KUKA KR CYBERTECH-3 maintenance troubleshooting

KUKA KR CYBERTECH-3 maintenance troubleshooting

KUKA KR CYBERTECH-3 is a six axis articulated robot series launched by KUKA for medium to high load applications. The current document covers two models, KR 25 R1840-3 and KR 35 R1840-3. Both have a body weight of approximately 237 kg, a maximum arm span of 1840 mm, a workspace of approximately 24.4 m ³, a repeat positioning accuracy of approximately ± 0.03 mm, a protection level of IP54, and an IP67 wrist section. They are typically paired with KR C5 S6/S7 controllers. KR 25 R1840-3 has a rated load of 25 kg and a maximum load of 38 kg; KR 35 R1840-3 has a rated load of 35 kg and a maximum load of 49 kg. They can be used in scenarios such as handling, assembly, processing, palletizing, and inspection. They have a compact structure and good dynamic performance, but require high installation, cable layout, and planned maintenance. Below, we will discuss several aspects including stopping distance, common faults, planned maintenance, oil change, cable group lubrication, zero point calibration, installation and transportation, and electrical interfaces.

First, consider safety and stopping distance

The danger zone of KR CYBERTECH-3 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 KR 25 R1840-3 at A1 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 stop time of A1 is about 0.34 seconds. STOP 1 varies with the 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.

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. 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 KR 25 R1840-3, the stopping distance and stopping time of A3 are prominent, indicating that the axle has a high braking load during high-speed motion. For KR 35 R1840-3, the stopping distance of A1 and A3 is relatively large, especially at high loads. Therefore, if it is found on site that the A3 has slid longer after braking, priority should be given to checking the A3 motor brake, gearbox, and load data. If the stopping distance of A1 is abnormal, the base fixation, cable dragging, and A1 motor brake should be checked. Abnormal stopping distance is often not a single cause, but the result of the combined effects of mechanical wear, load parameters, and program magnification.

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.

The maintenance table in the document shows that when KR 25 R1840-3 is replaced with A5 gear oil at 20000 hours or 5 years, the initial filling amount is about 0.15 L; when A4 gear oil is replaced, the initial filling amount is about 0.20 L. Similarly, when KR 35 R1840-3 is replaced with A5 gear oil at 20000 hours or 5 years, the initial filling amount is about 0.15 L and A4 is about 0.20 L. In addition, when it is replaced with A3 at 20000 hours or 5 years, the recommended oil is Optigear Synth. ALR 150. Oil discharge must be carried out at operating temperature and the discharge volume measured. If the discharge volume is less than 70% of the specified amount, it should be rinsed once; If it is less than 50%, rinse twice. The filling amount shall be based on the actual discharge amount. Be aware that the oil chamber may be under pressure, and release the pressure before opening the drain plug. The torque of the screw plug shall be executed according to the appendix. The M18x1.5 magnetic screw plug is usually about 20 Nm, and the M10x1 is about 7.5 Nm. After changing the oil, check for leaks and observe abnormalities during T1 operation.