P.A.C.E. Inc. - Tension Torque Control

Green = Tension calculated from Drum Motor Current, Speed, Friction & Inertia compensation

Figure 1 - Tension Feedback Comparison

Tension Control through Torque FB 1. General Paper winder tension control is crucial for maintaining consistent roll quality, preventing defects, and ensuring smooth operation during various paper processing stages. It involves managing the force applied to the paper web as it's wound onto a roll, affecting aspects like roll hardness, separation, and runnability. Effective tension control helps to avoid wrinkles, sags, and changes in web dimensions, which can lead to register errors and other problems in printing and other processes. 2. Load Cell Control Nowadays the most common & effective tension control is with loadcells. The signal of the loadcells is amplified and calibrated to the machine physics to basically give a readout in PLI. There are basically 2 different systems for tension control: 1) Rewinder with an active drive system on the unwind 2) Rewinder with a passive brake system on the unwind In case of an active drive system on the unwind the loadcell signal is sent directly to the drive, and the unwind drive regulates speed & force to constantly hold the desired tension. With a passive brake system on the other hand side the loadcell signal is sent to a brake amplifier or to the PLC with the proper program and that’s where the corresponding brake force is regulated to reach the required tension. 3. Load Cell Failure In case the loadcell system fails and does not provide the correct feedback, the only other option is to look at the drive force and regulate the tension by calculating it from the measured torque in the unwind drive. If the winder does not have an unwind drive to measure the torque the problem gets much more sophisticated, but it is still solvable by working with the measured torque of the drums. 4. Additional new Program to run the Winder without Loadcells We developed a new feature for winders with brakes on the unwind to replace the loadcell signal. For the most accurate equivalent of the loadcell signals we measure & calculate: - Drum Drive Speed - Drum Drive Current - Unwind Jumbo Diameter - Unwind Jumbo weight (Density of the paper is required) - Acceleration & Deceleration rate - Friction & mechanical Loss Compensation - Inertia Compensation The result is a curve very similar to the actual loadcell feedback – see the trend below that shows both curves together and how much they are alike. 5. Trend of actual loadcell feedback in comparison to the new feature of a calculated tension As we can see, the result of the new program and the calculations give us a curve which is very similar to the real tension measured by the loadcells. It accounts for any speed change as well as for the acceleration & deceleration variations.

6.

System Implementation

This new system is for winders with no drive on the unwind, but instead a brake system. It can be implemented on any newer and fast PLC system with low processing time, which guarantees better response time. Signals needed from other systems: - Drive Speed - Drive Current - Unwind Diameter - Paper Density All calculations and tests will be done while the winder is running to measure various factors & losses like: - Friction Loss - Inertia - Speed impact

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Process Automation Consulting Enterprises Inc. - P.A.C.E. Inc.

Green = Tension calculated from Drum Motor Current, Speed, Friction & Inertia compensation

Figure 1 - Tension Feedback Comparison

Tension Control through Torque FB 1. General Paper winder tension control is crucial for maintaining consistent roll quality, preventing defects, and ensuring smooth operation during various paper processing stages. It involves managing the force applied to the paper web as it's wound onto a roll, affecting aspects like roll hardness, separation, and runnability. Effective tension control helps to avoid wrinkles, sags, and changes in web dimensions, which can lead to register errors and other problems in printing and other processes. 2. Load Cell Control Nowadays the most common & effective tension control is with loadcells. The signal of the loadcells is amplified and calibrated to the machine physics to basically give a readout in PLI. There are basically 2 different systems for tension control: 1) Rewinder with an active drive system on the unwind 2) Rewinder with a passive brake system on the unwind In case of an active drive system on the unwind the loadcell signal is sent directly to the drive, and the unwind drive regulates speed & force to constantly hold the desired tension. With a passive brake system on the other hand side the loadcell signal is sent to a brake amplifier or to the PLC with the proper program and that’s where the corresponding brake force is regulated to reach the required tension. 3. Load Cell Failure In case the loadcell system fails and does not provide the correct feedback, the only other option is to look at the drive force and regulate the tension by calculating it from the measured torque in the unwind drive. If the winder does not have an unwind drive to measure the torque the problem gets much more sophisticated, but it is still solvable by working with the measured torque of the drums. 4. Additional new Program to run the Winder without Loadcells We developed a new feature for winders with brakes on the unwind to replace the loadcell signal. For the most accurate equivalent of the loadcell signals we measure & calculate: - Drum Drive Speed - Drum Drive Current - Unwind Jumbo Diameter - Unwind Jumbo weight (Density of the paper is required) - Acceleration & Deceleration rate - Friction & mechanical Loss Compensation - Inertia Compensation The result is a curve very similar to the actual loadcell feedback – see the trend below that shows both curves together and how much they are alike. 5. Trend of actual loadcell feedback in comparison to the new feature of a calculated tension As we can see, the result of the new program and the calculations give us a curve which is very similar to the real tension measured by the loadcells. It accounts for any speed change as well as for the acceleration & deceleration variations.

6.

System Implementation

This new system is for winders with no drive on the unwind, but instead a brake system. It can be implemented on any newer and fast PLC system with low processing time, which guarantees better response time. Signals needed from other systems: - Drive Speed - Drive Current - Unwind Diameter - Paper Density All calculations and tests will be done while the winder is running to measure various factors & losses like: - Friction Loss - Inertia - Speed impact

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