Tension Control: Maintaining constant tension with FMS products
Winding/unwinding, slitting, coating, printing and many other production processes require constant material tension.
With current drive solutions, sensor technology, bus systems and amplifiers tension control has become state of the art in converting lines, metal, paper and wire manufacturing and processing. Nowadays, tension measuring load cells are part of the standard equipment in running web production lines.
Closed loop tension control principle
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Force sensors measure the effective material tension. |
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The tension controller amplifies the measured signal from the force sensor and calculates an output value from the difference between the reference and feedback values. |
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The drive, brake, or clutch converts the output value from the tension controller into a corresponding torque or speed. |
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Constant tension in the process material can be maintained. |
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Advantages |
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Defined, adjustable material tension |
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Reproducible values in physical units (Newtons, Pounds, etc.) |
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Known manufacturing conditions for finished products (quality recording capability) |
Force Sensors (load cells):
Operational reliability and accuracy of measurement determine the productivity and quality of the processing. The type of processing, the material and factors such as temperature, humidity, and changing winding diameters would lead to continuous variations of the tension in the processed material – without closed loop tension control. FMS Force Sensors determine the tension and send a signal proportional to the tension to the FMS electronic units. The defining characteristics of the individually tested FMS Force Sensors are their capacity to withstand extreme overload conditions while maintaining the highest accuracy in the industry. This is accomplished through built-in mechanical stops to protect against overload and the utilization of foil-type strain gauges installed in a full Wheatstone Bridge configuration in each sensor to ensure the highest measuring accuracy. The sensors have to be determined for each application and FMS provides a wide range of sensors. The calculation can be done very easily with the
Calculator.
Electronic Units:
FMS Tension Measuring Amplifiers and Closed Loop Tension Controllers process the signals from the Force Sensors and have each been specifically developed for use in tension control applications. The measuring amplifiers provide a 0..10V signal or can transmit the feedback values via a Bus System (
ProfiBus, CAN or various Ethernet protocols), while the tension controllers generate a feedback value as well as an output value for a drive, brake, or clutch.
FMS web tension measurement
The web tension in the material (FB) causes a resulting force in the direction of the bisecting line (FM) on a wrapped roller. The measurement of this force is a direct measure of the web tension. The feedback value can be sent to an FMS closed loop tension controller, which regulates a drive, brake, or clutch, ensuring constant material tension throughout the process.