A supporting side structure
In order to ensure the normal pass of the rolling bearing shaft axial force and does not occur ran axis part positioning fixed on the basis of the rational design of the fixed axial structure of the shaft fulcrum. There are three types of typical structure.
(1). Both ends of a one-way fixed
The short axis of the normal operating temperature (span L <400mm), the fulcrum often both ends of a one-way fixed, each bearing, respectively, under the direction of the axial force. Figure 17-15. To allow the shaft work a small amount of thermal expansion, bearing installation should be left 0.25mm-0.4mm axial gap (the gap is very small, do not have to draw on the chart), commonly used gasket or adjustment screw to adjust the gap amount.
(2). End of the two-way fixed end of the swimming
When the axis is longer or higher operating temperature axis thermal expansion and contraction should be the end of the two-way fixed fulcrum end of the swimming structure. Fixed terminus of a single bearing or bearings to withstand the bidirectional axial force, swimming side to ensure that the axis stretching can swim freely. To avoid loose, swimming in the bearing inner ring and shaft axially fixed (often elastic ring). For swimming fulcrum with cylindrical roller bearings, the bearing outer ring and the base unit for axial fixation by swimming between the roller and the ring to ensure that the axis of free expansion.
(3) both ends of the swimming
Requirements can be bi-directional swimming around the axis, can be used at both ends of the shaft structure of the swimming. Herringbone gear drive high-speed axis, in order to automatically compensate for the tooth on both sides of the helix angle error, so that the tooth even by force, using the structure allow the shaft about a small amount of axial swimming, so both ends of selected cylindrical roller bearings . Rather than engage the low speed gear shaft must be fixed at both ends, so that the two axes are the axial position.
Bearings for general use on the shaft of the shaft shoulder or sleeve positioning, the positioning face with its central axis vertical. In order to ensure reliable positioning of the shaft shoulder fillet radius r1 must be less than the bearing of the fillet radius r. Shaft shoulder height is usually not greater than the inner height of 3/4 too high is not easy bearing disassembly.
Axial fixation of the bearing inner ring should be selected depending on the size of the axial load of shaft end retaining ring, round nuts, shaft elastic ring structure. The outer base hole end hole fixed in the form of of Circlips plate, cover.
2 bearing with
The purpose of bearing and the shaft or bearing with the inside, the outer ring is firmly fixed on the shaft or bearing housing, so that mutually harmful sliding. With the surface of the sliding, it will produce abnormal heat and wear, as a result of the wear powder into the bearing and cause early damage and vibration, and other ills, the bearing can not fully perform its functions. In addition, bearing with the impact of the bearing radial clearance, the radial clearance is not only related to the operation of precision bearings and also affected its life.
Rolling is the standard components, and related parts with bore and outside diameter reference holes and the reference axis, do not have to cope with the label. Decided to support the main problem is the load bearing inner and outer rings of the bear state.
In general, the size, load, vibration, high speed or high operating temperature should be selected tight for some with, and often demolition or swim rings loose with.
3 bearing rigidity and concentricity
Shaft and housing must have sufficient rigidity so as to avoid the large deformation of the rolling element Shouli Bu. Bearing hole wall should be of sufficient thickness, and often set the ribs to increase stiffness. In addition, bearing the cantilever should be as short as possible.
The two bearing hole to ensure concentricity in order to avoid the bearing inner ring axis tilt is too large. To this end, both ends of the bearing size should strive for the same, so that a bore can reduce the concentricity error. When the same shaft with the bearings of different diameter size, cup set structure can be used to install the smaller size of the bearing, the bearing bore once boring.
4 Lubrication
(1). Lubrication of rolling bearings
Lubrication of rolling bearings in order to reduce friction and reduce wear, but also have the effect of vibration absorption, cooling, rust and seals. Reasonable lubrication is important to improve bearing performance and extend the life of the bearing.
The rolling bearing hungry lubricating materials, lubricants, greases and solid lubricants, and specific lubrication method according to the speed factor dn value.
The rolling bearing lubricant of choice mainly depends on the speed, load, temperature and other working conditions. Under normal circumstances, the viscosity of the lubricant should not be less than 13mm2 / s ~ 32mm2 / s (ball bearing oil viscosity is slightly lower roller bearing is slightly higher). Optional calcium grease grease lubricated bearings below the low-speed, operating temperature 65 ° C, higher temperature with sodium base grease and sodium or calcium grease; optional lithium grease in the complex high-speed or load conditions; humid environments can be used aluminum grease or barium grease, and should not use the water decomposition of sodium base grease.
(2). Rolling bearing seal
To take full advantage of bearing performance, to prevent the leakage of the lubricant in the grease or oil, but also to prevent harmful foreign body from external intrusion bearings, it is necessary to maximize the use of fully enclosed. The sealing device is one of the important design aspects of the bearing system. Design requirements should be able to achieve long-term sealing and dust effects; friction and installation errors must be small; disassembly, assembly, convenient and simple maintenance.
Sealed in accordance with its principle can be divided into contact seals and non-contact seal two categories. The non-contact seal is not the speed limit. Contact seal can only use the occasion of the line speed is low, in order to ensure the seal life and reduced shaft wear, shaft contact part of the hardness should be HRC40 above, the surface roughness should be less than Ra1.60μm-Ra0.80μm.



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