Forming metal plate

Abstract

A metal forming method comprising the steps of heating of metal plate to a temperature below the temperature at which grain boundary melting occurs, placing the plate on a bottom refractory-compound die of temperature lower than plate temperature, lowering a top refractory-compound die of temperature lower than plate temperature onto the plate, the temperature of the plate when the top die first contacts it in the step of lowering being at least high enough to maintain springback at less than 1/8-inch in 25-feet if the plate were allowed after being formed to cool naturally between the dies to 125.degree.F, the top die having sufficient weight such that the plate is deformed to conform to the dies in the step of lowering, the weight of the top die bearing on the plate, after it has conformed to the dies, with a pressure up to 100 pounds per square inch, leaving the plate between the dies until the plate time and temperature history following the lowering of the top die is such that a springback of less than 1/8-inch in 25-feet is experienced on opening the dies, and then opening the dies for removal of the plate.

Dependencies are inferred from the claim text.