Industry overview

According to the data of the national bureau of statistics, there were 1,416 enterprises in China's bearing manufacturing industry in 2011 (with annual sales revenue of more than 20 million yuan), and the annual industrial output value reached 193.211 billion yuan, up 27.59% year-on-year. Sales revenue was 191.097 billion yuan, up 30.30% year on year; Profits totaled 12.523 billion yuan, up 26.54% from the previous year. It is estimated that by 2015, China's bearing output is expected to exceed 28 billion sets, and the main business revenue is expected to reach 210 billion yuan, becoming the world's largest bearing production and sales base.

At present, China's bearing industry mainly faces three prominent problems: low production concentration, low r&d and innovation ability, and low manufacturing technology level.

First, the industry production concentration is low. In the world about 30 billion dollars of bearing sales, the world's eight largest multinational companies account for 75% to 80%. Germany's two biggest firms account for 90% of the total, Japan's five for 90% and America's one for 56%. And China's 10 largest bearing enterprises, such as tile shaft, sales only accounted for 24.7% of the industry, the production concentration of the top 30 is only 37.4%. Second, low r&d and innovation capacity. Weak basic theoretical research of the whole industry, weak participation in the formulation of international standards, less original technology, less patented products.

Bearing parameters

life

Under a certain load, the number of revolutions or hours experienced by a bearing before pitting occurs is called the bearing life.

The life of the rolling bearing is defined in terms of revolutions (or working hours at a certain speed) : the bearing within this life shall suffer from initial fatigue damage (spalling or defect) on any bearing ring or rolling body. However, no matter in the laboratory test or in the actual use, it is obvious to see that the bearing with the same appearance under the same working conditions, the actual life is very different. In addition, there are several different definitions of bearing "life", one of which is called "working life", which means that the actual life that can be achieved before a bearing is damaged is caused by wear, damage is usually not caused by fatigue, but by wear, corrosion, seal damage, etc.

In order to determine the standard of bearing life, bearing life and reliability are related.

Due to the difference in manufacturing accuracy and material uniformity, even if the same batch of bearings of the same material and the same size are used under the same working conditions, their service life is not the same. If the statistical life is 1 unit, the longest relative life is 4 units, the shortest is 0.1-0.2 units, the ratio of the longest to the shortest life is 20-40 times. The number of revolutions or hours experienced is called the rated life of the bearing [1].

Rated dynamic load

In order to compare the bearing capacity of anti-pitting bearing, when the rated life of the bearing is specified to be one million revolutions (106), the maximum load it can bear is the basic rated dynamic load, expressed in C.

In other words, under the action of rated dynamic load C, the reliability of the bearing that works for one million revolutions (106) without pitting failure is 90%. The greater the bearing C, the higher the bearing bearing capacity.

For the basic rated dynamic load

1. Centripetal bearing refers to the pure radial load

2. Thrust ball bearing refers to the pure axial load

3. Radial thrust bearing is the radial component produced by the pure radial displacement

At present, our design and manufacturing technology is basically imitated, and the product development ability is low, which is shown in: although the matching rate of domestic main engine reaches 80%, but high speed railway passenger cars, high grade cars, computers, air conditioners, high level rolling mill and other important main engine supporting and maintenance bearings, basically rely on imports.

Third, the level of manufacturing technology is low. China's bearing industry manufacturing process and process equipment technology development is slow, low CNC rate of car processing, low level of grinding automation, there are only more than 200 automatic production lines. The advanced heat treatment technology and equipment, which is crucial to the bearing life and reliability, such as controlled atmosphere protection heating, double thinning, bainite quenching and other low coverage, many technical problems have not been breakthrough. The research and development of new steel types of bearing steel, the improvement of steel quality, the research and development of lubrication, cooling, cleaning, abrasive and abrasive tools and other related technologies have not been able to meet the requirements of bearing product level and quality improvement. As a result, the working procedure capability index is low, the consistency is poor, the product processing size dispersion is large, the product intrinsic quality is unstable and affects the bearing precision, performance, life and reliability.