Cup bottom incurl workstation for a cup making machine

A paperboard cup bottom incurl workstation useful in combination with a cup making machine having a rotating turret with a plurality of mandrels, each mandrel being coordinated to become a registered mandrel as it moves into a position proximate the bottom incurl station, the registered mandrel being configured to receive a bottom blank having an outer lip and a sidewall blank including a flap that is curled inwardly over the outer lip to create a recessed area in the bottom of the cup, the bottom incurl workstation comprising:

• a central flap guide having a peripheral surface;
• and
• a rotatable roller assembly having an array of rollers disposed to contact a bottom edge of the flap, each roller having an arcuate surface extending into cooperation with the peripheral surface, wherein as the registered mandrel moves closer to the array of rollers and the flap guide, the bottom edge of the flap is directed inwardly along the arcuate surfaces of the rollers to the peripheral surface which is configured to guide the flap into the recessed area;
• further wherein the central flap guide is fixed with respect to rotation, and the rollers are rotatable;
• the paperboard cup bottom incurl station further comprising:
• a movable carriage assembly, wherein the central flap guide and the rotatable roller assembly are mounted to the movable carriage assembly and the carriage assembly is connected to a cam assembly configured to reciprocate the carriage assembly;
• and
• a spring release mechanism that allows a portion of the carriage assembly to move when sufficient force is applied longitudinally against the central flap guide.

A container bottom incurl workstation useful in combination with a container making machine having a rotating turret with a plurality of mandrels, each mandrel being coordinated to become a registered mandrel as it moves into a position proximate the bottom incurl station, the registered mandrel being configured to receive a bottom blank having an outer lip and a sidewall blank including a flap that is curled inwardly over the outer lip to create a recessed area in the bottom of the container, the bottom incurl workstation comprising:

• a framework;
• a carriage assembly movably mounted on the framework;
• a roller assembly rotatably mounted in the carriage assembly for rotation about a roller assembly axis, the roller assembly including a support plate and at least two rollers mounted to the support plate at a position radially outward from the roller assembly axis, wherein each roller includes a surface for guiding the bottom edge of the flap as the roller assembly and registered mandrel are moved towards one another;
• and
• a central flap guide including a peripheral surface that cooperates with the roller surfaces to curl the flap back into the recessed area, the central flap guide being fixed with respect to rotation about the roller assembly axis.

A method for forming the bottom of a container having a bottom blank and a sidewall blank, comprising the steps of:

• creating a lip on the bottom blank;
• wrapping a sidewall blank around the bottom blank so a sidewall blank flap having a bottom edge extends beyond the lip;
• forcing the bottom edge against a plurality of rollers having arcuate surfaces to direct the bottom edge inwardly;
• moving the rollers along the bottom edge;
• and
• forcing the bottom edge against a surface that is stationary with respect to the direction of movement of the rollers and configured to direct the bottom edge back towards the bottom blank.