US 2018/0007743 A1 · Temperature Sensing Induction Heating Tool

Abstract

An induction heating tool that holds voltage or current supplied to the induction tank circuit constant and tracks changes in the other of voltage or current during each induction heating cycle. The disclosed induction heating tool exploits the fact that the resistance an attachment plate increases along with the temperature of the attachment plate. During an induction heating cycle, the attachment plate is magnetically coupled to a work coil and the resistance of the attachment plate is reflected to the circuit. Changes in the resistance of the attachment plate alter the pattern of energy delivery from the work coil to the attachment plate in a predictable way. Calculations accurately predict the temperature of the attachment plate over a wide variety of ambient conditions, including the presence of moisture at the membrane/attachment plate interface. The disclosed induction heating tool produces consistent results without calibration for ambient conditions.

Claims18

Dependent claims

A method of operating an induction heating apparatus, said method comprising:

providing an induction coil;
connecting a capacitance to said induction coil to form a tank circuit having a resonant frequency;
connecting an output of a power supply to said tank circuit to energize said tank circuit;
providing an electrically conductive work piece;
placing said induction coil adjacent said work piece;
activating said power supply to energize said tank circuit, which resonates at said resonant frequency, said resonating tank circuit generating an oscillating magnetic field which emanates from said induction coil to establish eddy currents in said work piece, thereby heating said work piece;
measuring at least one variable at the output of said power supply;
and
calculating the electrical resistance of the workpiece using measured changes in said at least one variable;
correlating changes in the electrical resistance of the work piece to a temperature of said work piece;
and
deactivating said power supply in response to a calculated change in electrical resistance of the work piece that correlates to a pre-determined target temperature of said work piece.

9 more elements

Dependencies are inferred from the claim text.

Temperature Sensing Induction Heating Tool

Life of this patent

Temperature Sensing Induction Heating Tool

Life of this patent

Abstract

Claims18