Apparatus and method for controlling tension in a moving material

A method for controlling tension of material being wound on a material winder of the type including a material supply package and a material take-up package, electric motor means for driving the take-up package and a tension responsive dancer arm positioned intermediate said material supply package and said material take-up package for angular movement about an axis proportional to tension variation in the moving material, including the steps of:

• (a) providing polar magnetic means mounted for axial rotation about the axis of movement of said dancer arm in fixed relation to the movement of the dancer arm about said axis;
• (b) providing a semiconductor Hall effect device positioned in perpendicular spaced-apart relation to said polar magnetic means, said Hall effect device having a differential output for sensing the change in the angular position of the polar magnetic means responsive to tension variation in the moving material:
• (c) outputting an electrical signal proportional to the angular position of the polar magnetic means relative to the Hall effect device;
• (d) receiving and processing said electrical signal;
• and
• (e) outputting a voltage and current as required to vary the speed of the motor means to maintain constant tension.

A tension control apparatus for a material winder of the type including a material supply package and a material take-up package, motive means for rotating the take-up package and a tension responsive dancer arm positioned intermediate said material supply package and said material take-up package for angular movement about an axis proportional to tension variation in the moving material, said tension control apparatus comprising:

• (a) position transmitting means mounted for movement responsive to and in relation to the movement of said dancer arm about said axis;
• (b) position sensing means positioned in sensing relation to said position transmitting means for sensing the change in the position of said position transmitting means responsive to tension variation in the moving material and outputting an electrical signal proportional to the position of the dancer arm;
• and
• (c) signal processing feedback circuit means for receiving and processing said electrical signal and outputting a voltage and current as required to vary the operating condition of said motive means to maintain constant tension on said moving material;
• said signal processing feedback circuit means including rate detecting means for measuring the rate at which the dancer arm is moving towards a predetermined set point and calculating the time of arrival of said dancer arm at said predetermined set point.