Apparatus for controlling the tension of a wire fed to a winding machine

An apparatus for controlling tension of a wire fed to a winding machine from a supply, comprising:

• a drive pulley around which the wire rolls after leaving the supply;
• a motor for driving said drive pulley;
• a speed control element coupled to said motor for adjusting the speed thereof;
• an extensometer which includes a pulley assembly through which the wire passes after leaving said drive pully, for measuring the tension in the wire and generating a first electronic signal corresponding to twice the tension of the wire;
• a tachometer coupled to said drive pulley for measuring the speed of movement of the wire at said drive pulley, and generating a second electronic signal proportional to the speed of movement of the wire;
• first means for comparing said first electronic signal with a first preset value signal, corresponding to a predetermined ideal tension in the wire, to generate a third electronic signal which when added to said second electronic signal generates a fourth electronic signal which acts on said speed control element and the wire speed to adjust the tension of the wire to a value corresponding to the ideal tension;
• an arm with a free end and a pulley mounted on said free end of said arm for receiving the wire after leaving the extensometer;
• a spring for biasing said arm to tension the wire;
• a coding wheel located after said arm and its pulley, the wire passing around said coding wheel before leaving the apparatus, said coding wheel generating a fifth electronic signal with a frequency proportional to the speed of the wire;
• means for converting said fifth electronic signal to a sixth electronic signal representative of a variation in said tension of said wire;
• and
• subtraction means for subtracting said sixth electronic signal from a second preset value signal, corresponding to an ideal variation in said tension of the wire for generating said first preset value signal.