Method and apparatus for controlling the temperature of continuously fed wires

An apparatus for controlling the thermal state of a welding wire which is continuously fed and heated between two electric contact tips having a dielectric gap of a predetermined length therebetween, the heating being effected by electric current being passed between the two contact tips and through the wire, said apparatus comprising:

• welding wire feed means for delivery of the welding wire to the electric contact tips;
• welding wire feed rate monitor means for determining the welding wire feed rate and generating a first output signal reflective thereof;
• power supply means in communication with the electric contact tips for delivering a controlled current to the electric contact tips;
• current sensing means in communication with said power supply means for generating a second output signal reflective of the current provided by said power supply;
• and
• computer means responsive to said first output signal reflective of said wire feed rate and said second signal reflective of said current and generating a control signal to which said power supply is responsive in order to effect the application of current to the electric contact tips, said computer means being programmed with a predetermed series of temperature isotherms based on established welding wire characteristics such that for a desired average temperature for a welding wire of known composition, the appropriate level of preheating power is applied to the electric contact tips.