Keywords: forging, coordinate measurement, dimensional accuracy, finite element, aerofoil blades.

The manufacturing criteria applied to the hot forging of aerofoil blades demands that the component is manufactured to within a specified dimensional tolerance. Forging of high temperature alloys creates distortion along the aerofoil cross sections, as well as disparities in aerofoil thickness due to die deflection [1]. However, due to the complexity of the forging process and the sensitivity of the process conditions, forging process design is very much dependent on manufacturing trials [2]. By employing finite element analysis, which can accurately simulate the forging process, it is possible to quantify the forging error and optimise the die shape in order to minimise the error and ensure the blade dimensions are within tolerance. Therefore, by using an integrated forging simulation and optimisation approach it will be possible to significantly improve the overall efficiency of forging production. The industrial partners of this project employ the coordinate measurement process to evaluate the dimensional accuracy of their turbine blades. At the end of each forging trial, this technique is used to quantify the forging error at specific sections along the aerofoil and the dies are modified accordingly.

In order to provide the necessary comparison between the simulated optimisation process and that employed in industry and to ensure that the CAD model of the die may be compensated correctly, it's necessary to evaluate the forging error generated in simulation using a similar method to that employed by the coordinate measurement process. To this end, the long term aim of this study is to develop a system to quantify the forging error in an FE simulation for each respective aerofoil cross section using the same procedure as that implemented by the coordinate measurement process in order to assess the accuracy of the FE results.

Forging simulations were conducted using Abaqus^TM and Deform^TM finite element packages. To date, an automated blade positioning algorithm has been successfully implemented using a method which is similar to that employed by the coordinate measurement process. Also, software has been successfully developed to accurately generate blade and nominal profiles for error quantification. After establishing a measurement data positioning procedure it will be possible to quantify the FE forging error and thereby provide an accurate comparison with forging error data from actual aerofoil sections.

1

Ou H., Armstrong C.G., Price M.A., "Die shape optimisation in forging of aerofoil sections", Journal of Materials Processing Technology, 132(1-3): 21-27, 2003. doi:10.1016/S0924-0136(02)00204-2

2

Ou H., Lan J., Armstrong C.G., Price M.A., Walloe S.J., Ward M.J., "Reduction in post forging errors for aerofoil forging using finite element simulation and optimisation", Modelling Simul Mater, 14: 179, 2006. doi:10.1088/0965-0393/14/2/004

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £75 +P&P)