Patent ID: 6907761
Filing Date: 2005-06-21
Classification: B21D,Y10T

Abstract:
1. A method of superplastically forming a workpiece comprising placing the workpiece having a thickness and a surface in a die having a shape, heating the whole of the workpiece up to a temperature at which the workpiece is superplastically formable, applying a pressure differential across the workpiece to superplastically form the workpiece to the shape of the die and heating and/or cooling the workpiece to provide a temperature distribution across the workpiece during the superplastic forming process to control the thickness of the workpiece, the method further comprising measuring the temperature of the workpiece and producing a temperature signal, analysing the temperature signal to determine the measured temperature distribution of the workpiece at at least one stage in the superplastic forming process, maintaining a database of desired temperature distributions of the workpiece at different stages in the superplastic forming process, comparing the measured temperature distribution of the workpiece at the at least one stage in the superplastic forming process with the desired temperature distribution of the workpiece at the said stage in the superplastic forming process and controlling the heating and/or the cooling such that the temperature distribution of the workpiece is maintained at the desired temperature distribution of the workpiece or such that the temperature distribution of the workpiece is adjusted to more closely match the desired temperature distribution of the workpiece to control the thickness of the workpiece.