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Proceedings Paper

Turbine blade fixture design using kinematic methods and genetic algorithms
Author(s): John J. Bausch III
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Paper Abstract

The design of fixtures for turbine blades is a difficult problem even for experience toolmakers. Turbine blades are characterized by complex 3D surfaces, high performance materials that are difficult to manufacture, close tolerance finish requirements, and high precision machining accuracy. Tool designers typically rely on modified designs based on experience, but have no analytical tools to guide or even evaluate their designs. This paper examines the application of kinematic algorithms to the design of six-point-nest, seventh-point-clamp datum transfer fixtures for turbine blade production. The kinematic algorithms, based on screw coordinate theory, are computationally intensive. When used in a blind search mode the time required to generate an actual design is unreasonable. In order to reduce the computation time, the kinematic methods are combined with genetic algorithms and a set of heuristic design rules to guide the search. The kinematic, genetic, and heuristic methods were integrated within a fixture design module as part of the Unigraphics CAD system used by Pratt and Whitney. The kinematic design module was used to generate a datum transfer fixture design for a standard production turbine blade. This design was then used to construct an actual fixture, and compared to the existing production fixture for the same part. The positional accuracy of both designs was compared using a coordinate measurement machine (CMM). Based on the CMM data, the observed variation of kinematic design was over two orders-of-magnitude less than for the production design resulting in greatly improved accuracy.

Paper Details

Date Published: 13 October 2000
PDF: 12 pages
Proc. SPIE 4192, Intelligent Systems in Design and Manufacturing III, (13 October 2000); doi: 10.1117/12.403683
Show Author Affiliations
John J. Bausch III, Rochester Institute of Technology (United States)

Published in SPIE Proceedings Vol. 4192:
Intelligent Systems in Design and Manufacturing III
Bhaskaran Gopalakrishnan; Angappa Gunasekaran, Editor(s)

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