Patent ID: 7247217

Claim:
A method for constructing a helmet comprising the steps of: (a) press-forming an interior shell and an exterior shell from general engineering plastics; (b) applying conventional adhesive to the inside surface of the exterior shell to fasten the interior and exterior shells together to form an integral shell unit; (c) placing said shell unit inside a plastic or rubber film bag and sealing the whole of the film bag tightly with only an opening left for a vacuum tubing connected to a vacuum means; (d) turning on said vacuum means and vacuuming clear of any air pockets in the space between the two shell; (e) submerging the vacuumed film bag containing the shells unit under fluid contained in an airtight and pressure-resistant vessel; (f) applying pressure at between 0.01-1 Mpa to said vessel and maintaining fluid temperature at between 10° C.-99° C. for 2-60 seconds to further pressurize the fastening process of the interior and exterior shells; and (g) releasing the inside pressure of said vessel and turning off the vacuum applied to said sealed vacuumed film bag containing the shell unit and taking the shell unit out of the fluid and retrieving the shell unit from the film bag.