Detecting the quality of INA bearing lubricants from the noise used in lubrication

The three simplest detection methods for lubricating oil are: oil spot method, color discrimination method and honing method.

Oil spot method:

The oil to be inspected is evenly mixed and dropped on a white paper (preferably a filter paper) to form oil spots, and the oil spots gradually diffuse from the center outward for about 2 to 3 hours to form three concentric rings. The state of the oil can be discerned based on the color, width and shape of the three areas.

Color discrimination method:

Normal is brown and blue black. If it is milky yellow, it indicates that diesel oil or water is added to the oil and should be replaced in time. If it is dark black, it indicates that the oil has deteriorated and must be replaced in time.

Honing method:

Remove a little oil from the low shell of the oil, apply it on your fingers, and rub it with your fingers and thumb. If you feel that there is impurities in the oil or that it is not sticky like water, or even hairy or sour, the oil has deteriorated. If you can see a small shiny metal grinding on your finger after honing, it means that the engine has a serious wear part, and it also means that the oil must be replaced immediately.

1. Low temperature high speed bearing grease

At present, the equipment using INA bearings is becoming more and more refined, and the grease used for bearings must have the following properties:

(1) It has the same operating life as the bearing, prolongs the maintenance cycle, shortens downtime and improves labor productivity.

(2) Under the high speed of dn>5×105, it is necessary to ensure that the motor temperature rises low and does not lick oil, thus reducing power consumption and protecting the motor.

(3) The impurity content is controlled under certain standards to minimize the pollution of equipment noise to the environment.

(4) Guarantee the flexibility of starting and running the bearing under ultra-low temperature working conditions to ensure the minimum output power.

2. General low noise motor bearing grease

In the INA bearing industry, this grease is used in the largest amount, accounting for about 70% of the total grease. Because this type of grease uses a soft, easy-to-filter lithium soap as a thickening agent, using mineral oil as a base oil, it is easy to meet the requirements of low and medium-end bearings to reduce the vibration value. Another advantage is that it has good pumpability, whether it is mechanical fatliquoring or manual grease application.

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Five precautions for the use of imported bearings, five ways to avoid failure

Precautions for use

Rolling bearings make precision parts, so they need to be cautious when using them. They use high-performance imported bearings. If they are not used properly, they can not achieve the expected performance. Therefore, the following items should be used when using bearings:

Keep the bearings and their surroundings clean. Even if the smiling dust that is invisible to the naked eye enters the bearing, it will increase the wear, vibration and noise of the bearing.

Care must be taken when using the installation. Strong stamping is not allowed. It is not allowed to directly hit the bearing with a hammer. It is not allowed to transmit pressure through the rolling elements.

Use suitable and accurate installation tools, try to use special tools, and try to avoid the use of cloth and short fibers.

To prevent the corrosion of imported bearings, when taking the bearing directly by hand, wash the sweat on the hand and apply it with high-quality mineral oil before handling. In the rainy season and summer, pay special attention to rust prevention.

Bearing cooperation

Matching choice

The inner and outer diameters of the rolling bearing are manufactured to standard tolerances. The tightness of the bearing inner ring to the shaft and the outer ring to the seat hole can only be achieved by controlling the tolerance of the journal and the tolerance of the seat hole. The inner ring of the bearing and the shaft are matched by a base hole, and the outer ring of the bearing and the seat hole are made by a shaft.

The correct choice of cooperation must be aware of the actual load conditions, operating temperatures and other requirements of the imported bearings, but it is actually very difficult. Therefore, most of the cases are based on the use of lint selection.

Load size

The amount of over-win between the ferrule and the shaft or casing depends on the size of the load. The heavier load uses a larger over-win, and the lighter load uses a smaller over-win.

1. Bearing channel one-side extreme position peeling

The one-side extreme position spalling of the channel is mainly manifested by a severe spalling band at the interface between the channel and the rib. The cause is that the imported bearings are not installed properly or there is a sudden axial overload during operation. The countermeasure is to ensure that the bearing is installed in place or the free side bearing outer ring is matched to the clearance fit, so that the bearing is compensated when the bearing is overloaded.

2. The bearing channel peels off symmetrically in the circumferential direction

The symmetrical position spalling shows that the inner ring is spalled around the inner ring, and the outer ring is peeled off in a circumferentially symmetric position (ie, the short axis direction of the ellipse). The reason for this is mainly because the outer hole of the outer shell is too large or the two half are separated. This is particularly evident in camshaft bearings for motorcycles. When the bearing is pressed into the outer shell hole of the elliptical ellipse or the two halves of the split outer casing are fastened, the outer ring of the bearing is made elliptical, and the play in the short axis direction is significantly reduced or even negative. Under the action of the load, the inner ring rotates to produce circumferential peeling marks, and the outer ring only produces peeling marks at the symmetrical position in the short axis direction. This is the main reason for the early failure of the bearing. After testing the failure of the bearing, the roundness of the outer diameter of the bearing has been changed from 0.8μm to 27μm. This value is much larger than the radial clearance value. Therefore, it can be confirmed that the bearing is working under severe deformation and negative play, and it is easy to form abnormal sharp wear and peeling at the early stage. The countermeasures taken are to improve the machining accuracy of the outer casing hole or to use the two-half separation structure of the outer casing hole as much as possible.

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