Abstract:
A pallet car for conveying material to be processed is disclosed. The pallet car includes first and second sidewalls formed from sidewall members that each include a metal frame and a heat-resistant liner, such as formed from refractory. The refractory formed on the metal frame of the sidewall members provides insulation for the metal frame without the need for a hearth layer of pre-processed material in the material bed of the pallet car. The sidewall member including the refractory layer increases the effective volume of the pallet car, which increases the overall efficiency of the furnace and material processing procedure.

Description:
BACKGROUND 
       [0001]    The present disclosure generally relates to a pallet car for conveying material to be processed through a furnace. More specifically, the present disclosure relates to sidewall members for creating first and second sidewalls of a pallet car that each include a heat-resistant lining to eliminate the need for a hearth layer along the sidewalls. 
         [0002]    Straight grate pallet cars are used to transport mineral material, such as iron ore pellets, through a furnace for sintering and oxidizing. The mineral material being processed is carried through the furnace on a series of aligned pallet cars. Each car has a mineral bed that contains the material being processed.  FIG. 1  illustrates a pallet car  10  that represents the current state of the art. The pallet car  10  includes a pallet frame  12  that defines a generally horizontal support surface  14 . The frame  12  includes a pair of end castings  16  that each support a series of rollers  18  that support the weight of the pallet car  10  during movement of the pallet car through the furnace. 
         [0003]    The pallet car  10  includes a first sidewall  20  and a second sidewall  22  that extend along the entire length of the pallet car  10  to support a bed of mineral material  24  to be processed. In the prior art pallet car  10  shown in  FIG. 1 , both the first and second sidewalls  20 ,  22  are formed from a lower casting  26  and an upper casting  28 . The upper and lower castings are both formed from metallic material and combine to form the first and second sidewalls  20 ,  22 . 
         [0004]    Since each of the sidewalls are formed from metal castings, the prior art pallet car  10  utilizes a hearth layer  30  of pre-processed material. The hearth layer  30  extends upward along both the first sidewall  20  and the second sidewall  22  as well as along the top surface of the grate bars  32  supported along the support surface  14  of the frame  12 . The hearth layer  30  serves as a heat sink to protect the pallet car sidewall castings  26 ,  28  from the high temperatures required in the furnace for processing the mineral material  24  into usable product. In the embodiment shown in  FIG. 1 , the material that needs to be processed is shown by the green pellets  34  which are separated from the sidewall castings  26 ,  28  and the grate bars  32  by the hearth layer  30 . As can be understood in  FIG. 1 , the total volume of material  24  that needs to be processed in the area shown by  34  is reduced due to the pre-processed material that forms the hearth layer  30 . After the material  34  is processed, both the material  34  and the hearth layer  30  are removed from the pallet car  10  and a new hearth layer  30  is created. Thus, the use of the hearth layer  30  reduces the operating efficiency of the furnace due to the re-processing of the material that is required to form the hearth layer  30 . 
       SUMMARY 
       [0005]    The present disclosure generally relates to a pallet car that is used to convey mineral material, such as iron ore, through a furnace for processing within the furnace. 
         [0006]    The pallet car includes a base that defines a horizontal support surface for receiving the mineral material to be processed. The base includes a plurality of rollers that allows the pallet car to move through the furnace during processing of the mineral material. A plurality of grate bars is supported on the support surface of the base to insulate the base while the base is within the furnace. 
         [0007]    The pallet car includes both first and second sidewalls that are formed on opposite sides of the base. The first and second sidewalls, in combination with the grate bars, define a product bed for receiving the mineral material being processed. In accordance with the present disclosure, each of the first and second sidewalls is formed from a plurality of sidewall members that are aligned in an end-to-end relationship to define the first and second sidewalls. The plurality of sidewall members each include a metal frame and a heat-resistant liner that is attached to an inner surface of the metal frame. Since the plurality of sidewall members defines the first and second sidewalls, each of the sidewall members is in contact with the mineral material during processing within the furnace. The heat-resistant liner formed on the inner surface of the metal frame provides heat insulation for the metal frame, thereby eliminating the need for a hearth layer along the sidewalls as was required in prior art systems. 
         [0008]    In one embodiment of the disclosure, the heat-resistant liner is formed from a refractory material that is molded onto the metal frame. The molding process for attaching the heat-resistant liner onto the metal frame allows the sidewall member to be formed and later installed as a single piece. In one embodiment of the disclosure, the inner surface of the metal frame includes a plurality of anchors that act to hold the refractory along the inner surface of the metal frame. The plurality of anchors can have various different shapes and configurations and are positioned on the metal frame prior to molding the refractory material onto the metal frame. 
         [0009]    In one embodiment of the disclosure, a retainer is positioned between each of the sidewall members and the plurality of grate bars. The retainer is connected to the sidewall member and provides lateral support for the grate bars. The retainer includes a metallic backing frame and a heat-resistant liner. The heat-resistant liner is exposed to the material during processing and provides thermal insulation for the metallic backing frame. In one embodiment of the disclosure, the heat-resistant liner is formed from the same refractory material as used on each of the sidewall members. 
         [0010]    In accordance with the present disclosure, individual sidewall members can be created and installed on pre-existing pallet cars. In such an embodiment, the sidewall members would replace prior art sidewall members and allow pre-existing pallet cars to be reconfigured and used without the need for the hearth layer along the sidewalls. In such an embodiment, the sidewall members would each include a metal frame and a heat-resistant liner attached to the inner surface of the metal frame. 
         [0011]    Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The drawings illustrate the best mode presently contemplated of carrying out the disclosure. In the drawings: 
           [0013]      FIG. 1  is an end view of a prior art pallet car; 
           [0014]      FIG. 2  is an end view of a pallet car utilizing the sidewall members of the present disclosure; 
           [0015]      FIG. 3  is a magnified end view showing one of the sidewall members mounted to the pallet car; 
           [0016]      FIG. 4  is a perspective view illustrating one of the sidewall members; 
           [0017]      FIG. 5  is a section view of the sidewall member and retainer; 
           [0018]      FIG. 6  is a front view of one of the sidewall members; and 
           [0019]      FIG. 7  is a back view of one of the sidewall members. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]      FIG. 1  illustrates a pallet car  40  constructed in accordance with the present disclosure. Much like the prior art pallet car  10  shown in  FIG. 1 , the pallet car  40  is used to transport mineral material, such as iron ore pellets, through a furnace for sintering and oxidizing. The pallet car  40  includes a base  42  that includes a central casting  44  that defines an upper support surface  46 . In the embodiment shown in  FIG. 2 , the upper support surface  46  is generally horizontal and provides support for a series of individual grate bars  32 . The grate bars  32  are each formed from a heat-resistant material and provide thermal protection for the top surface  46  of the central casting  44 . Each of the individual grate bars  32  can be more clearly seen in the section view of  FIG. 3 . 
         [0021]    As illustrated in  FIGS. 2 and 3 , the central casting  44  includes a pair of spaced end walls  48  that are each connected to one of the end casting  50 . The end casting  50  is connected to the end wall  48  by a series of bolts  52 . The bolts  52  each include a head  54  and a nut  56  to removably connect the end casting  50  to the central casting  44 . As illustrated in  FIG. 2 , each of the end castings  50  supports a series of rollers  18  that allow the individual pallet car  40  to roll through a furnace in a known manner. 
         [0022]    As illustrated in  FIG. 2 , the pallet car  40  includes a first sidewall  58  and a second sidewall  60  located on opposite sides of the central casting  44 . Each of the two sidewalls  58 ,  60  extends vertically above the series of grate bars  32  and defines a product bed  62 . The product bed  62  receives a supply of material  34  to be processed by the furnace. As can be understood in the comparison of  FIGS. 1 and 2 , the hearth layer  30  is present only along the top of the grate bars  32 . Thus, the volume of material  34  that can be received within the material bed  62  in the embodiment of  FIG. 2  is larger than the volume of material in the prior art pallet car  10  shown in  FIG. 1 . This increase in volume is due to the elimination of the hearth layer  30  along the sidewalls as required by the prior art embodiment of  FIG. 1 . The elimination of the hearth layer  30  along the sidewalls is possible due to the configuration of the first and second sidewalls  58 ,  60 , as will be described in greater detail below. 
         [0023]    Referring now to  FIG. 3 , each of the end castings  50  includes a generally horizontal support plate  64  that extends from the vertical end wall  66 . The vertical end wall  66  is used to attach the end casting  50  to the end wall  48  of the central casting through the series of bolts  52 . The support plate  64  provides for a point of connection for each of the sidewall members  68  that combine to form both the first sidewall  58  and the second sidewall  60 .  FIG. 4  is a perspective view of one of the sidewall members  68 . It should be understood that a plurality of the individual sidewall members  68  are positioned in an end-to-end relationship to define both the first sidewall  58  and the second sidewall  60 . 
         [0024]    As shown in  FIGS. 3 and 5 , the individual sidewall members  68  each include a metal frame  70  and a heat-resistant liner  72  securely attached to and supported by the metal frame  70 . As can be seen in  FIGS. 4 and 5 , the metal frame  70  includes a lower, mounting portion  74  and a support wall  76 . Support wall  76  is a generally plate-like member that includes an inner surface  78  and an outer surface  80  that are separated by the thickness of the support wall  76 . As can be understood in  FIGS. 4 and 7 , the support wall  76  extends between a pair of spaced side flanges  82  that define the overall length of the sidewall member  68 . Each of the side flanges  82  extends inwardly from the support wall  76 . Each of the side flanges  82  also define the ends of the mounting portion  74  of the sidewall member  68 . As best shown in  FIG. 4 , the mounting portion includes a front face surface  84  that includes a pair of spaced mounting holes  86 . As illustrated in  FIG. 5 , each of the mounting holes  86  extends through the front wall  88  from the front face surface  84  and into a receiving cavity  90 . As can be seen in the back view of  FIG. 7 , each of the mounting holes  86  is contained within the cavity  90 , which is in turn defined by a pair of vertical support webs  92 . 
         [0025]    As can further be seen in  FIG. 7 , the back surface  80  of the support wall  76  includes a horizontal web  94  and a vertical web  96  that provide additional strength and stability for the support wall  76 . 
         [0026]    Referring now to  FIG. 3 , in one embodiment of the disclosure, the support wall  76  includes a plurality of anchors  98  attached to the front surface  78  of the support wall  76 . Each of the anchors  98  extends away from the inner surface  78  and provides a point of attachment for the heat-resistant liner  72 . In the preferred embodiment of the disclosure shown in the drawing figures, the heat-resistant liner  72  is formed from a refractory material that is molded onto the metal frame  70 . The anchors  98  provide a durable method of attaching the molded refractory material to the metal frame  70  such that the refractory material does not separate from the metal frame  70  during use. Alternatively, it is contemplated that the heat-resistant liner  72  could be attached to the metal frame  70  utilizing other connection methods, such as bolts or some other type of attachment mechanism. In such an embodiment, the heat-resistant liner  72  would be a separate component that can be physically connected to the metal frame  70 . 
         [0027]    As can be understood in  FIG. 3 , each of the sidewall members  68  is securely attached to the support plate  64  of the end casting  50  by a plurality of bolts  100 . Each bolt  100  extends through a bottom wall  102  of the metal frame  70  and through an aligned opening formed in the support plate  64  of the end casting  50 . One or more nuts  104  are used to removably secure each of the individual sidewall members  68  in the manner illustrated. The mounting holes used to receive the bolt  100  are shown by reference numeral  106  in  FIG. 7 . Although this type of mounting arrangement is shown in the drawing figures to secure each individual sidewall member  68  to the frame of the pallet car, other forms of attachment are contemplated as being within the scope of the present disclosure. 
         [0028]    Referring now to  FIGS. 3 and 5 , a retainer  108  is used to lock the grate bars  32  in place between the first and second sidewalls. The retainer  108  includes a metal backing frame  110  and a heat-resistant liner  112 . In the embodiment shown in  FIG. 4 , the backing frame  110  includes a back wall  114 , a bottom wall  116  and a front lip  118 . The combination of the back wall  114 , bottom wall  116  and front lip  118  define a receiving cavity that holds the heat-resistant material that forms the liner  112 . In the embodiment shown, the heat-resistant material that forms the liner  112  is also a refractory material. The refractory material provides heat-resistant insulation for the metal material that forms the backing frame  110 . 
         [0029]    The refractory material that forms the heat-resistant liner  112  surrounds a series of spaced nuts  120  that are lined with access openings  122 . The openings  122  are generally aligned with the mounting holes  86  such that a bolt can extend through the mounting holes  86  and openings  122  and be received within the internally threaded nut  120 . In this manner, the retainer  108  can be securely attached to the front face surface  84  and securely positioned between the sidewall member  68  and the individual grate bars  32 , as best shown in  FIG. 3 . 
         [0030]    Although the embodiment shown in the drawing figures includes a specific attachment method for each of the sidewall members to the frame of the pallet car, different mounting arrangements are contemplated as being within the scope of the present disclosure. Additionally, the retainer  108  shown in the drawing figures could be eliminated in alternate embodiments. However, in accordance with the present disclosure, each of the sidewall members is created utilizing a metal frame and a heat-resistant liner, such as a liner formed from refractory. The heat-resistant liner formed integrally with the metal frame provides heat resistant insulation which can eliminate the need for a hearth layer. Although a hearth layer could also be utilized with the sidewalls constructed in accordance with the present disclosure, it is believed that such a hearth layer would not be required while operating within the scope of the present disclosure. 
         [0031]    As discussed above, the heat-resistant liner protects both the metal support frame  70  of the sidewall member  68  and the metal backing frame  110  of the retainer  108 . The use of the heat resistant liner allows the sidewalls of the pallet car to provide the required thermal insulation for the metal frames and eliminates the need for the hearth layer as in the prior art embodiment of  FIG. 1 . 
         [0032]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.