KUKA KR 300 R2700-2 C-F maintenance troubleshooting

KUKA KR 300 R2700-2 C-F maintenance troubleshooting

KUKA KR 300 R2700-2 C-F is a high load six axis articulated arm robot with a rated load of 300 kg, a maximum load of 366 kg, a maximum arm span of 2671 mm, a body weight of approximately 1105 kg, a workspace of approximately 51.8 m ³, a repeat positioning accuracy of approximately ± 0.05 mm, and a protection level of IP65/IP67. It is usually paired with KR C5 M6/M7 or KR C4 controllers. Its installation method is mainly ceiling mounted, and the cast version also comes with positive pressure inside the arm, special paint, dust and coolant resistance design. For on-site engineers, the real tricky problem is often not "replacing one part", but how to determine the root cause of the fault without increasing downtime, and complete the replacement, calibration, and testing according to specifications. Below, we will discuss troubleshooting logic, planned maintenance, oil change, balance cylinder, motor and connecting shaft, and zero point calibration.

First, check the safety and shutdown distance

The danger zone of this model 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 as an example, the stopping distance of A1 is about 32.24 °, A2 is about 14.85 °, and A3 is about 17.46 °; The corresponding stop times are approximately 0.67 s, 0.38 s, and 0.38 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.

Low pressure or abnormal operation of the balance cylinder

Performance: Insufficient A2 axis support force, operational shaking, abnormal noise from the balance cylinder, and pressure gauge reading below requirements.

Reason: Nitrogen leakage, hydraulic oil leakage, aging seal, long-term lack of inspection.

Solution: Manually move A2 to -90 °, wait for 1 minute, emergency stop, connect pressure gauge, wait for 3 minutes, and read the pressure. The minimum pressure at 20 ° C is 244.8 bar. If the value is lower than this or there is a deviation in the application, the balance cylinder must be replaced. The balance cylinder weighs about 40 kg and is under pressure. Before operation, it must be depressurized to zero. Two cranes should be used in conjunction, and attention should be paid to the thrust ring and spacer ring during disassembly and assembly. Microlube GL 261 should be applied.

Gearbox oil leakage or abnormal oil level

Performance: There are oil stains near A1, A2, A3, A4, A5/A6, and metal shavings are attached to the magnetic plug. 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. Initial filling amount: A1 is about 8.30 L, A2 is about 2.10 L, A3 is about 1.40 L, A4 is about 2.10 L, A5/A6 is about 1.40 L (ZH210/ZH210F) or 1.90 L (ZH300/ZH300F). 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 M18x1.5 magnetic plug is about 20 Nm, A4 is 40 Nm, and A1 union nut is 45 Nm.

A5/A6 abnormal after oil change

Performance: A5/A6 abnormal noise, positioning error, insufficient fuel level.

Reason: Incorrect oil discharge and filling angle, incorrect oil distribution.

Processing: Move A4 to+90 ° for oil discharge, 0 ° for lower part, and -90 ° for filling; Add about 1/3 to A5 first, and the remaining to A6. After adding, check if the three magnetic plugs are leaking.

Motor overheating, brake failure, or wear of involute teeth

Performance: High motor temperature, difficult release of brake, A1-A6 motion shaking.

Reason: Load exceeding limit, high ambient temperature, insufficient lubrication of teeth, aging of O-ring, improper installation of motor.

Solution: Check the involute teeth, clean and apply Microlube GL 261, thin and continuous. The O-ring must be replaced if it is damaged. When installing the motor, tighten the screws diagonally and step by step to the specified torque. Before replacing A2/A3, the connecting rod arm or robot arm must be fixed with a crane to prevent the arm from falling down after disassembling the motor. Pay attention to the connecting shaft and compression spring when replacing A4/A5; If there is a back up ring on the old motor shaft, it must be discarded and cannot be reused. A6 replacement requires the dismantling of A4, A5, and the inline hoist, which weighs approximately 100 kg and must be reliably lifted.

Wear of connecting shaft

Performance: Large movement gap, abnormal noise, and positioning drift in A4/A5.

Reason: Tooth wear, insufficient lubrication, and damage to the tooth surface during installation.

Solution: The connecting shafts must be replaced in pairs. Clean the teeth and apply Microlube GL 261 before installation. Ensure that the teeth are correctly engaged and not tilted when installing the inline writer.

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. Zero position: A1-25 °, A2-100 °, A3 100 °, A4 0 °, A5 0 °, A6 0 °. After replacing A4/A5/A6 or inline writer, adapt to MAMES value and re master. The accuracy of emergency Mastering is relatively low, and standard methods should be used to recalibrate as soon as possible afterwards.

Casting plate positive pressure loss

Performance: Pollution inside the arm, entry of dust, accelerated wear of bearings and teeth.

Reason: The gas source contains water and oil, insufficient pressure, and pipeline leakage.

Solution: Check the overpressure inside the arm at 0.03 MPa (0.3 bar) ± 10%. The compressed air should be free of oil and water, in accordance with ISO 8573-1:2010 (7:4:4), with a gas consumption of approximately 0.1 m ³/h and a joint of 6 mm. The wrist thermal load is 10 s/min at 180 ° C. Pressure loss can cause dust and coolant to enter, and it must be repaired in a timely manner.

Connector, cable, and grounding 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 C4 uses X20-X30, X21-X31; KR C5 uses XD20.1... XD20.6-XD30, XD10.1/XD10.2-XD30, XF21-XF31. The cross-sectional area of the grounding conductor is 16 mm ², and the torque of the M8 nut is about 23 Nm. When the cable bending radius is fixed and laid, the motor cable should not be less than 150 mm, and the data cable should not be less than 60 mm. The maximum length is 50 m, and it can be extended up to once. The cable shall not bear tensile force and shall be laid separately from the power line. Do not attach other cables to the cable group, and do not fix them with zip ties or Velcro to avoid restricting movement and causing breakage.

Planned maintenance: Block faults before they occur

The core nodes for maintaining a table are as follows:

After 100 hours: Check the torque of the fastening screws and nuts.

2500 hours or 1 year: lubricate the balance cylinder bearings using LGEP 2, with each lubrication nozzle approximately 10 cm ³, and add oil at the middle position, positive and negative end positions respectively; Check the pressure of the balance cylinder.

10000 hours or 5 years: Replace A1, A2, A3, A4, A5/A6 gear oil.

10 years: Replace the balance cylinder.

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.

Key points of oil change practice

A1 (ceiling installation): Drain oil through a quick connector and add oil from below with a union nut torque of 45 Nm. A2: M18x1.5 plug, 20 Nm. A3: M16x1.5 plug, 20 Nm, A3 level. A4: M18x1.5 plug, 40 Nm, A3 level. A5/A6: Drain oil at A4+90 °, drain the lower part at 0 °, add oil at -90 °, add 1/3 to A5 first, the remaining to A6, M18x1.5 screw plug 20 Nm. Check for leaks after each oil change, and observe abnormalities during T1 operation.

Balance cylinder inspection and replacement

Inspection: Manually adjust A2 to -90 °, wait for 1 minute, emergency stop, connect pressure gauge, wait for 3 minutes, and read the value. Minimum 244.8 bar at 20 ° C. If it is lower than this value, it must be replaced. When replacing, first release the pressure and drain the oil until the pressure is zero. Remove the 4 M8x20-10.9 screws and retaining plate, use a pin puller to remove the pin, and pay attention to the thrust ring and spacer ring. Apply Microlube GL 261 before installing the new balance cylinder, and recheck the pressure after installation. The balance cylinder contains nitrogen and hydraulic oil, and is a pressure equipment that must be operated by qualified personnel.

Key points for replacing the motor and connecting shaft

A1:4 M12x25-8.8-A2K, coated with Microlube GL 261, check the O-ring and F-plate seal. A2/A3:4 M12x25-8.8-A2K, first fix the connecting rod/arm with a crane, and then remove the motor. A4/A5: 4 M8x25-8.8-A2K, remove the connecting shaft, check the compression spring, discard the old back up ring. A6:4 M8x30-8.8-A2K, A4, A5, and inline writer need to be disassembled first. In line writer: 20 M10x200-10.9 pieces, approximately 100 kg, must be reliably lifted. Mastering A4/A5/A6, T1 test after replacement.

Foundation, flange and load

Basic load: Fv normal 17000 N, max 24900 N; Fh normal 8600 N，max 20600 N； Mk normal 19800 Nm，max 43200 Nm； Mr normal 8000 Nm，max 17300 Nm。 The maximum load is used for foundation design and must be followed. Flange load: Running F (a) 4800 N, F (r) 4500 N, M (k) 3200 Nm, M (g) 1700 Nm; Emergency stop F (a) 8700 N, F (r) 12600 N, M (k) 6700 Nm, M (g) 5700 Nm. The tool must be able to withstand these loads.

Transportation, storage, and disposal

Transportation location: A1 0 °, A2-137 °, A3 160 °, A4 0 °, A5-105 °, A6 0 °. Use forklifts or cranes, unauthorized lifting is prohibited. The storage environment should be dry, dust-free, avoid temperature differences and sunlight, with a temperature range of -40 ° C to 60 ° C. During disposal, the balance cylinder must be depressurized first, the motor should not be disassembled, electronic components should be treated as electrical waste, and plastics should be classified according to labeling.

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, balance cylinder pressure, connecting shaft, involute gear, O-ring.

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 300 R2700-2 C-F is based on standardized maintenance. By controlling the six stages of stopping distance, balancing cylinder pressure, oil and oil quantity, motor installation, connecting shaft tooth surface, and zero point calibration, 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.