Abstract:
An improvement setter and method of operation for maintaining and reconfigurating the shape of a malleable pattern used in molding of parts. The setter includes an arrangement for arranging the pattern against the setter using vacuum.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Wax and other malleable pattern materials such as plastics are produced for use in the production of investment castings. Such patterns are generally produced by injection molding and other molding techniques. Such wax patterns are initially created by injection of liquid wax into aluminum or epoxy molds maintained at a temperature below that of the melting temperature of the wax. After injection the wax is held within the mold cavity for a suitable dwell time to allow for solidification, and thereafter it is removed from the mold. Because wax is a poor thermal conductor, the dwell time for complete cool down to room temperature is usually uneconomic and excessive from a production standpoint. Therefore, the solidified wax patterns are generally removed from such molds while the wax is still warm, and the wax pattern then cools down to room temperature outside of the mold cavity. Removal of warm wax from the mold cavity and such cool down to room temperature outside of the mold cavity subjects the wax to warping, sagging, or cool down, and other forces.  
           [0002]    To minimize such distortion during cool down of warm wax to room temperature, metal setters have been used. Metal setters are positioned in engagement with the patterns to maintain the pattern shape during cooling. Metal setters are positioned in engagement with the patterns to maintain the pattern shape during cooling. Prior setters have used the weight of the pattern with or without additional force or weight applied to the pattern to urge the pattern against the setter. However, prior setters have not operated to accomplish a high degree of dimensional accuracy in pattern formation. If weight is to be applied to a wax pattern to cause it to conform to the surface of a setter, the shape of the wax pattern may not, in fact, lend itself to applying such weight to the surface of the wax.  
           [0003]    The accuracy of the dimensional shape of an investment casting is dependent on the dimensional accuracy of the pattern from which the casting originates. A pattern which is distorted during cooling outside of its mold will produce a casting which deviates from specified production dimensions. Such deviation may cause the object to be dimensionally unacceptable. There has been a need for a wax pattern that would consistently and economically improve dimensional accuracy in investment cast object.  
         SUMMARY OF THE INVENTION  
         [0004]    Broadly, the present invention is a setter apparatus for engaging patterns or portions thereof during their cooling. The apparatus includes an array of setters each of which has a support body having a support surface, an evacuation chamber and a chamber pressure reducer for causing a heated pattern to be brought into engagement with such support surface. The pressure between the pattern and support surface is reduced below atmosphere pressure causing atmospheric pressure to urge the pattern and surface toward one another. The pattern and support surface are held during cooling until the pattern has reached a temperature such that the pattern is no longer distorted by gravity, temperature differentials or other forces. The invention also includes the method of operating the apparatus.  
           [0005]    The invention is particularly useful for the cooling of patterns used in molding precisely dimensioned objects such as a golf club head. Wood-type golf club heads have convex areas of the club head ball-striking face. These convex curvatures are sometimes referred to as the “roll and bulge”. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is a plan view of a golf club head made in accordance with the present invention;  
         [0007]    [0007]FIG. 2 is a front elevational view of the head of FIG. 1 including the ball-striking surface;  
         [0008]    [0008]FIG. 3 is a plan view of the head showing the face roll;  
         [0009]    [0009]FIG. 4 is a front elevational view of the head showing the face bulge;  
         [0010]    [0010]FIG. 5 is a front elevational view of a pattern used in the practice of the invention;  
         [0011]    [0011]FIG. 6 is an array of pattern setters; and  
         [0012]    [0012]FIG. 7 is a sectional view taken along line  7 - 7  of FIG. 6.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    In FIGS. 1 and 2, golf club head part  10  includes a thin wall  11  and hollow interior  12 . Thin wall  11  includes top wall portion  14 , bottom wall portion  16 , curved face wall portion  17  and rear wall portion  19 . Wall portion  17  has interior surface  17   i  (FIG. 1). Opening  20  receives the sole plate (not shown) which sole plate is a separately fabricated part of the golf club head. Hosel opening  21  receives the club shaft or hosel (not shown).  
         [0014]    The face curvation of wall portion  17  incorporated in a finished golf club  13  is further shown in FIGS. 3 and 4. Curved face wall portion  17  has several characteristics which are horizontal face bulge and vertical face roll. Horizontal face bulge is defined by one or more curved lines L 1  defined by radius R 1 . Curved line L 1  is measured from the heel to the toe in a horizontal plane along face portion  17  (see FIG. 3). Face bulge is usually the same at any point vertically up or down face portion  17 . The other club head face curvature is vertical face roll defined by curved line L 2  inscribed by radius R 2  measured from the top to the bottom of the face in a vertical plane (see FIG. 4). Vertical face roll is usually the same at any point along the face from the heel to the toe. Horizontal face bulge functions to correct or compensate for the effect of the clubhead&#39;s center of gravity which compensates for unwanted hooking or slicing due to off-center hits. Vertical face roll varies the height of the trajectory of the ball depending on the vertical ball-impact location. The reason face roll is part of today&#39;s club design is that it is a tradition in club head face design.  
         [0015]    Pattern  23  is dimensionally similar in size and shape as head portion  10  and is used to create ceramic shell molds for investment casting of metal golf club head part  10 . During mold formation pattern  23  is produced by injection molding of liquid wax pattern material into a mold cavity defined by the shape and size of pattern  23 . Thereafter, the wax pattern material is allowed to solidify within the mold, the segmented mold is opened, and pattern  23  removed from the mold. Pattern  23  has a thin wall  11 ′ including wall portions  14 ′,  16 ′ and  17 ′ similar to golf club head part  10 . Pattern  23 , made preferably of wax, is formed in an injection mold. Because of the size of pattern  23  and the thinness of its wall  11 ′, generally between 0.80″ and 0.150″ and its material and its temperature upon removal from the mold, pattern  23  is unstable at the time of removal. The pattern temperature at removal is in the range of 80° F. and 120° F. Wax patterns having thick sections may, at the time of removal from the mold, have sub-surface temperatures of about 140° F. due to the poor thermal conductivity of wax pattern material.  
         [0016]    With respect to FIGS. 6 and 7, in order to maintain and correct the pattern shape during cooling, patterns are placed against an array  22  of setters  24 . Each setter  24  has a solid and unyielding support wall  25  with a support wall surface  26  substantially the same size of wall portion  17  and of complementary shape to pattern face wall portion  17 ′. Each setter  24  has a chamber  27  with air evacuation passageways  28  connecting wall  25  and chamber  27 . The exterior ends of passage  28  are holes  28   e  and the interior ends are holes  28   e  lying in the setter surface  26 . Chambers  27  function as an evacuation chamber, to cause air to flow through passageways  28 . Evacuation branch conduits  31  serve each chamber  27 . Branch conduits  31  are connected to evacuation line  32  through valves  35 . A vacuum of 5-30 inches of mercury is preferably drawn in supply line  32  and chambers  27  when valves  35  are opened.  
         [0017]    The sizes of holes  28   e  are small relative to the strength of the material of pattern  23 . The hole size is such that pattern  23  is not deformed into passages  28  and therefore no indentation or other marks are formed in pattern  23  during the air evacuation process. Alternatively, setter support walls  25  may be porous allowing air to flow through walls  25  to create the required vacuum. Walls  25  must have sufficient thickness and rigidity to maintain their shape even under the high pressures created by evacuation of chambers  27 .  
         [0018]    The number, spacing, size and shape of passageway exterior holes  28   e  are such that with the pressure reduction urges wall surface  17  against setter surface  26  causing wall surface  17 ′ to assume the correct shape without thereafter any distortion of such surface during cooling. Air is drawn through passageways  28  to create a selectively reduced pressure in chamber  27  and in the space  30  between the face wall portion  17 ′ and support wall  26 . When the pressure is lowered in chamber  27  and in space  30  the surfaces  17 ′ and  26  are brought together. Upon opening of the valve  35  serving a particular setter  24 ,  25  malleable pattern face wall portion  17  is drawn into space  30  thus reducing the volume of space  30  as wall portion  17 ′ conforms to the shape of metal support surface  26 . Atmospheric press (P) exerts a uniform force urging face wall portion  17 ′ against support wall  26 . Since patterns  23  have hollows  12  and openings  20 , walls  17 ′ have an interior surface  17   i ′ (not shown) against which atmospheric pressure operates when a vacuum is drawn.  
         [0019]    Reduced pressure is maintained in chamber  27  until pattern  23  and its face wall  17 ′ have cooled to a state of solidification in which the likelihood of distortion no longer exists.  
         [0020]    Setters may be used to assist in correcting and stabilizing other club head surfaces during cooling; however, it is known that in club head manufacture including woods, irons and putters, that accuracy in fabrication of the profile of the ball-striking face is always of major importance along with other head surfaces.  
         [0021]    Other patterns for molding golf club head parts such as sole plates and crown plates may be processed by this invention. In addition, patterns for manufacturing objects and parts, where improved compliance with specifications of surface profiles is desired, may be treated using the present invention, such as, for example, aircraft air foil blades and vanes.  
         [0022]    In an alternative embodiment, setters  24  are cooled below ambient temperature prior to receiving the malleable patterns. Cooled setters  24  accelerate pattern cooling time. This invention contemplates the cooling of patterns to a state of solidification for storage or other reason in which state the use of setters is not effective and thereafter raising the pattern temperature to a level where setter treatment is useful.  
         [0023]    In the operation of the method of the present invention, pattern  23  having a high temperature is removed from its mold and transported to a setter  24  which is normally at room temperature. During such transport, pattern  23  is malleable and subject to change in shape, size and other distortions. Pattern  23  with its surface  17 ′ is placed against setter surface  26  leaving a very small space  30  between the surfaces. Since setter  24  and its surface  26  are at room temperature, pattern  23  is caused to cool when it is placed on setter  24 .  
         [0024]    The reduction of pressure in space  30 , passages  28  and setter chamber  27  causes surfaces  17 ′ and  26  to come together reducing or eliminating space  30 . When such surfaces are brought together (and thereafter continued to be urged together during cooling), pattern surface  17 ′ is reconfigured to the extent it was distorted during the removal from its mold and its transport to the setter. To the extent no distortion of pattern  23  or its surface  17 ′ or portions thereafter has occurred prior to setter engagement, setter  24  functions to maintain the shape and size of pattern surface  17 ′.