Method for reconditioning blades

Method for reconditioning axial-construction blades for stages of turbo-machinery that have a material deficiency resulting from wear and tear, damage, or dimensions that are smaller than specified, in which the protective coating or blade material is removed over at least part of the blade, and is replaced with new blade material or a new protective coating, comprising:

• a) determining an actual geometry of the blade via measuring techniques at defined points, and storing the actual geometry in a data processing system,
• b) defining a desired geometry of the blade approximately by an axial desired profile or desired cross-section, in a desired position, and storing the desired geometry in the data processing system,
• c) comparing the desired geometry basically along axial cutting planes with the actual geometry that has been measured at certain specific points wherein in a case of significant deviations a local desired profile is overlaid, via rotation or shifting, over a local actual profile, which has been measured at the certain specific points,
• calculating an adjusted desired geometry for a radial height of the blade, which is free from buckled and stepped areas, from the desired profiles that deviate from the desired positions, and from the desired profiles that may be left in the desired positions;
• storing the adjusted desired geometry,
• d) mathematically reducing the adjusted desired geometry by a defined amount of coating to be removed, until a net geometry that lies, to a greatest extent possible, or completely, within the blade material, is reached,
• e) producing the calculated net geometry over at least a partial area of the blade via removal of material, while generating defined, rounded crossover points to areas of the blade from which no material is to be removed, and
• f) applying the new blade material or the new protective coating to the finished net geometry, in a thickness that is equal to a thickness of the amount of coating that was removed, which was calculated from the adjusted desired geometry, at least to the greatest extent possible.