>> P.455
KBefore attempting to calculate the life, make sure that the operating conditions are within the permissible range by referring to the pV diagram in Fig.1. When the operating conditions are out of the permis-sible range, please consult IKO. The contact pressure p and the sliding velocity V are obtained from the following equations.p= 100P Cdt……………………………………(3)V=5.82×10-4where,p:Contact pressureN/mm2dkβf ………………………(4) P:Equivalent radial load N (Refer to equation (2). ) Cdt:Dynamic load capacity considering temperature increaseN(Refer to equation (1).) V:Sliding velocitymm/s dk:Sphere diametermm2β:Oscillating angledegrees (Refer to Fig.2.) (Refer to the dimension tables.) when β<5°, β=5 when rotating, β=90f:Number of oscillations per minutemin-1When alternate loads are applied, this range is also permissible.Permissible range100806040201068421N/mm2pContact pressure124610204060100200Sliding velocityVmm/sFig.1 pV diagram of Steel-on-steel spherical bushingsOscillating angleFig.2 Oscillating angleK6Table 10 Temperature factorftTemperature℃Type of bushing-30+80+80+90+ 90+100+100+120+120+150+150+180Steel-on-steelWithout sealsWith sealsMaintena nce-freeWithout sealsWith seals11111-1-1-1-1-0.90.750.55---0.7--- 2 Static load capacityThe static load capacity Cs is the maximum static load that can be applied on the spherical bushing without breaking inner and outer rings or causing any perma-nent deformation severe enough to render the bush-ing unusable.It must be noted that if the magnitude of the applied load becomes comparable to the static load capacity of bushing, the stresses in the shaft or housing may also reach to their limits. This possibility must be taken into consideration in the design.Equivalent radial loadSpherical Bushings can take radial and axial loads at the same time. When the magnitude and direction of loads are constant, the equivalent radial load can be obtained from the following equation.P=Fr +YFa …………………………………(2)where, P:Equivalent radial loadN Fr Radial loadN Fa:Axial loadN Y:Axial load factor (Refer to Table 11.)Table 11 Axial load factorYFa/Fr0.10.20.30.40.5>0.511223345UnusableUnusableType of bushingSteel-on-steelMaintenance-freeLifeThe life of Spherical Bushings is dened as the total number of oscillating motions before the bushings cannot be operated normally because of wear, increase in internal clearance, increase in sliding torque, rise of operating temperature, etc.As the actual life is affected by many factors such as the material of the sliding surface, the magnitude and direction of load, lubrication, sliding velocity, etc., the calculated life can be used as a practical measure of expected service life. 1 Life of Steel-on-steel spherical bushings[1]Conrmation of pV value
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