Slide 2

Definition

A section is an image of a figure obtained by mentally dissecting an object with a plane. The section shows only what is located directly in the cutting plane.

Slide 3

Applying shading

The cross-sectional figure in the drawing is highlighted by hatching, which is applied with thin lines at an angle of 45°.

Hatching is applied to the cross-section image at an angle of 45 to the right

or to the left, at a distance of 2-3 mm (2-10 mm).

Bushing section Bushing

Bushing section Bushing– a cylindrical or conical part with an axial hole.

Rules for making a cut

1. We cut the part with a cutting plane.

2. We discard part of the part located between the cutting plane and the observer.

3. We replace the dashed lines with which the internal outlines were depicted in the main view with solid main lines, because they became visible.

4. Apply shading to the section included in the section. Hatching is given only where solid parts of the part fall into the cutting plane.

Designation of cuts in the drawing

1. The position of the cutting plane is shown in the drawing by an open line. Stroke length 8 – 20 mm, thickness s up to 1.5 s.

2. Directions of view are indicated by arrows drawn at a distance 2-3 mm from the edge of the stroke.

3. Near each arrow, on the outside, capital letters of the Russian alphabet are applied indicating the cut. The font size of the letters should be twice the size of the digits of the size numbers.

4. Above the section there is a corresponding inscription indicating the cutting plane. The inscription contains two letters separated by a dash.

Classification

cuts

Classification of cuts

1. Depending on the number of cutting planes, the sections are divided on the:

Simple - if one cutting plane is used for the cut.

Complex - if several cutting planes are used (stepped, broken).

2. Depending on the position of the cutting planes relative to the horizontal plane of projections, the sections are divided into:

Vertical - if the cutting plane is perpendicular to the horizontal plane of projections (frontal, profile)

Horizontal - if the cutting plane is parallel to the horizontal projection plane

Inclined - if the cutting plane has an inclination to the horizontal plane of projections other than straight

3. Full and local

Local - a cut that serves to clarify the internal structure of an object only in a separate, limited place

Classification of cuts

Horizontal section placed in projection connection, in place of the top view

Construction of sections

Sections. Execution rules. Definition. A section is an image of a figure obtained by mentally dissecting an object with a plane. The section shows only what is located directly in the cutting plane. Applying shading. The cross-sectional figure in the drawing is highlighted by hatching, which is applied with thin lines at an angle of 45°. Rules for making sections. Sections in the drawings are divided into extended and superimposed. Extended sections are preferable, because they do not clutter the view with unnecessary lines. The outline of the exposed sections is made with a solid line. Designation of sections. If the section is extended, then draw an open line, two thick strokes. - Section.ppt

Connecting a view and a section

Deleting a view line. The dashed lines that used to depict the internal outlines are now outlined by solid main lines, as they are rendered visible. Hatching a section figure. Incision. View. The boundary between half the view and half the section is the dash-dot center line. The boundary between part of the view and part of the section is a solid wavy line. Main view and top view. - View.ppt

Drawing. Cuts

Drawing. General lessons for all sections. All sections of drawing. Getting the cut. Comparison of cuts and sections. Frontal section. Horizontal section. Profile section. Algorithm for constructing a frontal section. According to the visual image and this species determine the appropriate cut and make it in the appropriate dimensional rectangle. - Sections.ppt

Image of points, lines and planes

Descriptive geometry. Image of points, lines and planes. Solving basic positional problems. Subject and method of descriptive geometry. Projection methods. Straight line. Plane. In descriptive geometry, a drawing is constructed using the projection method. When constructing drawings, the projection properties of figures are widely used. The rules for constructing images are based on the projection method. Subject and method of descriptive geometry. Orthogonal projection is a special case of parallel projection. Orthographic projection is most widely used in technical drawings. - Geometry.ppt

Fillet circles

Geometric constructions. Goal: to master the technique of constructing mates in drawings. Pairing is called smooth transition one line to another. What is pairing? What is needed to build a pairing? Types of pairing. Conjugation of two circles. Conjugation of a circle and a straight line. Constructing the conjugation of circles. Algorithm for constructing a pairing. Creative work. - Pairings.ppt

Degree of angles

Warm up. Extra figure. Crossword. Lesson topic. The unit of measurement for angle is degree. What is a degree and its designation in writing. The name of the device for measuring angles, its structure and use. In Ancient Babylon, people decided to divide the circle into 360 central angles because there are 360 ​​days in a year. Degree. 1?. Protractor. Practical work on the use of a protractor. Degree - 1?. Scale. Protractor center. -

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Slide captions:

Sections

Sections and sections Purpose of sections Rules for making sections Features of making sections Purpose of sections The difference between a section and a section Rules for making cuts Types of sections Connecting half a view and half a section Connecting part of a view and part of a section

Sections A section is an image of a figure obtained by mentally dissecting an object with a plane.

Sections A section shows only what is in the cutting plane. A section is not an action, but an image. The cross-sectional figure in the drawing is highlighted by hatching, which is applied with thin lines at an angle of 45 degrees.

Rules for making sections According to their location in the drawing, sections are divided into extended and superimposed asymmetrical symmetrical Extended sections are placed outside the contour of the image of the part at any place in the drawing field, superimposed - directly on the views. The contour of the extended section is outlined with a solid thick line, the contour of the superimposed section is outlined with a solid thin line, and the contour of the view at the location of the section is not interrupted.

Extended sections 1 2 3 Section made in projection connections Section made in an arbitrary place in the drawing Section made in an extension of the section plane

Features of making sections Sections are made on the same scale as the image to which it belongs, or indicate the scale if it is changed. In terms of construction and location, the section must correspond to the direction indicated by the arrows. If the cutting plane passes through the axis of the surface of revolution that bounds the hole, then their contour is shown in full on the section.

The difference between a section and a section A section differs from a section in that it shows not only what is in the cutting plane, but also what is behind it. A-A A-A Section Incision

Purpose of cuts A cut is an image of an object mentally dissected by a plane. In this case, the part of the object located between the observer and the cutting plane seems to be removed. The section shows what is in the cutting plane and behind it. Therefore, the cut includes a section.

Rules for making cuts The dashed lines that depict the internal outlines in the main view are now outlined with solid main lines, since they have become visible. The section figure included in the section is shaded. Hatching is given only where solid parts of the part fall into the cutting plane.

Types of cuts A simple cut is a cut formed by a single plane. The position of the cutting plane can be vertical, horizontal, or inclined. A compound cut is a cut formed by two or more planes.

Frontal sections When the cutting plane is parallel to the frontal plane of projections, the vertical section is called frontal. The frontal section is usually located in the projection connection - at the site of the main view. If the cutting plane coincides with the axis of symmetry of the part and the section is located in a projection relationship, it is not designated. FRONTAL SECTION

Profile sections When the cutting plane is parallel to the profile plane of projections, the vertical section is called profile. The profile section is usually placed in a projection connection - in place of the view on the left. PROFILE SECTION

Horizontal cuts HORIZONTAL SECTION If the cutting plane is horizontal, the cut is called horizontal. The horizontal section is usually placed in a projection connection - in the place of the top view.

Simple cuts When the cutting plane is located at a certain angle to the horizontal plane of projections, the cut is called an inclined one. To show the device of a part in a separate, limited place, a local section is used. It is highlighted in the view by a solid thin wavy line.

Connection of half of the view and half of the section. Dimension lines related to a part element drawn only up to the axis of symmetry are drawn slightly further than the axis and limited by an arrow on one side. The size indicated is full. When connecting half of the view and half of the section, you must remember: The border between the view and the section should be the axis of symmetry, a thin dash-dotted line

Connection of half of the view and half of the section. The section in the drawing is placed to the right of the axis of symmetry or below it. On half of the view, dashed lines depicting the contour of the internal outlines are not drawn

Connecting part of a view and part of a section. Part of a view and part of a section are separated by a solid wavy line. If the contour line coinciding with the axis of symmetry refers to the outer surface of the part, most of the view is shown. If the contour line coinciding with the axis of symmetry refers to the hole, most of the section is shown in the drawing.

Complex cuts If the cutting planes are parallel, then the cut is called a stepped cut. If the cutting planes are located at an angle not equal to 90 degrees, then the cut is called a broken one.

By performing various exercises, we became convinced that the completeness of representation of the shape of the depicted object depends on the choice of the number of types.

However, in practice you can encounter objects whose shape is difficult to determine from a drawing using only views.

Obviously, we need some more images, the use of which will allow us to better understand the shape of the object and reduce the time it takes to complete and read the drawing.

The shape of the part shown in the figure is generally cylindrical, stepped. Can we judge the shape of each element of the part from this drawing? Obviously not.

All this can be clarified using sections.

Section - this is an image of a figure obtained by mentally dissecting an object with a plane.

The section shows only what is located directly in the cutting plane (with the exception of cylindrical holes).

Please note that the section is not an action, but an image!

In the visual image we see how the shape of the part is revealed using cutting planes A and B. The figures located in the planes are shown under the view.

The cross-sectional figure in the drawing is highlighted by hatching, which is applied with thin lines at an angle of 45º. The distances between the lines are chosen depending on the hatching field. But they must be the same for all sections of one part.

The cutting plane is designated as follows:

- draw an open line, two thick strokes 8 - 20 mm long, this open line should not cross the main contour;

- arrows indicate the direction of view; they are placed at the outer ends of the open line at a distance of 2 - 3 mm from the end of the stroke;

- On the outside of the arrows, identical capital letters of the Russian alphabet are applied in font size No. 5, i.e. height 5 mm;

- The same letters are written above the section, separated by a dash, for example, A – A.

Depending on their location in the drawing, sections are divided into extended and superimposed.

Extended sections are placed outside the contour of the part image in any free space in the drawing field or in a break in the part image.

Overlaid sections are placed directly on the views. They are mainly used in drawings of rolled products of various profiles, tools, etc.

When making drawings of parts, offset sections are often used. The standard gives preference to them, since they do not load the view with unnecessary lines.

The contour of the extended section is outlined with a solid thick main line of the same thickness ( s ), as well as a line, which is also used to depict the visible contour of an object.

The contour of the superimposed section is outlined with a solid thin line (from s/3 to s /2), and the outline of the view at the location of the superimposed section is not interrupted.

Designation of sections.

To show where the cutting plane passes, it is designated.

If the section is taken out, then, as a rule, an open line is drawn with arrows indicating the direction of view and with the letters of the Russian alphabet.

The extended section can be placed on an extension of the section line. If the section figure is symmetrical relative to this line, then the section is not indicated by arrows and letters. The section line in this case is the center line.

The extended section can also be placed in the gap between parts of the same type.

The conditional break of an object in the drawing is shown as thin (from s /2 to s /3) wavy line.

As in the previous example, there are no open lines indicating the position of the cutting planes or labels. This designation is possible in the case when the sectional figure is symmetrical with respect to the cutting plane.

If the sectional figure located in the gap is not symmetrical, then draw an open line with arrows, but do not indicate it with letters.

Superimposed sections are usually not marked. Only in the case when it is an asymmetrical figure, open line strokes and arrows are drawn, but letters are not applied.

Basically, sections are made to the same scale as the image to which it relates, or indicate the scale if it is changed.

In terms of construction and location, the section must correspond to the direction indicated by the arrows.

EXCEPTION:

If the cutting plane passes through the axis of a hole or recess limited by a surface of revolution (cylindrical, conical or spherical), then the entire contour of the hole or recess is shown. You cannot divide a section figure into parts.

In practice, it is necessary to perform sections of objects made from various materials. For each of them, the standard provides a certain type of graphic symbols.

Most often you will come across a graphical representation of metal in cross-section. It is done with inclined parallel hatching lines.

Hatch lines can be drawn on the drawing with an inclination to the left or to the right, but in the same direction on sections for the same part.