Backstops are used extensively on pumps used in the primary and secondary cooling systems of power generating equipment.
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The History of Bearing and How to Identify High Quality BearingHave Read 16604/03/2020
Bearing is an important part of modern mechanical equipment.Its main function is to support the mechanical rotating body, reduce its friction coefficient in the process of motion, and ensure its rotation accuracy.
Early linear motion bearings consisted of a row of wooden poles placed under a row of pry plates.Modern linear bearings work on the same principle, but sometimes balls are used instead of rollers.The simplest rotary bearing is the bush bearing, which is simply a bushing between the wheel and the axle.This design was then replaced by rolling bearings, in which the original bushing was replaced by a number of cylindrical rollers, each of which acted like a separate wheel.
An early example of a ball bearing has been found on a Roman ship built in 40bc in lake nami, Italy: a wooden ball bearing used to support a rotating table.Leonardo Da Vinci is said to have described a ball bearing around 1500.One of the most important factors in ball bearing immaturity is that the balls collide with each other, causing extra friction.But you can prevent this by putting the ball in a small cage.In the 17th century, Galileo made the earliest description of "caged ball" ball bearings.At the end of the 17th century, the ball bearings were designed and manufactured by c. wallow in England and tested on mail wagons, and patented by p. worth in England.The first practical rolling bearing with a cage was invented in 1760 by clockmaker John harrison for the H3 chronograph.In the late 18th century, H.R. Hertz of Germany published a paper on contact stress of ball bearings.On the basis of Hertz's achievement, r. striebeck of Germany, a. palmgren of Sweden and others have carried out A large number of experiments, which have contributed to the development of the design theory and fatigue life calculation of rolling bearings.Later, N.P. petrov of Russia applied Newton's law of viscosity to calculate bearing friction.The first patent for the raceway was granted by Philip vaughn of carmarthen in 1794.
In 1883, friedrich fischer laid the foundation for the bearing industry by proposing the use of suitable production machines to grind steel balls of the same size and precise roundness.The British o. Reynolds made a mathematical analysis of toll's discovery and derived the Reynolds equation, which laid the foundation of hydrodynamic lubrication theory.
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.
To identify the quality of equipment bearings, we usually carry out from the following aspects:
1. Whether the outer packing is clear or not
Under general circumstances, the brand that normal manufacturer produces has oneself special designer to undertake design to pack outside, and arrange the factory that produces a condition to pass to make production, accordingly, the package of product no matter from line to color block should be very clear, without ambiguity.
2, whether the stencil is clear
Each bearing product will be printed on the bearing product body its brand name, label, etc.Although the font is very small, but the formal manufacturers of the products are using the stenciling technology to print, and in the process of pressing before not overheating, so its font is small, but deep concave, very clear.And in general, the counterfeit product font is not only fuzzy, due to the printing technology is rough, fonts float on the surface, some can even be easily wiped with the hand or manual traces of serious.
3. Is there any noise
The left hand holds the bearing body sleeve, and the right hand reciprocates the jacket in a small amplitude to make it rotate, listen to whether there is noise during the bearing operation.Due to the backward production conditions of most counterfeit products and manual workshop operation, the bearing body will inevitably be mixed with dust, sand and other impurities in the production process, so when the bearing rotation will appear noise or not smooth operation.This is the key to determining whether a product is a branded product from a legitimate manufacturer with strict production standards and machine operation.
4, the surface
Whether there is a muddy oil trace on the surface requires us to pay special attention when buying imported bearings.Because of the domestic antirust technology and foreign advanced manufacturing countries have a certain gap, so the bearing body antirust treatment is easy to leave a thick trace of oil, feel sticky when the hand contact, and foreign original imported bearings almost no trace of antirust oil can be seen.According to the introduction of the industry, special careful people can smell a special smell on the imported bearings, this is the smell of rust prevention oil.
5. Whether the chamfering is uniform
The chamfering of the so-called bearing, that is, the intersection between the horizontal and vertical surfaces, the counterfeit bearing products due to the limitations of production technology, in these corners of the parts are not satisfactory, this we can easily identify.
6, the packing
Bearing packing includes inner packing and outer packing
After the bearings are manufactured and passed the inspection, they shall be cleaned and rust-proof, and then put into the inner packaging to achieve the purpose of water-proof, moisture-proof, dustproof, shock-proof, maintenance of the quality and accuracy of the bearings, as well as convenient use and sales.
The bearing inner packaging is divided into three categories according to the anti-rust period:
(1) short rustproof period packaging: rustproof period of 3 ~ 6 months, suitable for mass shipment to the same subscriber, in a short time will be put into use bearings.By agreement of both parties, in order to facilitate the use of the principle, the use of simple packaging.
(2) general antirust packaging: antirust period of one year, suitable for general purpose bearings.
(3) long antirust period packaging: antirust period of two years, suitable for special and precision bearings.
The inner packing materials of bearing include polyethylene plastic drum (box), kraft paper, plain and corrugated polyethylene composite paper, paper box, polyethylene or polyethylene plastic film, nylon fastening belt or plastic woven fastening belt, waterproof high-strength plastic belt, gunny bag, etc.All the above materials should be qualified in corrosion resistance test.