A Tension Control based on radius computation
Precise control of winding tension in centre-driven spoolers or coilers is essential to eliminate loose coils, material breakage and telescoping. In many applications, direct contact with the material (for the purpose of sensing the roll diameter) is also not desirable. Positioning of tension transducers or dancers.
Dynaspede CTC is a cost-effective tension controller adequate for most centre-winding or unwinding applications. Since its first introduction in 1978, Dynaspede CTC has undergone continual refinements to occupy a pride of place in applications as varied as Wire drawing, Textiles, Paper, Films and Foil converting industries.
This versatile controller is adaptable in a variety of torque control devices such as Eddy Current or DC drives, Magnetic Particle or pneumatic clutches-brakes.
 Acceptability of a complex system depends on many factors such as the degree of tension, accuracy, nature of the material, buildup (or turndown) ratio, and tension range. Speed match during acceleration, deceleration or line speed changes is also necessary to compensate for the effects of roll inertia. Further, a controlled “taper tension” is needed to avoid telescoping of the material during winding.
Dynaspede offers CTC 307 series specifically for such applications as a reliable, cost-effective and easy means of tension control with many attractive features and add-ons.
Standard Features
- Nothing touches the web: The system is completely automatic over 12:1 build-up ratio. Set the running tension, stalling tension and taper, and the control takes care of the rest.
- Built-in flexibility: The system can be adapted to control most torque devices—brakes or clutches exercising electrical control of torque, such as eddy current or magnetic particle devices, pneumatic or hydraulic clutches—brakes or torque control through DC motors.
- Versatile: The same models can be used for winders and un-winders.
- Compact design: The system is suitable for stand-alone or panel mounting applications.
 Principle of Operation
Dynaspede Tension Controller operates on the principle of electronic computation of the roll diameter, at every instant during the winding process and controls the shaft torque to maintain the desired web tension. The operation of a tension reeler is defined by the following relationship.
Tension (T)= shaft torque (Tq) / radius of roll(R)
or Torque = Radius x Tension
Thus, depending on the change in the diameter of the roll during the winding process, the torque (Tq) must be varied proportionately in order to maintain a constant web tension. For a given linear speed (V), the mandrel rpm (N) must reduce proportionately with the roll diameter (D), governed by the relationship V =P.D.N. Therefore, the radius of the roll, can be calculated by electronically dividing the line speed signal (V) by the roll rpm signal (N).
 These signals are made available to the controller from separate speed sensors (Tachogenerators) that monitor the line speed and roll rpm.
At any given line speed, therefore, we need to provide a constant horsepower control to the mandrel (NxTq is kept constant) in order to maintain the operating tension. Also, for a given roll diameter, the shaft torque to be applied for a desired tension is constant, regardless of the line speed. Thus the applied horsepower must vary in direct proportion to the line speed. During changes in line speed, torque must be added or subtracted depending on whether the line speed is increasing or decreasing, to compensate for the inertia of the roll and other transmission elements.
In most winding applications it is desirable to have the web tension gradually tapering down with increasing build-up to avoid telescoping. Constant torque winding refers to the case of 100% taper and constant tension is achieved under conditions of zero taper. An infinite adjustment between these limits is therefore desirable to cater to all winding applications.
 The schema alongside gives the functional blocks and modes of control incorporated in Dynaspede centre-wind Tension Controller. The Electronic Dividing Block (E.D.B) outputs a signal proportional to the instantaneous roll diameter and controls the torque in proportion to maintain the set tension. |
Tension Control Systems
