Extruder with supply conduit for supplying even flow of material

Details Extruder with supply conduit for supplying even flow of material Extruder with supply conduit for supplying even flow of material

1998-09-29

2000-07-11

Cooley, Charles E.

Agitating

Rubber or heavy plastic working

With specified feed means

366 98, 366305, B29B 758

Patent

active

060862394

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The invention relates to an extruder comprising at least two stators, the inner stator having at least an outer surface that is at least mostly conical and the outer stator having at least an inner surface that is at least mostly conical, at least one rotatable rotor that is at least mostly conical being situated between the stators, the extruder comprising a supply conduit for supplying material into the space between the stators, and the rotor comprising at the orifice of the supply conduit openings via which at least a part of the material to be fed is able to flow.


BACKGROUND OF THE INVENTION

U.S. Pat. No. 3,314,108 discloses an extruder comprising two conical stators and a conical rotor that is rotatably placed between the stators. The plastic material to be extruded is supplied via two different conduits to different sides of the rotor. The intermixing of the materials to be fed via different conduits is prevented with seals at the end where the material is supplied. The material is fed to the interior of the rotor in such a way that at the material supply conduit the rotor comprises openings through which the material can flow to the interior of the rotor. As the rotor rotates, the openings move past the orifice of the supply conduit whereupon the resistance acting on the material to be supplied along the conduit varies depending on the position of the opening with respect to the orifice. This causes a pumping effect in the material, deteriorating the rate of supply and the even distribution of the material.
European patent application 89 906 779.7 discloses an extruder comprising several conical stators, and conical rotors that are rotatably placed between the stators. The material to be extruded is supplied along one conduit to the beginning of each rotor, whereupon the rotor comprises at the inlet openings via which the material can also flow to the other side of the rotor. As above, the problem with this arrangement is that the resistance acting on the material to be supplied along the conduit varies as the rotor rotates and as the openings of the rotor simultaneously pass the orifice of the conduit.
The purpose of the present invention is to provide an extruder which comprises none of the aforementioned problems and in which the material to be extruded can be evenly supplied into the extruder.


SUMMARY OF THE INVENTION

The extruder according to the invention is characterized in that the end of the supply conduit and ducts formed of the openings and/or grooves of the rotor are designed in such a way that the sum of the areas of the parts of the ducts visible at the end of the supply conduit remains substantially constant at each moment when the rotor rotates.
An essential idea of the invention is that at the end of the conduit supplying material to the rotor, i.e. at the junction between the stator and the rotor, at each moment as the rotor rotates the sum of the areas of the rotor ducts visible at the end of the supply conduit remains substantially constant. Further, the idea of a preferred embodiment is that the width of the end of the supply orifice substantially equals the distance between the centers of the rotor ducts or a multiple of the distance. In such a case, material is supplied at least temporarily from the supply conduit to a minimum of two different rotor ducts simultaneously. The idea of yet another preferred embodiment is that the end of the supply conduit comprises an extension, whereupon the end of the supply conduit has a greater cross-section than the rest of the supply conduit. Further, the idea of a preferred embodiment is that the extension at the end of the supply conduit has a volume substantially equalling the volume of the rotor ducts situated at the extension. The idea of yet another preferred embodiment is that the extension at the end of the supply conduit has an asymmetrical form, i.e. the extension tapers off at the end.
The invention has the advantage that the material to be fed along the supply conduit can flow evenly from the suppl

REFERENCES:
patent: 2764780 (1956-10-01), Reifenhauser
patent: 2779054 (1957-01-01), Doriat et al.
patent: 2995346 (1961-08-01), Samples
patent: 3314108 (1967-04-01), Wienand et al.
patent: 3315944 (1967-04-01), Gustrau
patent: 5387386 (1995-02-01), Kirjavainen
patent: 5538343 (1996-07-01), Tynan
patent: 5674004 (1997-10-01), Takeuchi

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