GOST 8530-90

Peculiarities

The slotted nut is supplied by a wide variety of companies and is present in the range of all leading manufacturers. Technically, it is "just" a metal ring. A thread is applied to the hole of the product from the inside. In this case, special slots are applied outside, which gave the name to such fasteners. These grooves are formed using milling.

The role of the grooves is to ensure the scrolling of the hardware around its axis. The number of slots must correspond to the section of the product. Slotted hardware is rarely used for conventional threaded joints, but they are in great demand in various industries, namely:

• machine tool building;
• automotive industry;
• other branches of mechanical engineering.

These are primarily units that contain shafts and other intensively rotating parts. The load on the slotted fastener is very high, so it must be extremely reliable and stable. For its manufacture, only steel with a strength of at least 36 HRS is used. The minimum hardening depth is 0.1 cm.

What it is?

The fastening element in the form of a self-locking nut is recommended as a connecting piece between elements of various structures. Standard hardware can only be screwed onto products that have threads. To make the connection stronger in this case, it can be strengthened with a grover, cotter pin, washer. The self-locking nut has a nylon retaining ring, so it can be used on its own without any additional fasteners. The advantage of hardware made in accordance with GOST is that it works with high quality and reliably connects the elements to each other. If the consumer prefers a self-locking nut, this means that he can be sure that this hardware is made of high quality steel and at the same time has a zinc anti-corrosion coating.

The construction of this type of hardware has the following components:

• an ordinary nut with six faces;
• board with one-sided increase;
• nylon spacer.

Species overview

Like any other hardware, the self-locking nut is available in several varieties.

• With nylon ring. This device looks like an ordinary nut, in the upper part of which a nylon ring is hidden. Hardware with insert can be made in strong and high strength class. This nut is usually used in conjunction with a bolt or screw.
• With a washer. Nuts of this type are considered a modern type of fastener, which is quite functional. The presence of a washer in the fastener prevents the connection from untwisting.
• Flanged is a nut that has a hexagonal shape. Such hardware is made of solid metal and can have a diameter from M5 to M16. It can be used in conjunction with fasteners that have a similar thread. Due to its high strength, the hardware is able to ensure the reliability of fastening.
• The self-locking cap nut is equipped with a nylon ring and is available in thread sizes from M4 to M16. An analogue of this hardware is considered to be a device without a non-metallic ring. These nuts are used to protect threaded fasteners from oil leakage. Self-locking fasteners have found their way into the assembly of vehicles and specialized types of equipment.

It is worth highlighting a few of the most common self-locking nut models.

• DIN 982. The galvanized product is equipped with a nylon ring. When using this hardware, you can get high locking parameters, as well as the reliability and durability of the fasteners. Consumers often give preference to this product, as it is able to fix details with high quality, while it does not need additional equipment.
• DIN 985 A2 and A4 are made of stainless steel.This type of fastener does not rust and protects the connection from the negative effects of environmental factors. During the manufacture of A4 nuts, manufacturers add molybdenum, so the product is reliably protected from chlorine and alkali.
• Nut DIN 6927 8.0 and 8.8. This nut model is equipped with a flange, so it can be used in various production areas. This hardware does not have a non-metallic retaining element. It has found its use in harsh conditions. In this case, the use of a washer or a grover is not required.

Marking

The dimensions of the nominal thread diameter can be:

• 6;
• 8;
• 10;
• 12;
• 14;
• 16;
• 18;
• 56;
• 80;
• 95;
• 170;
• 200 mm (there are also other dimensions).

Fastener packaging shall include the following:

• official trademark (sometimes in combination with the name of the company);
• conventional signs of hardware;
• net weight or quantity in pieces.

Only fasteners of a completely uniform type may be inserted in each package. That is, if round models are placed there, then square and any other shapes cannot be used. The same applies to dimensions, materials and coatings used. For the manufacture of slotted nuts, either stainless steel or brass can be used. Various coatings can be applied over the stainless steel.

Lock washer nuts are available in HM 3044 to HM 3192. Another range is HM 30/500 to HM 30/710. The mass of nuts in the marking is calculated on the assumption of a steel density of 7.85 g per 1 sq. see Sometimes it is practiced to apply not trapezoidal, but metric threads - which should also be marked.

V (V)

V

-77,

* Allowed instead of a chamfer with a rounded radius R = c and no chamfer for version 2.

Official edition

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Reprinting prohibited

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Notes:

1. It is allowed by agreement between the manufacturer and the consumer to manufacture nuts М45 * 1 -S-M125 with 4 splines.

2, Hook with the dimensions indicated in brackets is not recommended to be used,

GOST 11871-88

An example of a symbol for a nut of version 1, with a thread diameter d = 16 mm, with a fine thread pitch of 1.5 mm, with a thread tolerance of 6H, made of steel grade 35, coated with a chemical oxide impregnated with oil:

Nut М16X1,5-6N.05.05 GOST 11871-88 The same, made of brass L63, without coating:

Nut M16XL5-6H.32 GOST 11871-88 Same, version 2, with zinc coating 9 μm thick, chromated:

Nut 2 M16x 1.5-6N.019 GOST 11871-88

1.2. Thread - in accordance with GOST 24705.

1.3. The theoretical mass of steel nuts is shown in Appendix 1.

2. TECHNICAL REQUIREMENTS

2.1. The thread tolerance field is 6H in accordance with GOST 16093.

2.2. Fields of dimensional tolerances and tolerances of the location of surfaces must correspond to those indicated in table. 2.

Angle tolerances ± ■ -t; - according to GOST 8908.

It is allowed, by agreement between the manufacturer and the consumer, to manufacture nuts with a tolerance of the perpendicularity of the supporting surface to the thread axis L # - 11th degree of accuracy and surface roughness R_a: 1.6; 3.2; 6.3 instead of R_a\ 0.8; 1.6; 3.2 - respectively.

table 2

2.3. Grades of materials and their designations must correspond to those indicated in table. 3.

T a b l i

so-ts a 3

2.4. Nuts should be manufactured with coatings: zinc chromated; cadmium chromated; oxide impregnated with oil; phosphate, oil-impregnated or uncoated. The choice of coating for a specific material is in accordance with GOST 9.303. Technical requirements for coatings - in accordance with GOST 9.301.

The conventional designation of coatings is digital in accordance with GOST 1759.0.

2.5. Surface hardness of nuts splines - not less than 372HV or 38HRC_a... The depth of the hardened layer is at least 1 mm.

By agreement between the manufacturer and the consumer, it is allowed to manufacture nuts without heat treatment.

2.6. Surface defects of nuts - in accordance with GOST 1759.3.

3. ACCEPTANCE

What to consider when choosing?

All-metal products are good where small local distortion of the thread is acceptable. It is useful to be interested in whether the compression was performed by the radial method, by the axial method, at an angle to the axial thread from the end or at an angle to it from the end ledge. As for models with a spring-type threaded insert, they are equipped with a crimped coil, which guarantees the elasticity and reliability of the fastener clamping. All such products must have screw-in and out-out torques in accordance with the requirements of ISO 2320. The presence of a flange is welcome - it increases the overall reliability.

The tightening force can only be measured with instruments with a maximum error of 5%. Of course, all measurement results are checked against the regulatory documents and accompanying materials for the products. It is worth considering that models of nuts with a toothed support end on the flange are completely devoid of the prevailing moment. For them to work effectively, an exact match in the size of the attached part is required.

The described type, as well as fasteners with a captive toothed washer, are not reflected in any standard. Their locking properties are assessed based on the results of bench tests. In any case, you need to require a certificate of conformity ISO 2320. Of course, you need to contact only trusted companies, ideally - to direct manufacturers and their partners. The size of the fasteners is selected taking into account the problem being solved.

Lock nuts of modifications KMT (KMTA) can be used in conditions when it is important:

• maximum accuracy;

• ease of assembly;

• fixation reliability;

• adjustment (compensation) of angular deviations of the mating parts.

What it is?

The best way to explain what a lock nut is is to compare it with conventional samples. The "classic", when interacting with the bolt, guarantees a completely reliable connection. But this persists only until stable intense vibrations appear. After some time, they break the mechanical adhesion, and weakening, unscrewing begins. In theory, the stopper can be provided with locknuts and lock washers.

That is why lock (self-locking) nuts are in great demand, and their importance only grows over the years. There are quite a few types of such fasteners. The release of lock nuts in Russia is regulated by GOST standards.

So, hexagonal steel nuts with automatic locking must meet GOST R 50271-92. Products without galvanic coating are designed for temperatures from -50 to 300 degrees. In the presence of electroplating, the maximum permissible heating is 230 degrees. If the nut contains inserts made of non-metallic materials, the critical temperature level is 120 degrees. The standard regulates:

• test load voltage;

• Vickers hardness level;

• Rockwell hardness level;

• the amount of torque.

Self-locking nuts can save the prevailing torque even with multiple tightening and unscrewing. The chemical compositions of the steels used are also standardized. The nut inserts responsible for the prevailing torque cannot be made from steel alloys - completely different materials are needed for this purpose. Fasteners made of free-cutting steel also comply with the standard (if its use does not violate the supply agreement). The highest sulfur content in nut steel should be 0.24%.

The regulation strictly prohibits the use of hydrogen brittle material

This is especially important when applying special coatings.

The standard strictly stipulates the temperature requirements during operation - stable use at an air temperature of + 10 to + 35 degrees. If necessary, an additional study of these properties can be carried out by means of a full-scale test.The standard covers self-locking nuts made of solid metal or with non-metallic elements that have:

• triangular cutting ISO 68-1;

• combinations of diameters and pitches specified in ISO 261 and ISO 262;

• large groove gap (M3 - M39);

• small groove gap (М8х1 - М39х3).

How to twist them?

Application is perhaps the most important point when it comes to slotted nuts. By default, they are used to fix strictly coaxial parts. It is common practice to use radius (also called collet) keys. They have a grip in the form of an arc, ending in a trailer that looks like a hook in appearance. Of course, there can be no question of using a screwdriver.

The state standard has fixed 21 key formats for any nuts. These keys are necessarily made of steel with the addition of chromium. A swivel tool is sometimes used. It is sufficient to have one key for each size group and apply it as needed. In some cases, socket heads help to work with slotted nuts.

You can find out how to make a key for slotted nuts with your own hands from the video below.

Dimensions and weight

It is most convenient to present the relevant information in the form of a table.

M16 flange nuts are usually made of high-quality steels. Carbon metal grades are predominantly used. Considered interaction with various types of metric fasteners. This nut has the following dimensions:

• thread section from 5 to 20 mm;

• cutting step from 0.8 to 2.5 mm;

• height from 4.7 to 20 mm;

• turnkey width from 8 to 30 mm.

Typical for M18:

• cutting step 1.5 or 2.5 mm;

• section inside from 18 to 19.5 mm;

• head height - 14.3 - 15 or 16.4 mm;

• wrench size 27 mm.

M20 nuts have the following dimensions:

• height 2 cm;

• turnkey size 3 cm;

• flange section 4.28 cm.

According to DIN 6923, the weight of 1000 pieces of nuts is normally:

• M5 - 1 kg 790 g;

• M6 - 3 kg 210 g;

• M8 - 7 kg 140 g;

• M10 - 11 kg 900 g;

• M12 - 20 kg exactly;

• M14 - 35 kg 710 g;

• М16 - 40 kg 320 g.

M4 flange nuts are designed to create some pressure on the joint surface. Typically, a household package contains 25 pieces. Such products are made of galvanized steel. As for the M6 ​​hex nuts, they can be packaged in 0.581 kg. Basically, the right-hand thread predominates.

See the video about the flange nut below.

Operating tips

KMT (KMTA) high precision lock nuts are equipped with 3 pins, the distance between which is the same. It is these pins that must be tightened (tightened) together with the screws to fix the nut on the shaft. The end face of each pin is machined to match the shaft thread. Such nuts, however, cannot be used on shafts with grooves in the threads or on adapter sleeves.

The tightening speed of self-locking nuts should be the same, but not more than 30 turns per minute. Remember that the design torque may not provide the required pull. The reason is the pronounced spread of the coefficient of friction force. The conclusion is obvious: critical connections should be created only with careful control of the applied force. And, of course, you should take into account the recommendations of the manufacturers.

See below for nuts and their mounting features.

Features of operation

Self-Locking Nuts are advanced mechanisms that hold units together, which are subjected to high vibration loads and shock manipulation. If ordinary fasteners can crack after several blows, then self-locking does not. The finished hardware should be characterized by the reliability of locking, the ease of tightening the thread. In this case, the master should know that the thread of such a nut can be unscrewed and tightened more than once. In the principle of operation of self-locking hardware, there is a frictional locking, due to which a high level of friction in the threaded turns is ensured.Ideally, such a nut should be tightened on the correct side and then heat treated.

To prevent the fasteners from unwinding, it is worth following the following recommendations:

• use lock nuts;
• to carry out installation with a spring washer;
• fix the thread with a special type of glue;
• use nuts with nylon or polyamide ring.

Difficulties in using self-locking nuts include the following:

• the need for special surface treatments;
• creating additional stress in the case;
• danger of crushing the conical bearing surface;
• impossibility of full tightening in some cases.

Self-locking fasteners do not unwind, so their reliability is especially important in the manufacture of aircraft and missiles. They replaced standard nuts with less efficiency and difficulty in tightening. These mechanisms are not afraid of vibrations and vibrations, therefore, if there is a choice, experts advise buying self-locking fasteners.

For self-locking nuts, see the video below.