Nut symbol in the drawing. Bolts - GOST, designations

The studs are clean.

A stud is a cylindrical rod, at one end of which there is a thread for screwing the stud into the body of the part, and at the other end there is a thread for screwing a nut. Clean studs are made from clean-drawn calibrated metal with metric threads. Inch threaded studs can only be used as replacement parts and should not be used when designing new products. By type, studs are divided into two types: without a groove, conventionally designated by the letter A, and with a groove, designated by the letter B.

Depending on the depth of screwing of the stud into the body, the parts are distinguished: studs of the type I with a screw depth equal to 1.35 times the diameter and stud type II with a screwing depth equal to 1 diameter.
Depending on the length of the cut part for the nut, the studs are conventionally designated: for an ordinary nut with the letter O, for a castle nut or an ordinary one with a cotter pin - K. Clean studs are made from machine-cut steel according to GOST 1414-54, as well as from steel according to GOST: 1050-60, 4543-61 And 535-58 . In table No. 12 and table No. 13 and on (Fig. 448) The main dimensions of the studs are given.

Hairpin M10 X 60A10 OST 20001-38 - stud with main metric thread diameter 10 mm, length t = 60 mm, without groove, with a screwing depth of 1.35 d for a regular nut. Hairpin 3/8" X 60B11K OST 20001-38 - stud with inch thread with a diameter of 3/8 ", length t - 60 mm, with a groove and a screwing depth of 1b for a castle nut.

Bolts.

A bolt is a cylindrical rod, at one end of which there is a head, and at the other there is a thread made by knurling or cutting. The bolt head can be hexagonal (449, a), spherical (449, b) or conical (449, c).

The hex head (the most common) is a hexagonal regular prism with one chamfer, removed by turning the head along a conical surface at an angle 30° to the plane of the head in order to protect the corners from damage. According to the degree of manufacturing accuracy, bolts are divided into bolts of normal accuracy and increased accuracy. Table 14 and (Fig. 450) show the main dimensions of high-precision hex head bolts.

Examples of symbols: Bolt M10 X 50 GOST 7805-62- bolt with metric thread with coarse pitch, diameter 10 mm, length 50 mm, 3rd accuracy class (version I (Accuracy class 3 and version I are not indicated in the designation.)). Bolt II M12 X 1.25 X 75 cl. 2 GOST 7805-62 - bolt with metric thread with fine pitch (1.25 mm), diameter 12 mm, length 75 mm, 2nd accuracy class (version II).

Screws.

A screw is a rod with a head and threads. Screws are used to connect parts. Screws made by cutting are called turned, while screws made by stamping and with rolled threads are called knurled. The shape of the screw head depends on its purpose. There are screws with a screwdriver head (451, a) and a key head (451, b).

Table 15 shows several types of screws indicating the main dimensions.

Examples of symbols: Screw M12 X 30 cl. 2 GOST 1491-62 ; Screw M12 X 28 GOST 1476-58; Screw M8 X 30 GOST 1482-58.

Nuts.

The nuts are regular hexagonal prisms with a cut hole (Fig. 452), in which conical chamfers are removed from one or two bases.

If a hex nut has a groove for a cotter pin, the nut is called a slotted nut. A hex nut that has a cylindrical protrusion with grooves for cotter pins is called a castle nut. Nuts, depending on the nature of surface treatment, are of normal and increased accuracy. In addition to hexagonal ones, round nuts with slots for a key (453, a) are produced, as well as shaped wing nuts for tightening without a key (453, b).

Bolts, screws and nuts are made from the following grades of steel: Art. 3, Art. 4 and Art. 5 - according to GOST 380-60; steel 10, 15, 20, 25, 30 and 35 - according to GOST 1050-60; 35Х, 40Х and 45Х - according to GOST 4543-61; automatic steel A12, A20 and A30 - according to GOST 1414-54. In table 16 and on figure 454 The dimensions of high-precision hex nuts are given.

Example of a symbol: Nuts M16 class. 2 GOST 5927-62.

Washers.

Washers are used to protect the surface of parts from damage and to prevent self-unscrewing of bolts, screws and nuts. The most widely used washers are clean and black. Clean washers are called turned ones, black washers are called stamped ones.

Washers are made from the following grades of steel: St. 0, St. 1, Art. 2, Art. 3 and Art. 4 - by GOST 380-60; Steel 08, 10, 15, 20, 25, 30, 35 and 40 - each GOST 1050-60; A12 - by GOST 1414-54. In cases where drawings of clean and black washers are made, according to which these washers will not be manufactured, you can draw them in relative sizes depending on the given outer diameter of the thread d 0 (Fig. 455).

Examples of symbols: Washer 20 GOST 6957-54; Washer 20 GOST 6959-54.

Adjustable cotter pins.

An adjustable cotter pin is a double rod bent from a piece of wire of a special section, which serves to hold, for example, a nut from self-unscrewing while the machine is operating. The cotter pin is inserted into the hole located at the end of the bolt or stud, and then its ends are separated. Adjustable cotter pins must be made from low-carbon steel wire of standard steel grades with a carbon content of no more than 0.20%. In table 17 and on figure 456 The dimensions of the adjustable cotter pins are given.

The length of the cotter pin is selected within the specified limits: up to 12 mm - every 2 mm; from 15 to 50 mm - after 5 mm and from 50 to 100 mm - after 10 mm.
An example of a symbol for a cotter pin with a nominal diameter d = 3 mm, length t = 15 mm: Cotter pin 3 X 15 GOST 397 - 54.

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

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

Bolted connections also have their disadvantages. These include, for example, that to implement it, there must be enough space on the parts being connected to accommodate the head of a screw or nut. In addition, during the process of screwing or unscrewing nuts, you need to hold the screw head to prevent rotation. It should also be noted that compared to, say, a screw connection, a bolted connection leads to a greater increase in the mass of the finished product.

If for some reason it is impossible to install a bolted connection or it turns out to be irrational, then screws and studs are used. This, for example, is usually done when there is no way to provide access to the head (nut) or there is simply no space to place it. Another common case is the significant thickness of the parts, which results in the need for deep drilling and the use of long bolts.

Washers are used as backing 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 (for example, wood, aluminum, plastic, etc.). In addition, with the help of washers, it is possible to prevent parts from being scratched when screwing a screw or nut, and also to compensate for significant hole clearance. 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 conventional images on general view drawings and assembly drawings images fasteners for all industries and construction are established by a document such as GOST 2.315 - 68.

Selecting a conventional or simplified image of fasteners in the drawings general view and assembly drawings is made depending on what exactly the scale is and what the purpose of each specific technical document. Conventional images are used for those fasteners whose rod diameters, when depicted in the drawings, are 2 millimeters or less. In this case, the rule that a complete picture of the nature of the connection must be given should be fully observed.

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

Simplified and conventional images of fasteners
Simplified image	Conditional image	Name
		Hex Bolts
		Square Head Bolts
		Hammer Head Bolts
		Button head bolts
		Round Head Hinge Bolts
		Swivel bolts with fork
		Foundation bolts
		Button head screws
		Pan head screws
		Pan Head and Sphere Screws
		Phillips Button Head Screws
		Phillips Pan Head Screws
		Allen screws
		Countersunk head screws
		Countersunk screws
		Countersunk Phillips Screws
		Self-tapping screws with cylindrical head
		Self-tapping screws with a countersunk cross head
		Round nuts
		Hex nuts
		Hexagon slotted and castle nuts
		Wing nuts
		Round head screws
		Countersunk screws
		Countersunk head screws
		Hairpins
		Plain washers, lock washers, etc.
		Lock washers with tongue
		Spring washers
		Cylindrical pins
		Conical pins
		Nails
		Cotter pins
		Threaded inserts

Examples of simplified and conditional images fasteners in connections
Simplified image	Conditional image

If objects on 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 manner, and in other places it is enough to simply use axial or center lines.

Designation of fasteners in the drawing

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

If there are identical fastening groups on the construction drawings, then it is permissible to outline 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.

Same fasteners

To depict the slots on the fastener heads, one solid line is used.

Designation of splines 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 splines

When depicting the thread on the rod In the front and left views, the outer diameter of the thread is shown with a solid main line, and the inner diameter is shown with a solid thin line (Fig. 1.6, a). In the view on the left, a chamfer is not depicted in order to be able to mark the internal diameter of the thread with a continuous thin line, open to one quarter of the diameter of the circle. Please note that one end of the circular arc does not reach the center line by approximately 2 mm, and its other end intersects the second center line by the same amount. The end of the cut part is shown as a solid main line.

When and image of thread in hole in the front view, the outer and inner diameters of the thread are shown with dashed lines (Fig. 1.6, b). In the view on the left, the chamfer is not shown, and the outer diameter of the thread is drawn as a continuous thin line, open to one quarter of the circle. In this case, one end of the arc is not completed, and the other crosses the center line by the same amount. The internal diameter of the thread is drawn as a solid main line. The thread boundary is shown with a dashed line.

In the section, the thread in the hole is shown as follows (Fig. 1.6, c). Outside diameter draw with a solid thin line, and the inner one with a solid main line. The thread boundary is shown by a solid main line.

The type of thread is conventionally designated:

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 - external conical pipe (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 is not indicated after the outer diameter, this means that the thread has a large pitch. The thread pitch is selected according to GOST.

When making drawings of 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 rod;

2. it is allowed not to show the gap between the shaft of a bolt, screw, stud and the hole in the parts being connected;

3. when constructing a drawing of bolted, screw, stud connections, do not draw invisible contour lines on the images of nuts and washers;

4. bolts, nuts, screws, studs and washers in the drawings of bolted, screw and stud connections are shown uncut if the cutting plane is directed along their axis;

5. When drawing a nut and a bolt head, a screw, take the side of the hexagon equal to the outer diameter of the thread. Therefore, in the main image, the vertical lines delimiting the middle edge of the nut and bolt head coincide with the lines outlining the bolt shank.

When making drawings of detachable connections, the following errors are most common:

1. the thread on the rod in the blind hole is incorrectly marked;

2. no thread border;

3. the thread on the chamfer is shown incorrectly;

4. pipe threads are incorrectly marked;

5. The distance between thin and solid lines when depicting a thread is not maintained;

6. The connection of the internal and external threads (connection of the fitting to the pipe) is not made correctly.

Bolted connection

A bolt is a fastening threaded part in the form of a cylindrical rod with a head, part of which is threaded (Fig. 1.13).

The size and shape of the head allows it to be used for screwing a bolt using a standard wrench. Typically, a conical chamfer is made on the bolt head, smoothing out the sharp edges of the head and making it easier to use. wrench when connecting a bolt to a nut.

Rice. 1.13. Photo of a hex head bolt and a screwed nut.

The fastening of two or more parts using a bolt, nut and washer is called a bolted connection (Fig. 1.14) .

The bolted connection consists of:

§ parts to be connected (1, 2);

§ washers (3);

§ nuts (4),

§ bolt (5).

For the passage of the bolt, the parts to be fastened are smooth, i.e. without thread, coaxial cylindrical holes with a 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.

Sequence of drawing a bolted connection:

1. Depict the parts being connected.

2. Depicts a bolt.

3. Depict a puck.

4. Depict a nut.

For educational purposes, it is customary to draw a bolted connection by relative dimensions. The relative dimensions of the bolted connection elements 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.

There are various types of bolts, differing from each other in the shape and size of the head and shaft, thread pitch, manufacturing accuracy and performance.

Hex head bolts have from three (Fig. 1.15) to five designs:

§ Version 1 – without a hole in the rod.

§ Version 2 – with a hole in the rod for a cotter pin.

§ Version 3 – with two through holes in the head, intended for cotter pinning with wire in order to prevent the bolt from self-unscrewing.

§ Version 4 – with a round hole in the end of the bolt head.

§ Version 5 – with a round hole in the end of the bolt head and a hole in the rod.

When depicting a bolt in a drawing, two types are performed (Fig. 1.16) according to general rules and apply the dimensions:

Rice. 1.14. Bolted connection

1. bolt length L;

2. thread length Lo;

3. spanner size S ;

4. thread designation Md .

The height H of the head in the length of the bolt is not included.

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 bolt version

Examples of bolt symbols:

1. Bolt Ml2 x 60 GOST 7798-70 - with a hex head, first design, 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.

Hairpin connection

A stud is a fastener, the rod is threaded at both ends (Fig. 1.18).

A hairpin connection is a connection of parts made using a hairpin, one end of which is screwed into one of the parts being connected, and the attached part, a washer, and a nut are put on the other (see Fig. 1.19). Used for tightening and fixing elements of metal structures with metric threads at a given distance.

Rice. 1.20. Simplified illustration of a stud joint

Connecting parts with a pin is used when there is no room for a bolt head or when one of the parts being connected has a significant thickness. In this case, it is not economically feasible to drill a deep hole and install a long bolt. The pin connection reduces the weight of the structures.

The design and dimensions of the studs are determined by standards depending on the length of the threaded end l1 (see Table 1).

The drawing of the hairpin connection is carried out in the following sequence and according to the parameters indicated in Fig. 1.19:

1. Show a part with a threaded hole.

2. Depict a hairpin.

3. Draw an image of the second part to be connected.

4. Depict a puck.

5. Depict a nut

Examples of stud symbols:

1. Stud M8 x 60 GOST 22038-76 - with a large metric thread with a diameter of 8 mm, stud length 60 mm, designed for screwing into light alloys, length of the screwed end 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

A screw is a threaded rod with a head whose shape and dimensions differ from the heads of bolts. Depending on the shape of the screw head, they can be screwed in with keys or screwdrivers, for which purpose a special slot (slot) for a screwdriver is made in the screw head (Fig. 1.21). Screw differs from a bolt by the presence of a slot (slot) for a screwdriver.

Rice. 1.22. Screw connection

Screw connection includes parts to be connected and screw and washer. In connections with countersunk screws and set screws, do not use a washer.

According to their purpose, screws are divided into:

§ fastening - used to connect parts by screwing a screw with a threaded part into one of the parts being connected.

§ installation - used for mutual fixation of parts.

In set screws, the rod is completely threaded and they have a cylindrical, conical or flat pressure end (Fig. 1.23).

Rice. 1.23. Set screws

Depending on the operating conditions, screws are manufactured (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 keyed head and with corrugation.

In the drawing, the shape of a slotted screw is completely conveyed by one image on a plane, parallel to the axis of the screw. In this case 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.

Sequence of drawing a screw connection:

1. Depict the parts being 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. The cross-section shows the threaded hole partially closed by the threaded end of the screw rod. The other connecting part is shown with a gap existing between the cylindrical hole of the upper connecting part and the screw.

3. Depict a screw.

Examples of screw symbols:

1. Screw M12x50 GOST 1491-80 - with a cylindrical head, version 1, with M12 thread with a coarse pitch, 50 mm long;

2. Screw 2M12x1, 25x50 GOST 17475-80 - with a countersunk head, version 2, with a fine metric thread with a diameter of 12 mm and a pitch of 1.25 mm, screw length 50 mm.

Picture of nut and washer

screw - a 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 connected.

Depending on the name and operating conditions, the nuts are hexagonal, round, wing, shaped, etc. Hexagonal nuts are most widely used.

Nuts are manufactured in three designs (Fig. 1.25):

Version 1 - with two conical chamfers;

version 2 - with one conical chamfer;

version 3 - without chamfers, but with a conical protrusion at one end.

The shape of the nut in the drawing is conveyed in two ways:

§ on the projection plane, parallel axis nuts, combine half the view with half the frontal section;

§ on a plane perpendicular to the nut axis, from the chamfer side.

The drawing indicates:

§ thread size;

§ size S Full construction;

§ nut designation according to the standard.

Rice. 1.25. Nut shapes

Examples of nut symbols:

Nut M12 GOST 5915-70 - first version, with a thread diameter of 12 mm, large thread pitch;

Nut 2M12 x 1.25 GOST 5915-70 - second version, with 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 flatness of the washer increases the supporting surface and protects the part from scuffing when screwing the nut with a wrench.

Round washers according to GOST 11371-78 have two designs (Fig. 1.26):

§ execution 1 - without chamfer;

§ version 2 - with chamfer.

The shape of a round washer is conveyed by one image on a plane parallel to the axis of the washer.

The internal diameter of the washer is usually 0.5...2.0 mm larger than the diameter of the bolt rod on which the washer is placed. The symbol of the washer also includes the thread diameter of the rod, although the washer itself does not have a thread.

Examples of washer symbols:

Rice. 1.26. Shapes of washers

Washer 20 GOST 11371-78 - round, first version, for bolt with M20 thread;

Washer 2.20 GOST 11371-78 - the same washer, but of a second design.

For the purpose of protection threaded connection against spontaneous loosening under conditions of vibration and alternating load, the following is used:

§ spring washers according to GOST 6402-70;

§ lock washers with tabs.

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

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

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

16.1. Bolts

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

Bolt symbol : Bolt 2 M 16 × 1.5. 6g × 75. 68. 09 GOST 7798-70-2 – version; M 16 – type and size of thread; 1.5 – fine thread pitch value; 6g – tolerance range; 75 – bolt length ι ; 68 - a symbol of a 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, with the parts being connected being clamped between the nut and the head of the bolt.

Nut symbol : Nut M 24 -6N. 6 GOST 5915-70 – hex nut version 1 according to GOST 5915-70 with a tolerance range of 6H, strength class 6, without coating. Most often, hex nuts are used, the design and dimensions of which are determined by GOST. They are divided into regular (Figure 16.2), slotted (Figure 16.3) and crown (Figure 16.4).

Conventional nuts are available in three designs 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 with a head at one end (Figure 16.6). Heads come in different shapes: cylindrical, semicircular, countersunk, etc.

There are two types of screws - mounting and installation screws. Set screws are used to adjust gaps and secure 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 range, 50 – length, 48 – strength class.

Figure 16.6

16. 4 Studs

A stud is used in cases where the parts do not have room to accommodate the bolt head, or if one of the parts is significantly thicker, then using a bolt that is too long is uneconomical (Figure 16.7).

The stud is a cylindrical rod with threads at both ends. One threaded end of the pin 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 metric thread with coarse pitch; 6g – tolerance range; 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 (mounting) end, taking into account the thread run-out. The screwing depth is selected: ℓ 1 =d – in parts made of steel, bronze, brass, titanium; ℓ 1 =1.25 and 1.6 – in parts made of malleable and gray cast iron; ℓ 1 =2d and 2.5d – in parts made of light alloys.

Metric thread (GOST 9150-2002)

Example of a symbol:

M 20×1.5 – metric cylindrical thread with a rod diameter of 20 mm and a thread pitch of 1.5 mm;

M 20× Ph 3R 1.5 - metric cylindrical thread with a rod diameter of 20 mm, two-start with a thread pitch of 1.5 mm;

M 20×1.5- L.H.– metric cylindrical thread with a rod diameter of 20 mm and a thread pitch of 1.5 mm, left;

MK 20×1.5 – metric conical thread with a rod diameter of 20 mm and a thread pitch of 1.5 mm;

Inch thread

Example of a symbol:

1′ – inch cylindrical thread with a rod diameter of 25.4 mm;

⅜′ – inch cylindrical thread with a rod diameter of 9.5 mm (⅜′);

1' L.H.– inch cylindrical thread with a rod diameter of 25.4 mm, left;

TO 1′ – inch conical thread with a rod diameter of 25.4 mm;

Cylindrical pipe thread (GOST 6357-81)

Example of a symbol:

G 1 – cylindrical pipe thread with a nominal diameter of 1′;

G ⅜ L.H.– cylindrical pipe thread (⅜′) left;

Conical pipe thread (GOST 6211-81)

Example of a symbol:

R 1½ – external conical pipe thread;

Rc 1½ – internal conical pipe thread;

Example of a symbol:

Tr 36×6 – trapezoidal thread with a rod diameter of 36 mm and a pitch of 6 mm;

Tr 36×12( R 6) – trapezoidal thread with a rod diameter of 36 mm, two-start, pitch 6 mm;

Tr 36×6 L.H.– trapezoidal thread with a rod diameter of 36 mm and a pitch of 6 mm, left;

Persistent thread (GOST 10177-82)

Example of a symbol:

S 36×5 – persistent thread with a rod diameter of 36 mm and a pitch of 5 mm;

S 36×5 L.H.– persistent thread T with a rod diameter of 36 mm and a pitch of 5 mm, left;

Rectangular thread (non-standard)

Rectangular thread (Fig. 85) is non-standard, which means it does not have a symbol. Therefore, the drawing must indicate all the dimensions necessary for its manufacture.

Rice. 85 Rectangular thread

In a threaded connection, one part has an external thread and the other has an internal thread. External thread in a connection it is a male surface, and the part that has it is called a “bolt” (screw, stud). Internal thread is a covering surface and is called a “nut” (socket, etc.).

In the drawings, the thread is shown conventionally: a solid main line shows the tops of the turns, and a solid thin line shows the troughs of the turns (Fig. 86).

Rice. 86 Image of thread in the drawings: A– external; b- internal

On sections of a threaded connection in the image on a plane parallel to its axis, only that part of the thread that is not covered by the thread of the rod is shown in the hole (Fig. 87).

Rice. 87 Illustration of thread in connection

The correct application of the thread designation on the drawings is given in table. 2.

Fasteners

Fasteners include bolts, screws, studs, nuts, washers, cotter pins.

The shape, dimensions and other characteristics of fasteners (such as material, strength class, type of coating, etc.) are standardized, but without special knowledge they cannot be reasonably assigned. Therefore, in the “Engineering Graphics” course, some parameters are not indicated in the symbols of fasteners. Most fastener threaded products are manufactured with metric threads, large or fine pitch. Drawings of fasteners are made according to actual dimensions, which are established by the relevant standard.

Bolts

A bolt is a cylindrical rod, at one end of which there is a head (hexagonal, square, round or special), and at the other end there is a thread for screwing on a nut.

table 2

Thread type	Symbol of thread	Designation of threads on images in a plane parallel to the thread axis	Designation of threads on images in a plane perpendicular to the thread axis
on the rod	in the hole	on the rod	in the hole
Metric thread	M
Trapezoid thread - long single start	Tr
Thread persistent	S
Cylindrical pipe thread	G
Conical pipe thread: external internal	R Rc

Rice. 88 Bolts

An example of a complete symbol for a high-precision bolt with thread diameter d= 16 mm long l= 60 mm, strength class 5.8, version 2, fine pitch R=1.5 mm, with tolerance range 69, uncoated:

Bolt 2M16´1.5.6g´60.58 GOST 7798-70.

Bolt designation on training drawings:

Bolt 2M16´1.5´60 GOST 7798-70.

Hairpins

Hairpin is called a cylindrical rod, at both ends of which there is a metric thread (Fig. 89). Studs are used to connect parts when there is no space to place a bolt head or nut, and also when one of the parts being connected is of significant thickness, which makes it uneconomical to install a long bolt.

Threaded end of stud l 1, screwed into the part, is called a landing. Its length depends on the strength and ductility of the material from which the part is made.

For durable and ductile materials (steel, bronze, brass, etc.)

l 1 = d(GOST 22032-76, GOST 22033-76).

For gray and ductile cast iron:

l 1 = 1,25d(GOST 22034-76, GOST 22035-76),

l 1 = 1,6d(GOST 22036-76, GOST 22037-76).

For parts made of light alloys:

l 1 = 2d(GOST 22038-76, GOST 22039-76),

l 1 = 2,5d(GOST 22040-76, GOST 22041-76).

On the other threaded end of the stud l 0 the nut is screwed on. Stud length l conventionally consider the length of its rod without the length of the landing end l 1 (see Fig. 89).

An example of a symbol for a stud with thread diameter d= 20 mm, in increments P= 1.5 mm, with tolerance range 6 g, length l= 100 mm, with screw-in threaded end length l 1 =d, normal accuracy, strength class 5.8, uncoated:

Hairpin M20´1.5-6g´100.58 GOST 22032-76.

Designation of the same stud on training drawings:

Hairpin M20´1.5´100 GOST 22032-76.

Screws

A screw is a cylindrical rod with a head at one end and a metric thread at the other. Screws most often have a slot in the head for a screwdriver, but there are screws with hexagonal and square heads for a wrench.

Depending on their purpose, screws are divided into fastening, setting, adjusting, etc. Set screws are used to adjust gaps and fix parts during assembly. The most common type in mechanical engineering are fastening screws for metal. Depending on the operating conditions, these screws are made with a cylindrical shape, GOST 1491-80 (Fig. 90, A), semicircular, GOST 17473-80 (Fig. 90, b), semi-secret, GOST 17474-80 (Fig. 90, V) and secret, GOST 17475-80 (Fig. 90, G) heads. The determining dimensions for all screws are the thread diameter d and length l. For length l Most machine screws accept the length of their shank (excluding head).

For countersunk head screws, size l includes shaft length and head height (see Fig. 90, G).

Screw A M8´1-6g´50.48 GOST 17473-80.

The same on the training drawings:

Screw M8´1´50 GOST 17473-80.

A	b
V	G
Rice. 90 Screws

Nuts

A nut is a part that has a threaded hole for screwing onto a bolt or stud with the same thread. Standard nuts can be hexagonal (Fig. 91, A), slotted and crowned (Fig. 91, b), round (Fig. 91, V), lamb (Fig. 91, G) and etc.

A	b	V	G
Rice. 91 Nuts

Hex nuts are divided according to height into normal, low, high and extra high.

Nuts are manufactured with normal and high precision. Some hex nuts are manufactured in two versions (Fig. 92): version 1 - with two chamfers; version 2 – with one chamfer.

An example of a symbol for a hex nut (normal accuracy), version 1 (with two chamfers), thread diameter d= 30 mm, fine pitch P = 2 mm , with tolerance range 7 N, strength class 5, uncoated:

Nut M30´2.5 GOST 5915-70.

The same on the training drawings:

Rice. 92 Nut versions

Washers

A washer is a stamped or turned ring that is placed under nuts or heads of bolts and screws.

Round washers (GOST 11371-78) have 2 designs (Fig. 93): version 1 – without chamfer; version 2 – with chamfer.

An example of a symbol for a normal washer, version 2, for a fastener with a thread diameter of 30 mm, set thickness, made of material group 01, with coating 01, thickness 9 microns:

Washer 2.30.01.019 GOST 11371-78.

The same on the training drawings:

Washer 2.30 GOST 11371-78.

Rice. 93 Washer designs