CSF CSG PDF - Harmonic Drive LLC

Selection ProcedureSize SelectionGenerally, the operating conditions consist of fluctuating torquesand output speeds. Also, an unexpected impact output torquemust be considered.The proper size can be determined by converting fluctuating load torqueinto average load torque and equivalent load torque. This procedureinvolves selecting the size based on load torque for componentsets.This procedure does not consider the life of the output bearing forhoused units. Determining the life of the output bearing for variousaxial, radial, and moment loads is outlined on page 34.Figure 4Flow Chart for selecting a sizePlease use the flowchart shown below for selecting a size.Operating conditions must not exceed the performanceratings as described on page 13.Calculation of the average output torqueTav = 3 n 1•t 1•|T1| 3 +n2•t 2•|T2| 3 + ... n n•t n•|Tn| 3n 1•t 1+n2•t 2+ ... n n t nMake a preliminary model delection with thefollowing conditions.+Torque_T 1T nT 2T 4T 3t 1 t 2 t 3 t 4 t nn 2n 1n 3n nTimeAverage Output SpeedNav = n 1t 1 + n2t 2 ... + nnt nt 1+t2 ... + tnDetermine Gear Ration i max < = Rn o maxn i max may be limited by the motor.Calculation of the average input speedn i av = n o av •RCalculation of maximum input speedn i max = n o max •Rrpmn 1 n 2 n n are an average value. TimeParametersLoad TorqueTn (Nm)Timetn (sec)Output Speednn (rpm)Normal Operating PatternAcceleration T1,t1, n 1Regular Operation T2,t2, n 2Deceleration T3,t3, n 3Dwell T4,t4, n 4Maximum RPMMax output speedn o maximumMax input speedn i maximumImpact Torquen 4Ts,ts, n sConsider a different Size or change operating requirementsNGNGNGNGNGn i av < = Limit for average speedn i max < = Limit for maximum speedOKConfirm if T 1 and T 3 are less than therepeated peak torque specification.OKConfirm if Ts (impact torque) is less thanthe momentary peak torque specification.OKCalculate the allowable number of rotationsduring impact torque.Ns = 104 ••••••Ns < = 1.0X10 42• n s•R •t s60OKCalculate wave generator life.L h= L n• ()3•( Tr nr Tav n i av)Make sure that the calculated life is suitablefor the application.RatingsRated TorqueRated SpeedTrnr =2000 rpmOKThe model number is determined.Harmonic Drive LLC 800-921-333215