Linear Positioners Catalog_en-US_revA - Kollmorgen

L I N E A R P O S I T I O N E R SLinear Sizing Calculations: Duty CycleDuty Cycle is the ratio of motor-on time to total cycle time andis used to determine the acceptable level of running time sothat the thermal limits of the motor or positioner componentsare not exceeded. Inefficiencies cause a temperature rise ina system, and when the temperature reaches a critical point,components fail. Letting the system to rest idle during the cycleallows these system components to cool. Duty Cycle is limitedby lead screw and motor thermal limits. Use the followingequation and example to determine Duty Cycle:DutyCycle=ON TIMEON TIME + OFF TIME× 100Example:MoveCycleV3 secON TimeDuty Cycle = 3 sec × 1003 + 1 sec= 75%1 secOff TimeLead screw LimitationsCylinders with lead screws have sliding friction surfaces andare limited to a maximum 50% duty cycle regardless of motorcapability. The friction in the lead screw causes rapid heating,and continuous operation is likely to end in a ruined nut orscrew. For positioner with ballscrews the motor is the onlyduty-cycle limitation when used within the listed speed vs.thrust curves in the catalog.Motor TypeElectric motors incur heat losses via a number of paths,namely, friction, ohmic (I 2 R) losses in copper windings,hysteresis and eddy current induction in magnetic corematerials, and proximity and/or skin effect in windings. Asa result duty cycle can be limited by the motor windingtemperature limitations.ServomotorsLinear Positioners using AKM series motors must have theirpeak (Fpeak) and continuous (F RMS ) thrust requirementsdetermined to establish their safe operation within anapplication. F RMS can be determined using the RMS Thrustequation in the Thrust Calculation section. Plotting F RMS onthe positioner Speed vs. Thrust curve indicates the allowableDuty Cycle. For ballscrew positioners, F RMS must fall within thecontinuous duty region, while for lead screws it must fall in the50% duty region. Fpeak must fall within remaining operatingenvelope. The speed vs. thrust curve below is an example ofproper servo electric cylinder sizing.SPEEDEC3-AKM23-xxx-10-10BTORQUE - N-m, lb-in0.0 0.8 1.5 2.3 3.1 3.8 4.6mm/s in/s 0.0 6.8 13.5 20.3 27.1 33.8 40.6635 253810508 203048381 152286VMAX254 101524127 5FRMS762FPEAK0.0 000 70 140 210 280 350 4200 311 623 934 1246 1557 1868MOTORRPMEC3-AKM23-10-10B90K O L L M O R G E N