Bearing structure on vibration and noise
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| Time：2016.08.27 News Sources：Shandong Xinkaite bearing Co.,Ltd. Views：
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1. raceway sound
Raceway sound is due to the rotation of the rolling element bearing raceways and rolling inspire in a smooth and continuous noise, the level or tone when great draw attention only when. In fact raceway sound inspired by the acoustic energy is limited, as under normal circumstances, the quality of 6203 bearing raceway sound is 25 ~ 27dB. This noise is to bear radial load single row deep groove ball bearing is the most typical, it has the following characteristics:
. A noise and vibration is random;
. B vibration frequencies above 1kHz;
. C irrespective of speed changes, the main frequency noise is almost constant and the sound pressure level increases with the speed increase;
. D When the radial clearance increases, the sound pressure level increased dramatically;
. E bearing rigidity increases, the lower the total sound pressure level, even if the speed increases, the total sound pressure level increases is not;
f. The higher the viscosity of the lubricant, the lower the sound pressure level, but for grease lubrication viscosity, soap fiber shape and size can affect the noise level.
Raceway sound generated by the source that the ring after the natural vibration loads due. Since the resilient contact rings and rolling elements constituting the nonlinear vibration system. When lubricating or processing accuracy is not high, it will stimulate the natural vibration of the elastic characteristics related to the transfer of noise into the air. As we all know, even with the highest levels of modern manufacturing technology and processing bearing parts, the tiny geometric errors in its work surface will always exist varying degrees, so that the generated between the rolling elements and raceway small fluctuations in the excitation vibration system natural vibration. Although it is inevitable, however, can take high-precision machining parts work surface, use the correct selection of bearings and precision bearings make noise damping.
2. Scroll the sound of a falling body
The noise is generally the case, most occur at low speeds and large radial load bearing. When the bearing radial load operation, the load bearing and non-load zone area, if the bearing has a radial clearance, the non-load bearing rolling elements and the inner region of the raceway is not in contact, but the centrifugal force may be associated with the outer circle contact this end, at low speeds, when the centrifugal force is less than the weight of the rolling elements, the rolling elements and the inner raceway and fall or collision and excitation cage bearing the inherent vibration and noise, and has the following characteristics:
a. grease lubrication is easy to produce, easy to produce oil lubrication. When more likely to have low quality grease.
b. winter often occur.
c. For only the role of radial load and radial clearance is large also easy to produce.
d. will produce within a certain range and bearing its speed range of different sizes are also different.
e. may also be a continuous sound may be intermittent sound.
f. This often forced vibration excitation of second order outer ring, third bending natural vibration, thus the issue of the noise. By using preload method can effectively reduce the noise, reduce installed after the bearing radial clearance, a good selection of the lubricant can also be improved, some foreign companies use light rolling elements, such as rollers or ceramic hollow roller and other technical measures this prevents the generation of noise.
3. pointed song
It is the sliding friction between the metal quite violent screams, although this time the bearing temperature is not high, but also without much influence on bearing life and grease life, does not affect the rotation, but unpleasant sound disturbing, especially large radial load of cylindrical roller bearings often this noise, which is characterized by:
a. bearing radial clearance is large and easy to produce.
b. usually appears in grease lubrication, oil lubrication is relatively rare.
c. With the bearing size decreases, and often occurs within a certain speed range.
d. often occur in winter.
e. Its appearance is irregular, and unpredictable and filled with fat content and performance, installation operating conditions. This noise can reduce the radial bearing clearance and the use of shallow structure to prevent the outer ring raceway.
4. The holder sound
Remain free vibration frame and it rings or rolling elements collide will send this noise in the bearing during rotation. It can occur in all kinds of bearings, but the sound pressure level is not too high and low frequencies. Its characteristics are:
a. stamping cage and plastic cage can produce.
b. Whether thin oil or grease will appear.
c. When the outer ring bending moments most likely to occur.
d. prone to large radial clearance.
Since the cage pockets and the cage with the gap in the bearing ring gap finished inevitable to exist, so the total elimination of cage sound very difficult, but by reducing assembly errors, preferably a reasonable gap and cage runout to improve .
Another special cage sound is noisy sound due cage and other parts of the guide bearing surface between the friction caused by the holder of the self-excited vibration occurs. Deep groove ball bearing cage stamping thin, low bending stiffness in the radial and axial plane, the overall stability of the poor, will be due to bending deformation of the self-excited vibration during high-speed rotation of the bearing, causing the "beep" .
When the bearing radial loads and poor performance of the grease, the initial operation will hear the "click, click" noise, which is mainly due to the rolling elements in the load zone after leaving the rolling elements and the cage sudden acceleration phase collision noise issued, but with such a crash is inevitable after a period of operation will disappear.
Prevent cage noise measures are as follows:
a. In order to stabilize the orbital motion of the cage, should be used to guide the ferrule way and give full attention to lubricate the guide surface of the bearing structure of the high-speed condition to give improved the L-shaped roller guide to the ferrule holder Z-type guide rib cage.
b. When the high-speed rotation bearings, bearing a large pocket gap vibration amplitude is much larger than its cage pocket clearance small cage vibration amplitude, so the pocket gap values is particularly important.
c. To pay attention to minimize the radial clearance.
d. Try to improve manufacturing precision cage, the cage to improve the surface quality, help reduce the rolling elements and the cage collision or friction noise.
e. active use of advanced cleaning technology, spare parts Hop sets after thorough cleaning product effectively, improve the cleanliness of the bearing.
5. Scroll through the body vibration
When the bearing radial load operation, only the number of its internal load bearing rolling elements, "spring" the rolling body supporting resilient contact with the ferrule due to the configuration of the periodic vibration generated by radial load line, Therefore, the meeting center axis vertical movement or do horizontal direction, and lead to noise. Such vibration is called rolling elements by vibration, especially more obvious at low speed.
The amplitude and the bearing type, radial load, radial clearance and the number of rolling elements related. Usually the smaller amplitude, if amplitude is large when forming harm, for this is often used to reduce the radial clearance or applying an appropriate preload to reduce.
Effect of temperature on bearing life
Bearing in the work, due to its size and change the structure of the material changes. This shift by temperature, time and stress influence.
In order to avoid the structure of the material changes and dimensional changes are not allowed at work, bearing materials must undergo a special heat treatment.
Depending on the bearing type, standard bearings is quenching and induction hardening heat treatment of steel with a recommended maximum operating temperature between 120-200 degrees. Can reach a maximum operating temperature of the heat treatment process has a direct relationship. If an applications normal operating temperature higher than the recommended maximum temperature stability should be used in high series bearings. If the bearings need continuous operation at high temperatures, dynamic load bearing capacity may need to make adjustments.
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