Method of forming a casting mold pattern

Abstract

A method of forming a casting mold pattern that includes a core comprises mounting the core in a fixture such that the core is free of flexing imposed by the fixture. Material is removed from and/or added to a first and/or second mounting surface of the core. The core is then positioned in a die, and wax is conducted into the die to form the pattern. The amount of material removed from the first and/or second mounting surface is such that the core will be within a predetermined range of acceptable positions when the core is in the die with the first mounting surface engaging a first core locating surface of the die end with the second mounting surface engaging a second core locating surface of the die. The range of acceptable positions is determined relative to an ideal position of an ideal core.

Having described the invention, the following is claimed: 
     
         1 . A method of forming a casting mold pattern that includes a core, the core having a length, a first end, and a second end, the second end being spaced apart from the first end by the length, the core also having a first mounting surface adjacent the first end of the core and a second mounting surface adjacent the second end of the core, said method comprising the steps of:
 (a) removing material from and/or adding material to the first mounting surface and/or the second mounting surface:   (b) positioning the core in a pattern forming die alter removing material from and/or adding material to the first mounting surface and/or the second mounting surface, the pattern forming die having a first core locating surface to support the first end of the core and a second core locating surface to support the second end of the core, the core being positioned in the pattern forming die with the first mounting surface in engagement with the first core locating surface and with the second mounting surface in engagement with the second core locating surface; and   (c) conducting a flow of wax into the pattern forming die to form a casting mold pattern while the core is positioned in the pattern forming die with the first mounting surface in engagement with the first core locating surface and with the second mounting surface in engagement with the second core locating surface,
 the material being removed from and/or added to the first mounting surface and/or the second mounting surface being in an amount such that the core will be within a predetermined range of acceptable positions when the core is positioned in the pattern forming die with the first mounting surface in engagement with the first core locating surface and with the second mounting surface in engagement with the second core locating surface, the predetermined range of acceptable positions being determined relative to an ideal position in the pattern forming die of an ideal core. 
   
     
     
         2 . The method of  claim 1  further comprising the step of supporting the core such that the core is free of externally applied flexing, the step of removing material from and/or adding material to the first mounting surface and/or the second mounting surface including removing material from and/or adding material to the first mounting surface and/or the second mounting surface while supporting the core such that the core is free of externally applied flexing. 
     
     
         3 . The method of  claim 2  wherein the step of supporting the core such that the core is free of externally applied flexing comprises mounting the core in a fixture such that the core is free of flexing along the length of the core imposed by the fixture. 
     
     
         4 . The method of  claim 3  wherein the fixture has a first gripping device and a second gripping device, the first gripping device being spaced apart from the second gripping device and being able to rotate relative to the second gripping device, the step of mounting the core in a fixture including (i) mounting the core with the first gripping device gripping the core adjacent the first end and with the second gripping device gripping the core adjacent the second end and (ii) permitting the first gripping device and the first end of the core to rotate relative to the second gripping device and the second end of the core so that the core is free of flexing along the length of the core imposed by the fixture. 
     
     
         5 . The method of  claim 4  also comprising the step of locking the first gripping device against rotation relative to the second gripping device after the first gripping device and the first end of the core have been allowed to rotate relative to the second gripping device and the second end of the core. 
     
     
         6 . The method of  claim 1  wherein the core has a twist along its length 
     
     
         7 . The method of  claim 1  wherein the first mounting surface is one of a plurality of first mounting surfaces and wherein the first core locating surface is one of a plurality of first core locating surfaces, the step of positioning the core in a pattern forming die including positioning the plurality of first mounting surfaces in engagement with the plurality of first core locating surfaces. 
     
     
         8 . The method of  claim 1  wherein the core has a convex major side surface extending from a tip end portion of the core to a root end portion of the core, the core also having a concave major side surface extending from the tip end portion of the core to the root end portion of the core, the concave major side surface being spaced apart from and presented in a direction away from the convex major side surface. 
     
     
         9 . The method of  claim 1  wherein the core is molded from a ceramic material and fired at an elevated temperature before removing material from and/or adding material to the first mounting surface and/or the second mounting surface. 
     
     
         10 . The method of  claim 1  wherein the pattern forming die includes a first die section and a second die section, the pattern forming die being in a closed condition to receive and contain the flow of wax when the second die section is moved toward and into contact with the first die section, the pattern forming die being in an open condition to receive the core when the second die section is moved away from and out of contact with the first die section. 
     
     
         11 . The method of  claim 1  wherein the first and second core locating surfaces are fixed in position relative to the pattern forming die. 
     
     
         12 . The method of  claim 1  wherein the step of removing material from and/or adding material to the first mounting surface and/or the second mounting surface consists of removing material from the first mounting surface and/or the second mounting surface. 
     
     
         13 . A method of adjusting a core to be at least partially covered by wax to produce a casting mold pattern, the core having a length, a first end, and a second end, the second end being spaced apart from the first end by the length, the core also having a first mounting surface adjacent the first end of the core and a second mounting surface adjacent the second end of the core, said method comprising the steps of:
 (a) mounting the core in a fixture such that the core is free of flexing along the length of the core Imposed by the fixture; and   (b) removing material from the first mounting surface and/or the second mounting surface;
 the material being removed from the first mounting surface and/or the second mounting surface being in an amount such that the core will be within a predetermined range of acceptable positions when the core is positioned in a pattern forming die with the first mounting surface in engagement with a first core locating surface of the pattern forming die and with the second mounting surface in engagement with a second core locating surface of the pattern forming die, the predetermined range of acceptable positions being determined relative to an ideal position in the pattern forming die of an ideal core. 
   
     
     
         14 . The method of  claim 13  wherein the fixture has a first gripping device and a second gripping device, the first gripping device being spaced apart from the second gripping device and being able to rotate relative to the second gripping device, the step of mounting the core in a fixture including (i) mounting the core with the first gripping device gripping the core adjacent the first end and with the second gripping device gripping the core adjacent the second end and (ii) permitting the first gripping device and the first end of the core to rotate relative to the second gripping device and the second end of the core so that the core is free of flexing along the length of the core Imposed by the fixture. 
     
     
         15 . The method of  claim 14  also comprising the step of locking the first gripping device against rotation relative to the second gripping device after the first gripping device and the first end of the core have been allowed to rotate relative to the second gripping device and the second end of the core. 
     
     
         16 . The method of  claim 13  wherein the core has a convex major side surface extending from a tip end portion of the core to a root end portion of the core, the core also having a concave major side surface extending from the tip end portion of the core to the root end portion of the core, the convex major side surface being spaced apart from and presented in a direction away horn the concave major side surface. 
     
     
         17 . The method of  claim 13  wherein the core is molded from a ceramic material and fired at an elevated temperature before being mounted in the fixture. 
     
     
         18 . A fixture for adjusting a core to be at least partially covered by wax to produce a casting mold pattern, the core having a length, a first end, and a second end, the second end being spaced apart from the first end by the length, the core also having a first mounting surface adjacent the first end of the core and a second mounting surface adjacent the second end of the core, said fixture comprising:
 (a) a first gripping device configured and dimensioned to grip the core adjacent its first end;   (b) a second gripping device configured and dimensioned to grip the core adjacent its second end, the first gripping device being spaced apart from the second gripping device and being able to rotate relative to the second gripping device; and   (c) a locking device for locking the first gripping device against rotation relative to the second gripping device.   
     
     
         19 . The fixture of  claim 13  wherein the first gripping device includes
 (i) a support that maintains a fixed rotational position relative to the second gripping device, and 
 (ii) a carriage pivotally mounted on the support for pivotal movement relative to the support and the second gripping device, the locking device locking the carriage against pivotal movement relative to the support and the second gripping device. 
 
     
     
         20 . The fixture of  claim 19  wherein the first gripping device also includes a support surface carried by the carriage for engaging and supporting a surface of the core opposite the first mounting surface.