Inflator bag for vehicle occupant restraining apparatus and method for manufacturing the same

A method for manufacturing an inflator bag for a vehicle occupant restraining apparatus which is able to expand and develop by being filled with a high-pressure gas and is capable of restraining a vehicle occupant by being expanded and developed, said method comprising:

• forming a tube-shaped body having an approximately rectangular cross-section in which each of longitudinal sides is smaller than each of horizontal sides by deforming a cross section of a pipe cut so as to have a specified length;
• forming a folded line along which each of side face plates serving as each of said longitudinal sides of said tube-shaped body is folded in a manner to form a valley line toward an inside portion of said tube-shaped body in an intermediate portion in its height direction;
• forming a folded line along which each of end face plates is folded in a manner to form a valley line toward an inside portion of said tube-shaped body in an intermediate portion in its height direction, which is used when opening faces on both sides of said tube-body are blocked with said end face plates;
• forming a box-shaped main body by blocking said opening faces on both sides of said tube-shaped body with said end face plates and by using side face plates serving as longitudinal sides of said tube-shaped body and said end face plates as gore portions;
• forming an overlaid and folded portion at an end of each of said gore portions in a manner that each corner of the tube-shaped body is sandwiched between one of the longitudinal sides and one of the horizontal sides and the overlaid and folded portion at each of said gore portions is folded over at a same time;
• and
• obtaining an inflator bag folded so as to be in a flat state by folding, in a manner to form a valley line, each of said gore portions made up of said side face plates and end face plates along said folded line.