What are the tolerances and finishes for plain bearings and shaft mating surfaces?
1) the bearing and the shaft are matched with the base hole system, and the shaft shaft system is used to match the bearings and the housings.Bearing size tolerance and rotary accuracy shall be calculated according to GB307 - 84 corrosion resisting pump.2) the shaft neck and the bearing box bore with the bearing are specified according to GB1031 - 83. The Ra value of the shaft neck roughness is less than 1.6 mu m, and the bore roughness Ra of the bearing case is less than 2.5 mu m.3), bearing rings and roller manufacturing with GCr15 and ZGCr15 steel, the ring and the roller hardness value should be equal to 61~65HRC; GCr15SiMn and ZGCr15SiMn steel, the hardness of this value should be 60~64HRC. The hardness check method and the uniformity of hardness of the same part shall be stipulated by JB1255.4) check the bearings, radial clearance and axial clearance should be in line with GB4604 - 84 rules.5), rolling bearing the outer ring raceway should be no peeling, severe wear, both inside and outside the ring no after crack; ball should wear, the holder no serious deformation, rotation without abnormal noise and vibration should be gradually stopped, stop gap. 6, for the C tolerance class tapered roller bearing, the roller and raceway contact with a precision pump load with Germany for shrimp, color check into good, contact traces should be continuous, contact length should be less than no bus 80 roller.
Tolerances and surface roughness of mating surfaces of plain bearings and shafts:1. milling machines, drilling machines and lathes, gear reducer and worm gear reducer using sliding bearings, sliding bearing holes and shaft outside circleMatching H7/f7; surface roughness: sliding bearing bore Ra0.8, outer circle Ra0.8---Ra0.4.2. motors, centrifugal pumps, fans, steam engines, sliding bearings used in crankshaft and connecting rods of internal combustion engines, sliding bearings, bores, and shaftsMatching H9/f9; surface roughness: sliding bearing bore Ra0.8, outer circle Ra0.8---Ra0.4.3. agricultural machinery use of sliding bearings, sliding bearing holes and shaft outer circle, select H11/d11;Surface roughness: internal bore of sliding bearing Ra1.6, outer circle Ra3.2---Ra1.6.
1, the types of tolerance fit into three categories: gap fit (formerly called: dynamic coordination), transition coordination, interference fit (formerly known as: static coordination).2, clearance fit - the shaft and hole there is a clear gap between the coordination, the shaft can be turned in the hole3, the interference fit - there is no gap between the shaft and hole, the shaft and hole close together, the shaft will not be able to rotate alone4, transition coordination between gap fit and interference fit, there may be a gap, there may be interference, such coordination can be used as a precise positioning of the coordination5, when the need to rotate in the hole, choose clearance fit, require relatively large gap H11/c11 (such as: hand mechanism), requirements can rotate, and the gap is not too large demands on the choice of H9/d9 (such as: the idle band with the wheel and shaft), even if the gap with precision select the H8/f7 (such as sliding bearing with)6, if you want the shaft and hole fixed together to rotate, rotate together, to bear the load together with the load, can choose the fit, with little surplus amount can pass relatively small force, relatively large force will make the axis of rotation and hole assembly can be used wooden percussion hammer assembly. With type H7/n6, with large interference can express great force and general press assembly, or by the temperature difference method for assembly, for example: with the train wheel rim and hub, is to use the temperature difference method for assembly interference fit with type H7/z67, the need for precise positioning, but also need to be able to disassemble, such as rolling bearings, inner ring and shaft coordination, outer ring and hole fit, you can choose H7/js6, or H7/k6Hope that the above can help you
