Apparatus and method for reducing operating stress in a turbine blade and the like
A core for casting a metal part having a body with solid portions spaced apart by hollow portions. The body includes at least one support element extending between adjacent solid portions. The support element provides stiffness and strength for the casting core during the casting process. The support element has an optimized shape to prevent the core from fracturing during the casting process and to minimize operating stress in the metal part around the area formed by the support element.
1. A method for manufacturing a core for casting a metal part comprising the steps of:
providing ceramic slurry;
injecting the slurry into a core die to form a green core with solid portions spaced apart by a corresponding hollow portion; and
forming at least one support element between adjacent solid core portions, the at least one support element having a shape optimized to prevent the core from fracturing during a casting process and to minimize operating mechanical stress in the area of the metal part formed by the support element, said shape of said at least one support element including a cross-sectional shape having a thickness at a central location that is greater than a thickness at either side of said cross-sectional shape.
2. The method of claim 1 , further comprising the steps of:
removing the core from the die;
drying the core; and
heating the core at a predetermined temperature to increase material strength.
3. The method of claim 1 further comprising the steps of:
treating the surface of the core to increase strength of the core; and
machining the core to meet specification dimensions.
4. The method of claim 1 , wherein a cross section of the at least one support element formed comprising the steps of:
defining a first radius;
defining a second radius a first distance from the first radius;
defining a third radius a second distance from the second radius;
defining a fourth radius having a circumference positioned tangent to the circumference of the first, second, and third radii; and
defining a fifth radius having the circumference positioned tangent to the circumference of the first, second, and third radii, and with said first, second, third, fourth and fifth radii being utilized to form said shape of said at least one support element, with said second radii at least partially forming said central location, and said first and third radii being utilized to form said sides of said cross-sectional shape.
5. The method of claim 4 , wherein the first and third radii are substantially equal in length.
6. The method of claim 4 , wherein the fourth and fifth radii are substantially equal in length.
7. The method of claim 4 , wherein the first and second distances are substantially equal in length.
8. The method of claim 4 , wherein the fourth and fifth radii are positioned on opposite sides of the support cross-section.
9. The method of claim 4 , wherein said thickness at said central location is defined by said second radius, and said thicknesses at said sides are defined by said first and third radii.
10. The method of claim 1 , wherein said at least one support element is formed to be integral with said adjacent solid core portions.