Mechanical axis, bearings and tolerance - bearing knowledge

Bearing ( A) Bearing function and categories: the function of the bearing is a supporting shaft and the shaft rotational parts to keep its certain rotating accuracy, the load, but also to reduce the relative rotation between parts caused by friction and wear. According to the nature of the bearing work can be divided into sliding bearing and rolling bearing. Rolling bearing is widely used in all kinds of mechanical bearing parts; Most of sliding bearing used in high-speed, overloading, and has bigger impact load or particularly high on the axis of rotation accuracy requirements of mechanical equipment, especially the need to use the occasion of split structure. ( 1) Rolling bearings: (1) single-row radial ball bearing Radial bearing, deep groove ball bearing) Point: mainly bear radial load, large shaft rigidity requirements applicable places: on the gearbox and the spindle type said: cases of type 6305 (2) double row centripetal ball bearings ( Self-aligning ball bearing) Point: mainly bear radial load, double row ball, outer ring raceway is spherical shape, with automatic self-aligning properties, can automatically compensate coaxiality error due to flexure and shell deformation applicable occasions: bearing seat hole can guarantee strict alignment of parts. Model said: the cases of 1207 type, 3303 type ( Imports) (3) spherical roller bearing, The centripetal short cylindrical roller bearing) Point: mainly bear radial load, but also can withstand the axial load in one direction, have high radial load capacity. Applicable occasions: overloading or work under vibration load. Model said cases of type 2000 (4) cylindrical roller bearing point: bearing inner and outer circle can be separated, this type of bearings is separable, inner ring can make free axial movement applicable occasions: the bearing used to bear radial load models, 'said N000 Nj202E ( Import model, inner ring guard) NU206EC（ Inner ring no guard) (5) angular contact ball bearing, Angular contact ball bearing) Points: can the radial load and axial load at the same time, also can withstand pure axial load, limit rotational speed is higher, the bearing capacity of axial load is determined by contact Angle, the bigger the alpha, carry axial load ability, the greater the α= 15°α= 25°α= 40°) Applicable occasions: angular contact ball bearings for can only bear the axial force of single direction, so this kind of bearing should be used in pairs, such as spindle installation method: ( i) Method one: the ends of the bearing outer ring is relatively narrow edge, called is installed ( Commonly known as face to face) , blend the bearing's outer ring assembly, the small clearance, grinding narrow bearing outer ring. ( ii) Method 2: both ends of bearing outer ring side is relatively wide, called reverse installation ( Commonly known as back to back) , bearing rigidity can be improved, and improve the stress of the shaft. Assembly blend bearing inner ring, the small gap, grinding narrow bearing inner ring. ( iii） Method 3: synthetic two sets of assembly, assembly precision of 0. 006-0. 014 mm gap adjustment, preload adjustment to 0. 006 mm, fit clearance is 0. 001-0. 004 mm 6 points: single row tapered roller bearing mainly applies joint under radial and axial load, Radial) , big cone Angle can also bear is given priority to with axial load of diameter, the axial union load, bearing to bearing separation type, can be adjusted in the process of installation and use of bearing radial clearance and axial clearance and preloaded mounting can be made. Applicable occasions: speed is not too high, rigid axial and radial load large axis, such as helical gear shaft type said: 30202 ( Imports) Divides into 7 needle roller bearing inner ring needle roller bearing ( The type 74000) And without inner ring needle roller bearing ( The type 84000) 。 Model said: example INA. ZARN2572- TU- ANA GERMANY02 / B07 - with shaft hole phi 25, cylindrical phi 72. Today a one-way thrust ball bearing ( The type 8000) Bidirectional thrust ball bearing, The type 38000) Commonly known as plane bearing. ( 2) Sliding bearing: usually give priority to with copper collar, Hydrostatic bearing, commonly known as floating bearing)