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/*728*90 created on 2018/5/16*/ var cpro_id = "u3440131"; Home>Bearing knowledge>High-speed bearing device cooperation and adjustment High-speed bearing device cooperation and adjustment
1. High-speed bearing cooperation and clearance Because high-speed bearings need to be based on high-precision bearing requirements; and high-temperature NSK bearing requirements; so when considering their cooperation and clearance; consider the following two points: /*250*250 was created on 2017/12/25*/ var cpro_id = 'u3171089';
(1) Scale changes and hardness changes from normal temperature to high temperature, (2) Force changes and shape changes caused by centrifugal force at high speed.
In the high-speed, high-temperature conditions; from the cooperation and clearance selection to strive to adhere to the accuracy and operation of NSK bearings; this is difficult.
In order to ensure the deformation of the raceway behind the bearing device, the tomb is ridiculously ridiculously 螅 螅 螅 螅 螅 螅 螅 螅 螅 螅 螅 螅 螅 螅 螅 蛘 蛘 蛘 蛘 蛘 蛘 蛘The cooperation is lax; therefore, the excess amount needs to be carefully calculated under the premise of thinking about the above two factors; the useful interference at normal temperature and normal speed may be invalid for high-speed bearings.
If the result of the calculation is too large (usually as long as it is under ultra-high speed); as long as the two-layer smooth method of the under-smooth smoothing method and the static-pressure smoothing method is adopted; and such a plan may make the dmn value of the bearing Break the 3 million mark.
When thinking about the high-speed NSK bearing clearance, not only must consider the above factors; but also consider the influence of the thermal elongation of the shaft on the clearance; the bearing needs to be in the working condition; that is, the optimal clearance at the working temperature; This kind of clearance is formed under the condition of accurate alignment between the inner and outer ring grooves. Because the high-speed bearing strives to reduce the relative sliding and internal conflict; the best way is to use the inner and outer rings to be axially misaligned. Adjust the clearance of the ball bearing.
When thinking about the cooperative interference and clearance of the bearing; pay attention to the characteristics that the data becomes soft and simple deformation at high temperature; and the temperature change from normal temperature to high temperature repeatedly leads to the possibility of permanent eternal deformation.
2. Demand for mainframe-related parts High-speed bearing requirements Bearing reversal system through fine dynamic balance; shaft and seat hole bearing parts should have higher than the usual requirements of dimensional accuracy and shape accuracy; especially coaxiality and shoulder Straightness of the seat hole or journal; while considering the time of these problems; it is necessary to pay attention to the high-speed elements and high-temperature elements of the bearing operation.
The shaft support system requires both high rigidity and the required quality as light as possible; in order to overcome this opposition; it can adopt methods such as reducing the appearance roughness and improving the appearance reinforcement to improve the support stiffness; using the hollow shaft to reduce the system quality.
3. The development example of ultra-high speed bearings is based on the development of ultra-high speed HA tapered roller bearings.
(1) The problem is raised in gas turbines and some machine tools and engineering machinery; high speed and axial load; the use of ball bearings is too short; the use of short cylindrical roller bearings is lack of axial load; axial clearance Difficult to adjust; expect to use tapered roller bearings to break this problem.
(2) Skills that need to be dealt with. The skill of high-speed restraint of tapered roller bearings is to improve the smoothness between the large ribs of the inner ring and the large end faces of the rollers; this part is most prone to severe wear and burn at high speed; The main reason for constraining its speed.
(3) Treatment method In the general layout of tapered roller bearings; smooth oil flow path is difficult to obtain smooth oil in the inner ring large rib and the large end face of the roller; this part is relatively large sliding; it is the most demanding smooth oil.
Therefore, Japan and other countries have developed HA-type tapered roller bearings; this bearing rib is on the outer ring; this smooth oil can smooth the outer ring rim and the touch surface of the roller's large end face; together here even when stopped It can also store some oil; it prevents the oil from burning when starting; but there are several oil drain holes on the outer ring ribs according to the demand; to prevent the oil from discharging the passage; the power loss and temperature of the oil mixture formed in a certain part Raise too high. Because the inner ring has no ribs; the temperature has dropped; therefore, the possibility of seizure activity between the inner ring and the shaft is reduced. This type of bearing supports the outer ring guiding method for the support frame; The frame can guide the roller to work smoothly without tilting; prevent seizure and excessive wear; this is also beneficial to high speed.
(4) Achievable function The HA-type bearing has a dmn value of up to 2 million; twice the advancement of the general layout; for example, for a gas turbine reducer main shaft (model I-IA30205); Under the condition of 1000N load; ensure that there is 2L/min oil supply to the bearing to supply circulating No. 4 turbine oil; its working speed can reach 60,000 revolutions without causing burns.
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Source: China Bearing Network Time: 2017-12-22