Patent ID: 7112249

Claim:
A method of controlling application of a pressurized working gas against one side of a sheet material workpiece to stretch it into conformance with a heated forming surface as a succession of said workpieces are stretched into conformance with said forming surface, said method comprising: predetermining working gas pressure relationships for stretch forming strain rates over a range of temperatures for said forming of said sheet material workpieces into a desired product shape; predetermining a forming time-gas pressure application reference schedule at a reference forming temperature for said forming of said product shape; and during the forming of said sheet material workpieces; continually measuring the temperature at a location selected for controlling the application of gas pressure for forming said sheet material workpieces; and adjusting the pressure of the working gas applied against said workpiece using a said pro-determined working gas pressure relationship for the measured temperature when said measured temperature differs from said reference forming temperature.