Method and casting core for forming a landing for welding a baffle inserted in an airfoil
A method and casting core for forming a landing for welding a baffle inserted into an airfoil are disclosed, wherein the baffle landing of the blade or vane is formed in investment casting by the casting core rather than by wax, reducing tolerances and variability in the location of the baffle inserted into the cooling cavity of airfoil when the baffle is welded to the baffle landing.
1. A method of forming a first landing and a second landing for welding a first baffle and a second baffle inserted into a cooling cavity of an airfoil comprising the steps of:
forming a casting core having a first portion in the shape of the first landing, the first portion located at one of an outer platform end or an inner platform end disposed at opposing longitudinal ends of the casting core;
forming the second portion of the casting core in the shape of the second landing, the second portion located at the other of the outer platform end or the inner platform end;
overmolding the casting core with wax to form a casting pattern having a first portion in the shape of the first landing and a second portion in the shape of the second landing;
shelling the casting pattern with a shell;
removing the casting pattern to form a void between the shell and the casting core;
pouring metal into the void to surround the casting core; and removing the shell, wherein the first landing is formed by the first portion of the casting core in the shape of the first landing and the second landing is formed by the second portion of the casting core in the shape of the second landing;
wherein the first portion includes a laterally-extending first step portion being configured to mold the first landing as a spanwise-facing surface of the airfoil relative to an airfoil span direction onto which the first baffle is welded providing a spanwise locating surface for the first baffle;
wherein the cooling cavity portion extends longitudinally between the outer platform end and the inner platform end; and
wherein the first step portion extends substantially perpendicularly laterally from the cooling cavity portion.
2. The method of claim 1 , wherein the step of forming a casting core having a first portion in the shape of the first landing is performed by injection molding.
3. The method of claim 1 , wherein the casting core is a ceramic polymer.
4. The method of claim 1 , wherein the casting core is a refractory metal core.
5. The method of claim 1 , wherein the step of shelling the casting pattern with a shell is performed using a ceramic slurry.
6. The method of claim 1 , wherein the tolerance of the surface profile of the first landing is not greater than 0.004 in. (0.1016 mm).
7. A method of forming a first landing for welding a first baffle inserted into a cooling cavity of an airfoil and a second landing for welding a second baffle inserted into the cooling cavity comprising the steps of:
forming a casting core having a first portion in the shape of the first landing and a second portion in the shape of the second landing;
overmolding the casting core with wax to form a casting pattern having a first portion in the shape of the first landing and a second portion in the shape of the second landing;
shelling the casting pattern with a shell;
removing the casting pattern to form a void between the shell and the casting core;
pouring metal into the void to surround the casting core; and removing the shell, wherein the first landing is formed by the first portion of the casting core in the shape of the first landing and the second landing is formed by the second portion of the casting core in the shape of the second landing;
wherein the first portion is located at one of an outer platform end or an inner platform end disposed at opposing longitudinal ends of the casting core and the second portion is located at the other of the outer platform end or the inner platform end;
wherein the first portion includes a laterally-extending first step portion being configured to mold the first landing as a spanwise-facing surface of the airfoil relative to an airfoil span direction onto which the first baffle is welded providing a spanwise locating surface for the first baffle;
wherein the cooling cavity portion extends longitudinally between the outer platform end and the inner platform end; and
wherein the first step portion extends substantially perpendicularly laterally from the cooling cavity portion.
8. The method of claim 7 , wherein the step of forming a casting core having a first portion in the shape of the first landing and a second portion in the shape of the second landing is performed by injection molding.
9. The method of claim 7 , wherein the casting core is a ceramic polymer.
10. The method of claim 7 , wherein the casting core is a refractory metal core.
11. The method of claim 7 , wherein the step of shelling the casting pattern with a shell is performed using a ceramic slurry.
12. The method of claim 7 , wherein the tolerance of the surface profile of the first landing and second landing is not greater than 0.004 in. (0.1016 mm).