Induction heating system having multiple temperature input control

• US 20060289495A1
• Filed: 06/03/2005
• Published: 12/28/2006
• Est. Priority Date: 06/03/2005
• Status: Active Grant

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Thomas, Jeffrey R., Baxter, Randall G., Verhagen, Paul D., Beistle, Edward G.
• Granted Patent: US 7,786,415 B2
• Time in Patent Office: Days
• US Class Current: 219/677
• CPC Class Codes: H05B 6/06 Control, e.g. of temperature, of power
• CPC Class Codes: H05B 6/101 for local heating of metal pieces
• CPC Class Codes: H05B 6/40 Establishing desired heat distribution, e.g. to heat particular parts of workpieces

Abstract

A system and method for inductively heating a work piece. The induction heating system is coupleable to a plurality of temperature feedback devices operable to provide a signal representative of work piece temperature. The induction heating system is operable to control the output of the induction heating system based on the plurality of signals representative of work piece temperature received from the plurality of temperature feedback devices.

Claims

1. An induction heating system, comprising:

an induction heating power source; and

a controller configured to control output of the induction heating power source based on a plurality of signals representative of work piece temperatures at a generally common time of induction heating at a portion of a work piece, wherein the controller is operable to select an outlier signal from the plurality of signals representative of work piece temperatures to control the output of the induction heating power source based on a programmed control scheme.

3. The system as recited in claim 1, wherein the controller is programmed to select a signal representative of the greatest work piece temperature from the plurality of signals representative of work piece temperatures as the outlier signal to control the output of the induction heating power source.

4. The system as recited in claim 1, wherein controller is operable to calculate a rate of work piece temperature change for each of the plurality of signals representative of work piece temperatures, and wherein the controller is programmed to select the signal representative of the greatest rate of work piece temperature increase to control the output of the induction heating power source to prevent the work piece from exceeding a desired rate of work piece temperature increase.

5. The system as recited in claim 1, wherein the controller is operable to calculate a rate of temperature decrease for each of the plurality of signals representative of work piece temperatures, and wherein the controller is programmed to select the signal representative of the greatest rate of temperature decrease to control the output of the induction heating power source.

6. The system as recited in claim 1, wherein the controller is electrically coupleable to an induction heating device operable to receive power from the induction heating power source and to produce a varying magnetic field to heat the portion of the work piece.

7. The system as recited in claim 6, wherein the induction heating power source is operable to select the lowest temperature represented by the plurality of signals representative of work piece temperatures, and wherein the induction heating power source is operable to regulate power to the induction heating device based on the lowest temperature to maintain the work piece above a minimum temperature.

8. The system as recited in claim 7, wherein the controller is programmed to select the signal representative of the greatest work piece temperature and to control power to the induction heating device to prevent the greatest temperature represented by the plurality of signals representative of work piece temperatures from increasing above maximum desired temperature.

10. The system as recited in claim 6, comprising a fluid cooling system operable to supply a flow of cooling fluid to the induction heating device.

11. The system as recited in claim 1, wherein the controller is programmed to select the signal representative of the lowest work piece temperature to control the output of the induction heating source during a cool down from an elevated temperature to a lower temperature.

12. The system as recited in claim 1, wherein the controller comprises a processor operable to receive programming instructions and a the plurality of signals representative of work piece temperature from each of a respective one of a plurality of temperature feedback devices, wherein the processor is configured to select one of the plurality of temperature feedback devices to control the induction heating power source based on the signal from the selected temperature feedback device and the programming instructions.

13. The system as recited in claim 12, comprising a user interface, wherein the user interface enables a user to input programming instructions to direct the induction heating system to heat portion of the work piece to produce a desired temperature in the work piece.

14. The system as recited in claim 12, comprising an interface adapted to enable the plurality of temperature feedback devices to be communicatively coupled to the processor, wherein the interface comprises a plurality of analog-to-digital converters configured to convert each of the signals representative of work piece temperatures to a digital signal representative of work piece temperature.

15. The system as recited in claim 12, comprising a selector operable to sequentially couple each of the digital signals representative of work piece temperatures to the processor.

17. The system as recited in claim 12, wherein the controller is operable to direct the induction heating power source to heat the portion of the work piece at a desired temperature for a desired period of time, and the processor is pre-programmed to measure the desired period of time from when all of the work piece temperatures are within a pre-designated range.

26. The system as recited in claim 1, comprising a plurality of in-situ work piece sensors configured to output the plurality of signals.

27. The system as recited in claim 1, comprising an induction heating coil configured to couple to the induction heating power source, and a plurality of sensors configured to obtain the plurality of signals in proximity to the induction heating coil.

28. The system as recited in claim 1, wherein the induction heating power source comprises the controller.

29. The system as recited in claim 1, wherein the controller comprises an in-situ temperature feedback comparator coupled to a power level controller.

39. The induction heating system of claim 1, wherein the controller is configured to control output of the induction heating power source based on at least three signals representative of work piece temperatures.

40. The induction heating power system of claim 1, comprising an induction heating coil disposed about a welded portion of a pipe.

41. The induction heating power system of claim 1, comprising a metal work piece and a plurality of temperature sensors welded to the work piece, wherein the plurality of temperature sensors are coupled to the controller and are configured to output the plurality of signals.

42. The induction heating power source of claim 1, wherein the induction heating power source is operable to relieve stress in a welded portion of the work piece.

2. (canceled)

9. (canceled)

16. (canceled)

18. A method of controlling operation of an induction heating system, comprising:

inductively heating a portion of a workpiece with electromagnetic energy output from an induction heating system;

receiving a plurality of signals each indicative of a temperature at a respective one of a plurality of locations on the portion of the work piece, wherein the plurality of signals are received while the portion of the workpiece is inductively heated;

selecting an outlier signal from among the plurality of signals;

controlling the output of the induction heating system based on the outlier signal.

19. The method as recited in claim 18, wherein selecting an outlier signal comprises selecting the signal indicative of a highest temperature, a fastest increasing temperature, a slowest increasing temperature, a lowest temperature, a fastest decreasing temperature, or a slowest decreasing temperature, or a combination thereof.

20. The method as recited in claim 18, wherein selecting an outlier signal comprises selecting a signal representative of the greatest work piece temperature, and wherein controlling the output comprises reducing the output of the induction heating system in response to the outlier signal rising above a predetermined maximum.

21. The method as recited in claim 18, wherein selecting an outlier signal comprises establishing a rate of temperature change represented by each of the plurality of signals, and selecting the signal representative of the greatest rate of temperature change, and wherein controlling the output comprises adjusting the output of the induction heating system in response to the outlier signal indicating a rate of change that is greater than a pre-selected maximum rate of change.

23. The method as recited in claim 18, wherein selecting an outlier signal comprises selecting a signal representative of the lowest work piece temperature, and wherein controlling output comprises increasing output of the induction heating system in response to the outlier signal indicating a temperature below a pre-selected minimum temperature.

24. The method as recited in claim 18, wherein recieving a plurality of signals comprises sequentially receiving the plurality of signals from an analogue-to-digital converter.

30. The method as recited in claim 18, comprising receiving the plurality of signals from a plurality of sensors disposed in general proximity to an induction heating coil.

31. The method as recited in claim 18, wherein controlling output of the induction heating power source controlling output based on a plurality of signals representative of work piece temperatures at a generally common time of induction heating at a portion of a work piece.

22. (canceled)

25. A tangible medium having a computer program to control an induction heating power source, comprising:

code configured to compare a plurality of signals indicative of temperatures at different locations on a heated portion of a generally static workpiece, select a signal indicative of an extreme condition based on the comparison, and control output of the induction heating power source based on the signal.

32. The tangible medium as recited in claim 25, comprising code configured to receive the plurality of signals from a plurality of sensors disposed in general proximity to an induction heating coil.

33. The tangible medium as recited in claim 25, comprising code configured to control output of the induction heating power source based on a plurality of comparative signals representative of work piece temperatures at a generally common time of induction heating at a portion of a work piece.

34. A system, comprising:

an induction heating power source;

a multi-sensor interface configured to simultaneously couple to the induction heating power source and a plurality of work-piece temperature sensors, wherein the multi-sensor interface is configured to receive a plurality of temperature signals representative of a plurality of work-piece temperatures from the plurality work-piece temperature sensors; and

a temperature responsive controller configured to couple to the multi-sensor interface and configured to exercise in-place feedback control over inductive heating of a work-piece by selecting one signal of the plurality of temperature signals that is an outlier and controlling in response to the one signal.

35. A system, comprising:

an induction heating power source;

an in-place controller coupled to the power source; and

at least three in-place work-piece temperature sensors coupled to the in-situ controller, wherein the controller is configured to compare signals from the in-place temperature sensors, select an outlier signal from among the signals, and control output of the heating power source based on the outlier signal.

36. The system as recited in claim 35, wherein the in-place controller comprises an in-place temperature comparator.

37. The system as recited in claim 35, wherein the induction heating power source comprises the in-place controller.

38. The system as recited in claim 35, comprising an induction heating coil and the plurality of in-place work-piece temperature sensors disposed in general proximity with the induction heating coil.