Abstract:
A tie plate is formed with a profile defining two parallel protrusions with bores for receiving the respective ends of two clips. The two clips engage the flange of a rail to secure the rail to the plate, and therefore, to tie disposed below the plate. Since the protrusions are made integrally with the the plate, the resulting tie plate is able to support the rail securely even in the presence of large forces and/or twisting moments on the rail resulting from a train passing over the plate.

Description:
FIELD OF INVENTION 
     This application pertains to railroad rail fastener systems, and more particularly to a method of manufacturing a tie plate used for mounting railroad tracks on ties or other support means. The tie plate is formed with integral retainers for engaging the resilient clips used for holding the rails in place. 
     BACKGROUND OF THE INVENTION 
     Railroads constitute a major transportation means for moving goods as well as people. However, in order for railroads to operate safely, reliably and inexpensively, it is important to keep their basic infrastructure sound to ensure that the rails are available for service without any down time and are accident free. 
     Inherently, rails and the fastening systems used to keep the rails in place play a crucial part of the railroad infrastructure and designing such fastening systems requires a lot of interdisciplinary effort between engineers, material science experts and heavy industrial manufacturers because the fastening system must be able to hold the rails in place, with very little tolerance in the position for movement and spacing of the rails as high speed passenger trains, or long and heavy freight trains pass over them. 
     It has been found that fastening systems consisting of a tie plate resting on a tie or other support and somewhat resilient clips securing each rail to tie plate are advantageous because they can be made reliably with the clips being able to hold on to the rails and resist tremendous linear and rotational forces on the rails. Of course, the retainers used to hold the clips on the plate are subject to the some of the same forces as the clips and must be able to transmit these forces to the tie plate. Until the present invention, these clips were made separately and were then attached to the tie plates by welding, press-fitting or other similar mechanical means. As a result, it was possible for these retainers to separate from the tie plate, in essence making the clips useless. 
     SUMMARY OF THE INVENTION 
     In one embodiment, the present invention is directed to a method of making plates by forming a metallic piece that has a generally rectangular shape with bottom and top surface; working the metallic piece to form a shaped piece that has a generally flat body with a first end and a second end and a first protrusion and a second protrusion that extends from the first end and the second end, respectively, with the first and second ends disposed in parallel to each other, and the first and second protrusions disposed on the top surface and in parallel top each other; and drilling respective first and second bores from the first and second ends, respectively, through the body. The first and second bores extend only partially along a length of the respective protrusion and the first and second bores are spaced and configured to receive the end of a retaining clip securing a rail to said tie plate. 
     As a result, a tie plate for securing a rail on a tie using first and second clips that have respective clip end, is obtained including a relatively flat body that has a first end, a second end, a top surface and a first and a second protrusion that are formed integrally with the body and extend in parallel on the top surface. The first protrusion extends from the first end and second protrusion extends from the second end. The first and second protrusions are parallel to each other with the first protrusion formed with a first bore sized and shaped to receive one of the clip ends and the second protrusion formed with a second bore sized and shaped to receive the other of the clip ends. The protrusions and the clips cooperate to restrain the rail on said top surface. 
     Holes are also provided in the plate for mounting the plate on a tie. Advantageously, a transversal hole is provided outwardly from each bore. This hole can be used to remove debris from the respective bore to ensure that the respective clip end is seated properly within the bore. 
     The protrusions may extend from one end of the plate to the other, or may extend only partially from one end toward the opposite end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an orthogonal view of a rail supported by a conventional tie plate and clip; 
         FIGS. 2A and 2B  show plan and side views respectively of another conventional plate; 
         FIG. 3A  shows an orthogonal view of a tie plate constructed in accordance with this invention; 
         FIG. 3B  shows a plan view of the tie plate of  FIG. 3A ; 
         FIG. 3C  shows a cross-sectional view of the plate of  FIGS. 3A-3B  taken along lines X-X; 
         FIG. 3D  shows an elevational side view of the tie plate of  FIG. 3A-3C  taken along direction H in  FIG. 3C ; 
         FIG. 3E  is a somewhat enlarged end view of the plate of  FIGS. 3A-3D  showing an end of a clip being housed in a bore of the plate; 
         FIG. 4  shows a flow chart for manufacturing the tie plate of  FIGS. 3A-3D ; 
         FIG. 5A  shows an orthogonal view of the plate of  FIGS. 3A-3D  supporting a rail; and 
         FIG. 5B  shows a front view of the tie plate of  FIG. 5A  and the rail mounted thereon. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a standard rail track  10  with a rail  12  resting on conventional ties  14 . Rail  12  includes a foot  20 , web  22  and a head  24  and is supported on the ties  14  by a support assembly  26 . 
     Typically, the support assembly  26  includes a tie plate  30  resting directly or indirectly on a tie  14  and secured by several spikes  32  or other conventional means. In the configuration shown in  FIG. 1 , the assembly  26  further includes a clip retainer or bushing  34  receiving an end of a clip  36 . The bushing  34  is welded or otherwise affixed to the tie plate  30 . The clip  36  has another end that is contact with an upper surface of rail foot  20 . The clip applies a force on the rail  12  to insure that the rail  12  stays on top of the tie and plate  30  and does not move sideways or travel too much up and down. 
     The support assembly  26  has several disadvantages. It requires the bushings  34  to be mounted at the factory, thereby adding to the costs of the assembly. The bushings  34  add significant weight to the assembly. In use, the bushings  34  may separate and fall off the plate  30  resulting in a potentially dangerous condition. 
       FIGS. 2A and 2B  show a conventional plate  50  with a different configuration. While plate  30  is generally flat, plate  50  is formed with two parallel humps  52 ,  54  extending in parallel with the lateral edges  56 ,  58 . Each hump  52 ,  54  forms a somewhat semicylindrical cavity  60 ,  62 . These cavities  60 ,  62  being sized and shaped to receive the respective ends  64 ,  66  of clips similar to clips  36  in  FIG. 1  and used to retain the rail  12  on the tie plate  50  as described above. Holes  70  are used to secure the tie plate  50  to one of the ties  14  by spikes or other conventional means. 
     Plate  50  is cheaper to make then the plate  30 . In addition, since the plate itself holds the ends of the clips, no additional clip retaining means such as bushings are required. Therefore, plate  50  is lighter and takes less time to assemble. However, it has been found that during the process of shaping the plate in the configuration shown, the portions of the plate forming the humps  52 ,  54  can become thinner than the rest of the plate. The humps are subject to tremendous forces as a heavy train goes over the plate, and after a time these humps  52 ,  54  can fracture. Moreover, because the cavities  60 ,  62  have typically a transversal shape that is larger than the cross-sectional diameters of the clips, the ends of clips  64 ,  66  are free to travel up and down with each wheel passing over the plate, causing excessive wear and tear of the plate and the clip ends. 
       FIGS. 3A-3E  show a new tie plate. This plate  80  is still generally flat but is formed with two protrusions  82 ,  84 . Each protrusion  82 ,  84  has a top surface  82 A,  84 A that is relatively cylindrical, except for two substantially vertical sections  86 A,  86 B facing each other and extending in parallel. 
     Each protrusion is formed with a horizontal bore  88 ,  90  sized and shaped to receive an end  100  of a retainer clip, as discussed in more details below. Preferably, the length of each bore  88 ,  90  only needs to be same or a little longer then the length of clip end  100 . Preferably, the depth of each bore  88 ,  90  is equal to or less than half the overall dimension L ( FIG. 3B ). 
     Preferably, a small hole  94  is provided at the end of each bore  88 ,  90 . One purpose of the hole  94  is to allow personnel in the field during installation to clean out any foreign matter and debris from the respective bore  88 ,  90  thereby insuring that the clip ends  100  can be inserted into the bores easily. The hole  94  may also be used to secure the plate  80  to ensure that the plate is not stolen. The plate  80  further includes two lateral wings  96 ,  98  extending laterally outwardly from the bores  82 ,  84 . These wings  96 ,  98  are formed with conventional apertures  99  for securing the tie plate  80  to conventional ties as described below. 
     The tie plate  80  is advantageous over the prior art plate of  FIGS. 2A, 2B  because its bores  88 ,  90  have much thicker sidewalls than the top walls of the cavities  60 ,  62 . As a result the plate is stronger and is able to withstand large forces without being damaged. Another advantage of the plate  80  is that because the bores  88 ,  90 , are closed, no foreign matter or debris can get into these bores after installation. 
     The process for making a plurality of plates  80  is now described in conjunction with the flow chart of  FIG. 4 . In step  110  a flat sheet  200  of an appropriate metal alloy is formed using standard manufacturing techniques. In step  112  the sheet  200  is cut into several metal strips  202 , each strip  202  having a width approximately equal to the desired length L of plate  80 . (Dimension L is measured in a direction parallel to the rail  12 ). 
     In step  114  each strip  202  undergoes a shaping process (for example, rolling) to form a shaped strip  204  having a predetermined cross sectional profile, such as the one shown in  FIG. 3C . 
     In step  116 , the shaped strip  204  is partitioned transversally along, lines  206  into several individual plates  208  using shearing or other conventional techniques. As can be seen in  FIG. 4 , the plates  208  do not have any bores or holes yet. 
     In step  118  bore  88  is made from one end of each plate. 
     In step  120  a second bore  90  is drilled from the other end of the plate. 
     In step  122  the apertures  99  are formed in the plate  208 . Of course steps  118 ,  120 ,  122  can be interchanged, or performed simultaneously. 
     The end result is a plurality of plates  80  illustrated in  FIGS. 3A-3D   
     Because a significant portion of each protrusion  88 ,  90  does not include a bore, and because the bore has a diameter just large enough to receive the clip ends, the protrusions and the plate are much stronger and can withstand large distorting forces much better. 
     In an alternate embodiment, the protrusions  88 ,  90  extend only partially across the plate. Of course, in this case, each protrusion starts from a respective edge of the plate. 
       FIG. 5A-5B  show the plate  80  supporting a rail  300 . As can be seen in these figures, the rail  300  fits preferably snugly between walls  86 A,  86 B of plate  80 . Standard spikes (not shown) can be used to attach plate  80  to a conventional tie. Clips  302  are used to attach and secure the rail  300  to the plate. Each clip  302  has a respective end  304  that is straight and extends into one of the bores  88 ,  90 . As discussed above, prior to the present invention, separate shoulders had to be provided that were attached to a plate and were used to engage the ends  304  of clips  302 . As a result of the present invention, separate shoulders are no longer necessary. 
     Numerous modifications may be made to this invention without departing from its scope as defined in the appended claims.