What paper is best for technical drawings? Drawing

Technical drawing is a visual image that has the basic properties of axonometric projections or a perspective drawing, made without the use of drawing tools, on a visual scale, in compliance with proportions and possible shading of the form.

Technical drawings have long been used by people to reveal creative idea. Take a closer look at Leonardo da Vinci’s drawings, which so fully reveal the design features of a device or mechanism that you can use them to make drawings, develop a project, or manufacture an object in material (Fig. 123).

Engineers, designers, architects, when designing new models of equipment, products, structures, use technical drawing as a means of fixing the first, intermediate and final options technical solutions. In addition, technical drawings serve to verify the correct reading of a complex shape shown in a drawing. Technical drawings are necessarily included in the set of documentation prepared for transfer to foreign countries. They are used in technical data sheets of products.

Rice. 123. Technical drawings by Leonardo da Vinci

Rice. 124. Technical drawings of parts made of metal (a), stone (b), glass (c), wood (d)

A technical drawing can be performed using the central projection method (see Fig. 123), and thereby obtain a perspective image of an object, or the parallel projection method (axonometric projections), constructing a visual image without perspective distortions (see Fig. 122).

Technical drawing can be performed without revealing the volume by shading, with shading of the volume, as well as conveying the color and material of the depicted object (Fig. 124).

In technical drawings, it is allowed to reveal the volume of objects using the techniques of shading (parallel strokes), scribbling (strokes applied in the form of a grid) and dot shading (Fig. 125).

The most commonly used technique for identifying the volume of objects is shaking.

It is generally accepted that rays of light fall on an object from the top left (see Fig. 125). Illuminated surfaces are not shaded, while shaded surfaces are covered with shading (dots). When shading shaded areas, strokes (dots) are applied with the smallest distance between them, which makes it possible to obtain denser shading (dot shading) and thereby show shadows on objects. Table 11 shows examples of identifying the shape of geometric bodies and parts using shattering techniques.

Rice. 125. Technical drawings revealing volume by shading (a), scribbling (b) and dot shading (e)

11. Shading of the form using shading techniques

Technical drawings are not metrically defined images unless they are marked with dimensions.

To simplify the work of making visual images, technical drawings are often used.

Technical drawing- this is an image made by hand, according to the rules of axonometry, observing proportions by eye. In this case, the same rules are followed as when constructing axonometric projections: the axes are placed at the same angles, the dimensions are laid along the axes or parallel to them.

It is convenient to make technical drawings on checkered paper. Figure 70, a shows the construction using the cells of a circle. First on center lines four strokes are applied from the center at a distance equal to the radius of the circle. Then four more strokes are applied between them. Finally, draw a circle (Fig. 70, b).

It is easier to draw an oval by inscribing it in a rhombus (Fig. 70, d). To do this, as in the previous case, first strokes are applied inside the rhombus, outlining the shape of an oval (Fig. 70, c).

Rice. 70. Constructions that facilitate the execution of technical drawings

To better display the volume of an object, shading is applied to technical drawings (Fig. 71). In this case, it is assumed that the light falls on the object from the top left. Illuminated surfaces are left light, and shaded ones are covered with shading, which is more frequent the darker the surface of the object.

Rice. 71. Technical drawing of a part with shading

1. What is the difference technical drawing from axonometric projection?
2. How can you determine the volume of an object in a technical drawing?
3. Draw in workbook: a) axes of frontal dimetric and isometric projection (following the example in Figure 61); b) a circle with a diameter of 40 mm and an oval corresponding to the image of the circle in an isometric projection (following the example in Figure 70).
4. Complete a technical drawing of the part, two views of which are given in Figure 62.
5. As instructed by the teacher, complete a technical drawing of a model or part from life.

Task conditions: complete a sketch and technical drawing of the part from life (Fig. 10.20). Do the work on two sheets of paper.

As can be seen from Fig. 10.20, the part is a flange intended for detachable connection of pipelines. It is attached to the counter part using six bolts, as evidenced by the presence of unthreaded holes. The connection with the subsequent part is threaded. The flange is made of metal, which has a yellow tint characteristic of brass.

Before proceeding with the sketch, in accordance with the recommendations and. 10.2, let's make plan for its implementation:

1. Planning the working area of ​​the drawing and drawing dimensional rectangles.

Work orderA. Performing a sketch

• 1. If you do not take into account the six cylindrical holes of small diameter, this flange is a collection of coaxial conical and cylindrical surfaces. Therefore, to depict it, it would be enough to give a connection of half of the front view (to show the external shape of the part) and half of the frontal section (to reveal the shape of the hole). Taking into account the fact that such parts are usually turned on a lathe, the axis of rotation should be positioned horizontally. However, the presence of six cylindrical holes requires the addition of one more view (on the left) to demonstrate the principle of their location.
• 2. Based on the analysis, we conclude that required images the parts will be inscribed in the overall rectangle and square, and the sides of the rectangle, as can be seen from Fig. 10.20, differ from each other slightly. The approximate aspect ratio of the overall rectangle can be taken as 10: 11.

We draw the overall rectangle and square on the working surface of the drawing so that there is enough space around for setting dimensions (Fig. 10.21a).

• 3. We examine the shape of the depicted flange and draw by hand the connection of half of the front view and half of the frontal section (Fig. 10.216). It was already noted above that in the case under consideration, the view on the left is necessary only to determine the position of the cylindrical holes. Therefore, it is advisable to build inside the overall square local species on the location of the holes (see Fig. 10.216).
• 4. We put down dimension lines in accordance with the recommendations of clause 10.2, taking into account the sequence of processing the workpiece. All dimensions related to the outer surface are concentrated on the side of the view, and all dimensions characterizing the internal structure of the part are concentrated on the side of the cut (Fig. 10.21 c).

Rice. 10.21a - drawing dimensional rectangles

Rice. 10.216

Rice. 10.21 in - placing dimension lines

Rice. 10.21 g - setting dimensional numbers and drawing up a sketch

Rice. 10.22

• 5. We measure the part using available measuring tools (calipers, rulers, thread gauges). We place the specific digital data obtained during the measurement in the places prepared in advance for them (Fig. 10.21 d).
• 6. Finally, we prepare the sketch as a graphic design document. To do this, fill in the main inscription:
  • - enter the name of the part “Flange”;
  • - find in Appendix 5 the designation of a suitable brand of brass and enter it in the appropriate column;
  • - put a dash in the “Scale” column;
  • - since the task also requires a technical drawing of the flange, in the “Sheets” column we indicate total sheets in work - 2;
  • - assign the corresponding alphanumeric code to the drawing.

B. Execution of technical drawing

1. We will perform technical drawing according to the rules of isometric projection. In this case, we will position the axis of rotation of the flange in the same way as in the sketch, along the X axis.

In the case under consideration, the flange is shaped like a body of revolution. As a result, it is entirely acceptable to give it full cut, supplemented with images of cylindrical holes of small diameter.

The result of the constructions is shown in Fig. 10.22.

2. In conclusion, we draw up the drawing in the same way as the sketch in Fig. 10.21 g, additionally adding the sheet number - 2 - to the 1st Rafa of “Sheets”.

Technical drawing.pptx

Construction of a technical drawing geometric body, like any object, start from the base. For this purpose, first draw the axes of the flat figures lying at the base of these bodies.

The axes are constructed using the following graphic technique. Arbitrarily choose a vertical line, set any point on it and draw two intersecting lines through it at angles of 60° to the vertical line (Fig. 82, a). These straight lines will be the axes of the figures whose technical drawings need to be completed.

Let's look at some examples. Suppose you need to perform a technical drawing of a cube. The base of the cube is a square with side equal to a. We draw the lines of the sides of the square parallel to the constructed axes (Fig. 82, b and c), choosing their value approximately equal to a. From the vertices of the base we draw vertical lines and on them we lay out segments approximately equal to the height of the polyhedron (for a cube it is equal to a). Then we connect the vertices, completing the construction of the cube (Fig. 82, d). Drawings of other objects are constructed in the same way.

Rice. 82

It is convenient to construct technical drawings of a circle by fitting them into a drawing of a square (Fig. 83). The picture of a square can be conditionally taken as a rhombus, and the picture of a circle as an oval. An oval is a figure consisting of circular arcs, but in technical drawing it is done not with a compass, but by hand. The side of the rhombus is approximately equal to the diameter of the depicted circle d (Fig. 83, a).

Rice. 83

In order to fit an oval into a rhombus, arcs are first drawn between points 1-2 and 3-4 (Fig. 83, b). Their radius is approximately equal to the distance of A3 (A4) and B1 (B2). Then arcs 1-3 and 2-4 are drawn (Fig. 83, c), completing the construction of the technical drawing of the circle.

To depict a cylinder, it is necessary to construct drawings of its lower and upper bases, placing them along the axis of rotation at a distance of approximately equal to height cylinder (Fig. 83, d).

To construct the axes of figures located not in the horizontal plane of projections, as given in Figure 83, but in vertical planes, it is enough to draw one straight line on a taken vertical line through an arbitrarily chosen point, directing it down to the left for figures parallel to the frontal plane of projections, or down to the right - for figures parallel to the profile plane of projections (Fig. 84, a and b).

Rice. 84

The placement of ovals when performing technical drawings of circles located in different coordinate planes is given in Figure 85, where 1 is a horizontal plane, 2 is frontal and 3 is profile.

Rice. 85

It is convenient to make technical drawings on checkered paper (Fig. 86).

Rice. 86

To give the technical drawing greater clarity, use various ways conveying the volume of an object. They can be linear shading (Fig. 87, a), shading (hatching with a “check” - Fig. 87, b), dot shading (Fig. 87, c), etc. (see also Fig. 88). It is assumed that light falls on the surface from the top left. Illuminated surfaces are left light, and shaded ones are covered with strokes, which are thicker where one or another part of the surface of the object is darker.

Rice. 87

Rice. 88

Figure 89 shows technical drawings of more complex parts using shading, shading and spot shading.

Rice. 89 1. What drawing is called technical? 2. What methods of conveying the volume of objects are used in technical drawing?

Option 1. Technical drawing of the part

Using the drawing in rectangular projections, make a technical drawing of one of the parts (Fig. 90).

Rice. 90

Requirements for the preparation of practical work

When drawing models, approximate methods of their construction are used.

Think about the layout of the drawing. Make technical drawings of models in A 4 (A3) format, by hand from nature (or according to complex drawings), without using a drawing tool, apply (hatching), scribbling and quarter cutting. Save construction lines.

A technical drawing is a visual image made according to the rules for constructing axonometric projections (by hand or using drawing tools) using chiaroscuro. The goals of performing a technical drawing are to test the student’s ability to read a particular drawing and consolidate the skills of making visual images.

Making visual images, especially by hand, without first constructing axonometric projections, develops the eye, spatial understanding of the shapes of an object, the ability to analyze these shapes and visually depict them. Special meaning I received a technical drawing in connection with the introduction of technical aesthetics requirements into the design process.

Technical drawings are usually carried out when taking sketches from nature (the drawing is done by hand) and when detailing the drawing general view(the drawing is done using drawing tools).

In most cases, rectangular iso- and dimetric projections are used as the basis for a technical drawing, which, along with clarity, are quite simple in their implementation.

To construct visual images in dimetry, it is better to use the position of the axes, providing for a “left” coordinate system (Fig. 6.19, a, b). Chiaroscuro, which is an additional means of conveying the volume of an object, is used to give the axonometric image greater expressiveness (Fig. 6.19, b). In order to perform axonometric images of objects taking into account chiaroscuro, let us briefly get acquainted with the basic rules of these constructions.

Chiaroscuro called the distribution of light on the surface of an object. Depending on the shape of the object, rays of light falling on

it, are distributed unevenly over its surface, due to which chiaroscuro creates the expressiveness of the image - relief and volume.

The following elements of chiaroscuro can be noted (Fig. 6.20): light, penumbra and shadow (own and incident). There is a reflex on the shaded part, and a glare on the illuminated part.

Light - illuminated part of the surface of an object. The illumination of a surface depends on the angle at which light falls on this surface. light rays. The most illuminated surface is the one that is perpendicular to the direction of the light rays.

Penumbra - moderately illuminated part of the surface. The transition from light to penumbra on faceted surfaces can be abrupt, but on curved surfaces it is always gradual. The latter is explained by the fact that the angle of incidence of light rays on neighboring parts also changes gradually.

Own shadow - part of the surface of an object that is not reached by light rays.

Falling shadow appears when an object is placed in the path of light rays, which casts a falling shadow on the surface behind it.

Reflex - highlighting one's own shadow by illuminating the shadow side of an object by reflected rays from surrounding illuminated objects or surfaces of a given object.

Blik

Contour of one's own shadow

Reflex

Drop Shadow Outline

A shadow of one's own

In technical drawings, chiaroscuro is usually depicted in a simplified manner. The subject is usually depicted against a conventional background, isolated from environment; light on an object is depicted as a bright spot, without taking into account the dependence of the illumination of parts of the object on the angle of incidence of the light rays and distance from the light source. An example of such a simplified image of chiaroscuro is shown in Figure 6.19, b.

Sometimes technical drawings are performed with even greater simplification: only their own shadow is shown, and the falling shadow is not shown anywhere. This simplification greatly facilitates the construction, but the expressiveness of the image is lost.

Thus, to perform chiaroscuro in a drawing, you need to know the laws of constructing shadows. Every shadow has its own geometric shape, the construction of which can be performed using descriptive geometry methods. To construct shadow contours, you need to know the nature of the light rays and their direction.

When performing technical drawings, it is customary to use sunlight when the rays are parallel to each other, and their direction is from above, from left to right. This direction corresponds to the natural one when the light is on workplace falls from the left side.

For uniformity in construction, the rays of light are usually directed diagonally across the cube, as shown in Fig. 6.21, where the direction of light rays 5 is given for isometric (Fig. 6.21, A) and two dimetric projections with the “right” (Fig. 6.21, b) and “left” (Fig. 6.21, V) coordinate system.

Constructing the contour of your own shadow (the line separating the illuminated part of the surface from the unlit) is reduced to constructing

6 )

line change MY touching the ray surface 5 with the surface of the object (Fig. 6.22), and constructing the contour of the falling shadow - to constructing a line M N b intersection of the radial surface 5 with the plane R(or with the surface of any object).

By radial surface (or plane) is meant the surface that wraps given body, with generatrices drawn parallel to the rays of light.

In Figure 6.23, a, b, V, d shows the construction of shadow contours for a prism, pyramid, cylinder and cone. For these constructions, it is necessary to know not only the direction of the light rays, but also the direction of their 5 secondary projections. Constructing the contour of a falling shadow comes down to constructing the intersection points of light rays drawn through the contour of an object with the horizontal plane on which the object stands.

For example, dot L r the contour of the falling shadow of the prism is constructed as the point of intersection of ray 5 with the secondary projection 5 of this ray.

Two planes T and 0, tangents to the cylinder, allow you to construct the contour of your own shadow L V and the outline of the falling shadow In A. The falling shadow from the upper base of the cylinder is constructed by points / 2

To draw the outline of your own shadow AB cone, you first need to construct a falling shadow on the plane of its base (construct a point A r), and then draw a tangent/!^ from this point

to the base of the cone. Dot B=B p and defines the generator L V cone, which is the contour of its own shadow.

If there is another object or surface in the path of the ray surface (or plane), then the contour of the falling shadow is built on this object as shown in Fig. 6.24, where the falling shadow is built on the plane of the base of the prism and on part of the cylindrical surface (9. The construction order is clear from the drawing.

Chiaroscuro can be rendered with a pencil, pen (ink) or wash (diluted ink or watercolor). In technical drawing, a pencil is usually used to perform shading, shading or scribbling.

The shading is in the covering various parts drawing with strokes (without using a drawing tool). The desired tone is achieved by the frequency and thickness of strokes. Stroke length

should not be very large, since it is difficult to make long strokes. In Fig. 6.25, 6.26 show examples of shading on various surfaces.

The direction of the strokes must be consistent with the shape of the depicted object (see Fig. 6.25, a B C D), since strokes applied “according to form” help to convey and perceive this form.

Shading is a type of shading where the strokes are placed very close to each other so that they merge. Sometimes the strokes are rubbed with a finger or shading.

Engraving is special kind hatching done using drawing tools. This method of performing chiaroscuro is most often used in technical drawing, despite the fact that using it it is impossible to obtain smooth transitions from light to dark on curved surfaces. Examples of scratching on various surfaces are shown in Fig. 6.27, 6.28, 6.29, 6.30, in Fig. 6.28 - only axonometric image.

It should be noted that the means of conveying volume should be used in technical drawings carefully and economically, without making such an image an end in itself. In Fig. Figure 6.28 shows an example of conveying the shape of an object without applying a shadow.