Cutting – With product handling means – Means to move – guide – or permit free fall or flight of product
Reexamination Certificate
2000-05-26
2001-11-06
Peterson, Kenneth E. (Department: 3724)
Cutting
With product handling means
Means to move, guide, or permit free fall or flight of product
C083S681000, C083S914000, C083S946000, C425S527000, C425S806000
Reexamination Certificate
active
06311593
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for trimming the neck of a blow molded plastic container. More specifically, the present invention relates to a post molding apparatus for trimming a plastic ring from the inner diameter of the neck of a blow molded plastic container to provide a clean circular sealing surface for engagement with a sealing cap.
2. Description of the Prior Art
Plastic containers, such as containers filled with milk and other liquids, are typically blow molded. If the container is blow molded with a blow pin, neck finishing is often accomplished using a pull up or ram down shearing tool on the blow pin. However, some containers are blow molded through use of blow needles and these containers require removal of the container from the blow mold for post mold trimming. During post mold trimming, a blow dome attached to the container is first removed through a guillotine or spin trimming operation. With the blow dome removed, small V-grooves in the inner circumference of the sealing flange of the neck can be seen and are an inherent result of the blow molding process. The V-grooves, located 180° apart (where the pinch-off of the mold halves compress the molten parison) create a disruption in the sealing surface of the container and can cause leakage around the cap.
Two type of caps are typically employed to seal such containers and these include a linerless threaded cap and a snap-on cap. With a linerless threaded cap, the cap is threaded onto the external threads of the container neck and an interiorly formed ring on the cap extends inside of the sealing flange of the container. Preferably, the ring contacts the interior edge of the sealing flange forming a seal closing off the bottle. Clearly, the V-grooves mentioned above might compromise the sealing capability of such a cap. The same is true for snap-on caps. These caps also include an interior ring which extends inside of the sealing flange to engage against the interior edge forming a seal that closes off the container.
In order to ensure that the V-grooves do not compromise the sealing capabilities of the container and cap, the inner diameter of the sealing flange is finished in a post molding operation. Removal of the V-grooves can be done by a reaming and/or facing process. During reaming, a reamer extends into the opening and cuts away portions of the neck flange. However, this generates plastic chips which can enter into the container. The chips must then be removed. Otherwise, the product is contaminated.
In view of the drawbacks and limitations of the prior art, it is seen that there exists the need for a simplified trimming apparatus which provides for a clean inner diameter in the sealing flange of a blow molded container.
It is therefore a principle object of the present invention to provide a trimming apparatus which fulfills that need.
Another object of the present invention is to provide an inner diameter neck trimming apparatus which forms a precise, uniform aperture in the sealing flange of the container without creating chips of plastic material which can potentially enter into the bottle.
A further object of this invention is to provide such a mechanism with a compact construction, minimal complexity, low cost, easy servicing requirements and the potential for retrofiltering into existing machinery.
SUMMARY OF THE INVENTION
The neck trimming apparatus according to the present invention trims a continuous ring of material from the inner diameter of the sealing flange utilizing a reverse punch. The punch is mounted on the end of a shaft and includes a trailing edge that defines the cutting surface of the punch. The neck of the container is held within a nest, with its sealing flange being adjacent to a die. The punch is advanced through the opening in the die with its cutting surface being moved to a position within the neck of the container and the untrimmed sealing flange. Upon withdrawal of the punch out of the neck of the container, the cutting surface of the punch, in cooperation with the die, trims a ring of material from the inner diameter of the sealing neck leaving a clean circular opening in the sealing flange. The severed ring is continuous and is retained around the shaft, above the punch, by virtue of an undercut formed in the shaft relative to the outer diameter of the punch. Mounted to the shaft, generally adjacent to the punch, is a knife having a cutting edge facing outward from the shaft. On the opposing side of the shaft, and also mounted thereto, is a stripper arm. The stripper arm is pivotably mounted to the shaft with one end being located adjacent to the punch. The opposing end of the arm is biased laterally outward by a spring such that the end adjacent to the punch is biased against the shaft.
In order to remove the ring from about the shaft, an actuator engages and pushes on that end of the stripper arm away from the punch. This causes the arm to pivot about its pivot point with the end of the stripper arm adjacent to the punch being pivoted laterally away from the shaft. This action pushes on the ring causing the opposite side of the ring to engage the cutting edge of the knife, severing the ring and thereby allowing it to be removed from around the shaft.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates from the subsequent description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.
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patent: 3108374 (1963-10-01), Bowman et al.
patent: 3145243 (1964-08-01), Hagen
patent: 3369272 (1968-02-01), Martin et al.
patent: 5664471 (1997-09-01), Dundas
patent: 5682804 (1997-11-01), Moore
patent: 5749275 (1998-05-01), Dundas et al.
patent: 5791217 (1998-08-01), Dundas et al.
patent: 6158317 (2000-12-01), Maddox et al.
Maddox A. Dale
Shapler Thomas A.
Thompson James E.
Brinks Hofer Gilson & Lione
Peterson Kenneth E.
Uniloy Milacron Inc.
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