# Lines, Images of objects, Graphic designations of materials and rules for their application on drawings - Machine parts. Course design

## Lines

GOST 2.303-68 establishes the outline and the main purpose of the lines in the drawings.

A solid thick line is taken as the main line of the drawing, the thickness of which should be in the range from 0.6 to 1.4 mm. The thickness of the lines should be the same for all images in this drawing, drawn on the same scale.

Thin lines on drawings of all formats made in pencil are carried out with a thickness of 0.55 •; formats from A5 to A2, made with ink - a thickness of 0.335; formats А1 and more, executed by ink, - thickness 0,55.

## Images of objects

Images of objects (types, sections and sections) should be performed in accordance with GOST 2.305-68.

Images of objects should be performed by the method of rectangular projection into two, three or more planes of projections. In this case, the object is supposed to be located between the observer and the corresponding projection plane (Figure 2.11).

Six faces of the cube are taken for the main projection planes (1, 2, 3, 4, 5, 6 - figure 2.11).

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The edges are aligned with the plane (Figure 2.12). The face indicated by the number 6 can also be located next to the face 4.

The image on the frontal plane is taken as the main one.

Images in the drawing, depending on their content, are divided into views, sections, sections.

View - the image of the visible part of the surface of the object facing the observer. Species are divided into main, additional and local.

Fig. 2.11

Fig. 2.12

The main views are a front view (main view), a top view, a left view, a right view, a bottom view, a rear view. To designate the main views in the drawing, only if there is no projection relationship between them and the main view.

An additional view is a view obtained on a non-parallel of none of the main projection planes. It is used in the case when any part of the object can not be shown on the main types without distortion of shape and size. An additional view should be placed in the direction of the projection indicated by the arrow (Figure 2.13). An additional view can be mixed or rotated with a mandatory designation in accordance with Table. 2.6.

A local view is an image of an individual, limited place on the surface of an object.

The local view can be either limited by a break line (if possible in the smallest size), or is not limited.

For the depiction of curved and curved objects apply deployed species, which are designated in accordance with Table. 2.6 and Fig. 2.14. In this case, curved and curved objects must be deployed in one plane without distorting the image. In the image of bent objects, the contours are made with a solid main line, and the bend point is indicated by a thin dash-dot line with two dots (Figure 2.14).

On the basic view, the product must be positioned so that the image gives the most complete picture of its shape and size.

The location of the species should be performed in accordance with Fig. 2.12. Species located differently (including those located on another sheet), and the direction of projection should be marked as shown in Fig. 2.15 and in Table. 2.6.

The view designations must be executed in a position parallel to the title block of the drawing above the corresponding image.

The structure of the designation of species is shown in Table. 2.6.

An incision is an image of an object that is mentally dissected by one or more planes, while the mental dissection of an object is only relevant to this section and does not involve the modification of other images of the same object.

Fig. 2.13

Fig. 2.14

Fig. 2.15

Table 2.6

Specification of species (GOST 2.305-68)

The section shows what is obtained in the cutting plane and what is behind it.

It is recommended that you use

for types, cuts and sections:

a) uppercase letters of the Latin and Russian alphabets;

b) Arabic numerals;

c) a combination of numbers and letters, for example, A2.

Do not use letters:

• from the Latin alphabet /, О, Ч, (), Х

• from the Russian alphabet 3, Q, 0, X, Ф, Ч, Ь, б.

Letters, numbers, or combinations thereof must be used alphabetically or in numerical order, without repetitions and without omissions, regardless of the number of sheets in the drawing.

All parts of an object intersected by a plane are shaded, emptiness does not hatch. In addition, it should be remembered that elements such as screws, rivets, keys, hollow shafts and spindles, handles, etc., in the longitudinal section are not shown dissected.

Normally, not cut in the longitudinal section, they represent nuts and washers. Balls always show not dissected.

The stiff walls like stiffeners, spokes of flywheels, pulleys, gears are shown unshaded if the secant plane passes along the axis or the long side of such an element.

The methods for marking sections and sections in the drawings are given in Table. 2.7. The plane of the cut must pass so that it is possible to show the characteristic shapes of the product. The positions of the plane of the cut or section are denoted by an open line in the form of strokes of length (10-12) mm.

Table 2.7

Designations of sections and section (GOST 2.305-68)

For a complex cut (broken or stepped), the strokes are also carried out at the kinks of the section line (Figure 2.16).

The strokes must not intersect the outline of the image. At the initial and final strokes, to indicate the direction of projection, put the arrows at a distance (2-3) mm from the end of the stroke.

The plane of the cut is indicated by the same letter or letter in combination with a digit (see the use of letters and numbers above). Letters (or letters with numbers) are placed directly near the arrows indicating the direction of projection.

Fig. 2.16

It is possible not to represent the imaginary plane of the cut and not to represent the image of a simple cut in the following cases:

a) the position of the plane of the cut is unambiguous;

b) the image of the cut is obtained by the principle of rectangular projection onto the main planes;

c) the image of the cut is in direct connection with the image from which the cut is made (Figure 2.17).

For identical images of sections (sections) in several secant planes, it is allowed to draw

Fig. 2.17

only one of these sections (sections), denoting the plane of the cut with the same letter (Figure 2.18).

Inclined slits, as a rule, are placed in the direction of projection (Figure 2.17), however, it is allowed to depict them with rotation (Figure 2.19).

Fig. 2.18

In both cases, the designation of the cut must match Table. 2.7.

When a broken section is drawn, the elements, cut by imaginary planes, are displayed before aligning in one plane (Figure 2.20).

The elements visible behind the plane of the cut are represented as they are projected onto the corresponding plane to which the alignment is made (Figure 2.20).

The elements of the stepped sections, cut by the plane of the cut, are shown in the same plane without unfolding the plane of the cut, and only the parts visible in the projection direction are displayed (Figure 2.16).

A partial cut is selected in the form of a wavy line (Figure 2.21) or a line with a kink, and this line must not coincide with any other lines of the image.

Symmetrical objects can be represented by connecting half the view and half the cut. Border

Fig. 2.19

Fig. 2.20

between them - the axis of symmetry. In the section, the lower or the right half of the object is shown without a section designation. The incisions of curved objects can be unfolded in a plane to obtain an undistorted image with a designation in accordance with Table. 2.7.

Section - an image of a figure resulting from a mental dissection of an object by one or more planes. The section shows only what is obtained directly in the cutting plane. Cross-sections are an integral part of the section. In case they are portrayed on their own, they are divided into those taken out and superimposed.

The cross sections are placed outside the image of the object, the superimposed sections are combined with the corresponding kind of object. The contours of the sections that make up the section and the outlined sections are shown as solid thick ones (bases -

Fig. 2.21

lines); the contours of the superimposed sections are represented by continuous thin lines, without interrupting the contour of the image of the object at the place of the superimposed section, the surface of the section is stroked, the superimposed section and the imaginary secant plane are not designated (Figure 2.22).

The superimposed and (or) remote sections are displayed so that the direction of projection onto the plane of the section coincides with the direction of the view of the object to the right or from below.

The resulting sections, if uniquely determined, can be plotted on an axis that coincides with the position of the imaginary secant plane. Their contours are represented by a continuous main line. In this case, the cross-section and the cutting plane are not indicated. If the position of the cutting plane is not uniquely determined, the cross section must be indicated in accordance with Table. 2.7. The imaginary plane of the section must pass so that an undistorted image of the section is obtained (Figure 2.22).

When displaying a series of transverse sections or sections, they can be placed:

a) using the method of rectangular projection onto the main planes (Figure 2.12) or hook, as shown in Fig. 2.18; imaginary secant planes and individual images must be indicated;

b) as the outlined sections; individual images can be labeled (see Figure 2.23);

c) at any place in the drawing with the designation of cutting planes and image sections.

Remote element - an additional separate image (usually enlarged) of any part of the subject, requiring graphic and other explanations regarding the shape, dimensions and other data. The remote element should be placed as close as possible to the corresponding place in the image of the object. When the remote element is executed, the corresponding place is marked on the view, section or section by a closed continuous thin line-a circle, an oval, etc., with the designation of the remote element on the shelf of the leader line, in capital letters of the Latin or Russian alphabet, or a combination of them with Arabic numerals. The remote element should be indicated similarly with the scale (see Figure 2.24). This element may contain details not specified in the corresponding image, differ from it in content, for example, the image is a view, and the remote element is a cut. When placing the details of the element separately from the main image, the latter is given a link where the element is shown (Figure 2.24).

The number of images in the drawings should be minimal, necessary for a complete and unambiguous representation of the subject (the product and its constituent parts).

The details should be displayed in a functional position or in a position convenient for their manufacture.

Assembly units should be displayed in a functional position. However, with an inclined functional position, they are displayed vertically or horizontally.

Fig. 2.22

Fig. 2.23

Fig. 2.24

The invisible contours and facets of objects are depicted only in cases where it is necessary to explain the design of the product or to reduce the number of images.

For symmetric figures, it is allowed to draw half the image, noting the symmetry axis at each end with two parallel segments of at least 3.5 mm in length (Figure 2.25).

Evenly repeating identical elements of one object can be represented once in the beginning or at the end of an object, and the rest of them can be represented by simplified continuous lines (Figure 2.26) or conditionally according to existing standards (Figure 2.27). In this case, the dividing (step) circles or straight lines on which the repetitive elements are arranged are made with dot-dash lines; to represent one element, and for others - to designate only their axes (Figure 2.27).

Clear edges of visible intersections and transitions are performed by the main line and brought to the contour line.

Smooth crossings and transitions, as a rule, do not represent. If necessary, they can be denoted by a continuous thin line, which is not brought to the contour line (Figure 2.23).

A slight slope or taper is allowed to be represented

Fig. 2.25

Fig. 2.26

Fig. 2.27

with increasing (Figure 2.17). If the incline or taper is not clearly detected, only one line is used, corresponding to a smaller size of the element with a slope or smaller base of the cone (Figure 2.17).

Long objects with a constant or regularly changing cross-section (for example, a shaft) may be drawn with a break (Figure 2.28).

Fig. 2.28

The object image can be ripped open:

• Two continuous parallel lines with kinks;

• Two solid thin lines drawn by hand.

The plane surfaces of the object are distinguished by continuous thin lines drawn diagonally (Figure 2.28).

Items from transparent materials are depicted as opaque.

A part of an object or its elements (for example, a scale, an arrow, etc.) behind transparent elements can be represented as visible.

Items consisting of identical elements (a package of adjusting shims of the bearing assembly, etc.), can be depicted as a monolithic body.

For objects with a continuous mesh, braid, knurled, etc., these elements should be represented by continuous thin lines, and it is allowed to apply them in part (Figure 2.21).

The extreme positions of the moving parts are represented in the form of a contour by a thin dash-dot line with two dots. In this case, the contour lines and faces of the object, located behind the moving parts, are represented as visible.

Neighboring objects, given only for explanation, are drawn in the form of a contour with a thin dashed-dot line with two dots. These objects can be drawn with a thin solid line.

The contour lines and faces of the depicted object, hidden by neighboring objects given for explanation, are depicted as visible.

## Graphical designations of materials and rules for their application in drawings

Graphical designations of materials in cross-sections, depending on the type of materials, are performed in accordance with GOST 2.306-68. For four groups of materials, the graphic designations are given in Table. 2.8.

Table 2.8

Graphical designations of materials in section (GOST 2.306-68)

Hatching in sections is performed in the form of straight parallel lines drawn at an angle of 45 ° or to the line of the contour of the image, or to its axis, or to the line of the frame of the drawing.

If the hatching lines drawn to the lines of the drawing frame at an angle of 45 ° coincide with the contour lines or with the center lines instead of the 45 ° angle, an angle of 30 ° or 60 ° should be adopted. The hatching angle can be either right or left, but for all cuts and sections of the same part it should be performed in the same direction.

The distance between the hatch lines must be the same for all cross sections of a given part performed on the same scale. The distance between the hatch lines is 1-10 mm (depending on the size of the drawing).

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