Electric Induction Heating of a Rail Head with Non-Uniform Longitudinal Temperature Distribution
A method is provided for making the longitudinal temperature distribution of the bulbous end of a longitudinally oriented workpiece, such as a rail's head, generally uniform when the head has a non-uniform longitudinal temperature distribution. A combination of crown and skirt electric inductors is used to achieve the generally uniform temperature distribution by modulating the magnetic field intensity produced by current flow through one or more of the combination of crown and skirt inductors as required for the non-uniformly heated regions of the rail's head.
This is a divisional application of application Ser. No. 12/194,774, filed Aug. 20, 2008, which application claims the benefit of U.S. Provisional Application No. 60/971,756, filed Sep. 12, 2007, both of which applications are hereby incorporated herein by reference in their entireties.
FIELD OF THE INVENTIONThe present invention relates to achieving generally uniform rail head temperature along the length of a railroad rail by electric induction heating when the rail head initially has a non-uniform longitudinal temperature distribution.
BACKGROUND OF THE INVENTIONRails used in the construction of railroad track require heat treatment to withstand metallurgical failure in normal use.
One object of the present invention is to provide apparatus for, and a method of, making the cross sectional temperature of a rail's head generally the same throughout the entire length of the rail by electric induction heating after the rail exits a hot rolling mill and before the rail is subjected to a quench process.
BRIEF SUMMARY OF THE INVENTIONA method is provided for making the cross sectional temperature of a rail's head generally uniform for the entire length of the rail when the cross sectional temperature is non-uniform for the length of the rail. Combinations of inductors are used to inductively heat sections of the rail's head and achieve the generally uniform cross sectional temperatures for the entire length of the rail. By modulating the magnetic field intensity produced by current flow through one or more of the combinations of inductors, temperatures within regions of the head along the longitudinal length of the rail can be affected to achieve the generally uniform cross sectional temperatures.
In another aspect the present invention is a method of electric induction heating the bulbous end of a longitudinally oriented workpiece, such as the rail head of a rail, with at least one crown inductor and an at least one skirt inductor. The crown inductor has a central longitudinal section, and right and left flank longitudinal sections. The right and left flank longitudinal sections each have a length shorter than the length of the central longitudinal section, and are located on opposing sides of the central longitudinal section. The central longitudinal section and right and left flank longitudinal sections are interconnected in different configurations to form the crown inductor. The skirt inductor comprises opposing right and left side skirt inductor sections. The right and left side skirt inductor sections are interconnected in different configurations to form the skirt inductor.
In another aspect the present invention is a method of electric induction heating the bulbous end of a longitudinally oriented workpiece, such as the head of a rail, wherein at least the bulbous end of the workpiece is electrically conductive. In one electric induction heating process of the invention, the workpiece is passed through at least one crown inductor and at least one skirt inductor, with the bulbous end oriented beneath the crown inductor and between the skirt inductor. The crown inductor comprises a central longitudinal section under which the top of the bulbous end passes through, and right and left flank longitudinal sections within which the flanks of the bulbous end passes though. The skirt inductor comprises opposing right and left side skirt inductor sections through which the sides of the bulbous end passes adjacently through. Alternating current power is applied to the crown inductor and the skirt inductor to generate a magnetic field around the at least one crown and skirt inductors so that magnetic flux couples with the electrically conductive bulbous end to induce heating by eddy current. In another electric induction heating process of the invention, the workpiece may be kept stationary while the crown and skirt inductors move over and around the sides of the bulbous end of the workpiece. In another electric induction heating process of the invention, a combination movement of the workpiece and at least the crown or skirt inductor may be used.
The above and other aspects of the invention are set forth in this specification and the appended claims.
The appended drawings, as briefly summarized below, are provided for exemplary understanding of the invention, and do not limit the invention as further set forth in this specification.
In this non-limiting example of the invention, because of the physical layout, rail 90 moves to induction heating station 86 with the trailing end 90″ of the rail leading the leading end 90′ of the rail. The induction heating station comprises a combination of inductors that are used to inductively heat the cross section of the rail's head to a uniform temperature along its entire length, as further described below, when it enters the induction heating station with a non-uniform temperature along its entire length.
In the drawings an orthogonal space is defined by X, Y and Z axes as illustrated by the diagrams in the drawings for convenience only, and is not intended to be restrictive of the invention.
Each inductor in the induction heating station is supplied ac power from one or more suitable power sources. As required for a particular application, each inductor may be supplied power from a separate source, or a group of inductors may be supplied power from a single source. Power may be supplied directly from the source, or via intermediate circuit components, such as a voltage drop transformer, or power matching transformer. The magnitude of output power (voltage) from a source to an inductor may be kept constant or varied during the induction heating process. The electrical frequency of the output from a source to an inductor may be kept constant or varied during the induction heating process, for example, to vary the depth of penetration of magnetic flux into the region of the rail's head.
Various types of control systems may be used to control the output parameters (for example, power (voltage) and/or frequency) of the one or more power sources as the length of a rail (rail's head) proceeds through the inductors comprising the induction heating station. For example, one or more rail head temperature readings (for example with a pyrometer) may be accomplished prior to the rail entering the induction heating station. These readings may be compared with stored data in a computer processing system that analyzes the readings and continuously adjusts the required output parameter(s) of the one or more power sources. Computer analysis and stored data may be based upon prior trial runs for rails of different dimensions and values of the output parameter(s) that achieve the required uniform temperature of the rail's head.
In other examples of the invention, acquisition of the non-uniform rail head temperature profile in the +X direction of successive rails moving to the quench station may be accomplished by scanning the rail as it moves past one or more temperature detectors, such as pyrometers 81, 83 and/or 85, in one or more of the de-scaling, cooling/translation, and/or the induction heating stations shown in
The acquired temperature readings (data) may be stored in a suitable memory device and used in an algorithm (executed by software) in a computational device (such as a computer processor). The output of the algorithm can be used to modulate the time that the magnetic field intensity supplied from current flow in the utilized crown and skirt inductors, either individually or in combination, as the rail passes through the inductors after, or during, acquisition of the temperature data. For example if the acquired (measured) temperature at a point along the length, Lr, of the rail in the crown, skirt or lower jaw region is lower than the temperature desired for the optimum metallurgical change during quenching, the algorithm would calculate the required increase in the magnetic field intensity at the time that the point passed under the respective crown and/or skirt inductors. This increase in magnetic field intensity would have the effect of eliminating the non-uniform temperature profile as shown, for example, in
In other examples of the invention one or more temperature sensing devices can be installed along the length of the induction heating station to dynamically sense the head's temperature so that output parameter(s) of the one or more power supplies can be adjusted as the rail's head proceeds through the induction heating station.
In other examples of the invention the system may be adaptively adjusted by measuring the temperature at one or more locations along the length of the rail's head after exiting the induction heating station, identifying any regions of non-uniform temperature reading, and adjusting the output parameters of the one or more power sources to correct the non-uniform temperatures for the next rail entering the induction heating station to be inductively heated.
Each inductor may be air cooled, or cooled by circulating a cooling medium, such as a liquid or gas, either through the inductor (for example, if the inductor has a hollow passage) or around the inductor. An inductor may be packaged in a closed container, except for entry and exit passages for the rail or head, and a cooling medium may be circulated through the closed container.
In other examples of the invention, an inductor may be a combination crown and skirt inductor that can comprise, for example, the combination of a crown inductor's central section and one or more side sections of a skirt inductor, or the combination of a crown inductor's central and flank section(s) and one or more side sections of a skirt inductor.
In some examples of the invention, the crown and/or skirt inductors may be permanently located over and around a rail's head as the rail is advanced through the induction heating station. In other example of the invention one or more of the crown and/or skirt inductors may be moveable, for example, by mounting one or more of the inductors on a carriage 30 as illustrated in
Carriage 30 in
Carriages 30 may optionally be used with each of the inductors identified in the arrangement illustrated in
A sensor may be suitably positioned to determine if a physical feature of a rail approaching inductor, Icar, will make abnormal contact with the inductor if it was allowed to pass under the inductor in its present position. If such determination is made, the vertical drive apparatus can be used to raise the inductor and clear the impending abnormal contact.
In the above example of the invention, the rail is moved through the induction heating station (in the X direction) while the inductors are kept in position (relative to the X direction). In other examples of the invention, a rail may be kept stationary and the inductors making up the induction heating station may move over and around the rail's head (in the X direction), or alternatively a coordinated movement of both the rail and one or more of the inductors making up the induction heating station may be utilized to inductively heat the rail's head.
While the above examples of the invention make the cross sectional temperature of the rail's head generally the same for the entire length of the rail after exit from a hot rolling mill, the invention is useful, and can be applied, for making the cross sectional temperature of the rail's head, or similarly configured workpiece, generally the same for the entire length of the workpiece when said cross sectional temperature is non-uniform along the entire length of the workpiece prior to the induction heat treatment process of the present invention.
A similarly configured workpiece may be a longitudinally oriented workpiece having a bulbous end similarly to that of the head of the rail. Only the bulbous end of the workpiece need be electrically conductive for application of the present invention.
The above examples of the invention have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the invention has been described with reference to various embodiments, the words used herein are words of description and illustration, rather than words of limitations. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein; rather, the invention extends to all functionally equivalent structures, methods and uses. Those skilled in the art, having the benefit of the teachings of this specification, may effect numerous modifications thereto, and changes may be made without departing from the scope of the invention in its aspects.
Claims
1. A method of electric induction heating of a bulbous end of a longitudinally oriented workpiece, wherein at least the bulbous end is electrically conductive, the method comprising:
- alternately passing the longitudinally oriented workpiece through an at least one crown inductor and an at least one skirt inductor with the bulbous end oriented beneath the at least one crown inductor and between the at least one skirt inductor, the at least one crown inductor comprising a central longitudinal section under which the top of the bulbous end passes through, and a right flank longitudinal section and left flank longitudinal section within which the flanks of the bulbous end passes though, the at least one skirt inductor comprising opposing right and left side skirt inductor sections which the sides of the bulbous end passes through; and
- applying alternating current power to the at least one crown inductor and the at least one skirt inductor to generate a magnetic field around the at least one crown inductor and the at least one skirt inductor so that magnetic flux couples with the electrically conductive bulbous end to induce heating by eddy current.
2. The method of claim 1 further comprising moving at least one of the at least one crown inductor or the at least one skirt inductor while alternately passing the longitudinally oriented workpiece through the at least one crown inductor and the at least one skirt inductor.
3. The method of claim 1 wherein the right flank longitudinal section and the left flank longitudinal section of at least one of the at least one crown inductor each having a length shorter than the length of the central longitudinal section of the at least one of the at least one crown inductor and are disposed on opposing sides of the central longitudinal section.
4. The method of claim 3 wherein the central longitudinal section of the at least one of the at least one crown inductor has an opposing first and second central section ends, the right flank longitudinal section has an opposing first and second right flank section ends, the left flank longitudinal section has an opposing first and second left flank section ends; the first right flank section end being connected to the first central section end by a first connecting segment, and the first left flank section end being connected to the second central section end by a second connecting segment, with the applied alternating current power connected between the second right flank section end and the second left flank second end.
5. The method of claim 3 wherein the central longitudinal section of the at least one of the at least one crown inductor comprises a first partial central section having an opposing first and second, first partial central section ends, and a second partial central section having an opposing first and second, second partial central section ends, the right flank longitudinal section having an opposing first and second right flank section ends, the left flank longitudinal section having an opposing first and second left flank section ends, the first end of the first partial central longitudinal section being connected to the first end of the right flank section, the first end of the second partial central section being connected to the first end of the left flank section, the second ends of the first and second partial central sections being located near each other, with the applied alternating current power connected between the second ends of the right flank and second partial central sections, and the second ends of the left flank and first partial central sections so that instantaneous current flow is either through the right flank section and then through the first partial central section, and through the second partial central section and then through the left flank section, or through the first partial central section and then through the right flank section, and through the left flank section and then through the second partial central section.
6. The method of claim 3 wherein the right side skirt inductor section of at least one of the at least one skirt inductor comprises a first partial right side skirt inductor section and a second partial right side skirt inductor section, and the left side skirt inductor section of the at least one of the at least one skirt inductor comprises a first partial left side skirt inductor section and a second partial left side skirt inductor section; the first partial right side skirt inductor section having an opposing first and second, first partial right side skirt inductor section ends, the second partial right side skirt inductor section having an opposing first and second, second partial right side skirt inductor section ends, the first partial left side skirt inductor section having a first and second, first partial left side skirt inductor section ends, the second partial left side skirt inductor section having a first and second, second partial left side skirt inductor section ends, the first ends of the first partial right and left side skirt inductor section ends connected together by a first connecting segment, the first ends of the second partial right and left side skirt inductor section ends connected together by a second connecting segment, the second ends of the first and second partial right side skirt inductor sections located near each other, and the seconds ends of the first and second partial left side skirt inductor sections located near each other, a crossover section connecting the second ends of the second partial right side skirt inductor section and the first partial left side skirt inductor section, with the applied alternating current power connected between the second end of the first partial right side skirt inductor section and the second end of the second partial left side skirt inductor section.
7. The method of claim 3 wherein the right side skirt inductor section of at least one of the at least one skirt inductor having an opposing first and second right side skirt inductor ends, the left side skirt inductor section of the at least one of the at least one skirt inductor having an opposing first and second left side skirt inductor ends, the first ends of the right and left side skirt inductor sections located near each other, the first ends of the right and left side skirt inductor sections connected together by a crossover section, with the applied alternating current power connected between the second ends of the right and left side skirt inductor sections.
8. The method of claim 1 where in the cross sectional temperature profile of the bulbous section is non-uniform along the longitudinal length of the longitudinally oriented workpiece prior to alternately passing the longitudinally oriented workpiece through the at least one crown inductor and the at least one skirt inductor, further comprising adjusting the applied alternating current power to the at least one crown inductor or the at least one skirt inductor as the longitudinally oriented workpiece passes through the at least one crown inductor and the at least one skirt inductor so that the cross sectional temperature profile of the bulbous section is substantially uniform along the longitudinal length of the longitudinally oriented workpiece upon exiting the at least one crown inductor and the at least one skirt inductor.
9. The method of claim 8 further comprising:
- measuring the temperature of at least one point on the longitudinally oriented workpiece before alternately passing the longitudinally oriented workpiece through the at least one crown inductor and the at least one skirt inductor, or while the workpiece is passing through the at least one crown inductor and the at least one skirt inductor; and
- adjusting the intensity of the magnetic field by adjusting the applied power to the at least one crown inductor or skirt inductor, responsive to the measured temperature of the at least one point.
10. A method of electric induction heating of a bulbous end of a longitudinally oriented workpiece, wherein at least the bulbous end is electrically conductive, the method comprising:
- alternately moving an at least one crown inductor over the top of the bulbous end of the longitudinally oriented workpiece for at least a partial length of the longitudinally oriented workpiece, and an at least one skirt inductor around the side of the bulbous end of the longitudinally oriented workpiece for at least a partial length of the workpiece, the at least one crown inductor comprising a central longitudinal section positioned over the top of the bulbous end as the at least one crown inductor moves, and a right and left flank longitudinal sections between which the flanks of the bulbous end are positioned as the at least one crown inductor moves, the at least one skirt inductor comprising opposing right and left side skirt inductor sections between which the sides of the bulbous end are positioned as the at least one skirt inductor moves; and
- applying alternating current power to the at least one crown inductor and the at least one skirt inductor to generate a magnetic field around the at least one crown and skirt inductors so that magnetic flux couples with the electrically conductive bulbous end to induce heating by eddy current.
11. The method of claim 10 further comprising moving the longitudinally oriented workpiece through at least one of the at least one crown inductor or the at least one skirt inductor.
12. A method of electric induction heating of a rail head of a rail, wherein at least the rail head is electrically conductive, the method comprising:
- alternatively moving the rail alternately through an at least one crown inductor and an at least one skirt inductor or moving the at least one crown inductor and the at least one skirt inductor around the rail, or in combination, moving the rail alternately through the at least one crown inductor and the at least one skirt inductor and moving the at least one crown inductor and the at least one skirt inductor around the rail, so that the rail head is oriented beneath the at least one crown inductor and between the at least one skirt inductor, the at least one crown inductor comprising a central longitudinal section under which the crown of the rail head passes through, and a right flank longitudinal section and left flank longitudinal section within which the flange corner surfaces of the rail head passes though, the at least one skirt inductor comprising opposing right and left side skirt inductor sections which the sides of the rail head passes through; and
- applying alternating current power to the at least one crown inductor and the at least one skirt inductor to generate a magnetic field around the at least one crown inductor and the at least one skirt inductor so that magnetic flux couples with the electrically conductive rail head to induce heating by eddy current.
13. The method of claim 12 wherein the right flank longitudinal section; and a left flank longitudinal section of at least one of the at least one crown inductor each had a length shorter than the length of the central longitudinal section of the at least one of the at least one crown inductor and are disposed on opposing sides of the central longitudinal section.
14. The method of claim 13 wherein the central longitudinal section of the at least one of the at least one crown inductor has an opposing first and second central section ends, the right flank longitudinal section has an opposing first and second right flank section ends, the left flank longitudinal section has an opposing first and second left flank section ends; the first right flank section end being connected to the first central section end by a first connecting segment, and the first left flank section end being connected to the second central section end by a second connecting segment, with the applied alternating current power connected between the second right flank section end and the second left flank second end.
15. The method of claim 13 wherein the central longitudinal section of the at least one of the at least one crown inductor comprises a first partial central section having an opposing first and second, first partial central section ends, and a second partial central section having an opposing first and second, second partial central section ends, the right flank longitudinal section having an opposing first and second right flank section ends, the left flank longitudinal section having an opposing first and second left flank section ends, the first end of the first partial central longitudinal section being connected to the first end of the right flank section, the first end of the second partial central section being connected to the first end of the left flank section, the second ends of the first and second partial central sections being located near each other, with the applied alternating current power connected between the second ends of the right flank and second partial central sections, and the second ends of the left flank and first partial central sections so that instantaneous current flow is either through the right flank section and then through the first partial central section, and through the second partial central section and then through the left flank section, or through the first partial central section and then through the right flank section, and through the left flank section and then through the second partial central section.
16. The method of claim 13 wherein the right side skirt inductor section of at least one of the at least one skirt inductor comprises a first partial right side skirt inductor section and a second partial right side skirt inductor section, and the left side skirt inductor section of the at least one of the at least one skirt inductor comprises a first partial left side skirt inductor section and a second partial left side skirt inductor section; the first partial right side skirt inductor section having an opposing first and second, first partial right side skirt inductor section ends, the second partial right side skirt inductor section having an opposing first and second, second partial right side skirt inductor section ends, the first partial left side skirt inductor section having a first and second, first partial left side skirt inductor section ends, the second partial left side skirt inductor section having a first and second, second partial left side skirt inductor section ends, the first ends of the first partial right and left side skirt inductor section ends connected together by a first connecting segment, the first ends of the second partial right and left side skirt inductor section ends connected together by a second connecting segment, the second ends of the first and second partial right side skirt inductor sections located near each other, and the seconds ends of the first and second partial left side skirt inductor sections located near each other, a crossover section connecting the second ends of the second partial right side skirt inductor section and the first partial left side skirt inductor section, with the applied alternating current power connected between the second end of the first partial right side skirt inductor section and the second end of the second partial left side skirt inductor section.
17. The method of claim 13 wherein the right side skirt inductor section of at least one of the at least one skirt inductor having an opposing first and second right side skirt inductor ends, the left side skirt inductor section of the at least one of the at least one skirt inductor having an opposing first and second left side skirt inductor ends, the first ends of the right and left side skirt inductor sections located near each other, the first ends of the right and left side skirt inductor sections connected together by a crossover section, with the applied alternating current power connected between the second ends of the right and left side skirt inductor sections.
18. The method of claim 12 where in the cross sectional temperature profile of the rail head is non-uniform along the longitudinal length of the rail prior to alternatively moving the rail alternately through the at least one crown inductor and the at least one skirt inductor or moving the at least one crown inductor and the at least one skirt inductor around the rail, or in combination, moving the rail alternately through the at least one crown inductor and the at least one skirt inductor and moving the at least one crown inductor and the at least one skirt inductor around the rail, further comprising adjusting the applied alternating current power to the at least one crown inductor or the at least one skirt inductor as the rail passes through the at least one crown inductor and the at least one skirt inductor so that the cross sectional temperature profile of the rail head is substantially uniform along the rail upon exiting the at least one crown inductor and the at least one skirt inductor.
19. The method of claim 18 further comprising:
- measuring the temperature of at least one point on the rail before alternatively moving the rail alternately through the at least one crown inductor and the at least one skirt inductor or moving the at least one crown inductor and the at least one skirt inductor around the rail, or in combination, moving the rail alternately through the at least one crown inductor and the at least one skirt inductor and moving the at least one crown inductor and the at least one skirt inductor around the rail, or while alternatively moving the rail alternately through an at least one crown inductor and an at least one skirt inductor or moving the at least one crown inductor and the at least one skirt inductor around the rail, or in combination, moving the rail alternately through the at least one crown inductor and the at least one skirt inductor and moving the at least one crown inductor and the at least one skirt inductor around the rail; and
- adjusting the intensity of the magnetic field by adjusting the applied alternating current power to the at least one crown inductor or skirt inductor, responsive to the measured temperature of the at least one point.
Type: Application
Filed: May 24, 2015
Publication Date: Sep 10, 2015
Inventors: Peter Dickson (Flint, MI), Paul F. SCOTT (Farmington, CT)
Application Number: 14/720,813