Siemens SINUMERIK 840D sl Function Manual

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K3: Compensation5.6 Friction compensation (quadrant error compensation)Extended FunctionsFunction Manual, 09/2009, 6FC5397-1BP20-0BA0 419Commissioning stage 2: Friction compensation with adaptationApplicationWhenever friction compensation depends on the acceleration and the required resultscannot be obtained with constant injection amplitude, adaptation must be used.In order to obtain optimum compensation over the whole of the working range of the frictionfeedforward control where high demands are made on accuracy, the accelerationdependency of the compensation value must be calculated. To achieve this, the dependencymust be measured at various points in the working range between acceleration zero and themaximum planned acceleration. The adaptation characteristic derived from themeasurement results is then entered in the above machine data axis-specifically.1. Calculate the adaptation characteristicFor different radii and velocities ...1. ... it is necessary to determine the required injection amplitudes,2. ... it is necessary to check the compensatory effect of the injection amplitudes using thecircularity test,3. ... it is necessary to log the optimum amplitudes.The adaptation characteristic is defined completely by the settings of the parametersspecified in Section "Conventional friction compensation". However, many more measuredvalues must be obtained for checking purposes. It must be ensured that there is a sufficientlylarge number of interpolation points for small radii at high speed. The size of the curves mustbe obtained by plotting.2. Determining acceleration valuesFor circular movements, the axial acceleration values are calculated with radius r and thetraversal velocity v according to the formulaa = v 2/rThe velocity and thus also the axial acceleration value a can be varied easily by means ofthe feedrate override switch.The acceleration values a 1, a 2 and a 3 for the adaptation characteristic must be entered in therelevant machine data in compliance with condition a 1 < a 2 < a 3:MD32550 $MA_FRICT_COMP_ACCEL1(adaptation acceleration value 1)toMD32570 MA_FRICT_COMP_ACCEL3 (adaptation acceleration value 3)If the curve is wrongly parameterized, the alarm 26001 "Parameterization error for frictioncompensation" is output.