Patent ID: 6577919
Filing Date: 2003-06-10
Classification: B21D

Abstract:
A method for blow molding a superplastic metal plate by in relation to time applying thereto pneumatic pressure that is based on a maximum value of a strain rate of the superplastic metal plate as a set pattern of pneumatic pressure in relation to time when the metal plate is subjected to a high-speed molding where the strain rate is more than 10âˆ’2(1/s), after being heated to a desired temperature, comprising the steps of:entering data in a storage means on a shape into which a metal sheet is to be blow molded and on properties of a material of the metal sheet to store the data in the storage means; determining a set pattern of a pneumatic pressure in relation to time from the entered data on the shape and the properties of the metal sheet; dividing the set pattern of the pneumatic pressure into an appropriate number of parts in relation to time, wherein a first part divided from the set pattern of the pneumatic pressure is a first pattern area in which the pneumatic pressure varies relatively steeply, and wherein the remaining part divided from the set pattern of the pneumatic pressure is a second pattern area, following the first pattern area, in which the pneumatic pressure varies gradually compared with the first pattern area; determining values of parameters for controlling the pneumatic pressure for each part divided from the set pattern of the pneumatic pressure, wherein the values of the parameters are determined by changing the values of the parameters of a proportional plus integral plus derivative control for the parts divided from the pattern of the pneumatic pressure; and controlling the pattern of the pneumatic pressure using the determined values of the parameters.