Abstract:
In a process for the assembly of wax trees, a wax runner is placed in a flat position, and a wax pattern is located adjacent to the wax runner. Both the wax pattern and the wax runner are heated and then placed in contact with one another where heated. Then the wax pattern and the wax runner are separated slightly to form a fillet weld between the wax pattern and the wax runner. An apparatus is also provided which, by robotics, brings a multiplicity of wax patterns to a wax runner and which automatically heats both the wax patterns and the wax runner before simultaneously pressing both the wax patterns and the wax runner together. Once a wax tree assembly is completed, a new wax runner replaces the wax runner that has been formed into a wax tree, and additional wax patterns are affixed in the same manner.

Description:
RELATED APPLICATION 
   This application is a divisional of co-pending parent U.S. patent application Ser. No. 10/304,840, filed Nov. 26, 2002, and accordingly priority is claimed for this divisional application based upon Provisional Application 60/333,526, filed Nov. 28, 2001, upon which co-pending parent U.S. patent application Ser. No. 10/304,840 is based. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to the Lost Wax Process of casting and more specifically to a process and apparatus for the assembly of a wax tree. 
   2. Prior Art and Objects 
   The Lost Wax Process of casting is a widely used and well-know process. Basically, a wax pattern is formed by wax injection molding. Then, a multiplicity of the wax patterns, each of which includes a gate, is affixed to a runner creating a wax tree assembly. Then, ceramic is spread over the wax tree assembly. The resulting ceramic shell is then heated to melt the wax and the wax is thus removed from within the ceramic shell. Molten material, usually a metal, is then poured into the ceramic shell. Upon hardening, the ceramic is broken away and the desired castings are removed from the cast version of the runner. 
   The Lost Wax Process is a highly labor intensive procedure, but in more recent times, the wax pattern production, ceramic buildup and metal pouring have been successfully automated. The wax tree assembly, however, has remained a labor intensive operation. Furthermore, wax tree assembly requires artistic abilities on the part of the wax tree assembler. Even an experienced and artistic assembler cannot avoid improper connections which result in rejected castings. 
   It has been recognized that the most desirable fusion between the gate of the wax pattern and the wax runner is a fillet weld which is similar to the well-known fillet welds used in metal welding. However, despite the great need, the technique for readily achieving fillet weld fusion in wax tree assembly has not been previously known. 
   Various techniques have been proposed to automate the assembly of the wax tree assembly. One proposal, which apparently originated in Japan, places the gate of the wax patterns into a recessed surface of the wax runner and then molten wax is poured into the recessed area to fuse the wax pattern to the runner. The resulting fusion does not provide the desired fillet weld between the runner and the gate of the wax pattern and the poured wax does not possess the quality of the original molded wax of the runner. This method is also a manual operation and it does not appear to be an operation that offers a realistic basis for automation. 
   Wax Tree Assembly Machines have also been developed both in the United States and in Russia but both attach wax patterns to a runner that is held sideways. This results in potential dripping problems which can damage the wax pattern. 
   Therefore, it is an object of this invention to develop a process by which a highly acceptable bond between the gate of a wax pattern and a runner can be achieved. 
   It is a further object of this invention to provide an automated process for connecting the gate of a wax pattern to a runner. 
   It is a further object of this invention to provide a process for the assembly of wax trees that is economical and dependable. 
   It is further object of this invention to provide a process for the assembly of wax trees that produces a high rate of acceptable castings. 
   It is still another object of this invention to provide an apparatus to effectuate the successful operation of an automated process for the assembly of wax tree assemblies. 
   It is still another object of this invention to provide an apparatus that accurately and repeatedly produces a wax tree assembly. 
   It is a further object of this invention to provide an apparatus for the production of wax tree assemblies that is durable and dependable. 
   These and other objects and advantages of the present invention will become apparent to those of ordinary skill in the art as the description thereof proceeds. 
   SUMMARY OF THE INVENTION 
   A process for the assembly of wax trees is disclosed in which a wax runner is placed in a horizontal position. A wax pattern is placed in close proximity to the wax runner with the wax runner aligned with the wax pattern. Heat is applied to the wax pattern and to the wax runner. The wax runner and the wax pattern are placed into contact where the heat was applied and then the wax runner and the wax pattern are slightly separated from one another to form a fillet weld. 
   An apparatus is also provided for assembling a wax tree from a wax runner and a plurality of wax patterns. The apparatus includes a runner load station for holding a wax runner. A pattern loading table is located adjacent the runner load station f for holding the wax patterns. A pattern assembly includes a pattern fixture for gripping the wax patterns which are located on the pattern loading table. The pattern assembly further includes a means for moving the wax patterns gripped by the pattern fixture to a location adjacent to the wax runner. A heating assembly is included with a heating device and means for heating the heating device to a temperature sufficient to melt wax. The heating assembly further includes means for moving the heating device between the wax runner and the wax patterns to melt surface wax on the wax runner and the wax patterns and to remove the heating device when wax melting has occurred. The pattern assembly still further includes means to bring the wax patterns and wax runner together where wax has been melted by the heating device. 

   
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  through  FIG. 1D  show the steps which are used to affix a wax pattern to a wax runner to form a wax tree with the wax patterns and the wax runner joined by fusion in the form of a fillet weld. 
       FIG. 2  is a pictorial view of a wax tree with the wax patterns affixed by a fusion in the form of a fillet weld. 
       FIG. 3  is a pictorial view of an apparatus to affix automatically multiple wax patterns to a wax runner. 
       FIG. 4  is a top plan view of the same apparatus shown in  FIG. 3 . 
       FIG. 5  is a side view of the same apparatus shown in  FIG. 3 . 
       FIG. 6  is a side view of only the cleaning station and a part of the heating assembly from the opposite side shown in  FIG. 5 . 
       FIG. 6A  is a side view of only the cleaning station as shown in  FIG. 6  but with the Heating Assembly removed to show the slot in the cleaning station. 
       FIG. 7  is pictorial view of the runner load station partially broken away with the covers removed to show the upper shafts and the lower shaft and the pulley wheels and the pulley belts. 
   

   DETAILED DESCRIPTION OF THE NUMERALS 
   
     
       
             
             
           
         
             
                 
             
             
               NUMERAL 
               DESCRIPTION 
             
             
                 
             
           
           
             
               11 
               Wax Pattern 
             
             
               13 
               Wax Runner 
             
             
               15 
               Fillet Weld 
             
             
               16 
               Wax Tree Assembly 
             
             
               17 
               Wax Pattern Gate 
             
             
               18 
               Pour Cup 
             
             
               19 
               Heated Blade 
             
             
               21 
               Base 
             
             
               23 
               Frame 
             
             
               25 
               Two Vertical Supports 
             
             
               27 
               One Horizontal Support 
             
             
               29 
               Pattern Loading Table 
             
             
               31 
               Centerline 
             
             
               33 
               Shaft 
             
             
               37 
               Runner Load Station 
             
             
               41 
               Wax Runner Holders 
             
             
               43 
               Holder Assembly 
             
             
               44 
               Pair of Upper Shafts 
             
             
               45 
               Rotation Motor 
             
             
               47 
               Lower Shaft 
             
             
               49 
               Lower Pulley Wheels 
             
             
               51 
               Upper Pulley Wheels 
             
             
               53 
               Pulley Belts 
             
             
               55 
               Pivot Axle 
             
             
               56 
               Rod 
             
             
               57 
               Pattern Assembly 
             
             
               59 
               Vertical Lifter Member 
             
             
               61 
               Horizontal Lifter Member 
             
             
               63 
               Horizontal Delivery Member 
             
             
               65 
               Lower End 
             
             
               67 
               Pattern Fixture 
             
             
               69 
               Pattern Trays 
             
             
               71 
               Outside Pattern Tray 
             
             
               73 
               Inside Pattern Tray 
             
             
               75 
               Heating Assembly 
             
             
               76 
               Heating Device 
             
             
               79 
               Lower horizontal Blade Member 
             
             
               81 
               Connector 
             
             
               83 
               Vertical Knife Member 
             
             
               85 
               Horizontal Heating Retraction Member 
             
             
               87 
               Horizontal Heating Member 
             
             
               89 
               Cleaning Station 
             
             
               91 
               Slot 
             
             
               93 
               Air jets 
             
             
               95 
               Controls 
             
             
                 
             
           
        
       
     
   
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to  FIGS. 1A through 1D , the fundamental steps are shown, whether performed by a manual process of affixing just one wax pattern  11  at a time or performed by an automated process. In the attachment of a wax pattern  11  to a wax runner  13 , the most desirable resultant form of fusion between the wax pattern  11  and the wax runner  13  is a fillet weld  15 . Examples of a fillet weld  15  are shown in  FIG. 1D  and in  FIG. 2 . The fillet weld  15  is analogous to a fillet weld, as that term is used in the art of welding. In  FIG. 2 , the wax patterns  11  are shown affixed to the wax runner  13  forming a wax tree assembly  16 . The fillet weld  15  is a rounded concave bead between the wax runner  13  and the wax pattern gate  17  of the wax pattern  11 . The wax tree assembly  16  formed by the attachment of wax patterns  11  to the wax runner  13  is coated with ceramic. The wax runner  13  includes a pour cup  18 . After the wax is removed from the ceramic mold and metal is cast in the ceramic mold, the rounded edge of the ceramic mold, which is the result of the fillet weld  15 , vastly enhances the successful casting of the metallic part. The casting metal is poured through a pour cup, formed in the ceramic from the pour cup  18  of the wax runner  13 . The fillet weld  15  also provides a strong bond between the wax pattern gate  17  of the wax pattern  11  and the wax runner  13 . 
   Referring back to  FIG. 1A , the wax pattern  11  and the wax pattern gate  17  are aligned so that the wax pattern gate  17  of the wax pattern  11  will be properly aligned with the surface of the wax runner  13 . Before any fusion can occur, some bonding procedure must be used that is capable of bonding between the wax pattern gate  17  of the wax pattern  11  and the wax runner  13 . Sticky wax can be applied to the wax pattern gate  17  and to the wax runner  13 . A torch or heat gun may be used to heat the end of the wax pattern gate  17  and the surface of the wax runner  13 . The preferred technique is to use a heated blade  19 . The heated blade  19  may range from a simple putty knife heated on a Bunsen Burner to an electrically heated copper bar. The heated blade  19  may be brought into direct contact with the gate  17  and the wax runner  13  or it may be brought adjacent to the gate  17  and the wax runner  13  without actual contact. In the latter situation, a higher temperature for the heated blade  19  and a longer time is needed to provide the necessary melting without direct contact, but the heated blade  19  does not require cleaning when there is no contact. However, of all the possible means to heat the wax pattern gate  17  and the wax runner  13 , the use of a heated blade  19  in direct contact is preferred. 
   As seen in  FIG. 1B , the gate  17  and the wax runner  13  are both placed in direct contact with the heated blade  19 . Then, as shown in  FIG. 1C , the gate  17  of the wax pattern  11  and the wax runner  13  are brought together to create fusion after the heated blade  19  has been withdrawn. Once fusion is achieved and while the wax is still molten, the wax pattern gate  17  and the wax runner  13  are ever so slightly separated to form the desired fillet weld  15 . Then, the wax is permitted to harden with the fillet weld  15  undisturbed. 
   The ever so slight separation in more definitive terms is approximately within a general range of ten one thousandths of an inch to sixty one thousandths of an inch depending upon the size of the wax pattern  11 . This ever so slight withdrawal that produces a fillet weld  15  adds to the existing manual techniques and automation of the assembly of wax trees, as subsequently described herein, a technique for producing a superior bonding between wax patterns  11  and wax runners  13 . It is also a process that is adaptable for use in an automated process performed by an automated apparatus. 
   Referring now to  FIG. 3  and  FIG. 4 , an apparatus is shown for performing the process and for automatically performing the process. The apparatus is mounted upon a base  21 . A frame  23 , including two vertical supports  25  and one horizontal support  27 , is located to one side of the base  21 . 
   As best seen in  FIG. 4  a pattern loading table  29 , which is rotatable, is shown. Wax patterns  11  are placed on the pattern loading table  29  just outside the centerline  31  of the pattern loading table  29 . The pattern loading table  29  rotates to place the wax patterns  11  just inside the centerline  31 . The pattern loading table  29 , which is circular, rotates about a shaft  33  mounted at the center point of the table  29  ( FIGS. 3 and 5 ). 
   A runner load station  37  is mounted to rotate about the centerline of a wax runner  13 . The wax is held by a pair of wax runner holders  41  which form a holder assembly  43 . ( FIGS. 4 and 5 ) A rotation motor  45 , when actuated, rotates the holder assembly  43  within the runner load station  37 . Since the wax runners  13  are made of wax, they do not have substantial strength. Therefore, at the bottom of the runner load station  37  there is a lower shaft  47 . On the opposite ends of the lower shaft  47  are a pair of lower pulley wheels  49 . Upper pulley wheels  51  are mounted on the pair of upper shafts  44 . Each of the upper pulley wheels  51  are vertically aligned with one of the lower pulley wheels  49  and each of the aligned upper pulley wheels  51  and lower pulley wheels are connected by a pulley belt  53 . At the end of the upper shaft  44  toward the frame  29 , the rotation motor  45  is mounted which drives the upper shaft  44 . In this way, the upper shaft  44 , not connected directly to the rotation motor  45 , is driven through the lower shaft  47  and the pulley belts  53 . As a result, wax runner holders  41  are both simultaneously driven by the rotation motor  45  to assure that no twisting or other stress occurs in the wax runner  13 . 
   The pair of wax runner holders  41  are located generally in line with the pattern loading table  29 . In  FIGS. 3 and 4 , the wax runner  13  is shown being held by the pair of wax runner holders  41 . As seen in  FIGS. 4 and 5 , the runner load station  37  is mounted on a pivot axle  55 . This permits the runner load station  37  to tilt substantially at a right angle to the upper shafts  44  and to the lower shaft  47 . A rod  56  is provided to tilt the runner load station  37  on the pivot axle  55 . Wax runners, on occasion, are tapered and it is essential that the surface of the wax runner  13  be level. By tilting the runner load station  37 , the surface of the wax runner  13  held within the pair of wax runner holders  41  is placed in a level position. 
   As best seen in  FIG. 3 , but which is also shown in  FIGS. 4 and 5 , a pattern assembly  57  is mounted on the base  21  to be accessible to the pattern loading table  29 . The pattern assembly  57  includes a vertical lifter member  59 , a horizontal lifter member  61  and a horizontal delivery member  63  all of which are supported by the frame  23 . The pattern assembly  57  is a three-dimensional device. 
   The vertical lifter member  59  moves up and down essentially in a position perpendicular to the base  21 . The horizontal lifter member  61  moves the vertical lifter member  59  across the base  21  from the pattern loading table  29  toward the frame  23 . The horizontal delivery member  63  moves the vertical lifter member  59  from the pattern loading table  29  to the runner load station  37  and, more specifically, the horizontal lifter member  61  and the horizontal delivery member  63  place the vertical lifter member  59  directly over the wax runner  13  held by the wax runner holders  41  within the runner load station  37 . 
   The vertical lifter member  59  has a lower end  65  closest to the base  21 . Mounted on the lower end  65  of the vertical lifter member  59  is a pattern fixture  67 . The pattern fixture  67  grasps the wax patterns  11  opposite the point where the wax patterns  11  are attached to the wax runner  13 . Within the pattern fixture  67  are a plurality of pattern holders (not shown). Frequently, each wax pattern  11  requires a pattern holder that is specific to that specific wax pattern  11 . In certain cases, a pattern holder may be adaptable to a limited variety of similar wax patterns  11  but wax patterns  11  must be carefully held without any possible deformation of the wax pattern  11 . The series of pattern holders in the pattern fixture  67  holds a plurality of wax patterns  11  in a linearly spaced relationship. Pattern holders of various types and sizes are known and are available. A pattern fixture  67  is, in essence, a specialized clamp that positively holds the wax pattern  11  without deforming it. 
   The pattern loading table  29  has mounted upon it a pair of pattern trays  69 . The pattern trays  69  are located on opposite sides of the shaft  33  on which the pattern loading table  29  rotates. The pattern trays  69  are substantially parallel to one another and equidistant from the shaft  33 . Thus, when the pattern loading table  29  is rotated one hundred eighty degrees, the pattern tray  69  originally closest to the runner load station  37  is moved away form the runner load station  37  and the pattern tray  69 , previously remote to the runner load station  37 , is moved closest to the runner load station  37 . Whichever of the pattern trays  69  is most remote from the runner load station  37  is the outside pattern tray  71 , while the pattern tray  69  closest to the runner load station  37  is the inside pattern tray  73 . 
   Each pattern tray  69  retains a plurality of wax patterns  11  in a spaced relationship consistent with the spaced relationship of the pattern holders when held by the pattern fixture  67  which is the desired spaced relationship for the wax patterns  11  when mounted on the wax runner  13 . As a result, the attachment of wax patterns  11  to the wax runner  13  is extremely precise, resulting in a wax tree assembly  16  that is far superior to a wax tree that possibly could be achieved by a manual process. 
   A heating assembly  75  is also mounted on the frame  23  where the pattern assembly  57  is located. The heating assembly  75 , when not is use to melt surface wax on the wax runner  13  and the wax pattern  11 , but during operation, is located above and to one side of the runner load station  37  opposite from the pattern loading table  29 . The heating assembly  75 , as shown in  FIGS. 3 ,  4  and  5 , includes a heating device  76  which is shown as a heated blade  19 . The heated blade  19  is preferably electrically heated. The heated blade  19  is connected to a lower horizontal blade member  79  by a connector  81  which permits rapid removal and replacement. Other means may also be utilized for the heating device  76 . The heating assembly  75  further includes a vertical knife member  83  which both raises the heating device  76  upward away from the runner load station  37  and lowers the heating device  76  toward the runner load station  37 . A horizontal heating retraction member  85  moves the heating device  76  to and from the runner load station  37  and the frame  23 . A horizontal heating member  87  moves the heating device  76  across the runner load station  37  toward the pattern loading table  29  and back to the side of runner load station  37  opposite the pattern loading table  29 . Like the pattern assembly  57 , the heating assembly  75  is a three-imensional device. 
   Located beneath the pattern loading table  29  is a cleaning station  89 . Any gas could be used, but most likely air would be used in the cleaning station  89 . The term “air” as used herein, including the claims, means any gas stream. 
   When the heated blade  19  is used in direct contact with the wax pattern  11  and the wax runner  13  to produce wax melting, wax deposits form on the heated blade  19 . Excessive deposits of wax on the heated blade  19  result in lost quality of the wax tree assembly unless the heated blade  19  is cleaned on a regular schedule. The preferred schedule is to clean the heated blade  19  after each wax tree assembly  16  is completed. A slot  91  is provided in the cleaning station  89  at the end closest to the frame  23 . After each wax tree assembly  16  is complete, the heated blade  19  is inserted into the slot  91  by the vertical knife member  83 , the horizontal heating retraction member  85  and the horizontal heat member  87 . Inside the cleaning station  89  are a plurality of air jets  93  which blast air against the heated blade  19  and force the accumulated wax from the heated blade. Whenever the heated blade  19  is not operating, it is stored in the slot  91  in the cleaning station to prevent the heated blade being inadvertently touched by an operator. 
   The multi-directional equipment used in the pattern assembly  57  and in the heating assembly  75 , as well as the controls  95  for the pattern loading table  29  and runner load station  37 , are available commercially. 1  Accordingly, a detailed explanation of these devices is not included herein.  1.  Automated multi-directional devices can be customized from products produced by Adept Technology, Inc., 3011 Tread Drive, Livermore, Calif. 
   As best seen in  FIGS. 3 and 5 , wax patterns  11  are placed in the outside pattern tray  71  on the pattern loading table  29 . The pattern loading table  29  is outside the centerline  31 . The pattern loading table  29  is rotated a half revolution, one hundred eighty degrees. This changes the outside pattern tray  71  into being the inside pattern tray  73 . The outside pattern tray  71  may be automatically loaded from the equipment producing the wax patterns  11  or the outside pattern tray  71  may be loaded manually. The controls  95  for use by an operator are located adjacent the outside pattern tray  71  which is the location for the operator. 
   As still shown in  FIGS. 3 and 5 , the pattern fixture  67  on the vertical lifter member  59  picks up wax patterns  11  from the inside pattern tray  73 . The vertical lifter member  59  raises the wax patterns  11  held by the pattern fixture  67 . The horizontal lifter member  61  and the horizontal delivery member  63  move the pattern fixture  67  to the desired location over the wax runner  13  held by the wax runner holders  41 . The wax runner  39  must first be placed in the runner load station  37  and the wax runner  13  must be held by the pair of wax runner holders  41  which must hold the wax runner  13  level using the pivot axle  55 . 
   The vertical lifter member  59  is lowered within close proximity to the wax runner  11 . The heating assembly  75  moves the heated blade  19  into contact with the wax pattern  11  and the wax runner  13  to melt surface wax on both the wax pattern  11  and the wax runner  13 . The heated blade  19  is withdrawn by the heating assembly  75 . The wax patterns  11  are lowered by the vertical lifter member  59  so that the heated portions of the wax runner  13  and the wax patterns  11  are in contact. The vertical lifter member  59  then moves slightly upward to withdraw the wax patterns  11  from the wax runner  13  just sufficiently to form a fillet weld  15  between the wax runner  13  and the wax patterns  11 . 
   Once a wax runner  13  has had a full compliment of wax patterns  11  attached to it, the wax runner  13  is replaced with another wax runner  13  in the runner load station  37 . When only one side of a wax runner  13  has been completed, the wax runner  13  is turned over by the rotation of the pair of runner holders  41  as previously described. Also, the heated blade  19  is inserted into the slot  91  in the cleaning station  89  for cleaning afters each wax runner  13  has been completed on both sides. 
   The apparatus shown in  FIGS. 3 and 4  performs a repeatable process with predictable, high quality results. The cost of the automated operation is reduced and permits connecting the apparatus to an automatic wax pattern production apparatus (not shown) for continuous uninterrupted production of wax tree assemblies  16 . 
   The use of the automated apparatus shown in  FIGS. 3 ,  4  and  5  produces highly accurate spacing of the wax patterns  11  and forms the desired fillet welds  15 . 
   It is to be understood that the drawings and description matter are in all cases to be interpreted as merely illustrative of the principles of the invention, rather than as limiting the same in any way, since it is contemplated that various changes may be made in various elements to achieve like results without departing from the spirit of the invention or the scope of the appended claims.