Synthetic resin preform and sprue assembly and method of making same

In a method of making an investment mold, the steps comprising:

• a. mounting on a crucible former an elongated sprue tree having a plurality of conduit formers each having a free end portion of circular cross section and spaced along the length and about the periphery of said spruce tree;
• b. mounting on the conduit formers of said sprue tree a plurality of sprue elements each having a gate portion spaced from one of said conduit formers and a reservoir portion therebetween, said reservoir portion having a circular cross section recess formed therein non-coaxially relative to its gate portion whereby said reservoir and gate portions are mounted for rotation about their respective conduit formers;
• c. mounting a pattern on the free end of said gate portions;
• and
• d. orienting the patterns by adjusting the angular orientations of said gate portions by rotating said reservoirs about their respective conduit formers.

A synthetic resin preform and sprue assembly comprising a base for engagement with a crucible former, said base having a plurality of seating recesses formed therein, a plurality of sprue formers spaced from said base, and conduit forming means extending between said base and said sprue formers, said conduit forming means and said sprue formers are elongated members formed with said sprue formers extending at an angle to its corresponding conduit forming means, said conduit forming means each having an end portion seated in one of said recesses, said recesses and said end portions having circular cross sections and being relatively sized so that said end portions are coaxially aligned with said recesses, whereby said elongated members are rotatably mounted in said recesses, said sprue formers each comprising a first portion connected to and extending outwardly from said conduit forming means, a gate portion spaced therefrom, and a reservoir portion therebetween, said reservoir portion having an enlarged cross section relative to that of said first and gate portions, and said gate portion being adapted for supporting a pattern thereon whereby a pattern may be disposed on the free end of a gate portion of each of the sprue formers and the patterns may be oriented by adjustment of the angular orientation of said elongated members by rotation of said members relative to said base about said end portions, and a plurality of sprues in communication with a crucible portion may be formed in an investment by firing a ceramic composition containing the preform and sprue assembly.

A synthetic resin preform and sprue assembly comprising a base for engagement with a crucible former, a plurality of sprue formers spaced from said base, and conduit forming means extending between said base and said sprue formers, said sprue formers each comprising a first portion connected to and extending outwardly from said conduit forming means and terminating in a free end portion, a gate portion spaced therefrom, and a reservoir portion therebetween, said reservoir portions having an enlarged cross section relative to that of said first and gate portions and further having a recess formed therein with the free end portion of one of said sprue member first portions being seated in each of said recesses whereby said reservoir portions are rotatably mounted on said free end portions of said sprue member first portions with each of said gate portions extending at an angle to the longitudinal axis of its corresponding sprue member first portion whereby rotation of said reservoir portions provides a desired position and orientation of said gate portions, and said gate portions being adapted for supporting a pattern thereon whereby a pattern may be disposed on the free end of a gate portion of the sprue formers and a plurality of sprues in communication with a crucible portion may be formed in an investment by firing a ceramic composition containing the preform and sprue assembly.

In a mold forming assembly, the combination comprising:

• a. a crucible former having a generally dome-shaped portion with an upwardly opening coaxial recess therein;
• and
• b. a synthetic resin preform and sprue assembly seated in said recess of said crucible former, said synthetic resin preform and sprue assembly comprising a base having a peripheral configuration conforming to said recess and seated snugly therein, said base having a plurality of upwardly opening circular cross section seating recesses formed therein, a plurality of sprue formers spaced from said base, and conduit forming means extending between said base and said sprue formers, said conduit forming means having end portions of circular cross section adapted to be seated within said seating recesses, and said circular cross section end portions and said seating recesses being respectively sized so that said end portions are coaxially aligned with said seating recesses for rotation therein, said sprue formers each comprising a first portion connected to and extending outwardly from said conduit forming means at an angle relative thereto, a gate portion spaced therefrom, and a reservoir portion therebetween, said reservoir portion having an enlarged cross section relative to that of said first and gate portions, and said gate portions being adapted for supporting a pattern thereon whereby a pattern may be disposed on the free end of a gate portion of the sprue formers and the pattern may be oriented by adjustment of the angular orientation of the conduit forming means by rotation thereof in said seating recesses about said end portions, and a plurality of sprues in communication with a crucible portion may be formed in an investment by firing a ceramic composition containing the preform and sprue assembly.