How to build a third view of two data. Building a third view from two known views

A complete technical drawing contains at least three projections. However, the knowledge to imagine an object in two projections is required from both the technologist and the skilled worker. It is consequently in exam papers in technical universities and colleges, there are continuous tasks on the construction of the third type according to two given ones. In order to successfully complete a similar task, you need to know the conventions adopted in technical drawing.

You will need

- paper;
- 2 projections of the part;
- drawing tools.

Instruction

1. The theses for constructing the third view are identical for classical drawing, sketching and drawing in one of the pre-prepared for this computer programs. Before each, analyze the given projections. See what kind you are given. When we are talking about 3 views, it is general projection, top view and left view. Determine what is given to you. This can be done according to the location of the drawings. The left view is located on the right side of the general, and the top view is below it.

2. Establish a projection link with one of specified types. This can be done by extending the horizontal lines that limit the silhouette of the object to the right, when you want to build a view from the left. If we are talking about a top view, continue down the vertical lines. In any case, one of the part parameters in your drawing will appear mechanically.

3. Find the 2nd parameter on the existing projections, which limits the silhouettes of the part. When constructing a view on the left, you will find this size in the top view. When establishing a projection relationship with the main view, the height of the part appeared in your drawing. So, from the top view, you need to take the width. When constructing a top view, the 2nd dimension is taken from the side projection. Mark the silhouettes of your object in the third projection.

4. See if the part has protrusions, voids, holes. This is all noticed on the general projection, which, by definition, should give the most accurate idea of the subject. True, just as when determining the general silhouette of a part in the third projection, establish a projection connection between different elements. The remaining parameters (say, the distance from the center of the hole to the edge of the part, the depth of the protrusion, etc.) are found in the side or top view. Build the necessary elements, considering the measurements you have found.

5. In order to check how well you coped with the task, try to draw a detail in one of the axonometric projections. See how reasonably the elements of the third type you have drawn are located on the volumetric projection. It may well be that you will have to make some adjustments to the drawing. A drawing with perspective can also help to check your construction.

One of the most interesting tasks descriptive geometry - the construction of the third kind for given 2. It requires a thoughtful approach and a meticulous measurement of distances, therefore it is not invariably given the first time. However, if you carefully follow the recommended sequence of actions, erecting the 3rd type is absolutely acceptable, even without spatial imagination.

You will need

- paper;
- pencil;
- ruler or compasses.

Instruction

1. First of all, try on the two available kind m to determine the shape of the individual parts of the depicted object. If the top view shows a triangle, then it may be triangular prism, cone of revolution, triangular or quadrangular pyramid. The shape of a quadrangle can be taken by a cylinder, a quadrangular or triangular prism, or other objects. An image in the form of a circle can represent a sphere, a cone, a cylinder, or other surfaces of revolution. One way or the other, try to imagine the general form of the object in the aggregate.

2. Draw the boundaries of the planes, for the comfort of transferring lines. Start the transfer from the most comfortable and intelligible element. Take any dot that you correctly "see" on both kind x and move it to the 3rd view. To do this, lower the perpendicular to the boundaries of the planes and continue it on a further plane. Please note that when switching from kind on the left in the top view (or opposite), you need to use a compass or measure the distance with a ruler. So in place of your third kind two lines intersect. This will be the projection of the selected point on the 3rd view. In the same way, it is allowed to transfer as many points as desired, until the general view of the part becomes clear to you.

3. Check if the build is correct. To do this, measure the dimensions of those parts of the part that are reflected entirely (say, a standing cylinder will be the same "height" in the left and front views). In order to realize that you have not forgotten anything, try to look at the front view from the position of the observer from above and count (though approximately) how much the boundaries of holes and surfaces should be visible. The whole line, every point must be reflected on all kind X. If the part is symmetrical, do not forget to mark the axis of symmetry and check the equality of both parts.

4. Delete everything auxiliary lines, check that all visible lines are marked with a dotted line.

In order to depict this or that object, its individual elements are first depicted in the form of simple figures, and then their projection is performed. Projection construction is often used in descriptive geometry.

You will need

- pencil;
- compass;
- ruler;
- reference book "Descriptive Geometry";
- elastic.

Instruction

1. Carefully read the data of the task: for example, the general projection F2 is given. The point F belonging to it is located on the lateral surface of the cylinder of revolution. It is required to build 3 projections of point F. Mentally imagine how it all should look, then proceed to build an image on paper.

2. A cylinder of rotation can be represented as a rotating rectangle, one of the sides of which is taken as the axis of rotation. The second side of the rectangle - opposite to the axis of rotation - forms side surface cylinder. The remaining two sides represent the bottom and top base of the cylinder.

3. Due to the fact that the surface of the cylinder of revolution when constructing the given projections is made in the form of a horizontally projecting surface, the projection of the point F1 must certainly coincide with the point P.

4. Draw the projection of the point F2: from the fact that F is on common surface rotation cylinder, the point F2 will be the point F1 projected onto the lower base.

5. Build the third projection of the point F using the y-axis: put F3 on it (this projection point will be located to the right of the z3 axis).

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Note!
When constructing image projections, follow the basic rules used in descriptive geometry. Otherwise, the projection will fail.

Helpful advice
In order to build isometric image, use the top base of the rotation cylinder. To do this, first build an ellipse (it will be placed in the x'O'y' plane). After that, draw tangent lines and the lower half-ellipse. After that, draw a coordinate polyline and, with its support, construct the projection of the point F, that is, the point F’.

There are not so many people in our time who have never in their lives been able to draw or draw something on paper. Knowing how to execute a primitive drawing of some kind of construction is occasionally quite useful. It is allowed to spend a lot of time explaining “on the fingers” how this or that thing is made, while one glance at its drawing is enough to realize it without every word.

You will need

- sheet of drawing paper;
– drawing accessories;
- drawing board.

Instruction

1. Select the sheet format on which the drawing will be made - in accordance with GOST 9327-60. The format should be such that it is allowed to place the main kinds details in the appropriate scale, as well as all the necessary cuts and sections. For simple parts, choose A4 (210x297 mm) or A3 (297x420 mm) format. The 1st can be located with its long side only vertically, the 2nd - vertically and horizontally.

2. Draw a drawing frame, stepping back from the left edge of the sheet 20 mm, from the rest 3 - 5 mm. Draw the main inscription - a table in which all data about details and drawing. Its dimensions are determined by GOST 2.108-68. The width of the core inscription is constant - 185 mm, the height varies from 15 to 55 mm, depending on the purpose of the drawing and the type of institution for which it is performed.

3. Select the main image scale. Permissible scales are determined by GOST 2.302-68. They should be preferred such that all the main elements are perfectly visible on the drawing. details. If at the same time some places are not clearly visible, they can be moved separate view, showing with the desired magnification.

4. Select main image details. It should be such a direction of looking at the part (projection direction), from which its design is revealed most fully. In most cases, the main image is the location in which the part is on the machine during the core operation. Parts that have an axis of rotation are located on the main image, as usual, so that the axis has a horizontal arrangement. The main image is located in the upper part of the drawing on the left (if there are three projections) or close to the center (if there is no side projection).

5. Determine the location of the remaining images (side view, top view, sections, cuts). Kinds details are formed by its projection onto three or two mutually perpendicular planes(Monge method). In this case, the part must be located in such a way that the set or all of its elements are projected without distortion. If any of these views is informational redundant, don't do it. The drawing should have only those images that are needed.

6. Select cuts and sections to be executed. Their difference from each other lies in the fact that the section shows what is behind the cutting plane, while the section displays only what is located in the plane itself. The cutting plane can be stepped or broken.

7. Proceed at ease to drawing. When drawing lines, follow GOST 2.303-68, which defines kinds lines and their parameters. Place the images at such a distance from each other that there is enough space for sizing. If the cut planes pass through the monolith details, hatch the sections with lines going at an angle of 45°. If at the same time the hatching lines coincide with the main lines of the image, it is allowed to draw them at an angle of 30 ° or 60 °.

8. Draw dimension lines and mark dimensions. In doing so, follow the following rules. The distance from the first dimension line to the silhouette of the image must be at least 10 mm, the distance between adjacent dimension lines must be at least 7 mm. Arrows are required to have a length of about 5 mm. Write numbers in accordance with GOST 2.304-68, take their height equal to 3.5-5 mm. Place the numbers closer to the middle of the dimension line (but not on the image axis) with some offset relative to the numbers on adjacent dimension lines.

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Performing an accurate drawing repeatedly requires large expenditures of time. Consequently, in case of an urgent need to make some part, it is often not a drawing that is made, but a sketch. It is performed quite quickly and without the use of drawing tools. At the same time, there is whole line requirements that the sketch must meet.

You will need

- detail;
- paper;
- pencil;
- measuring instruments.

Instruction

1. The sketch must be accurate. According to him, the person who will make a copy of the part should form an idea of \u200b\u200bhow appearance products, and about it design features. Therefore, before each observantly inspect the object. Determine the relationship between the various parameters. See if there are holes, where they are, their size and the ratio of diameter to the overall size of the product.

2. Decide which view will be the main view and how accurate it represents the detail. The number of projections depends on this. There may be 2, 3 or more. How many projections you need depends on their location on the sheet. You need to proceed from how difficult the product will be.

3. Choose a scale. It should be such that the master can easily make out even the smallest details.

4. Start sketching with center and center lines. In the drawings, they are usually indicated by a dotted line with dots between the strokes. These lines indicate the middle of the part, the center of the hole, etc. They remain on the working drawings.

5. Draw the outer silhouettes of the part. They are marked with a thick permanent line. Take care to correctly convey the ratio of sizes. Draw inner (noticeable) outlines.

6. Complete the cuts. This is done exactly the same as in any other drawing. The solid surface is shaded with oblique lines, the voids remain unfilled.

7. Draw dimension lines. From the points, the distance between which you want to designate, parallel vertical or horizontal strokes depart. Between them, draw a straight line with arrows at the ends.

8. Measure detail. Specify the length, width, hole diameters and other dimensions needed for precise work. Write the dimensions on the sketch. If necessary, apply signs indicating the methods and qualities of processing different surfaces of the product.

9. The final stage of work is filling the stamp. Enter your product information into it. In technical universities and design organizations, there are standards for filling stamps. If you are making a sketch for yourself, then it is allowed to indicate primitively what kind of part it is, the material from which it is made. The one who will make the part should see all other data in your sketch.

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The drawing serves to ensure that the one who will grind a part or build a house can get the most accurate idea of the appearance of the object, its structure, the ratio of parts, surface treatment methods. One projection for this, as usual, is unsatisfactory. On the training drawings usually perform three types - the main, left and top. For objects of difficult shape, right and rear views are also used.

You will need

- detail;
— measuring instruments;
- drawing tools;
- computer with AutoCAD.

Instruction

1. The sequence of drawing on a sheet of Whatman paper and in AutoCAD is approximately identical. Look at the details first. Determine which view of it will give the most accurate idea of the shape and functional features. This projection will become its main view.

2. See if your part looks identical when viewed from the right and left. Not only the number of projections depends on this, but also their location on the sheet. The left view is located to the right of the main one, and the right view is, respectively, to the left. At the same time, in a flat projection, they will look as if they are at ease in front of the observer's eyes, that is, without perspective control.

3. Drawing construction methods are identical for all projections. Mentally position the object in the system of planes on which you will project it. Analyze the shape of the object. See if it is permissible to divide it into more primitive parts. Answer the question, in the form of which body it is allowed to completely inscribe your object in its entirety or any of its fragments. Imagine how the individual parts look in orthogonal projection. The plane on which the object is projected when constructing the view on the left is located on the right side of the object itself.

4. Measure the item. Remove the main parameters, set the ratio between the whole object and its individual parts. Select the scale and draw the main view.

5. Select a build method. There are two of them. To complete the drawing using the removal technique, first apply the general silhouettes of the object, on the one that you are looking to the left or right. After that, gradually begin to remove volumes, drawing recesses, silhouettes of holes, etc. When receiving an increment, one element is first drawn, and then the rest are slowly added to it. The choice of method depends primarily on the difficulty of the projection. If the detail, when looking at it from the left or right, is a clearly expressed geometric figure a small number of deviations from the severe form, it is more comfortable to apply the removal technique. If there are a lot of fragments, and the part itself cannot be entered into any figure, it is better to stepwise attach the elements to each other. The difficulty of the projections of the same part can be different, and therefore the methods can be changed.

6. In any case, start building the side view with the bottom and top lines. They must be on the same tier as the corresponding lines of the main view. This will provide a projection connection. Later, apply the general silhouettes of the part or its first fragment. Observe the ratio of sizes.

7. After drawing the overall silhouettes of the side view, apply centerlines, hatches, etc. Dimension it. It is not always necessary to sign a projection. If all views of the part are located on one sheet, then only the rear view is signed. The location of the remaining projections is determined by the standards. If the drawing is made on several sheets and one or both side views are not on the sheet on which the main one is, they need to be signed.

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Helpful advice
When constructing a side view in AutoCAD or another drawing program, it is not strictly necessary to combine the top and bottom lines of the main and side views at the first stage. It is allowed to execute the drawing in fragments, and combine the tiers when you start preparing it for printing.

Construction of the third type on two known types.

Let the main view and the top view be known. It is necessary to build a view on the left.

Two main methods are used to build a third type according to two known ones.

Building a third view using an auxiliary line.

In order to transfer the size of the width of the part from the top view to the left view, it is convenient to use the auxiliary straight line (Fig. 27a, b). It is more convenient to draw this straight line to the right of the top view at an angle of 45° to the horizontal direction.

To build a third projection A 3 peaks BUT let's go through it front projection A 2 horizontal line 1 . It will contain the desired projection A 3. After that, through a horizontal projection A 1 draw a horizontal line 2 until it intersects with the auxiliary line at the point A 0. Through the dot A 0 draw a vertical line 3 to the intersection with the line 1 in desired point A 3.

The profile projections of the other vertices of the object are constructed similarly.

After an auxiliary straight line is drawn at an angle of 45 °, it is also convenient to construct a third projection using a T-square and a triangle (Fig. 27b). First through frontal projection A 2 draw a horizontal line. Draw a horizontal line through the projection A 1 there is no need, it is enough, by applying a T-square, to make a horizontal notch at the point A 0 on the auxiliary line. After that, having slightly moved the T-square down, we apply the square with one leg to the T-square so that the second leg passes through the point A 0, and note the position profile projection A 3.

Building a third view using baselines.

To construct the third view, it is necessary to determine which lines of the drawing should be taken as the base lines for measuring the dimensions of the object images. As such lines, they usually take axial lines (projections of the planes of symmetry of the object) and projections of the planes of the bases of the object. Let's take an example (Fig. 28) of building a view on the left according to two given projections of an object.

Rice. 27 Building a third projection from two data

Rice. 28. The second way to build a third projection from two data

Comparing both images, we establish that the surface of the object includes surfaces: regular hexagonal 1 and quadrangular 2 prisms, two cylinders 3 and 4 and truncated cone 5 . The object has a frontal plane of symmetry F, which is convenient to take as a base for measuring the width of individual parts of an object when constructing its view on the left. The heights of individual sections of the object are measured from the lower base of the object and are controlled by horizontal communication lines.

The shape of many objects is complicated by various cuts, cutouts, and intersections of the constituent surfaces. Then you first need to determine the shape of the intersection lines, build them on individual points, introducing the notation of the projections of the points, which, after completing the constructions, can be removed from the drawing.

On fig. 29, a left view of an object is constructed, the surface of which is formed by the surface of a vertical cylinder of rotation with T-shaped notch in its upper part and a cylindrical hole occupying a front-projecting position. The plane of the lower base and the frontal plane of symmetry were taken as base planes F. Image T-shaped notch in the left view built using points A, B, C, D and E the contour of the cut, and the line of intersection of cylindrical surfaces - using points K, L, M and they are symmetrical. When constructing the third type, the symmetry of the object relative to the plane is taken into account F.

Rice. 29. Building a view on the left

5.2.3. Construction of transition lines. Many details contain lines of intersection of various geometric surfaces. These lines are called transition lines. On fig. 30 shows a bearing cover, the surface of which is limited by surfaces of rotation: conical and cylindrical.

The intersection line is built using auxiliary cutting planes (see Section 4).

The characteristic points of the intersection line are determined.

Construction of the third projection of the part according to two data

First you need to find out the shape of the individual parts of the object; To do this, you need to simultaneously consider both given images. It is useful to keep in mind which surfaces correspond to the most common images: a circle, a triangle, a hexagon, etc. In the form of a triangle in the top view (Fig. 41), the following can be depicted: triangular prism 1, triangular 2 and quadrangular 3 pyramids, cone of revolution 4, truncated prism 5.

The shape of a quadrilateral (square) can be seen from above (Fig. 41): cylinder 6, triangular prism 8, quadrangular prisms 7 and 10, as well as other objects limited by planes or cylindrical surfaces 9.

The shape of a circle can be seen from above: a sphere, a cone, a cylinder and other surfaces of revolution. The top view in the shape of a regular hexagon has a regular hexagonal prism.

Having determined the shape of individual parts of the surface of an object, one must mentally imagine their image in the left view and the entire object as a whole.

Various methods are used to construct a third view according to two data: construction using general dimensions; using an auxiliary line; using a compass; using straight lines drawn at an angle of 45 °, etc.

Let's consider some of them.

Construction using an auxiliary line(Fig. 42). In order to transfer the size of the part width from the top view to the left view, it is convenient to use the auxiliary straight line. It is more convenient to draw this straight line to the right of the top view at an angle of 45° to the horizontal direction.

To build a third projection BUT 3 peaks BUT, draw through its frontal projection BUT 2 horizontal line 1. The desired projection will be on it BUT 3 . After that, through a horizontal projection BUT 1 draw a horizontal line 2 until it intersects with the auxiliary line at the point BUT 0 . Through the dot BUT 0 draw a vertical line 3 until it intersects with line 1 at the desired point BUT 3 .

The profile projections of the other vertices of the object are constructed similarly.

After an auxiliary straight line has been drawn at an angle of 45 O, it is also convenient to construct a third projection using a T-square and a triangle (Fig. 80b). First through frontal projection BUT 2 draw a horizontal line. Draw a horizontal line through the projection BUT 1 there is no need, it is enough, by applying a T-square, to make a horizontal notch at the point BUT 0 on the auxiliary line. After that, having slightly moved the T-square down, we apply the square with one leg to the T-square so that the second leg passes through the point BUT 0 , and mark the position of the profile projection BUT 3 .

Building with baselines. To construct the third view, it is necessary to determine which lines of the drawing should be taken as the base lines for measuring the dimensions of the object images. As such lines, they usually take axial lines (projections of the planes of symmetry of the object) and projections of the planes of the bases of the object.

Let's take an example (Fig. 43) of building a view on the left according to two given projections of an object.

Comparing both images, we establish that the surface of the object includes surfaces: regular hexagonal 1 and quadrangular 2 prisms, two cylinders 3 and 4 and a truncated cone 5. The object has a frontal plane of symmetry F, which is convenient to take as a base for measuring the width of individual parts of an object when constructing its view on the left. The heights of individual sections of the object are measured from the lower base of the object and are controlled by horizontal communication lines.

On fig. 44, a left view of an object is constructed, the surface of which is formed by the surface of a vertical cylinder of rotation with T-shaped notch in its upper part and a cylindrical hole occupying a front-projecting position. The plane of the lower base and the frontal plane of symmetry Ф were taken as base planes. Image T-shaped notch in the left view built using points BUT,AT,With,D and E the contour of the cut, and the line of intersection of cylindrical surfaces - using points To,L,M and they are symmetrical. When constructing the third type, the symmetry of the object relative to the plane is taken into account F.

2.6. test questions

1. What image is taken in the drawing as the main one?

2. How is the object positioned relative to the frontal projection plane?

3. How are the images in the drawing divided depending on their content?

4. What are the rationales for choosing the number of images?

5. What image is called a view?

6. How are the main views in the projection relationship in the drawing and what are their names?

7. What types are designated and how are they inscribed?

8. What is the size of the letter used to designate the species?

9. What are the ratios of the sizes of the arrows indicating the direction of view?

10. What species are called additional, which are local?

11. When is an additional species not designated?

12. What image is called a cut?

13. How do you indicate the position of the cutting plane during cuts?

14. What inscription marks the incision?

15. What is the size of the letters at the section line and in the inscription marking the section?

16. How are cuts divided depending on the position of the cutting plane?

17. When is a vertical section called frontal, when - profile?

18. Where can horizontal, frontal and profile sections be located and when are they not indicated?

19. How are cuts classified depending on the number of cutting planes?

20. How is a section line drawn in a complex section?

21. What cuts are called stepped? How are they drawn and labeled?

22. What cuts are called broken lines? How are they drawn and labeled?

23. What cut is called local and how does it stand out in the view?

24. What serves as a dividing line when connecting half of the view and section?

25. What serves as a dividing line if, when connecting half of the view and section, the contour line coincides with the axis of symmetry?

26. How is a stiffener shown in a section if the cutting plane is directed along its long side?

27. How is the contour of a group hole revealed in a circular flange if it does not fall into the plane of this cut?

28. What image is called a section?

29. How are sections that are not included in the section classified?

30. What sections are preferred?

31. Which line depicts the outline of the extended section and which line - the outline of the superimposed section?

32. What sections do not designate and do not inscribe?

33. How do you indicate the position of the cutting plane during a section?

34. What inscription accompany the section?

35. How is the extended section placed on the drawing field?

36. What is accepted symbol to display a section along the axis of a surface of revolution bounding a hole or recess?

38. How are different sections hatched in a detail drawing?

39. List the ways to build a third type of detail from two data.

The main element in the solution graphics tasks in engineering graphics is a drawing. A drawing is a graphic representation of objects or their parts. The drawings are made in strict accordance with the rules of projection in compliance with the established requirements and conventions. Moreover, the rules for depicting objects or their constituent elements in the drawings remain the same in all industries and construction.

The image of the object in the drawing should be such that it can be used to establish its shape as a whole, the shape of its individual surfaces, combination and mutual arrangement its individual surfaces. In other words, the image of the object should give full view about its shape, device, dimensions, as well as the material from which the object is made, and in some cases include information about the methods of making the object. A characteristic of the size of the object in the drawing and its parts are their dimensions, which are applied to the drawing. The image of objects in the drawings is performed, as a rule, "on a given scale.

Images of objects in the drawing should be placed so that its field is evenly filled. The number of images in the drawing should be sufficient to obtain a complete and unambiguous idea of it. At the same time, the drawing should only have required amount images, it should be minimal, i.e. the drawing should be concise and contain a minimum amount graphic images and text sufficient for free reading of the drawing, as well as its production and control.

The visible contours of objects and their faces in the drawings are made with a solid thick main line. The necessary invisible parts of the object are performed using dashed lines. In the event that the depicted object has constant or regularly changing cross sections, is performed in the required scale and does not fit on the drawing field of the specified format, it can be shown with breaks.

The rules for constructing images on drawings and drawing up drawings are given and regulated by a set of standards " unified system design documentation" (ESKD).

Image on drawings can be done different ways. For example, using rectangular (orthogonal) projection, axonometric projections, linear perspective. When performing engineering drawings in engineering graphics, the drawings are performed using the rectangular projection method. Rules for the image of objects, in this case products, structures or corresponding constituent elements in the drawings are established by GOST 2.305-68.

When constructing images of objects by the method of rectangular projection, the object is placed between the observer and the corresponding projection plane. For the main projection planes, six faces of the cube are taken, inside which the depicted object is located (Fig. 1.1.1, a). Faces 1,2 and 3 correspond to the frontal, horizontal and profile projection planes. The faces of the cube with the images obtained on them are combined with the plane of the drawing (Fig. 1.1.1, b). In this case, face 6 can be placed next to face 4.

The image on the frontal projection plane (on face 1) is considered the main one. The object is positioned relative to the frontal plane of projections so that the image gives the most complete picture of the shape and size of the object, carries most information about him. This image is called the main image. Depending on their content, images of objects are divided into types, sections, sections.

The image of the visible part of the surface of the object facing the observer is called the view.

GOST 2.305-68 establishes the following name for the main views obtained on the main projection planes (see Fig. 1.1.1): 7 - front view (main view); 2 - top view; 3 - left side view; 4 - right side view; 5 - bottom view; b - rear view. In practice, three views are more widely used: front view, top view and left view.

The main views are usually located in a projection relationship with each other. In this case, the name of the views on the drawing does not need to be inscribed.

If any view is displaced relative to the main image, its projection connection with the main view is broken, then an “A” type inscription is made above this view (Fig. 1.2.1).

The direction of view should be indicated by an arrow marked with the same capital letter of the Russian alphabet as in the inscription above the view. The ratio of the sizes of the arrows indicating the direction of view should correspond to those shown in fig. 1.2.2.

If the views are in a projection relationship with each other, but are separated by any images or are located on more than one sheet, then an inscription of the “A” type is also made above them. Additional view is obtained by projecting an object or part of it onto an additional projection plane that is not parallel to the main planes (Fig. 1.2.3). Such an image must be performed in the case when any part of the object is not depicted without distorting the shape or size on the main projection planes.

An additional projection plane in this case can be located perpendicular to one of the main projection planes.

When an additional view is located in direct projection connection with the corresponding main view, it is not necessary to designate it (Fig. 1.2.3, a). In other cases, an additional view should be marked on the drawing with an inscription of type "A" (Fig. 1.2.3, b),

and for the image associated with the additional view, you need to put an arrow indicating the direction of the view, with the corresponding letter designation.

Auxiliary View can be rotated while maintaining the same position as this subject on the main image. In this case, a sign must be added to the inscription (Fig. 1.2.3, c).

A local view is an image of a separate, limited place on the surface of an object (Fig. 1.2.4).

If the local view is located in direct projection connection with the corresponding images, then it is not indicated. In other cases, local views are designated similarly to additional types; a local view can be limited by a cliff line (“B” in Fig. 1.2.4).

First of all, you need to find out the shape of the individual parts of the surface of the depicted object. To do this, both given images must be viewed simultaneously. It is useful to keep in mind which surfaces correspond to the most common images: triangle, quadrilateral, circle, hexagon, etc.

On the top view in the form of a triangle, they can be depicted (Fig. 1.3.1, a): triangular prism 1, triangular 2 and quadrangular 3 pyramids, cone of revolution 4.

An image in the form of a quadrangle (square) can be seen from above (Fig. 1.3.1, b): a cylinder of rotation 6, a triangular prism 8, quadrangular prisms 7 and 10, as well as other objects limited by planes or cylindrical surfaces 9.

The shape of a circle can be seen from above (Fig. 1.3.1, c): ball 11, cone 12 and cylinder 13 of rotation, other surfaces of rotation 14.

The top view in the form of a regular hexagon has a regular hexagonal prism (Fig. 1.3.1, d), which limits the surfaces of nuts, bolts and other parts.

Having determined the shape of individual parts of the surface of an object, one must mentally imagine their image in the left view and the entire object as a whole.

To construct the third view, it is necessary to determine which lines of the drawing should be taken as the base for reporting the dimensions of the object image. As such lines, axial lines are usually used (projections of the planes of symmetry of the object and projections of the planes of the bases of the object). Let's analyze the construction of the view on the left using an example (Fig. 1.3.2): according to the main view and the top view, construct a left view of the depicted object.

Comparing both images, we establish that the surface of the object includes surfaces: regular hexagonal 1 and quadrangular 2 prisms, two cylinders 3 and 4 of rotation and a truncated cone 5 of rotation. The object has a frontal plane of symmetry Ф, which is convenient to take as the basis for reporting the dimensions of the width of individual parts of the object when constructing its view on the left. The heights of individual sections of the object are measured from the lower base of the object and are controlled by horizontal communication lines.

The shape of many objects is complicated by various cuts, cuts, and intersections of the surface components. Then you first need to determine the shape of the intersection lines, and you need to build them by individual points, introducing the designations of the projections of the points, which, after completing the constructions, can be removed from the drawing.

On fig. 1.3.3, a left-hand view of an object is constructed, the surface of which is formed by the surface of a vertical cylinder of revolution, with a T-shaped notch in its upper part and a cylindrical hole with a frontally projecting surface. The plane of the lower base and the frontal plane of symmetry F were taken as base planes. M and im symmetrical. When constructing the third type, the symmetry of the object with respect to the F plane was taken into account.

The image of an object mentally dissected by one or more planes is called a cut. Mental dissection of an object refers only to this section and does not entail changes in other images of the same object. The section shows what is obtained in the cutting plane and what is located behind it.

Sections are used to depict the internal surfaces of an object in order to avoid a large number dashed lines that can overlap each other with a complex internal structure of the object and make it difficult to read the drawing.

To make a cut, you must: mentally draw a cutting plane in the right place on the object (Fig. 1.4.1, a); mentally discard the part of the object located between the observer and the cutting plane (Fig. 1.4.1, b), project the remaining part of the object onto the corresponding projection plane, perform the image either in place of the corresponding view, or in the free field of the drawing (Fig. 1.4.1 , in); shade a flat figure lying in a cutting plane; if necessary, give the designation of the section.

Depending on the number of secant planes, the cuts are divided into simple - with one secant plane, complex - with several secant planes.

Depending on the position of the cutting plane relative to the horizontal projection plane, the sections are divided into:
horizontal - cutting plane is parallel to the horizontal projection plane;
vertical - cutting plane is perpendicular to the horizontal projection plane;
inclined - the cutting plane makes an angle with the horizontal projection plane that is different from the right one.

A vertical section is called frontal if the cutting plane is parallel to the frontal projection plane, and profile if the cutting plane is parallel to the profile projection plane.

Complex cuts are stepped if the secant planes are parallel to each other, and broken, if the secant planes intersect with each other.

The cuts are called longitudinal if the cutting planes are directed along the length or height of the object, or transverse if the cutting planes are directed perpendicular to the length or height of the object.

Local incisions are used to identify internal structure object in a separate limited place. The local section is highlighted in the view by a solid wavy thin line.

The rules provide for the designation of cuts.

The position of the cutting plane is indicated by an open section line. The start and end strokes of the section line must not cross the contour of the corresponding image. On the initial and final strokes, you need to put arrows indicating the direction of the gaze (Fig. 1.4.2). Arrows should be applied at a distance of 2 ... 3 mm from the outer end of the stroke. With a complex cut, the strokes of an open section line are also carried out at the kinks of the section line.

Near the arrows indicating the direction of view from outside the angle formed by the arrow and the stroke of the section line, capital letters of the Russian alphabet are applied on the horizontal line (Fig. 1.4.2). Letter designations are assigned in alphabetical order without repetitions and without gaps, with the exception of the letters I, O, X, b, s, b.

The cut itself must be marked with an inscription of the type "A - A" (always in two letters, through a dash).

If the cutting plane coincides with the plane of symmetry of the object, and the cut is made in the place of the corresponding view in the projection connection and is not separated by any other image, then for horizontal, vertical and profile cuts it is not necessary to mark the position of the cutting plane and the cut should not be accompanied by an inscription. On fig. 1.4.1 the frontal section is not marked.

Simple oblique cuts and complex cuts are always indicated.

Consider typical examples of the construction and designation of cuts in the drawings.

On fig. 1.4.3 made a horizontal section "A - A" in place of the top view. A flat figure lying in a cutting plane - a section figure - is shaded, and visible surfaces,

located under the cutting plane, are limited by contour lines and are not shaded.

On fig. 1.4.4, a profile section is made in place of the left view in projection connection with the main view. The cutting plane is the profile plane of symmetry of the object, so the cut is not indicated.

On fig. 1.4.5, a vertical section "A - A" is made, obtained by a secant plane that is not parallel to either the frontal or profile projection planes. Such sections can be built in accordance with the direction indicated by the arrows (Fig. 1.4.5), or placed in any convenient location drawing, as well as with a rotation to the position corresponding to that adopted for this subject in the main image. In this case, the sign O is added to the section designation.

The inclined section is made in fig. 1.4.6.

It can be drawn in a projection relationship in accordance with the direction indicated by the arrows (Fig. 1.4.6, a), or placed anywhere in the drawing (Fig. 1.4.6, b).

In the same figure, in the main view, a local section is made showing through cylindrical holes on the base of the part.

On fig. 1.4.7, in place of the main view, a complex frontal stepped section is drawn, made by three frontal parallel planes. When performing a stepped cut, all parallel cutting planes are mentally combined into one, i.e., a complex cut is drawn up as a simple one. On a complex section, the transition from one cutting plane to another is not reflected.

When constructing broken sections (Fig. 1.4.8), one secant plane is placed parallel to any main projection plane, and the second secant plane is rotated to coincide with the first.

Together with the cutting plane, the section figure located in it is rotated and the cut is made in the rotated position of the section figure.

The connection of a part of a view with a part of a section in one image of an object according to GOST 2.305-68 is allowed. In this case, the boundary between the view and the section is a solid wavy line or a thin line with a break (Fig. 1.4.9).

If half of the view and half of the section are connected, each of which is a symmetrical figure, then the line separating them is the axis of symmetry. On fig. 1.4.10, four images of the part are made, and on each of them half of the view is connected to the half of the corresponding section. On the main view and the left view, the section is located to the right of vertical axis symmetry, and in top and bottom views - to the right of the vertical or below the horizontal axis of symmetry.

If the contour line of the object coincides with the axis of symmetry (Fig. 1.4.11), then the border between the view and the section is indicated wavy line, which is carried out so as to preserve the image of the edge.

Hatching of the section figure included in the section must be carried out in accordance with GOST 2.306-68. Non-ferrous, ferrous metals and their alloys are indicated in cross-section by hatching with solid thin lines with a thickness from S / 3 to S / 2, which are drawn parallel to each other at an angle of 45 ° to the lines of the drawing frame (Fig. 1.4.12, a). Hatching lines can be applied with an inclination to the left or right, but in the same direction on all images of the same detail. If the hatching lines are drawn at an angle of 45° to the lines of the drawing frame, then the hatching lines can be placed at an angle of 30° or 60° (Fig. 1.4.12, b). The distance between parallel lines hatching is chosen in the range from 1 to 10 mm, depending on the area of the hatching and the need to diversify the hatching.

Non-metallic materials (plastics, rubber, etc.) are indicated by hatching by intersecting mutually perpendicular lines (hatching "in a cage"), inclined at an angle of 45 ° to the frame lines (Fig. 1.4.12, c).

Consider an example. Having completed the frontal section, we will connect half of the profile section with the half of the left view of the object given in Fig. 1.4.13, a.

Analyzing given image object, we come to the conclusion that the object is a cylinder with two through prismatic horizontal and two vertical internal holes,

of which one has the surface of a regular hexagonal prism, and the second has a cylindrical surface. The lower prismatic hole intersects the surface of the outer and inner cylinder, and the upper tetrahedral prismatic hole intersects the outer surface of the cylinder and inner surface hexagonal prismatic hole.

The frontal section of the object (Fig. 1.4.13, b) is performed by the frontal plane of symmetry of the object and is drawn in place of the main view, and the profile section is made by the profile plane of the symmetry of the object, therefore, neither one nor the other needs to be designated. The left view and the profile section are symmetrical figures, their halves could be delimited by the axis of symmetry, if not for the image of the edge of the hexagonal hole coinciding with the axial line. Therefore, we separate the part of the view to the left of the profile section with a wavy line, depicting most incision.

The image of a figure obtained by mentally dissecting one or more planes, provided that only what is in the cutting plane is shown in the drawing, is called a section. The section differs from the section in that it depicts only what directly falls into the cutting plane (Fig. 1.5.1, a). The section, like the section, is a conditional image, since the figure of the section does not exist separately from the object: it is mentally torn off and depicted in the free field of the drawing. Sections are part of the section and exist as independent images.

Sections that are not part of the section are divided into removed (Fig. 1.5.1, b) and superimposed (Fig. 1.5.2, a). Preference should be given to rendered sections, which can be placed in a section between parts of the same image (Fig. 1.5.2, b).

According to the shape of the section, they are divided into symmetrical (Fig. 1.5.2, a, b) and asymmetrical (Fig. 1.5.1, b).

The contour of the rendered section is drawn with solid main lines, and the contour of the superimposed one is drawn with solid thin ones, and the contour of the main image at the location of the superimposed section is not interrupted.

Section designation in general case similar to the designation of sections, i.e., the position of the cutting plane is displayed by section lines, on which arrows are applied, giving the direction of view and denoted by the same capital letters Russian alphabet. In this case, an inscription of the type "A - A" is made above the section (see Fig. 1.5.2, b).

For asymmetric superimposed sections or made in a gap in the main image, the section line with arrows is drawn, but they are not marked with letters (Fig. 1.5.3, a, b). Superimposed symmetrical section (see Fig. 1.5.2, a), symmetrical section made in the break of the main image (see Fig. 1.5.2, b), remote symmetrical section made along the trace of the secant plane (see Fig. 1.5 .1, a), are drawn up without drawing a section line.

If the cutting plane passes through the axis of the surface of revolution that bounds the hole or recess, then the contour of the hole or recess is drawn completely (Fig. 1.5.4, a).

If the cutting plane passes through a through non-circular hole and the section is obtained consisting of individual independent parts, then cuts should be applied (Fig. 1.5.4, b).

Oblique sections are obtained from the intersection of the subject inclined plane, constituting with the horizontal plane of projections an angle other than a right one. In the drawing, inclined sections are performed according to the type of extended sections. The oblique section of an object must be built as a set of oblique sections of its constituents. geometric bodies. The construction of inclined sections is based on the use of the method of replacing projection planes.

When drawing an oblique section, it is necessary to determine which surfaces that bound the object are cut by the cutting plane, and which lines are obtained from the intersection of these surfaces with this cutting plane. On fig. 1.5.5 the inclined section "A - A" is built. The cutting plane crosses the base of the object along a trapezoid, the inner and outer cylindrical surfaces - along ellipses, the centers of which lie on the main vertical axis of the object. Reading the shape of an oblique section is made easier if you plot the plan view of the oblique section as an overlay section.

When making drawings, in some cases it becomes necessary to build an additional separate image of any part of the object that requires explanations regarding the shape, dimensions or other data. Such an image is called a callout. It is usually performed enlarged. A callout can be laid out as a view or as a section.

When constructing a remote element, the corresponding place in the main image is marked with a closed solid thin line, usually an oval or a circle, and denoted capital letter Russian alphabet on the shelf of the leader line. The external element is recorded according to type A (5: 1). On fig. 1.6.1 shows an example of a remote element. It is placed as close as possible to the corresponding place on the image of the subject.

While doing various images subject GOST 2.305-68 recommends the use of some conventions and simplifications, which, while maintaining the clarity and clarity of the image, reduce the amount of graphic work.

If the view, section or section are symmetrical figures, then only half of the image or slightly more than half of the image can be drawn, limiting it with a wavy line (Fig. 1.7.1).

Simplification is allowed to depict cut lines and transition lines; instead of curved curves, arcs of a circle and straight lines are drawn (Fig. 1.7.2, a), and a smooth transition from one surface to another should be shown conditionally (Fig. 1.7.2, b) or not shown at all (Fig. 1.7.2, c ).

It is allowed to depict a slight taper or slope enlarged. On those images where the slope or taper is not clearly detected, only one line is drawn, corresponding to the smaller size of the element with a slope (Fig. 1.7.3, a) or the smaller base of the cone (Fig. 1.7.3, b).

When making cuts, non-hollow shafts, handles, screws, dowels, and rivets are shown undissected. Balls are always depicted uncut.

Elements such as spokes, thin walls, stiffeners are shown unshaded in the section if the cutting plane is directed along the axis or long side of such an element (Fig. 1.7.4). If there is a hole or recess in such elements, then a local incision is made (Fig. 1.7.5, a).

Holes located on a round flange and not falling into the cutting plane are shown in section as if they were in the cutting plane (Fig. 1.7.5, b).

To reduce the number of images, it is allowed to depict the part of the object located between the observer and the cutting plane as a thickened dash-dotted line (Fig. 1.7.6). In more detail, the rules for the image of objects are set out in GOST 2.305-68.

To construct a visual image of an object, we use axonometric projections. It can be done according to its complex drawing. Using Fig. 1.3.3, let's build a standard rectangular isometry of the object depicted on it. Let's use the given distortion coefficients. Let's take the location of the origin of coordinates (point O) - in the center of the lower base of the object (Fig. 1.8.1). Having drawn the isometric axes and set the image scale (MA 1.22: 1), we mark the centers of the circles of the upper and lower bases of the cylinder, as well as the circles that bound the T-shaped cutout. We draw ellipses, which are isometries of circles. Then we draw lines parallel to the coordinate axes that limit the cutout in the cylinder. Isometry of the line of intersection of a through cylindrical hole,

whose axis is parallel to the Oy axis with the surface of the main cylinder, we build on separate points, using the same points (K, L, M and symmetrical to them) as when constructing the view on the left. Then we remove the auxiliary lines and finally outline the image, taking into account the visibility of individual parts of the object.

To construct an axonometric image of an object, taking into account the cut, we use the conditions of the problem, the solution of which is shown in Fig. 1.4.13, a. In a given drawing, to build a visual image, we note the position of the projections coordinate axes and on soy Oz we mark the centers 1,2,..., 7 figures of the object located in horizontal planes G1", T"2, ..., G7", these are the upper and lower bases of the object, the bases of the internal holes. For transfer internal forms of the object, we will make a cutout of 1/4 of the part of the object coordinate planes xOz and yOz.

flat figures, obtained in this case, have already been built on a complex drawing, since they are halves of the frontal and profile sections of objects (Fig. 1.4.13, b).

We begin the construction of a visual image by drawing the axes of dimetry and indicating the scale MA 1.06: 1. On the z axis, we mark the position of the centers 1, 2, ..., 7 (Fig. 1.8.2, a); we take the distances between them from the main view of the object. Through the marked points we draw the axes of dimetry. Then we build in dimetry the figures of the section, first in the xOz plane, and then in the yOz plane. We take the dimensions of the coordinate segments from the integrated drawing (Fig. 1.4.13); at the same time, the dimensions along the y-axis are halved. We carry out hatching of sections. The angle of inclination of hatching lines in axonometry is determined by the diagonals of parallelograms built on axonometric axes, taking into account the distortion coefficients. On fig. 1.8.3, but an example of choosing the direction of hatching in isometry is given, and in fig. 1.8.3, b - in dimetry. Next, we build ellipses - the dimetry of circles located in horizontal planes (see Fig. 1.8.2, b). We spend contour lines outer cylinder, inner vertical holes, we build the base of these holes (Fig. 1.8.2, c); we draw visible lines of intersection of horizontal holes with the outer and inner surfaces.

Then we remove the auxiliary construction lines, check the correctness of the drawing and outline the drawing with lines of the required thickness (Fig. 1.8.2, d).

The image of the visible part of the surface of the object facing the observer is called the view.

The main views are usually located in a projection relationship with each other. In this case, the name of the views on the drawing does not need to be inscribed.

If any view is displaced relative to the main image, its projection connection with the main view is broken, then an “A” type inscription is made above this view (Fig. 1.2.1).

If the views are in a projection relationship with each other, but are separated by any images or are located on more than one sheet, then an inscription of the “A” type is also made above them. An additional view is obtained by projecting an object or part of it onto an additional projection plane that is not parallel to the main planes (Fig. 1.2.3). Such an image must be performed in the case when any part of the object is not depicted without distorting the shape or size on the main projection planes.

An additional projection plane in this case can be located perpendicular to one of the main projection planes.

and for the image associated with the additional view, you need to put an arrow indicating the direction of the view, with the corresponding letter designation.

The secondary view can be rotated while maintaining the position adopted for this item in the main image. In this case, a sign must be added to the inscription (Fig. 1.2.3, c).

A local view is an image of a separate, limited place on the surface of an object (Fig. 1.2.4).

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Topic 3. Construction of the third type of object according to two data

On the top view in the form of a triangle, they can be depicted (Fig. 1.3.1, a): triangular prism 1, triangular 2 and quadrangular 3 pyramids, cone of revolution 4.

The shape of a circle can be seen from above (Fig. 1.3.1, c): ball 11, cone 12 and cylinder 13 of rotation, other surfaces of rotation 14.

The top view in the form of a regular hexagon has a regular hexagonal prism (Fig. 1.3.1, d), which limits the surfaces of nuts, bolts and other parts.

Having determined the shape of individual parts of the surface of an object, one must mentally imagine their image in the left view and the entire object as a whole.

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