Plastic article or earthenware shaping or treating: apparatus – Female mold and means to shape parison directly by internal... – Including blowing medium supply means
Patent
1997-01-10
1998-08-11
Davis, Robert
Plastic article or earthenware shaping or treating: apparatus
Female mold and means to shape parison directly by internal...
Including blowing medium supply means
425534, B29C 4958
Patent
active
057924910
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention concerns a device intended to ensure impermeable sealing between the rough form of a plastic container and a blower nozzle in a machine for manufacturing containers by blowing or by stretching/blowing these rough forms.
The state of the art encompasses machines for the manufacture of plastic containers, each of which machines incorporates, in succession, a preform-feed section, a preform-handling section, a thermal treatment oven, a heated perform-handling section, a unit comprising molds equipped with means allowing blowing of the containers (normally after a stretching operation), a section for handling each container, and a container-output section.
The type of machine described above allows manufacture of a final container from a preform by implementing a single blowing step.
Conventional knowledge also encompasses machines allowing container manufacture using so-called "double blowing" procedures. Such a procedure, for example that described in commonly assigned French Patent No. 2 658 119, requires the use of two stations, each of which is equipped with a machine derived from the machine described above, these two stations being connected by a conveyor.
Container manufacture includes the following steps, which are described in detail in the aforementioned French patent: (stretching/blowing) of a semi-finished container; station; semi-finished container, then blowing of the final container.
The details of the manufacturing steps and the advantages of one method as compared with another are well known to those skilled in the art and do not constitute the object of the invention in question. They will, therefore, not be described in greater detail.
To further an understanding of the invention, it will be recalled that a preform is normally produced by injecting a plastic material in a suitable mold. The design of the preform and the quantity of material necessary for its manufacture depend on the design of the container to be blown. However, the basic structure is the same; that is, the perform exists as a tube open at one of its ends and sealed at the other.
The open end and an immediately-adjacent area form the neck of the preform. The shape of the neck is normally the final one and corresponds to the shape of the neck (the neck of a bottle) of the finished container. Accordingly, this shape is not modified during the subsequent blowing step(s).
Thus, if the preform is intended to yield a container to be sealed by a threaded plug, the neck is provided at the time of injection with threading having its final shape and dimensions. If, on the other hand, the container is to be sealed using a stopper, the preform neck is produced in a suitable shape and appropriate dimensions.
Furthermore, the design of the preform is such that it is easily unmolded from the injection mold. In most cases, the shape of at least the body is tapered, as a truncated cone having a larger diameter at the neck than at the bottom.
The sealed end forms the bottom of the preform, and the section extending between the bottom and the neck forms the body thereof.
Knowledge of the existence of an area called the shoulder of the preform, located between the neck and the body, and knowledge of the way in which the material composing the body and the bottom of the preform is distributed so as to form the body and the bottom of the finished container are not needed in order to understand the invention under consideration.
In the remainder of the description, the term "rough form" will be used to designate both a preform and a semi-finished container. In fact, a preform constitutes a rough form for the final or for the semi-finished container, depending on whether it is used in a single blowing or double blowing machine. Similarly, in a double blowing machine, the semi-finished container constitutes a rough form of the finished container.
Furthermore, in the rest of the description, the term "container" will be used to designate both a semi-finished container produced during a double blowing proce
REFERENCES:
patent: 4678425 (1987-07-01), Gibbemeyer
patent: 5340302 (1994-08-01), Ingram
patent: 5498152 (1996-03-01), Unterlander et al.
Davis Robert
Sidel S.A.
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