CSF CSG PDF - Harmonic Drive LLC

Output Bearing LifeHow to Calculate Life of the Output BearingThe life of a cross roller bearing can be calculated by equation (15).equation (15)L 10 =10 6 x( C ) 10/360xNav fw.PcEquation 15L 10 Life Hour ––––––––Nav Average Output Speed rpm equation 13C Basic Dynamic Rated Load N table 30Pc Dynamic Equivalent N equation 16fw Load Coefficient ––––– list 3List 3Load Coefficient, fwSteady operation without impact and vibration 1~1.2Normal operation 1.2~1.5Operation with impact and vibration 1.5~3Dynamic Equivalent Radial LoadHow to Calculate Life for Oscillating MotionThe Life of a cross roller bearing in a oscillating operationcan be calculated by equation 18equation (18)90 x( C ) 10/3Loc =10 6 x60xn1 Ø fw.PcSymbol of equationLoc Rated life for oscillating motion Hour ––––––––n1 Round trip oscillation each minute rpm ––––––––C Basic dynamic rated load N ––––––––Pc Dynamic equivalent radial load N equation 16fw Load Coefficient ––––– list 3Ø Angle of oscillation/2 degrees refer to figurefigure 8equation 16Pc = X . ( 2 (Frav ( Lr + R ) + Faav . La)) + Y . FaavdpSymbol of equationFrav Average radial load N equation 11Faav Average axial load N equation 12dp Pitch diameter m table 30X Radial load coefficient –––––– list 2Y Axial load coefficient ––––––– list 2ØLr, La Moment Arm m figure 6R Offset m figure 6 and table 30How to Calculate Static Safety CoefficientBasic static rated load is an allowable limit for static load,but its limit is determined by usage. In this case, static safety coefficientof the cross roller bearing can be calculated by equation 17.Reference values under general conditions are shown on list 4.Static equivalent radial load can be calculated by equation (17)equation (17)fs =CoPoSymbols for equation (17)Co Basic static rated load N table 30Po Static equivalent radial load N refer to equation (19)Rotating Conditions Load Conditions Lower Limit Value for fsNormally not rotating Slight oscillations 0.5Impact loads 1-1.5Normally rotating Normal loads 1-2Impact loads 2-3list 4Oscillating AngleA small angle of oscillation (less than 5 degrees) may cause fretting corrosion tooccur since lubrication may not circulate properly.equation (19)Po = Frmax + 2Mmax + 0.44. FamaxdpSymbols for Equation (19)Frmax Max. radial load NFamax Max. axial load NMmax Max. moment load Nmdp Pitch diameter m35