Method for drilling cooling holes in turbine blades

Abstract

Standard STEM drilling equipment is utilized to effect the electrochemical removal of material in multiple directions in order to produce cooling holes with turbulator ridges. An initial section of the cooling hole is drilled by displacing the electrode vertically into the turbine blade under conditions that produce a hole with an approximate clearance of 0.3 mm around the electrode. The electrode is then moved horizontally about 0.15 mm toward one side of the wall of the hole, thus leaving a clearance of about 0.45 mm on the other side. Vertical drilling of a second hole section is then resumed by the conventional electrochemical process. Because of the position of the electrode relative to the wall of the hole and the correspondingly different current densities in place along the circumference of the wall, a vertical inset is formed below the initial hole section, which creates a turbulator ridge. The process can be repeated in different directions to produce a hole with a common core and a plurality of insets drilled in different directions and having different lengths for each section, as desired. Thus, cooling holes with turbulators disposed in a variety of different configurations can be manufactured with standard equipment.

Dependencies are inferred from the claim text.