US2060328A

US2060328A - Method of reforming worn rail joint bars

Info

Publication number: US2060328A
Application number: US50340A
Authority: US
Inventors: Langford George
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-11-18
Filing date: 1935-11-18
Publication date: 1936-11-10
Anticipated expiration: 1953-11-10

Description

-Nov. 10, 1936. G. LANGFORD 2,060,328

METHOD OF REFORMING WORN RAIL JOINT BARS Fi'led Nov. 18, 1935 fave/22 07? GEO/ "p6 Zaggfo-rd MWMvM,

Patented Nov. 10, 1936 UNITED STATES PATENT OFFICE METHOD OF REFORMING WORN RAIL JOINT BARS My invention pertains to the reforming or reshaping of rail joint bars used to couple rail ends together to form a continuous track. More particularly it is directed to the reforming of the 'worn rail contacting surfaces of a worn rail joint bar. As the wear of a rail joint is greater at its central portion than at its end portions, trouble is encountered in restoring the worn central portion. The end portions interfere because being less worn, they require less restoration than does the central portion. But there must be careful blending of the central and end restorations, for the reason that a worn surface of a bar must be accurately finished throughout its length. The graduation of restoration from' the more worn central portion to the less worn end portions pre sents difficulties, and it is these that my invention is intended to overcome. My methodof doing this will be fully understood by those skilled in the art, from the following description and accompanying drawing.

In the drawing:

Fig. 1 is an end view of a rail joint bar.

Fig. 2 is an inside view of the bar of Fig. 1 showing the worn condition of its top fishing or rail bearing surface after use in a joint. I

Fig. 3 is a fragmentary inside view of the top of a bar showing how the worn top fishing surface may be restored.

Fig. 4 is a graphic illustration of the ordinary difficulty encountered in reforming a worn bar.

Fig. 5 shows a method of reforming used in the prior art.

Figs. 6 and 7 illustrate a variation of means employed in the method of my invention.

Fig. 1 is an end view of a bar with top member or head I.

Fig. 2 is an inside view of the bar of Fig. 1 showinghow the bar is usually worn after it has been in service in a joint, fishing surface ab in Fig. 1 being worn down to a'-b' in Fig. 2. This wear is greatest at the central portion 0 of the bar, decreasing through the intermediate portions I, there being in most cases little wear at the end portions E. The top fishing surface is worn'so that it is longitudinally concave at c, this concavity extending into I in amount more or less depending upon the stiffness of the bar. If the bar is to .be repaired for use again, its top fishing surface worn to a'--b' must be restored by being pushed up to at least its original or normal position ab.

Metal has been worn off the top fishing surface so that in Fig. 1, the inner portion at least of the head of the bar 8 dtc eased in depth,- For example, depth 11-0 in Fig. 1 has been decreased at the central portion 0 of the bar so that it is less than at the ends E. The bar head having. become thinned centrally in this manner, it then becomes necessary to compensate for central loss of metal', either by providing more metal centrally or by pushing it up to its place again as shown in Fig. 3 which is an inside view of the bar head of Fig. 2 after the bar is reformed.

In Fig. 3, the worn top fishing surface a'-b is pushed up to its normal position w-b from the opposing under surface c-d. Broadly described, surface a-b become by wear longitudinally c'on-' cave, is made straight again by concaving surface c-d. In the prior art, this is disclosed in 15 my Patent No. 1,808,467, issued June 2, 1931',

which teaches" movements of metal in a bar by use of longitudinal convexities in a die. In Fig. 3, surface c-d-is concaved-centrally by a-corresponding die wall longitudinally convexed so as to produce a longitudinal concavity on the bar. For a better understanding of the following description, the word straight used in connection with a bar or die; with a surface of a bar or die;

with a die wall; or with a support under a die; will mean longitudinally straight without any longitudinal convexity. or' concavity. In my invention I use as a preferred means, two dies, 2. top and a bottom one, both straight. The die walls, corresponding to surfaces of the bar, are made straight from end to end, each one being machined in by straight cutting from end to end in an ordinary planing or milling machine. A pair of straight dies when closed, defines a die cavity whose cross-section will correspond closely to the cross-section of the bar. The main feature of straight dies is that, when closed empty neither the die cavity as a whole, nor any one of the three individual cavities corresponding, to the 1 three members of a bar, are reduced in transverse or cross-sectional area at center. The cavityas a whole, and its component cavities are uniform' throughout their lengths and not reduced centrally, as would be the case if one or. more die walls were convexed longitudinally.

- It is more diflicult to plane or machine die grooves with convexities than it is to make straight grooves without convexities. However in the use of dies with straight grooves, there is the difliculty of central wear in the bar to contend with. Fig. 4

is a side view graphically illustrating the ordinary difliculty of reforming a bar head in straight dies. 4

l representsthe bar head between

dies

2 and 3. Under pressure P, die 2 is shown closed upon the bar I.

In Fig. 4, the worn fishing surface of a bar is represented by the concave line a-a'-a which is to be restored to its normal position -11-41. The opposing surface d-dd being unworn must be pushed up to dd--d so that the surface a-a'-a may also be pushed up. But inasmuch as the pressure P has encountered dead resistance at the unworn ends of the bar before any of the pressure reaches the center, this end resistance must be overcome before any pressure can reach the central portion of the bar, made thinner by wear than at the end portions. The pressure P in Fig. 4 depends entirely upon the resistance of the ends of the bar to the closing of the dies. In a power press, the top die moves up and down with a fixed amount of stroke and the greatest pressure occurs when the dies are finally closed upon the bar. If there is no bar in the dies, there will be no pressure when the dies are closed. It is the resistance of the bar to movement of its metal in the dies that creates pressure P in the moving die 2, and reactions R in the fixed die 3. It is well known in the art what great damage may result when occasionally. two bars may be accidentally placed one on top of the other in the dies. Either the press is stalled and unable to complete its stroke, or else its main shaft, tierods or some other large part is broken and the press wrecked. In such a case, a 1,000 ton press may be strained far beyond its capacity by the great excess of pressure or dead resistance.

The bar cannot be merely squashed out at its ends so that pressure may reach the center. Such end resistance is enormous and would soon incapacitate the means for applying pressure. Die 2 will close upon the bar until the pressure P is distributed at the ends as shown by the arrows, but to close further upon the bar and distribute pressure inward and on the central portion of the bar is impossible unless there be some way of removing or relieving the enormous end resistance, represented by pressure reactions R. Pressure does not necessarily result in material redistribution of metal as has been described and shown in Fig. 4, where pressure on the ends of the bar does not result in a redistribution of metal there. The bar fills the dies at the ends and resists enormously the closing of the dies, as it has no place to go. Longitudinal movement is not appreciable. The pressure is vertical, and the movement of metal transverse. The important thing is to secure transverse movement of metal at the worn center portion of the bar. This cannot be accomplished as long as the end portions of the bar resist the closing of the dies. End resistance or pressure must be overcome before pressure can reach the center so as to make the metal flowthere and fill the dies.

Fig. shows how this may be done by using a die-wall convexity v as previously referred to and disclosed in my Patent No. 1,808,467, issued June 2, 1931. Surface cc'--e-represents the longitudinal convexity of a die-wall used to forcemetal to restore a fishing surface to at least its normal position aa-a.' Before pressure P is applied the top surface of the bar is concaved longitudinally andits bottom surface is straight. Howeverthe die wall or surface which impinges upon the bottom surface of thebar is not straight as c--c-c on the bar, but is bulged up or convexed to cc'-,c. As the top die'2 descends upon the bar I, the first contact is at the top ends a, but the first forming pressure is at bottom center as the convex surface c-c'c of die 3 strikes the straight surface c-c'-c of the bar. T e fi st 11 of material metal is upward at the center. The vertical amount of convexity in die surface c-c'-c is greater than the vertical amount of concavity in the worn bar surface, the latter being represented in Fig. 4 by a-a'--a. Die convexity c-c'c reduces the central portion of the closed die cavity, and the excess of die convexity over bar concavity insures that the closed die cavity will be too small at center rather than too large as compared with the cavity at the ends. The metal of the bar will then fill the dies at center before it fills the dies at the ends, thereby avoiding dead resistance at the ends as shown in Fig. 4. As the dies close further, movement of metal exten'ds decreasingly toward the ends, and the pressure upon the bar, continually increasing at center extends decreasingly to the ends. When the dies are finally closed, the die cavity is completely filled with flowed metal at its central portion, dead resistance occurring there before it reaches the ends. Fig. 5 shows the dies finally closed and the top surface H of the bar reformed. It is the distribution of pressure when the dies are closed that we are mainly concerned with. At such time, the distribution of pressure would be opposed by a similar distribution of reactions, and pressure P distributed as per the small arrows on the top surface of the bar pointing downward, would be opposed by a similar distribution of arrows on the bottom surface of the bar pointing upward. These increments of the pressure represent increments of resistance to further flow of metal. It is not the preliminary shaping when the metal will bend or flow freely, but the final resistance when the metal will not fiow freely, that determines how the final and greatest pressure should be distributed. The method of Fig. 5 has the effect of concentration of pressure P at center as per the small arrows. End resistance to this pressure is relieved or removed. As die 2 closes upon bar I, the effect upon the bar is graduation of pressure from the center outward, diminishing toward the ends. End resistance is removed, and there is nothing to prevent the die 2 from completing its stroke, and when the stroke is completed, pressure P is concentrated at center, diminishing. toward the ends. The effect of this is a wave of vertical pressure in each direction from the center toward the ends as per the horizontal arrows 4.

Fig. 6, illustrating my invention, is drawn similarly to Figs. 4 and 5. By thinning die 3 sufficiently, it will actually bend under pressure P when die 2 is fully closed, from its normal dotted line position to the full line position shown. The top die 2 of Fig. 6 is similar in all respects to the top die 2 in Figs. 4 and 5. However the bottom die 3 is thinned vertically; that is all of its vertical dimensions in amounts so that the die will not bend under a given pressure, are reduced to amounts which will permit the die to bend under said given pressure.

Die 3 is made of tool steel and normally rests fiat upon a die holder or other suitable support S having its top surface longitudinally straight without any vertical convexity, as indicated by the line :vy-z in Fig. 6. Support S is of suitable type to permit of lengthwise bending of die 3. For this purpose it may be resilient, or may be of relatively soft material, or of any other character suitable for the purpose. The position of die 3 when first placed upon support S is indicated by the dotted line a:z and the line :cyz in part dotted, the latter coinciding with the upper surface of support S, initially straight and fiat. Under the final pressure die 3 is bent or bowed lengthwise, with its center raised and ends depressed, the support S, at its upper surface being correspondingly bent or shaped, as shown in full lines in Fig. 6. Ordinarily it would seem impossible to bend appreciably a tool steel die thus supported, but under the great reforming pressure commonly used and with a reduced vertical die thickness related to the pressure, die 3 will bend under the pressure as shown. When the pressure is released, the die will spring back to its original position, as will the support S, if the latter be resilient.

Preferably, the supporting means S for die 3 is relatively soft. The practice is to position die 3 upon its supporting means and to then use several trial bars to establish the final vertical setting. The setting is as in Fig. 4. The pressure upon the bar is at the end portions only, and the vertically thinned bottom die 3 in Fig. 6 actually bends so that its top surface assumes the longitudinal convexity c-c'-c conforming to the worn longitudinal concavity in either the top or bottom surface of the bar. In the first few trial bars, most of the pressure is expended at the ends in crushing and spreading the top surface of the supporting means S at the ends so that said supporting means is no longer longitudinally straight and becomes convexed as shown by the full lines a:"yz". It might be thought that the top surface of the supporting means S should be so convexed originally, but I find that crushing and forcing it to the desired shape is the simplest and most accurate way, as the top surface'of the die support becomes shaped to meet actual conditions and determines the right amount of bending of the die under the pressure. Only a few trial bars are needed to crush the top surface of the supporting means at its end portions under a given pressure, but the die must be thin enough vertically to bend as shown under said given pressure; and inversely, given a vertical thickness of die, the pressure must be sufilcient so that the die will bend. End resistance R is relieved by this bending of the die 3, permitting travel of pressure upon the bar from the center to the ends, so that pressure can reach the center of the bar when the die supporting means S has been longitudinally convexed on its top surface. Die wall ccc then has a convexity ccc as in Fig. 5 when the dies are closed upon the bar. Die 3 bends down at the ends under pressure P but when the dies are separated, die 3 springs back up at the ends and becomes straight again without the longitudinal convexity cc'-c being made preferably of tool steel or alloy steel. In this way, the straight die of Fig. 6 made straight originally with die wall planed from end to end without convexities as previously described may be made to take the shape of the convex-walled die of Fig. 5, so that the convexity of the die wall will conform to the worn concavity in the bar, thereby reducing the cross-sectional area of the die cavity at center to the reduced cross-sectional area of the worn bar at center when the dies are closed upon the bar. From the small arrows in Fig. 6, it may be seen that the pressure upon the bar first concentrated at the ends travels inward as the die 3 bends. The latter may bend down at the ends or up at the center. In either case, the initial pressure is confined to the ends of the bar and cannot extend into the center until the die bends so that the originally straight die surface ccc will be convexed to ccc. Pressure will then extend to the central portion of the bar and cause fiow of metal there until the central portion of the die cavity is filled. When the die is finally filled at center, the resistance there causes the pressure at center to rise rapidly, but this can not take place until after the application of pressure at the ends and after die 3 bends down at the ends or up at the center as described. This is exactly opposite to the effect produced in Fig. 5, wherein the first application of pressure begins at the center and then extends decreasingly outward, the pressure rising rapidly and being greatest at center, decreasing to the ends as the dies are finally closed upon the bar.

Fig. '7 shows another application of my method. Instead of thinning a die, pressure P may be in- .creased to the point where one of the dies will bend or where both dies will bend as shown. These dies made originally straight-walled, as previously described become bent and convexwalled under the pressure and will become straight again when the pressure is removed. In this way I secure the benefits of a convex-walled die from a. straight-walled die. This is accomplished by so relating the vertical thickness of the die to the pressure, or by relating the pressure to the vertical thickness of the die that the die will bend as described, under pressure when the dies are fully closed upon the bar. I may wish-to convex a die -wall of one die and not the other, and this is done by thinning one die and not the other. This enables me to avoid any convexity on a selected surface of the bar itself.

My method may then be briefly described as one intended to restore a worn or recessed surface of a bar. The preferred means employed is a pa r of dies which when closed include a cavity conformingto a bar. In this cavity are one or more die walls made straight longitudinally, said die wall becoming convexed when the dies are closed upon the bar. this convexity resulting from a bending down of the die wall under pressure so 'that the die cavity is reduced at center relative to that at the ends. A die may be thinned vertically to accomplish this bending, or the pressure may be increased so that its vertical thickness will not prevent its bending and longitudinally convexing, by concentrated pressure, the supporting surface beneath. In either case the die wall must bend from straightness to convexity, tudinally.

By means of end resistanc I bend the die vertically under pressure so that its working face comprising one or more die walls is longitudinally convex, permitting the reforming pressure to travel inwardly to thecenter. I may not secure such a concentration of pressure at the center. as can be attained in the method of Fig. 5, nevertheless the pressure attainedin my method of Fig. 6 may be made enough to properly reform the worn central portion of the bar after the end portions are reformed. Only moderate pressure is required to make heated metal fill a die cavity, but when the cavity becomes filled, the metal is enormously resistant to further forming pressure. The metal being confined in the cavity has no place to go, and further effort to make it go anywhere will result only in enormous and destructive resistance. It is this sort of resistance that is encountered at the end portions of a worn bar reformed in longitudinally straight dies. I do notremove this resistance but I overcome it so that forming pressure may be transmitted inward to the worn central portion of the bar.

longi- Explained simply, my method is one which employs longitudinally straight dies, which when closed empty, define a cavity uniform in all of its horizontal and vertical transverse dimensions from end to end. When closed upon a bar, the vertical thickness of one or both dies are so related to a given pressure that said die or dies actually bend as described. When bent, the die cavity becomes smaller at the center than at the ends, thus adjusting itself to the shape of the bar which because of central wear is smaller, that is, of less cross-sectional. area at center than at the ends. Dies made originally straight, bend momentarily under the pressure, thereby shaping the die cavity momentarily to the shape of the worn bar. Within certain ranges a die will bend a little more on a more worn bar than on a less worn bar, and the method thus accommodates itself to variations of wear.

In its broad aspect my invention is a method of reforming bars whereby the pressure first reforms the end portions of a bar and then continues to the center of the bar to reform the center portion. The preferred shaping means is a pair of dies with longitudinally straight walls. In respect to the means used, I do not wish to be too strictly limited as long as I keep within the scope of the method claimed, whereby the first application of pressure is at the ends and then continuing to the center. It is possible to use dies wherein there may be a projection or irregularity in a die wall interrupting its straight continuity and yet which does not cause a first application of pressure at the center. I, therefore, may use any means other than the preferred means as long as I restrict myself to reforming pressure, first at the end portions of the bar and then at the center portion.

What I claim is:

1. The method of restoring the fishing surfaces of a worn rail joint bar, which comprises heating the bar to a working temperature and subjecting it to forming pressure, said forming pressure being first concentrated at the end portions of the bar and progressing in relatively decreasing amount to the center, and finally increasing at center so as to efiect a maximum spread of metal at the central portion of the bar.

2. The method of reforming a worn rail joint bar, which comprises heating the bar to a working temperature and then subjecting it to a forming pressure, said forming pressure, being first concentrated at the end portions of the bar to reform said end portions and progressing toward the center of the bar to reform intermediate portions of the bar, and finally increasing at the center portion of the bar to reform said center portion.

3. The method of restoring the fishing surfaces of a worn rail joint bar, which comprises heating the bar to a working temperature, subjecting it to forming pressure between opposed dies having bar receiving cavities normally straight lengthwise of the dies, and bending one of the dies lengthwise by pressure applied first to the end portions of the bar thereby subjecting the center portion and the end portions of the bar to forming pressure by the die surfaces in the closing of the dies and accurately forming the fishing surfaces at said portions of the bar.

4. The method of reforming the centrally worn fishing surface of' a rail joint bar, which comprises heating the bar to a working temperature and subjecting it to forming pressure, said forming pressure being first applied at the end portions of the bar and then extendingto the center so as to effect a maximum displacement of metal at center to restore said centrally worn fishing surface.

5. The method of reforming a worn rail joint bar, which comprises heating the bar to a working temperature and subjecting it to forming pressure, said forming pressure being first applied at the end portions of the bar and then at the center portion so as to effect a maximum displacement of metal at center to restore one at least of the top and bottom fishing surfaces at the center portion of the bar.

6. The method of reforming a worn rail joint bar, which comprises heating the bar to a working temperature and subjecting it to forming pressure, said forming pressure being first applied to the end portions of the bar to reform one at least of the top and bottom fishing surfaces at the end portions, and then being applied to the center portion to reform one at least of the top and bottom fishing surfaces at the center portion.

GEORGE LANGFORD.