Cornerstone Automation advised a leading manufacturer of bulk conveyor belting to utilize AC drives and motors to gain greater torque control, resulting in a complete elimination in noise, a reduction in heat, quantum electricity savings, and the elimination of air consumption.
A manufacturer of bulk conveyor belting used pneumatic drag brakes and clutches to maintain tension for wide swaths of fabric in a slow vulcanizing process both for unwind roll and rewind roll operations. Drag brakes and clutches can be noisy, hot, and inefficient. The inefficiency of a pneumatic clutch results from running a motor at full load and inserting the clutch in between the motor and load. The amount of friction is determined by air pressure.
Enter advanced AC drives which when coupled to a vector duty motor with encoder feedback can perform this same clutch function by using its built-in advanced torque control. The AC drive produces only enough speed and torque required by the process to maintain web tension and can be dynamically controlled either by an operator or a closed loop with a sensor. Unlike the drag clutch which runs the motor at full torque and current, and then uses yet more power for compressed air to slow that motor’s torque, AC drives only use the power needed to maintain the product tension.
Again, AC drives with torque control and a vector-duty motor can maintain web roll tension in unwind applications with drag brakes. The drive can operate in multiple quadrants which means there is control of velocity and torque in both positive and negative directions. Additionally, AC drives with regeneration capabilities can create further savings because the motor becomes a generator, and electricity is put back into the plant! With the elimination of the maintenance costs of the drag brake, compressed air, and hardware, increased savings are realized.
This customer experienced a complete elimination in noise, a reduction in heat, quantum electricity savings, and the elimination of air consumption. Other benefits included preset and tracking speed and torque changes with digital communications built into most modern drives. Digital torque and speed offer more accuracy and repeatability over the long run. Overall equipment effectiveness (OEE) data and SCADA information is available for further analysis by the client.
Equipment used:
- Rotary curing press (rotocure press)
- Allen-Bradley PowerFlex AC drives
- Allen-Bradley PLC ControlLogix
- Marathon AC motors
To learn more about whether an AC or DC motor is best for your application, you can reference this article. If you would like more information about how Cornerstone Automation can assist you with your web tension control project, contact us today!