Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With accumulator – trap chamber – or serially arranged valves...
Patent
1996-12-23
1998-09-29
Heitbrink, Tim
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With accumulator, trap chamber, or serially arranged valves...
425558, 425560, 425561, B29C 4578
Patent
active
058143580
DESCRIPTION:
BRIEF SUMMARY
INJECTION MOLDING APPARATUS FOR PROCESSING THERMOPLASTIC MATERIALS
The invention concerns an injection molding apparatus for processing thermoplastic materials, which has at least one plasticizer unit, at least one injection molding cylinder with associated piston for emptying said cylinder and at least one injection molding mold.
In view of the fact that plastic materials, for example PET, which set high levels of requirement in regard to the operating conditions in the processing operation are increasingly also used for injection molding, it is necessary for the injection moulding machines to be so designed that they take account of those requirements so that it is possible to manufacture a product which satisfies all qualitative demands. For that purpose, as far as possible the plasticizer unit should be operated continuously, that is to say the screw which is generally provided in such a plasticizer unit should rotate continuously independently of the successive working cycles in order to be able to maintain a pressure which is as uniform as possible within the plasticizer unit. Continuous operation of the plasticizer unit is also advantageous in terms of circumstances which remain uniform as far as possible, in regard to other operating conditions and parameters, for example temperature and viscosity of the plasticized material. In addition, to achieve good quality for the end products, another aim is that the flow paths between the plasticizer unit and the injection molding tool should also experience as few fluctuations as possible and/or as slight fluctuations as possible, in regard for example to pressure, temperature and viscosity, in particular also with the aim of providing for careful and gentle treatment of the plastic material, for example in such a way as to avoid abrupt alterations in direction at a high flow speed as well as abrupt changes in the flow speed, but in particular also very high flow speeds and/or narrow flow cross-sections.
An injection molding machine which at least substantially takes account of those requirements should also be of a compact and space-saving design configuration, in particular in regard to the configuration and arrangement of flow ducts and injection molding cylinders, in relation to the level of productivity thereof, so that if necessary it is possible to associate with a plasticizer unit a plurality of injection molding tools which are alternatively charged with plastic material, by the plasticizer unit. Such an arrangement is based on the consideration that in many cases, in view of the time which is required in a working cycle for injection of the plastic material into the respective injection molding tool, cooling of the plastic material in that tool and removal of the finished article from the tool, a plasticizer unit of a suitable size should charge at least two injection molding tool units in order in that way to make the maximum possible use of the available output of the plasticizer unit.
German patent specification No 1 105 153 already discloses an injection molding machine for processing thermoplastic materials, in which the plastic material coming from a plasticizer unit which is in the form of a screw press is firstly conveyed into a pressure chamber disposed downstream of the plasticizer unit, wherein at the same time the plasticizer unit is displaced in the opposite direction to the direction of flow of the plastic material, in accordance with the increase in the volume of plastic material in the pressure chamber. After termination of the post-pressure phase for the plastic material which was introduced into the injection molding mold in the preceding working cycle, the plastic material in the first pressure chamber is conveyed by suitable actuation of the co-operating parts of the machine from the first pressure chamber through a one-way valve arranged between both chambers, into a second pressure chamber, while at the same time the plasticizer unit is pushed back again into its starting position at the beginning of the operation of fillin
REFERENCES:
patent: 3175248 (1965-03-01), Swenson
patent: 3707248 (1972-12-01), Aker
patent: 5011399 (1991-04-01), Farrell
patent: 5605707 (1997-02-01), Ibar
Heitbrink Tim
Krupp Kautex Maschinenbau GmbH
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