Apparatus for induction hardening

Patent metadata

Field	Value
Publication number	US-9920392-B2
Application number	US-201514630706-A
Country	US
Kind code	B2
Filing date	Feb 25, 2015
Priority date	Oct 11, 2010
Publication date	Mar 20, 2018
Grant date	Mar 20, 2018

Abstract

An apparatus for magnetic induction hardening of a workpiece includes a magnetic tool having a body portion formed of a generally non-magnetic material. The body portion has a surface configured to be positioned in close proximity to the workpiece being hardened. The apparatus further includes a magnetic arrangement coupled to the body portion at or adjacent the surface of the body portion and configured to provide regions of alternating polarity. A workpiece holder is configured to support the workpiece in close proximity to the surface of the magnetic tool. A drive arrangement for rotating the magnetic tool relative to the workpiece holder about an axis of rotation is provided to induce heating of the workpiece to achieve a temperature in the austenitic range of the workpiece resulting in hardening of the workpiece through a microstructural transformation.

First claim

What is claimed is:

1. An apparatus for magnetic induction hardening of a workpiece, the apparatus comprising:
a magnetic tool having
a body portion formed of a generally non-magnetic material, the body portion having a surface configured to be positioned in close proximity to the workpiece being hardened, the surface of the body being a radially inwardly-facing circumferential surface configured for induction hardening an outer surface of the workpiece; and
a magnetic arrangement coupled to the body portion at or adjacent the surface of the body portion and configured to provide regions of alternating polarity;

a workpiece holder configured to support the workpiece in close proximity to the surface of the magnetic tool such that the workpiece is received in a bore formed in the magnetic tool and is surrounded by the magnetic arrangement; and
a drive arrangement for rotating the magnetic tool relative to the workpiece holder about an axis of rotation to induce heating of the workpiece to achieve a temperature in the austenitic range of the workpiece for hardening of the workpiece through a microstructural transformation;
wherein the magnetic tool includes a mounting portion coupled to the body portion and spaced from the magnetic arrangement, wherein the mounting portion includes a mounting shaft sized and configured to be received in a spindle, and wherein the drive arrangement includes a drive unit operable to rotate the spindle.

2. The apparatus of claim 1 , further comprising a quenching system operable to quench the heated workpiece while it is supported by the workpiece holder.

3. The apparatus of claim 2 , wherein the magnetic tool and the workpiece holder are movable relative to one another in a direction parallel to the axis of rotation between a first position for heating the workpiece, and a second position for quenching the workpiece.

4. The apparatus of claim 2 , wherein the quenching system includes a quench collar surrounding the workpiece for showering the workpiece with a quenching medium.

5. The apparatus of claim 2 , wherein the quenching system includes a conduit coupled to the workpiece holder to be positioned at least partially within the workpiece.

6. The apparatus of claim 1 , wherein the magnetic arrangement includes a plurality of permanent magnets coupled to the body portion at or adjacent the surface and configured to provide the regions of alternating polarity.

7. The apparatus of claim 6 , wherein the body portion includes a plurality of pockets formed therein and spaced from the surface such that a wall portion of the body portion is defined between the surface and each of the plurality of pockets, and wherein each of the plurality of magnets is positioned in a respective one of the plurality of pockets.

8. The apparatus of claim 7 , wherein the wall portion is less than 0.05 inches thick.

9. The apparatus of claim 8 , wherein the wall portion is about 0.02 inches thick.

10. The apparatus of claim 6 , wherein the body portion includes a plurality of pockets formed therein, and wherein each of the plurality of magnets is positioned in a respective one of the plurality of pockets such that a surface of each of the plurality of magnets is exposed to at least partially define the surface of the body portion.

11. The apparatus of claim 1 , wherein the mounting shaft and the plurality of magnets has a concentricity of about 0.004 inches or smaller.

12. The apparatus of claim 1 , wherein the body portion is made of a material having low permeability.

13. The apparatus of claim 12 , wherein the body portion is made of one of aluminum and austenitic stainless steel.

14. The apparatus of claim 1 , wherein the magnetic tool further includes at least one flux concentrator.

15. The apparatus of claim 1 , wherein the magnetic arrangement includes a plurality of regions each having a north-south axis, the magnetic arrangement being arranged such that a north-south axis of each of the plurality of regions extends in at least one of a generally radial direction and a generally axial direction.

16. The apparatus of claim 1 , wherein the magnetic arrangement includes a plurality of regions each having a north-south axis, the magnetic arrangement being arranged such that a north-south axis of each of the plurality of regions extends in a generally circumferential direction.

17. The apparatus of claim 1 , wherein the workpiece holder electrically isolates the workpiece from ground.

18. The apparatus of claim 1 , wherein the workpiece holder supports the workpiece in a manner that accommodates thermal expansion of the workpiece.

19. The apparatus of claim 1 , wherein the workpiece holder supports the workpiece at a distance spaced from the surface of the magnetic tool, the distance being less than about 0.07 inches.

20. The apparatus of claim 19 , wherein the distance is about 0.02 inches to about 0.06 inches.

21. The apparatus of claim 1 , wherein the magnetic arrangement defines a sufficient number of magnetic poles (nP) and the drive arrangement rotates the magnetic tool relative to the workpiece holder at a sufficient speed (RPM) to achieve a frequency of at least 5 kHz according to the equation Hz=(nP*RPM)/60.

22. The apparatus of claim 21 , wherein the frequency is between 5 kHz and 21 kHz.

23. The apparatus of claim 1 , wherein the magnetic arrangement defines a surface profile of a desired shape corresponding to a desired case hardening profile for the workpiece.

24. The apparatus of claim 1 , wherein the magnetic arrangement defines a surface profile of a desired shape corresponding to a surface profile of the workpiece.

25. The apparatus of claim 1 , wherein the magnetic arrangement includes a member that is magnetized to include a plurality of magnetic regions, the magnetic regions defining the regions of alternating polarity.

26. The apparatus of claim 25 , wherein the magnetized member is a ring connected to the body portion, the ring defining the surface.

27. The apparatus of claim 1 , further comprising an eddy current conduit positioned adjacent the surface and configured to conduct eddy current from the magnetic tool to a surface of the workpiece.

28. The apparatus of claim 27 , wherein the eddy current conduit includes a lamination of silicon steel.

Assignees

• Timken Co

Inventors

• Fitch Stephen B
• Mills Jerry
• Stuehr William
• Gadus John
• Johnson Stephen P

Classifications

• C21D1/42

  Induction heating · CPC title

• C21D9/0062 Primary

  Heat-treating apparatus with a cooling or quenching zone · CPC title

• H05B6/405

  for heating gear-wheels · CPC title

• H05B6/101

  for local heating of metal pieces · CPC title

• Y02P10/25

  Process efficiency · CPC title