Abstract:
A rapid discharge railcar door comprised of a main body composed of a polymer reinforced by an aluminum frame, the railcar door being designed to provide sufficient strength against load-bearing forces and withstand changes in temperature. The main body of the door is made from a polymer using a thermoplastic or thermoset molding process, such as injection molding, casting, resin transfer molding, reaction injection molding (RIM), and reinforced reaction injection molding (RRIM). The door reduces the overall weight of the railway car, thereby allowing more coal to be shipped per car.

Description:
[0001]    This application claims priority from U.S. Provisional Application 60/136,183, filed May 27,1999, which application is incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates in general to a new and improved rapid discharge, corrosion resistant, railcar door for railway coal cars, and more particularly to a rapid discharge coal car door made of a thermoplastic or thermoset polymer formed in a molding process, such as injection molding, casting, resin transfer molding (RTM), reaction injection molding (RIM), and reinforced reaction injection molding (RRIM), over an aluminum frame that significantly lowers the weight of the door to allow for more coal to be loaded in the railway car, and which provides sufficient strength and resistance to changes in temperature.  
         BACKGROUND OF THE INVENTION  
         [0003]    Coal continues to be a prevalent source of energy, particularly for electric generating stations. Millions of tons of coal are transported by railway cars each year within the United States between a coalmine and a user facility. In order to maintain the condition of the railways and to insure safety, regulations are imposed to limit the total weight of each railway car. Currently, the total weight allowed for each railway car, including the weight of the car itself, is 286,000 pounds. As the coal companies obviously desire to ship the most amount of coal per railway car or ship a certain amount of coal with the least amount of railway cars, there has been a continuous effort to lower the weight of the railway cars while still maintaining the railway cars&#39; structural integrity. However, one limiting factor in improving railway cars is the fact that as the coal is transported across the country, it may pass through various states and be subjected to various weather conditions. For example, when coal passes through sub-zero temperatures, it will freeze, and thus require the coal to be subjected to a thawing process. Thus, any components in the coal cars must be able to withstand the various stresses imparted upon them.  
           [0004]    Heretofore, it has been known to use an aluminum door with a steel frame for rapid discharge coal car doors. The use of an all metal door, especially with a steel frame, results in a door having a weight of almost 190 pounds. Heretofore used all-steel doors are even heavier. Most coal cars are hopper cars with multiple outlets in the bottom selectively opened and closed by discharge doors. A commonly found hopper car has sixteen discharge doors working together in pairs to cover eight discharge outlets. The total weight of sixteen all-metal doors is over 3000 pounds, or about one percent of the total allotted weight per railway car.  
           [0005]    Others have considered using certain plastics, such as polyurethane, as a hopper door material. However, such polymeric doors generally would not withstand the heating the doors must be subjected to during the thawing process. Further, it is unclear whether doors made of regular polyurethane would have sufficient strength to adequately support the coal load and perform adequately as a rapid discharge coal car door.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention is in a polymeric door molded on an aluminum frame that overcomes the weight and temperature change problems of metal and other plastic doors. The door of the present invention is made from a polymer formed in a thermoplastic or thermoset molding process, such as injection molding, casting, resin transfer molding, reaction injection molding (RIM), and reinforced reaction injection molding (RRIM). Certain polymers which are formed using a RIM process provide a light-weight, tough, and strong product that can withstand various stresses and impacts associated with coal loads and the changes in temperature and weather. It should also be appreciated that the door of the present invention may be used on any bottom dumping car carrying granular material, such as plastic pellets and the like.  
           [0007]    Heretofore used aluminum panel steel framed hopper doors weighed about 190 pounds, as above mentioned, while the doors of an embodiment of the present invention molded of a polymer over an aluminum frame weigh about 95 pounds. As there are sixteen doors per the hopper coal car above referred to, the doors of an embodiment of the present invention, which weigh about half as much as the aluminum panel steel framed hopper doors, will reduce the weight of the car by over 1500 pounds. Trains carrying coal often have over 100 coal cars per train. Thus, the use of the doors of the present invention will allow over 150,000 additional pounds of coal per trip for a train with 100 cars. Additionally, the weight reduction involved in the use of such a light door benefits the transporter when the “emptied” coal car is returned to its point of origin for refilling with coal.  
           [0008]    In order to prevent any occurrence of hanging coal, a liner can be placed over the side of the door engaging the coal to provide for a low coefficient of friction and wear resistance surface. One satisfactory material for use in the liner is a black UV resistant ultra-high molecular weight polyethylene (UHMWE).  
           [0009]    It is therefore a primary object of the present invention to provide a rapid discharge coal car door that will be lighter than an aluminum and steel door, thereby reducing the overall weight of a hopper coal car and allowing more coal to be transported per car and per a train of coal cars.  
           [0010]    Another object of the invention is to provide a rapid discharge door for bottom dumping railcars carrying granular materials that will be lighter than an aluminum and steel door, thereby reducing the overall weight of the railcar and allowing more granular material to be transported.  
           [0011]    Another object of the present invention is to provide a rapid discharge coal car door that provides adequate strength against load-bearing forces and which can withstand changes in the weather and the thawing process needed to thaw frozen coal.  
           [0012]    A further object of the present invention is to provide a rapid discharge coal car door having a longer life than heretofore known doors and that will eliminate hanging coal heretofore encountered on steel and aluminum doors, thus allowing the coal car to fully discharge the coal.  
           [0013]    A further object of the present invention is to provide a thinner railcar door by the use of thinner aluminum structure supported by a shrunken polymeric over molding.  
           [0014]    Other objects, features and advantages of the invention will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheets of drawings, wherein like reference numerals refer to like parts.  
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0015]    The invention will be better understood by reference to the appended description and figures in which:  
         [0016]    FIGS.  1  to  5  illustrate the use of coal car discharge doors in a hopper coal car according to the prior art, wherein FIG. 1 is an elevational view of a hopper coal car on an overhead unloading trestle unloading the contents of the car;  
         [0017]    [0017]FIG. 2 is an elevational and somewhat longitudinal sectional view taken through the coal car of FIG. 1 to further illustrate the mechanism for opening and closing the discharge doors;  
         [0018]    [0018]FIG. 3 is a detailed schematic view of a part of the opening and closing mechanism for the discharge doors;  
         [0019]    [0019]FIG. 4 is a bottom plan view taken substantially along line  4 - 4  of FIG. 2 showing the doors associated with the operating mechanism;  
         [0020]    [0020]FIG. 5 is a top plan view of the hopper car of FIG. 2 taken substantially along line  5 - 5  of FIG. 2;  
         [0021]    [0021]FIG. 6 is a perspective view of a discharge door according to an embodiment of the invention looking at the top side of the door;  
         [0022]    [0022]FIG. 7 is a view as that in FIG. 6 except that the door is provided with a liner according to the invention;  
         [0023]    [0023]FIG. 8 is a bottom plan view of the door of FIG. 6;  
         [0024]    [0024]FIG. 9 is a plan view of the aluminum frame that is employed in the door of an embodiment of the invention and around which the polymer making up the body of the door is molded in the RIM process;  
         [0025]    [0025]FIG. 10 is a perspective view of an embodiment of the invention in which a pair of doors that are used side by side and interconnected together by the cross beam and looking at the underside of the doors and showing in exploded form the brackets for interconnecting the beams of adjacent doors;  
         [0026]    [0026]FIG. 11 is a plan view of the doors in FIG. 10 and connected together by the bracket; and  
         [0027]    [0027]FIG. 12 is a view as in FIG. 11 but a modification wherein a single beam is employed for interconnecting a set of doors. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0028]    The railcar discharge door of the present invention is employed for opening and closing discharge openings of a hopper coal car to unload the contents. It will be appreciated that the discharge door of the invention may be used on any kind of hopper railcar having bottom discharge openings for transporting any type of granular material. More particularly, the discharge door of the invention will replace heretofore known all metal discharge doors in order to reduce the weight of the car so that the car&#39;s load capacity can be increased and also to provide a discharge door that may have a longer life than an all metal door. More particularly, the door of the invention is made of a thermoplastic or thermoset polymer molded over an aluminum frame by a molding process, such as injection molding, casting, resin transfer molding, reaction injection molding (RIM), and reinforced reaction injection molding (RRIM), wherein the frame includes hinge members for hinging one edge of the door to the car and beam members for facilitating the inner connection of a pair of doors and connecting to an opening and closing device. Moreover, the door of the invention includes a liner of UV-resistant and abrasion-resistant plastic such as UHMWPE, which also provides a low coefficient of friction surface to assure discharge of the coal or other granular material.  
         [0029]    It will be appreciated that the body of the door may be made of any suitable polymer such as a Telene polymer made by B.F. Goodrich. Telene is a trademark of B.F. Goodrich. A Telene polymer is an impact, temperature (heat and cold), and corrosion resistant polycyclic olefinic thermoset based on dicyclopentadiene monomer. Alternately other polymeric materials are available. For example, the door could be composed of a fiber-reinforced polymer, glass filled or other fiber filled polymers, or other impact and temperature resistant materials. The liner for the door may be made of any suitable UV- and abrasion-resistant plastic that also defines a non-sticking surface for the coal or other contents of the hopper car.  
         [0030]    When polydicyclopentadiene polymerizes around aluminum, the shrunken polymer places the aluminum structure under compressive loads. This compressive load reinforces aluminum joints and members, preventing buckling, warping, distortion, or the like. This new phenomenon allows a design with thinner aluminum sections to be employed in the substructure thereby reducing the weight of the rail car hopper door.  
         [0031]    One form of door according to the invention is disclosed in this application and is principally for use on a hopper coal car of the well-known type shown in FIGS.  1  to  5 . As above mentioned, heretofore known doors are all metal and were made from a steel frame having an aluminum or steel pan secured to the frame.  
         [0032]    The coal car discharge door of the present invention would be mountable on a hopper coal car, as shown in FIGS.  1  to  5 , wherein the coal car is generally designated by the numeral  16  and includes end slope sheets or walls  17 , upstanding side walls  18  and  19 , and upstanding end walls  20  and  21  defining an open top compartment or hopper  22  (FIG. 2) for loading therein coal or any other suitable granular material. The car  10  includes a plurality of longitudinally spaced apart chutes  23  terminating in transversely spaced apart discharge openings  24  (FIG. 5). Each discharge opening is selectively opened for discharge of coal and thereafter closed by a pair of coacting doors  25  that are hinged to the bottom of the car at one end and opened and closed in clamshell fashion. A pair of transversely spaced apart doors  25  are interconnected together by a spine or beam  27  so that they move together during the opening and closing function. Each door  25  is hinged at its upper end by a suitable hinge  28  to the body of the car.  
         [0033]    Any suitable mechanism may be used to open and close the doors and the mechanism illustrated is pneumatically driven and includes a double-acting pneumatic cylinder  31  mounted at one end of the car which when activated to open or close the doors drives a primary crank arm  32  pivotally mounted on the frame of the car which in turn is pivotally connected to a longitudinally extending drive rod  33  that extends substantially the entire length of the car and which in turn drives a plurality of secondary crank arms  35  pivotally mounted adjacent each set of doors. Each of the secondary crank arms  35  is in turn pivotally connected to one end of an actuating lever  36 , the other end of which is pivotally connected to the spine or beam  27  of a set of side-by-side hung discharge doors. When the doors are in closed position, the linkage and crank arms go to an overcenter position so that the doors cannot open except by operation of the pneumatic cylinder  31 .  
         [0034]    A suitable solenoid operated pneumatic valve  38  is connected between the brake pipe of the car and the pneumatic cylinder  31 . At each side and end of the car a hot shoe  40  is provided for engagement with a contact member mounted adjacent to the track where unloading is to occur for receiving a signal to actuate the solenoid operated pneumatic valve  38  for driving the pneumatic cylinder for opening and closing the doors.  
         [0035]    The discharge door of the present invention is shown in FIGS.  6  to  12  and generally designated by the numeral  45 . This door includes an aluminum frame  47  and a polymer body  48  molded over the frame by the RIM process. It will be appreciated that the size and shape of the door may vary depending upon the discharge opening for which it is designed, although it would generally include the features described below and always include a main body molded over an aluminum frame provided that the design and materials of construction form a structurally sound configuration.  
         [0036]    The aluminum frame  47  not only provides a frame on which the polymer body is molded but also includes hinge elements and a beam or spine enabling the interconnection of a pair of doors where the invention is used to produce a set of doors, such as shown in FIGS.  10  to  12 . The frame  47  in the embodiment shown in FIGS.  6  to  9  includes a pair of parallel spaced apart channel-shaped members  51  and  52 , a crossbar  53  of channel shape extending between the upper ends of the vertically extending members  51  and  52 , hinge members  54  and  55  at the upper ends of the vertical members  51  and  52 , and a spine or beam  56  connected to the lower ends of the vertical members  51  and  52 . While the vertical members  51  and  52  and the crossbar  53  are shown to be of a U-shaped channel configuration, it will be appreciated that they could take the form of T-shaped members or any other suitable shape. Similarly, while the beam  56  is box-shaped, it should be appreciated that it could likewise be of any other suitable cross-sectional shape. Further, the hinge members  54  and  55  include an offset head  54   a  and  55   a  with a transversely extending bore  54   b  and  55   b  for receiving a suitable shaft mounted on the coal car and which thereby makes the doors pivotally mounted to the bottom wall of the coal car or suitable means.  
         [0037]    It will be appreciated that during the molding of the main body of the door under the frame the hinge members  54  and  55  will not be covered with the polymer and likewise an extension  60  of the beam  56  will riot be covered by the polymer so that interconnection with an extension an adjacent door can be facilitated as will be further described below.  
         [0038]    The top side of the main body  45  of the door forms a planar surface  62  (FIG. 6) and a lip  63  is provided around three sides of the body for purposes of coacting with the discharge opening of the car to receive the edges of the discharge opening chute and prevent coal leakage. While the doors for the car illustrated are used in side-by-side or tandem fashion, each door will also coact with an opposing, door, as shown in FIG. 1, for closing the discharge opening. Door  45  accordingly does not include a lip along the edge that will coact with an opposing door to close the discharge opening.  
         [0039]    As seen in FIG. 7, a replaceable liner  65  is suitably secured over the planar surface  62  and within the lip  63 . In this embodiment, this liner is about one-eighth inch thick and is preferably made from UHMWPE of three-and-one-half to six million molecular weight to provide a low coefficient of friction surface against which the coal will bear during transit and freely slide over during discharge. As above noted, this material is abrasion-resistant and preferably black and UV-resistant since it will be subjected to the sun when the car is empty.  
         [0040]    The underside of the door, as seen particularly in FIGS. 8 and 10, includes a plurality of interconnecting transversely extending and longitudinally extending reinforcing ribs  68  as well as angularity extending reinforcing ribs  69  and an outer perimeter reinforcing rib  70  which generally follows the outer contour of the main body. As is apparent, the reinforcing ribs not only interconnect between the vertically extending channel members of the frame but also the horizontally extending crossbar and the beam. This rib design, as well as other suitable patterns, enables the door to withstand the loading of the coal as well as the expansion and contraction endured during temperature changes.  
         [0041]    Where the doors are used in tandem or side-by-side relation, a left-hand and a right-hand door are connected together in a suitable fashion. One manner of interconnecting the doors is shown in FIGS. 10 and 11, wherein the beam extensions  60  of adjacent doors are brought together in abutting and aligned relation, after which angle or L-shaped brackets  72  and  73  are placed upon the extensions at diagonally opposite comers and welded Mito place, as shown in FIG. 11. The angle bracket  72  includes an apertured lug  74  for pivotal connection to an actuating lever  36  of the operating mechanism.  
         [0042]    Another form of connecting two adjacent doors together is illustrated in FIG. 12. These doors, designated  45 A, are made slightly different in that the beam or spine does not include an extension wherein the opposite ends of the beam are substantially flush with the opposite sides of the polymer of the body door. While the beam in this embodiment is preferably box-shaped, it could be of any other suitable cross-sectional shape. Two adjacent doors in this embodiment would not then have to be made as left- and right-hand doors inasmuch as they would then be identical. The doors are interconnected by using a box-shaped connecting beam or spine  76  sized to be telescopically received within the beams of each of the adjacent doors  45 A. The connecting beam  76  is suitably connected to the beams of the doors by welding. huck-bolting or other means which then thereby interconnects the doors as a pair or set. Thereafter, an apertured lug  77  is suitably mounted on the connecting beam  76  such as by welding or otherwise and which serves to be connected to the actuating lever of the operating mechanism. It will be appreciated that the connecting beam and lug may be formed as a one-piece unit. Alternatively, a frame having two sets of vertical and horizontal bars could be secured to a single elongated beam, where the polymer body for each set could be molded at the same time, or one body could be molded at a time. Thereafter, a lug could be secured to the beam at a location between the doors.  
         [0043]    As above mentioned, while the doors illustrated are designed for the hopper coal cars of the prior art shown in FIGS.  1  to  5 , they could be designed for hopper coat cars where the discharge opening or chute would merely require a single door and which could be latched in closed position and suitably unlatched to gravitationally open for discharge of the coal. Moreover, the aluminum frame and molded over polymer door of the present invention could be used on coal cars having longitudinally extending doors wherein it will be appreciated that the frame would have additional vertical bars between the crossbar near the hinges and the beam.  
         [0044]    It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention, but it is understood that this application is to be limited only by the scope of the appended claims.