Method and system for control of on-site induction heating

• US 7,015,439 B1
• Filed: 11/26/2001
• Issued: 03/21/2006
• Est. Priority Date: 11/26/2001
• Status: Active Grant

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Thomas, Jeffrey R., Baxter, Randall G., Ulrich, Mark A., Verhagen, Paul D.
• Primary Examiner(s): Leung, Philip H.
• Application Number:
  US09/995,165
• Time in Patent Office: 1,576 Days
• Field of Search: 219/667, 219/665, 219/663, 219/635, 266/80, 266/87, 266/96, 266/99, 266/129
• US Class Current: 219/667
• CPC Class Codes: H05B 6/06 Control, e.g. of temperature, of power

Abstract

A workpiece heating system having an induction heating power source and a controller. The controller is operable to control the operation of the power source according to programming instructions received from a user. The controller enables a user to establish a sequence of inductive heating operations to be performed automatically by the induction heating system from among a selection of inductive heating operations. A temperature feedback device may be included to provide the controller with the workpiece temperature. A data recorder may be provided to receive and record the workpiece temperature.

Claims

1. An induction heating system, comprising:

a power source operable to produce an alternating current to inductively heat a workpiece;

a controller operable to control operation of the power source, wherein the controller is operable to receive programming instructions to selectively increase and decrease workpiece temperature at a desired rate of change and to automatically control operation of the power source to provide inductive heat to the workpiece to selectively increase and decrease the workpiece temperature at the desired rate of change; and

a temperature feedback device operable to provide the controller with an electrical signal representative of the workpiece temperature.

2. The system as recited in claim 1, comprising a data recorder operable to record workpiece temperature data.

3. The system as recited in claim 1, wherein the power source is operable to provide sufficient power to enable the system to perform stress relief of a workpiece.

4. The system as recited in claim 3, wherein the controller is programmable to direct the system to inductively heat a workpiece to perform the stress relief of the workpiece automatically.

5. The system as recited in claim 1, wherein the controller is operable to control operation of the power source to lower the workpiece temperature at a desired rate of temperature decrease automatically.

6. The system as recited in claim 1, wherein the controller enables a user to establish the desired rate of temperature change by providing a specific desired rate of temperature change.

7. The system as recited in claim 1, wherein the controller enables a user to establish the desired rate of temperature change by providing a desired time period for the workpiece temperature to change and a specific temperature change.

8. The system as recited in claim 1, wherein the controller is operable to control the power source to maintain workpiece temperature at a desired temperature for a desired period of time.

9. The system as recited in claim 8, wherein the controller is operable to change workpiece temperature to a desired workpiece temperature.

10. The system as recited in claim 1, wherein the controller utilizes Proportional-Integral-Derivative (PID) control.

11. The system as recited in claim 1, comprising a data recorder operable to record workpiece temperature data received from at least one temperature feedback device.

12. The system as recited in claim 1, wherein the controller utilizes Proportional-Integral (PI) control.

13. An induction heating system, comprising:

an induction heating power source;

a temperature feedback device operable to provide the system with workpiece temperature data; and

a controller operable to control operation of the induction heating power source to increase workpiece temperature to an elevated temperature and to reduce workpiece temperature from the elevated temperature to a lower temperature at a desired rate of temperature decrease automatically in response to programming instructions and the workpiece temperature data.

14. The system as recited in claim 13, comprising a data recorder, wherein the data recorder records the workpiece temperature data digitally.

15. The system as recited in claim 14, comprising a disc drive, wherein the data recorder is operable to transfer data to the disc drive for storage on a digital recording media.

16. The system as recited in claim 13, comprising a plurality of temperature feedback devices, wherein the data recorder is operable to record workpiece temperature data from each of the plurality of temperature feedback devices.

17. The system as recited in claim 16, wherein the plurality of temperature feedback devices are thermocouples.

18. The system as recited in claim 13, comprising a PCMIA module operable to transfer data from the recorder.

19. The system as recited in claim 13, comprising a networking module operable to couple the recorder to a network.

20. A system controller for an induction heating system, comprising:

a control unit operable to control operation of an inductive heating power source automatically in response to programming instructions; and

a user interface to enable a user to provide the programming instructions to the control unit, wherein the user interface enables a user to establish a sequence of inductive heating operations to be performed automatically by the induction heating system from a selection of inductive heating operations to control the rate of temperature change in a workpiece.

21. The system controller as recited in claim 20, wherein the desired rate of temperature change is a decrease in workpiece temperature.

22. The system controller as recited in claim 20, wherein one of the inductive heating operations in the selection of inductive heating operations directs the system to maintain workpiece temperature at a desired temperature for a desired period of time.

23. The system controller as recited in claim 20, wherein one of the inductive heating operations in the selection of inductive heating operations directs the system to change workpiece temperature from a current workpiece temperature to a new workpiece temperature.

24. The system controller as recited in claim 20, wherein the system controller is operable to store the sequence of inductive heating operations to be performed automatically by the induction heating system for use in a subsequent inductive heating operation.

25. A system for heating a workpiece, comprising:

a power source electrically coupleable to an induction heating device; and

a system controller, comprising;

a control unit operable to control operation of an inductive heating power source automatically in response to programming instructions; and

a user interface to enable a user to provide the programming instructions to the control unit, wherein the user interface enables a user to establish a sequence of inductive heating operations from a selection of inductive heating operations that may be performed automatically by the induction heating system to control the rate of temperature change in a workpiece.

26. The system as recited in claim 25, wherein the power source and system controller are portable.

28. The system as recited in claim 26, wherein the controller and a data recorder are housed in a common enclosure.

27. A system for heating a workpiece, comprising:

an induction heating device;

a power source operable to transmit power to the induction heating device;

a controller operable to control operation of the power source automatically to heat the workpiece according to a desired workpiece temperature profile, wherein the controller is operable to heat the workpiece at a first rate of temperature increase during a first portion of the workpiece temperature profile and to heat the workpiece at a second rate of temperature increase during a second portion of the workpiece temperature profile, the second rate of temperature increase being different than the first rate of temperature increase.