Apparatus and Method for Winding Coil

A method of winding filamentary material on a mandrel rotatable about a spindle axis of rotation and a traverse reciprocating at a distance with respect to said spindle axis to wind said filamentary material in a figure-eight coil configuration with a radial payout hole extending radially from the inner to the outer wind of said coil, comprising:

• controlling the rotation of said mandrel about said spindle axis of rotation to wind filamentary material about said mandrel;
• measuring the diameter of the coil as the filamentary material is being wound about said mandrel, said measuring including:
• measuring a length of filamentary material wound about said mandrel over a time period;
• and
• measuring an angular displacement of said mandrel over the time period;
• and
• determining the diameter of the coil based on a ratio of the measured length of filamentary material wound about said mandrel to the measured angular displacement of said mandrel during the winding of the length of filamentary material about said mandrel;
• and
• controlling, based on the measurement of said diameter, the reciprocating movement of said traverse with respect to the rotation of said mandrel to wind said filamentary material on said mandrel to form said radial payout hole having a constant diameter.

An apparatus for winding filamentary material, comprising:

• a mandrel rotatable about a spindle axis of rotation and a traverse reciprocating at a distance with respect to said spindle axis to wind said filamentary material in a figure-eight coil configuration with a payout hole extending radially from the inner to the outer wind of said coil;
• a measurement device for measuring the diameter of said coil as it is being wound around said mandrel, said measurement device including a diameter determination unit for determining the diameter of the coil based on a ratio of the length of filamentary material wound about said mandrel over a time period to the angular displacement of said mandrel over the time period;
• and
• a controller for controlling the reciprocating movement of said traverse with respect to the rotation of said mandrel based on the measured diameter of said coil to wind said filamentary material on said mandrel in said coil of a figure-eight configuration to form said radial payout hole having a constant diameter.