Plastic article or earthenware shaping or treating: apparatus – Preform severing means – Serially arranged with preform reshaping means
Patent
1994-06-23
1996-07-16
McMahon, Timothy
Plastic article or earthenware shaping or treating: apparatus
Preform severing means
Serially arranged with preform reshaping means
2411012, 2411863, 264140, 4253051, 425306, A21C 1110
Patent
active
055361544
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to an apparatus for treating thermoplastic synthetic plastics material, for example waste, in particular of polyester, comprising a receptacle for material to be treated to which this material is supplied through an intake opening and from which the material is delivered by at least one worm connected to the sidewall of the receptacle, at least one tool having working edges acting comminuting and, respectively, or mixing on the material disposed in the bottom region of the receptacle and being rotatable around a vertical axis, the intake opening of the worm being disposed at least substantially at the level of the tool, and at least one line connected to the receptacle for creating a vacuum within the interior of the receptacle and, if desired, for supplying a gas therein.
Such apparatus are known (EP-A 390,873), and generally they work satisfying, also when treating such kinds of synthetic plastics material which are sensitive to air oxygen and, respectively, or humidity, because by evacuating the receptacle or by supplying a protective gas into the interior of the receptacle, the synthetic plastics material can be protected against these detrimental influences.
However, it has been shown that in some cases the degree of homogenizing of the synthetic plastics material delivered by the worm is not sufficient, in particular with respect to the obtained drying degree of such synthetic plastics material which must be completely dry already before plasticizing in order to avoid downgrading, for example polyester. Polyester elements, for example foils of greater thickness, require an increased effort in drying which increases with the thickness so that for such material separate drying processes, for example with dehydrated air in special drying apparatus are required. Further, these drying apparatus operate in a temperature region that is admissible for crystalized material only, however, amorphous material would get sticky so that it would agglomerate. This means that a crystallizing process must antecede the drying process. However, if the material to be treated is treated for a long time in the receptacle, then at a continuous operation of the apparatus there occurs the danger that single synthetic plastics material elements are already clutched by the delivery worm already at a very early moment, however other synthetic plastics material elements only at a very late time. Those synthetic plastics material elements which were taken along early, may still be comparatively cold and, therefore, not pre-treated to a sufficient amount, so that the said inhomogenities in the material occur that is supplied by the worm to the connected tool, for example to an extruder head.
The invention has at its object to avoid these disadvantages and to substantially improve the homogenity of the delivered material, by using the vacuum effect within the receptacle in an advantageous manner. The invention solves this task by the features that the delivery opening of at least one further receptacle is connected to the intake opening by means of a tube element, in which receptacle also at least one tool rotating around a vertical axis is disposed in the bottom region of the receptacle, and that in the tube element a shut-off means for pressure-tight closing of the tube element is disposed for maintaining the vacuum within the interior of the receptacle provided with the line. Therefore, within the inventive apparatus two or more receptacles are disposed in a series and the synthetic plastics material to be treated must run through these receptacles one after the other. Within the first receptacle, already a pre-treatment of the synthetic plastics material takes place by a pre-comminuting, pre-heating, pre-drying and pre-compression, so that pre-homogenized material is created which is supplied to the following receptacle. Thereby it is ensured that no untreated (cold, not compressed, not comminuted or inhomogeneous) material is directly supplied to the delivery worm a
REFERENCES:
patent: 4222728 (1980-09-01), Bacher et al.
patent: 4243625 (1981-01-01), Burge
patent: 4460277 (1984-07-01), Schulz et al.
patent: 4968463 (1990-11-01), Levasseur
patent: 5017110 (1991-05-01), Wanek et al.
patent: 5225137 (1993-07-01), Sadr
Bacher Helmut
Schulz Helmuth
Wendelin Georg
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