Lock Nut Standard

The hardware and electrical industry covers everything, with an annual output value exceeding one trillion yuan. The standard parts industry is one of the important branches, and lock nuts are an important product category in the standard parts field.

Lock nuts are usually used in many fields such as machinery and engineering. Although they can be bought in the general hardware and building materials market, many people are not aware of this common but unfamiliar nut product. Here, Xiaorui will take you to understand the summary of knowledge about lock nuts and the complete specifications of lock nuts.

   1. Definition of lock nut

  Lock nut is a kind of nut widely used in machinery and other industries. Its working principle is to use the friction force between the nut and the bolt for self-locking. However, the reliability of this self-locking will be reduced under dynamic load. In some important occasions, we will take some anti-loosening measures to ensure the reliability of nut locking. Lock nuts are available in hardware stores.

  Experts from China Hardware Machinery Grid said that the anti-loosening effect of the lock nut mainly depends on the interaction force between the nut and the bolt meshing thread. There are many ways to improve the interaction force between the meshing threads, such as the improvement of the thread structure of the Spirax nut, the nylon roughening of the nylon nut, and the surface treatment of the thread, etc.

   2. Classification of lock nuts

   The first is to screw two identical nuts on the same bolt, and add a tightening torque between the two nuts to make the bolt connection reliable.

  The second type is a special anti-loosening nut, which needs to be used together with an anti-loosening washer. The anti-loosening nut specially used in the hardware and electrical industry is not a hexagonal nut, but a round nut with 3, 4, 6 or 8 gaps on the circumference of the nut (depending on the size of the nut and the product series of the manufacturer) ), these notches are not only the focus of the tightening tool, but also the snap-in place of the lock washer bayonet.

The third is to drill through threaded holes (usually 2, distributed at 90 degrees on the outer surface) from the outer surface of the nut to the inner thread surface, which are used to screw in small-diameter countersunk screws. Apply a centripetal force to prevent the lock nut from loosening. Lock nuts of good quality sold in the hardware accessories market are inlaid with small copper pieces consistent with the lock nut thread on the inner surface of the nut, which is used to prevent the radial jacking screw from being damaged due to direct contact with the locked thread. the latter. This kind of lock nut is gradually applied in the shaft end locking of rotating parts, such as the anti-loosening of the bearing at the installation end of the ball screw.

The fourth type of lock nut is composed of two parts, each part has staggered cams, because the slope angle of the internal wedge design is larger than the nut angle of the bolt, this combination will tightly bite into a whole, when vibration occurs At the same time, the raised parts of the DISC-LOCK anti-loosening nuts are staggered with each other to generate lifting tension, so as to achieve a perfect anti-loosening effect.

The fifth method is structural anti-loosening. By improving the design of the thread structure, a self-locking function can be obtained without resorting to other external factors. Therefore, its applicability is wider than the above-mentioned methods, and the requirements for the environment are also relatively high. low, such as Spirax locknuts.

   Locknuts include many types, such as nylon nuts, and flange nuts. In short, this kind of locknut is used to prevent loosening. Twist the nut onto the screw, screw, bolt, etc., so that it will not come loose. It enables them to be actively connected together to make them firm and achieve a high degree of stability.

  3. National standard lock nut specifications

  GB/T 6182-2000 Type 2 non-metallic insert hexagon lock nut

  GB/T 6183.1-2000 Non-metallic insert hexagon flange lock nut

  GB/T 6183.2-2000 Non-metallic insert hexagon flange lock nuts - fine thread

  GB/T 6184-2000 Type 1 All Metal Hexagon Lock Nuts

  GB/T 6185.1-2000 Type 2 All Metal Hexagon Lock Nuts

  GB/T 6185.2-2000 Type 2 All Metal Hexagon Lock Nuts Fine Thread

  GB/T 6186-2000 Type 2 All Metal Hexagon Lock Nuts, Grade 9

  GB/T 6187.1-2000 All metal hexagon flange lock nuts

  GB/T 6187.2-2000 All metal hexagonal flange face lock nuts fine thread

  GB/T 889.1-2000 Type 1 non-metallic insert hexagon lock nut

  GB/T 889.2-2000 Type 1 non-metallic insert hexagonal lock nut fine thread

         4. Standard size

  ①This standard specifies the size, technical requirements, acceptance rules and measurement methods of lock nuts (nuts for short) and locking devices in the hardware and electrical industry. This standard applies to the design, production, inspection and user acceptance of nuts and locking devices for tapered bushes.

  ②Referenced standards The provisions contained in the following standards constitute the provisions of this standard by being quoted in this standard. At the time of publication, the editions indicated were valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest edition of the following standards. GB/T 192—1981 Basic tooth profile of ordinary thread GB/T 196—1981 Basic size of ordinary thread (diameter 1~600 mm) GB/T 272—1993 Code number method of rolling bearing GB/T 699—1988 Technical conditions of high-quality carbon structural steel GB/T 1804—1992 General tolerances Unmarked tolerances for linear dimensions GB/T 2516—1981 Ordinary thread deviation table (diameter 1~355 mm) GB/T 5796.1—1986 Trapezoidal thread profile GB/T 5796.3—1986 Trapezoidal thread basic Size GB/T 5796.4—1986 Trapezoidal thread tolerance GB/T 6930—1986 Rolling bearing vocabulary GB/T 8597—1988 Rolling bearing packaging JB/T 3574—1997 Rolling bearing product mark JB/T 8921—1999 Rolling bearing and its commodity parts inspection rules.

          ③Terminology The terms used in this standard comply with the provisions of GB/T 6930.

  This standard stipulates the marking system, indicators, test methods and signs of the mechanical and working performance of the effective torque steel hex lock nuts. This standard is applicable to the hardware accessories market, which are made of carbon steel or alloy steel, have a width across sides that meets the requirements of GB 3104, a nominal height ≥ 0.8D, require a specified guaranteed load and effective torque, and have a thread diameter of 3~39mm. Coarse thread 6H grade nuts. Except for the effective torque part, the thread size and tolerances are in accordance with GB 193, GB 196 and GB 197.

  The operating temperature range of the nut shall comply with:

           All-metal nuts without electroplating: -50℃~+300℃.

           Electroplated full metal nut::-50℃~+230℃ 

           Nuts embedded in non-metallic components: -50℃~+120℃ 

           This standard does not apply to nuts with special performance requirements (such as weldability and corrosion resistance). For fine tooth lock nuts or thin nuts made of carbon steel or alloy steel made of stainless steel, non-ferrous metals, the performance indicators and test methods of effective torque specified in this standard can be adopted after mutual agreement.