Patent ID: 8579559
Filing Date: 2013-11-12
Classification: B23C,Y10T

Abstract:
1. A grooving work method for forming a groove having a cross section of a Christmas tree shape for fixing blade legs of a turbine to an outer circumference of a turbine shaft by fitting a female groove and a male member together, wherein the female groove has a cross section symmetrical with respect to a center line of the groove extending in a groove depth direction from a groove opening portion to a groove bottom portion, and the female groove has two or more larger-width portions each extending from the centerline to a location spaced from the centerline at both sides of the groove in a groove width direction perpendicular to the groove depth direction, and the female groove has one or more constricted portions constricted in the groove width direction and disposed one by one between, in the groove depth direction, adjacent larger-width portions, the larger-width portions and the one or more constricted portions being configured such that the nearer they are to the groove opening portion in the groove depth direction, the larger the width in the groove width direction; the grooving work method comprises: at least a first cutting step of performing cutting by using a first cutting tool having a first cutting blade by gradually moving the first cutting blade in a direction perpendicular to an axis parallel to the center line of the groove while rotating the first cutting blade about the axis that is parallel to the center line in order to form each one of the two or more larger-width portions one by one; and a second cutting step of performing cutting by using a second cutting tool different from the first cutting tool.