Plastic and nonmetallic article shaping or treating: processes – Vacuum treatment of work – To degas or prevent gas entrapment
Reexamination Certificate
1998-08-31
2001-02-13
Ortiz, Angela (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Vacuum treatment of work
To degas or prevent gas entrapment
C264S268000, C264S269000, C264SDIG007
Reexamination Certificate
active
06187235
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for processing container closures, with a shaped liner, such as bottle caps, and more particularly, to a method for cooling, removing volatiles, and/or inspecting these closures. The invention also relates to an apparatus for processing bottle caps in the aforementioned fashion.
BACKGROUND OF THE INVENTION
In a number of industries it is desirable to use storage containers that seal. For example, glass bottles sealed with cover closures, called “bottle caps,” are used by beverage manufactures to store beverages. Bottle caps generally include a circular top panel, a cylindrical skirt extending from the peripheral edge of the top panel, and a liner. The liner is disposed on the inside of the top panel. The liner usually includes a raised sealing ring, which mates with the bottle to form a seal.
A number of different processing steps go into properly forming bottle caps. The liner, which is commonly formed of plastics such as polyvinyl chloride resin is molded into the cap at an elevated temperature. Formation in this way imbeds gases or volatiles within the liners. As the liners age, these gases can escape and reduce the purity and potentially the flavor quality of the bottle's contents. Therefore, it is desirable to have a process for removing these gases during manufacture.
In an effort to prevent bottle caps from sticking to various machine parts during processing, it is desirable to cool the liners after molding. U.S. Pat. No. 4,260,483 issued to Nicholson et al. discloses one method of cooling bottle caps using a cooling station with a conveyor belt. The belt moves slowly so that ambient air contacts and cools the liners. In this patent there is a concern about cooling the liners too quickly, so an enclosure is placed over the conveyor to further slow cooling. In order for this cooling station to work at a rate that is compatible with automated molding machine, rows of caps are processed on the conveyor at the same time. However, this type of set up may require a significant amount of space for the conveyor belt.
Another aspect of manufacturing bottle caps is related to a number of liner defects that occur. One defect occurs when the cap is formed without the liner. When a liner-free cap is applied to the bottle, this empty cap is not sealed. Another defect occurs when the liner sealing ring is formed with internal gaps or voids or formed in the improper shape. Any of these defects in the ring can result in a poor seal, which results in the undesirable consequences of air or contaminants entering the container. Another consequence is that a poor seal may lead to the contents of the bottle spoiling. For some applications, it is also considered a defect when a portion of the liner is molded on the cap skirt. This misplaced liner may prevent the cap from properly fitting on the container. If the cap is loose enough, the contents of the bottle may spill or the bottle may have a poor seal. A more serious consequence of the misplaced liner occurs when such a liner strains an automatic capping machine to the point where the glass container ruptures. If this occurs during manufacturing, the machines are stopped and possibly serviced, which is costly.
In an effort to minimize the consequences of defective caps, processing bottle caps typically includes inspecting the lined caps. Properly lined caps are shipped for use, and improperly lined caps are rejected and not used. Inspection can be manual or automated. In an automated, high-production environment it is desirable to inspect the caps at the cap processing rate, which is the speed at which the liners are molded. Since manual inspection is too slow to keep up with the cap processing rate, automated inspection machines are preferred.
Several patents have been issued which are directed towards automated inspection machines. For example, U.S. Pat. No. 3,724,655 issued to Clark discloses an apparatus for testing gasket thickness and sealing, and rejecting caps with gaskets that are not without a predetermined thickness range or that do not seal properly. The testing apparatus includes a memory wheel with movable pins. The position of the pins is used to sort unacceptable from acceptable caps. As the use of the memory wheel makes the testing apparatus complex and increases testing time; this solution is less desirable and thus not a preferred one.
The present invention is intended to provide a method and apparatus for processing lined caps in a simple yet efficient manner by cooling the lined caps, removing volatiles from the lined caps, and inspecting the lined caps while operating at the cap processing rate.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a method of processing bottle caps comprising the steps of molding a liner with a raised sealing ring having an upper surface inside the cap at an elevated temperature to form lined caps; and advancing a stream of lined caps from a first position to a second position while supplying cooling air to the lined caps to cool the liner sufficiently rapidly to form a skin at least on the upper surface of the sealing ring before the caps arrive at the second position. The skin prevents plastic deformation and sticking of the liner during further processing. In a preferred embodiment, the molding and advancing steps operate at the same cap processing rate. Advantageously, the method according to the present invention provides a rapid way of cooling lined caps.
In another embodiment, the method further includes the step of applying a vacuum to the liner, the vacuum is sufficient to remove volatiles from the liner. If the vacuum is applied within the raised sealing ring, it can create suction to lift properly formed lined caps from the advancing stream. In the most preferred embodiment, the same vacuum which removes volatiles also inspects the lined caps. This makes the processing extremely efficient, and the application of the vacuum is capable of matching the cap processing rate.
The present invention further provides an apparatus for processing a bottle cap. The apparatus is operatively associated with a molding machine for molding a liner inside of the cap at an elevated temperature to form lined caps. The liner includes a raised sealing ring having an upper surface. Specifically, the apparatus comprises a rotating first turntable for receiving the lined caps from the molding machine at a first position and advancing the lined caps to a second position; a cooler for supplying cooling air; and an open-ended enclosure that extends between the first position and the second position. Advantageously, the enclosure forms a channel through which the first turntable rotates, the enclosure is adapted to receive the cooling air in the channel, so that as the first turntable moves the lined caps from the first position to the second position through the channel the liner is exposed to the cooling air and is cooled. The cooler is preferably an air cooler that supplies cooling air.
In a preferred embodiment, the apparatus further includes a rotating second turntable, a vacuum pump, and at least one inspection station. The rotating second turntable receives the lined caps from the first turntable at the second position and advances the lined caps toward a third position. The vacuum pump draws a vacuum and applies it to the caps. The inspection station is coupled to the second turntable.
The inspection station preferably includes a housing, a vacuum tip, a stopper, and a spring. The housing defines a channel that is in fluid communication with the vacuum pump. The vacuum tip is connected to the working end of the housing and has a central passage for fluid communication between the channel and the exterior of housing. The stopper is movable between open and closed positions for selectively opening and closing the central passage. The spring is disposed within the channel, and biases the stopper into the closed position. When the inspection station is at the second position, the lined cap is disposed bel
Ortiz Angela
Pennie & Edmonds LLP
Zapata Technologies Incorporated
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