Abstract: A method of producing a lid including a top plate and a side wall extending downward from a periphery of the top plate, using molds, the molds including a papermaking mold and a drying mold. The top plate is provided with an abutting part abutting against an edge of an opening of a container, while an undercut part to be fitted to a lower part of the edge is formed on the side wall so as to be located below the abutting part. The papermaking mold is provided with suction holes at a level corresponding to a level of the undercut part formed on an inner surface of the side wall. The side wall is suctioned using the suction holes when a molded article is at least in one of several states to form the undercut part in a convex shape on the inner surface of the side wall.

Abstract: A method of forming an undercut which is engageable with an edge, on a side wall of a cover intermediate body using a cover intermediate body and a secondary processing die. In the secondary processing die, a moving inner core has, on the outer surface thereof, a concave shape corresponding to a convex shape of the inner surface of the undercut. The moving inner core is made up of a plurality of core segments which are arranged along the circumferential direction. Each core segment is vertically movable along an inclined surface of a core. When the moving inner core is moved upward, the moving inner core transforms smaller than the inner diameter of the side wall of a cover. The slide core has, on the inner surface thereof, a convex shape corresponding to the concave shape of the undercut.

Abstract: A method of forming an undercut which is engageable with an edge, on a side wall of a cover intermediate body using a cover intermediate body and a secondary processing die. In the secondary processing die, a moving inner core has, on the outer surface thereof, a concave shape corresponding to a convex shape of the inner surface of the undercut. The moving inner core is made up of a plurality of core segments which are arranged along the circumferential direction. Each core segment is vertically movable along an inclined surface of a core. When the moving inner core is moved upward, the moving inner core transforms smaller than the inner diameter of the side wall of a cover. The slide core has, on the inner surface thereof, a convex shape corresponding to the concave shape of the undercut.

Abstract: A method of producing a lid including a top plate and a side wall extending downward from a periphery of the top plate, using molds, the molds including a papermaking mold and a drying mold. The top plate is provided with an abutting part abutting against an edge of an opening of a container, while an undercut part to be fitted to a lower part of the edge is formed on the side wall so as to be located below the abutting part. The papermaking mold is provided with suction holes at a level corresponding to a level of the undercut part formed on an inner surface of the side wall. The side wall is suctioned using the suction holes when a molded article is at least in one of several states to form the undercut part in a convex shape on the inner surface of the side wall.

Abstract: A method of forming an undercut which is engageable with an edge, on a side wall of a cover intermediate body using a cover intermediate body and a secondary processing die. In the secondary processing die, a moving inner core has, on the outer surface thereof, a concave shape corresponding to a convex shape of the inner surface of the undercut. The moving inner core is made up of a plurality of core segments which are arranged along the circumferential direction. Each core segment is vertically movable along an inclined surface of a core. When the moving inner core is moved upward, the moving inner core transforms smaller than the inner diameter of the side wall of a cover. The slide core has, on the inner surface thereof, a convex shape corresponding to the concave shape of the undercut.