Patent ID: 9296053
Filing Date: 2016-03-29
CPC Classification: B23C,B24B,B24D,F01D,F05D,Y10T

Claim Text:
1. A tool for use in the formation of a firtree slot in a disc of a bladed disc assembly in a turbine engine, the firtree slot having two opposed sides defining a profile of the firtree slot, the tool comprising: a tip portion rotatable about an axis of rotation and having lateral side surfaces with a shape matching the profile of sides of the firtree slot to be formed, the tool being smaller than the profile of the formed firtree slot so that the tool will only engage one of said sides of the firtree slot at a time, the tip portion having an axial distal finishing surface transverse to the axis of rotation which extends centrally therethrough, the axial distal finishing surface including an annular frusto-conical surface portion surrounding a recessed portion centrally disposed within the axial distal finishing surface, the annular frusto-conical surface removing excess ridges formed in the bottom of the firtree slot, an entirely of the axial distal finishing surface remaining within the firtree slot during rotating about the axis of rotation, the axial distal finishing surface in operation contacting a bottom of the firtree slot, the recessed portion of the axial distal finishing surface being spaced apart from the bottom of the firtree slot during rotation of the tool while the axial distal finishing surface is in contact with the bottom of the firtree slot, in order to avoid a zero speed contact point between the tool and the disc during rotating operation of the tool.