The thread on the rods is depicted along the outer diameter with solid main lines, and along the inner diameter with solid thin lines.
The main elements of metric threads (outer and inner diameters, thread pitch, thread length and angle) you studied in the fifth grade. Some of these elements are shown in the figure, but such inscriptions are not made on the drawings.
The thread in the holes is depicted with solid main lines along the inner diameter of the thread and solid thin lines along the outer one.
The thread symbol is shown in the figure. It should be read like this: metric thread (M) with an outer diameter of 20 mm, the third accuracy class, right, with a large pitch - “M20 thread class. 3".
In the figure, the thread designation “M25X1.5 class. 3 left" should be read as follows: metric thread, thread outer diameter 25 mm, pitch 1.5 mm, fine, third accuracy class, left.
Questions
- What lines represent the thread on the rod?
- Which lines show the threads in the hole?
- How is the thread on the drawings?
- Read the entries “M10X1 class. 3" and "M14X1.5 class. 3 left.
working drawing
Each product - a machine or a mechanism - consists of separate interconnected parts.
Parts are usually made by casting, forging, stamping. In most cases, such parts are machined to machine tools- turning, drilling, milling and others.
Drawings of parts, provided with all the instructions for manufacturing and control, are called working drawings.
The working drawings indicate the shape and dimensions of the part, the material from which it must be made. The drawings indicate the cleanliness of surface treatment, the requirements for manufacturing accuracy are tolerances. Manufacturing methods and technical requirements for the finished part are indicated by an inscription on the drawing.
Surface finish. On the processed surfaces there are always traces of processing, irregularities. These irregularities, or, as they say, surface roughness, depend on the tool being processed.
For example, a surface treated with bastard will be rougher (uneven) than after processing with a personal file. The nature of the roughness also depends on the properties of the material of the product, on the cutting speed and the amount of feed during processing on metal-cutting machines.
To assess the quality of processing, 14 classes of surface cleanliness were established. Classes are indicated in the drawings by one equilateral triangle (∆), next to which the class number is affixed (for example, ∆ 5).
Methods for obtaining surfaces of different purity and their designation in the drawings. The purity of the processing of one part is not the same everywhere; therefore, the drawing indicates where and what processing is required.
The sign from the top of the drawing indicates that for rough surfaces there are no requirements for cleanliness of processing. The sign ∆ 3 in the upper right corner of the drawing, taken in brackets, is put if the same requirements are imposed on the surface treatment of the part. This is a surface with traces of processing with bastard files, peeling cutters, and an abrasive wheel.
Signs ∆ 4 - ∆ 6 - semi-finished surface, with subtle traces of processing with a fine cutter, personal file, grinding wheel, fine sandpaper.
Signs ∆ 7 - ∆ 9 - clean surface, without visible traces of processing. Such processing is achieved by grinding, filing with a velvet file, scraping.
Mark ∆ 10 - a very clean surface, achieved by fine grinding, honing on whetstones, filing with a velvet file with oil and chalk.
Signs ∆ 11 - ∆ 14 - surface cleanliness classes, achieved by special treatments.
The manufacturing methods and technical requirements for the finished part in the drawings are indicated by an inscription (for example, blunt sharp edges, harden, burnish, drill a hole together with another part and other requirements for the product).
Questions
- What are the symbols for surface finish?
- After what type of treatment can a surface finish of ∆ 6 be obtained?
Exercise
Read the drawing in the figure and answer the questions in writing on the proposed form.
| Drawing Reading Questions | Answers |
| 1. What is the name of the part? | – |
| 2. Where is it used? | – |
| 3. List the specifications for the part | – |
| 4. What is the name of the drawing view? | – |
| 5. What conventions are there in the drawing? | – |
| 6. What is the overall shape and size of the part? | – |
| 7. What thread is cut on the rod? | – |
| 8. Specify the elements and dimensions of the part | – |
"Plumbing", I.G. Spiridonov,
G.P. Bufetov, V.G. Kopelevich
A part is a part of a machine made from a single piece of material (for example, a bolt, nut, gear, lead screw lathe). A node is a connection of two or more parts. The product is assembled according to assembly drawings. A drawing of such a product, which includes several nodes, is called an assembly drawing, it consists of drawings of each part or node and depicts assembly unit(drawing of a single ...
It's been discussed a lot here. I will repeat in a general sense why it is necessary to show transition lines conditionally: 1. To make the drawing readable. 2. From the transition lines shown conditionally, you can set dimensions that are often not put down on any other view or section. Here is an example. There is a difference? 1. As it is now possible to display in all the listed CAD systems. And here's how to display it. Transition lines are shown conditionally and sizes are shown that, in other modes of displaying transition lines, simply cannot be put down. Why did the controller require this? Yes, just so that the drawings have a familiar look after many years of work in 2D and are well read, especially by the customer who coordinates them.
That's right :) this is nonsense :) in TF you can do it anyway =) there will be no noticeable difference in speed, you can even then take any copy to repaint, change holes, delete holes, whatever ... and the array will still remain an array - it will be possible to change the number of copies, the direction, etc., to cut the video or believe it? :) That's right, but what is the task? Translate as SW splines by points into a spline by poles or something, if you think about it, this is also some change in the original geometry - there are no comments about this? :) as I understand it, TF only translates 1 to 1, the rest can already be configured in the TF template before export in DWG - see the figure under the spoiler, or scale it as AC, which in principle does not contradict the main methods of working with AutoCAD, but since, in view of the prevalence of AC on early stages the peak of popularity of CAD implementation, then the age generation is even more familiar with it: And if you still get to the bottom of the possibilities of exporting / importing different CAD systems: 1) then how to export only selected lines from a 2D SW drawing to DWG? (from 3D documents more or less SW is adapted, but you still have to small window preview to clean the excess manually). Delete everything that is not needed in advance, and then export-> somehow not modern, not youthful :) 2) And vice versa, how to quickly import selected lines in AutoCAD into SW (for example, for a sketch, or just as a set of lines drawing)? (for TF: selected a set of necessary lines in AC -ctrl + c and then in TF just ctrl + v - that's it)
What detail are we talking about, otherwise this detail may not need to be mirrored, but simply tied differently and it will be just right. A mirror part is the same configuration only created by the machine, you can make the configuration of the part yourself and in some cases it may turn out to be more elegant, it is also easier to edit later.
The dimensions on the working drawings are affixed so that they are convenient to use in the process of manufacturing parts and during their control after manufacturing.
In addition to what is stated in clause 1.7 "Basic information about dimensioning", here are some rules for dimensioning drawings.
When a part has several groups of holes that are close in size, the images of each group of holes must be marked with special signs. As such signs, blackened sectors of circles are used, using a different number and location for each of the groups of holes (Fig. 6.27).
Rice. 6.27.
It is allowed to indicate the dimensions and number of holes of each group not on the image of the part, but on the plate.
For parts that have symmetrically located, identical in configuration and size elements, their dimensions in the drawing are applied once without indicating their number, grouping, as a rule, all dimensions in one place. The exception is the same holes, the number of which is always indicated, and their size is applied only once (Fig. 6.28).
Rice. 6.28.
The detail shown in fig. 6.27, has a series of holes with the same distance between them. In such cases, instead of a dimensional chain repeating the same size several times, it is applied once (see size 23). Then, extension lines are drawn between the centers of the extreme holes of the chain and the size is applied in the form of a product, where the first factor is the number of gaps between the centers of adjacent holes, and the second is the size of this gap (see size 7 × 23 = 161 in Fig. 6.27). This method of dimensioning is recommended for drawings of parts with the same distance between the same elements: holes, cutouts, protrusions, etc.
The position of the centers of holes or other identical elements, unevenly located around the circumference, is determined by the angular dimensions (Fig. 6.28, a). With a uniform distribution of identical elements around the circumference angular dimensions do not apply, but are limited to indicating the number of these elements (Fig. 6.28, b).
Dimensions related to one structural element details (hole, protrusion, groove, etc.) should be applied in one place, grouping them on the image in which this element is depicted most clearly (Fig. 6.29).
Rice. 6.29.
The position of the inclined surface can be set in the drawing by the size of the angle and two (Fig. 6.30, a) or three linear dimensions (Fig. 6.30, b). If the inclined surface does not intersect with another, as in the first two cases, but is mated with a curved surface (see Fig. 6.17), the straight sections of the contour are extended with a thin line until they intersect, and extension lines are drawn from the intersection points for dimensioning.
Rice. 6.30.
a - first case; b - second case
GOST 2.307–68 also established the rules for depicting and drawing hole sizes in views in the absence of cuts (sections) (Fig. 6.31). These rules reduce the number of cuts that reveal the shape of these holes. This is done due to the fact that in the views where the holes are shown by circles, after specifying the diameter of the hole, they put: the size of the depth of the hole (Fig. 6.31, b), the size of the height of the chamfer and the angle (Fig. 6.31, c), the size of the diameter of the chamfer and the angle (Fig. 6.31, d), the size of the diameter and depth of the counterboring (Fig. 6.31E). If after specifying the diameter of the hole there are no additional instructions, then the hole is considered through (Fig. 6.31, a).
Rice. 6.31.
When sizing, the methods of measuring parts and features are taken into account. technological process their manufacture.
For example, it is convenient to measure the depth of an open keyway on the outer cylindrical surface from the end, so the dimension given in fig. 6.32 a.
Rice. 6.32.
a - open; b- closed
The same size of a closed slot is easier to check if the size shown in fig. 6.32 b. The depth of the keyway on the inner cylindrical surface is conveniently controlled by the size indicated in Fig. 6.33.
Rice. 6.33.
Dimensions must be affixed so that during the manufacture of the part it is not necessary to find out anything by calculations. Therefore, the size marked on the section along the width of the flat (Fig. 6.34) should be considered unsuccessful. The dimension defining the flat is correctly shown on the right side of fig. 6.34.
Rice. 6.34.
On fig. 6.35 shows examples of dimensioning by chain, coordinate and combined methods. With the chain method, dimensions are located on a chain of dimension lines, as shown in fig. 6.35, a. When setting the overall (overall) size, the circuit is considered closed. A closed dimensional chain is allowed if one of its dimensions is a reference, for example, overall (Fig. 6.35, a) or included in the chain (Fig. 6.35, b).
Reference dimensions are those that are not subject to execution according to this drawing and are indicated for greater ease of use of the drawing. Reference dimensions in the drawing are marked with an asterisk, which is applied to the right of the dimension number. AT technical requirements repeat this sign and write: Size for reference(Fig. 6.35, a, b).
To the reference size included in the closed circuit, no limit deviations are affixed. The most common are open circuits. In such cases, one size, at which the smallest accuracy is permissible, is excluded from the dimensional chain or the overall dimension is not affixed.
Dimensioning according to the coordinate method is carried out from a pre-selected base. For example, in fig. 6.35, in this base is the right end of the roller.
The most frequently used combined method dimensioning, which is a combination of chain and coordinate methods (Fig. 6.35, G).
Rice. 6.35.
a, b - chain; in- coordinate; G- combined
On the working drawings of machined parts, in which sharp edges or ribs must be rounded, indicate the value of the rounding radius (usually in the technical requirements), for example: Corner radii 4 mm or Radii not specified 8 mm.
The dimensions that determine the position of the keyways are also affixed taking into account the technological process. On the image of the groove for the segment key (Fig. 6.36, a) the size is taken to the center of the disk cutter, with which the keyway will be milled, and the position of the groove for the parallel key is set to the size to its edge (Fig. 6.36, b), since this groove is cut with a finger cutter.
Rice. 6.36.
a - for segment key; 6 – for prismatic
Some part features are shape dependent cutting tool. For example, the bottom of a blind cylindrical hole turns out to be conical, because the cutting end of the drill has a conical shape. The size of the depth of such holes, with rare exceptions, is affixed along the cylindrical part (Fig. 6.37).
Rice. 6.37.
In the drawings of parts with cavities, the internal dimensions related to the length (or height) of the part are applied separately from the external ones. For example, in the body drawing, a group of dimensions that defines the outer surfaces is placed above the image, and the inner surfaces of the part are determined by another group of dimensions located below the image (Fig. 6.38).
Rice. 6.38.
When only part of the surfaces of the part is to be machined, and the rest must be "black", i.e. such as they turned out during casting, forging, stamping, etc., the dimensions are affixed according to a special rule, also established by GOST 2.307-2011. A group of dimensions related to machined surfaces (i.e., formed with the removal of a layer of material) must be associated with a group of dimensions of "black" surfaces (i.e., formed without removing a layer of material) by no more than one dimension in each coordinate direction.
The housing has only two surfaces that need to be machined. Dimension linking groups of outer and internal dimensions, marked on the hull drawing with the letter A.
If the dimensions of the body cavity were marked from the plane of the left end of the part, during its processing it would be necessary to withstand limit deviations several sizes at once, which is almost impossible.
It's been discussed a lot here. I will repeat in a general sense why it is necessary to show transition lines conditionally: 1. To make the drawing readable. 2. From the transition lines shown conditionally, you can set dimensions that are often not put down on any other view or section. Here is an example. There is a difference? 1. As it is now possible to display in all the listed CAD systems. And here's how to display it. Transition lines are shown conditionally and sizes are shown that, in other modes of displaying transition lines, simply cannot be put down. Why did the controller require this? Yes, just so that the drawings have a familiar look after many years of work in 2D and are well read, especially by the customer who coordinates them.
That's right :) this is nonsense :) in TF you can do it anyway =) there will be no noticeable difference in speed, you can even then take any copy to repaint, change holes, delete holes, whatever ... and the array will still remain an array - it will be possible to change the number of copies, the direction, etc., to cut the video or believe it? :) That's right, but what is the task? Translate as SW splines by points into a spline by poles or something, if you think about it, this is also some change in the original geometry - there are no comments about this? :) as I understand it, TF only translates 1 to 1, the rest can already be configured in the TF template before export in DWG - see the figure under the spoiler, or scale it in the form of AC, which in principle does not contradict the main methods of working with AutoCAD, and since, in view of the prevalence of AS in the early stages of the peak of the popularity of CAD implementation, it is even more familiar to the age generation: And if to get to the bottom of the possibilities of exporting / importing different CAD systems: 1) how to export only selected lines from a 2D SW drawing to DWG? (from 3D documents more or less SW is adapted, but you still have to manually clean the excess in a small preview window). Delete everything that is not needed in advance, and then export-> somehow not modern, not youthful :) 2) And vice versa, how to quickly import selected lines in AutoCAD into SW (for example, for a sketch, or just as a set of lines drawing)? (for TF: selected a set of necessary lines in AC -ctrl + c and then in TF just ctrl + v - that's it)
What detail are we talking about, otherwise this detail may not need to be mirrored, but simply tied differently and it will be just right. A mirror part is the same configuration only created by the machine, you can make the configuration of the part yourself and in some cases it may turn out to be more elegant, it is also easier to edit later.
When the image of the thread on the rod n in the front and left view, the outer diameter of the thread is shown with a solid main line, and the inner one with a solid thin line (Fig. 1.6, a). In the left view, the chamfer is not depicted in order to be able to draw the internal diameter of the thread with a solid thin line, open by one quarter of the diameter of the circle. Please note that one end of the circular arc is not brought to the center line by approximately 2 mm, and its other end intersects the second center line by the same amount. The end of the sliced portion is shown as a solid main line.
At and image of a thread in a hole in the front view, the outer and inner diameters of the thread are shown with dashed lines (Fig. 1.6, b). In the left view, the chamfer is not shown, and the outer diameter of the thread is drawn as a solid thin line, open by one quarter of the circle. In this case, one end of the arc is not adjusted, and the other crosses the center line by the same amount. The inner diameter of the thread is drawn with a solid main line. The thread boundary is shown with a dashed line.
On the section, the thread in the hole is shown as follows (Fig. 1.6, c). Outside diameter draw a solid thin line, and the inner one - a solid main line. The thread boundary is shown as a solid main line.
The type of thread is conditionally indicated:
M - metric thread (GOST 9150-81);
G - cylindrical pipe thread (GOST 6357-81);
T g - trapezoidal thread(GOST 9484-81);
S - thrust thread (GOST 10177-82);
Rd - round thread (GOST 13536-68);
R - pipe conical outer (GOST 6211-81);
Rr - internal conical (GOST 6211-81);
Rp - internal cylindrical (GOST 6211-81);
K - conical inch thread(GOST 6111-52).
In the drawings, after designating the type of thread, (for example M), the value of the outer diameter of the thread is written, for example M20, then a fine thread pitch can be indicated, for example M20x1.5. If the thread pitch value is not indicated after the outer diameter value, this means that the thread has a coarse pitch. The thread pitch is selected according to GOST.
When drawing threaded connections, the following simplifications are used:
1. do not depict chamfers on hexagonal and square heads of bolts, screws and nuts, as well as on its core;
2. it is allowed not to show the gap between the shaft of the bolt, screw, stud and the hole in the parts to be joined;
3. when constructing a drawing of bolted, screw, stud joints on the images of the nut and washer, the lines of the invisible contour are not drawn;
4. bolts, nuts, screws, studs and washers in the drawings of bolted, screw and stud joints are shown uncut if the cutting plane is directed along their axis;
5. when drawing a nut and a bolt head, a screw, the side of the hexagon is taken equal to the outer diameter of the thread. Therefore, in the main image, the vertical lines that define the middle face of the nut and bolt head coincide with the lines that outline the bolt shank.
When making drawings detachable connections most common the following errors:
1. the thread on the rod in the blind hole is incorrectly marked;
2. no thread border;
3. the thread on the chamfer is incorrectly depicted;
4. incorrectly labeled pipe thread;
5. the distance between thin and solid lines is not maintained when depicting a thread;
6. Incorrect connection of internal and external threads (connection of the fitting to the pipe).
Bolted connection
Bolt - a threaded fastener in the form of a cylindrical rod with a head, part of which is threaded (Fig. 1.13).
The dimensions and shape of the head allow it to be used for screwing a bolt with a standard wrench. Usually, a conical chamfer is made on the head of the bolt, which smooths out the sharp edges of the head and facilitates the use of a wrench when connecting the bolt to the nut.
Rice. 1.13. Photograph of a hex head bolt with a screwed nut
bonding two or more parts with a bolt, nut and washer is called a bolted connection (Fig. 1.14) .
Bolted connection consists of:
§ connected parts (1, 2);
§ washers (3);
§ nuts (4),
§ bolt (5).
For the passage of the bolt, the parts to be fastened are smooth, i.e. unthreaded, coaxial cylindrical holes of larger diameter than the diameter of the bolt. A washer is put on the end of the bolt protruding from the fastened parts and a nut is screwed on.
The sequence of execution of the drawing of a bolted connection:
1. Depict the parts to be connected.
2. Picture a bolt.
3. Depict the puck.
4. Depict a nut.
For educational purposes, it is customary to draw a bolted connection according to relative dimensions. The relative dimensions of the elements of the bolted connection are determined and correlated with the outer diameter of the thread:
§ diameter of a circle circumscribed around a hexagon D=2d;
§ bolt head height h=0.7d;
§ length of the threaded part lo=2d+6;
§ nut height H=0.8d;
§ bolt hole diameter d=l,ld;
§ washer diameter Dsh=2.2d;
§ washer height S=0.15d.
Exist different types bolts that differ from each other in the shape and size of the head and rod, in the thread pitch, in manufacturing accuracy and in execution.
Bolts with hexagonal heads have from three (Fig. 1.15) to five versions:
§ Execution 1 - without a hole in the rod.
§ Execution 2 - with a hole in the rod for a cotter pin.
§ Execution 3 - with two through holes in the head, intended for cotter pinning with wire in order to prevent self-unscrewing of the bolt.
§ Execution 4 – with round hole at the end of the bolt head.
§ Execution 5 - with a round hole in the end of the bolt head and a hole in the rod.
When depicting a bolt in the drawing, two views are performed (Fig. 1.16) according to general rules and dimension:
Rice. 1.14. Bolted connection
1. length L of the bolt;
2. thread length Lo;
3. turnkey size S ;
4. thread designation Md .
Head height H in bolt length is not included.
The hyperbolas formed by the intersection of the conical chamfer of the bolt head with its faces are replaced by other circles.
A simplified image of a bolted connection is shown in Figure 1.17.
Rice. 1.15. Hex head bolt design
Examples of symbols for bolts:
1. Bolt Ml2 x 60 GOST 7798-70 - with a hexagonal head, the first version, with M12 thread, coarse thread pitch, bolt length 60 mm.
2. Bolt M12 x 1.25 x 60 GOST 7798-70 - with fine metric thread M12x1.25, bolt length 60 mm.
Stud connection
Hairpin - fastener, the rod is threaded at both ends (Fig. 1.18).
Stud connection - connection of parts, carried out with the help of a stud, one end of which is screwed into one of the parts to be connected, and the attached part, a washer and a nut are put on the other (see Fig. 1.19). Used for tightening and fixing on given distance elements metal structures with metric thread.
Rice. 1.20. Simplified image of a hairpin connection
The connection of parts with a stud is used when there is no room for a bolt head or when one of the parts to be connected has a significant thickness. In this case, it is not economically feasible to drill deep hole and install a long bolt. Stud connection reduces the weight of structures.
The design and dimensions of the studs are determined by the standards depending on the length of the threaded end l1 (see Table 1).
The drawing of the pin connection is performed in the following sequence and according to the parameters indicated in fig. 1.19:
1. Depict the part with threaded hole.
2. Depict a hairpin.
3. Draw an image of the second connected part.
4. Depict the puck.
5. Depict a nut
Examples symbol hairpin:
1. Stud M8 x 60 GOST 22038-76 - with a large metric thread with a diameter of 8 mm, the length of the stud is 60 mm, designed for screwing into light alloys, the length of the screwed end is 16 mm;
2. Stud M8 x 1.0 x 60 GOST 22038-76 - the same, but with a fine thread pitch of -1.0 mm.
screw connection
The screw is a threaded rod with a head, the shape and dimensions of which differ from the heads of the bolts. Depending on the shape of the screw head, they can be screwed with keys or screwdrivers, for which a special slot (slot) for a screwdriver is made in the screw head (Fig. 1.21). Screw differs from a bolt in the presence of a slot (slot) for a screwdriver.
Rice. 1.22. screw connection
Screw connection includes parts to be connected and screw with washer. In connections with countersunk screws and set screws, a washer is not used.
By appointment, the screws are divided into:
§ fasteners - are used to connect parts by screwing a screw with a threaded part into one of the connected parts.
§ adjusting - used for mutual fixation of parts.
In the set screws, the rod is cut completely and they have a cylindrical, conical or flat pressure end (Fig. 1.23).
Rice. 1.23. Set screws
Depending on the working conditions, the screws are made (Fig. 1.24):
§ with a cylindrical head (GOST 1491-80),
§ semicircular head (GOST 17473-80),
§ semi countersunk head (GOST 17474-80),
§ countersunk head (GOST 17475-80) with a slot,
§ With a turnkey head and with a corrugation.
In the drawing, the shape of the slotted screw is completely conveyed by one image on a plane parallel to the axis of the screw. At the same time, they indicate:
1. thread size;
2. screw length;
3. length of the cut part (lo = 2d + 6 mm);
4. symbol of the screw according to the relevant standard.
The sequence of execution of the drawing of a screw connection:
1. Depict the parts to be connected. One of them has a threaded hole into which the threaded end of the screw is screwed.
Rice. 1.24. Types of screws
2. On the section, the threaded hole is shown by the partially closed threaded end of the screw shaft. The other part to be joined is shown with a gap existing between the cylindrical hole of the upper part to be joined and the screw.
3. Depict a screw.
Examples of screw symbols:
1. Screw M12x50 GOST 1491-80 - with a cylindrical head, version 1, with an M12 thread with a large pitch, 50 mm long;
2. Screw 2M12x1, 25x50 GOST 17475-80 - countersunk head, version 2, with fine metric thread 12 mm in diameter and 1.25 mm pitch, screw length 50 mm.
Image of nut and washer
screw - fastener with a threaded hole in the center. It is used for screwing onto a bolt or stud until it stops in one of the parts to be joined.
Depending on the name and working conditions, nuts are made hexagonal, round, wing, shaped, etc. Hexagon nuts are most used.
Nuts are made in three versions (Fig. 1.25):
Version 1 - with two conical chamfers;
version 2 - with one conical chamfer;
version 3 - without chamfers, but with a conical protrusion from one end.
The shape of the nut in the drawing is conveyed by two types:
§ on the plane of projections parallel to the axis of the nut, combine half of the view with half of the frontal section;
§ on a plane perpendicular to the axis of the nut, from the side of the chamfer.
The drawing indicates:
§ thread size;
§ the size S Full construction;
§ designation of the nut according to the standard.
 |
Rice. 1.25. Nut shapes
Nut symbol examples:
Nut M12 GOST 5915-70 - the first version, with a thread diameter of 12 mm, coarse thread pitch;
Nut 2M12 x 1.25 GOST 5915-70 - the second version, with a fine metric thread with a diameter of 12 mm and a pitch of 1.25 mm.
A washer is a turned or stamped ring that is placed under a nut, screw or bolt head in threaded connections.
The plane of the washer increases the bearing surface and protects the part from scuffing when tightening the nut with a wrench.
Round washers according to GOST 11371-78 have two versions (Fig. 1.26):
§ version 1 - without chamfer;
§ execution 2 - with bevel.
The shape of a round washer is conveyed by one image on a plane parallel to the axis of the washer.
The inner diameter of the washer is usually 0.5 ... 2.0 mm larger than the diameter of the bolt shaft on which the washer is put on. The symbol of the washer also includes the diameter of the thread of the rod, although the washer itself does not have a thread.
Washer symbol examples:
 |
Rice. 1.26. Washer shapes
Washer 20 GOST 11371-78 - round, first version, for a bolt with M20 thread;
Washer 2.20 GOST 11371-78 - the same washer, but of the second version.
For the purpose of protection threaded connection from spontaneous unscrewing under conditions of vibration and alternating load, apply:
§ spring washers according to GOST 6402-70;
§ locking washers with protrusions-paws.
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