Apparatus and method for forming a partible port in a production piece

Abstract

Thermoforming apparatus and methodology is provided to form a breakaway port in a molded piece, such as a container lid. The apparatus includes a forging assembly that has a punch element and a striker assembly, so that a material blank that is heated to a plastic state by an oven may be advanced therebetween. When the thermoforming mold closes, a striker element and the punch element come together with a striking force so that a portion of the blank is forced against a male profile on the punch element to forge the port by forming lines of reduced thickness that are partible under mechanical force but which normally maintain the integrity of the molded piece against the passage of fluids. The striker element can be adjustably spring biased and can be mounted, for example, to the pressure box of the thermoforming mold while the punch element is positioned on the mold assembly that provides the mold configuration for the piece to be formed. When the thermoforming mold closes, the restorative force of the spring provides the striking force. The male profile is provided by ribs having a truncated triangular cross-section that provides the necessary geometry to create partible lines without severing the material of the production blank. The apparatus can perform a continuous cyclical process, and a trimming assembly can cut the molded pieces from a contnuous sheet of material advanced through the thermoforming mold.