INDUCTOR FOR HEATING RAILROAD RAILHEADS

Abstract: A railroad rail head inductor (10) raises the temperature of the top and sides of the head (52) to austenizing temperatures without inducing thermal strains which generate horizontal kinks along the sides of the head. The inductor (10) has an electrical conductor (30) for carry alternating current across the top and along the lateral sides of the rail head (52) for concurrently inducing a magnetic flux in the top and sides of the rail head (52). Laminations of electrical steel (40) 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 (52). Laminations (41) may be provided about the conductor (30) over the rail head (52) for concentrating the magnetic flux concurrently induced in the top of the rail head (52).

Description: Inductor For Heating Railroad Railheads This invention relates to an inductor for heating railroad rail heads to austenizing temperatures and is particularly useful in heat treatments designed to harden the heads for extending the service life of the rails. In such thermal hardening treatments, the rail heads are heated to temperatures of up to about 2000°F and then quenched to develop a pearlitic metallurgical structure in the metal. U.S. Patents Nos. 4,099,996 and 4,201,602 disclose apparatus for moving the heating source longitudinall along the rail head to progressively heat the head. Canadian Patent No. 888,671 and U.S. Patents Nos. 3,266,956 and 3,276,924 disclose apparatus for longitudinally moving the rails relative to stationary heat sources. Also, U.S. Patents Nos. 2,070,889 and 2,103,716 disclose apparatus for heating stationary rails with stationary heating sources. The high temperatures realized in these processes invariably generate substantial thermal stresses in the heads which tend to horizontally deform the rails. To be acceptable however, the hardened rails must be straight. In the United States, railroad 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 along the segment lines shown in Fig. 10. 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 carbon rails are heated by the inductor at speeds of up to 24 inches/minute and at heating efficiencies of about 40%. 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 alternating current across the top and along the lateral sides of the rail head for concurrently inducing a agnetic 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 of the rail head as well. Other features, objects and advantages of the present invention will become apparent as the following description of a presently preferred embodiment thereof proceeds. In the accompanying drawings: Fig. 1 is a front elevation view showing the inductor of the present invention and a rail being heated below; Fig. 2 is a rear elevation view of the inductor shown in Fig. 1; Fig. 3 is a bottom view of the inductor shown in » Fig. 1; 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; Fig. 6 is a sectional 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. 9 is a representation of the flow of electrica current through the inductor of Fig. 1; and Fig. 10 illustrates 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 of 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 heating step, but this would require an inductor unit extending the entire length of the rail. As is illustrated in Figures 1 and 2, the inductor 10 is suspended over a longitudinally moving rail 50 from a horizontal base member 20 which is supported by a vertical board 12 having transverse ribs 14. The vertical board 12 is longitudinally immoveably held by a frame (not shown). Preferably the base member 20 is fabricated of refractory -6- 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 that known as "transite" depending from its bottom surface 22 and fastened thereto with screws 26 or other suitable fasteners for providing additional support for the inductor 10. The inductor 10 generally comprises an electrical conductor 30 and focusing means 40 and 41 disposed about the conductor 30.- ' The details of the inductor 10 may be most clearly seen in Figures 3-8. The general configuration of conductor 30 may be most readily seen in Figure 9. The 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 rail head 52 and second focusing means 41 disposed above the rail head 52 about the conductor 30 generally comprise stacked laminations of electrical steel such as silicon-iron alloys sold under the name "Magnesil" . Each lamination is an electrically insulated "C" shaped section having 1/4" x 1/2" arms extending from a 1/4" x 1 1/2" central strip and a thickness of ".007". Each lamination also has copper keepers 42 on either side for mechanical support and one mica spacer per inch for breaking the electrical conductivity through the stack. The focusing means 40 and 41 are preferabl 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 stresses tending to horizontally 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 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 to 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 undercut 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 tube. As the drawings illustrate, two inlet ports 36 near the conductor terminals 34 and two outlet ports 38 provide coolant to and from the conductor 30. At each end of the inductor 10 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 the 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 downwardl along the sides of the rail and protect the inductor unit from 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 10 shown in the drawings, the terminals 34 of the conduct 30 were energized with 3 KHz current at a power output of about 340 KW 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 austenizing temperatures before the quench. The Re hardness of the rail along the segments of the rail head identified in Fig. 10 were as follows: Dist. from Surface lδths AO BO CO DO EO 1 38 39 38 38 38 2 39 40 39 39 40 3 39 40 39 39 39 4 38 40 38 39 38 5 38 39 37 39 38 6 37 39 37 38 38 7 37 39 35 38 37 8 36 38 34 38 37 9 36 38 31 38 36 10 35 38 30 37 35 11 35 37 28 37 33 12 35 36 26 36 32 13 33 36 25 36 29 14 30 35 35 28 15 29 35 34 27 16 27 34 31 17 .26 32 29 18 30 29 19 28 27 20 27 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" above segment AE. The Specification recommends an aim hardness pattern as follows : Results of Above Segment Depth Brinell Rockwell C Test CO 6/16" 321 34.4 37 BO and DO 11/16" 321 34.4 37 AO and EO 9/16" 321 34.4 36 A visual inspection of the rail indicated that the rail would only require touch-up restraightening , if any. This test indicates that the rails easily meet the AREA Specification. hile a preferred embodiment of the inductor of the 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: HAT IS CLAIMED IS: 1. A rail head inductor comprising: an electrical conductor adapted to carry 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 rail head 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 rail head inductor of Claim 1 wherein the focusing means further comprises laminations of electrical steel .

Inventors: RYLICKI EDWARD J, RYLICKI, EDWARD, J.
Applicants: CHEMETRON RAILWAY PROD, CHEMETRON RAILWAY PRODUCTS, INC.
Application year: 1985
Main classification: H05B6
IPC codes: C21D1, C21D9, H05B6