KUKA KR CYBERTECH nano-2 maintenance troubleshooting

KUKA KR CYBERTECH nano-2 maintenance troubleshooting

KUKA KR CYBERTECH nano-2 is a six axis articulated robot series launched by KUKA for compact applications, covering three main models: KR 6 R1840-2, KR 8 R1640-2, and KR 10 R1440-2. They are usually paired with KR C5 micro or KR C5 S controllers, with a protection level of IP65, wrist part up to IP67, repeat positioning accuracy of about ± 0.04 mm, body weight of about 153 kg to 162 kg, and maximum arm span from 1440 mm to 1840 mm. This series is suitable for handling, assembly, processing, gluing, testing and other scenarios, with a compact structure and good dynamic performance, but with small maintenance windows, precise cable and toothed belt layout, and high requirements for maintenance standardization. Below, we will discuss several aspects including stopping distance, common faults, planned maintenance, gear belt replacement, oil change, cable group lubrication, electrical interfaces, and installation and transportation.

First, consider safety and stopping distance

The danger zone of KR CYBERTECH nano-2 is composed 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 under KR C5 micro controller as an example, the stopping distance of A1 for KR 6 R1840-2 is about 20.77 °, A2 is about 19.80 °, A3 is about 14.10 °, corresponding to stopping times of about 0.34 s, 0.23 s, and 0.10 s; The A1 of KR 8 R1640-2 is about 19.05 °, A2 is about 17.00 °, A3 is about 11.90 °, and the time is about 0.21 s, 0.21 s, 0.09 s; The A1 of KR 10 R1440-2 is about 16.12 °, A2 is about 13.14 °, A3 is about 12.41 °, and the time is about 0.19 s, 0.16 s, and 0.09 s. If the KR C5 S controller is used, the STOP 0 data will be larger: A1 of KR 6 R1840-2 is about 31.54 °, A2 is about 29.74 °, A3 is about 27.33 °, and the time is about 0.42 s, 0.34 s, 0.16 s; The A1 of KR 8 R1640-2 is about 23.26 °, A2 is about 25.29 °, A3 is about 23.50 °, and the time is about 0.26 s, 0.35 s, 0.14 s; The A1 of KR 10 R1440-2 is about 24.11 °, A2 is about 22.20 °, A3 is about 26.97 °, and the time is about 0.30 s, 0.25 s, 0.18 s. 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. 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 faults and troubleshooting ideas

The stopping distance increases or the braking is abnormal

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.

A5 toothed belt slipping, noise or positioning error

Performance: A5 movement has abnormal noise, increased reverse clearance, and frequency deviation.

Reason: Aging of the toothed belt, insufficient tension, poor engagement of the pulley, and loose adjustment screws.

Solution: After replacing the A5 toothed belt, measure with a frequency meter. The target frequency is 180 ± 5 Hz. When adjusting, first pre tighten the right pulley, then tighten the 2 M3x6-10.9-A2K TORX round head screws, and the final torque should be executed according to the appendix. Note that the toothed belt must mesh correctly and not tilt; There should be no foreign objects between the toothed belt and the pulley.

Gear oil leakage or abnormal oil level

Performance: There are oil stains near A1, A2, and A3, and the temperature is too high during operation.

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 recommended oil is Optigear Synt. ALR 150. First filling amount: A1 is about 0.52 L, A2 is about 0.43 L, A3 is about 0.26 L. The replacement cycle is 20000 hours or 5 years. 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. The torque of the M18x1.5 magnetic plug is approximately 20 Nm. Please note that the oil chamber may be under pressure, and release the pressure before opening the drain plug.

Cable group A1 is worn or has abnormal noise

Performance: The hose inside the base is worn, dust accumulates, and there is friction noise during movement.

Reason: Insufficient lubrication, aging of hoses, long-term high-frequency exercise.

Solution: Remove the base cover, inspect the hose, clean it, and apply Optitemp RB2 grease to the outer surface of the hose, the contact surface with the base, and the inner side of the cover, weighing approximately 0.3 kg. If the hose is damaged, the cable assembly must be replaced. After reassembly, wipe off excess grease and move A1 to evenly distribute the grease.

Zero point loss or Mastering abnormality

Performance: teaching point offset, program unable to reproduce, abnormal axis angle display.

Reason: Replacement of motor, manual release of brake, loss of encoder data, collision.

Solution: Prioritize using EMD or a dial gauge for standard Mastering. The Mastering positions for this series are A1-19 °, A2-90 °, A3 90 °, A4 90 °, A5 0 °, A6 0 °. After replacing the motor, toothed belt, and connecting shaft, the Mastering must be redone.

Connector, grounding, and cable layout faults

Performance: The controller reports motor/data line faults, intermittent shutdowns, and abnormal shielding.

Solution: Check the motor cables, data cables, and grounding conductors. KR C5 micro uses XD20.1/XD20.2-XD30, XF21-XF31; The KR C5 S uses XD20.1... XD20.6-XD30, XD10.1/XD10.2-XD30, XF21-XF31. The cross-sectional area of the grounding conductor is 4 mm ² (micro) or 16 mm ² (S), and the torque of the M8 nut is about 15.0 Nm. The bending radius of the cable should not be less than 5xD when laid in a fixed manner, with a maximum length of 25 m (micro) or 50 m (S), and can be extended up to once. The cable shall not bear tensile force and shall be laid separately from the power line.

The brake is damaged after using the release device

Performance: After manually moving the shaft using the release device, there may be abnormal brake noise or a decrease in braking force.

Reason: The release device forcibly overcomes the brake, which may damage the brake.

Handling: The release device is only for emergency rescue use. After use, the relevant motor must be replaced and all axes must be remade. Subsequently, a braking test was conducted, and abnormal observations were observed during the T1 trial run.

Loose or vibrating base bolts

Performance: Robot shaking during operation, abnormal noise from the feet, and poor repeated positioning.

Reason: Insufficient torque of base bolts, cracking of concrete foundation, and failure of chemical anchor bolts.

Solution: Install the base S260 and use 4 M12x40-10.9 hex bolts with a torque of 104 Nm according to Appendix M12 10.9. Tighten after 100 hours and check annually thereafter. The basic concrete grade shall be at least C20/25.

Planned maintenance: Block faults before they occur

The core nodes of the maintenance table for KR CYBERTECH nano-2 are as follows:

100 hours: Check the torque of the anchor nuts and compression bolts of the foundation.

5000 hours or 1 year: Check for visible hose damage; Lubricate cable group A1; replace A5 toothed belt.

20000 hours or 5 years: Replace A1, A2, A3 gear oil.

Before maintenance, the maintenance point must be accessible and any obstructing tools and accessories must be removed. If the oil temperature exceeds 60 ° C for a long time, the maintenance interval should be shortened and KUKA should be consulted. All accessories must use approved products, otherwise it may lead to early wear and tear. For high-frequency, high load, and high beat applications, the maintenance cycle should be appropriately shortened.

Practical replacement of A5 toothed belt

The replacement of A5 toothed belt is a high-frequency operation in nano-2 maintenance. The steps are as follows:

Place the arm in a horizontal position, the wrist axis in zero position, and A6 without tools.

Remove 9 M4x14-10.9 hex screws and lock washers, and take off the belt side cover.

Remove the M4x16-8.8-A2K adjustment screw, and then remove two M3x6-10.9-A2K TORX round head screws.

Loosen the adjustment screw until the toothed belt can be removed from the pulley.

Install a new toothed belt, ensuring that the toothed belt is correctly engaged with the pulley and cannot tilt.

Move the right pulley to the right, pre tighten the toothed belt, and tighten two new M3x6-10.9-A2K TORX round head screws until the pulley cannot move on its own.

Start the robot and move A5 back and forth within ± 20 ° 2 to 3 times, then move A5 to the 0 ° position and fix it.

Measure the frequency of the toothed belt using a frequency meter. Place the sensor 2 to 3 mm away from the vibrating toothed belt and read the value. The target frequency is 180 ± 5 Hz.

If the frequency does not meet the standard, slightly loosen or tighten the adjustment screw and repeat the measurement until the target value is reached.

After reaching the target value, tighten 2 M3x6-10.9-A2K TORX round head screws step by step.

Check the foam gasket in the cover and replace it if it is damaged. Replace the cover and secure it with 9 new M4x14-10.9 hex screws and locking washers.

Mastering A5 and observing anomalies during T1 trial operation.

Details of oil change and cable group lubrication

When changing the oil, A1 uses an oil pump with a M18x1.5 magnetic plug torque of about 20 Nm; A2 uses an M18x1.5 plug torque of about 20 Nm; A3 uses an M18x1.5 plug torque of about 20 Nm. Before draining the oil, release the pressure first, measure the discharge amount after draining, and the filling amount should be based on the actual discharge amount. When lubricating cable group A1, first remove 5 M6x8-10.9-A2K round head screws, remove the cover and brush strip; Use a brush to apply Optitemp RB2 to the outside of the hose, the contact surface with the base, and the inside of the cover; After reassembly, wipe off excess grease and move A1 to evenly distribute the grease. Lubricating grease is about 0.3 kg, do not exceed it to avoid adsorbing dust.

Electrical interface and installation transportation

The connection cables of KR C5 micro include motor cable XD30, data cable XF31, and grounding conductor. Motor connector 1: XD20.1-XD30, connecting A1-A3 with brake included; Motor connector 2: XD20.2-XD30, connect A4-A6 with brake included. Data cable XF21-XF31. Grounding conductor 4 mm ², M8 ring terminal. The KR C5 S uses 6 motor connectors XD20.1... XD20.6-XD30, 2 brake connectors XD10.1/XD10.2-XD30, data cables XF21-XF31, and a grounding conductor of 16 mm ². The connector must be locked, and there is a "click" sound when the motor connector is locked, and the red locking ring is not visible. During installation, the transportation positions are A1 0 °, A2-120 °, A3 155 °, A4 0 °, A5 80 °, A6 0 °. Use slings or forklifts, and unauthorized lifting is prohibited. Install base S260, 4 M12x40-10.9 bolts, and tighten again after 100 hours. The machine frame installation uses 4 M12x40-10.9 bolts. After installation, enter the installation location, default ground. If used for walls or ceilings, the tilt angle must be entered correctly, otherwise unexpected movement or overload may occur.

Fault Handling Checklist

Emergency stop, power off, padlock, and power check first.

Check the alarm: motor, brake RDC、 Data cables and safety circuits.

Mechanical inspection: oil level, oil leakage, toothed belt, cable assembly, hose, base bolt.

Check parameters: load, center of gravity, inertia, installation angle, program magnification.

After replacement: Mastering, T1 testing, stop distance retest.

Record: Fault time, frequency, axle number, temperature, load, maintenance content.

The reliability of KUKA KR CYBERTECH nano-2 is based on standardized maintenance. By controlling the stopping distance, A5 toothed belt, gear oil, cable lubrication, zero point calibration, and base bolts, most on-site faults can be detected in advance. For engineers, the true idea of "replacing discontinued modules" is not to wait until they break before replacing them, but to use verifiable parameters and standard steps to turn every maintenance into a traceable quality record.