Control of Fir-Tree Roots of Gas Turbine Blades.

A multidimensional indicator system is described which simultaneously controls all the elements of the fir-tree root of a turbine blade. The system allows the concurrent measurement of deviation in each measured point, the mutual axial displacement of root sides in any two symmetrical points, the longitudinal deviation of any profile section, the transverse deviation of the whole profile, and other deviations of the blade root. The measurements, accuracy amounts to 0. 002 mm and allows the fabrication of blade roots with an accuracy of 0. 02 to 0. 03 mm.