friction clutches - Arten Freios e Embreagens Industriais

Table of Contents“Air Champ” ®APPLICATION ENGINEERING DATA◗ INERTIA (WK2)The value of WK 2 is important for applications involvingtime, cyclic duty or when starting or stopping heavy loads.Use one or all of the three methods as shown here toestimate the inertia.1. The inertia of solid steel shafting is given in the followingtable. The values shown are for one inch of shaft length.Dia. WK 2(In.) (Lb. Ft. 2 )0.750 0.000061.000 0.00021.250 0.00051.500 0.00101.750 0.00202.000 0.00302.250 0.00502.500 0.00802.750 0.01103.000 0.01603.500 0.02903.750 0.03804.000 0.04904.250 0.06304.500 0.07905.000 0.12005.500 0.17706.000 0.25006.250 0.29606.500 0.34506.750 0.40207 000 0.46407.250 0.5350Dia. WK 2(In.) (Lb. Ft. 2 )7.500 0.61107.750 0.69908.000 0.79108.250 0.89508.500 1.00008.750 1.13009.000 1.27009.250 1.41009.500 1.55009.750 1.750010.000 1.930010.250 2.130010.500 2.350010.750 2.580011.000 2.830011.250 3.090011.500 3.380011.750 3.680012.000 4.000012.250 4.350012.500 4.720012.750 5.110013.000 5.5800Dia. WK 2(In.) (Lb. Ft. 2 )13.250 5.960013.500 6.420013.750 6.910014.000 7.420014.250 7.970014.500 8.540014.750 9.150015.000 9.750016.000 12.610017.000 16.070018.000 20.210019.000 25.080020.000 30.790021.000 37.430022.000 45.090023.000 53.870024.000 63.860025.000 75.190026.000 87.960027.000 102.300028.000 118.310029.000 136.140030.000 155.9200To determine WK 2 of a given shaft or disc, multiply the WK 2 given in the chart bythe length of shaft, or thickness of disc, in inches.NOTE: For hollow shafts, subtract WK 2 of the I.D. from WK 2 of the O.D. andmultiply by length.2. For solid cylinders ofa given weight, WK 2 isestimated from the formula:3. For solid or hollow cylinders, the inertia is calculated by the following equations:Solid CylinderHollow CylinderWK 2 = .000681 p LD 4WK 2 4= .000681 p L (D 2 _ 4 D1 )DLWK 2 = W ( R2 )2WK 2 = lb ft 2Where: D, D 1 , D 2 , L = InchesP = lb/in 3Where: P (Aluminum) = .0924P (Cast Iron) = .260P (Steel) = .282Calculate the inertia of complex, concentric, rotating parts by breaking the part intosimple cylinders, calculating their inertia and summing the values of each.= + +Where: WK 2 = inertia in lb. ft. 2R = cylinder radius in ft.W = weight in lbs.In applications where the speed of the load is different from the speed at the clutchor brake, the value of WK 2 is referred to as reflected inertia.DL◗ TORQUEEnglishCalculate the required torque. Estimate the torque requirements basedon the rated horsepower of the prime mover.T =63000(HP)KRPMT = torque in in. lbs.HP = horsepowerRPM = Speed at clutch or brakeIf the driven load has heavy rotating parts that must be started orstopped in a specific time, evaluate the torque from the formula:T = .039 (WK2 )∆RPMtT = average torque in in. lbs.WK 2 = total inertia load in lb. ft. 2RPM = initial RPM – final RPMt = time in seconds for ∆RPMThe time (t) in seconds required to accelerate or deceleratea rotating mechanism is estimated as follows:t = .039 (WK2 ) RPMTt = required starting or stopping timeWK 2 = total inertia load in lb. ft. 2PRPM = speed at the clutch or brakeT = rated clutch or brake torqueMetricT =P(9545)KnT = torque in Newton meters (Nm)P = transmitted power in kilowatts (kW)n = speed at clutch or brakeIf the driven load has heavy rotating parts that must be started orstopped in a specific time, evaluate the torque from the formula.T =(J)∆nt(9.55)T = average torque in Newton meters (Nm)J = total inertia load in kgm 2∆n = initial RPM – final RPMt = time in seconds for ∆nThe time (t) in seconds required to accelerate or deceleratea rotating mechanism is estimated as follows:t = (J) n(9.55)t = required starting or stopping time in secondsJ = total inertia load in kgm 2∆n = speed at the clutch or brakeT = rated clutch or brake torqueNOTE — A service factor (K) is required to determine the actual torque that the clutch must deliver. For example, some electric motors will deliver three times their rated horsepower for ashort period of time. The clutch or brake must be capable of handling the maximum possible output.NOTE — Torque increases as the speed decreases. Mount the clutch on the highest speed shaft available.363