the symbol s of thickness in front of its numerical designation (Fig. 15.6). Select the main image of the part.  The main image of the part is chosen taking into account its manufacturing technology. If in the process of manufacturing a part one of its positions is obviously predominant, then on the main image the detail is recommended to be shown in this position. Planks, rulers, rollers, axes, etc., are recommended to be placed horizontally in the drawing, and cases, brackets, etc. - with the base down. As an example, see fig. 13.44 bracket with a cylindrical base with a diameter of 50 mm. The main image, a frontal section along the plane of symmetry of the part, most fully reveals its internal shape. For a full view of the construction of the detail, five images are required. Another example of the frequency adjustment bracket is fig. 15.7. the main thing the image is the most informative, the bracket on it is depicted with the base down. If a detail of a complex structure in the manufacturing process does not have a predominant position, then the main image of such parts is taken as their location in the finished product - the instrument, the machine. Examples of main images of parts with a horizontal axis, see fig. 15.4,15.5. For parts such as pulleys, wheels, gears, the main image is a frontal cut. It is usually performed completely, which facilitates the application of dimensions. Frontal section reveals the outlines of the details, so the front view is not required. Details such as screws (see fig. 14.28), bolts (see fig. 14.22), rollers are made on lathes or automatic machines. Their axis when processing is horizontal. When depicting such parts in the drawing, they also take into account the position in which the largest amount of work is performed on the manufacture of the part, that is, the greatest number of transitions are performed (the transition is the processing of one elementary surface). The choice of format and layout of the drawing. The format of the drawing or sketch is chosen depending on the complexity and size of the part, taking into account the possibility of both increasing the image as compared to in-kind for complex and small ones, and reducing for simple in form and large parts. The images in the drawing should ensure the clarity of all elements of the part. For small parts, parts use remote elements. Before choosing the format of the drawing, carefully analyze the shape of the part and determine the number of required images. They do this by inspecting the details when sketching from life or by mentally presenting its shape according to the drawing of the assembly unit when detailing. On a pre-selected format, a draft of the layout of the drawing is carried out, on which the axial lines and outline contours of all the necessary images are drawn by hand, hatching outlined cuts, marking the areas for dimensioning. Analyze the planned layout in order to identify the possibility of reducing the format of the drawing by reducing the space occupied by simple symmetrical images - the left, right, top, bottom views by performing only half of these images without reducing the clarity of the drawing. This analysis also takes into account the possibility of changing the scale of all images, as well as individual ones, both in the direction of reducing the images and in the direction of increasing. By analysis results make the final decision on the chosen format. An example of the layout of the drawing for the part shown in Fig. 15.8, is resulted on fig. 15.9. The field P between the images is left to be dimensioned, the field TT  above the title block - for technical requirements. Some reduction in the area and complexity of the drawing can be achieved by the image of half of the views on the left and right. However, this does not allow to reduce the format by 2 times, so the right and left views are left full. MACHINE DRAWING The main requirements of ESKD for the design of drawings All drawings must be carried out in strict accordance with the rules established by ESKD. The design of drawings includes standards for formats, scales, lines, drawing fonts, basic inscriptions. Formats When performing drawings for each of them, the main formats established by the standard GOST 2.301-68 are used. The designations and sizes of the sides of the main formats should correspond to the indications in table 1. Table 1 - Formats If necessary, it is allowed to use the A5 format with the side dimensions of 148´210 mm. Inside the outer frame, each drawing is drawn up with the frame of the working field, which is drawn with a solid thick line at a distance of 20 mm from the left side of the format, which is necessary for filing sheets of the design document, and 5 mm from the other three sides of the format. Scale After determining the working field of the drawing, depending on the complexity and size of the product, the image in the drawing is performed in the appropriate scale, established by GOST 2.302-68. Scale- is the ratio of the image size in the drawing to the corresponding actual (natural) dimensions of the product. The scale of the image in the drawings should be selected from the standard range according to table 2. Table 2 - Standard Scale Series The selected scale should provide a clear image of the product and its structural elements. The scale of the images is indicated in the corresponding column of the main inscription of the drawing by type: 1:1; 1:2; 2:1 etc. If the scale of any image in the drawing differs from that indicated in the main inscription, then its designation is placed above the corresponding image by type: M1: 1; M1: 2; M2: 1. Lines To facilitate the reading of the drawings take nine types of lines set GOST 2.303-68. The types of lines and their main purpose are given in table 3. Table 3 - types of lines	Dimensional and remote lines Hatching lines Superimposed contour lines Contour lines, leader shelves and underline labels
Solid wavy		Cliff Lines View and cut demarcation lines
Dashed		Invisible contour lines
Dash-dot thin		Lines axial and centering Lines of sections, which are axes of symmetry for imposed or carried out sections
Dot-dotted thickened		Lines for the image of elements located in front of the secant plane (“superimposed projection”)
Open		Section lines
Solid thin with kinks		Long break lines
Dotted dotted with two points		Bend lines on reamers

Count	Font size	Type of letters	Note
		Lowercase	For the name of the documents font 5
		Uppercase
		Lowercase and uppercase
		Uppercase
5 and 6		Uppercase
7 and 8	3,5	Uppercase
		Lowercase and uppercase	In the top line
3,5	Bottom line
Rest	3,5	Lowercase

Images on drawings

Properly executed drawing has clarity and carries a large amount of information that is clear to the expert. Therefore, all drawings are carried out in accordance with established and applicable rules in all areas of activity. They are based on the combined achievements of science, technology and practical experience. The result of this work is standard.

In engineering graphics, standards are presented in the form of documents containing a number of requirements and standards established for universal and reusable use.

In our country, there are state standards (GOST) established for all products, as well as for norms, rules, requirements, concepts, designations, etc.

To perform this calculation and graphic work, it is necessary, in addition to knowing the standards for drawing design, to learn and apply the standards for the rules for the image of objects and drawing dimensions on drawings, rules for hatching and axonometric images.

The rules for depicting objects on drawings are set by GOST 2.305-68 "Images - views, sections, sections".

Images of objects are performed by the method of rectangular (orthogonal) projection. In this case, the object is located between the observer and the corresponding projection plane. For the main planes of projections take six faces of the cube, combined with the plane in accordance with Figure 6.

Figure 6 - The location of the main species in the drawing

The number of images should be the smallest, but providing a complete picture of the subject when applying the conventions, signs and inscriptions established in the relevant standards.

To reduce the number of images, it is allowed to show the necessary invisible parts of the surface of an object using dashed lines in accordance with Figure 7.

Figure 7 - The image of the object showing the invisible parts

Kinds

By sight  - called the image facing the observer visible part of the surface of the object.

The following are installed the main  species obtained on the main projection planes:

1. Image on the frontal plane of the projections - front view (main view);

2. Image on the horizontal plane of the projections - top view;

3. The image on the profile plane of the projections - left view;

4. Right view;

5. Bottom view;

6. Rear view.

The image of the object on the frontal plane of the projections is called the main view.  This image should give the most complete picture of the shape and size of the subject.

The names of views in the drawings are not inscribed, if they are made in a projection connection

If the projection connection is broken or the view is not located at the appropriate place, then the direction of projection should be indicated by an arrow in the corresponding view. Above the image and the arrow should be applied the same uppercase letter of the Russian alphabet in accordance with Figure 8.

Figure 8 - Types and simple cuts, and their designations in the drawing

If any part of the object cannot be shown on the main planes of the projections without distorting the form, apply additional viewswhich receive on the planes which are not parallel to the main planes of projections (fig. 9). Additional views are denoted similarly to the views on the main projection planes (Fig. 9). The additional view, located in direct projection connection with the corresponding image, is not indicated, and the direction of projection is not indicated. Allowed to turn an additional view to the position adopted for the subject in the main image. At the same time, the type designation must be supplemented with a conventional graphic symbol ã - with the “rotated” sign (Fig. 9). If necessary, indicate the value of the angle of rotation.

Figure 9 - Designation of an additional type

Local viewcalled the image of a separate, limited space surface of the object.

The local view may be limited by the line of a cliff or not, if it is necessary to read the shape of the protruding part of the object (Fig. 8, 9). Local view should be marked on the drawing like an additional view.

Cuts

To identify the internal structure of the object in the drawings, cuts and sections are made.

Cutcalled the image of the object, mentally cut one or more planes. In this case, mental dissection refers only to this section and does not entail changes in other images of the same object. The section shows what is produced in the section plane and what is located behind it (Fig. 8). It is allowed to show not everything that is located behind the secant plane, if this is not required for understanding the design of the object.

Depending on the number of cutting planes, the cuts are divided into simple -with one cutting plane (fig. 8) and complex -with several cutting planes (fig. 10, 11).

Depending on the position of the cutting planes, simple cuts are divided into horizontalif the cut plane is parallel to the horizontal plane of the projections, vertical(fig. 8), sloping, if the cutting plane is not parallel to any of the main planes of the projections. Vertical section called frontalif the cutting plane is parallel to the frontal plane of the projections and profileif the cutting plane is parallel to the frontal plane of the projections.

Complicated cuts include steppedwhen the cutting planes are parallel to each other (Fig. 10), and brokenif the cutting planes intersect at an angle of more than 90 ° (Fig. 11).

Figure 10 - Step cut

The position of the cutting section plane is indicated on the drawing by means of an open section line according to GOST 2.303-68. The initial and final stroke of the section line are drawn outside the contour of the image. In the case of a stepped section, the strokes are also drawn at the transition points of the cutting planes to another level, on broken sections - at the intersection of the cutting planes. At the initial and final stroke, perpendicular to them, at a distance of 2 ... 3 mm from the outer end of the stroke, the arrows indicate the direction of gaze. Outside of the arrows put the same uppercase letters of the Russian alphabet. At the same time over the corresponding image of the incision is an inscription of the type "AA".

When the cutting plane coincides with the plane of symmetry of the object as a whole, and the corresponding images are located on the same sheet in direct projection connection and are not separated by any other images, the position of the cutting plane is not marked for horizontal, frontal and profile sections, and do not accompany (fig. 8)

Horizontal, frontal and profile sections, as a rule, are located on the site of the corresponding main species.

A vertical section, when the cutting plane is not parallel to the frontal or profile planes of projections, as well as an inclined section, should be constructed and positioned in accordance with the direction indicated by the arrows on the section line. It is allowed to place such cuts in any place of the drawing, as well as with rotation to the position corresponding to that adopted for the given object on the main image. In the latter case, the legend must be added to the inscription ã - the “rotated” sign.

In the image of a broken section, the cutting planes are conventionally rotated to fit into one plane, while the direction of rotation may not coincide with the direction of gaze. If the combined planes are parallel to one of the main planes of the projections, then a broken section can be combined in the place of the corresponding type (Fig. 11). When the cutting plane is rotated, the elements of the object located behind it are drawn as they are projected onto the corresponding plane with which the combination is made.

Figure 11 - Broken cut

The section, which serves to clarify the device of the object in a separate, limited place, is called to local. Local incision is allocated in the form of a solid wavy line (Fig. 8, 12) or thin with kinks, according to GOST 2.303-68. These lines should not coincide with any other lines of the image.

For symmetrical images, you can connect half of the view and half of the section; moreover, if the axis of symmetry is vertical, then, as a rule, the view is placed to the left, and the section to the right (Fig. 12). If the axis of symmetry is horizontal, then the top is a view, the bottom is a slit. The line separating them is the axis of symmetry - a thin dash-dotted line.

Figure 12 - Connection of the part of the species and part of the section

If there is no symmetry or if the axis of symmetry of the part coincides with any contour line, for example, with an edge, part of the line and part of the section should be separated by a wavy line or a line with kinks drawn from one side or the other of the symmetry axis (Fig. 13). At the same time the line with a break should go beyond the contour of the image.

Figure 13 - Combination of part of the view and part of the section

Sections

By section  called the image of the figure, resulting in the mental dissection of the object in one or more planes. The section shows only what is obtained directly in the section plane.

It is allowed to use a cylindrical surface as a secant, which is then developed into a plane. The designation of the image is accompanied by a conventional graphic sign ä - “expanded”.

Sections not included in the section are divided into handed down(fig. 14 b, c) and superimposed(Fig. 14 a).

Figure 14 - Section: a - superimposed; b, c - rendered.

Outstanding sections can be located anywhere in the working area of ​​the drawing, as well as in the gap between the parts of the same type. The axis of symmetry of a pronounced or superimposed section is indicated by a dash-dotted line with no designation; letters and arrows are not drawn and the section line is not drawn (Fig. 14).

For asymmetrical sections, located in the gap or superimposed (Fig. 15), the section line is drawn and arrows are drawn, but the letters are not set. In all other cases, the designation of the section line and the section itself is carried out as well as for the section. The secant planes are chosen so as to obtain normal cross sections.

Figure 15 - Asymmetrical section: a - made; b - in the gap; in - imposed.

The section on the construction and location should correspond to the direction indicated by the arrows. Allowed to place the cross section in any field of the drawing, as well as with rotation with the addition of a sign (for example, AA).

If the cutting plane passes through the axis of the surface of revolution bounding the hole or recess, the contour of the hole or recess in the cross section is shown in full (Fig. 14).

The contour of the removed section, as well as the section included in the section, is encircled with solid main lines, and the contour of the superimposed section - with continuous thin lines.

If the section is obtained consisting of separate independent parts, the section should be drawn.

On images of sections and sections in places of dissection by the plane of the material of the part, depending on the type of material, shading is performed in accordance with GOST 2.306-68. If the part is made of metal, the hatching is applied with solid thin parallel lines at an angle of 45 ° to the lines of the drawing frame in the same direction on all sections of the same part. If the contour lines of the part or axial lines are at an angle of 45 ° to the lines of the drawing frame, then the angle of inclination of the hatching lines should be taken 30 ° or 60 °. The distance between the lines of the hatching should be the same for all sections of the part and can be selected from 1 to 3 mm depending on the area of ​​the hatching.

If the cutting plane passes along a thin wall or a stiffener of a part, then such a wall or edge does not conditionally hatch (Fig. 8).

The height of the letters in the designations of types, cuts and sections should be one or two sizes larger than the height of dimensional numbers adopted in this drawing. The minimum diameter of the signs "turned" and "expanded" is 5 mm.

Dimensioning

All images are accompanied by the application of sizes. When applying dimensions should be guided by the basic provisions of GOST 2.307-68 "Drawing dimensions and maximum deviations."

In the drawing the dimensions of the true value of the part and its elements are put down, regardless of the scale of the image.

Linear dimensions are indicated on the drawing in millimeters with no indication of the unit of measurement, angular dimensions are in degrees, minutes.

Dimensions in the drawings indicate the size numbers, extension and dimension lines (solid thin).

When drawing the size of a rectilinear segment, the dimension line is drawn parallel to this segment, the extension lines are perpendicular to the dimension line (Fig. 16).

Figure 16 - Drawing rectilinear and angular sizes

When drawing the size of an angle, the dimension line is drawn as an arc with a center at its top, and the extension lines are radially (Fig. 21).

Dimension lines are preferably applied outside the contour of the image. It is not allowed to use contour lines, axial, center and extension lines as dimension lines. It is necessary to avoid crossing the dimension and extension lines.

The dimension line at both ends is limited by the arrows resting on the extension lines (Fig. 17). The values ​​of the elements of the arrows of the dimension lines are selected depending on the thickness of the lines of the visible contour and draw them approximately the same throughout the drawing. The shape of the arrow and the approximate ratio of its elements are shown in Figure 17.

Figure 17 - Shapes and sizes of arrow elements

Extension lines are drawn from the lines of the visible contour. Extension lines should extend beyond the ends of the dimension line arrows by 1 ... 5 mm (Fig. 16).

The distance between the contour line and the dimension line is selected depending on the image size and saturation of the drawing. The minimum distance between the dimension line and the contour line should be 10 mm, and the minimum distance between parallel dimension lines should be 7 mm (Fig. 16).

Dimension numbers are applied over the dimension line as close as possible to its middle. When drawing several parallel dimension lines, dimension numbers should be arranged in a checkerboard pattern (Fig. 16).

Linear dimensions at different inclined dimension lines and angular dimensions, at different positions of the angles, are plotted as shown in Figure 21. If the dimension number of the linear or angular dimension applied above the middle of the dimension line falls within the shaded areas (within an angle of 30 °), then it is carried out on the horizontally positioned leader line. For corners of small sizes with insufficient space, dimensional numbers are placed on the shelves of the callout lines in any zone.

If there is not enough space for the application of arrows and dimension numbers, they are applied using one of the methods shown in fig. 18. If there is a lack of space for the arrows on the dimension lines arranged in a chain, the arrows can be replaced with serifs plotted at an angle of 45 ° to the dimension lines or clearly marked points (Fig. 18). If there is not enough space for an arrow due to a closely located contour or extension line, the latter can be interrupted.

Figure 18 - Drawing dimension lines with insufficient space for arrows

Dimension numbers are not allowed to be divided or intersected by any lines of the drawing. In the place where the dimension number is applied, the axial, center lines and hatching lines interrupt (Fig. 19). Contour lines are not allowed to interrupt.

Figure 19 - Drawing dimension lines and numbers when drawing contour lines and hatching lines.

It is recommended to group the dimensions related to the same structural element (groove, protrusion, hole, etc.) in one place, placing them on the same image in which the geometric shape of this element is shown most fully (Fig. 20) .

Figure 20 - Dimensioning the hole in the cut

A capital letter is placed in front of the radius dimension number. R, (eg, R20), before the size number of the diameter - the sign ñ (for example, ñ 20 ).

With a large radius, the center of the arc of a circle is allowed to approach the arc. In this case, the dimensional line of the radius is shown with a break at an angle of 90Å. If you do not need to specify dimensions that determine the position of the center of a circular arc, then the dimension line of the radius is allowed not to bring to the center and to shift relative to the center. When conducting several radii from one center, the dimension lines of any two radii do not fit on one straight line.

In the case of an image with a sphere, if it is difficult to distinguish it from other surfaces, it is allowed when applying the diameter (radius) size, the sphere is allowed to put the word "Sphere" or sign ?? (eg, Sphere R15,ñ 40 ).

The square in the drawing is determined by two sizes of its sides or one size with the sign ò (Fig. 21). Diagonals drawn by thin lines, conventionally denote a plane.

The dimensions of the chamfers at an angle of 45Å are plotted as shown in Fig. 21. The dimensions of the chamfers at different angles are indicated by linear and angular dimensions or by two linear dimensions.

Figure 21 - Dimensioning of detail elements.

In the case of execution in the drawing of an image in which the view is combined with a cut (top view or left), as well as when drawing a symmetrical figure to the axis of symmetry or with a break, the dimension line is drawn with a break, which is made further than the axis or break line of the image (Fig. . 22).

Figure 22 - Drawing dimension lines with a break

The total number of sizes should be minimal, but sufficient to manufacture and control the product. The dimensions of the same element in the drawing are not allowed to be repeated. The dimensions of several identical elements of the product, as a rule, are applied once with the number of these elements on the shelf or below it (Fig. 23). Moreover, for elements evenly spaced around the circumference (for example, holes), the angular dimensions between them are not set, provided that one of these elements lies on one of the axes of symmetry (Fig. 23 a). Only the size of the diameter of the circle on which the centers of the holes are located (ñ 32   on fig.23 a). If none of the holes lies on the axis of symmetry, then you should set the angle to the first element (Fig. 23 b).

Figure 23 - Dimensioning the size and location of the holes on the circle: a - on the axes of symmetry; b - outside the axis of symmetry

The sequence of execution:

analyze the shape of the part, determine the types of surfaces bounding it, select the number of images and the main image;

determine the size of the images, select the size of a sheet of paper, draw the lines of the frame and the main inscription columns, draw the overall rectangles of the images;

fit the received image rectangles into thin lines;

apply remote and dimension lines with arrows;

measure the part and put dimensional numbers;

circle the sketch.

What product is called a part?

Detail  - product, from homogeneous in name and grade of material without the use of assembly operations.

What are the requirements for the sketch details?

Sketch - a working drawing of the part, made without the use of drawing tools (except pencil and compasses) by hand with exemplary respect for the proportions of the part. Sketching requirements are similar to those for working drawings.

What are the features of sketching parts of an assembly unit?

agree on the dimensions of the mating surfaces of the parts and dimension these dimensions from the design bases;

take into account the rules for making drawings of jointly processed parts;

take into account the rules for the implementation of assembly drawings for some products (reinforced, with welding or casting, etc.);

to make sketches (drawings of standard products and standard elements of parts in accordance with the requirements of the standards;

take into account the possibility of drawing up group design documents for several parts of the same type

What product is called an assembly unit?

Assembly unit  - the product, the components of which are to be connected to each other at the manufacturing plant by assembly operations (screwing, joint, riveting, welding, soldering, crimping, flared, gluing, stitching, stacking, etc.)

What are the similarities and differences in drawing and sketch details?

Similarities:

h and e. are technical documents; execution hours and e. must comply with the rules for the implementation of working drawings; and hours and e. must contain the optimal number of images; besides the image details h. and e. contain data on the deviation of its shape and size, material brand.

Differences:

h. performed drawing tools, and e. by hand; h. draw a scale, e. without it, respecting the proportions of the parts; h. perform on drawing paper, and e. on writing paper.

What design document is called a part drawing?

Drawing details  - a document containing images of parts and other data necessary for its manufacture and control.

What determines the choice of the size of the image drawing (sketch)details anddrawing sheet format?

The size of the image is selected depending on the complexity and size of the part. The format is selected in accordance with the size of the image.

How to divide the image on the drawing (sketch) depending on their content?

View, section, section.

What should be the total number of images on the drawing?

The number of images in the drawing should be the smallest, but providing a complete picture of the shape of the product when using standards established conventions, symbols, signs and labels.

What is the main image on the drawing?

The main image of the product is the image that gives the most complete picture of the device, shape and dimensions of the product.

What determines the choice of the main image and what are the requirements for it?

The main image of the product is chosen so that it gives the most complete picture of the device, shape and size of the product.

As shown in the longitudinal section of the screws, bolts, studs, rivet keys, axles, solid shafts?

Unshaded

What simplifications are used to reduce the number of images?

if the view, section or section is a symmetrical figure, it is allowed to draw only half of the image, limiting it with an axial line, or a little more than half. In the second case, the boundary line is the break line.

if a part has several identical, evenly spaced elements, then one or two such elements can be shown on the image of this part. For the rest indicate their location and a note on their number.

if one surface smoothly passes into another, then the transition line can be omitted or a conventional image drawn with a thin line.

a slight taper or slope is allowed to depict with increasing.

long objects with a constant or regularly changing cross-section can be depicted discontinuously.

for flat parts, only one view can be made, indicating the thickness of the part, denoted by the letter s.

to simplify the drawing and reduce the number of types, GOST 2.305-68 allows:

to depict a section of the subject;

perform complex cuts;

show in the section openings located on the round flange, regardless of whether they fall into the section plane or not

\u003e\u003e Drawing: Views. Number of views in the drawings

You already know that the images of the projection drawing are called projections. The images used in technical drawings are called views.

View- this picture  facing the observer visible part of the surface of the object. Standard sets  six main types, which are obtained by projecting an object placed inside the cube on all its faces (Fig. 130). The six faces of the hollow cube unfold to align with the frontal plane of the projections (Fig. 131).

The following species names are established:
1. Front view - main view (located on the front projection site).
2. The view from above (under the main view) is located on the spot. horizontal  projection.
3. View to the left (located to the right of the main view).
4. View to the right (located to the left of the main view).
5. Bottom view (located above the main view).
6. Rear view (located to the right of the left view).

The names of species on the drawings do not inscribe. The image taken on the back face of the cube, which corresponds to the frontal plane of the projections, is taken as the main view.

The subject is located relative to the frontal plane. projections  so that the image on it gives the most complete picture of the shape and size of the object.

The number of views in the drawing should be chosen minimal, but sufficient to understand the shape of the depicted object. In the views it is allowed to show the necessary invisible parts of the surface of an object with the help of dashed lines (Fig. 132).

In the drawing, the distance between species is chosen arbitrarily, but in such a way that dimensions can be applied. In the drawings it is not allowed to put the same twice. the size  , because it clutters the drawing, makes it difficult to read and use in work. Views, as well as projections, are located in a projection connection.

When constructing drawings, sometimes only a part of the view is performed. The image of a narrow surface area of ​​a part surface is called a local view. Local species are limited to the line of the cliff (Fig. 133). In fig. 133 local view is located in the projection connection. In this case, it is not indicated. In the front view, the arrow indicates the direction of the sight.

If a local view is not located in a projection connection, then in the view it is indicated by an arrow and a letter of the Russian alphabet, but picture  a local species is inscribed with the same letter (Fig. 134).

On the local species is allowed to put down the size.

Questions and tasks
1. Define the concept of "type".
2. How are the views of drawings ?
3. Name the images shown in fig. 135, 136.

4. What does the dashed line in the left view (Fig. 136) mean?
5. Why drawing is the main graphic document on production ?
6. On the visual image of the part (Fig. 137) find the corresponding main view and top view. Write the answer in the workbook.
7. In fig. 138 arrows A, B, C show the directions of projection. Select the projection direction that should correspond to the main view of the part.
8. Determine how many images are needed to identify the shape. parts  (fig. 139). Explain which signs you intend to use to reduce the number of species. Give the answer in writing.

N.A. Gordeenko, V.V.Stepakova - Drawing., 9 the class
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