Plastic article or earthenware shaping or treating: apparatus – Female mold and means to shape parison directly by internal... – Forming baffle – bottleneck – or handle
Reexamination Certificate
1999-04-08
2001-04-10
Davis, Robert (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Female mold and means to shape parison directly by internal...
Forming baffle, bottleneck, or handle
C425S535000, C425S537000, C425S806000
Reexamination Certificate
active
06213756
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to improvements in apparatus for the manufacture of thermoplastic containers by the extrusion blow molding process, a process that is occasionally referred to as the “shuttle” blow molding process. More particularly, this invention relates to improvements in apparatus of the foregoing character that permit the manufacture of containers with restricted outlets. The invention also relates to improvements in apparatus of the foregoing character that permit the manufacture of containers with more precisely formed rims. The invention also relates to improvements in apparatus of the foregoing character that permit the removal of the moil from the containers before the containers impact a removal conveyor.
BACKGROUND OF THE INVENTION
In the manufacture of thermoplastic containers by the shuttle blow molding process, the threaded or otherwise configured closure receiving neck portion of the container, which is commonly referred to as the “finish” of the container, is formed by a neck mold that is positioned against an outermost end surface of a body mold cavity in which the body portion of the container is blown from a previously extruded form or parison of the container. The blowing of the container is done by air or another gas that is introduced into the parison within the mold cavity by a blow pin that extends through the neck mold into the parison within the body mold. The blow pin reciprocates with respect to the neck mold and body mold, and an anvil of a hard material is positioned within an open-ended cavity on the outermost surface of the neck mold to prevent impact damage to the neck mold as the blow pin reciprocates with respect to the neck mold.
In the manufacture of thermoplastic containers by the extrusion blow molding process, heretofore it has been very difficult to produce a container with an internal control diameter at or near the top of its finish, the “C” dimension in industry nomenclature, than the minimum internal diameter at or near the bottom of the finish, the “I” diameter in industry nomenclature. However, for proper dispensing of the packaged product, when the packaged product is a liquid, it is often important that the size of the opening at the “C” dimension be substantially smaller than the “I” dimension. Heretofore, this has usually been accomplished by inserting a separate annular fitment in the outlet of the container finish. This added element, and the assembly step involved in its insertion in a container, however, add to the expense involved in the manufacture of restricted outlet liquid containers by the extrusion blow molding process.
Another problem encountered in the manufacture of thermoplastic containers by the extrusion blow molding process, according to prior art techniques, relates to dimensional variations in the rims of such containers resulting from the time required to properly cool the portion of the container to be removed from the rim, often called a “moil,” at the conclusion of the blow molding process.
Another problem encountered in the manufacture of thermoplastic containers by the extrusion blow molding process, according to prior art techniques, relates to the removal of the moils from the containers at the conclusion of the molding process, especially containers produced with a restricted outlet. Heretofore, stripper plates, which are conventionally used to remove moils from other types of extrusion blow molded containers, were not effective in removing moils from restricted outlet containers of such type, and such moils often disengaged from the containers in an uncontrolled manner upon impact of the containers with a removal conveyor.
BRIEF DESCRIPTION OF THE INVENTION
The aforesaid and other problems heretofore associated with the manufacture of containers by the extrusion blow molding process are solved by the apparatus of the present invention in which the container is provided with a “C” dimension that is substantially smaller than its “I” dimension, to eliminate the need for inserting a separate fitment into the container to be able to properly control the rate of flow of liquid from the container, and this is done by providing the anvil used in such process with an annular, transversely extending partition at an elevation that will occur within the finish of the container, near but below the rim of the container. Such anvil partition will then serve to mold a restricted diameter annular partition within the container neck in addition to performing its historical function of preventing neck damage to the adjacent neck mold of the apparatus, and the restricted diameter annular partition thereby formed within the container finish will be an integral part of a single piece container and finish.
The extrusion blow molded apparatus of the present invention also provides containers with more precisely defined finishes by the use of a blow pin assembly that exhausts spent cooling air in an annulus that surrounds a cooling air inlet tube, and the exhausted spent cooling air is exhausted from the annulus of the blow pin assembly against the moil portion of the container being molded, that is, the annular portion of the container that projects outwardly from the rim at the finish of the container, such moil portion normally being trimmed from the container during or after its discharge from the mold. This spent cooling air discharge technique serves to accelerate the cooling of the moil, and to a lesser extent the cooling of the finish itself, and this acceleration of the cooling rates in the region of the finish of the container will help to reduce the distortion of the container finish that occurs when finish cooling occurs more slowly.
The extrusion blow molding apparatus of the present invention also provides for the stripping, or removal, of the moil section of a blow molded container with a restricted outlet before the container is removed from the mold, and therefore before the container is impacted against a removable conveyer, an action that heretofore was not consistently possible. According to the present invention, at the conclusion of the molding cycle the mold opens and the blow pin assembly is retracted relative to the mold. The shoulder of a tube of the blow pin assembly is stopped by a pair of tube drop rods, and the stem of the blow pin assembly continues to rise. The moil of the container, now detached or partly detached from the container finish because it engages the exterior of the blow pin assembly, is held up by a stripper doughnut insert. The stem of the blow pin assembly continues to rise through the stripper doughnut insert, which causes the moil to disengage from the blow pin assembly and fall to a conveyer below the mold.
Accordingly, it is an object of the present invention to provide an improved extrusion blow molding apparatus for the manufacture of thermoplastic containers. More particularly, it is object of the present invention to provide improved apparatus of the foregoing character that can be used to manufacture containers with restricted outlets. It is also an object of the present invention to provide apparatus of the foregoing character that provides for accelerated cooling of the molded container in the region of the moil at the rim of the container to thereby improve the definition of the finish of the container. It is also an object of the present invention to provide apparatus of the foregoing character that is capable of stripping the moil of the container from the container prior to the discharge of the container from the mold in which it was blown.
For a further understanding of the present invention and the objects thereof, attention is directed to the drawing and the following brief description thereof, to the detailed description of the preferred embodiment and to the appended claims.
REFERENCES:
patent: 3209401 (1965-10-01), Mehnert
patent: 3585683 (1971-06-01), Wilson
patent: 3597793 (1971-08-01), Weiler
patent: 3657406 (1972-04-01), Delebarre
patent: 3769394 (1973-10-01), Latreille
patent: 3769793 (1973-11-01), Wilson
patent: 38
Atkins William P.
Czesak Theodore M.
Krall Thomas J.
Davis Robert
Owens-Brockway Plastic Products Inc.
LandOfFree
Extrusion blow molding apparatus for manufacture of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Extrusion blow molding apparatus for manufacture of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Extrusion blow molding apparatus for manufacture of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2475881