Patent Publication Number: US-11020791-B2

Title: Ceramic pour cup assembly and method of forming such an assembly

Description:
FIELD OF THE INVENTION 
     The present invention relates to a ceramic pouring cup assembly and to a method of forming and using such an assembly. 
     BACKGROUND 
     Ceramic pouring cups have been used in the investment casting industry as a metal receptacle since the early 1960s. The ceramic cups are fitted to wax assemblies and then ceramic shelled to provide the assembly with a hard, predefined, ceramic catch basin for molten metal. The lost wax casting process has continued to progress to larger and larger mold assemblies, where the manual handling of the molds has become difficult to accommodate. 
     To accommodate these increases in weight, the investment casting industry has created side handling features to allow the cup to be lifted without the need for manual handling. One solution has involved attaching tubes to the side of cups and gluing them in place with a ceramic bonding agent. An alternative method has been to place the ceramic pour cup into a wax die and then inject wax around the cup, thereby creating a lifting feature that can then be subsequently ceramic shelled. A further example has sought to mold the actual features directly onto the pouring cup. Each of these concepts has a cost associated with the additional process. In the case of tube assembly, there is an element of labour and a potential level of inaccuracy due to variability of the gluing process. In the case of injecting wax around the ceramic cup and then shelling the features, there is a level of time needed to inject the component, which utilises expensive equipment and manual labour. The process of molding the features onto the ceramic cup creates at the outset a difficulty with extra space required in the furnace for sintering and/or in the packing and transportation of the final item. All of these concepts create unwanted extra expenses that become difficult to justify in the manufacturing process of investment castings. 
       FIGS. 1A to 1C  show a plurality of views of a standard pour cup used throughout the investment casting industry without any features for overcoming the difficulties with manual handling.  FIGS. 2A to 2C  show a plurality of views of a ceramic pour cup with lifting features already molded into the final part. While the pour cup of  FIGS. 2A to 2C  permits machine lifting of the assembly, the design of the pour cup does not lend itself to efficient handling. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention seeks to provide an improved ceramic pouring cup assembly and method of forming and using such an assembly. In particular, the present invention seeks to provide an improved pour cup for investment casting. 
     According to an aspect of the present invention, there is provided a pour cup assembly for use in casting, comprising a cup and at least one lifting yoke separately attachable to the cup, the yoke including a body portion and first and second arms extending laterally from the body portion, each arm including a support formation, and a coupling element provided on at least one of the pour cup and the at least one yoke for use in coupling the pour cup and at least one yoke together. 
     The advantage of this arrangement is that the assembly need only be formed at the time of use, allowing transportation in packed form, which can save significantly on transportation and storage costs. In the preferred embodiments a plurality of pour cups can be stacked together, which significantly reduces storage volumes, while the yokes can be flat packed together. In some embodiments, the yokes can be nested within one another, further reducing transportation and storage volumes. 
     The yoke or yokes could also be termed lifting extensions. 
     In an embodiment, the assembly comprises first and second yokes. 
     Advantageously, the pour cup has a frusto-conical shape and the body portion of the or each yoke has a part frusto-conical shape. 
     Preferably, the pour cup and the body portion of the at least one yoke have corresponding shapes so that the pour cup can abut against at least a part of the body portion of the yoke or yokes. This can optimise the connection between the pour cup and at least one yoke and the quality of the subsequent coating or shelling. However, in other embodiments, the pour cup and yoke or yokes need not be a precise match in shape. 
     In some embodiments, the body portion of the at least one yoke has an internal surface with at least two portions designed to accommodate different sized pour cups. 
     Advantageously, the coupling element is a groove on at least one of the pour cup and yoke. At least one groove is preferably provided on each of the pour cup and the at least one yoke. The grooves on the pour cup and the at least one yoke can be aligned with one another. The assembly preferably includes a tie element disposable in the groove or grooves so as to tie the pour cup and at least one yoke together. 
     In an embodiment, the assembly includes two yokes. The yokes can be nested within one another. Preferably, the yokes are substantially identical to one another. 
     In embodiments, the or each yoke has a substantially flat profile. 
     Advantageously, the pour cup and the or each yoke are made of the same material. Examples include ceramic material, alumina, silicate, fused silica and the like. In other embodiments they may be made of different materials. It is preferred that the pour cup and yoke or yokes have the same or similar coefficients of thermal expansion. 
     The use of a ceramic material, or alumina, silicate, fused silica and the like, for making the yokes gives them strength, such that they contribute to the strength of the final assembly. 
     According to another aspect of the present invention, there is provided a method of forming a pour cup assembly including the steps of coupling together a pour cup and at least one yoke, coating or shelling the coupled pour cup and at least one yoke with a cast material to form a unitary pour cup and yoke assembly. 
     Preferably, the pour cup and at least one yoke are coupled together with a tie element. 
     The coating may be by dipping in or spraying or showering with cast material. 
     The cast material may be a ceramic material, a colloidal silica, mullite zircon, fused silica or the like, used in investment casting. 
     Advantageously, the pour cup and at least one yoke are coated multiple times with cast material. 
     Advantageously, the or each yoke has a substantially flat profile. 
     In the preferred embodiment, there are provided first and second yokes, disposed or disposable on opposing sides of the pour cup. 
     The or each yoke preferably comprises a portion having a shape conforming to the shape of a part of the cup, thereby to be able to be disposed in close contact with the cup prior to attachment. 
     The or each yoke preferably comprises at least one lifting feature for receiving a lifting element, the lifting feature advantageously being one or two recesses or holes into which a lifting element can be located. 
     The invention also extends to a yoke or lifting extension as disclosed herein. 
     Other aspects and advantages of the teachings herein will become apparent to the skilled person from the description of the preferred embodiments that follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which: 
         FIGS. 1 a    to  1 C show various views of a standard pour cup; 
         FIGS. 2A to 2C  show various views of a ceramic pour cup with lifting features pre-molded into cup; 
         FIGS. 3A to 3D  show various views of an embodiment of pour cup according to the teachings herein; 
         FIG. 4  is a view of the molded yokes of the embodiment of  FIGS. 3A to 3D ; 
         FIG. 5  is a perspective view of another embodiment of lifting yoke for a pour cup assembly; 
         FIG. 6  is a bottom plan view of the embodiment of lifting yoke of  FIG. 5 ; 
         FIG. 7  is a top plan view of an embodiment of pour cup assembly using the yoke of  FIGS. 5 and 6 ; 
         FIG. 8  is a side elevation view of the embodiment of pour cup assembly of  FIG. 7 ; 
         FIG. 9  is a top plan view of another embodiment of pour cup assembly using the yoke of  FIGS. 5 and 6 ; 
         FIG. 10  is a side elevation view of the embodiment of pour cup assembly of  FIG. 9 ; 
         FIG. 11  is an outside perspective view of another embodiment of yoke for a pour cup assembly; 
         FIG. 12  is an inside perspective view of the embodiment of yoke of  FIG. 12 ; 
         FIG. 13  is a front inside elevational view of the embodiment of yoke of  FIGS. 11 and 12 ; 
         FIG. 14  is a perspective view of an embodiment of pour cup assembly using the yoke of  FIGS. 11 to 13 ; and 
         FIG. 15  is a top plan view of the embodiment of pour cup assembly of  FIG. 14 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The teachings herein provide a novel concept of providing lifting features or elements that can be coupled to a pour cup for machine assisted handling of pour cup assemblies for investment casting. The concept aims to remove the variability of current processes and manufacturing methods, while removing significant costs in both the assembly, manufacture and transportation charges associated with such items. 
       FIGS. 3A to 3B  show a pour cup assembly  10 , in the assembled state. The assembly  10  includes a pour cup  12  of frusto-conical shape and which is preferably similar to or the same as pour cups conventionally used in the industry. The cup  12  has an inlet end  14 , of relatively larger diameter, and an outlet  16 , of relatively smaller diameter. The cup  12  may have dimensions consistent with conventional pour cups used in the industry. 
     The assembly  10  also includes two yokes  18 ,  20 , shown in better detail in  FIG. 4 . Each yoke  18 ,  20  includes a body section  22  with a part frusto-conical internal profile and opposing arms  24 ,  26  extending laterally from the body section  22  and that lie in a common plane in this embodiment. Each arm  24 ,  26 , as can be seen better in  FIGS. 3A to 3D , has a bore or hole  30  therein. The arms  24 ,  26  have a thickness D and have a strength sufficient to support the assembly during the manufacture of the investment cast. 
     The body portion  22  has an external profile that, in this embodiment, is also part frusto-conical in shape, as can be seen in particular in  FIGS. 3B to 3D , and in the preferred embodiments one or more circumferential grooves  32  in its outer surface. The groove or grooves  32  preferably extend parallel to the arms  18 ,  20  and transverse to the longitudinal direction of the body portion  22 . The groove or grooves  32  in use accommodate a tie element disposed around the body portion  22  and cup  14  to hold the assembly together while the assembly  10  is subsequently coated with cast material (typically ceramic) to form the unitary pour cup assembly. This is typically done at the same time as creating the investment cast around the invested pattern. 
     The assembly  10  shown in  FIGS. 3A to 3D and 4  uses two yokes  18 ,  20  for symmetry around the pour cup  10 , although in many cases a single yoke may be used, as per the examples provided below. 
     While the embodiments of  FIGS. 3A to 3D and 4  has three grooves  32 , it will be understood that only one groove is required. 
     There may be provided at the facing surfaces of the pour cup  12  and yokes  18 ,  20  an alignment feature, such as a groove and rib or other similar cooperating features. The alignment feature can ensure that the yokes are properly positioned relative to the pour cup prior to tying and coating or shelling. 
     It is preferred that the yoke or yokes  18 ,  20 , as with all of the embodiments taught herein, are formed of the same material as the pour cup  10 , typically a ceramic material, although other materials can be used as taught herein and known in the art. As the assembly  10  is subsequently coated in a cast or shell during the process, the yoke or yokes and the cup could be made of different materials if desired. 
     The arrangement of a pour cup  10  and separate but attachable yoke or yokes  18 ,  20  provides an assembly that can be handled with machine assistance, that can be reliably produced and that can be provided in an efficient manner. Specifically, the assembly can be supplied in disassembled form, packaged in a significantly lesser volume than ready assembled versions (such as that shown in  FIGS. 2A and 2D ), thereby significantly reducing costs. More specifically, a plurality of pour cups  12  can be stacked into one another and the yokes  18 ,  20  flat packed in optimised packaging. The packaging, as well as being space efficient and therefore reducing overall transportation and storage costs, can reduce the risk of damage to the pour cups and yokes/arms. A pre-molded ceramic pouring assembly with the same features would take up a significant amount of space in a transportation pallet. Depending on the size of the cup, this may reduce the available space by up to a half, thereby increasing the associated freight costs by up to two times. This new innovation allows for the individual features to be flat-packed and can reduce both valuable kiln and transportation charges potentially by over 100%. 
     The pour cups and yokes can be removed from the packing and tie-gripped onto the circumference of the standard pour cup design. There is no need for any special glues as the assembly will be shelled and therefore fixed into position during the standard lost wax manufacturing process. 
     It is to be understood that the shape and design of the yokes shown in  FIGS. 3A to 3D and 4  is exemplary only and also that in some applications a single one of the yokes shown may be necessary. 
     Referring now to  FIGS. 5 and 6 , these show another embodiment of yoke  40  for a pour cup assembly. In this embodiment, the yoke  40  has a part frusto-conical body portion  42  and first and second side arms  44 ,  46  on opposing sides of the body portion  42  and lying in a common plane. Each side arm  44 ,  46  has a bore or hole  48  therein for accommodating a lifting rod or mandrel. 
     In this embodiment, the body portion has a length or depth the same as that of the side arms  44 ,  46 . The internal surface of the body portion  42  has two sections, a first  52  having a first tapering radius and a second  54  having a second, larger, tapering radius for purposes explained below. 
     The side arms  44 ,  46  have a thickness D sufficient to be able to support the pour cup assembly on a rod or mandrel without twisting or tipping. A suitable thickness D will be dependent on the particular practical implementation and can be readily determined by a skilled person. 
     As can be seen in particular in  FIG. 6 , the outer surface of the body portion  42  is provided with a circumferential groove  50 , which in this embodiment extends to the holes  48 . The groove  50  can accommodate a tie element (not shown) for tying the yoke  40  to a pour cup temporarily until it is coated or shelled in an investment cast as described herein. 
     Referring now to  FIGS. 7 and 8 , these show the yoke  40  coupled to a pour cup  12  of a first, larger diameter. As can be seen in particular in  FIG. 7 , the pour cup  12  rests against the internal, larger radius, sections  54  of the yoke  40 . The cup  12  includes in this embodiment two circumferential grooves  60 ,  62  which can accommodate a tie element (not shown), typically around both the yoke  40  and the cup  12  and fitting within both the groove  50  in the yoke and one of the grooves  60 ,  62  of the cup  12 . The tie element, as with any embodiment disclosed herein, can be a plastic tie, a cord, a wire or any other suitable element. The tie element can temporarily fasten the pour cup and yoke or yokes together as the subsequent coating or shelling process will form a strong and unitary assembly after which the tie element need not perform any other function. In other embodiments, the pour cup and yoke or yokes could be temporarily tied together by wax or other suitable bonding agent. 
     While there is a gap  70  between the cup  12  and the smaller radius portion  52  of the yoke  40 , this is not material. In practice, the gap  70  will be filled with cast material during the process of making the investment cast, although if it is not this is not material as the investment cast will cover the yoke and cup at least in the portions where they touch one another, forming a strong bond between or envelope around the two components  40 ,  12 . The gaps, however, can allow ceramic or other coating material to bond the parts together at their facing surfaces, and similarly by means of any groove  60 ,  62  at the interface between the pour cup and internal surfaces of the yokes. 
     Referring now to  FIGS. 9 and 10 , the same yoke  40  of  FIGS. 5 and 6  is shown coupled to a smaller diameter pour cup  12 ′. In this arrangement, the pour cup  12 ′ sits against the internal surface of the smaller radius section  52  of the yoke  40 , with gaps  72  between the pour cup  12 ′ and the larger radius section  54  of the yoke  40 . As with the pour cup  12  of  FIGS. 7 and 8 , the pour cup  12 ′ is provided with at least one circumferential groove  64  for receiving a tie element as previously described. 
     The embodiments of  FIGS. 5 to 10  provide a single yoke  40  for the assembly. Preferably, as described, the arms  44 ,  46  of the yoke  40  are sufficiently wide such that a rod or mandrel fitted into the bores or holes  48  will hold the assembly without tilting on the mandrel or rod. 
       FIGS. 12 to 15  show another embodiment of assembly, which uses two yokes  80 , one either side of a pour cup  12 . 
     Referring first to  FIGS. 11 to 13 , in this embodiment the yoke  80  is formed to have a substantially uniform thickness across both its body portion  86  and its arms  82 ,  84 . The body portion  86  is of a part frusto-conical shape and has a uniform tapering radius along its length similar to the embodiment of  FIGS. 3A to 4 . The body portion  86  extends further than the arms  82 ,  84  in the longitudinal direction, as will be apparent in the Figures. 
     The arms  82 ,  84  have a hole  88  therein similar to the other described embodiments, for receiving a lifting rod or mandrel. 
     An external groove  90  is provided in the outer surface of the body portion  86  and in the example shown is located just below the arms  82 ,  84  to as to enable a tie element to wrap around the assembly from the grooves  90  in the two yokes  80  of the assembly and below the arms  82 ,  84 . The grooves  90  could be located elsewhere in the outer surface of the body portion, as in other embodiments. 
     The yoke  80  is of a shape and design that a plurality of such yokes  80  can nest within one another, substantially reducing packaging and storage requirements. 
     Referring now to  FIGS. 14 and 15 , two yokes  80  are disposed on opposite sides of a pour cup  12 , provided with one or more grooves  90 ,  92  in its outer surface for receiving a part of a tie element. It will be apparent that when so assembled, a tie element can be disposed in the grooves  90  of the yokes  80  and also partially along the groove  92 ,  94  so as to hold the assembly together until it is coated or shelled. 
     The provision of a plurality of grooves  90 ,  92  on the pour cup enables the user to select the relative position of the pour cup relative to the arms  82 ,  84  and the holes  88 , as well as the distance between the opposing yokes  80  of the assembly, determined by the taper of the pour cup  12  and how far up or down that taper the yokes  80  are disposed. 
     As two yokes  80  are used in this embodiment, the arms  82 ,  84  can be made thinner as the resistance to tilting on a rod or mandrel is achieved by the use of the two opposing and spaced arms  82 ,  84  of the two yokes  80 . 
     As with the previous embodiments, the assembly is coated or shelled with cast material, typically ceramic, during the production of the investment cast, thereby forming a strong and unitary structure. The coating can be by dipping in a bath of liquid ceramic slurry or by spraying or in any other suitable manner. It will be appreciated that the holes or bores are preferably blocked off during the coating process, or otherwise cleaned after coating. 
     The pour cup and yokes are preferably made to fit standard production processes and machinery. In one example, the overall length (span) of the assembly is in the region of 315 mm. The thickness through the lift holes of the yokes may be in the region of 60 mm for a single yoke arrangement and around 12 mm for a double yoke arrangement. The overall height (that is height to the highest apex point) may be the region of 60 to 140 mm. The hole diameter may be in the region of 35 mm. The assembly may have a product weight of around 1.8 kgs. 
     While the embodiments of  FIGS. 3A to 4 and 11 to 15  provide two yokes that are spaced from one another in the assembled state, it is envisaged that they may touch, that is circumscribe the full circumference of the pour cup when assembled. When spaced, the opposing yokes may have a spacing of around 125 mm between one another. 
     The grooves for the tie elements may have a diameter of around 9 to 10 mm but could be less or more. The grooves in the pour cups can also be used for hanging purposes. 
     While in the embodiments shown the arms have holes, in other embodiments the arms could be provided with a hook for the same purposes. The hook may, for instance, be inverted, that is open at its lowermost end, in the form for instance of an inverted U. 
     It will be appreciated that the features of the different embodiments are interchangeable with one another. 
     The disclosures in British patent application number 1900422.5, from which this application claims priority, and in the abstract accompanying this application are incorporated herein by reference.