Threaded pin. Screws - GOST, designations Designation of bolts in the specification

Fasteners are used to connect various parts structures. To fasteners (namely, this is often called in everyday life fasteners) include screws, bolts, nuts, self-tapping screws, screws, rivets, studs, pins, washers, dowels, etc.

In engineering, one of the most important and widespread detachable connections is bolted. Its main advantage is that when using it, it is not required to cut threads on those parts that are fastened together. This feature of the bolted connection is especially important when the material from which the parts to be joined are made is not able to provide the required thread strength and durability.

Bolted joints also have their drawbacks. These include, for example, the fact that for its implementation, there must be enough space on the parts to be joined to accommodate the head of the screw or nut. In addition, in the process of screwing or unscrewing the nuts, you need to hold the head of the screw so that turning does not occur. It should also be noted that, compared to, say, a screw connection, a bolted connection leads to greater increase weight of the finished product.

If for some reason it is impossible to establish a bolted connection or it turns out to be irrational, then screws and studs are used. So, for example, they usually do it when it is not possible to provide access to the head (nut) or simply there is no place to place it. Another common case is the significant thickness of the parts, the consequence of which is the need for deep drilling and the use of long bolts.

Washers are used as lining elements. They are installed under the heads of screws or nuts in order to reduce the degree of deformation of parts by clamping elements when they are made of not very durable material(e.g. wood, aluminium, plastic, etc.). In addition, using washers, it is possible to prevent parts from scratching when screwing a screw or nut, as well as to compensate for a significant hole gap. As practice shows, using washers in other cases does not make much sense. If it is necessary to protect the connection from self-unscrewing, then safety or lock washers are also used.

Simplified and conditional images in the drawings of general views and assembly drawings of the image fasteners for all industries and construction are established by such a document as GOST 2.315 - 68.

Selection of a conditional or simplified image of fasteners in drawings general view and assembly drawings is made depending on what is the scale and what is the purpose of each specific technical document. Conditional images are used for those fasteners, the diameters of which, when depicted in the drawings, are 2 millimeters or less. In this case, the rule should be fully respected, according to which the idea of the nature of the connection should be given completely.

The use of conditional and simplified images of fasteners should be carried out in accordance with the tables below.

Simplified and symbolic images of fasteners

Simplified image	Conditional image	Name
		Hex head bolts
		Square head bolts
		Hammer head bolts
		Bolts with round head and mustache

		Swing bolts round head
		Swing bolts with fork
		foundation bolts
		Button head screws
		Pan head screws
		Socket head screws with sphere
		Cross head screws
		Socket Head Screws with Cross Sphere
		Allen screws
		Countersunk Head Screws
		countersunk head screws
		Cross countersunk screws
		Self-tapping screws with a cylindrical head
		Cross countersunk head screws

		Round nuts
		Hex nuts
		Slotted and slotted hexagon nuts
		Wing nuts
		Pan head screws
		Countersunk head screws
		Screws with semi countersunk head
		hairpins
		Simple washers, lock washers, etc.
		Lock washers with tongue
		Spring washers
		Cylindrical pins
		Tapered pins
		Nails
		pins
		Threaded inserts

Examples of simplified and conditional images fasteners in connections

Simplified image	Conditional image

If the objects in the assembly drawings have several similar connections in their design, then the fasteners included in them in one or two places of each of them should be depicted in a simplified or conditional way, and in other places it is enough just to use axial or center lines.

Designation of fasteners in the drawing

In cases where the drawing has a number of fastening groups that differ in size and type, it is better to apply them using conventional signs, indicating the position number only once.

If there are identical fastening groups on the construction drawings, then it is permissible to circle them with a thin solid line, and make an explanatory inscription on the leader shelf. As for the predominant fasteners, they are not outlined and are not specified in the general instructions for the drawing.

Identical fasteners

One solid line is used to represent slots on fastener heads.

Designation of slots in the drawing

In cases where the slot line drawn at an angle of 45 ° to the drawing frame coincides with the center line or is close to it, then it is drawn at an angle of 45 ° to the center line.

Symbol for slots

To connect parts, standard fasteners are used threaded parts: bolts, screws, studs, nuts.

Threaded fasteners are manufactured according to relevant standards and, as a rule, have a metric thread with a large pitch, less often with a fine one.

Each fastener has a symbol, which reflects: accuracy class, shape, main dimensions, materials and coating.

16.1. bolts

The bolt consists of two parts: a head and a threaded shank.

Bolt symbol : Bolt 2 M 16 × 1.5. 6g × 75.68.09 GOST 7798-70-2 – execution; M 16 - type and size of thread; 1.5 - the value of the fine thread pitch; 6g - tolerance field; 75 - bolt length ι ; 68 - conditional record of the strength class, indicating that the bolt is made of steel with certain mechanical properties; 09 - zinc coating; GOST 7798-70 is a standard indicating that the bolt has a hex head and is made with normal accuracy.

Figure 16.1

16.2. nuts

Nuts are screwed onto the threaded end of the bolt, while the parts to be joined are clamped between the nut and the bolt head.

Nut symbol : Nut M 24 -6N. 6 GOST 5915-70 - hex nut, version 1 according to GOST 5915-70 with tolerance field 6N, strength class 6, uncoated. Most often, hex nuts are used, the design and dimensions of which are determined by GOST. They are divided into ordinary (Figure 16.2), slotted (Figure 16.3) and crowned (Figure 16.4).

Ordinary nuts are produced in three versions and three accuracy classes (A, B, C), normal height, low, high, very high (Figure 16.5), with a normal or reduced turnkey size.

Figure 16.2

Figure 16.3 Figure 16.4

Figure 16.5

16. 3 Screws

A screw is a threaded rod, at one end of which there is a head (Figure 16.6). The heads come in different shapes: cylindrical, semicircular, countersunk, etc.

Screws are of two types - fixing and adjusting. Set screws are used to adjust gaps and fix parts during assembly.

Screw symbol : Screw A M 8 - 6 g × 50. 48 GOST R 50404-92 -

A - accuracy class, M8 - thread diameter, 6 g - tolerance field, 50 - length, 48 - strength class.

Figure 16.6

16. 4 Studs

The stud is used in cases where the parts do not have room to accommodate the bolt head, or if one of the parts has a significant greater thickness, then it is uneconomical to use a bolt that is too long (Figure 16.7).

The stud is a cylindrical rod with threads at both ends. With one cut end, the stud is screwed into a threaded hole made in one of the parts. A nut is screwed onto the second threaded end, connecting the parts.

Symbol for stud design 1 : M 24-6g × 80.36 GOST 22032-76 - M 24 - nominal diameter of a metric thread with a large pitch; 6g - tolerance field; 80 - hairpin length l; 36 - strength class.

Figure 16.7

ℓ is the length of the stud, ℓ 0 is the length of the nut end, ℓ 1 is the length of the screwed (landing) end, taking into account the thread run. The screwing depth is selected: ℓ 1 = d - in parts made of steel, bronze, brass, titanium; ℓ 1 \u003d 1.25 and 1.6 - in parts made of malleable and gray cast iron; ℓ 1 \u003d 2d and 2.5d - in parts made of light alloys.

Basic fasteners

Figure 1. Types of fasteners
threaded connections of various designs:
a) bolt, nut and washer; b) screw;
c) stud, nut and washer; d) screw, insert and washer

Fastener materials

According to the standard for fasteners GOST 1759.4-87 “Bolts, screws and studs. Mechanical properties and test methods” (“Bolts, screws and studs. Mechanical properties and test methods”), mechanical characteristics carbon and alloy steels used for the manufacture of bolts, screws and nuts, as well as steel grades must comply with those indicated in table 1.

with coarse thread pitch (version 1):
Bolt M10×60.6g.38×A.88.09. GOST 7795-70;
with fine thread pitch (version 2):
Bolt 2M10×60×1.25.6g.38ХА.88.09.GOCT 7795-70.

Conclusion

For fasteners, GOST 27017-86 establishes terminology for various structural forms. The nomenclature of fasteners established by the standard is mandatory for use in all types of documentation and literature using these standards. However, definitions various kinds fasteners established by GOST, it is allowed to supplement them by introducing derivative features and characteristics of fasteners into them, revealing the meaning of the terms used in them, indicating the objects included in the scope of the concept being defined.

Bibliography

Iosilevich G. B., Stroganov G. B., Sharlovsky Yu. V. Tightening and locking of threaded connections.
Gould D., Mikic M. Contact areas and pressure distribution in bolted joints // Design and technology of mechanical engineering. 1972. No. 3 ... - S. 99.
Retsher F. Machine parts: in 2 volumes .. - M .: Gosmashmetizdat. 1933-1934..

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The scope of bolts is incredibly extensive, and in order to choose them correctly, you should familiarize yourself with their types and designations in accordance with GOST. After reading our article, even a non-technical person will be able to cope with this task.

1

This fastener has found its wide application. It is impossible to imagine an industrial area in which bolts would not be used. Construction, aviation, machine building, shipbuilding, and just life - in all these areas they are indispensable. With their help, you can get a strong, reliable and, which is very convenient, detachable connection. Consists of this fastener from two parts - a rod on which a thread is applied, and a head. It most often has a hexagonal shape.

Hardware is classified depending on the purpose, shape and strength of the product. Let us dwell on the concept of strength class in more detail. This characteristic determines the mechanical properties of the fastener. There are 11 classes in total. They are denoted by two numbers delimited by a dot. The first number multiplied by 100 corresponds to the nominal temporary resistance. For example, for fasteners with an accuracy class of 3.6, it is 300 N / mm 2. And multiplying the next figure by 10, we find out the nominal yield strength. For the above bolt, it will be 60 N / mm 2.

furniture bolt

There are special ones with a strength class of not more than 5.8. They are mainly used in the construction and furniture industries. But share and road fasteners may already have more high class strength - 8.8. The first found their application during installation attachments agricultural machines. largest class strength (up to 12.9) have engineering products, since they are involved in the assembly of critical structures.

The bolts are hinged in shape, manufactured in accordance with GOST 3033–78. Their feature is the head, made in the form of a movable part of the swivel joint. And here top part eye bolt, the features of which can be found in more detail by studying GOST 4751–73, is a ring. These products are especially relevant for the installation of installations, unloading and loading operations, for towing. And all thanks to the unique design. The bolt shaft is screwed into mounting hole, and you can hook a hook on the ring, tie a rope.

Anchor bolts (GOST 24379.1–2012) are indispensable if you need to fix a heavy object on the wall, hang something from the ceiling, or fix a massive structure. This is a spacer element. During its tightening, the nut located at the end of the product is drawn into the body and expands it.

The bolt heads may be different. The most common rightfully can be called a hexagon, which is ideal for a wrench. These products are manufactured in accordance with the requirements specified in GOST 7798.7817-80, 10602-94 and 18125-72. But there are also hardware with semicircular and countersunk heads (GOST 7783-81, 7801-81, 7802-8 and 7785-81, 7786-81, 17673-81). Noteworthy products with a flange. Structurally, they resemble standard parts, only they have an additional flange. It looks like an ordinary nut.

2

The symbol for hardware appeared in the USSR at the beginning of the last century. Absolutely all parameters are indicated in the full designation, starting from the name of the hardware and its strength class and ending with the standard number. It consists of 13 items. The name of the product is indicated first, followed by the accuracy class. The third position is occupied by the performance of the product. Depending on the state standard, it can be in 4 versions. If version 1 is used, then it is not indicated. Products of execution 2 have a hole for a cotter pin at the end of the threaded part, and 3 - a pair of through holes in the head. Hardware version 4 does not have any additional holes.

On the drawings placed in the directories, such parameters as length, diameter of the rod and threads for each type of hardware are marked. Further, the designation specifies the nominal diameter, pitch, direction and tolerance field of the thread. The eighth position is occupied by the length of the product. Behind it is the strength class. Moreover, in this case, the values of the nominal tensile strength and yield strength may not be delimited by a point. The next is an indication of the use of autonomous or calm steel. Next comes the grade of the material. The last two positions are occupied by coverage information and the state standard number.

3

In this paragraph, we will focus on the main ones. If we are talking about hexagon head bolts, then the strength class, the manufacturer's trademark, must be indicated. A special designation is applied to products with a left-hand thread. Marking can be both recessed and convex, and the size of the characters is completely determined by the manufacturer.

Bolt marking

In the case when low-carbon martensitic steels are used for the manufacture of hardware of strength class 10.9, the class is underlined by a straight line. A designation is applied to the end or side surface heads. In the latter case, the marking signs are made predominantly in-depth. True, convex symbols are also allowed, the main thing is that they do not lead the parameters of the product beyond the limits of the norms. Character sizes are determined by the manufacturer.

4

There are very serious requirements for hardware, which can be found in GOST. also in state standards sketches of products are also given. The drawings show not only the design of the bolts, but also the location and marking features. On the surface of the rod elements there should be no traces of corrosion, mechanical damage and stress cracks. It is possible to have stamping cracks with a length of less than 1d, a width and a depth not exceeding 0.04d of a hardware on the heads and ends of the bolt rods. The depth of rolling bubbles should be less than 0.03d.

Bolt types

Products with flaws are also rejected if they go beyond the chamfer at the end of the head or go to the supporting surface. And the defects located on the edges of the hexagon should not lead the circle beyond limit dimensions. The width of the flaws located on the edge of the recess of the hexagonal head cannot exceed 0.06d. And their depth should be less than the height of the recess. The presence of rowan is also allowed. For bolts with a diameter less than M12, the depth of the defect can be no more than 0.25 mm. For hardware of larger diameter, this parameter should not exceed 0.02d. Products with slight burrs on the bearing surface of the head are not rejected.

Finished products are subject to two types of control: visual and metallographic. With the help of the first it is possible to identify most of the defects. In this case, visual control is carried out without the use of any magnifying devices. In the latter case, we are talking about magnetic testing methods or deep etching.

The scope of bolts is incredibly extensive, and in order to choose them correctly, you should familiarize yourself with their types and designations in accordance with GOST. After reading our article, even a non-professional will be able to cope with this task. technical area Human.

1

This fastener has found its wide application. It is impossible to imagine an industrial area in which bolts would not be used. Construction, aviation, machine building, shipbuilding, and just life - in all these areas they are indispensable. With their help, you can get a durable, reliable and, which is very convenient, detachable connection. This fastener consists of two parts - a threaded rod and a head. It most often has a hexagonal shape.

Hardware is classified depending on the purpose, shape and strength of the product. Let us dwell on the concept of strength class in more detail. This feature defines mechanical properties fasteners. There are 11 classes in total. They are denoted by two numbers delimited by a dot. The first number multiplied by 100 corresponds to the nominal temporary resistance. For example, for fasteners with an accuracy class of 3.6, it is 300 N / mm 2. And multiplying the next figure by 10, we find out the nominal yield strength. For the above bolt, it will be 60 N / mm 2.

furniture bolt

There are special ones with a strength class of not more than 5.8. They are mainly used in the construction and furniture industries. But plow and road fasteners can already have a higher strength class - 8.8. The first found their application in the installation of attachments for agricultural machines. Engineering products have the highest strength class (up to 12.9), since they are involved in the assembly of critical structures.

The bolts are hinged in shape, manufactured in accordance with GOST 3033–78. Their feature is the head, made in the form of a movable part of the swivel joint. But the upper part of the eyebolt, the features of which can be found in more detail by studying GOST 4751–73, is a ring. These products are especially relevant for the installation of installations, unloading and loading operations, for towing. And all thanks to the unique design. The bolt shaft is screwed into the mounting hole, and a hook can be hooked onto the ring and a rope can be tied.

Anchor bolts (GOST 24379.1–2012) are indispensable if you need to fix a heavy object on the wall, hang something from the ceiling, or fix a massive structure. This is a spacer element. During its tightening, the nut located at the end of the product is drawn into the body and expands it.

The bolt heads may be different. The most common rightfully can be called hexagonal, which is ideal for wrench. These products are manufactured in accordance with the requirements specified in GOST 7798.7817-80, 10602-94 and 18125-72. But there are also hardware with semicircular and countersunk heads(GOST 7783-81, 7801-81, 7802-8 and 7785-81, 7786-81, 17673-81). Noteworthy products with a flange. Structurally, they resemble standard parts, only they have an additional flange. It looks like an ordinary nut.

2

3

Bolt marking

In the case when low-carbon martensitic steels are used for the manufacture of hardware of strength class 10.9, the class is underlined by a straight line. A designation is applied to the end or side surface of the head. In the latter case, the marking signs are made predominantly in-depth. True, convex symbols are also allowed, the main thing is that they do not lead the parameters of the product beyond the limits of the norms. Character sizes are determined by the manufacturer.

4

There are very serious requirements for hardware, which can be found in GOST. Also in the state standards are given and sketches of products. The drawings show not only the design of the bolts, but also the location and marking features. On the surface of the rod elements there should be no traces of corrosion, mechanical damage and stress cracks. It is possible to have stamping cracks with a length of less than 1d, a width and a depth not exceeding 0.04d of a hardware on the heads and ends of the bolt rods. The depth of rolling bubbles should be less than 0.03d.

Bolt types

Products with flaws are also rejected if they go beyond the chamfer at the end of the head or go to the supporting surface. And the defects located on the edges of the hexagon should not take the circle beyond the limiting dimensions. The width of the flaws located on the edge of the recess of the hexagonal head cannot exceed 0.06d. And their depth should be less than the height of the recess. The presence of rowan is also allowed. For bolts with a diameter less than M12, the depth of the defect can be no more than 0.25 mm. For hardware of larger diameter, this parameter should not exceed 0.02d. Products with slight burrs on the bearing surface of the head are not rejected.

When preparing technical design documentation (including such as working and assembly drawings), developers need to name its contents in some way. For this, words are used that reflect the meaning of these entities.

When working drawings are drawn up, a word such as “ hairpin". In technology, it means a rod used as fastener threaded at both ends.

One of its parts with carvings, hairpin is screwed into the main part, and the other passes with a gap through the hole of the part that is supposed to be fixed, and its fixation is carried out by screwing the nut onto the second threaded part hairpins. There is another mounting option: it is threaded into the holes of the two fastened parts hairpin, and nuts are screwed onto its ends.

It should be noted that the scope of such fasteners as studs is practically unlimited. They are widely used in mechanical engineering, instrument making, many other industries, construction. Studs are used during assembly modern engines internal combustion, other vehicle components, during the installation of ventilation systems, heating systems, water supply and gas supply. Installation of billboards, fixing boards and timber during installation is not complete without studs wooden buildings and many other processes.

Fasteners and connection types

The most common and most widely used threaded parts are screws, bolts, nuts, studs and inserts. It is with their help that the largest number various connectors.

Which type of connection to use in each particular case is determined by factors such as:

The strength of the material from which the parts are made;

Features of their design and manufacturing technology;

The frequency with which assembly and disassembly of the connection will be carried out during operation.

Bolted connections are used only in cases where there is sufficient free access to both the bolt head and the nut. In addition, it makes sense to use them in order to fasten together parts that have a relatively small thickness, also when the assembly and disassembly of the connections will be carried out repeatedly. In the last of the listed cases, it also makes sense to give preference to connecting with screws or studs (especially in cases where the thickness of the parts to be joined is really large).

In cases where access mounting tool is provided only on one side (for example, only to the nut), it is most preferable to use screws and studs to fasten the parts together. It should be noted that if the connection will experience significant loads, then screws should not be used, but it is better to use studs instead. Their fixation (locking) is carried out directly in the body parts. It is necessary in order to prevent them from unscrewing when it is necessary to unscrew the nuts. Locking is carried out with the help of adhesives, screwing on the thread run, landing on the thread with an interference fit.

The main materials that should be used in the manufacture of studs, nuts, bolts and screws, as well as their mechanical parameters, are specified in GOST 1759–82. According to this document, 12 strength classes are provided for studs, screws and bolts manufactured from alloyed and carbon steels, and seven for nuts. As for the choice of material for the production of a particular product, it is determined by the working conditions and manufacturing technology.

For mass production of bolts, steel grades 16XSN, 15X, 15, 10 are used, cold heading technology is used. The thread on such bolts is rolled. They are protected from corrosion by applying oxide films or galvanic coatings.

Test 15.03.02

II semester.

exercise 1.

Stud connection

Sheet layout

Drawing progress

l is the length of the hairpin.

b is the thickness of the part;

h - nut height h = 0.8 d;

n is the height of the washer n = 0.15d.

R = 1.5d, r - by construction.

Note:

Literature

Table 1

Studs for parts with threaded holes are shown

In GOST 22032-76 GOST 22043-76

Range of stud lengths: 16, (18), 20, (22), 25, (28), 30,(32), 35, (38), 40, (42), 45, (48), 50, 55, 60, 65, 70, 75, 80, (85), 90, (95), 100, (105), 110, (115), 120, 130, 140, 150.

Rated thread diameter
thread pitch	large	1,5	1,75			2,5		3,5
small	1,25	1,25	1,5	1,5	1,5
Attitude	;	;	;	;	;		;
;	;	;	;	;	;	;	;
;	;	;
;

Notes: 1. Metric thread according to GOST 9150-81.

2. Thread tolerances according to GOST 16093-70.

3. Thread run according to GOST 10549-63.

4. Technical requirements according to GOST 1759-70.

table 2

WASHERS according to GOST 11371-78

	Fastener shaft diameter d 1
d w	10,5
D w
H w		2,5	2,5
With	0,5	0,6	0,6	0,8	0,8	1,0	1,0	1,25

Technical requirements GOST 18123-70

Table 3

Table 5

Task 2.

Bugulma branch

Department of Mathematics and

applied mechanics

Sketchbook

Subject: Assembly drawing

Performed by student gr. 08 .I. Petrov

Checked by T.A. Mutugullina

2. Drawing up and registration of working drawings of parts

Detail drawing contains an image of the part and other data necessary for its manufacture and control (dimensions, tolerances, material, surface finish, etc.). A drawing, unlike a sketch, is performed using drawing tools, in compliance with the scale on standard formats (Fig. 3 and 4).

For making working drawings of parts, a scale of 1:1 is preferable. An exception is made for relatively small or large details, which are respectively drawn on an enlargement or reduction scale.

The drawings are drawn up in compliance with the requirements of the ESKD standards, which determine the formats, scales, lines, fonts and formulate the rules for performing images and sizing.

Terms educational process part of the information about the part on the training drawings can be omitted (for example, tolerances and fits, instructions for heat treatment, etc.)

When performing a working drawing from nature, part defects (casting inaccuracy, shells, wear, etc.) are not reflected.

Detail - a product made from a homogeneous material. It cannot be disassembled into smaller elements (GOST 2.101-68).

assembly unit- a product, the components of which are connected using assembly operations (screwing, welding, riveting, etc.). Assembly units include valves used to completely or partially block pipeline passages in the heating system, water supply and gas pipelines. Depending on the nature of the movement of the shutter, taps and valves are distinguished.

AT cranes the passage is blocked by a plug that rotates around its axis. The presence of a gap between the lower end of the plug and the bottom of the housing allows long time maintain a tight fit of the cork during natural wear of rubbing surfaces. In the drawings, the valves are shown in the open position.

AT valves the passage is blocked by a spool that reciprocates around the axis of the passage. In the drawing, the valves are shown in the closed position.

3. Drawing up and registration of assembly drawings

Assembly drawing - a drawing containing an image of an assembly unit and other data necessary for its assembly, processing in assembled and control. The assembly drawing should give an idea of the design, principle of operation, location and interconnection constituent parts products.

Assembly drawings are made in the following sequence:

1. Held preparatory work which includes:

Establishment of the name, purpose and principle of operation of the product;

Determination of the component parts of the product and methods of their connection (threading, welding, soldering, etc.);

Preparation of a diagram of the relative position and connection of the component parts of the product (parts);

Drawing up a specification;

Making sketches of parts;

Selecting the main image;

Determining the number and content of the required images (views, cuts, sections);

Define the drawing scale and sheet format.

2. A frame, main and additional inscriptions are drawn on the selected standard sheet format, after which the layout of the drawing is carried out ( mutual arrangement images on the drawing).

3.Conducted centerlines images.

4. Images are drawn sequentially in thin lines, starting from the main one. First, the main part is depicted, then it is gradually filled with the rest of the details.

On the assembly drawing, it is conditionally allowed not to show gaps, chamfers, roundings, grooves, protrusions and other small elements.

5. Necessary cuts and sections are made.

6. The overall (length, width, height of the product), installation (used in the installation of the product) and connecting dimensions (dimensions of the elements of the product for attaching parts of other products) are indicated.

7. Hatching is applied on cuts and sections. Adjacent parts are hatched in different sides, or with a different step, or with a shift of some lines relative to others. For the same detail on all images of the drawing, the slope and hatching step are preserved.

8. All parts are numbered in accordance with the position numbers specified in the specification of the assembly unit. Position numbers are indicated on the shelves of leader lines. Shelves are located outside the outline of the image parallel to the main inscription of the drawing in a horizontal line or vertical column. It is allowed for a group of fasteners (washers, nuts, etc.) related to one attachment point to draw one common leader line with a vertical arrangement of position numbers (Fig. 6). The font size of the position numbers should be one or two sizes larger than the font size of the dimension numbers. Leader lines end with dots, and in the case when the part is small, with an arrow.

Drawing up a specification

Specification - text design document that defines the composition of the assembly unit. It is performed on separate sheets of A4 format (GOST 2.108-68) in the form shown in fig. one.

The specification consists of sections arranged in the following order: assembly units, parts, standard products, materials. The title of each section is indicated as a heading in the column "Name" and underlined. A few free lines are left between sections so that, if necessary, the table can be supplemented with new position numbers. If the section is empty, then it is omitted from the specification.

The designation of the assembly drawing ends with the letters "SB.". And this designation is indicated in the main inscription of the assembly drawing.

In the "Details" section, in order of decreasing complexity, non-standard parts are listed, in the designation of which the last digit corresponding to the position number is changed

For parts that do not have a working drawing, in the column "Format" it is written "BC" (without a drawing), and in the column "Name" the material is indicated: from which the part is made.

In the "Standard products" section, the names are recorded by product groups in alphabetical order (nut, washer, etc.) and in ascending standards.

For example: Nut MP.5.019 GOST 5918-73

Nut M8.5.029 GOST 5927-70.

Details of one standard are arranged in ascending order of their main parameters or sizes.

For example: Bolt M5x10.109 GOST 7798-70

Bolt М10хЗ0.109 GOST 7798-70

If the parts differ only in size, the following recording option is allowed:

Nuts GOST 5915-70

The column "Designation" for standard products remains empty.

The title block of the specification is different from the title block of the drawing. The dimensions and shapes of the main inscription of the specification are shown in fig. 7

Task 3.

Detailing

Exercise. Make working drawings of three parts circled in the drawing by options.

Assembly drawings intended for educational purposes have some features and deviations from the requirements unified system design documentation (ESKD).

When making drawings of parts, students should be able to apply the knowledge that they received in the classes in engineering graphics. For example, when reading an assembly drawing, one should know GOST 2.109-73 well for simplifications and conventions. The assembly drawing is performed, as a rule, with simplifications. On assembly drawings, it is allowed not to show chamfers, fillets, grooves, recesses, protrusions, fillets, gaps between the rod and the hole.

To perform the detailing of the assembly drawing, you must:

1. Carefully understand the assembly drawing. At the same time, reading the drawing should begin with the main inscription and specification, i.e., first you need to familiarize yourself with the name, quantity and material of the parts, then find each part in positions on all images of the assembly drawing, trying to present in in general terms her form.

2. Familiarize yourself with the device and the interaction of the parts of the assembly unit.

3. Pay attention to the ways of connecting individual parts to each other.

4. Identify the required (smallest) number of views for the image of each detail, so that these views can be used to determine the shape and size of the details.

5. Select a scale for each detail drawing in accordance with GOST 2.302-68.

6. The dimensions of parts during training detailing should be determined according to the assembly drawing with a measuring instrument and a ruler, taking into account the scale indicated in the main inscription of the assembly drawing.

On the completed drawings of parts, apply the designations of surface roughness and all dimensions.

When applying dimensions, it is necessary to know in which cases the dimensions of the radii are indicated and in which dimensions of the diameters.

During training detailing, the dimensions of the thread of the part are determined by the outer diameter of the thread taken from the assembly drawing and rounded to the nearest standard size according to GOST. The thread is mostly metric everywhere with a small or large pitch (the thread pitch is determined by the student tentatively with the help of a teacher).

On training drawings metric thread is indicated in a simplified way, i.e., without indicating deviations.

The dimensions of a non-standard rectangular thread can be selected approximately according to the table. 1 (Fig. 2), intended for educational purposes only.

Table 1.

d	d1	P	n	d	d1	P	n

Dimensions, mm

Test work 15.03.02

II semester.

1. Threaded connections(Stud connection). Making a drawing of a stud, a stud socket and a stud connection in 2 images.

2. Assembly drawing. Making sketches of parts included in the assembly unit. Execution of assembly drawing. Specification.

3. Detailing. Making working drawings of three parts and a perspective view of one of them.

Only 4 ÷ 5 A3 format and an album of sketches.

exercise 1.

Stud connection

On A3 format, make a working drawing of a stud, a socket for a stud and a connection with a stud in 2 images according to an individual task. Apply the dimensions indicated by the * sign and the symbols of the nuts, studs, washers.

Sheet layout

Drawing progress

1. Draw a working drawing of a stud in one image (view):

d – nominal thread diameter (for MIO=10 mm);

d in - inner diameter of the thread (see table 3);

d 1 - the diameter of the smooth part of the stud is taken equal to d;

l is the length of the hairpin.

l calc. = b + K + h + n » b + 1.3d, where

b is the thickness of the part;

K – protruding above the nut part of the stud rod K = 0.3 ... 0.5 d;

h - nut height h = 0.8 d;

n is the height of the washer n = 0.15d.

l calc. round up to a larger standard size l (see Table 1). Knowing l, determine l 0 (Table 1).

Thread run (see Table 4). The length of the smooth part of the stud with the thread run of the nut end must be at least 0.5 d. The length of the screwed end of the stud l 1:

In steel, bronze, brass parts and parts made of titanium alloys l 1 = 1d (GOST 22032-76);

In parts made of malleable and gray cast iron, and also allowed in steel and bronze parts l 1 = 1.25d (GOST 22034-76), l 1 = 1.6d (GOST 22036-76);

In parts made of light alloys l 1 = 2d (GOST 22038-76), l 1 = 2.5d (GOST 22040-76).

C (see Fig. 2) and C 1 (see Fig. 3) - chamfers, determine the chamfer dimensions according to table 4, depending on the thread pitch. P - thread pitch to be determined from the table. 1, depending on d. The chamfer on the pin is made at an angle of 45 0, and in the socket - 120 0. On the working drawing of the stud, put down the dimensions indicated by the * sign (see Fig. 2).

2 . Draw a constructive simplified image of the stud connection. Make the main image in section. To speed up the drawing work, it is recommended to draw a nut and a washer in a stud connection (Fig. 4) in a simplified way, i.e. not according to the actual dimensions taken from the GOST0v tables, but according to the calculated data.

p, l*, l 1, l 0, d*, d in, h, n - see paragraphs 1 and 2 above;

d, b* - see individual task;

d 2 * - diameter of the hole for the stud, d 2 \u003d 1.1d;

D w - washer diameter, D w = 2.2d;

D is the diameter of the circumscribed circle, D = 2d;

D c - diameter of the conical chamfer (inscribed circle D c \u003d S *;

S* - turnkey size, S = 1.73d.

R = 1.5d, r - by construction.

Arcs of radii R and r must touch the horizontal planes limiting the nut from above (see image). On the drawing of the connection with a stud (Fig. 4), indicate the dimensions indicated by the * sign, preliminary, rounding them to a larger standard size op GOST 22034-76 - 22040-76 - l; according to GOST 5915-70-S; according to GOST 11284 -76 - d 2 (see table. 1.4).

Note:

1. Hatching of adjacent parts depicted in the section is performed in different directions.

2. In the drawing (Fig. 4), it is allowed, in order to simplify the thread run and chamfer C 1 (Fig. 3), not to be depicted.

Conventional designation of fasteners

STUD Md´l 58 GOST 22032-76 (fig. 1) - threaded stud Md, 3rd accuracy class, length l, threaded strength class 58, made of material carbon steel(in legend not specified), uncoated.

NUT 2 Md.5 GOST 5915-70 (Fig. 1) - hex nut, normal accuracy, version 2, with thread of the 3rd accuracy class, length (not indicated in the legend), uncoated.

WASHER d00.019 GOST 11371-78 (Fig. 1) - washer version I (not indicated in the legend), made of material of subgroup 00, coated with subgroup 01. Coating thickness 9 microns.

Note:

1. Write the inscriptions on the drawing in font No. 5.

2. Make the main inscription in accordance with GOST 2104-68 in form I.

3. When tracing, the thickness of the line of the visible contour should not be less than 0.6 mm and more than 1.5 mm.

Literature

2. Guidelines for threaded connections.

3. Fedorenko V.A., Shoshin A.I. Handbook of engineering drawing. L., 1984.

4. Godik V.I., Khaskin L.M. Reference guide to drawing. 1974.

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