The replacement of A3 toothed belt is relatively direct: loosen the 4 M5x20-12.9 screws on the motor flange to remove the A3 motor and toothed belt assembly as a whole, and ensure that the toothed belt is correctly engaged with the pulley during installation. The A4 toothed belt requires additional disassembly of 2 M5 × 20-12.9 screws on the spline triangle block, 4 M6x25-12.9 screws on the bearing support plate, and the guide shaft fixing screw, and the old belt needs to be removed from the gap between the bearing support plate and the support frame.
Tension verification is the core link that determines the quality of replacement. Replace 4 new M5x20-12.9 screws with conical spring washers but do not tighten them yet. Gently tighten the M5 × 40 tension screw, use a frequency meter (TSM alpha 2, order number 0071-053-386) to move the belt and place the sensor 2-3 mm away from the vibration belt to read. Repeat the measurement three times and take the average. The reference frequency is:
A3(860-5GT-12 HSN):47 Hz … 50 Hz
A4(1080-5GT-10 HSN):34.8 Hz … 37 Hz
If the mean does not match, fine tune the tension screw and retest; The fluctuation of tension is a normal phenomenon, and a deviation within ± 30% of the reference value is acceptable. Otherwise, it needs to be readjusted. After confirmation, gradually tighten the 4 M5x20-12.9 screws in diagonal order to 9 Nm, and then tighten the M5 locking nut on the tension screw. When reinstalling the top cover, the torque of the 7 M4x12 screws at the A2 interface is 0.8 Nm, and the torque of the 12 M4x60 screws on both sides of the arm is 1.6 Nm. After completion, the program must be tested in T1 manual deceleration mode and the corresponding axis must be recalibrated.
Battery unit and gear oil replacement
Battery replacement is carried out at interface A1: remove the 4 M3x10-8.8 screws to remove the interface battery unit, connect the spare plug to the new battery, unplug the old battery plug, cut the cable tie to remove the old battery, install the new battery and fix it with 2 new cable ties (be careful not to tie the battery cable). After the replacement is completed, the program must be tested in T1 mode and all four axes of A1-A4 must be re zeroed.
When changing the A1 axis oil, unscrew one M10x1 magnetic screw plug from the bottom frame and connect it to the oil discharge hose. Then slowly unscrew the two M18x1.5 magnetic screw plugs on the connecting rod arm to release pressure and oil; For the A2 axis, the top cover needs to be removed first, and the oil should be drained from the M10x1 screw plug of the connecting rod arm. Refueling uses a KUKA oil pump (0000-180-812) to inject oil in reverse from the bottom. Special reminder: The oil discharge amount is affected by the discharge time and oil temperature, and the oil replenishment amount should be based on the actual measured oil discharge amount; If the oil discharge amount is less than 70% of the specified amount, it must be flushed once with the measured oil amount before injection. If it is less than 50% (such as in inclined installation), it needs to be flushed twice. During the flushing period, the shaft should be run at a jog speed throughout the entire process. Before draining the oil, attention should also be paid to the possibility of pressure in the oil chamber. Release the pressure first before operation, and take precautions against high-temperature oil burns. The locking torque of M18x1.5 screw plug is 20 Nm, and the M10x1 screw plug is 7.5 Nm.
Zero point calibration
After replacing the motor, reducer, cable or battery, the zero point may drift and must be recalibrated. A1/A2 can use the calibration kit (0000-396-617) to align with the calibration slot, and then select Set Current to set the zero point on the KUKA. ControlStudio calibration page; A3/A4 use a dedicated calibration kit (0000-453-614) to seamlessly fit the L-shaped bracket notch with the calibration pin before setting. When there is no calibration tool, calibration can be done by visually aligning the engraved lines, but there may be human judgment errors. The alternative process for A3 zero point is: upper limit position → A4 returns to zero → A3 moves down 4 mm and then sets zero.
