Valve plates for container valves and method of manufacturing same

摘要

A valve plate is manufactured by stamping round two-ply blanks out of two superimposed strips of material and shaping the valve plate out of the blanks while retaining the double ply. The plate is provided with a dome by this process. The outer ply is now provided with threading in the vicinity of the dome. If the plate is damaged when an adaptor is subsequently screwed onto it, the damage will be confined to the outer layer.