Paper making and fiber liberation – Processes and products – Article forming processes
Reexamination Certificate
1999-06-25
2001-04-03
Silverman, Stanley S. (Department: 1731)
Paper making and fiber liberation
Processes and products
Article forming processes
C162S348000
Reexamination Certificate
active
06210531
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to forming machines more particularly for producing components from a paper pulp or slurry. Egg separators and egg boxes are typical examples of components of this kind, although the same forming process or a similar one is, or may be, used to form containers and other articles for a variety of purposes.
BACKGROUND OF THE INVENTION
A known forming machine for making such components requires a relatively massive surrounding frame to withstand the pressures applied during a press operation at a press station of the machine. The force required to press the paper pulp or slurry into the required shape at the press station may be in the order of 20 tons or so and is usually provided by hydraulics. Consequently, the frame needs to be extremely strong to continually withstand the very considerable forces involved and the cost of the massive frame tends to add very considerably to the overall costs. The cost of the frame will depend upon the size of the machine itself but, typically, may be in the order of £135,000 or so. There may be other disadvantages of the machine related to providing the required pressing force; such disadvantages may relate e.g. to the additional bulk of the machine (i.e. hydraulic ram) and/or to additional noise or inconvenience of operation or even undue inefficiency. Furthermore, the press station is normally pre-set to press the article being formed under a particular pressure to a particular thickness. Thus, it tends to be disadvantageous that, since the machine has been preset to operate at a particular pressure to press a particular article to a certain thickness, there is little control to vary the applied pressure and/or thickness of the article (without resetting press dies) more particularly in a controlled way to vary the quality and/or characteristics of the article in an accurately predictable manner. Additionally, it may be that the temperature required for drying the pressed article is higher than need be the case and/or the drying time may be longer than need be the case. At least in some instances, known press stations may not be able to produce the required shape of an article accurately enough (e.g. a 1° or 2° angle on a product 100 millimeters deep). Furthermore, the actual finish on every surface of the article may not be suitably consistent (e.g. the inside surface of an egg box formed from paper pulp is usually irregular and not as aesthetically pleasing as the exterior).
It is believed that known forming production methods for articles made from paper or fibre may not provide an article which is of a similar quality to that which can be produced from plastics or polystyrene (at least in some respects) and this tends to adversely affect the marketability of articles formed from paper/fibre.
SUMMARY OF THE INVENTION
An object of the invention is to at least alleviate one of the aforementioned, or other, disadvantages associated with forming machines or press stations and/or to provide a forming machine (or press station) which is improved in at least some respect.
According to the invention there is provided a forming machine for forming articles from pulp or slurry, comprising a press station having upper and lower perforate dies mounted, in use, for relative reciprocatory movement towards and away from one another and each said die being housed, in use, in an associated one of a two part chamber, said chamber parts being arranged to seal together when moved towards one another, and means for evacuating the sealed chamber whereby a final part of relative movement of the dies towards one another is caused by the evacuation.
Further according to invention there is provided a press station for a forming machine for forming articles from a paper or fibre slurry, the press station including a chamber housing, in use, die means for forming an article and means to evacuate the chamber in order to press the article in the die means.
Further according to the invention there is provided a forming machine including at least one press station in accordance with the immediately preceding paragraph.
Still further according to the invention there is provided the combination of a forming machine in accordance with the immediately preceding paragraph and a relatively lightweight support frame (weight less than 7 tons and possibly not more than 2 tons and preferably 3 tons or less or 6 tons or less).
Still further according to the invention there is provided a method of forming an article by pressing the article in die means, said method comprising evacuating a chamber surrounding the die means to provide sufficient pressure to press the article.
Still further according to the invention there is provided an article when made by the method according to the immediately preceding paragraph.
According to the applicant, advantageously, the required press loading force may be attained relatively easily in accordance with embodiments of the invention, thus substantially obviating the need for a hydraulic pressure ram, and most significantly, enabling a relatively lightweight and much less costly frame to be used instead of a massive framework. In embodiments of the present invention the cost of the framework could be reduced by, for example, 40% or so. The saving in weight may be greater than 70% and preferably is greater than 40% or 50%.
In the press station, the die means may comprise an upper perforate die or die set co-operable with a lower perforate die or die set in order to press form an article from paper pulp when said dies/die sets are brought together. The dies/die sets will usually be relatively reciprocable towards and away from one another. It is possible that only the upper die/die set is movable.
The chamber evacuation means preferably comprises a vacuum pump and the degree of vacuum control applied is preferably variable, for example, by means of a vacuum valve (variable orifice valve). Additionally or alternatively, a vent valve may be provided to ambient (atmospheric) conditions surrounding the chamber.
The chamber is, preferably, in two main parts or halves that can seal together in use and, preferably, one or each main part/half has a slidably mounted external skirt (preferably a flanged skirt) and of said skirts may be provided with a seal co-operable with the opposing skirt to form a sealing effect when the chamber parts/halves are closed together. Stops may be provided to limit the retraction and/or extension movement of the skirt relative to the associated chamber part/half. Alternatively, one chamber part/half may be slightly larger than the other and be slidably and sealably engageable with the other. Preferably, at least one of said main parts or halves of the chamber is float mounted on a member for moving said chamber part/half towards and away from the opposing chamber part/half.
The forming machine may include a forming station associated with or serving a plurality of press stations.
Still further according to the invention there is provided an article (e.g. an eggbox) press formed from a paper or fibre slurry said article being smooth on all surfaces.
Still further according to the present invention there is provided a press station for a forming machine for forming articles from a paper or fibre slurry, the press station comprising one or more of the following features:
a) evacuation means to evacuate a chamber surrounding press dies in order to provide a pressing force;
b) a press die mounted on a floating head;
c) two chamber parts or halves, one or each having a slidably mounted skirt;
d) evacuation means as in a), said means being variable to vary the degree of vacuum in the chamber;
e) means for pressing an article with smooth surfaces in a controlled way.
Many advantageous features of the invention will be apparent from the following description and drawings.
REFERENCES:
patent: 4806195 (1989-02-01), Namysl
patent: 3814318 (1989-11-01), None
patent: 0 105 722 A1 (1984-04-01), None
patent: 0 406 783 A2 (1991-01-01), None
patent: 0 406 783 A3 (1991-01-01), None
patent:
Alston & Bird LLP
Halpern Mark
PX Technologies, Ltd.
Silverman Stanley S.
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