- (effective cross-section), a quantity characterizing the probability of the transition of a system of two colliding hs as a result of their scattering (elastic or inelastic) to a certain final state. C. s is equal to the ratio of the number dN of such transitions in units ... ... Physical Encyclopedia

SECTION, sections, cf. (book). 1. only units Action according to ch. Sech 1 in 1, 2 and 3 digits Caesarean section (see Caesarean; honey). Golden ratio (see golden). 2. The place where something is cut, crossed, cut. Live section (see live). ... ... Explanatory Dictionary of Ushakov

Separation, cut; carving, profile, scraping, hysterotomy, beating Dictionary of Russian synonyms. section noun spanking Dictionary of Russian synonyms. Context 5.0 Informatics. 2012 ... Synonym dictionary

SECTION, I, cf. 1. see section 2. 2. Location, according to rum. cut, cut. Cross with. Conical c. II. SECTION. See Sec. 1. Ozhegov's Explanatory Dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Explanatory Dictionary Ozhegova

SECTION 1, I, cf. Explanatory Dictionary Ozhegova. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Explanatory Dictionary Ozhegova

See section 1. Ozhegov's Explanatory Dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Explanatory Dictionary Ozhegova

section  - Image obtained by the mental dissection of an object by one or several planes [Terminological dictionary of construction in 12 languages \u200b\u200b(VNIIIS Gosstroy of the USSR)] Design topics, documentation EN cross sectioneutsection DE ... ... Technical Translator Reference

Section  - an image in the form of a flat figure resulting from the mental dismemberment of an object by a plane (several planes) ... Publishing Dictionary

Section  - - image of a figure resulting from the mental dissection of an object by one or more planes. The section shows only what is obtained directly in the secant plane. [GOST 2.305 68] Rubric of the term: General terms ... ... Encyclopedia of terms, definitions and explanations of building materials

SECTION  - see Parafilariasis ... Horse breeding guide

SECTION  - in drawing, an image of a figure resulting from the mental dissection of an object (part) of one million by several planes to identify the shape of individual elements (grooves, edges, protrusions, holes, etc.), as well as identify the shape of profiles (see). ... ... Big Polytechnical Encyclopedia

Books

• The Golden Ratio, I. Sh. Shevelev, M.A. Marutaev, I.P. Shmelev, 1990 Edition. Good safety. It is well known: the golden ratio is the law of the proportional connection of the whole and the parts that make up the whole. This book tells about the golden phenomenon ... Category: Painting. Theory and Technology Publisher: Stroyizdat,
• Golden ratio. Literary and artistic almanac, Collection, Here is the first issue of the literary and artistic almanac Golden Section. This project was created specifically for those who want to publish their works and find a way to their ... Category: Poetry Publisher: Golden SectionManufacturer:

Section  - an image obtained by mentally dissecting a part with one or more planes. The section is part of the section or is considered as an independent image in the drawing.

By the method of constructing sections, those not included in the section are divided into external and superimposed. Preference should be given to those that can be placed on the free field of the drawing in the projection connection, or outside the projection connection, or in the gap image. Examples of superimposed symmetric section and rotated asymmetric section are shown in Figure 1.

Figure 1 Example of a superimposed symmetric section without a designation

The superimposed section is drawn in thin lines. If the secant plane passes through an opening having the shape of a surface of revolution, then the cross section is performed by a closed contour according to the type of cut. The shape of the section is divided into symmetric and asymmetric. Figure 2 shows an example of a symmetrical AA and asymmetric BB sections of a part.

Figure 2 staked symmetrical and asymmetric sections

An example of an asymmetric section in the image break is shown in Figure 3.

Figure 3 Section in the gap image, asymmetric

Designation and hatching of sections is carried out in accordance with the requirements of GOST 2.305-2008.

Last update date 04/05/2018

Literature:

1. V.N. Bykova G.D. Methodiev L.Ya. Methodius V.I. Sedinin Engineering and Computer Graphics: Textbook - Novosibirsk: SibGUTI, 2010
2. ESKD in student work: textbook. manual / V. Ya. Vayspapir, G.P. Katunin, G.D. Mefodeva - Novosibirsk: SibGUTI, 2009 .-- 215 p.

Section- an image of a figure obtained by mentally dissecting an object with one or more planes.
The section shows only what is obtained directly in the secant plane.

Cross sections are usually used to identify the transverse shape of an object. The cross-sectional figure in the drawing is distinguished by hatching. Dashed lines are applied in accordance with general rules.

Section formation procedure:
1.   A secant plane is introduced in the place of the part where it is necessary to more fully identify its shape. 2.   The part of the part located between the observer and the secant plane is mentally discarded. 3.   The sectional shape is mentally rotated to a position parallel to the main plane of projections P. 4.   The image of the section is formed in accordance with the general rules of projection.

Sections that are not part of the structure are divided into:

Taken out;
- superimposed.

Spaced sections  are preferred and may be placed in a gap between parts of the same species.
The contour of the extended section, as well as the section included in the section, is depicted by solid main lines.

Superimposedare called section, which is placed directly on the subject. The contour of the superimposed section is performed by a solid thin line. The cross-sectional shape is placed in that place of the main view, where the secant plane passes, and shaded.

Overlay sections: a) symmetrical; b) asymmetric

Axis of symmetry  the superimposed or staked section is indicated by a dash-dotted thin line without letters and arrows and the section line is not drawn.

Cross sections at break.  Such sections are located in the gap of the main image and perform a solid main line.
For asymmetric sections located in a gap or superimposed, a section line is drawn with arrows, but is not indicated with letters.

Cross section at break: a) symmetrical; b) asymmetric

Spaced sections  have:
- anywhere in the drawing field;
- in place of the main species;
- with rotation with the addition of the sign "rotated"

If the secant plane passes through the axis of the surface of rotation that bound the hole or recesses, then their contour in the section is shown completely, i.e. perform according to the cut rule.

If the section is obtained consisting of two or more separate parts, then a section should be applied, up to a change in the direction of view.
The secant planes are chosen so as to obtain normal cross sections.
For several identical sections related to the same subject, the section line is denoted by one letter and one section is drawn.

Remote elements.
Detail element - a separate enlarged image of a part of an object to represent details not indicated on the corresponding image; may differ from the main image in content. For example, the main image is a view, and the detail is a section.

In the main image, part of the subject is distinguished by a circle of arbitrary diameter, made by a thin line, from it there is a leader line with a shelf over which an uppercase letter of the Russian alphabet is placed, higher than the height of the dimensional numbers. The same letter is written above the extension element and to the right of it in parentheses, without the letter M, indicate the scale of the extension element.

Production drawings contain various types of images - views, sections, sections.

Sections and sections allow you to identify the external and internal (Fig. 147, a, b) shape of the part. The named images are obtained as a result of mental dissection of the part by a secant plane, the position of which is selected depending on the shape of the imaged part. Sections and sections complement and clarify geometric information about the subject and thereby increase the ability to identify the shape of the depicted object in the drawing. In some cases, they have a greater information capacity than species. Sections and sections are projection images and are performed according to the rules of rectangular projection.

Fig. 147. Section (a) and section (b)

Section   - the image of the figure resulting from the mental dissection of an object by a secant plane. The section shows only what is in the secant plane.

The detail is projected onto the projection plane V (Fig. 148, a). Then it is mentally dissected by a secant plane in the place where it is necessary to clarify the shape of the product. In a secant plane, a sectional shape is obtained. After that, the secant plane (together with the sectional shape) is mentally taken out, rotated around the vertical axis, moved parallel to the projection plane and aligned with the V plane so that the front view images and the sectional figures do not obscure each other (Fig. 148, b). Please note that with this movement of the secant plane, the front view is in projection connection with the cross section. The resulting image of the sectional shape is called a section made in projection communication.

The secant plane with the sectional figure can be moved in an arbitrary direction, combining it with the projection plane, without taking into account the projection connection. Such a section is called a section made on an empty spot in the drawing (Fig. 148, c). The section can also be located on the continuation of the trace of the secant plane (Fig. 148, d). It is called a section made on the continuation of the trace of the secant plane.

If the section is located on the continuation of the trace of the secant plane, then the section is not indicated (see Fig. 148, d). If the cross section is located on a free spot in the drawing, then it is indicated with an inscription of the type “A - A” (see Fig. 148, b, c).

If the secant plane passes along the axis of the cylindrical or phonic surface that bound the hole or recess, then their contour in the section is shown completely, for example, the image of the conical-shaped recess (see Fig. 148).

To identify the shape of some parts, sometimes it is necessary to perform several sections, which in the drawing are denoted by the letters of the Russian alphabet (Fig. 149).

GOST 2.305-68 establishes the rules for the image and designation of sections.

The contours of the sectional shape of the part are depicted by a solid main line. Inside these contours give a conditional graphic designation of the material of the part (table. 12).

Fig. 148. Sections:

a - obtaining a section; b - section built in projection connection with the view; in - section made in the free space of the drawing; g - section made on the continuation of the trace of the secant plane

Fig. 149. Designation of sections by letters of the Russian alphabet

12. Graphic designations of some materials in the drawings

The position of the secant plane is indicated on the drawing by a section line.

The axis of symmetry of the superimposed or extended section is indicated by a dot-and-dot thin line without letters and arrows and the section line is not drawn (Fig. 5.3, but, b; 5.4, b) In all other cases, an open line is used for the section line (see Fig. 5.2, c; 5.4, a, b).

Fig. 5.4.

An open line is drawn in the form of individual strokes that do not intersect the contour of the corresponding image. The thickness of the strokes of the open line is taken in the range from s to 1½ s  and their length is from 8 to 20 mm. At the initial and final strokes, perpendicular to them, at a distance of 2-3 mm from the end of the stroke, put arrows indicating the direction of view. The shape, size ratio of these arrows and the relative position of the arrows and open line are shown in Fig. 5.5.

Fig. 5.5.

At the beginning and end of the section line put the same capital letter of the Russian alphabet. In this case, the initial letters of the alphabet ( BUT, B, C, D, D  etc.). Letters are applied near the arrows indicating the direction of view (see Fig. 5.4, a, b) with  the outside. An inscription is made over the section according to type A - A, i.e. two identical letters, through a dash.

If the section is in a gap between parts of the same type, then with a symmetrical figure, the section line is not drawn (see. Fig. 5.3, g).

For asymmetric sections located in the gap (Fig. 5.4, d) or superimposed (Fig. 5.4, e), the section line is drawn with arrows, but the letters do not indicate.

The section can be rotated. Then a conditional graphic designation should be added to the inscription, placed on the line, with the section designation (see Fig. 5.4, at).

Some rules for constructing sections. In the drawing of one part there can be as many different sections as needed to fully identify its shape.

For several identical sections related to the same object, the section lines should be denoted by the same letter and one section drawn (Fig. 5.6).

Fig. 5.6.

The secant planes should be chosen so that normal cross sections are obtained (see Fig. 5.4, c) In this case, the cross section may turn out to consist of two parts with a gap (see Fig. 5.4, g).

Sometimes, when performing a section, the secant plane passes through the axis of the surface of revolution, which limits the hole or recess, for example, through a cone-shaped recess or cylindrical through holes (Fig. 5.7). In this case, in the cross-sectional figure, the contour of the hole or recess is shown completely. However, it should be noted that this applies to images of holes and recesses of a cylindrical, conical and spherical shape and does not apply to the image in the section of the keyway.

Fig. 5.7.

If the secant plane passes through a non-circular hole and the section is made up of separate independent parts, then cuts should be used.

The cross section is usually performed on the same scale as the view to which it refers. Then the holes, recesses and other elements that are on the cross-sectional figure will be the same dimensions as in the types of the drawing (see. Fig. 5.2 and 5.3).

The section should, by construction and location, correspond to the direction indicated by the arrows. It is recommended to choose the projection direction for asymmetric sections based on the following. If the section line is vertical, the section is usually aligned with the drawing plane by rotation from left to right (see Fig. 5.2, at; 5.3, at;  5.6; 5.7); if the section line runs horizontally, then rotate "toward you" (see Fig. 5.4, but).

Failure to comply with these conditions leads to the errors shown in Fig. 5.8. An error in the section under which the inscription is made Wrong,  consists in the following: the scale is not maintained; the groove in the section is shown on the left, which does not correspond to the selected projection direction (it should be located on the right, since it is located on the part in front); there is no inscription above the section A - A.

Fig. 5.8.

The necessary dimensions are applied to the sections, for example, the width and depth of the keyway, the diameter and depth of the recesses, etc.

Reading sectional drawings

Consider the sectional drawing shown in Fig. 5.9.

Fig. 5.9.

The drawing is one view of the part. However, despite the presence of only one type, the shape of the part and its individual elements can be easily installed. Considering the main view of the part from left to right, it can be established that the first, second, and third steps have a cylindrical shape, and the last is in the shape of a regular quadrangular prism. Four sections help to establish this, the data in the drawing.

Cross section inscription A – A  shows that it refers to the first cylindrical element of the part, which has a rectangular groove and a conical recess. The width and depth of the grooves and recesses are visible in the section. The groove is cut only on the side of the part visible in the drawing. This we determine by its absence on the left side of the circle depicting the section.

Section B - B  contains a rectangular cutout on the left side that shows the shape, width and depth of the keyway. The groove is shown on the left side, since it is located on the back of the part, which can be judged by the fact that it is shown by the dashed line in the main view.

The part of the part having the largest diameter contains three cylindrical holes located at an angle of 120 °. The depth, diameter and direction of the axes of the holes are determined by the cross section B - B.  It is important to note that the contour of the section at the intersection with these holes is not interrupted, since they have a cylindrical shape. In the center of the section AT – AT  Shows a cylindrical hole running along the axis of the part.

The cross-section of a square shape does not have an inscription. A thin dash-dot line without arrows and letters was drawn at the site of the section line. The absence of arrows, letters and inscriptions above the square section is explained by the fact that the section is symmetrical and its axis of symmetry coincides with the section line.

In the center of this section, an open circle is shown showing a cylindrical hole along the axis of the part. The section is hatched at an angle of 30 °, not 45, otherwise the hatching lines would coincide with the section contour, which is not recommended.