9.4.8
Determining the maximum axis jerk value
The "jerk limitation" function of the control reduces the jerk occurring when
the velocity is changed. This in turn reduces the peak load of the mechanics
and the drive components. At the same time, the excitation of the system to
oscillate is reduced. To be able to parameterize the jerk limitation, the maxi‐
mum possible jerk value of an axis must be determined.
This is most easily achieved by determining the value graphically by means
of the oscilloscope. Select a positioning operation of the NC program and
zoom the acceleration out of standstill. Then measure the time T from stand‐
still to the point in time when the velocity changes linearly. Determine the ve‐
locity V that is reached at this time. The maximum axis jerk is calculated us‐
ing the formula "J=V/T²". The following figure explains the procedure:
Fig. 9-23:
Determining the axis jerk
The value set in the CNC should be 10% higher than the calcula‐
ted value. If, e.g., a value of 60 was calculated, 66 should be set.
Now enter the value increased by 10% in relation to the calculated value in
the "Maximum axis jerk" CNC parameter for this axis. Additionally set "Axis
jerk reserve" to half the value of "Maximum axis jerk". Restart the CNC to ac‐
tivate the settings.
DOK-MTXMIC-EASY*******-CO06-EN-P
Bosch Rexroth AG
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IndraMotion MTX micro Easy Setup for Standard Turning and Milling Machines
Commissioning the drives
