Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Layered – stratified traversely of length – or multiphase...
Reexamination Certificate
1998-09-08
2001-08-14
Silbaugh, Jan H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Layered, stratified traversely of length, or multiphase...
C264S209200, C264S211210, C425S113000, C425S133100, C425S378100, C425S381000
Reexamination Certificate
active
06274071
ABSTRACT:
FIELD OF INVENTION
The invention relates to a method for preparing an extrudable product, wherein the material to be extruded is pressed in the extruder along at least two annular feed gaps that are placed one within the other in the radial direction and that are provided between a rotor and a stator, the material to be extrudable being pressed from the extruder by rotating the rotors.
The invention further relates to an apparatus for preparing an extrudable product, the apparatus comprising at least two annular feed gaps that are placed one within the other in the radial direction and that are provided between a stator and a rotatable rotor, the material to be extruded being pressed from the extruder by rotating the rotors.
The invention also relates to an extruded product that is radially oriented at least at the outer surface.
BACKGROUND OF THE INVENTION
U.S. Pat. 3,314,108 discloses an extruder where a rotatable rotor is placed inside the frame and a fixed mandrel is further placed inside the rotor, whereupon feed gaps are formed between the rotor and the frame and the rotor and the mandrel, respectively, the material to be extruded being supplied out of the extruder via the feed gaps by rotating the rotor provided with grooves. In such an extruder it is very difficult to control the temperature of the material to be extruded since it can only be performed either via the external frame or the internal mandrel. If the product to be extruded is to be provided with circumferential orientation, a separate orientation tool that is placed after the nozzle must be used in connection with the extruder in question and also with other typical extruders. This kind of an arrangement is disclosed for example in WO 95/24304. Adding such a separate orientation tool naturally makes the apparatus complicated and difficult to use. Further, for example when films are extruded it is necessary to use some other similar difficult rotating arrangement to compensate for the variation in thickness.
DE 1,961,078 discloses an extruder where a rotatable rotor is mounted in bearings inside the frame and where a conical stator is placed inside the rotor, whereupon between the rotor and the stator there is a conical feed gap along which the material to be extruded is pressed out of the nozzle of the apparatus by means of rotor grooves as the rotor rotates. In this case, too, it is difficult to control the temperature of the material to be extruded since the temperature can only be regulated for the part situated inside the feed gap. Further, cooling of the rotor is a considerable problem since the rotor is encased inside the frame. Also, the extruder requires a separate tool placed after the nozzle for the orientation or the compensation of variation in thickness. The structure of the extruder is altogether rather cumbersome and difficult.
The purpose of the present invention is to provide a method and an apparatus where the aforementioned problems can be avoided. Another purpose is to provide an extruded product with very good properties.
SUMMARY OF INVENTION
The method according to the invention is characterized in that the stator is situated between the feed gaps such that outside the outermost feed gap there is a rotor and inside the stator there is at least one rotor.
Further, the apparatus according to the invention is characterized in that the stator is situated between the feed gaps such that outside the outermost feed gap there is a rotor and inside the stator there is at least one rotor.
Also, the extruded product according to the invention is characterized in that the product comprises axial continuous fibers within its material.
The essential idea of the invention is that the extruder comprises at least two annular feed gaps between which there is a fixed stator, and a rotatable rotor is provided outside the outermost feed gap. Inside the stator there is at least one rotatable rotor. The idea of a preferred embodiment is that continuous fibers are supplied through the stator. The idea of another preferred embodiment is that the fibers can also be supplied through the rotatable rotor or a sleeve. Also, the continuous fibers can be stretched by stretching the product to be extruded on which the continuous fibers are supplied.
The invention has the advantage that the product to be extruded can be provided with radial orientation without a separate orientation unit. Another advantage is that for example during the preparation of films the variation in thickness can be compensated for in a very easy and simple manner with the apparatus. Also, it is easy to place heating and cooling means inside the stator so that the temperature of the material to be extruded can be controlled easily and effectively when the means for controlling the temperature are situated between the different layers of the product to be extruded, which is in practice impossible in connection with a conventional extruder. With the apparatus according to the invention it is equally easy to process plastic that is in the form of powder and granulate without changing the structure of the apparatus. Further, when continuous fibers are supplied with the apparatus, it is possible to prepare a very strong product which comprises a radial orientation field and axial continuous fibers as reinforcement.
REFERENCES:
patent: 3289250 (1966-12-01), Zernay
patent: 3289251 (1966-12-01), Daubenfeld
patent: 3303251 (1967-02-01), Heider et al.
patent: 3314108 (1967-04-01), Wienand et al.
patent: 3490097 (1970-01-01), Gould
patent: 3712783 (1973-01-01), Maxwell
patent: 3862868 (1975-01-01), Spillers
patent: 4822548 (1989-04-01), Hempel
patent: 5108682 (1992-04-01), Tompkins et al.
patent: 5292472 (1994-03-01), Tompkins et al.
patent: 5387386 (1995-02-01), Kirjavainen
patent: 5393536 (1995-02-01), Brandt et al.
patent: 6013222 (2000-01-01), Douglas et al.
patent: 1961078 (1971-06-01), None
patent: 144708 (1954-03-01), None
patent: 9524304 (1995-09-01), None
Jarvenkyla Jyri
Kirjavainen Kari
Eashoo Mark
Ladas & Parry
Nextrom Holding S.A.
Silbaugh Jan H.
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