Structure of the bearing end
    Order to ensure the bearing shafting normal transmission of the axial force does not occur traverse positioned on the shaft parts axially fixed structure on the basis of a fixed, and must be reasonably designed shafting the fulcrum. There are three types of the form of the typical structure.
    (1). Both ends of a one-way fixed
    The minor axis in the normal working temperature (span L <400mm), the fulcrum is often used a fixed manner ends unidirectional, each bearing were exposed to a direction of axial force. Figure 17-15. A small amount of thermal expansion allows the shaft work, bearing installation should be left 0.25mm-0.4mm axial gap (the gap is small, do not have to draw on the structure of Figure), the gap amount commonly gasket or adjustment screw adjustment.
    (2). One end of the two-way fixed, one end of the swimming
    Large amount of shrinkage when the shaft longer or higher operating temperatures, the thermal expansion of the shaft, should be two-way fixed with one end, the fulcrum of swimming at one end structure. The bearing or groups of fixed Duanyou single to withstand two-way axial force, the swimming end to ensure the shaft telescopic swim freely. To avoid loose, swimming in the bearing inner ring with the shaft for axial fixation (circlip often used). Axial cylindrical roller bearings for swimming fulcrum bearing outer ring and base fixed, roll sub ferrule swimming to guarantee the freedom of the shaft telescopic.
    (3) both ends of the swimming
    Requirements around the axis bi-directional swimming, swimming at both ends shafting structure can be used. Herringbone gear drive high-speed drive shaft, in order to automatically compensate for the error of the helix angle of gear teeth on both sides, so that the tooth force uniform structure allows a small amount of axial shafting about swimming, so both ends of the selection of cylindrical roller bearings . Speed gear meshed therewith shafting must be fixed at both ends, so that the two axes are axially positioned.
    Bearing on the shaft is generally positioned with a shaft shoulder or sleeve, the positioning end face of the axis to maintain a good perpendicularity. To ensure the reliable positioning of the shaft shoulder fillet radius r1 must be less than the fillet radius r of the bearing. The height of the shoulder of the shaft is usually not greater than the inner ring of 3/4 of the height of the bearing too high is not easy disassembly.
    The axial bearing inner ring should be based on a fixed axial load size selection shaft end retaining ring, round nut, shaft circlip structure. The outer ring of the end face of the base hole, the circlip holes, pressure plate, cover and other forms fixed.
Bearing with
    The bearing and shaft or bearing, with the purpose of the inner and outer ring firmly fixed to the shaft or bearing housing, so that it does not occur to one another harmful sliding. Mating surfaces produce sliding will generate abnormal heat and wear, as well as the shortcomings of the early damage caused by wear and tear resulting powder into the bearing and vibration, resulting in the bearing can not give full play to its functions. In bearing with can affect the radial clearance of the bearing radial clearance is not only related to the running accuracy of the bearing, affect its life at the same time.
    The bearings are standard components and related parts fit within the hole and the outer diameter of reference holes and a reference axis, and do not have to meet the label. The main problem with the decision is the bearing inner and outer rings of the state to bear the load.
    In general, large size, large loads, vibration, high speed or working temperature higher case should be selected tight some with frequent disassembly or swimming rings adopt a looser fit.
Rigidity and concentricity of the bearing
    The shaft and the bearing housing there must be sufficient stiffness to avoid excessive deformation of the body Shouli Bu. Accordingly, the bearing hole wall should have a sufficient thickness, and often providing the reinforcing ribs to increase stiffness. In addition, the bearing cantilever should be as short as possible.
    Two bearing holes must to ensure concentricity avoid bearing inside and outside the ring axis tilt too large. To this end, both ends of the bearing size should strive for the same, so that once bore concentricity error can be reduced. Same shaft with bearings of different diameter size can be set cup structure to install the smaller size of the bearing, the bearing bore boring.
Lubrication and seal
    (1). Bearing lubrication
    Bearing lubrication primarily to reduce friction and reduce wear, and also have a vibration absorbing, cooling, rust and sealing effect. Reasonable lubrication is important to extend the service life of the bearings to improve bearing performance.
    Lubricating materials bearing hungry lubricants, greases and solid lubricants, the specific lubrication according dn value of the speed factor.
    The bearing lubricant of choice depends primarily on the working conditions of speed, load, temperature, etc.. Under normal circumstances, the use of lubricating oil viscosity should be not less than 13mm2 / s ~ 32mm2 / s (ball bearing oil viscosity slightly lower roller bearing is slightly higher). The optional calcium grease grease lubricated bearings below the low speed, operating temperature 65 ° C to use sodium Grease or calcium sodium grease higher temperatures; optional lithium grease in the complex high-speed or load conditions; humid environments can be selected The aluminum grease or barium Grease, and should not use the water decomposition of sodium grease.
    (2). Bearing seal
    In order to give full play to the performance of the bearing, it is necessary to prevent the leakage of the lubricant grease or oil, but also to prevent harmful foreign matter intrudes from the outside bearing, it is necessary to completely sealed as much as possible. 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 dustproof; friction and installation errors must be small; convenient disassembly, assembly and maintenance simple.
    Sealed in accordance with its principles can be divided into two categories of contact seals and non-contact seal. The non-contact seal is not the speed limit. Contact seals can only use a lower line speed occasions, in order to ensure the life of the seal and reduce wear on the shaft, the shaft contact portion of the hardness should be above HRC40, the surface roughness should be less than Ra1.60μm-Ra0.80μm.


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