Patent ID: 7568369

Claim:
A molding unit for shaping a container preform into a shaped container having a predetermined sidewall contour, the preform being supported on a tool which moves the preform into and out of the molding unit and supports the preform in the molding unit during a shaping process, the molding unit comprising: a two-part mold split vertically in half providing two mold sections with inner surfaces of the respective mold sections shaped to produce a specific container contour matching the shape of the inner surfaces; a pressurization unit positioned over an open end of the preform prior to closing the mold, a pressurized fluid being introduced into the preform through the pressurization unit after the mold is closed to force a sidewall of the preform outwardly against the inner surfaces of the mold sections to shape the preform to the specific container contour, a height of the preform contracting as a sidewall expands, the preform having a main body portion and a top piece attached thereto by a double seam, the pressurization unit including: a head comprising: a central opening whose sidewall is profiled to conform to the shape of the top piece for the head to fit over the top piece when the pressurization unit is lowered into place; and a circumferential nose fitting into a bottom surface of an annular channel of the top piece with a tip end of the nose bearing against the bottom surface of the channel, the head structured and operable to move downward as the preform contracts such that the nose exerts a downward force on the top piece as the height of the preform contracts, thereby controlling the direction of contraction and preventing distortion of the container; and a cap with an annular flange received within annular groove formed in an upper end of the mold sections to prevent movement of the cap when the mold is closed and until the mold sections are again separated at the completion of a molding operation, each mold section inner surface structured to provide space between each mold section and the top double seam such that the top double seam is not contacted by the mold sections or the nose of the pressurization unit head so to be unsupported by the mold and free to move during the shaping process, and the container preform having a lower end seated on the tool with the downward force imparted by the pressurization unit head on the preform preventing the lower end from lifting off the tool so that the height contraction of the preform occurs only from the upper end of the preform.