IMPROVED HOT WIRE CONTROL APPARATUS AND METHOD

Control system and apparatus for controlling current input to an electrical resistance element such as a seal wire (2). The system and apparatus of the present invention is a closed loop feedback modification to conventional systems, and takes advantage of the inherent expansion of the seal wire (2) as it is heated. The feedback mechanism monitors the length of the sealing wire, and adjusts the current applied to the wire, responsive to that monitored length. One end of an electric impulse element such as a seal wire (2) is fixed to the underside of a top jaw (20) with a wire tension block. The opposite moving or floating end of seal wire (2) is coupled to a seal wire pivot member (1) at wire terminal (10). A pivot member (1) is pivotally mounted on the top jaw (20) at pivot point (9) so that it moves in response to expansion and contration of the seal wire (2), depending upon the seal wire temperature. A detector actuator (3) in mounted to the seal wire pivot plate or block (1), and extends beyond the pivot member (1) towards detector (5).