초록 ▼

A molding unit (20) for use in a can shaping process. Container preforms (F) are mounted on a table (16) which is rotated so a blank is moved from an initial loading station (P1) to a molding station (P4). The molding unit includes a two-part mold (20a, 20b) split vertically in half, and an inner s

A molding unit (20) for use in a can shaping process. Container preforms (F) are mounted on a table (16) which is rotated so a blank is moved from an initial loading station (P1) to a molding station (P4). The molding unit includes a two-part mold (20a, 20b) split vertically in half, and an inner surface (56) of each mold half is shaped to produce a desired can profile. Once the preform is in place, a pressurization unit (102) is lowered into place from above the mold onto an open, upper end of the preform. The mold is then closed and pressurized air is introduced into the preform and forces the sidewall of the preform outwardly against the inner surface of the mold to conform the preform into a desired container profile. The height of the preform tries to contract as its sidewall expands, but a force imparted to the preform by the pressurization unit controls the direction of any contraction so to prevent distortion of the container. After the shaping operation is complete, the pressurized air is withdrawn from the container, the mold is opened, and the pressurization unit is removed. The table is rotated to an off-loading station (P7) where the shaped container is removed from the table and conveyed to the next operating location. As the table moves the contoured container to the off-loading station, another container preform is loaded into the mold.

대표청구항 ▼

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is: 1. 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 m

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is: 1. 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. 2. 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 preform including a hollow central body portion, a top piece with a central opening therein, and a bottom piece closing the bottom of the preform, the top and bottom pieces each being attached to respective ends of the central body portion by a double seam, 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, the mold having a first groove at an upper end of the mold and a second groove at the lower end of the mold; a pressurization unit positioned over the upper end of the preform prior to closing the mold for a pressurized fluid to be 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 desired container contour, the pressurization unit including a cap having a flange received in the first mold groove to prevent movement of the cap when the mold is closed and further including a head having a central opening whose sidewall is profiled to conform to the shape of the preform to piece to over the top piece of the preform and having a nose received in a channel formed about an outer margin of the top piece, the head structured and operable to move downward as the sidewall of the preform is forced against the inner surfaces of the mold sections by the pressurized fluid such that a tip end of the nose bears against the bottom of the channel and exerts a downward force on the preform during pressurization, each mold section inner surface structured to provide space between each mold section and the double seam by which the top piece is attached to the central body portion of the preform such that the double seam by which the top piece is attached to the central body portion of the preform is not contacted by either of the mold sections or the pressurization unit when the mold is closed so to be unsupported thereby and free to move during the shaping process; and, the bottom piece of the preform being seated on the tool which has a flange received in the second mold groove to prevent movement of the tool when the mold is closed, the tool structured such that the double seam by which the bottom piece is attached to the central body portion of the preform overhangs an upper end of the tool and extends away from a side of the tool when the mold is closed so to not be in contact with the tool and thereby be unsupported and free to move during the shaping process, whereby, during a molding operation, the downward force imparted by the pressurization unit head on the preform prevents the lower end of the preform from lifting off the tool so that any shrinkage in height of the container occurs only from the upper end of the container and the respective double seams are unrestrained and free to move. 3. The molding unit of claim 2 in which the inner surfaces of the mold sections above the second groove have inwardly extending lower stepped recesses formed adjacent the double seam connecting the bottom piece to the central body portion of the preform the lower recesses structured to provide space between each mold section and the double seam connecting the bottom piece to the central body portion of the preform such that the double seam connecting the bottom piece to the central body portion of the preform will not contact the mold during the shaping process. 4. The molding unit of claim 3 in which the lower recesses are each a stepped recess that provides a space between each respective double seam and the inner surfaces of the mold sections, each recess extending above the height of each respective double seam such that the inner surfaces of the mold sections do not contact the respective double seam when the mold is closed. 5. The molding unit of claim 1 in which the mold sections have a second annular groove formed at their lower end and the tool has an annular flange received in said second groove, the annular flange being captured in the second annular groove when the mold is closed whereby the tool is prevented from moving until the mold sections are again separated at the completion of the shaping process. 6. The molding unit of claim 5 in which the preform also includes a bottom piece which is attached to the main body portion thereof by a double seam said tool structured such that the bottom double seam will overhang a side of the alignment tool, the inner surfaces of the mold sections having inwardly extending lower stepped recesses formed adjacent the bottom double seams so, the lower stepped recesses being structured to provide space between the mold sections and the bottom double seam such that the bottom double seam is not contacted by the mold sections during the shaping process. 7. The molding unit of claim 6 in which the lower recesses are stepped recesses that provide space between each double seam and the inner surfaces of the mold sections, the recesses extending above the height of each respective double seam such that the inner surfaces of the mold sections do not contact the respective double seam when the mold is closed. 8. The molding unit of claim 5 further including a groove formed in the head adjacent a shoulder of the top piece, an O-ring being received in the groove to seal off the outside of the preform from the air pressure inside the preform during the shaping operation, there being no pressure seal formed between the mold, when it is closed, and the atmosphere, so that there is no equalization of the pressure between the inside and outside of the preform during the shaping process.