CA1254953A

CA1254953A - Rail head inductor

Info

Publication number: CA1254953A
Application number: CA000496765A
Authority: CA
Inventors: Edward J. Rylicki
Original assignee: Chemetron Railway Products Inc
Current assignee: Chemetron Railway Products Inc
Priority date: 1984-12-04
Filing date: 1985-12-03
Publication date: 1989-05-30
Also published as: WO1986003646A1; EP0205464A1; EP0205464A4; JPS62500964A

Abstract

ABSTRACT OF THE INVENTION

A railroad rail head inductor raises the temperature of the top and sides of the head to austenizing temperatures without inducing thermal strains which generate horizontal kinks along the sides of the head. The inductor has an electrical conductor for carrying alternating current across the top and along the lateral sides of the rail head for concurrently inducing a magnetic flux in the top and sides of the rail head. Laminations of electrical steel about the conductor are disposed on both sides of the rail for concentrating the magnetic flux induced in the lateral sides of the rail head. Laminations may be provided about the conductor over the rail head for concentrating the magnetic flux concurrently induced in the top of the rail head.

Description

3 ~ Do c ke t 1 d~ 7 8 Rail Elead Inductor This invention relates to an inductor for heating railroad rail heads to austenizing temperatures and is particula{ly useful in heat treatments designed t~ harden the heads for extending the service life of the railsO

In such thermal hardening treatments, the rail heads are heated to temperatures of up to about 2000F and then quenched to develop a pearlitic metallurgical structure in the metal~ U.S. Patents NosO 49099,9~6 and 4,201,602 disclose apparatus for moving the heating source longitudinally along the rail head to progressively heat the headO Canadian Patent No, 888,671 and U.S. Patents Nos~ 39266,956 and 3,276,9~ disclose apparatus for longitudinally ~oving the ralls relative to stationary heat sourcesO Also, U.5.
Patents Nos. 2 7 070~889 and 2,103,716 disclose apparatus for heating stationary rails with stationary heating sourcesO
The high ~emperatures realized in these processes in~ariably generate subs~antial ~hermal stresses in the heacls which tend to horizontally deform the rails. To be acceptable however~ the hardened rails must be straight. In the I . ~

1 United States, railrod rails must at least meet the recommendations of the American Railway Engineering Association (AREA). The AREA Manual For Railway Engineering Specification 4-M-6 (1975) recommends that the lateral sides and top of the hardened rails should have a certain minimum hardness penetration pattern.
Also, Specification 4-2-6.1 (1983) recommends that the horizontal misalignment along the lateral side of the rail head should not exceed 0.030 inches in three feet. In additional to these and other technical considerations, economics requires that the rails must be heated (and then hardened) as quickly and efficiently as possible.
The inductor of the present invention rapidly and efficiently generates austenizing temperatures in rail heads which develop hardness patterns after quenching meeting the AREA specification. Standard cabon rails are heated by the inductor at speeds of up to 24 inches/minute and at heating efficiencies of about ~0%. The hardened rail heads are substantially straight and require very little (if any) horizontal restraightening to meet the AREA specification.
The rail head inductor has an electrical conductor adapted to carry al-ternating current across the top and along the lateral sides of the rail head for concurently inducing a magnetic flux in the top and sides of the rail head and focusing means disposed about the electrical conductor on both sides of the rail head for concentrating the magnetic flux concurrently induced in the lateral sides of the rail head. Preferably there is a second focusing means disposed about the portion of the electrical conductor extending across the rail head for concentrating the magnetic flux induced in the top oE the rail head as well~

Other features~ objects and advantages of the present inven~ion will become apparent as the following description of a presen.tly preferred embodiment thereof proceeds.

In the accompanying drawings:

Fig. l is a front elevation view showing the inductor of the present invention and a rail being heated below, ~ig. 2 is a rear elevation view of the inductor shown in F ig . l;

Fig. 3 is a bottom Yiew of ~he inductor shown in Fig. l;

Fig~ 4 is an end view of the inductor shown in Fig. 1 taken along line IV-IV;

Fig. 5 is a sectional view of the inductor shown in Fig. 1 taken along line V-V;

~ ig. 6 is a seotional elevation view of the inductor shown in Fig. 1 taken along line VI-VI;

Fig. 7 is a sectional elevation view of the inductor shown in Fig. 1 taken along line VII-VII;

Fig. 8 is a sectional side elevation view of the inductor shown in Fig. 1 taken along line VIII-VIII;

Fig. ~ is a representation of the flow of electrical current through the inductor of Fig. l; and Fig. 10 illustra~es the rail head hardness pattern used in the railroad industry.

The drawings illustrate an inductor 10 which is about two to three feet in overall length (including guide rollers) for progressively heating the upper portion of the head 52 of a longitudinally moving rail 50 which may be from about 39 feet long in the case of a nominal rail length up to about 1660 feet long in the case o a welded string of track. The inductor can sufficiently heat standard weight rails moving at speeds of 24 inches per minute and modular arrangements of these inductors will heat rails moving at speeds of up to 120 or 180 inches per minute. Alternatively, the rail could be stationary and an inductor such as that illustrated could be longitudinally moved along the rail.
Also~ both inductor and rail could be stationary during the hea~ing step, but this would require an inductor unit extending the entire length of the rail.

As is illustrated in Figures 1 and 2, the induc~or 10 is suspended over a longitudinally moving rail 50 from a horizontal base member 20 which is supported by a vertical board 12 having transv~rse ribs 14. The vertical board 12 is longitudinally immoveably held by a -frame (not shown).
Preferably the base member 20 is fabricated of refractory L ~

sheet material such as sheet known in the trade as ~zircar~
and the board 12 and ribs 14 are fabricated of a laminated phenolic material. The base member 20 and the board 12 are fastened together by screws 16 and to ribs 14 by screws 18. The base member 20 has posts 24 of refractory material such as tha~ known as ~transite" depending from its bot~om surface 22 and ~astened thereto with screws 26 or other ~uitable fasteners for providing additional support Eor the inductor 10.

1~ The inductsr 10 generally comprises an electrical conductor 30 and focusing means 40 and 41 disposed about ~he eonductor 30. The details of the inductor 10 may be most clearly seen in Flgures 3-8~ The general ronfiguration of conductoE 30 may be most readily seen in Figure 9. Tha 15 depicted conductor 30 is a brazed 1 x 1/2 inch rectangular copper tube having a 0.125 inch thick wall with the one inch dimension generally facing the rail 50~

The focusing means 40 disposed at the sides of the rall head 52 and second focusing means 41 disposad above the 20 rail head 52 about the conductor 30 generally comprise stacked laminationR of electr.ical steel such as Qilicon-iron al70y5 sold under the name "Magnesil~. Each lamination i5 an electrically insulated "C~ shaped section having 1~4~ x 1/2~ armq ex~ending from a 1/4a x 1 1/2" cen~ral strlp and 25 a thickness o~ ".007~ Each lamination al50 ha~ copper keepers 42 on ei~her c;ide for mechanical support and one * Trade Mark mica spacer per inch or breaking the electrical conductivity through the stack, The focusing means 40 and 41 are preferably bonded to the electrical conductor 30 by a thermal adhesive.
Preferably the conductor 30 and focusing means 40 and 41 are coated with a ceramic material. Substantially identical opposed pairs of laminated stacks are located along the sides of the rail head 52 so that substantially equal amounts of heat are induced in the cross section of the rail head to minimize thermal stresse~ tending to hori~ontally 10 kink the rail.

The inductor 10 is fastened to base 20 by bolts 23 which are soldered to the conductor 30 on both sides of focusing means 40. Additional support is provided by soldered bolts 25 which fasten the vertical lengths of 15 conductor 30 to posts 24.

The terminals 34 of conductor 30 are mechanically supported by vertical board 12~ Each terminal 34 is silver soldered to a vertical plate 37 having a bracket 39 fastened ~o the board 12 by a screw 13. A mica sheet (not shown) is disposed between the vertical plates 37 to electrically insulate the plates and the terminal bolt 35. As may be seen in Fig. 8, the conductor 30 is further supported on the undercu~ portion 25 of posts 24. Also, a mica sheet 31 is disposed between the adjacent lengths of conductor 30 for electrically insulating these lengths.

The conductor 30 is preferably cooled by water or other suitable fluid flowing within the rectangular tubeq As the drawings illustrate, two inlet por ts 36 near the conductor terminals 34 and two outlet ports 38 provide coolant to and Erom the conductor 30.

At each end of the inductor lO are plates 44 secured to the bottom surface 22 of the horizontal base member 20 by bolts 46 or other suitable fasteners for supporting depending guide rollers which protect the inductor 10 from ~he rail 50. As may be most clearly seen in Fig. 4 horizontal rollers 48 protect the inductor unit from vertical movements of the rail which could for example result from a crowning type operation. Vertical rollers 49 extend downwardly along the sides of the rail and protect the inductor unit rom lateral movement of the rail . An insulating board (not shown) may be utilized on the plate 44 at the exit of the inductor unit to protect the plate 44 from temperatures of about 2000 F. The rollers 48 and 49 at the entering end are kept sufficiently cool by the atmosphere.

In a demonstration test of the inductor lO shown in the drawings, the terminals 34 of the conduct 30 were energized with 3 KHz current at a power output of about 340 E~ to heat a carbon steel weighing about 132 lbs. per yard moving along its longitudinal axis at a speed of 24 inches per minute in a hardening process. The original structure of the rail head was coarse grained pearlite and the resulting structure was fine grain pearlite which indicates that the metal was heated to austeni~ing temperatures before the L~ ~ 5 ~3 quench. The Rc hardness of the rail along the segments of the rail head identified in Fig. 10 were as follows:
Dist~ from Surface 16 ths AO BO CO DO E0_ _ _

2 39 40 39 39 40

3 39 40 39 39 39 3~ ~0 3~ 39 3 3~ 39 37 ~9 38 lo 6 37 39 37 3~ 38 8 36 38 3~ 3~ 37 1~ 35 3~ 30 37 35 12 35 36 2~ 3~ 32 13 33 36 ~5 36 29 1~ 30 35 35 28 -29 35 34. 27 17 26 3~ 29 lg 28 27 ~7 Fig. 10 is in accordance with AREA Specifications 4-M~6 which defines segment AE to be 7/8~ below the ball of the rail head and points B and D to be 5/8 il above segment A~ D
The SpeciEication recommends an aim hardness pattern as ~ollows:
Results of ~bove Seqment Depth Brinell Rockwell C Test ~o 6/16~ 321 3~ 37 BO and DO ~ 6 9' 321 34 q 4 37 AO and EO 9/16~9 321 34,4 36 A visual inspection of ~he rail indicated that the rail would only require touch-up restraightening, if any. This test indicates that the rails easily mee~t t:he AREA

Specif ication .

While a preferred embodiment of the inductor of ~e present invention has been shown and described above, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied within the scope of the following claims.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows

1. An inductor for heating the head of a railroad rail in a head hardening heat treatment comprising:
an electrical conductor adapted to be spaced from the top and lateral sides of the rail head for carrying alternating current across the top and along the lateral sides of the rail head for concurrently inducing a magnetic flux in the top and sides of the rail head; and focusing means disposed about the electrical conductor on both lateral sides of the rail head for concentrating the magnetic flux induced in the lateral sides of the rail head.

2. The inductor of claim 1 further comprising a second focusing means disposed about the portion of the electrical conductor extending across the rail head for concentrating the magnetic flux concurrently induced in the top of the rail head.

3. The inductor of claim 1 wherein the focusing means further comprises laminations of electrical steel.

4. The inductor of claim 1 further comprising means for longitudinally moving the rail head relative to the inductor.

5. The inductor of claim 1 further comprising means for moving the inductor longitudinally of the rail head.

6. A method of heating the head of a railroad rail to austenizing temperatures in a head hardening heat treatment comprising the steps of:
positioning a railroad rail in predetermined relation to an inductor having an electrical conductor such that the top and lateral sides of the rail head are in predetermined magnetic relationship with said conductor, said inductor including focusing means disposed about the electrical conductor on both lateral sides of the rail head, and effecting relative longitudinal movement between the rail head and said inductor.

7. The method of claim 6 wherein said step of effecting relative longitudinal movement between the rail head and said inductor is carried out to obtain relative speeds of at least about 120 inches per minute.

8. The method of claim 7 wherein said step of effecting relative longitudinal movement between the rail head and said inductor effects relative speeds of about 180 inches per minute.