CONCENTRICITY RING

摘要

The invention provides a method of assembling a gas turbine engine using a concentricity ring (1) to compensate for assembly tolerances. The blade tips (8) of the gas turbine during turbine rotation define a tip surface of rotation concentric (3) the shaft axis (5). Due to cumulative tolerances in part manufacture and assembly, the shaft axis is invariably radially eccentr ic the engine axis at the axial position of the turbine an assembly eccentricit y within the range between zero and a predetermined allowable assembly tolerance. The invention relates to the step of positioning a concentricity ring (1) with: an outer cylindrical surface (18) engaging the internal cylindrical surface of the engine housing; and an inner cylindrical surface (19) engaging the external cylindrical surface of the turbine shroud, the outer and inner cylindrical surfaces of the concentricity ring (1) being eccentric a ring eccentricity within the range between zero and said predetermined allowable assembly tolerance to rectify the assembly eccentricity of the moving and static components in a simple expeditious manner.