Atlas Copco PowerMACS 4000, User Manual

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Set Up and Maintenance
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4.17.3.5 Current (torque)
The step types TC - Run until Torque with Current Control, DT - Run until Dyna-TorkTM, DT2 - Run until
Dyna-TorkTM, method 2, and DT3 - Run until Dyna-TorkTM, method 3 are uses the servo current
measurement for step control. The programmed set torque value is converted to a current set value with
the T/C factor. The current set value is used in the servo and the servo shuts off itself.
The T/C factor
The spindle parameter T/C factor (Torque/Current) (see Spindle Set Up, Calibration page) is the scale
factor for all current control. The unit of the T/C factor is [<torque_unit>/A] and a theoretical value based
on the motor data is used as default setting. The value of the T/C Factor can not be changed since it is
written at spindle production and depends on the motor. Instead a
T/C Correction Factor can be
specified to calibrate the torque/current conversions.
One way to calibrate the T/C Correction Factor
is to select “Current” as control parameter under “Torque
usage” in the Spindle Set Up form (see General).
Use the “Single Run” function located of the Test Bolts form.
Run 10 cycles and register the torque values from an inline torque transducer. Calculate a mean torque
value and adjust the
T/C-factor if necessary. Increased TC-factor decreases the true torque.