Matching and preloading of household appliance bearings

Core Tip: The role of pre-tightening Pre-tightening refers to the use of the bearing in the play by changing the relative position of the inner and outer rings before the bearing is loaded. For household appliances bearings, the main pre-tightening
Preloading effect
Preloading refers to the use of the bearing in the play by changing the relative position of the inner and outer rings before the bearing is loaded. For household appliances bearings, the main role of pre-tightening is to improve bearing stiffness and suppress vibration noise.
Preload on the bearing noise
When the bearing is subjected to radial load, due to the radial clearance, only part of the steel ball is subjected to load (ABC in the figure), which is called the bearing area, and the other is called the non-bearing area. During the movement of the steel ball from the D to the D' in the non-bearing zone, the magnitude and direction of the combined force of the self-weight and the centrifugal force of the steel ball constantly change, and the steel balls alternately collide with the inner and outer ring raceways, so that abnormal noise is generated inside the bearing. This abnormal sound can be eliminated by preloading the bearing.
However, if the pre-tightening force is too large, the bearing friction increases, the temperature rises, and the noise life of the bearing decreases. Therefore, it is important to choose a suitable preload.
The structure of NSK common dust cover and sealing ring is shown in the figure below. The dust cover (ZZ) is stamped from a steel plate, and the seal ring is made of rubber covered with steel. Among them, the sealing ring is divided into two types: non-contact type (VV) and contact type (DDU, DDW).https://www.supplyforever.com/

The characteristics and development history of foreign bearing industry

Core Tip: The development of the world's bearings has gone through three stages, in which it has experienced many difficulties and obstacles, and finally achieved the glory of the bearing industry. The world's bearing industry emerged from the end of the 19th century to the second
The development of the world's bearings has gone through three stages, in which it has experienced many difficulties and obstacles, and finally achieved the glory of the bearing industry.
The world's bearing industry began in the late 19th century to the early 20th century. In 1880, the United Kingdom began to produce bearings. In 1883, Germany established the world's first bearing company (FAG George Shaver). In 1889, the United States opened the ND bearing factory (now the General Motors Bearing Company's new Diocletian Hyde Bearing Division). Other large bearing companies in Europe and the United States basically laid the foundation for today in the early 20th century. After the Japanese bearing industry was formed in Europe and the United States, SKF Sweden provided samples to Japan in 1910, making the "bearing" appear in Japan for the first time alone. Since then, Japan NSK, NTN and other bearing companies have been established in 1914 and 1918. The bearing industry in the third world countries started later, and it is in a relatively backward situation like the entire science and technology and machinery industry.
Generally speaking, the formation and development of the world bearing industry has gone through three stages:
The first phase, the initial stage of the world bearing industry, was from the end of the 19th century to the beginning of the 20th century. At that time, bearing inventions and applications have been around for a while, and the industrial production of bearings has grown from scratch, just starting, quite naive. The main features are:
1. The production scale is extremely small. A large factory has only a dozen to a few hundred people. The daily output is only a few sets to several hundred sets, which belongs to hand workshop production;
2, the equipment is simple, the technology is backward, mostly based on experience;
3, the material is mainly carbon steel, the precision is not high, the price is expensive;
4, very few varieties, the use is very limited. At that time, bearing production technology was only in the hands of a few companies such as the United Kingdom, Germany, Sweden, and the United States.
The second phase, the growth phase of the world's bearing industry, was about the end of the First World War and after the Second World War. The two world wars stimulated the development of military industry, the increasing position of bearings in the military industry, coupled with the rapid development of science and technology, the short-term stability after World War I and the urgent need for arms in World War II, prompting the rapid development of the world bearing industry. The main features are:
1. The scale of production has expanded rapidly and the output has increased rapidly. The annual output of major bearing producing countries exceeds 35 million sets;
2, the production equipment is perfect, the technical means is advanced, and the mass production is generally adopted;
3. The bearing material has been developed to alloy steel such as chrome steel, and the quality of the product has been greatly improved;
4, bearing varieties increased, widely used in automobiles, aircraft, tanks, armored vehicles, machine tools, instruments, meters, sewing machines and many other fields. During this period, people's awareness and attention to bearings rose to an unprecedented height.https://www.supplyforever.com/