How to accept the bearing, what qualifications are required for bearing acceptance

Generally speaking, if you really use a machine to measure, it requires a complex machine.

Whether the outer packaging is clear.

Under normal circumstances, the brands produced by regular manufacturers have their own special designers to design the external packaging, and arrange the production conditions of the factory to produce and produce, therefore, the packaging of the product should be very clear and unambiguous from the lines to the color block.

Whether the stamping is legible.

Each bearing product will be printed with its brand words, labels, etc. on the bearing product body. Although the font is very small, the products produced by regular manufacturers are printed with steel printing technology, and the font is pressed before heat treatment, so although the font is small, it is deep and very clear. Normally, the font of counterfeit products is not only blurry, but also floating on the surface due to the rough printing technology, and some can even be easily erased by hand or have serious manual marks.

Whether there is a noise or not.

Hold the inner sleeve of the bearing with your left hand, and rotate the outer sleeve with your right hand to listen to whether there is any noise during the operation of the bearing. Due to the backward production conditions of most counterfeit products and the complete manual workshop operation, it is inevitable that impurities such as dust and sand will be mixed into the bearing body during the production process, so there will be noise or poor operation when the bearing rotates. This point is the key to judge whether a product comes from a brand product of a regular maker which has a strict production standard and operates with a machine.

Whether there are cloudy oil stains on the surface.

Whether there are turbid oil stains on the surface, which requires us to pay special attention when buying imported bearings. Because there is still a certain gap between the current anti-rust technology in China and the advanced manufacturing countries abroad, it is easy to leave thick oil stains when the bearing body is treated with anti-rust, and it feels viscous and thick when touched by hand, while there is almost no trace of anti-rust oil on the bearings imported from abroad. According to industry insiders, particularly careful people can smell a special smell on imported bearings, which is the smell of anti-rust oil.

Whether the chamfer is uniform.

The so-called chamfer of the bearing, that is, the junction of the horizontal plane and the vertical surface, the counterfeit bearing products due to the limitations of production technology, in these corners and corners of the parts are not satisfactory, which we can easily identify.

According to the dimensional accuracy and rotation accuracy to accept, there are special instruments. In addition, there is a look at the appearance and the like.

Whether the identification and accuracy level on the outer packaging are consistent with the products in the package, each package of products must be accompanied by a quality certificate. The certificate should indicate the name of the manufacturer, bearing code, standard code, and the date of packaging. 2. Each set of bearings must have a permanent manufacturer's code and bearing model mark, and the content of the mark should be complete and clear, and consistent with the content on the certificate.

3. When replacing the bearing, the contact angle between the journal and the lower bearing is 60 900 seal, the contact area should be uniform, and the contact point is not less than 2 3 points per square centimeter of Pingshan Shidong. 4. Observe the bearing with the naked eye, and there should be no peeling marks and wear; The surface of all rolling elements should be free of spots, cracks and bumps; The rolling element clearance should fit closely and rotate flexibly. 5. The rolling element and oil of the bearing and the surface of the slideway should be free of corrosion, pit scars and spots, and the contact should be smooth and noiseless.

(1) Observational method. Observe the rolling bearing with the naked eye, the inner and outer raceways should have no peeling marks and serious wear, and be in the shape of an arc groove; All rolling elements should be free of spots, cracks and peeling on the surface; The cage should not be loose, undamaged, unworn through, and the gap between it and the rolling elements should not be too large.

2) Hand feel method. The clearance between the inner and outer racepieces and the rolling elements of a normal bearing is millimeters. For rolling bearings that have been used for one stage, there should be no obvious noise when pinching the inner seat ring with your fingers for axial rocking.

3) Rotation method. Clamp the inner racer with one hand and rotate the outer racer with the other, the bearing should be able to rotate flexibly and radial shaking should not be felt.

During the inspection, the above three empirical methods should be combined to facilitate the correct judgment of the technical status of the rolling bearing. For tapered roller bearings, it should also be observed that the rolling elements are located in the middle of the outer race, and if there is a forward movement, it should not exceed millimeters.

1) Width standard parts.

The width standard room is used to check the width of the inner and outer rings of the bearing. The width standard parts are used in conjunction with the G903 series gauges and gauges to measure the width of the ferrule. The working surface of the standard parts is not allowed to have bruises, burrs, etc.

If there are bruises and burrs on the working surface, it needs to be re-identified to avoid measurement errors. Guess the song.

2) Inner diameter and outer diameter standard parts.

The inner diameter and outer diameter standard parts are used to check the inner diameter size and outer diameter size of the bearing respectively. The inner diameter and outer diameter of the bearing are the main dimensions of the bearing, and it is one of the important items that determine the quality of the bearing, so the verification of the inner diameter and the outer diameter of the standard parts must be accurate.

The inner diameter standard parts are matched with the D923 series inner diameter measurement and instrument. It can measure the inner diameter size, the inner diameter change of the inner diameter in a single meridional plane, and the runout of the inner ring reference end to the inner diameter. The outer diameter standard parts are matched with the D913 series outer diameter measurement and instrument, which can measure the outer diameter size, the change of the outer diameter in a single plane, and the change of the inclination of the outer diameter surface bus to the reference end face.

3) Groove diameter standard tassel Ming Zheng Zhun piece.

The inner groove diameter and the outer groove diameter standard parts are used to inspect the groove diameter of the inner ring and the outer ring of the bearing respectively, and the parts selected from the product must be qualified for the groove diameter, groove curvature, groove symmetry, and the groove diameter change in a single radial plane. The channel standard parts are divided into inner and outer ditch standard parts. The standard parts of the inner channel are used to measure the diameter of the inner ring channel, the change of the inner channel diameter in a single radial plane, etc.

The standard parts of the outer channel are used to measure the diameter of the outer ring channel, the diameter of the inner and outer channel in a single horizontal plane, etc.

4) Clearance and vibration standard parts.

Gaming and vibration standard parts are used to check the clearance and vibration of the bearing, respectively, and are selected from the product. The clearance standard parts are combined with the X092 series radial clearance measuring instrument and instrument to measure the radial clearance of the bearing. The vibration standard is used in conjunction with the S0910 or BVT-1 vibration measuring instrument to measure the vibration acceleration (or velocity) level of the bearing.

Problems that should be paid attention to when using standard parts.

a.Standard parts have certain technical requirements, such as nominal dimensions. and actual deviation, geometric accuracy, position accuracy, hardness, appearance (including surface roughness and surface defects) so it must be handled with care in use to prevent bumps.

After use, wash and wipe it in time and put it in the designated position.

This is based on the vibration standard for bearing quality testing.

There are the following two standards: the national standard for vibration acceleration (commonly known as the Z standard) and the vibration speed standard (commonly known as the V standard).

Yangzhou Fuenqi said: the bearing in operation can generally be manifested as a significant increase in acceleration, with the development of fatigue, the gradual increase in vibration speed and displacement, indicating that the bearing has fatigue failure. Especially for the bearing detection, pay careful attention to whether the vibration value is unstable swing (it is recommended to use analog pointer instruments, which can be observed very obviously), if there is swing, it indicates that there is an unstable vibration signal, and the acceleration is also large, especially the speed increases at the same time, and it is very likely that there is a bearing "trick" failure.

For new equipment, when testing and accepting, although the vibration is very small, in line with the national standard, but there is a small amplitude of vibration swing phenomenon in the bearing part, after excluding the bearing fit problem, it is very likely that there is a problem with the geometric size of the bearing, such as the bearing steel ring ellipse, when the rolling element passes through the position of the elliptical long axis, the rolling element may be instantly stuck due to the reduction of the gap, and the subsequent rolling element continues to squeeze, so that the rolling element produces sliding friction, and each rolling element will have sliding friction here, resulting in an unstable signal. Special tip: When inspecting rolling bearings, be sure not to ignore changes in bearing acceleration values.

The diameter and outer diameter of the bearing, as well as the grinding of the rolling fork, whether there is any obstruction.

How to inspect the appearance of bearings.

The key points to pay attention to in the visual inspection are as follows:

1) All kinds of cracks, such as raw material cracks, forging cracks, heat treatment cracks and grinding cracks, etc., these cracks will become a source of stress concentration and expand rapidly during the operation of the bearing in the future, resulting in bearing rupture, which has a great impact on bearing life and work safety. In fact, for bearings for critical applications, bearing factories have carried out 100 magnetic or radiographic flaw tests on their constituent parts.

2) All kinds of mechanical scars, such as abrasion, scratches, crushes, bumps, etc., will cause poor bearing installation, cause eccentric load and stress concentration, and cause the decline of rotation accuracy and service life.

3) Rust, black skin and pitting, the latter two are defects that easily store moisture and dirt, and are the most likely to develop into rust. Corrosion, on the other hand, is a source of contamination that leads to poor installation, early wear and fatigue, and severe corrosion can lead to the scrapping of bearings.

4) Peeling and folding, the local combination of these two defects with the base metal is not firm, and there are often decarburization or carbon depletion phenomena around it to varying degrees, and the material is easy to collapse, concave or wear, which is very unfavorable to the bearing life and accuracy.

5) The riveting or welding quality of the cage is mainly observed whether the rivet head is offset, skewed, relaxed, lack of meat or "double eyelids", whether the welding position is correct, whether the welding joint is too large or too small, whether the welding is not firm or the welding is too large and causes the phenomenon of stuck rolling elements, whether the quality of the slope and edge of some cages, the quality of the joints and chisels is guaranteed, whether the rolling elements can not fall out of the cage and can return, such as, if these points do not meet the requirements, the small will cause the bearing noise and rotation accuracy to be reduced, and the large may cause the cage to fall apart, Causing mechanical breakdowns or accidents.

If the above items from (1) to (5) are found during the inspection, the bearing will also not be accepted. In addition, if the typing quality is poor, such as blurred handwriting and damage, it should be regarded as defective, and serious cases can also not be accepted.