The national standard
1.National standard for vibration acceleration (commonly known as Z standard)
This standard was established earlier, to measure the vibration acceleration value of the bearing when rotating, to determine the quality of the bearing, divided into Z1, Z2, Z3 from low to high three quality grades.At present, domestic bearing manufacturers are still in use. The vibration acceleration value is used to measure the strength of the bearing, which simply reflects the fatigue life of the bearing.
2.Vibration speed standard (commonly known as V scale)
Because the original vibration acceleration standard has not been abolished, so the standard is issued by the ministry of mechanical industry standards, is a reference to the European standard combined with the actual situation of China and the need to develop, to test the vibration speed of bearing to classify the quality level of bearing (equivalent to the national standard).It is divided into V, V1, V2, V3 and V4.The quality grades of various ball bearings are V, V1, V2, V3, V4 from low to high;Roller bearing (cylinder, cone) quality grades from low to high for V, V1, V2, V3 four quality grades.
It reflects the quality of the bearing by detecting the vibration b velocity of different frequency segments (low frequency, medium frequency, high frequency) of the bearing.It can be generally analyzed whether the bearing has the problem of geometric size (such as the ellipse of the steel ring), the quality of the raceway/roller, and the quality of the retainer.At present, bearings exported to Europe, China's military and aerospace industry all carry out quality testing in accordance with this standard. Meanwhile, it provides a feasible means to test the quality of bearings imported from Europe and distinguish fake imported bearings.
Bearing quality testing has two standards in parallel situation, and "Z standard" of high quality level bearings, "V standard" may not have good quality performance, there is no correspondence between the two.This should be paid special attention to in the quality test of bearing.
To identify the quality of equipment bearing, we usually proceed from the following aspects:
1. Whether the outer packing is clear
Double row tapered roller bearing
Double row tapered roller bearing
Under normal circumstances, regular manufacturers have their own special designers to design the external packaging, and arrange the production conditions of the factory to make production, therefore, the product packaging from the line to the color block should be very clear, without ambiguity.
2. Whether the stenciled words are clear or not
Each bearing product will be stamped with its brand name, label, etc.Although the font is very small, but the products produced by the regular manufacturers have used the stencil printing technology to print words, and before the treatment of overheating on the press, so the font although small, but deep, very clear.Usually, the typeface of the counterfeit product is not only blurred, but also floats on the surface due to the rough printing technology, some of which can be easily erased by hand or serious manual marks.
3. Is there any noise
The left hand holds the inner cover of the bearing, and the right hand reciprocates by pulling the coat in a small amplitude to make it rotate.Because the production conditions of most of the counterfeit products are backward, completely manual workshop operation, in the production process, the bearing body will inevitably be mixed with dust, sand and other impurities, so in the rotation of the bearing will appear noise or run not smooth phenomenon.This is the key to determining whether a product is produced under the brand name of a regular manufacturer with strict manufacturing standards and machine operation.
4, the surface
Whether there is a muddy oil mark on the surface requires us to pay special attention when buying imported bearings.Due to the domestic antirust technology and foreign advanced manufacturing countries still have a certain gap, so the bearing body antirust treatment is easy to leave a thick oil mark, touch with the hand feel sticky thick, and foreign imported bearing almost can not see any traces of antirust oil.According to the introduction of the industry, especially careful people can smell a special flavor in the import bearing, this is the smell of anti-rust oil.
5. Is the chamfering uniform
The so-called bearing chamfering, that is, the intersection of horizontal and vertical surfaces, counterfeit bearing products due to the limitations of production technology, in these corner parts of the processing is not satisfactory, this we can easily identify.
6, the packing
Bearing packing includes inner packing and outer packing
After the bearing has been manufactured and passed the inspection, it shall be cleaned and rust-proof, and then put into the inner package to achieve the purpose of waterproof, moisture-proof, dustproof, shock-proof, quality and precision maintenance of the bearing, as well as convenient use and sale.
The inner packing of bearing is divided into three categories according to the rust prevention period:
Short anti-rust period packaging: the anti-rust period of 3 to 6 months, suitable for mass delivery to the same subscriber, will be put into use within a short period of time.As agreed by both parties, simple packing is adopted in the principle of ease of use.
General anti-rust packaging: anti-rust period of one year, suitable for general purpose bearings.
Long antirust packaging: antirust period of two years, suitable for special and precision bearings.
The inner packing materials of the bearing are polythene plastic tube (box), kraft paper, plain and furrow polythene composite paper, paper box, polythene or polythene plastic film, nylon fastening belt or plastic woven fastening belt, waterproof high-strength plastic belt, gunny bag, etc.The above materials shall be qualified for corrosion resistance test.