Patent Application
20130074566
The present invention relates to a process of recycling worn railroad rails.
There are known processes for recycling worn railroad rails which involve heating the rail within a furnace to a plastic state for molding thereof by means of rolling operations. Often, such rolling operations are associated with separate processing of cut portions of the rail, such as its head, web and base. In some instances, all portions of the worn rail are processed along one shaping line into bar products, such as fence posts or rebars.
The recycling of worn rails without cutting thereof has been proposed, as disclosed for example in U.S. Pat. Nos. 328,937, 852,983, 1,086,789 and 1,206,606. Such prior known methods of recycling worn rails have never proved successful in producing a one-piece billet or slab, because of problems created by the formation of laps, seams and folds during the rolling operations, giving rise to quality defects in the product produced. It is also known from U.S. Pat. No. 4,982,591 to heat a worn, one-piece rail to a plastic state which is initially deformed by a multi-stage rolling action to a slab constituted by flattened base and head extensions of an undeformed web portion of the rail. The slab is then edged in stages to effect thicknening of its intermediate portion and formation of a billet without any lapping, seaming or folding.
Further, it is known from U.S. Pat. Nos. 7,073,238 and 7,996,973 to heat the rail and slit it into two pieces in a first reduction pass and then subsequently pass the two pieces through a single mill pass line such that each piece of the rail is deformed to have a generally uniform shape. In the event that the rail has a through hole in a web portion of the rail, the slit preferably occurs through the area of the hole.
A problem encountered with the processing of rails, particularly where the rails are slit into separate pieces, is that the size and configuration of the head portion of the rails may vary greatly from rail to rail due to different wearing history of the bearing surface of the rail. Depending on when the rail was replaced, traffic conditions during rail usage, weather and orientation of the rail, the size and shape of the head portion may vary greatly from its initial size and shape. When the rail is slit into pieces before it is reshaped to any degree, the variations in the head size will be maintained as variations in the size of the pieces, making it difficult to process the rail pieces in a single line pass operation and to achieve substantially identical final end piece sizes.
A solution to this problem would be an improvement in the art.
In an embodiment, the present invention provides a method of recycling a one-piece rail having a base portion and a head portion spaced from each other along an axis by a substantially flat web portion. The method includes a step of heating the material of the rail to a plastic state. Another step includes feeding the heated rail through a first reduction pass to form a bar having a former head portion, a web portion and an former base portion in which a starting cross section of the rail is reduced in at least one dimension without slitting the rail. For this reason, the method of the present invention is referred to as “no-slit” since it leaves the first reduction pass without being slit. Another step includes feeding the bar through a second reduction pass in which the cross section of the bar is further modified.
The method proceeds with the step of slitting the bar along the web portion into two bar pieces, one piece containing the head portion and one piece containing the base portion, as the bar leaves the second reduction pass. Another step includes rolling the two pieces of the bar, in a single pass line, through a series of reduction passes to produce a desired final cross section of the bar pieces.
In an embodiment, the rail is heated to a temperature of at least 1900° F. prior to being fed into the first reduction pass.
In an embodiment, the rail initially has a width in a direction from the base portion to the head portion, a height of the head portion perpendicular to the width and a height of the base portion perpendicular to the width being greater than a height of the web portion, and in the first reduction pass the rail is deformed into the bar so as to make the head portion smaller and the base portion smaller than their initial heights.
In an embodiment, in the first reduction pass, as the rail is deformed into the bar, the width of the rail increases.
In an embodiment, in the first reduction pass, as the rail is deformed into the bar, the height of the web portion remains substantially unchanged.
In an embodiment, in the second reduction pass, the bar is maintained at a temperature sufficient to cause the material of the bar to remain in a plastic state.
In an embodiment, in the second reduction pass the bar is further deformed so as to make the former head portion smaller and the former base portion smaller than their heights following the first reduction pass.
In an embodiment, in the second reduction pass, the heights of the former head portion, the former base portion and the web portion are made substantially identical.
In an embodiment, at the exit of the second reduction pass, the bar is slit into two substantially identical bar pieces.
In an embodiment, in the third reduction pass, the bar is maintained at a temperature sufficient to cause the material of the bar to remain in a plastic state.
In an embodiment, at the third reduction pass, the two bar pieces pass through identical shaped rollers to produce substantially identical shaped pieces.
The features of the present invention which are believed to be novel, are set forth with particularity in the appended claims. The invention, together with further objects and advantages, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in the several Figures in which like reference numerals identify like elements, and in which:
In step 32, the heated rail 20 is fed through a first reduction pass (a first pair of opposed rollers used to change the cross sectional shape of the rail) in a direction of an elongated length of the rail in which a cross sectional shape of the former rail is modified without slitting the rail and which results in a bar 20A (
Typically initially the base portion 22 has a dimension 33, referred to in this rotated orientation as a height, greater than a corresponding dimension 36, also referred to as a height, of the head portion 24. Both of these heights 33, 36 are initially greater than a height 38 of the web portion 28. Throughout this document the term “height” is meant to mean the dimension that is parallel to a smallest dimension of the web portion 28 of the rail, regardless of the orientation of the rail 20 as it is presented to the first reduction pass. The height dimension extends perpendicular to an elongated length L of the rail 20 (
The actual size and shape of the head portion 24 may vary from rail to rail due to differences in the wearing of the bearing surface of the rail and the point at which the rail was removed for recycling. In is in particular this variation of head portion size from rail to rail that renders the present invention more favorable than earlier processes in that the rail is first modified in shape and cross section in the first reduction pass and the second reduction pass before being split so that variations between the two split pieces are minimized. Following the first reduction pass, the cross sectional shape of the former rail is changed sufficiently such that it no longer is considered to be a rail, but instead is now referred to as a bar 20A.
In an embodiment, in the first reduction pass of step 32, the rail 20 is deformed into the bar 20A so as to make a height 36A of a former head portion 24A smaller and a height 33A of a former base portion 22A smaller than their initial heights. In some embodiments, as the heights 33, 36 are decreased in the first reduction pass, the width 40 of the bar 20A from the base portion 22 to the head portion 24 is increased. This increase is referred to as the spread of the material of the rail. Also, in some embodiments, in the first reduction pass of step 32, as the rail 20 is deformed, the height 38 of the web portion 28 remains substantially unchanged.
Another step 34 includes feeding the bar 20A through a second reduction pass in which the cross section of the bar is further modified as shown at 20B in
The method proceeds to step 42 with the slitting of the bar 20B along the web portion 28B into two pieces (20B′ and 20B″ in
The method proceeds to step 44 which includes rolling the two pieces 20B′ and 20B″ of the bar 20B, in a single pass line, through a series of reduction passes to produce (step 46) a desired final cross section of the pieces (20C as shown in
As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art.
