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A method for Investment Castings
One aspect of the invention involves a method for forming an investment casting pattern. A first core is installed to a first element of a molding die to leave a first portion of the first core protruding from the first element. After the installing, the first element is assembled with a feed core and a second element Cnc Screw of the molding die so that the first portion contacts the feed core and is flexed. A material is molded at least partially over the first core and feed core.
In various implementations, the assembling may include causing engagement between the first core and feed core to at least partially maintain an orientation of the feed core relative to the molding die. A second core may be installed to the second element to leave a first portion of the second core protruding from the second element. A second core may be installed to the first element to leave a first portion of the second core protruding from the first element. The first core may have a spine and a number of tines extending from the spine. The first core may comprise, in major weight part, one or more refractory metals. The feed core may comprise, in major weight part, one or more ceramic materials and/or refractory metals. The material may comprise, in major weight part, one or more waxes.
Another aspect of the invention involves a method for forming an investment casting mold. An investment casting pattern may be formed as described above. One or more coating layers may be applied to the pattern. The material may be substantially removed to leave the first core and feed core within a shell formed by the coating layers. The method may be used to fabricate a gas turbine engine airfoil element mold.
Another aspect of the invention involves a method for investment casting. An investment casting mold is formed as described above. Molten metal is introduced to the investment casting mold. The molten metal is permitted to solidify. The investment casting mold is destructively removed. The method may be used to fabricate a gas turbine engine component.
Another aspect of the invention involves a component for forming an Investment Castings pattern. The component includes a spine and a number of tines extending from the spine.
In various implementations, the spine and tines may be unitarily formed and may consist essentially of a refractory metal-based material, optionally coated. The tines may be tapered over a first region from a relatively wide cross-section proximal root at least to a relatively small cross-section intermediate location. The tines may be less tapered over a second region, distally of the first region. The spine may have integrally-formed spring elements. There may be at least six such tines. The spine may provide at least 90% of a mass of the component. The tines may be at least five mm in length. The spine may define a direction of insertion for inserting the spine into a die. The tines may extend off-parallel to the direction of insertion.
