Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Layered – stratified traversely of length – or multiphase...
Reexamination Certificate
1998-09-09
2001-02-13
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...
C264S040600, C264S040700, C264S171290, C264S209200, C264S209800, C264S349000, C425S131100, C425S133100, C425S378100, C425S380000, C425S204000, C425S209000, C366S083000, C366S152100, C366S160100
Reexamination Certificate
active
06187237
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method for making a product to be extruded, in which method material to be extruded is fed into an extruder comprising at least two conical feed gaps placed one within the other in the radial direction and positioned between a rotatable rotor and a stator, whereupon the material to be extruded is supplied separately to each feed gap.
The invention further relates to an extruder comprising at least two conical feed gaps placed one within the other in the radial direction and positioned between a rotatable rotor and a stator, at least two supply conduits for feeding the material to be extruded separately into each feed gap, and feeding devices for feeding material along the supply conduits.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 3,314,108 discloses an extruder comprising two conical stators and a rotor placed rotatably between the stators. This apparatus comprises supply conduits along which a material to be extruded can be supplied in such a way that the material is fed along one supply conduit into the exterior of the rotor and along the other supply conduit into the interior of the rotor via openings provided therein. The apparatus enables the manufacture of, for example, two-layer plastic pipes, but the layer thicknesses of the pipe or the temperature of the material to be extruded cannot be regulated or changed in any way.
EP 0 422 042 discloses an extruder comprising at least three conical stators and at least two conical rotors placed between the stators. The material to be extruded is fed between the rotor and the stator via supply conduits. The rotors also comprise openings via which the material to be supplied can also enter the rotor and flow to the space between the rotor and the stator provided inside it. The apparatus provides for example multilayer pipes, but it is not possible to regulate the properties of the different layers with respect to each other. Also, the temperature of the materials on different sides of the rotor is the same on each side and there is no possibility of cooling from the outside. Further, regulation of the temperature of the material to be extruded in the extruder must be carried out with difficult separate heating arrangements.
DE 1 454 762 discloses an extruder comprising two feeding devices with an adjustable feed rate. The feeding devices supply the different components of the mass to be extruded to the space around the screw in such a way that the mass components are mixed at the beginning of the screw, whereupon the extruder produces a mass that is a mixture of different components. The screw is used to extrude a one-layer product, whereupon the mixing ratio of the mass components supplied from the different feeding devices is regulated by adjusting the feeding devices. Therefore the apparatus can only provide a mixed one-layer product.
CH 392 045 discloses an apparatus comprising a feeding device which can be used to adjust the amount of the mass flow to be supplied. Also in this case, the mass flow is supplied to the space surrounding the screw, by means of which a one-layer product is extruded, i.e. the apparatus cannot produce products where the properties of the different layers are adjusted separately.
EP 0 153 715 discloses an extruder where material to be extruded is supplied from two hoppers to the outer surface of a tubular rotor. The tubular rotor is provided with grooves such that the materials arriving from different hoppers are first passed to different directions at the outer surface of the rotor and thereafter via the ends of the rotor to the interior thereof. The apparatus is further provided with force-feed rings by means of which the speed of travel of the material at the surface of the rotor can be regulated. The regulation requires a complicated and cumbersome construction in order to be successful, since the force-feed rings require two large rotating drive motors that must rotate against the direction of rotation of the rotor. Further, the feed rings themselves grind the material. The supply arrangement does not in any way ensure the flow of a sufficient amount of the material forward, either, but for example if the supply conduit becomes clogged, it is not possible to supply a sufficient amount of material forward by means of the feed rings even with high speeds of rotation. Further, in the apparatus the regulation of the temperature of the material must be carried out, if desired, with difficult external heating or cooling devices.
SUMMARY OF THE INVENTION
The purpose of the present invention is to provide a method and an apparatus with which the properties of the different layers of the product to be extruded can be adjusted in a simple and easy manner.
The method according to the invention is characterized in that each of the material flows to be supplied is adjusted separately and the speed of rotation of the rotor is adjusted, whereupon the temperature of the material to be extruded is adjusted by regulating the amount of the material flows and the speed of rotation of the rotor.
Further, the extruder according to the invention is characterized in that each supply conduit is provided with a separately adjustable feeding device for regulating the material flow to be supplied via the supply conduit, and that the extruder comprises means for adjusting the speed of rotation of the rotor, whereupon the temperature of the material can be adjusted by regulating the amount of the material flows and the speed of rotation of the rotor.
The essential idea of the invention is that the extruder comprises at least two feeding devices, whereupon the material to be extruded can be supplied along different supply conduits separately to each conical feed gap. The amount of the material flow to be supplied can be adjusted with the feeding devices, and it is thus possible to influence the degree to which the space between the rotor and the stator is filled and therefore the amount of heat generated by friction and the thickness of the layers obtained. The adjustment of these parameters naturally affects the properties of the final product. Further, the idea of an embodiment is that the speed of rotation of the rotor can be adjusted, whereupon it is possible to regulate the amount of heat that results from friction and that affects the material. The idea of another preferred embodiment is that the extruder comprises at least two rotors, and that both sides of the rotors are provided with screw-shaped grooves for supplying material to the nozzle of the extruder, and at least one set of the screw-shaped grooves of at least one rotor have a different cross-section than the grooves of the other rotors, and that the positioning of the rotors with respect to each other can be changed. In such a case, depending on the positions of the rotors with respect to each other, it is possible to prepare a product having properties that depend on the order of the rotors.
The invention has the advantage that with the method and apparatus according to the invention, the properties of the final product can be adjusted easily and in various ways.
REFERENCES:
patent: 3314108 (1967-04-01), Wienand et al.
patent: 3865913 (1975-02-01), Lachner et al
patent: 3921963 (1975-11-01), Neff et al.
patent: 3966861 (1976-06-01), Papesh et al.
patent: 4420451 (1983-12-01), Rasmussen
patent: 4521368 (1985-06-01), Mercer et al.
patent: 4820464 (1989-04-01), Sasaki et al.
patent: 5358327 (1994-10-01), Derezinski et al.
patent: 5387386 (1995-02-01), Kirjavainen
patent: 392045 (1965-09-01), None
patent: 372214 (1923-03-01), None
patent: 1454762 (1969-05-01), None
patent: 0153715 (1985-09-01), None
patent: 0422042 (1995-01-01), None
patent: 8911961 (1989-12-01), None
Jarvenkyla Jyri
Kirjavainen Kari
Eashoo Mark
Ladas & Parry
Nextrom Holding S.A.
Silbaugh Jan H.
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