ABB Millmate Rolling Force Measurement and Control System On site Troubleshooting and Maintenance Guide

The aging of internal batteries (used for storing configurations) may result in parameter loss. If replacing the controller, it is necessary to re download the configuration file using VIP or RS-232.

5.2 Communication interruption (Profibus or Ethernet)

Check if the terminal resistance of the Profibus connector matches (end to end ON, middle OFF). The highest baud rate is 12Mbit/s.

Ethernet communication: MC 400 serves as the server and adopts a speed of 10Mbit/s. Ensure that the switch port is set to 10M full duplex or auto negotiation.

View controller status LEDs: RUN, ERR, COM, etc. Refer to the code table in the manual.

5.3 Abnormal Analog Output

Measure the voltage/current of the analog output terminal. If the output is zero or full, check the output scaling settings in the controller.

For current output (0-20mA or 4-20mA), the load resistance should not exceed the specified value (usually ≤ 500 Ω).

If higher insulation withstand voltage is required, the insulation amplifier PXUB 201 (voltage or current output) can be used.

Chapter 6 Preventive Maintenance and Life Management

To maximize the fault free operation time of the Millmate system, it is recommended to implement the following maintenance plan:

Cycle content

Check the LED status of the matching unit and controller every week; Record the zero point value without load and monitor the trend

Clean the iron filings and cooling water around the sensor every month to ensure IP protection level (working temperature -10~+90 ℃, short-term 110 ℃)

Quarterly simulation output linearity test (three-point method: 0%, 50%, 100% rated load), deviation should be<0.5%

Perform full-scale calibration of the sensor annually using a standard power source; Check for corrosion on the cable shielding layer and joints

Consider replacing the electrolytic capacitors in the matching unit every 5 years (if any); If the zero drift trend of the sensor exceeds 0.1% per year, it is recommended to send it to the factory for maintenance

Suggestions for spare parts:

Reserve at least one matching unit of the same model (PFVO 142/143) and one set of sensor cables.

For old rolling mills, record the size and load of each sensor. In case of production stoppage, contact ABB for customization (non-standard sizes still need to be calculated as F=(π/4 × (D3 ² - D2 ²)) × 0.0001 MN).

Chapter 7: Case Study: Severe Fluctuations in Rolling Force Readings of Hot Rolling Mill

Background: The rolling force signal of the upper roll of the roughing mill R1 on the 1780 hot rolling mill in a certain factory fluctuates by ± 10% during the rolling process, making it impossible to perform automatic thickness control.

Troubleshooting process:

Observe that the displayed value of the controller fluctuates at a frequency of about 2-3Hz, which is independent of the main motor speed of the rolling mill (about 600rpm), and eliminate transmission interference.

Enter diagnostic mode and view the raw signals of four sensors (two operating sides, two transmission sides). It was found that the upstream sensor signal on the operating side was significantly jumping.

On site inspection of the matching unit of the sensor revealed that the shielding layer at the cable joint had corroded and broken, and the temperature of the matching unit housing was as high as 75 ℃ (close to the upper limit of 90 ℃).

Replace the matching unit and cable, and reconnect the shield. Zero point restoration of stability under no-load conditions.

Conduct simulation testing to ensure linearity of the signal. Test rolling on the machine, the fluctuation decreased to ± 1%, and returned to normal.

Conclusion: Damage to the shielding layer leads to electromagnetic interference coupling into the measurement signal. Regular inspection of cable connectors and shielding grounding is crucial.