Method and apparatus for the continuous manufacture of rubber or polymer-based mixtures containing additives
AssigneeHermann Berstorff Maschinenbau GmbH
InventorsNorbert Rabiger, Manfred Dienst
Life of this patent
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Abstract
A process and an apparatus for continuously producing a rubber mixture. In the process, the constituents of the mixture are fed into a twin-screw extruder and are masticated and homogenized therein, with approximately 5% of the mixture being discharged and the remainder being recycled for further homogenization and for mixing with fresh batches of the constituents being fed into the extruder. The recycled mixture is circulated to and returned from a cooled, annular chamber dispersed exteriorly of the chamber of the twin-screw extruder, with the annular chamber having outflow and inflow passages communicating with the interior of the extruder.
Claims19
A method for the continuous production of a rubber-containing mixture in a twin-screw extrusion device comprising a housing, at least first and second feed apertures, and an outlet aperture adjacent the end of the extrusion device, comprising the steps of:
- (a) feeding rubber into said extrusion device through said first feed aperture and masticating said rubber,
- (b) metering additives to be admixed with said rubber through said second feed aperture, said second feed aperture being at a spacing from said first feed aperture of from about one to ten times the diameter of said screws,
- (c) mixing said additives with said rubber,
- (d) dividing said mixture of rubber and additives into first and second parts downstream of said second feed aperture at a spacing of up to about ten times the diameter of said screws,
- (e) discharging said first part through said outlet aperture,
- (f) feeding said second part, containing up to 20 times the quantity of said first part, into an annular chamber exteriorly of the extrusion chamber, said annular chamber having a length of at least about twice said screw diameter,
- (g) cooling said mixture in said annular chamber, and
- (h) returning said cooled second part into said extruder chamber utilizing the feed pressure of said extruder, said re-entry point of said cooled mixture lying upstream of said outlet aperture.
An apparatus for the continuous production of a rubber-containing mixture, comprising an extrusion device, said extrusion device comprising a housing;
- first and second intermeshing screws rotatable in said housing;
- first and second feed hopper means communicating with the interior of said housing;
- metering devices associated with each of said feed hopper means;
- said housing further defining an axial outlet means downstream of said feed hopper means, means for controlling said outlet means in dependence upon the pressure subsisting in said housing, and recycling means having first and second end regions communicating with said interior of said housing, said first end region of said recycling means lying in the region of, but upstream of, said outlet opening and said second end lying upstream of said first end, wherein said second hopper means is disposed downstream of said first hopper means at a longitudinal spacing of up to about ten times the diameter of said screws, wherein said recycling means comprises at least one outflow passage terminating in said first end region and extending radially from said housing, annular chamber means into which said outflow passage opens radially, said annular chamber comprising inner and radially outer wall surfaces, and extending co-axially with said housing and having a longitudinal length of at least twice said diameter of said screws, means for cooling said annular chamber, at least one inflow passage extending radially inwardly from said annular chamber and terminating in said second end region, and a cylindrical casing member including inner and outer wall surface, said inner wall surface of said casing forming said outer wall surface of said return chamber, said inner wall surface of said casing defining helical grooves therein, said helical grooves having a pitch for effecting the return of material in said chamber in an upstream direction.
An extrusion device for continuous production of a rubber-containing mixture, comprising:
- (a) a housing,
- (b) first and second intermeshing screws rotatable in said housing and defining with said housing an extrusion chamber for homogenizing said mixture,
- (c) first and second feed hopper means for receiving rubber and additives respectively, communicating with the interior of said housing, said second feed hopper being disposed downstream of said first hopper means at a longitudinal distance of up to about ten times the diameter of said screws,
- (d) outlet means adjacent the discharge end of said housing, and means for controlling the size of said outlet means dependence upon the pressure subsisting in said housing,
- (e) recycling means located exteriorly of said extrusion chamber for recycling said mixture and having first and second ends and an annular chamber therebetween, said annular chamber having a length of at least twice the diameter of each of said screws, said first end lying adjacent but upstream of said outlet means, and said second end lying upstream of said first end,
- (f) at least one outflow passage extending radially outwardly of said housing and communicating with said first end and said annular chamber of said recycling means, and at least one inflow passage extending radially from said housing and communicating with said second end and said annular chamber of said recycling means, and
- (g) means for cooling said annular chamber in order to cool said recycled mixture.
Dependencies are inferred from the claim text.