Patent Publication Number: US-2003221811-A1

Title: Railcar sideframe casting method

Description:
BACKGROUND OF THE INVENTION  
       [0001] Railcar sideframes are cast from steel. Sideframes are cast in a mold. The mold has a top or cope section and a bottom or drag section. The cope and drag sections of the mold are each contained in a flask. A pattern is placed over one end of each flask and sand is rammed over the pattern. The pattern is then removed leaving an impression of the casting&#39;s external surfaces in the cope and drag section mold sand.  
       [0002] Sideframe castings typically have hollow sections that reduce the sideframe&#39;s weight while maintaining strength. The sideframes&#39; hollow sections are formed with cores. Cores define the hollow sections&#39; internal surfaces, and may define some external surfaces of the casting.  
       [0003] Cores are typically made from sand. The sand contains a binding agent to maintain the core&#39;s integrity while handling the core during the casting process. Typical binders include phenolic resin, polyurethane, and sodium silicate. A popular core sand binder is Ashland Inc.&#39;s Isocure® binder.  
       [0004] Cores are made in core boxes. The core box includes a drag section and a cope section. Cores can be produced manually or with automated core making equipment such as a core blower. To make a core with a core blower, the core box cope and drag sections are fastened together, and the core box placed on the core blower. Tooling is required to fit the particular core box to the core blower. This tooling typically includes a blow plate, a gassing manifold (or plate), a stool, and various core ejection systems. Different tooling is generally necessary to fit each different core box to the core blower.  
       [0005] The core blower produces cores by blowing sand into the core box. The core blower typically uses sand containing binders such as Isocure® that cure the core in the core box. The core blower injects curing gas into the core box to cure the core. The cope and drag sections of the core box are separated leaving the core.  
       [0006] Once made, the cores are placed in the bottom or drag mold. Cores are supported and located in the drag mold in a number of ways. Cores may be supported and located in the mold on core prints which extend from the core surface into cavities in the mold. Core prints are the usually the best way to support and locate cores in the mold. Where core prints are not possible, cores may also be supported on chaplets. Chaplets, however, are expensive and can cause stress risers in the casting. Cores may also be supported and located by other cores. When supporting and locating one core by another core, there is no reference to the mold surface for the supported core. This can result in loss of casting wall thickness dimensional control.  
       [0007] After the cores are placed in the drag mold, the cope mold is placed on top of the drag, and the cope and drag are fastened together. Molten metal is poured into the mold and allowed to cool, thus hardening the metal. The casting is then removed from the mold and the sand is shaken out. The casting is then typically heat treated, machined, and finished.  
       [0008] There are numerous freight railcar manufacturers. Each freight car customer typically requires a different sideframe casting design. Each sideframe casting design requires patterns, molds, cores, and core arrangements specific to that design. Thus, each sideframe casting design requires different mold cope and drag patterns to form the external surfaces of the casting, and different shaped cores to make the internal surfaces of the casting. Each different core shape requires a separate core box. Separate tooling to fit each core box to the core blower is also necessary.  
       [0009] Manufacturing different sideframe designs also requires frequent core box and tooling changes to core production lines. This results in significant downtime and increased costs in core and casting production costs. The railcar sideframe casting method of the present invention addresses these and other problems.  
       SUMMARY OF THE INVENTION  
       [0010] The present invention provides a method of casting a sideframe including the steps of dividing the sideframe into design zones, and providing a core module for forming internal surfaces of the sideframe casting in the design zones. The design zones include a right outer leg design zone, a left outer leg design zone, a right tension member design zone, a left tension member design zone, and a bolster opening design zone.  
       [0011] In another aspect, the present invention includes the step of varying at least one core module to correspond with varying sideframe casting geometry in at least one design zone. The core modules include a right outer leg core module, a left outer leg core module, a right tension member core module, a left tension member core module, a right column wall core module, a left column wall core module, and a bolster opening bottom core module. The core modules define internal surfaces of the sideframe casting in their respective design zones.  
       [0012] In a further aspect, the present invention provides the ability to support and locate core modules within a mold through use of core prints. The sideframe has a right and a left pedestal top opening, and the right and left outer leg core modules each have pedestal top core prints extending into the mold sand. The pedestal top core prints define the right pedestal top opening. The pedestal top core prints have a protrusion extending from them that extends into the mold sand.  
       [0013] The sideframe also has right and left pedestal end openings. The right and left outer leg core modules each have a pedestal end core print extending into the mold sand, the pedestal end core print defining the right and left pedestal end openings. The pedestal end core prints have a protrusion from the core prints into the mold sand.  
       [0014] The sideframe has a top wall. The right and left outer leg core modules each include a top wall core print extending from their outer surface through holes in the top wall of the sideframe and into the mold sand.  
       [0015] The right and left tension members have an outer wall, the outer walls have openings. The right and left tension member core modules each include a core print extending from their outer surfaces into the mold sand and forming at least part of the outer wall openings. The core prints have a protrusion extending from the core print into the mold sand. The bolster opening bottom core module includes a core print extending from its outer surface into the mold sand and forming at least part of the outer wall opening.  
       [0016] The right and left side windows of the sideframe each have a top perimeter and a bottom perimeter. The top perimeter has no outside corner radius. The right and left tension member core modules each have a core print extending from their outer surface that spans the entire top perimeter of their side windows.  
       [0017] The right and left outer leg core modules include shelves corresponding with a weight bearing surface of their respective tension member core module. The bolster opening bottom core module includes a shelf corresponding to weight bearing surfaces on the right and left tension member core modules.  
       [0018] In another aspect of the present invention, the sideframe has a central longitudinal plane and a bolster opening. The bolster opening has a right side and a left side and a column wall on the right side and on the left side of the bolster opening. Right and left column wall core modules form the internal surfaces of the right and left column wall of the bolster opening. The right and left column wall cores are adapted to be inserted into a cavity in their respective tension member core module.  
       [0019] Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and the figures. 
     
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
     [0020]FIG. 1 is a perspective view of a railcar sideframe and bolster.  
     [0021]FIG. 2 is a perspective view of a railcar sideframe.  
     [0022]FIG. 3 is a side plan view a railcar sideframe showing the design zones of an embodiment of the present invention.  
     [0023]FIG. 4 is a bottom view of a railcar sideframe.  
     [0024]FIG. 5 is a top perspective view of one end of a railcar sideframe.  
     [0025]FIG. 6 is a bottom perspective view of one end of a railcar sideframe.  
     [0026]FIG. 7 is a top perspective view of one end of a railcar sideframe showing a hole in its top wall in accord with one embodiment of the present invention.  
     [0027]FIG. 8 is a perspective view of core modules of an embodiment of the present invention.  
     [0028]FIG. 9 is a bottom perspective view of an outer leg core module of an embodiment of the present invention.  
     [0029]FIG. 10 is a top perspective view of an outer leg core module of an embodiment of the present invention.  
     [0030]FIG. 11 is one end perspective view of one side of a tension member core module of an embodiment of the present invention.  
     [0031]FIG. 12 is another end perspective view of one side a tension member core module of an embodiment of the present invention.  
     [0032]FIG. 13 is a perspective view of another side of a tension member core module of an embodiment of the present invention.  
     [0033]FIG. 14 is a perspective view of a portion of core modules of an embodiment of the present invention.  
     [0034]FIG. 15 is a bottom perspective view of a bolster opening bottom core of an embodiment of the present invention.  
     [0035]FIG. 16 is a top perspective view of a bolster opening bottom core of an embodiment of the present invention.  
     [0036]FIG. 17 is a section view of a prior art core print.  
     [0037]FIG. 18 is a section view of a core print of an embodiment of the present invention.  
     [0038]FIG. 19 is a perspective view of core modules of an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0039]FIG. 1 shows a typical railcar truck  10 . There are two trucks  10  per railcar. The railcar truck  10  includes two wheelsets  12 , a pair of sideframes  14 , and a bolster  16 . Each sideframe  14  accommodates the bearings  17  of the wheelsets  12 . The sideframes  14  rest on the wheelsets  12 . The bolster  16  extends between the sideframes  14 . The bolster  16  is supported by the sideframes  14  on springs  18 . The springs  18  may be supported directly on the sideframe  14 , or on an intermediate assembly (not shown).  
     [0040]FIG. 2 shows a sideframe  14  made in accord with the method of the present invention. The sideframe  14  has a bolster opening  20  to accommodate the bolster  16  and springs  18 . On either side of the bolster opening  20  are a right column wall  22  and a left column wall  24 . The right and left column walls  22  and  24  have external wall surfaces  26  and  28 .  
     [0041] The sideframe  14  also includes a right side window  30  and a left side window  32 . The right side window  30  and left side window  32  each have a top perimeter  34  and bottom perimeter  35  extending around their entirety. Each side window  30  and  32  has an external surface  36  and  38 .  
     [0042] The sideframe  14  further includes a right tension member  40  and a left tension member  42 . The right and left tension members  40  and  42  have right and left openings  44  and  46  in their outer walls  48  and  50 .  
     [0043] The sideframe  14  also includes a top compression member  52  extending substantially the length of the top  54  of the sideframe  14 . At the left end  56  and right end  58  of the sideframe  14  are left pedestal section  60  and right pedestal section  62 . Each of the pedestal sections  60  and  62  have pedestal jaws  64  and  66 . The pedestal jaws  64  and  66  extend around the bearings  16  of the sideframes  14 . The left and right pedestal sections  60  and  62  also include a left pedestal roof  68  and a right pedestal roof  70 . The left and right pedestal roofs  68  and  70  rest on the bearings  16  of the wheelsets  12 . The left and right pedestal jaws  64  and  66  have in their outer walls left and right pedestal end openings  72  and  74  (FIG. 6). The pedestal end openings  72  and  74  reduce the overall weight of the sideframe  14 .  
     [0044] At the bottom  76  of the bolster opening  20  is a bolster opening bottom section  78 . The bolster opening bottom section  78  may include a spring seat  80 . The springs  18  rest on the spring seat  80  in a sideframe that has a spring seat  80 . The bottom section  78  is beneath the spring seat  80 .  
     [0045] The sideframe  14  also has top openings  82  and  84  in each of the left and right pedestal section sections  60  and  62  (FIG. 5). The top openings  82  and  84  reduce the weight of the sideframe  14 .  
     [0046] The method of the present invention includes dividing the sideframe into design zones  81 . FIG. 3 shows the design zones  81  of a preferred embodiment of the present invention. The design zones  81  include a left outer leg design zone  86 , a left tension member design zone  88 , a bolster opening design zone  90 , a right tension member design zone  92 , and a right outer leg design zone  94 . The design zones  86  through  94  generally correspond to areas of the sideframe  14  where railcar customer-driven design changes are likely to occur.  
     [0047] The left outer leg design zone  86  preferably includes the left pedestal section  60 , which includes the left pedestal jaw  64  and left pedestal roof  68 . Similarly, the right outer leg design zone  94  preferably includes the right pedestal section  62 , which includes the right pedestal jaw  66  and right pedestal roof  70 .  
     [0048] The left tension member design zone  88  preferably includes the left tension member  42 , the left side window  32 , and a portion  96  of the top compression member  52 . Similarly, the right tension member design zone  92  preferably includes the right tension member  40 , the right side window  30 , and a portion  98  of the top compression member  52 .  
     [0049] The bolster opening design zone  90  includes the bottom section  78  beneath the bolster opening  20 . A spring seat  102  may be located at the bottom  100  of the bolster opening  20 . The spring seat  102  supports the bolster  16  on springs  18 . The spring seat  102  has teeth  104  to accommodate the springs  18 . The bolster opening design zone  90  also includes a left column wall  24  and a right column wall  22  on either side of the bolster opening  20 . The top compression member  52  extends across the top  110  of the bolster opening  20 . The left and right columns  24  and  22  preferably have bolt holes  112  to affix a wear plate (not shown) to the sideframe  14 .  
     [0050]FIG. 4 shows a bottom view of the sideframe  14 . The sideframe  14  has a central longitudinal plane  114  which divides the sideframe  14  into a top half  116  and a bottom half  118 . A central transverse plane  120  divides the sideframe  14  into a left half  122  and a right half  124  (FIG. 14). FIG. 5 is a top perspective view of the left half  122  of the sideframe  14 . FIG. 5 shows the left pedestal top opening  82  in the left pedestal section  60  on each side of the central longitudinal plane  114 . FIG. 6 is a bottom perspective view of the left half  122  of the sideframe  14 . FIG. 6 shows the left pedestal end opening  72  in the left pedestal jaw  64 . FIG. 6 also shows the left outer wall opening  46  in the outer wall  50  of the left tension member  42 .  
     [0051] The method of the present invention includes providing a core module for forming internal surfaces of the sideframe  14  corresponding to the design zones  81 . FIG. 8 shows the core modules  123  that correspond to the design zones. The cores modules  123  preferably include a left outer leg core module  124 , a left tension member core module  126 , a bolster opening bottom core module  128 , a right tension member core module  130 , and a right outer leg core module  132 . The core modules  123  also include a left column core module  134  and a right column core module  136 . These core modules  123  define the internal surfaces of hollow sections of the sideframe  14 .  
     [0052] The left outer leg core module  124  corresponding to the left outer leg design zone  86  is shown in FIGS. 9 and 10. FIG. 9 shows a bottom perspective view and FIG. 10 a top perspective view of the left outer leg core module  124 . The right outer leg core module  132  is the mirror image of the left outer leg core module  124 . The right outer leg core module  132  corresponds to the right outer leg design zone  94 . The left outer leg core module  124  has a left pedestal roof portion  138  for forming the internal surfaces of the left pedestal roof  68 , and a left jaw portion  140  for forming internal surfaces of the left pedestal jaw  64  of the sideframe  14 . Preferably, the left pedestal roof portion  138  forms the entire internal surface of the pedestal roof  68 , and the pedestal jaw portion  140  forms the entire internal surface of the pedestal jaw  64  on both sides of the central longitudinal plane  114  of the sideframe  14 .  
     [0053] Extending from the outer surface of the left outer leg core module  124  is a pedestal top opening core print  142 . The pedestal top opening core print  142  forms the pedestal top opening  82 . Also extending from the outer surface of the left outer leg core module  124  is a pedestal end opening core print  144 . The pedestal end opening core print  144  forms the pedestal end opening  72  of the sideframe  14 . The pedestal top opening core print  142  and pedestal end opening core print  144  extend into the mold sand of the drag mold to support and locate the left outer leg core module  124  in the mold.  
     [0054] In a preferred embodiment, the pedestal top opening core print  142  has a protrusion  146  extending from its underside that further serves to locate the core in the drag mold and prevent core movement. The protrusion  146  is preferably located at the outer edge  148  of the pedestal top opening core print  142 , and is preferably triangular in shape. The pedestal end opening core print  144  also preferably has a protrusion  150  on its underside. The protrusion  150  is preferably rectangular and is located at the outer edge  154  of the pedestal end opening core print  144 .  
     [0055] The left outer leg core module  124  also has a shelf  156  located at its inner edge  158 . The shelf  156  mates with the left tension member core module  126  to support the weight of the left outer leg core module  124  as described below. The shelf  156  preferably extends across the entire width of the inner edge  158  of the left outer leg core module  124 .  
     [0056]FIG. 10 shows a top perspective view of the left outer leg core module  124 . FIG. 7 shows a top perspective view of the sideframe  14 . A top wall  160  of the sideframe  14  has an opening  162 . A top wall core print  164  extends from the outer surface of the left outer leg core module  124  through the opening  162  in the top wall  160  of the sideframe  14  (FIG. 10.) The top wall core print  164  with the pedestal top opening core print  142  and end opening core print  144  and protrusions  146  and  150  primarily locate the left outer leg core module  124  in the mold.  
     [0057]FIGS. 11 and 12 show top perspective views of the left tension member core module  126  corresponding to the left tension member design zone  88 . The right tension member core module  130  corresponds to the right tension member design zone  92 , and is the mirror image of the left tension member core module  126 . The left tension member core module  126  preferably has a left side window portion  166  for forming the left side window  32  of the sideframe  14 . The left tension member core module also preferably has a left tension member portion  168  for forming internal surfaces of the left tension member  42 , and a top compression portion  170  for forming internal surfaces of the top compression member  52  of the sideframe  14 . Preferably, the left tension member core module  126  forms the entire internal surfaces of the left tension member  42  and top compression portion  170  on both sides of the central longitudinal plane  114  of the sideframe  14 . The left tension member core module  126  has a cavity  172  to accommodate the left column core module  134  that defines the internal surface of the left column wall  24 .  
     [0058] The left tension member core module  126  has a weight bearing surface  174  at its outer end  176 . The weight bearing surface  174  mates with the shelf  156  of the left outer leg core module  124  to support its weight. Preferably, the weight bearing surface  174  extends across the entire width of the outer end  176  of the left tension member core module  126 . Where the left outer leg core module  124  and left tension member core module  126  meet forms a joint  177 . A similar joint  179  is formed where the right outer leg core module  132  and right tension member core module  130  meet.  
     [0059] The left tension member core module  126  has at its inner end  178  another weight bearing surface  180 . The weight bearing surface  180  mates with the bolster opening bottom core module  128  as described below. Extending from the outer surface of the left tension member portion  168  is a core print  182 . The core print  182  extends into the mold sand. The core print  182  also forms a portion of the opening  46  in the outer wall  50  of the tension member  42 .  
     [0060]FIG. 13 shows a bottom perspective view of the left tension member core module  126 . Extending from the core print  182  is a protrusion  184 . The protrusion  184  is preferably located along the outer edge  186  of the core print  182  nearest the bolster opening bottom core module  128 .  
     [0061] The left tension member core module  126  also has a side window core print  188  that extends into the mold sand of the drag mold. The core print  188  extends from the underside of left side window portion  166 . The top perimeter  34  of the left side window  32  of the side frame  14  preferably has no outside corner radius as shown in FIG. 18.  
     [0062] As shown in FIG. 17, prior art sideframes had outside corner radii  190  at the perimeter of their side window  192 . The core print  194  had to stop at the radius tangent point  193 , and could not extend into the mold sand. As those skilled in the art will appreciate, if the core print attempted to form the outside radius, where the core print hole perimeters are parallel to the corebox parting line, a ledge is created when forming the core module in the core box. This will prevent the core module from being removed from the corebox. Thus, in prior art designs, the core print stopped at the beginning of the outer hole radii. This prior art core does not locate the core module with respect to the mold.  
     [0063] The top perimeter  34  without the outside corner radius of the present invention shown in FIG. 18 permits core print  188  to extend into the mold sand. Because there is no outside corner radius, no ledge will be formed when making the core module, thus permitting it to be removed from the core box. Moreover, the core print  188  together with the core print  182  and protrusion  184  extending into the mold sand primarily locates the left tension member core module in the drag mold sand.  
     [0064]FIG. 8 shows the left column wall core module  134  inserted into the cavity  172  of the left tension member core module  126 . The left column wall core module  134  forms the interior wall of the left column wall  24 . The right column wall core module  136  is similarly inserted into a cavity in the right tension member core module  130 .  
     [0065]FIGS. 15 and 16 show the bolster opening bottom core module  128  in the bolster opening design zone  90 . The bolster opening bottom core module  128  forms internal surfaces of the bolster opening bottom section  78 . Preferably, the bolster opening bottom core module  128  forms the entire interior surface of the bolster opening bottom section  78  on both sides of the central longitudinal plane  114  of the sideframe  14 . The bolster opening bottom core module  128  preferably has left and right core prints  196  and  198 . The left and right core prints  196  and  198  extend into the mold sand to locate the bolster opening bottom core module  128  in the mold. The left core print  196  combines with the core print  182  of the left tension member core module  128 , and forms a portion of the opening  46  in the outer wall  50  of the tension member  42 . The right core print  198  does the same with the right tension member core module  130 .  
     [0066] As shown in FIG. 16, the left and right ends  200  and  202  of the bolster opening bottom core module  128  have shelves  204  and  206 . The left shelf  204  mates with the weight bearing surface  180  of the left tension member core module  126 . Similarly, the right shelf  206  mates with a weight bearing surface of the right tension core module  130  such that the weight of the bolster opening bottom core module  126  is partially supported by the left and right tension member core modules  126  and  130 . Where the bolster opening bottom core module  128  and left tension member core module  126  meet, a joint  195  is formed. Where the bolster opening bottom core module  128  and right tension member  130  meet a similar joint  197  is formed.  
     [0067] The left and right core prints  196  and  198  of the bolster opening bottom core module  128  preferably have protrusions  208  and  210  extending from their undersides at their outer edges  212  and  214 . Protrusions  208  and  210  are preferably rectangular, and together with the left and right core prints  196  and  198 , primarily locate the bolster opening bottom core module  128  in the mold.  
     [0068] The bolster opening design zone  90  may also include a bolster opening core module  216  and a spring seat core module  218  (FIG. 19). The bolster opening core module  216  preferably defines a portion of the top compression member  52  in the bolster opening design zone  90 , and the external surfaces of the left and right column walls  24  and  22 . The spring seat core module  218  defines internal surfaces of the spring seat  102 .  
     [0069]FIG. 14 shows a central transverse plane  120  of the sideframe  14 . The central transverse plane  120  divides the sideframe  14  into left and right halves  122  and  124 . As shown in FIG. 14, the joints  177 ,  179 ,  195 , and  197  are preferably parallel to the central transverse plane  120  of the sideframe  14 .  
     [0070] Corebox tooling costs are a significant portion of producing sideframe castings. To minimize production costs, core production machines and coreboxes must be used to their full potential. This must be done while maintaining design flexibility. In the freight car market, each customer has a particular set of sideframe casting design requirements. To economically meet customer design requirements, core production tooling should be designed so portions are interchangeable. This minimizes customer driven tooling change costs. It also reduces the complexity of design changes, the number of corebox changes on the core production line, and the corresponding tooling changes.  
     [0071] The core modules  123  of an embodiment of the present invention provides great flexibility in the manufacture of sideframes  14 . For instance, suppose a customer orders a sideframe  14 , but desires a change made only to the sideframe in the left and right outer leg design zones  86  and  94 , but keeps the rest of the design intact. Only the left and right outer leg core modules  124  and  132  need to be changed. The remaining core modules need not be changed. Corebox and tooling changes are only required for the core module that is changed.  
     [0072] Moreover, modular coreboxes can be used such that design changes occurring in a core module require only portions of the corebox to be changed. This way the same basic tooling can be used without having to build an entirely new corebox to accommodate the change.  
     [0073] It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.