Designation of the dimensions of the circle in the drawing. Drawing sizes and extreme deviations. Basic Drawing Dimensioning Guidelines
The basis for determining the size of the product and its elements are the dimensional numbers printed on the drawing. Dimensions always indicate true, regardless of the scale and accuracy of the image. Sizes must be assigned and marked so that they can be used to make the part without resorting to calculations.
The sizes should be the minimum quantity, but sufficient for the manufacture and control of the product. The absence of at least one of the dimensions makes the drawing practically unsuitable. Dimensions should be applied so that when reading them there are no ambiguities or questions. It should be remembered that the drawing is read in the absence of the author.
According to GOST 2.307-2011 - "Application of dimensions and maximum deviations" linear dimensions the drawing is given in millimeters, without a unit designation. Angular dimensions indicate in degrees, minutes, seconds with the unit designation. Each size is applied on the drawing, in the title block only once, it is unacceptable to repeat it.
When specifying the dimensions of rectilinear segments, dimension lines are drawn parallel to these segments at a distance of at least 10 mm from the contour line and 7 mm from each other, and extension lines are drawn perpendicular to the dimension lines. Extension lines should extend beyond the ends of the arrows of the dimension line by 1 ... 5 mm. The arrow of the dimension line should have a length of at least 2.5 mm and an angle at the apex of about 20 ° (Figure 3.1). The size and shape of the arrows should be the same throughout the drawing.
3.2. Dimensioning
In the drawings of parts, dimensions are laid down, based on the manufacturing technology of this part and from which surfaces this part is in contact with other parts of the assembly unit.
This affects the choice of design base.
Basing called giving the workpiece the desired position relative to the selected coordinate system.
Base called a surface or combination of surfaces, an axis or point belonging to a product or workpiece, and used for basing.
Design base - the base used to determine the position of the part or assembly unit in the product.
Basic Dimensioning Rule - grouping of sizes related to one geometric element in one image, on the one in which this element is most clearly represented. It is not always possible to accomplish this, but we always strive for this.
When specifying the size of the angle, the dimension line is drawn in the form of an arc with the center at its apex, and extension lines - radially (Figure 3.2).
Figure 3.3
As you can see, smaller dimensions should be placed closer to the contour of the part, the number of intersections of dimension and extension lines will be reduced, which will facilitate reading the drawing.
The dimension line is drawn with a break if on one side of the image it is not possible to draw an extension line, for example, in the case of combining view and section (Figure 3.4, but), and also, if the view or section of a symmetrical object is depicted only to the axis or with a break (Figure 3.4, b) A break in the dimension line is made further than the axis or line of the break in the object.
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| but | b |
Figure 3.4
Dimension lines are allowed to be cut off in the following cases:
- when specifying the size of the diameter of the circle; at the same time, a break in the dimension line is made further than the center of the circle (Figure 3.5);
- when applying dimensions from a base not shown in this drawing (Figure 3.6).
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| Figure 3.5 | Figure 3.6 |
The main line should be interrupted if it intersects with the arrow (Figure 3.5).
When displaying a product with a gap, the dimension line is not interrupted (Figure 3.7). The dimension number, in this case, must correspond to the full length of the part.
Figure 3.7
If it is not possible to place dimensional numbers and arrows between closely spaced solid main or thin lines, they are applied outside (Figure 3.8). Similarly, when applying the size of the radius, if the arrow does not fit between the curve and the center of the radius (Figure 3.9).
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| Figure 3.8 | Figure 3.9 |
It is allowed to replace the arrows with dots or serifs, drawn at an angle of 45 ° to the dimension lines, if it is impossible to place the arrow between the extension lines (Figure 3.10).
Figure 3.10
Dimensional numbers are not allowed to be divided or crossed by any lines of the drawing. At the point where the dimension number is applied, the axial, center lines or hatching lines are interrupted (Figure 3.11).
Figure 3.11
Dimensional numbers should be applied above the dimension line, as close as possible to its middle (Figure 3.12).
Figure 3.12
Dimensional numbers of linear dimensions at different slopes of dimension lines are positioned, as shown in Figure 3.13.
If it is necessary to apply dimensions to the shaded area, the corresponding dimensional number is applied to the line shelf - callouts.
Figure 3.13
Angular dimensions are applied as shown in Figure 3.14.
Figure 3.14
In the zone located above the horizontal center line, dimensional numbers are placed above the dimension lines from the side of their convexity, in the zone located below the horizontal center line - from the concavity of the dimension line.
Dimension numbers above parallel dimension lines should be staggered (Figure 3.15).
Figure 3.15
When specifying the size of the diameter in all cases, the sign Ø is preceded by the dimension number. In front of the dimension number of the diameter (radius) of the sphere, the O (Ø) sign is also applied without the inscription “Sphere” (Figure 3.16).
Figure 3.16
If it is difficult to distinguish a sphere from other surfaces in the drawing, it is allowed to put the word “Sphere” or the sign “O”, for example, “Sphere Ø 18, OR12”. The diameter of the sign of the sphere is equal to the height of the dimensional numbers in the drawing.
The dimensions of the square are applied as shown in the drawing (Figure 3.17).
Figure 3.17
The height of the sign should be equal to the height of the dimensional numbers in the drawing.
When applying the size of the radius, a capital letter is placed in front of the size number R . With a larger radius, the center can be brought closer to the arc, in this case, show the dimension line of the radius with a kink at an angle of 90 ° (Figure 3.18). If it is not required to indicate the dimensions that determine the position of the center of the arc of a circle, then the dimension line of the radius may not be brought to the center and offset from the center (Figure 3.19).
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| Figure 3.18 | Figure 3.19 |
The radii of fillets, the size of which on the drawing scale is 1 mm or less, are not shown in the drawing and their dimensions are applied, as shown in Figure 3.20.
When drawing the size of the circular arc, the dimension line is drawn concentrically to the arc, and extension lines parallel to the bisector of the angle, and the “” sign is applied over the dimension number (Figure 3.21).
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| Figure 3.20 | Figure 3.21 |
Chamfer dimensions at an angle of 45 ° are applied as shown in Figure 3.22, but. A bevel is allowed at an angle of 45 °, the size of which on the drawing scale is 1 mm or less, not to be depicted and its dimensions indicated on the shelf of the line - leader, as shown in Figure 3.22, b.
The dimensions of chamfers having other angles are applied according to general rules - two linear dimensions or linear and angular dimensions (Figure 3.23).
The question of what dimensions should be applied on the drawing is decided taking into account the manufacturing technology of parts and manufacturing control.
As a rule, the dimensions of the full circles are set by the diameter, of incomplete circles by the radius.
When you want to set the distance between circles, for example, depicting holes, specify the distance between the centers of the circles and the distance from the center of any circle to one of the surfaces of the part.
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| but | b |
Figure 3.22
Figure 3.23
The surfaces from which the dimensions of other elements of the part are specified are called base surfaces or bases.
There are several ways to apply dimensions:
- from a common base (Figure 3.24); as the base surface, the left surface of the bar is selected, from which the dimensions of all holes are affixed.
Such a system has an advantage, but the dimensions are independent of each other, the error of one of them does not affect the others.
- from several databases (Figure 3.25);
- chain (Figure 3.26).
Figure 3.24
Figure 3.25
Figure 3.26
When applying dimensions that determine the distance between equally spaced identical elements of the product (for example, holes), it is recommended instead of dimensional chains to apply the size between adjacent elements and the size between the extreme elements in the form of the product of the number of gaps between the elements and the gap size (Figure 3.27).
With a large number of dimensions plotted from a common base, it is allowed to apply linear and angular dimensions, as shown in Figure 3.28, while drawing a common dimension line from the “0” mark and dimensioning numbers in the direction of extension lines at their ends.
Figure 3.27
Figure 3.28
It is allowed not to apply the dimensions of the conjugation radius of parallel lines on the drawing (Figure 3.29).
Figure 3.29
The external and internal contours of parts in the manufacture and control are measured separately, therefore, in the drawing, their dimensions should be applied separately (Figure 3.30).
Figure 3.30
It is recommended to group the dimensions related to the same structural element (groove, protrusion, hole, etc.) in one place, placing them in the image in which the geometric shape of this element is shown most fully (Figure 3.31).
Figure 3.31
If the part has fillets, the dimensions of the parts of the part are plotted without fillets, indicating the radii of fillets (Figure 3.32).
Figure 3.32
The dimensions of the symmetrically located elements of the product (except for the holes) are applied once without indicating their number, grouping, as a rule, in one place all sizes (Figure 3.33).
Figure 3.33
Identical elements located in different parts of the product (for example, holes) are considered as one element if there is no gap between them (Figure 3.34, but) or, if these elements are connected by thin solid lines (Figure 3.34, b) In the absence of these conditions, indicate the total number of elements (Figure 3.34, at).
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Figure 3.34. The dimensions of several identical product elements are usually applied once, indicating the number of these elements on the line shelf (Figure 3.35).
Figure 3.35
When applying the sizes of elements evenly spaced around the circumference (for example, holes), instead of the angular dimensions that determine the relative position of the elements, only their number is indicated (Figure 3.36 - 3.38).
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| Figure 3.36 | Figure 3.37 | Figure 3.38 |
When depicting a part in one projection, the size of its thickness or length is plotted, as shown in Figure 3.39.
Figure 3.39
Dimensions in the drawing are not allowed to be applied as closed circuitunless one of the sizes is indicated as reference.
Reference Dimensions - dimensions not to be performed according to this drawing and indicated for greater ease of use of the drawing.
Reference dimensions on the drawing are marked with a "*", and in the technical requirements are written "* Dimensions for reference." If all the dimensions on the drawing are for reference, they are not marked with the “*” sign, and “Dimensions for information” are written in the technical requirements.
TO reference dimensions The following sizes apply:
- one of the sizes of a closed dimensional chain (Figure 3.40);
- dimensions transferred from the drawings - blanks (Figure 3.41);
- dimensions that determine the position of the elements of the part to be processed according to another part (Figure 3.42);
Figure 3.40
Figure 3.41
Figure 3.42
- dimensions on the assembly drawing, which determine the limit positions of individual structural elements, for example, the piston stroke, the stroke of the valve stem of an internal combustion engine, etc .;
- dimensions on the assembly drawing, parts transferred from the drawing and used as installation and connection;
- overall dimensions on the assembly drawing, transferred from the drawings of parts or being the sum of the dimensions of several parts;
- dimensions of parts (elements) from long, shaped, sheet and other rolled products, if they are completely determined by the material designation given in the corresponding column of the main inscription (Figure 3.43).
Figure 3.43
Notes:
- Installation and connection are called dimensions that determine the size of the elements by which this product is installed at the installation site or attached to another product.
- Overall dimensions are dimensions that determine the maximum external (or internal) outlines of the product.
| Ra5 | Ra10 | Ra20 | Ra40 | Ra5 | Ra10 | Ra20 | Ra40 | Ra5 | Ra10 | Ra20 | Ra40 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 0,100 | 0,100 | 0,100 | 0,100 | 1,0 | 1,0 | 1,0 | 1,0 | 10 | 10 | 10 | 10 |
| 0,10 5 | 1,05 | 10,5 | |||||||||
| 0,110 | 0,110 | 1,1 | 1,1 | 11 | 11 | ||||||
| 0,115 | 1,15 | 11,5 | |||||||||
| 0,120 | 0,120 | 0,120 | 1,2 | 1,2 | 1,2 | 12 | 12 | 12 | |||
| 0,130 | 1,3 | 13 | |||||||||
| 0,140 | 0,140 | 1,4 | 1,4 | 14 | 14 | ||||||
| 0,150 | 1,5 | 15 | |||||||||
| 0,160 | 0,160 | 0,160 | 0,160 | 1,6 | 1 ,6 | 1,6 | 1,6 | 16 | 16 | 16 | 16 |
| 0,170 | 1,7 | 17 | |||||||||
| 0,1 80 | 0,180 | 1,8 | 1,8 | 18 | 18 | ||||||
| 0,190 | 1,9 | 19 | |||||||||
| 0,200 | 0,200 | 0,200 | 2,0 | 2,0 | 2,0 | 20 | 20 | 20 | |||
| 0,210 | 2,1 | 21 | |||||||||
| 0,220 | 0 ,220 | 2,2 | 2,2 | 22 | 22 | ||||||
| 0,240 | 2,4 | 24 | |||||||||
| 0,250 | 0,250 | 0,2 50 | 0,250 | 2,5 | 2,5 | 2,5 | 2,5 | 25 | 25 | 25 | 25 |
| 0,260 | 2,6 | 26 | |||||||||
| 0,280 | 0,280 | 2,8 | 2,8 | 28 | 28 | ||||||
| 0,300 | 3,0 | 30 | |||||||||
| 0,320 | 0,320 | 0,320 | 3,2 | 3,2 | 3,2 | 32 | 32 | 32 | |||
| 0,340 | 3,4 | 34 | |||||||||
| 0,360 | 0,360 | 3,6 | 3,6 | 36 | 36 | ||||||
| 0,380 | 3,8 | 38 | |||||||||
| 0,400 | 0,400 | 0,400 | 0,400 | 4,0 | 4,0 | 4,0 | 4,0 | 40 | 40 | 40 | 40 |
| 0,420 | 4,2 | 42 | |||||||||
| 0,450 | 0,450 | 4, 5 | 4,5 | 45 | 4 5 | ||||||
| 0,480 | 4,8 | 48 | |||||||||
| 0,500 | 0,500 | 0,500 | 5,0 | 5,0 | 5,0 | 50 | 50 | 50 | |||
| 0,530 | 5,3 | 53 | |||||||||
| 0,560 | 0,560 | 5,6 | 5,6 | 56 | 56 | ||||||
| 0,600 | 6,0 | 60 | |||||||||
| 0,630 | 0,630 | 0,630 | 0,630 | 6,3 | 6,3 | 6,3 | 6,3 | 63 | 63 | 63 | 63 |
| 0,670 | 6,7 | 67 | |||||||||
| 0,710 | 0,710 | 7,1 | 7,1 | 71 | 71 | ||||||
| 0,750 | 7, 8 | 75 | |||||||||
| 0,800 | 0,800 | 0,800 | 8,0 | 8,0 | 8,0 | 80 | 80 | 80 | |||
| 0,850 | 8,5 | 85 | |||||||||
| 0,900 | 0,900 | 9,0 | 9,0 | 90 | 90 | ||||||
| 0,950 | 9,5 | 95 | |||||||||
| 100 | 100 | 100 | 100 | 160 | 160 | 160 | 160 | 250 | 250 | 250 | 250 |
| 105 | 170 | 260 | |||||||||
| 110 | 110 | 180 | 280 | 280 | |||||||
| 120 | 190 | 300 | |||||||||
| 125 | 125 | 125 | 200 | 200 | 200 | 320 | 320 | 320 | |||
| 130 | 210 | 340 | |||||||||
| 140 | 140 | 220 | 220 | 360 | 360 | ||||||
| 150 | 240 | 380 |
According to the images of the object in the drawing, its size and the size of its individual parts are judged. The basis for this is dimensional numbers, regardless of the scale and accuracy of the images. The rules for applying dimensions in the drawings are established by GOST 2.307-68.
Dimensions in the drawings indicate dimensional numbers, dimensional and extension lines. Dimensional numbers in the drawings, as a rule, indicate in millimeters without indicating units of measurement. In cases where it is necessary to use other units of measurement of length, they are shown after the dimension number.
Dimensional numbers are applied over the dimension line, possibly closer to its middle. The gap between the dimension number and the dimension line should be about 1.0 mm. The height of the digits of dimensional numbers is at least 3.5 mm (Fig. 7).
The dimension line is drawn parallel to the segment, the size of which is applied above it. It is carried out between extension lines drawn perpendicularly to dimensional. Dimensional lines are allowed to be drawn directly to the lines of the visible contour, axial and center. In some cases, the dimension line may not be drawn perpendicular to the extension line (Fig. 8).
Dimension lines limit the arrows (Fig. 9).
In some cases, they are not carried out completely, but with a clipped arrow on one side (Fig. 10).
The size of the arrow is selected from the thickness of the solid thick main line adopted in the drawing. Within the same drawing, the size of the arrows should be as uniform as possible. It is not recommended to use contour, axial, center and extension lines as dimension lines.
If the length of the dimension line is small for the placement of the arrows, then the dimension line is continued beyond the extension lines, and the dimensions are applied, as shown in Fig. eleven.
Extension lines are drawn from the boundaries of measurements, they are auxiliary and are used to place dimension lines between them. Extension lines should, whenever possible, be located outside the image contour, perpendicular to the straight line segment, the size of which must be specified. Extension lines should extend beyond the ends of the arrows of dimension lines by 1-5 mm (Fig. 12). The minimum distance from the dimension line to the line parallel to it should be 10 mm, and between parallel dimension lines - 7 mm.
The angular dimensions in the drawings are given in degrees, minutes and seconds with the units. The size of the angle is applied over the dimension line, which is drawn in the form of an arc with the center at its apex. Extension lines in this case are drawn radially (Fig. 13).
At various slopes of the dimension lines, the dimensional numbers of linear dimensions are arranged as shown in Fig. 14a, and the angular dimensions are as shown in Fig. 14, b.
If the dimension line is in the area that is shaded in the drawing, the dimension numbers are applied on the shelves of the leader lines (Fig. 15).
If there is little space above the dimension line to write a dimension number or this place is occupied by other image elements and it is impossible to enter a dimension number into it, the dimension number is applied according to one of the options shown in Fig. sixteen.
In order to simplify a number of images and create conveniences for reading a drawing, the standard provides for the use of symbols in the form of letters of the Latin alphabet and graphic signs that are placed in front of dimensional numbers. In the drawings, signs and letters are used to indicate the diameter and radius, the length of the arc and square, the slope and taper, the sphere, the thickness and length of the part.
Before the dimension number of the diameter, the sign "Ø" is applied (Fig. 17).
Moreover, between the sign and the number no gaps are provided. For circles of small diameter, the dimension lines of the arrow and the size itself are plotted according to one of the options shown in Fig. 18.
In front of the dimension number of the arc radius, a sign in the form of an uppercase Latin letter R is always placed. The dimension line in this case is drawn towards the center of the arc and is limited to only one arrow resting on the arc or its extension (Fig. 19).
If the radius in the drawing is less than 6 mm, it is recommended to position the arrow on the outside of the arc. If necessary, specify the position of the center of the arc, it is marked by the intersection of the center or extension lines (Fig. 20).
In those cases when the drawing shows an arc of large radius, for which the center can be omitted, the dimension line is cut off without reaching the center (Fig. 21).
If, in this case, the center must be noted, it is allowed to bring it closer to the arc (Fig. 22).
In this case, the dimension line is shown with a 90 ° kink, and both sections of the dimension line are drawn in parallel. Dimensional lines extending from the same center and intended to indicate dimensional arcs should not be placed on one straight line. Radii are recommended to designate arcs up to 180 °; arcs whose magnitude is more than 180 ° are indicated by diameter.
The sign of the arc "⌒" is applied above the dimension number (Fig. 23). The length of the arc is set in linear units, and the dimension number denoting the arc is plotted above the dimension line in accordance with the usual requirements.
To set the size of the square, use the corresponding "□" sign, whose height is 7/10 of the height of the dimension number (Fig. 24, a). With a different arrangement of the square, the dimensions of its sides are plotted (Fig. 24, b). It should be noted that the sign of the "square" is applied only on the image on which it is projected in a line.
The sign of the conicity of the surface "▷" is applied on the shelf of the leader line located parallel to the axis of the cone or on the axis of the cone (Fig. 25, a). The taper sign is positioned so that its acute angle is directed toward the top of the cone. The value of the taper is determined by the ratio of the difference between the diameters of the two cross sections of the cone to the distance between these sections, i.e. K \u003d (D - d) / lwhere D - diameter of a large section; d - diameter of a smaller section; l - distance between sections. The taper is indicated in the form of a simple fractional number (Fig. 25, b).
The slope mark of the straight line "∠" is indicated on the ledge shelf. Slope i represents the tangent of the angle between a given line and a horizontal or vertical line (Fig. 26, a). The sign of the slope is located so that its acute angle is directed towards the slope of the straight line (Fig. 26, b). The slope, as well as the taper, in the drawing is set with a simple fraction, in percent or in ppm.
To indicate the sphere in the drawing, the sign of "diameter" or "radius" is used. In cases where the sphere is difficult to distinguish from other surfaces in the drawing, the word "Sphere" or the sign "Ο" may be added before the sign of "radius" or "diameter". The inscription on the drawing is carried out according to the type "Sphere Ø17" or "Ο R10" (Fig. 27).
Simple flat parts are depicted as a single projection. In these cases, its thickness is indicated by the lowercase letter s and the inscription on the drawing is of the type "s2" and is located on the shelf of the leader line (Fig. 28, a). The length of the item is indicated by the letter L (Fig. 28, b).
The chamfers in the drawings are applied with two linear dimensions (Fig. 29, a) or one linear and one angular (Fig. 29, b). In case the inclination angle of the generatrix of the cone is 45 °, a simplified designation of the chamfer is used when the dimension line is drawn parallel to the axis of the cone, and the inscription is performed according to the type "2 x 45 °" (Fig. 29, c).
In cases where it is required to indicate the size of the diameter, use the sign in the form of a circle with a line "Ø". This symbol is applied before the dimension number.
Examples of using the diameter sign:
Signs of the diameter on the details of rotation of a cylindrical and conical shape
Dimensions applied with insufficient space
on the dimension line
Designation of sizes with a lack of space
for arrows
Diameter - This is the length of the straight line connecting the circumference of the circle. A piece of diameter, in any case, passes only through the center of the circle. They usually designate it with the Latin letter "D" or the sign "Ø". If the radius of the circle is multiplied by two, the sum will be the diameter. All volumetric bodies having a spherical shape, as well as those at least one of the possible cross-sections of which is a circle, are indicated by diameter symbols. The word " diameter"Came from the Greek word" diametros"- the diameter.
Four hole designation example
with diameter
In the technical drawings, diameters are indicated by the crossed-out “Ø” symbol. This sign is placed in front of the dimensional numbers of parts, which can be either cylindrical or conical.
In cross section, the cone is a right-angled triangle, one of whose legs is parallel to or pines of the body of revolution. Its parameters have the following notation: “D” is the larger diameter, “d” is the smaller diameter, “L” is the length. In the drawing, the diameters of the cone are indicated by numbers in front of which are placed the signs “Ø” and the numerical value is long without lettering.
The most common parts with cylindrical surfaces include shafts for various purposes. Cylindrical bodies formed by the rotation of a rectangle near one of its sides are indicated by a diameter. Smooth shafts have some design features, and are divided into varieties: straight, stepped unilateral, stepped bilateral and heavy. For example, shafts of induction motors, in which the rotor is mated to the shaft by pressing on its largest diameter, and on both sides there are steps for bearings, fans, and pulleys. Bilateral stepped shafts can also be found in various mechanisms where any other design features are required. Cylindrical parts, as a rule, have a total maximum length and outer diameter. Depending on the specific configuration of a particular product, its composition may include such elements as internal and external grooves, steps, undercuts, etc. with different diameters whose values \u200b\u200bare preceded by the signs “Ø”.
Diameter Sign Example
on a spherical surface
Parts with tapered surfaces include instrumental adapter sleeves in which the outer and inner surfaces are tapered. Such bushings provide high centering accuracy and speed of tool change with sufficient rigidity when used on machines. Reducers are short and long.
Conical tool parts of this type are called " morse cone"And are divided into numbers. The angles, lengths and diameters of the adapter sleeves can be taken from special tables. The tabular data uses letter designations such as - “d” is the smaller diameter, “D” is the larger diameter, “L” is the length of the part. In the drawings, diameters and lengths are indicated by digital values, with a “Ø” sign placed in front of the diameter numbers.
« Morse cone"- in addition to adapter sleeves, it is also used in the manufacture of shanks for twist drills, end mills, tools and mandrels. Tool cones are fixed due to elastic and plastic deformation. To implement such connections in the spindles of milling and turning machines, tapered holes are provided for installing an auxiliary tool. In addition, the lathe tailstock tailstock has the same tapered bore.
The technology uses a large number of parts and their elements to indicate which diameter sign is used. For standard diameters, a parametric series is used, which includes standard sizes. When developing technical products, design diameters are rounded to the nearest values. When marked on the technical drawings, the sign of the diameter should be accompanied by a dashed-dotted line indicating the axis, which indicates a round section of the part.
The construction of drawings is not an easy task, but without it in the modern world it is impossible. Indeed, in order to make even the most ordinary item (a tiny bolt or nut, a shelf for books, the design of a new dress and the like), you must initially perform the appropriate calculations and draw a drawing of the future product. However, often it is one person, and another is engaged in the manufacture of something according to this scheme.
In order to avoid confusion in the understanding of the depicted object and its parameters, symbols of length, width, height and other quantities used in the design are adopted throughout the world. What are they? Let's find out.
Quantities
Area, height and other designations of a similar nature are not only physical, but also mathematical quantities.
Their single letter designation (used by all countries) was established in the middle of the 20th century by the International System of Units (SI) and is still used today. It is for this reason that all such parameters are denoted by Latin, and not Cyrillic letters or Arabic script. In order not to create separate difficulties, when developing standards for design documentation in most modern countries, it was decided to use almost the same conventions that are used in physics or geometry.
Any graduate of the school remembers that depending on whether a two-dimensional or three-dimensional figure (product) is depicted in the drawing, it has a set of basic parameters. If there are two dimensions - this is the width and length, if there are three of them - then the height is also added.
So, for starters, let's find out how to correctly designate the length, width, height in the drawings.
Width
As mentioned above, in mathematics, the considered value is one of the three spatial measurements of any object, provided that its measurements are made in the transverse direction. So what is the breadth famous for? Designation with the letter "B" it has. This is known all over the world. Moreover, according to GOST, the use of both capital and lowercase Latin letters is permissible. Often the question arises as to why such a letter is chosen. After all, usually the reduction is made according to the first Greek or English name of the quantity. The width in English will look like "width".
Probably, the point here is that this parameter was most widely used initially in geometry. In this science, describing the figures, often the length, width, height are denoted by the letters "a", "b", "c". According to this tradition, when choosing the letter “B” (or “b”) was borrowed by the SI system (although other two geometric symbols were used for the other two dimensions).
Most believe that this was done so as not to confuse the width (the designation with the letter "B" / "b") with the weight. The fact is that the latter is sometimes referred to as “W” (short for the English name weight), although the use of other characters (“G” and “P”) is also permissible. According to international standards of the SI system, the width is measured in meters or their multiple (fractional) units. It is worth noting that in geometry it is sometimes also acceptable to use “w” to denote widths, but in physics and other exact sciences such a notation is usually not used.
Length
As already indicated, in mathematics, length, height, width are three spatial dimensions. Moreover, if the width is a linear dimension in the transverse direction, then the length is in the longitudinal. Considering it as a quantity of physics, we can understand that this word means a numerical characteristic of the length of lines.
In English, this term is called length. It is because of this that this value is indicated by the capital or lower case initial letter of the word - “L”. Like width, length is measured in meters or their multiple (fractional) units.
Height
The presence of this quantity indicates that we have to deal with a more complex - three-dimensional space. Unlike length and width, height numerically characterizes the size of an object in the vertical direction.
In English, it is written as "height". Therefore, according to international standards, it is denoted by the Latin letter “H” / “h”. In addition to height, sometimes this letter appears in the drawings as a designation as depth. Height, width and length - all of these parameters are measured in meters and their multiple and fractional units (kilometers, centimeters, millimeters, etc.).
Radius and diameter
In addition to the parameters considered, when drawing up drawings, one has to deal with others.
For example, when working with circles, it becomes necessary to determine their radius. This is the name of the segment that connects the two points. The first of these is the center. The second is located directly on the circle itself. In Latin, this word looks like "radius". Hence the lowercase or capital “R” / “r”.
Drawing a circle, in addition to the radius, one often has to deal with a phenomenon close to it - diameter. It is also a segment connecting two points on a circle. Moreover, he necessarily passes through the center.
Numerically, the diameter is equal to two radii. In English, this word is written like this: "diameter". Hence the abbreviation - large or small Latin letter "D" / "d". Often the diameter in the drawings is indicated by a crossed circle - “Ø”.
Although this is a common abbreviation, it is worth bearing in mind that GOST provides for the use of only the Latin "D" / "d".
Thickness
Most of us remember school math lessons. Even then, teachers said that, with the Latin letter "s" it is customary to denote such a value as area. However, according to generally accepted standards, a completely different parameter is recorded in the drawings in this way - thickness.
Why is that? It is known that in the case of height, width, length, lettering could be explained by their spelling or tradition. That's just the thickness in English looks like "thickness", and in the Latin version - "crassities". It is also unclear why, unlike other quantities, thickness can only be indicated with a lowercase letter. The designation "s" is also used to describe the thickness of pages, walls, edges and so on.
Perimeter and Area
Unlike all the values \u200b\u200blisted above, the word "perimeter" came not from Latin or English, but from Greek. It is formed from "περιμετρέο" ("measure the circumference"). And today this term has retained its meaning (the total length of the borders of the figure). Subsequently, the word fell into the English language ("perimeter") and was fixed in the SI system as an abbreviation with the letter "P".
Area is a quantity showing a quantitative characteristic of a geometric figure that has two dimensions (length and width). Unlike all of the above, it is measured in square meters (as well as in fractional and multiple units). As for the letter designation of the area, it differs in different areas. For example, in mathematics it is a Latin letter “S”, familiar to everyone from childhood. Why so - no information.
Some unknowingly think that this is due to the English spelling of the word "square". However, in it the mathematical area is “area”, and “square” is the area in architectural sense. By the way, it’s worth remembering that “square” is the name of the geometric figure “square”. So you should be careful when studying drawings in English. Due to the translation of "area" in certain disciplines, the letter "A" is used as a designation. In rare cases, “F” is also used, but in physics, this letter means a value called “strength” (“fortis”).
Other common abbreviations
Designations of height, width, length, thickness, radius, diameter are the most used in the preparation of drawings. However, there are other quantities that are also often present in them. For example, the lowercase "t". In physics, this means “temperature”, however, according to GOST of the Unified System for Design Documentation, this letter is a step (coil springs, and the like). However, it is not used when it comes to gears and threads.
The capital and lowercase letter "A" / "a" (according to the same standards) in the drawings is used to indicate not the area, but the center-to-center distance. In addition to various values, in the drawings it is often necessary to designate angles of different sizes. To do this, it is customary to use lowercase letters of the Greek alphabet. The most used are “α”, “β”, “γ” and “δ”. However, it is permissible to use others.
What standard defines the letter designation of length, width, height, area and other quantities?
As already mentioned above, so that there is no misunderstanding when reading the drawing, representatives of different nations adopted common standards for letter designation. In other words, if you are in doubt about the interpretation of a particular abbreviation, take a look at GOSTs. This way you will learn how to correctly indicate height, width, length, diameter, radius, and so on.
In the main menu, on the "Start" button - having opened it, go to the "All Programs" section, to the "Standard" section, and then to the "Utilities" section, where you will find a link with this name. Another way is to press the key combination win + r, in the opened program launch dialog enter charmap and press the Enter key.
Find the diameter icon in the table. Please note that there may be several characters similar in style - at least two (depending on the typeface installed). On the first page you can find two options - select the most suitable and double-click it, and then copy to the clipboard by clicking the "Copy" button.
You can do without a character table if you know the code associated with this character in the encoding table. You can enter the hexadecimal code into Microsoft Office Word, then press the alt + x key combination and the word processor will replace the code with its corresponding icon. The two icons that you found on the first page in the character table correspond to the hexadecimal codes 00D8 and 00F8.
Use mnemonic character codes to insert diameter icons in html pages. For example, if you put the sequence of characters ∅ or ∅ in the document code, then for the visitor to the page the result will look like this: ∅. The character primitive ⊕ or ⊕ looks like this: ⊕, ⊗ or ⊗ - ⊗, Ø or Ø - Ø, ø or ø - ø.
A circle is a geometric figure on a plane, which consists of all points of this plane located at the same distance from a given point. The given point in this case is called the center of the circle, and the distance at which the points of the circle are from its center is called the radius of the circle. The area of \u200b\u200bthe plane bounded by a circle is called a circle. There are several methods for calculating the diameter of a circle, the choice of a specific envy of the available initial data.
Instruction manual
In the simplest case, if the circle is of radius R, then it will be equal to
D \u003d 2 * R
If the radius of the circle is not known, but its is known, then the diameter can be calculated by the length formula circles
D \u003d L / P, where L is the circumference, P - P.
Also, the diameter of the circle can be calculated, knowing the area it is limited
D \u003d 2 * v (S / P), where S is the area of \u200b\u200bthe circle, P is the number P.
In special cases, the radius of a circle is possible if it is described or inscribed in a triangle.
If the circle is inscribed in a triangle, then its radius is found by the formula
R \u003d S / p, where S is the area of \u200b\u200bthe triangle, p \u003d (a + b + c) / 2 is the semiperimeter of the triangle.
For a circle described near a triangle, the radius formula has the form
R \u003d (a * b * c) / 4 * S, where S is the area of \u200b\u200bthe triangle.
Sources:
- circle diameter calculation
The sign of the diameter is found in the drawings and accompanying documents with him. It is not available in all code tables, but is completely absent on the keyboard. This sign has to be entered in an indirect way.
Instruction manual
In case the diameter of the metric thread is indicated, a special sign is not required. Use the capital letter M instead.
Open the symbol table to enter the diameter sign when using the OfficeOffice.org Writer, Abiword, and Microsoft Office Word office suites. To do this, use the menu item called "Insert" - "Special Character" or similar. Find the diameter sign in the table, and if that fails, try to find it in a different font. After that, click on this symbol, and then on the OK button, and it will be inserted.
To enter a diameter sign when typing in the browser input field, as well as when working with HTML in the TXT file editor, run one of the office packages mentioned above, type a diameter sign in it using the symbol table, then select it with the mouse and copy it to clipboard by pressing Ctrl + C, go to the desired place in the edited text, and then paste the character from the clipboard by pressing Ctrl + V. This technique works only if the document is edited in Unicode encoding. Note that the Notepad editor may not support this encoding. Use Geany, Kwrite (on Linux), or Notepad ++ (on Windows) instead.
You can also take the diameter sign directly from this paragraph: ⌀. Select it, copy to the clipboard and paste from the latter into the document, as described above.
In computer-aided design (CAD) systems, a diameter sign is inserted automatically when the measurement and sizing function is used. Through the menu, indicate that this size is the diameter. For example, if the Sudarushka program is used, the corresponding menu item has the following arrangement: “Dimensions” - “Diameter”. For a linear dimension, if it relates to a projection, the diameter sign in this program can be put down like this: “Dimensions” - “Resize” - “Text” - “Size Type”.
When editing a document in eight-bit Cyrillic encoding, inserting a diameter sign is not possible. Use the capital Russian letter “F” instead.
A circle is a closed curve line, all points of which are equally spaced from one point. This point is the center of the circle, and the segment between the point on the curve and its center is called the radius of the circle.