Completely folded body of airbag and folding method of the same

A folding method of a completely folded body of an airbag which is stored in a boss portion of a steering wheel and is completely inflated to be supported by an upper surface of a ring portion of the steering wheel steered by a driver,

• the airbag being formed by coupling outer circumferential peripheries of a driver-side wall and a vehicle-side wall supported by the ring portion which have substantially circular shape to each other,
• the vehicle-side wall being provided, in a center, with an inflow opening which is open to admit an inflation gas to flow inside, and a mounting portion which is disposed in a circumferential periphery of the inflow opening and is used to mount the airbag in the boss portion,
• the completely folded body being configured such that a front-side folded portion and a rear-side folded portion are disposed on front and rear sides of an upper side of the mounting portion,
• the front-side folded portion and the rear-side folded portion being formed respectively from a front overlapped portion and a rear overlapped portion which are centered on the mounting portion in a state where the driver-side wall and the vehicle-side wall are overlapped to be flatly deployed,
• at least the front-side folded portion of the front-side folded portion and the rear-side folded portion having such a folded shape that a tip separated longitudinally from the mounting portion of the front overlapped portion is stored in a dent portion, in which a front side is open and a rear side is dented, between a mounting-portion-side folded portion near the mounting portion and a central folded portion between the tip and the mounting-portion-side folded portion,
• the tip of the front overlapped portion including a leading edge separated longitudinally, farthest from the mounting portion, and a tip root-side portion connected to the leading edge,
• the leading edge being provided on an upper side of the tip root-side portion in the front-side folded portion to be inverted rearward to a central side of the mounting portion,
• the central folded portion in the front-side folded portion being connected to the tip root-side portion, and includes an upper-side contact portion which contacts with the leading edge at an upper side of the tip and is formed from the front overlapped portion,
• the method comprising:
• nipping both sides of the upper-side contact portion when the mounting-portion-side folded portion, the central folded portion, and the tip are folded from a state of being flatly deployed from the mounting portion in the front-side folded portion;
• rotating a front periphery of the nipped upper-side contact portion to a vehicle-side wall side to be vertically inverted, and disposing the nipped upper-side contact portion on the front side of the upper side of the mounting portion;
• and then
• folding the leading edge by attaching a crease between the leading edge and the tip root-side portion and inserting the leading edge to a lower position of the upper-side contact portion.