KUKA KR CYBERTECH-3 HW maintenance troubleshooting

KUKA KR CYBERTECH-3 HW maintenance troubleshooting

KUKA KR CYBERTECH-3 HW is the hollow wrist version of the KR CYBERTECH-3 platform, also known as Hollow Wrist. Its core feature is to guide wire feeding tubes, protective gas tubes, cables, etc. from the inside of the wrist to the welding gun or tool end, reducing external pipeline interference and improving the posture flexibility and accessibility of applications such as arc welding, laser welding, and cutting. This series is usually paired with KR C5 S6/S7 controllers, with a protection level of IP54, and the wrist part can reach IP67. The repeat positioning accuracy is about ± 0.03 mm, the body weight is about 237 kg, the maximum arm span is 1840 mm, and the workspace is about 24.4 m ³. Hollow wrist brings convenience, but also brings new maintenance difficulties: internal pipeline wear, difficult cleaning, small maintenance window, and high zero calibration requirements. Below, we will discuss several aspects including stopping distance, common faults, planned maintenance, oil change, cable group lubrication, internal pipelines, zero point calibration, installation and transportation, and electrical interfaces.

First, consider safety and stopping distance

The danger zone of KR CYBERTECH-3 HW consists of both workspace and stopping distance. The stopping distance is not a fixed value, it is affected by program magnification, load, extension distance, and brake wear. Taking STOP 0 as an example, the stopping distance of A1 on the same platform KR 25 R1840-3 is about 27.86 °, A2 is about 23.98 °, and A3 is about 35.09 °; The corresponding stop times are approximately 0.25 s, 0.26 s, and 0.26 s. The stopping distance for A1 of KR 35 R1840-3 is about 34.75 °, A2 is about 17.30 °, and A3 is about 34.18 °; The stopping time of A1 is about 0.34 seconds. The HW version may have slight differences in actual stopping distance due to increased inertia and friction in the wrist internal pipeline, and must be based on on-site measurements and controller documentation. STOP 1 varies with program magnification and mass, and the corresponding curve needs to be checked.

If it is found on site that the robot's sliding after braking has significantly increased, there is abnormal braking noise, and there is repeated positioning drift, the first reaction should not be to change the program, but to check the brake wear and stopping distance. It is recommended to retest the stopping distance at least once a year, especially under frequent triggering of STOP 0, high cycle, and high load conditions. STOP 0 has a significant impact on the mechanical system and should be avoided as much as possible; In situations where STOP 1 or STOP 2 can be used, the lower impact stopping method should be preferred.

Strict habits must be formed for safe operation: switch T1 before entering the danger zone, press emergency stop, cut off the main switch and lock it; If it is necessary to debug in the powered on state, it can only run at low speed T1 and ensure emergency stop at any time. After the robot loses power, the power components may still be charged for a short period of time. Wait for at least 5 minutes and verify the power. The motor and brake will generate electromagnetic fields, and personnel wearing active implants such as pacemakers should maintain a distance of at least 300 mm. The surface temperature of the motor is high, and protective gloves must be worn when replacing or inspecting it. When it comes to electrical operations, strictly follow the five safety rules: power off, prevent accidental restart, confirm no power, ground short circuit, and block adjacent live parts; After the work is completed, restore in reverse order.

Common fault one: abnormal stopping distance and brake wear

Performance: Stop position deviation, increased collision risk, and abnormal braking sound in automatic mode. Reason: Brake wear, incorrect input of load data, high program magnification, external axis stacking motion, and dragging of internal pipelines in the hollow wrist. Processing: Verify the load data in the controller, including mass, center of gravity Lx/Ly/Lz, moment of inertia Ix/Iy/Iz, and A/B/C directions; Verify with KUKA Load; Check the brake system; Retest the stopping distance. If there is a change in load or supplementary load, it must be re inputted, not based solely on experience.

For the HW version, if the wire feeding tube, trachea, and cables inside the hollow wrist are not properly arranged, they will generate additional resistance during movement, resulting in a longer stopping distance. Therefore, when investigating abnormal stopping distance, in addition to the brake and load, it is also necessary to check whether the internal pipelines of the wrist are worn, stuck, or loose. If the internal pipeline is severely worn, it must be replaced, otherwise it may simultaneously affect the stability of wire feeding and braking performance.

Common Fault 2: Gear Oil Leakage and Oil Change

Performance: There are oil stains near A1, A2, A3, A4, and A5, the temperature is high during operation, and metal shavings are attached to the magnetic plug. Reason: seal aging, screw plug not tightened according to torque, incorrect oil quantity, installation angle leading to incomplete oil discharge. Solution: Replace the gear oil according to the shaft.