Waviness and Noise of Tapered Roller Bearings

Time：2020.08.31  Source：Roller Bearings Suppliers

Reducing bearing noise is an urgent problem to be solved in the bearing industry in improving bearing quality. The main factor affecting the noise of tapered roller bearings is the waviness of the bearing groove surface and the surface of the steel ball. Waviness is caused by vibration in the grinding process, so it is necessary to study the relationship between vibration and skin texture and the cause of vibration.

The relationship between vibration and waviness

There are many reasons that affect the waviness, which mainly depends on the vibration during the grinding process. The greater the vibration force, the greater the amplitude. As the amplitude increases, the waviness value of the waviness also increases, and the waviness value is proportional to the amplitude of the vibrating body.

Causes and elimination of vibration

In the grinding process, the grinder mainly produces forced vibration, self-excited vibration and free vibration. Forced vibration accounts for more than 60%, self-excited vibration accounts for about 30%, and the rest is free vibration.

1. Forced vibration

There are many reasons for forced vibration, but the vibration frequency caused by forced vibration is often equal to or doubled as the frequency of the vibrating body itself, so it is easy to find the source of the vibration and eliminate it.

(1) Caused by imbalance of the grinding wheel

a. The grinding wheel should be statically balanced once before rough repairing, and then statically balanced again after rough repairing, and then finishing the grinding wheel. WSBC 22224 CC/W33 is our main products , if you need , pls click here to learn more : 

b. When installing the grinding wheel, make sure that the flange of the grinding wheel is perpendicular to the cone hole, so that the cone hole and the cone surface of the spindle are in good contact. balance.

c. After stopping grinding and turning off the coolant, keep the grinding wheel idling for 5-7 minutes, and remove the extra coolant on the grinding wheel by centrifugal force. Otherwise, after the machine tool stops for a certain period of time, the extra coolant will be solidified in the lower part of the grinding wheel. When the machine tool is restarted, the grinding wheel will be out of balance.

d. Because the internal organization of the grinding wheel is uneven, even if the original balanced grinding wheel is used, a new imbalance will occur during use, so it is best to use an automatic balancing device during the grinding process.

(2) Due to the difference in the internal bonding strength of the grinding wheel

In the grinding process of the grinding wheel, the bonding strength is different, and the speed at which the abrasive particles fall off is also different. The part with high bonding strength of the grinding wheel is not easy to fall off, and the production area is locally passivated. The grinding wheel itself naturally forms a corrugated state, which can also cause vibration during the grinding process.

(3) Influenced by motor vibration

a. Unbalanced rotating parts such as the rotor and pulley of the motor can also cause vibration, so the dynamic balance must be carefully balanced. It is best to reduce the amplitude of the motor to about 5μ.

b. The motor that has taken measures still vibrates. Therefore, use hard rubber or vibration absorbing device to isolate it at the machine installation.

2. Self-excited vibration

Self-excited vibration is caused by the grinding process itself. The principle of the self-excited vibration process during grinding, a periodic alternating grinding force component P produced during unstable grinding, which acts on the machine tool system and causes vibration Y, and Y in turn Affect the alternating force P. The interaction between the two basic parts makes the resulting vibration very complicated. WSBC 22224 CCK/W33 is our main products , if you need , pls click here to learn more :

The waviness is also related to the selection of process specifications. When the feed speed of the grinding wheel holder increases, the grinding resistance will increase, and the amplitude of the grinding wheel shaft will increase, resulting in an increase in the waviness value. The waviness is not only determined by the amplitude of the grinding wheel shaft, but also related to the nature of the grinding wheel, the bonding strength and the quality of the grinding wheel correction. Because the change of the grinding wheel surface will cause the change of the grinding resistance, which has an effect on the waviness.

In short, forced vibration always exists, and the key is how to find the source of the vibration to reduce the vibration. Self-excited vibration is the opposite of forced vibration. This vibration either does not occur at all (stable grinding); or it occurs and quickly increases the amplitude (unstable grinding). Therefore, process departments and operators must create conditions to prevent self-excited vibration or minimize self-excited vibration.