US2292601A - Method of and apparatus for the aluminothermic welding of rails - Google Patents

Description

A118. 1 E. F. BEGTRUP 2,292,601

METHOD OF AND APPARATUS FOR THE ALUMINO-THERMIC WELDING 0F RAILS Filed March 17, 1939 I 2 Sheets-Sheet 1 mmvrolg fli 7 0 (,3 A 2 :ATTORNEYS.

8- 1942- 1:. F. BEGTRUP 2,292,601 METHOD OF ANb AP I ARATUS FOR THE ALUMINO-THERMIC WELDING OF RAILS Filed March 17, 1939 v2 Sheets-Sheet 2 N 2 N R HT :1 L Q III I ll . "F15 zINVENTOk.

a 0. Y jp ATTORNEYS.

Patented Aug. 11, 1942 METHOD OF AND APPARATUS FOR THE ALUMINOTHERMIC WELDING OF RAILS Edward F. Begtrumllersey City, N. J., assignor to 'Metal & Thermit Corporation, NewYork, N. Y.,

a corporation of New Jersey Application March "17, 1939, Serial N0. 262,559

15 Claims.

This invention relates to method -of andapparatus for the alumino-thermic welding of rails; and it comprises a method of welding rails by the alurnino-thermic method whichcomprises abutting the ends of two rails to be welded in such fashion that agap is left between the bases and webs of said rails to receive molten a'luminothermic metal, constructing a mold around the resulting joint having a fusion collar-defining space surrounding the webs and bases of said rails and including passageways extending substantially horizontally beneath the rail heads on either side 'of the joint and on either side of the rail heads; said passageways terminating -in constricted channels spaced slightly'from said joint and extending upwardly following the contour-of the rail heads; preheating said joint by passing heated gases upwardly through "said collar-defining space, through said horizontal passageways, upwardly through said constricted channels and then horizontally over the tops of the rail heads, then pouring an alumino-thermic charge into said mold in such manner that said collar-defining space and said horizon-tal passageways are filled with. molten 'alumino-thermic metal; said metal being passed upwardly through said constricted channels to'substantially fill the same; flowing alumino-thermic slag over the tops of the rail heads, and then forcing the rail heads together to produce pressure welding 'of said heads; said process being usually conducted in such fashion that the slag is initially contacted with the rail heads on either side of said joint before contacting the joint itself and said collar-defining space usually being so shaped as to produce a wide base collar around the bases or feet of the rails and a wide head collar beneath the rail heads, these wide fusion collars being connected by a substantially narrower web collar extending along the webs of 'the 'rails. This invention also includes the mold whi'chis used in the described welding process, said mold being provided with a cope section having pouring openings on either side of the rails communicating with capacity chambers which extend downwardly on either side of said rails to a'point below the rail heads and which communicate with the above described fusion collar-defining space and constricted channels by means of-substantially horizontal cross pouring gates at a point which is below the railvheads and advantageouslyspaced substantially half way between the tops and the feet of the rails; all as more fully hereinafter set forth and as claimed.

rails has proven to haveadvantages over the use offull fusion welding methods in which the rails are joined-by-cast steel derivedfrom the aluminothermic charge. vIn the combined method the feet of the rails are fusion welded and this fusion weld in prior art methods has extended upwardly to include most of the webs of the rails but has stoppeda short distance below the rail heads. The rail heads and the upper portions of the webs have been united by pressure welding after these parts have beenlheated to pressure welding temperatures by contact with superheated alumino-thermic slag.

One method which has been used vin the pressure-fusion welding of rails is described and claimed .in my prior patentQReissue No. 17,671. In this method the feet and the lower portions of the webs .of two rails to be welded are trimmed away slightly at their ends and the railvhea'ds are faced off in such fashion that, when the rails "are abutted, the rail heads and the'upper portions of the webs are flush while the lower portions of the webs and the feet of the rails are .spaced slightly to provide room for the alumino-thermic metal to flow therebetween. The mold, which is placed around the joint between therails, is provided with pouring gates and fusion collar-defining spaces on either .side of the rails. The pouring gates terminate in substantially horizontal passageways which-serve to direct the alumino-thermic charge into the collar defining spaces at a .point just below the heads of the rails. The alumino-thermic charge is introduced into the mold in such manner that the molten steel fills the collar-defining space up to a point somewhat below the rail .heads while the slag contacts with the underportions of the rail heads at the joint. The sides of the rail heads at the joint and a portion of their tops are protected from direct contact with the slag by means of mold projections but the slag flows around the rail heads on either side of .the joint and across the tops of the rails around and between the said mold projections. This slag serves to heat r the rail heads and the upper portions of the webs to pressure welding temperatures. The present invention represents, in some respects, an improvement upon that described in this prior patent.

Prior art methods used in the pressure-fusion welding of rails have possessed certain undesirable features. In using these methods it is sometimes found that the molten steel and slag flowing against the webs of the rails produce a The combined pressure-and fus'ion welding of 5 sloughing action which'causes undue fusion and washing away of the webs. The upper portions of the webs have frequently become overheated, especially at the boundary of the slag and weld metal. This has caused the introduction of local stresses and stress-raiser effects in the web at the vicinity of the steel level as well as resulting in low fatigue strength and at times shrinkcrack fiaws. It has also been found difficult to control the quantity of alumino-thermic charge in such manner that the desired level of molten steel is obtained reproducibly, owing to variable conditions encountered in the field, such as a varying width of gap between the bases and the lower portions of the rail webs, variations in the size of mold cavities, etc. In addition it has been found difiicult to produce the desired uniformity of heating throughout the rail heads which is required to produce a homogeneous weld. The present invention provides a solution of these difiiculties.

I have found that stronger joints and joints comparatively free from local stresses can be produced by means of a new method which combines several important advantages. In this method a wide fusion collar is formed to embrace the feet of the rails and a fusion collar of substantially the same width is formed beneath the rail heads on either side, these wide portions being joined by relatively narrower portions extending along the webs of the rails. The mold employed is formed with two pouring openings which communicate with capacity chambers positioned on either side of the rails, said capacity chambers extending downwardly to a point somewhat below the rail heads and terminating in cross pouring gates which communicate with a fusion collar-defining space at a point substantially midway between the tops and the bottoms of the rails. The fusion collar-defining space extends around the feet and the webs of the 1 rails at the joint and upwardly underneath the rail heads at which point it divides into substantially horizontal passageways extending a short distance on either side of the joint, said passageways terminating in constricted substantially vertical channels which follow the contour of the rail heads and are spaced from the joint on either side. The fusion collar-defining space has a width around the feet of the rails which corresponds substantially to the width of the said horizontal passageways while the collar-defining space which extends around the webs of the rails is substantially narrower.

The sides of the rail heads are protected from contact with the alumino-thermic charge, except at the described constricted channels, by means of mold projections. These mold projections are shaped in such manner that they form a slag basin extending along the tops of the rail heads as well as spillways for slag on either side of the rails. The said spillways connect the said slag basin with the described capacity chambers and are formed in such manner that, when the charge fills the capacity chambers, the slag overflows the spillways into the slag basin at points spaced from the joint on either side and then fiows towards said joint. The width of the slag basin in the direction of the axis of the rails advantageously corresponds substantially to the width of the fusion collar-defining space around the feet of the rails. These relative dimensions contribute to the efiiciency of the preheating and are at least partly responsible for the fact that less stresses are present in my welds than in those produced by prior art methods. The mold is also provided with the usual preheating gate and vent.

During preheating of the joint, the hot gases pass around the feet of the rails then upwardly through the described collar-defining passageways, through the horizontal passageways beneath the rail heads and then upwardly through the constricted channels around the faces of the rail heads and then horizontally beneath deflectional surfaces across the tread surfaces of the rails on both sides of the joint, finally passing out of the mold at the top. Owing to the fact that the gases are passed around and across the tread surfaces of the rails through the described constricted channels, the rail heads are preheated to a higher temperature than with prior molds and this heating is more uniformly distributed throughout the transverse cross-section of the rail. The heating gases pass through the described constricted channels at an increased velocity whereby the rate of heat transfer is increased at these points.

After preheating, the preheating gate and vent are closed and the alumino-thermic charge is introduced into the pouring basin in the cope section of the mold. The superheated metal falls to the bottom of the capacity chambers and flows through the cross pouring gates into the collardefining space around the feet and webs of the rails. The cross pouring gates direct the flow of preheated metal into the collar-defining space at its narrowest point and the width of these gates corresponds substantially to that of the gap between the webs and feet of the rails. It is thus evident that the flow of superheated metal is confined in such fashion between directional surfaces that it strikes the gap between the webs and hence there is little if any tendency for eddy currents to be set up which might cause sloughing away of the rail metal. Sufiicient aluminothermic charge is employed so that the molten weld metal fills the fusion collar-defining space and the cross pouring gates as well as extending some distance up into the capacity chambers. Since the cross pouring gates are filled with weld metal the slag is excluded from the fusion-collar defining space and is prevented from contacting the lower parts of the rails beneath the heads, a feature which is important in preventing slag inclusions in the weld metal, The capacity chambers are filled with slag and the slag, as it reaches the tops of these chambers, overflows the spillways on to the tops of the rail heads on either side of the joint and then flows towards the joint from either side.

The alumino-thermic metal and slag in the capacity chambers serve to produce a pressure head sufiicient to force the molten steel of the charge through the passageways beneath the rail heads and then through the constricted channels around the rail heads on either side of the joint. It will be noted that this molten steel passes a considerable distance while in contact with the rail heads through narrow passageways and during this procedure it becomes chilled substantially to the point of congelation. By the time this metal reaches the constricted channels which follow the contour of the rail heads it is so stiff and viscous that these channels are usually not completely filled with metal in spite of a pressure head tending to force the metal out of these channels and on to the tops of the rail heads. The final height reached by the metal in the constricted channels is substantially independent of the pressure head and is controlled by the length and cross section of the channels through which it passes. The chilled :metal in the .upper .parts .of the channels is cooled .sufiia ciently so .it does not weld to the rail heads. The height to which .the alumino-thermic metal rises in the constricted channels is not important since this 'has but little effect upon the weld, and since this height is automatically controlled by the dimensions of these channels, the height of the alumino-thermic :metal in the capacity chambers can be varied considerably without effect upon the weld. The important point is to provide sufficient :metal in the charge to cover the cross 'pouringgates thereby preventing the introduction of slag beneath the rail heads. It is therefore evident that, within limits, the width of the gap left between the webs and feet of the rails, the cross section of the collar-defining passageways and the quantityof the charge can all be varied considerably without injuriously affecting the weld. This is a new and important result in this art.

The slag which overflows the spillways on to the tops of the rail heads tends to heat the rail heads more or less uniformly owing to the fact that it first contacts the rail heads at points spaced from the joint. Since the heat is-not concentrated at the joint there is no danger of the rail heads fusing at this point. And owing'to the construction of the horizontal passageways beneath the rail heads, the fusion collar of the weld extends beneath the rail heads for a short distance on either side of the joint, the total width of this collar being substantially equal to the width of the fusion collar at the bases of the rails.

It has been found that the high heat developed in the lower parts of the rail heads by my process causes the fusion weld to extend upwardly for some distance into the rail heads. The line of fusion, as seen in a cross section of the weld, has a rounded high point in the com ter which tapers off to either side of the rail head. It is thus seen that my method produces the greatest possible full fusion area without bringing the rail tread surface to the melting point. The upper portions of the rail heads :are, of course, not fused during the weldingbpera tion. The resultant weld has a considerab y higher fatigue strength than prior pressurefusion welds and local stresses are sub-stantially eliminated.

My invention can be explained in somewhat greater detail by reference to the accompanying drawings which show several views of a mold and a welded joint within the purview of the present invention and illustrate how my process can be employed in practice. In this showing Fig. 1 is a transverse cross section through the rail and the mold, taken along the line :l.| of Fig. 2,

Fig. 2 i a longitudinal :section through the mold and the base of the rail, taken along the line 22 of Fig. 1,

Fig. 3 is a top or plan View of the mold and rail with the cope section or pouring basin :removed,

Fig. 4 is a horizontal section looking downwardly, taken along the line 4-i- .of Fig. 1. while Fig. 5 is a perspective view of oneof my welds after removal of the mold.

In the various figures like elements are designated by like reference characters. Referring particularly to Fig. l, the rails to be united are shown at R, the rails illustrated being of :the conventional T. type. The webs and feetof these rails are undercutat thejointas shown best in Figs. 2,3 and 4, to formagap X which'is *filled with alumino-thermic metal during the welding operation. The mold is showngenerally 'at M, this mold being provided at the top with a icope section or pouring basin P, the latter being supplied at either end with the pouring openings '0. The lower part of the moldis provided with-the usual preheating gate H and vent hole V. The mold cavity is of rather complicated structure and includes capacity chamber J on either side of the rails which receive the charge as it passes through the pouring openings'O. These capacity chambers extend downwardly to :a point somewhat below the heads of :the rails and terminate in cross pouring gates G on either side of "the rails. These pouring gates serve to conduct the molten steel of the charge into the fusion collardefining space shown generally at Z.

It will be noted from Fig. 2 that the width of the cross pouring gates corresponds substantially :to'the width of the gap left between the webs and the feet of the rails. The advantages of this structure have been pointed out previously. It will also be noted that the web fusion collar space is defined by the two substantially parallel mold sides W and W (Fig. 2) which form directional channels on either side of the rails at the cross pouring gates G, serving to prevent side wash of the rail ends. The web fusion collar space defined by these substantially parallel sidewalls is not substantially wider than the gap left between the webs of the rails.

It will be seen from Fig. 2 that the fusionco'llar-defining space divides into substantially horizontal passageways L which extend horizontally beneath the rail heads for some distance to either side of the joint and which terminate in substantially vertical constricted channels N which are spaced from the joint and conform to the gauge and offside faces of the rail heads. Above the constricted channels N there are provided the horizontal deflecting surfaces F which have the function of deflecting the heating across and in contact with the tread surfaces of the rails. The upper sections of the fusion collar-defining space and the channels are partly defined by the mold projections shown generally at 'I. 'These projections extend across the mold cavity on either ide of the rails and serve to separate the capacity chambers J from the slag basin s, the latter extending across the tops of the rails as shown in Fig. 3. The upper edges of the mold projections on either side of the rails have a central raised portion U at the joint which prevents the lag from overflowing from the capacity chambers directly on to the rail heads at the joint. The lower sections T of the upper edges of these mold projections form spillways for the slag which overflow the capacity chad bers into the slag basin S on either side of the joint and on either side of the rails and then flows towards the joint along the tops of the rails.

Fig. 5 shows one of my welds after removal of the mold-and after the excess st el has been -partially trimmed 'away. The base fusion cellar which extends around the feet of the rails is shown at A, while the head collar extending beneath the rail head is shown at Y. two portions are joined by the relatively narrower web collar B which extends along the webs of the rails. The fusion collar projection sh. at D extends upwardly along the side of the rail head and this is the portion which is formed by the constrictedchannels N shown in the other figures. These projection must, of course, be removed from the faces of the rails before the weld is completed, as shown at the left of the joint at Q in Fig. 5. As stated previously the upper portions of these projections are not welded to the rails and hence can usually be removed by a chisel. The lower portions are usually removed by a machining operation. A portion of the cast steel which formerly filled the cross pouring gate G of the mold is shown at C in Fig. 5. Any cast steel present in the capacity chambers J of the mold is attached to the projection C when the mold is removed from the weld. This excess metal has been broken off in the showing of Fig. 5. The knob E represents the metal which formerly filled the vent V of the mold.

The procedure which is employed in the making of a weld by the mold shown in the figures is believed to be evident from the preceding description. The first step in this operation is, of course, to cut back the webs and feet of the rails and to face off the heads in such manner that, when the rails are abutted, the rail heads will be flush while the webs and feet will be spaced apart about inch. After the rails are abutted in this manner the mold is constructed around the joint. The joint is preheated by the use of a blow torch which is applied at the preheating gate H. The gases pass around the webs and feet of the rails through the fusion collar-defining space, spreading beneath the rail heads to pass through the horizontal passageways L, then upwardly around and across the tops of the rail heads through the constricted channels N finally passing out at the top of the mold. The gases which pass through the cross pouring gates and upwardly through the capacity chambers serve to thoroughly dry out the mold. It is evident that the mold, during this preheating step, serves as a furnace for the heating of the joint. When the preheating is completed the preheating gate H and the vent V are plugged and the aluminothermic charge is tapped into the pouring basin P from the bottom of the usual crucible. The superheated steel of the charge passes through the capacity chambers, through the cross pouring gates from opposite sides, entering the fusion collar-defining space at points below the rail head, filling the space around the feet and the webs of the rails. Pouring is continued while the metal fills the cross pouring gates and rises through the horizontal channels L and enters the constricted channels N. The quantity of charge is advantageously so chosen that the metal present is sufficient to fill the capacity chambers a slight distance above the cross pouring gates. The slag of such a charge is suflicient in quantity to fill the capacity chambers and to overflow the spillways T into the slag basin S on top of the rails. This basin should be also filled with the slag.

As soon as the rail heads have reached pressure-welding temperatures, they are forced together in known manner to produce the desired pressure for the welding. After the mold is cooled somewhat it is removed from the welded joint. Then, after the projections D have been removed and after the tread and gauge surfaces have been faced off to remove the usual slight bulge at the joint, the weld is completed.

While I have described what I consider to be the best embodiments of my process it is evident that various modifications can be made in the specific procedures set out without departing from the purview of this invention. My welding method can be adapted to the welding of girder rails within the skill of the art and with only slight deviations from the procedures set forth. The method described for controlling the level of the steel in the weld zone is broadly applicable to the production of riser-less Welds, Whether or not these welds are of the pressurefusion type. My welding method is likewise applicable to the so-called insert welds in which a metal insert is used between the rail heads for properly spacing the webs and feet of the rails. Most features of this invention can be employed in the use of molds in which the molten aluminothermic steel fiows into the fusion collar-defining space from one side only of the rails and the following claims are intended to cover this embodiment. Other modifications of my invention which fall within the scope of the following claims will be immediately evident to those skilled in this art.

What I claim is:

1. In the pressure-fusion welding of rails by the alumino-thermic method, the process which comprises abutting the ends of two rails to be welded in such fashion that a gap is left between the bases and webs of said rails to receive molten alumino-thermic metal, constructing a mold around the resulting joint provided with a fusion collar-defining space surrounding the webs and bases of said rails and including passageways extending substantially horizontally along the under part of the rail heads on either side of the joint and on either side of the rail heads; said passageways terminating in constricted channels spaced slightly from said joint and extending upwardly following the contour of the rail heads; preheating said joint by passing heated gases upwardly through said collar-defining space, through said horizontal passageways, upwardly through said constricted channels and then horizontally over the tops of the rail heads, then pouring an alumino-thermic charge into said mold in such manner that said collar-defining space and said horizontal passageways are filled with molten alumino-thermic metal; said metal being passed upwardly through said constricted channels to substantially fill the same; flowing alumina-thermic slag over the tops of the rail heads, and then forcing the rail heads together to produce pressure welding of said heads.

2. In the process of welding rails by the alumino-thermic method the preheating step which comprises passing heated gases through mold cavities around the feet and webs of two abutting rails at the joint therebetween, then substantially horizontally beneath the rail heads for a short distance to either side of the joint, then upwardly and at increased velocities in contact with the rail heads through relatively constricted passageways spaced on either side of the joint and then horizontally across the tops of the rail heads, whereby the heating is distributed substantially uniformly throughout the transverse cross-section of the rail.

3. In the pressure-fusion welding of rails by the alumino-therrnic method, the process which comprises forming a fusion collar around the feet and webs of two abutting rails at the joint therebetween, said fusion collar also extending beneath the rail heads from the joint to a short distance on either side and upwardly around the faces of the rail heads in strips spaced slightly from the joint, said fusion collar having a width around the feet of the rails which is substantially equal to the. width. of the collar beneath the rail heads, these wideportions being; connected. by a relatively: narrow portion extending along the webs of the rails and pressure welding the rail heads while formingsaid fusion collar.

4. In the process of welding rails by the alumino-thermic method,.the steps which comprise abutting two rails in such fashion that the heads are flush while the webs and the bases are spaced slightly, constructing a mold around the joint, passing molten steel into the space between said webs and bases, said steel being confined by mold cavities extending around said webs and bases, passing the molten steel through mold passageways extending beneath the heads of the rails on both sides of the rails for a short distance to either side of the joint and then upwardly through constricted mold channels conforming to the shape of the rail heads, the dimensions of said passageways and said constricted channelsbeing such that the steel is substantially congealed before it reaches the tops of said channels, whereby the height reached by the molten steel in said channels is controlled.

5. In the process of welding rails by the alumino-thermic method, the steps which comprise forming a base fusion collar from molten steel around the bases of abutting rails at the joint and a head fusion collar extending beneath the rail heads from the joint to a short distance on either side while excluding said molten steel from between the rail heads, the width of the head and base fusion collars being substantially equal, and.

also forming a web fusion collar surrounding the webs of said rails at the joint having a width substantially less than the width of said base and said fusion collars.

6. In the pressure-fusion welding of rails by the alumino-thermic method, the steps which comprise forming a mold around the joint between two abutting rails; said mold having a fusion-collar defining space surrounding the bases and the webs of 'the rails and extending upwardly around the faces of the rail heads; filling said space with molten steel from an alumino-thermic charge while excluding slag from said space and protecting the faces of said rails from contact with said slag, then pouring said slag on top of the rail heads at points spaced on both sides of the joint in such manner that the slag flows along the tops of the rail heads from said points towards said joint.

'7. In the welding of rails by the aluminothermic process, the steps which comprise abutting two rails together in such fashion that the webs and bases are spaced slightly, forming a mold around the resulting joint provided with a web fusion collar-defining space around the webs of said rails having a width substantially equal to the width of the gap between said webs, and having two cross pouring gates connecting with said web collar-defining space from opposite sides of the rails and at points below the heads of said rails, the width of said cross pouring gates being substantially equal to that of the gap between said webs, and pouring molten metal of an alumino-thermic charge through said cross pouring gates and into said collar-defining space in such manner that the alumino-thermic slag is excluded from said space.

8. A mold for welding abutting rails by the alumino-thermic method which comprises capacity chambers for receiving an alumino-thermic charge positioned on either side of the abuttin rails at the joint, said chambers being separated from the rails by mold projections and terminating downwardly in cross pouring gates at a point below the heads of the; rails, a fusion collardefining space surrounding the webs and bases of said rails-and'connected: with said crosspouring gates, said collar. defining space extending beneath the rail heads from the'joint to a short distance on either side and terminating upwardly in constricted channels spaced slightly on either side of the joint and conforming to the shape of the rail heads.

9. A mold for welding abutting rails by the alumino-thermic method adapted to surround and enclose the ends of the rails, which comprises web and base fusion collar-defining spaces surrounding the webs and the bases of said rails, a head fusion collar-defining space extending beneath the heads of said rails from the joint to a short distance on either side and terminating upwardly in constricted channels spaced a short distance from the joint on either side.

10. The mold of claim 9 wherein said base fusion collar-defining space and said head fusion collar-defining space are of about equal width while the width of said web fusion collar-defining space is substantially less.

11. A mold for welding abutting rails by the alumino-thermic method comprising mold parts adapted to surround and enclose the ends of the rails and forming with said rails a mold cavity extending through said mold parts adjacent the joint between said rails, and mold projections covering the gauge and offside faces of the rail heads at the joint thereby protecting these parts from contact with the slag of an alumino-thermic charge, said mold projections defining a slag basin extending along the tops of the rails at the joint and adapted to receive said slag.

12. The mold of claim 11 wherein said mold encloses a fusion collar-defining space surrounding the bases and webs of said rails, the width of said fusion collar-defining space around the bases of said rails being substantially equal to the width of said slag basin while the width of said fusion-collar defining space around the websof said rails is substantially less.

13. The mold of claim 11 wherein said mold projections also define deflectional horizontal surfaces adapted to direct the preheating gases across and in contact with the tread surfaces of the rails.

14. In the alumino-thermic method of welding, the process which comprises making a riser-less weld by abutting two metal parts to be welded, forming a mold about the resulting joint with a mold cavity adjacent the parts at said joint and including any space left between said parts, said mold cavity being provided with at least one constricted passageway extending upwardly along a metal section at which fusion welding is not desired, the dimensions of said passageway being sufficiently small to cause the congelation of any molten weld metal rising therein, then introducing molten alumino-thermic metal into the lower portion of said cavity below the said passageway in amount sufficient to fill said lower portion and to force the weld metal upward into said constricted passageway, whereby congelation of the weld metal takes place in said passageway thereby preventing any further rise of weld metal in said mold cavity.

15. A mold for welding abutting rails by the alumino-thermic method comprising mold parts adapted to surround and enclose the ends of the rails and forming with said rails a mold cavity extending through said mold parts adjacent the joint between said rails, and mold projections covering the gauge and offside faces and under surfaces of the rail heads at the joint thereby protecting these parts from contact with the slag of an alumino-thermic charge, said mold projections defining capacity chambers on either side of said rails as well as a slag basin extending along the tops of the rails at the joint, said mold projections also forming slag spillways adapted to conduct the slag of an alumino-thermic charge '5 from said capacity chambers into said slag basin.

EDWARD F. BEGTRUP.

Images