The tension leveling unit in a recoiling line is primarily used for leveling, flattening, and surface treatment of metal coils. To ensure stable equipment operation and high product quality, the design of the control method and device must align with both process requirements and equipment characteristics. Below is a comprehensive control solution.

1. Core Control Methods

Closed-Loop Tension Control

During decoiling, leveling, and recoiling, the metal strip must maintain consistent tension. A tension sensor continuously collects real-time data, while a PLC system dynamically adjusts motor speed based on preset values. Tension fluctuation is controlled within ±2%, preventing material stretching, deformation, or surface scratches.

Dynamic Adjustment of Leveling Roll Parameters

A multi-roll segmented leveling structure is used. Operators input material parameters such as yield strength and thickness via the HMI. The system then automatically calculates roll penetration values. Pressure gradient is distributed as 40% in the front section, 30% in the middle, and 30% in the rear, effectively eliminating internal residual stress.

Speed Synchronization and Compensation

The decoiler and recoiler use a master-slave control mode. When coil diameter changes, the system applies the real-time formula:
D = √(4L/πθ)
to automatically compensate for line speed differences. A floating roller section absorbs speed fluctuations and stabilizes tension.

2. Key Technical Modules of the Device

Multifunctional HMI Interface

The touchscreen HMI integrates a materials database storing over 200 steel coil parameters. After selecting the material code, the system automatically loads the corresponding leveling parameters. A manual fine-tuning function allows ±5% adjustment for optimized operation.

Surface Quality Inspection System

At the exit of the leveling section, a line-scan CCD camera paired with an LED cold light source performs real-time surface scanning. The defect detection algorithm identifies scratches and dents over 0.1mm by analyzing gray-scale shifts. All inspection data are uploaded to the MES system for traceability.

3. Abnormal Condition Handling

Strip Break Protection

The tension detection module uses a 3-level warning system:

• 80% of preset tension: warning alert

• 60%: automatic speed reduction

• 40%: emergency stop triggered

A hydraulic shearing device is activated with a response time ≤0.5 seconds to prevent equipment damage due to strip breakage.

Automatic Roll Calibration Program

Each time rolls are replaced, the system executes an automatic zeroing process. Servo motors drive the leveling rolls through three full-stroke reciprocating movements. Laser displacement sensors measure positional deviation and upload correction values to the control system. Calibration accuracy reaches ±0.01 mm.

4. Energy Efficiency Optimization

Adaptive Power Regulation

The system automatically switches modes based on production status:

• In standby, motors enter sleep mode, reducing power consumption to 15% of rated values.

• At low speeds (<30 m/min), frequency conversion energy-saving mode is enabled.
  Overall, power usage is reduced by 22% compared to traditional systems.

Intelligent Cooling System

Oil temperature is managed via PID regulation, maintaining a working range of 40–60°C. Sensors collect data every 10 seconds. If the temperature exceeds 65°C, an auxiliary cooling system activates to prevent hydraulic performance degradation.

Maintenance and Operational Notes

• Operators must calibrate tension sensors daily, clean leveling rolls weekly, and verify control system time synchronization monthly.

• During maintenance, prioritize checking the servo motor encoder connections to ensure stable signal transmission.

• In case of shape defects, inspect the matching depth between the third and fourth leveling rolls.