The facility for manufacturing a profile strip made from several elastomer mixtures with different compositions by coextrusion includes at least two extruders which feed elastomer mixtures to an extrusion head. The extruders discharge directly into the extrusion head, which is interchangeable and groups together all of the dimensional tooling.

A meshing-type rubber internal mixer and a working method thereof are provided. The meshing rubber internal mixer includes a frame mechanism, a mixing mechanism, and an unloading mechanism. The mixing mechanism is on the upper side of the unloading mechanism. The mixing mechanism and the unloading mechanism are in the frame mechanism. An internal mixing chamber is of a closed structure through first automatic telescopic plates and second automatic telescopic plates. The gap between a first meshing-type rotor and a second meshing-type rotor is small, a material is compressed to enter the space between the first meshing-type rotor and the second meshing-type rotor to be extruded with an internal mixing chamber wall. The material is flaky in the internal mixing chamber, so that the material produces great strain deformation, thereby achieving excellent dispersing and mixing effects.

A planetary roller extruder section forms a feed part of an extruder. The planetary roller extruder has an internally toothed housing and an externally toothed central spindle disposed centrally within and at a distance from the housing. Planetary spindles are arranged to rotate in a void between the central spindle and the housing. Each planetary spindle has an external toothing meshing with both the housing and the central spindle. At least one planetary spindle has two axially spaced areas with less than a full set of teeth. Those axially spaced areas include a first area having a first number of teeth and a second area having a second number of teeth. The second number of teeth is less than a full set of teeth and more than the first number of teeth.

A machine for mixing elastomeric materials with a drive and mixing unit where the mixing chamber is arranged downstream of the drive unit; and a discharge chamber is arranged downstream of the mixing chamber. They communicate towards upstream, and are provided with a discharge opening for discharging the mixture. They include a signal indicating the presence or absence of a mixture. The machine can cause during a mixing step, at least one reversal by the drive unit of a sense of rotation of the rotors and therefore of a sense of advancing movement in the axial direction of the mixture from/towards the mixing chamber and towards/from the discharge chamber, to keep mixing of the mixture active only inside the mixing chamber.

A Machine for mixing elastomeric materials with a mixing unit, and a drive unit; the mixing unit has a mixing chamber arranged downstream of the drive unit and closed by a rear wall, a discharge chamber arranged downstream of the mixing chamber, with which it communicates and provided with an opening for discharging the mixture; a pair of inter-penetrating and counter-rotating conical rotors connected with the drive unit and having their vertices situated at the mouth of the discharge chamber. The rotors are rotated by the drive unit in a first sense (RPM+) to cause the mixture to be pushed towards the rear wall of the mixing chamber so as to keep mixing active only inside the mixing chamber, and in second sense of rotation, opposite to the first sense, to cause the mixture to be pushed towards the chamber and the discharge opening for discharging thereof.

A method for producing a resin composition of the present invention is a method for producing a resin composition, the method including a step of obtaining a resin composition by heating and melt-kneading a mixture containing a particulate nucleating agent in which D.sub.50 is equal to or more than 0.1 μm and equal to or less than 300 μm and a thermoplastic resin using a twin screw extruder (100) including, inside a cylinder (10), a screw (50) having kneading discs (60), in which the step of obtaining a resin composition includes an extrusion step of extruding the mixture supplied into the twin screw extruder (100) in an ejection direction under kneading conditions in which X and Y satisfy 4.0≤X in a range of 6.0×10.sup.3≤Y≤7.0×10.sup.4 when a volume-based ejection amount is denoted by X (10.sup.−6.Math.kg.Math.h.sup.−1.Math.mm.sup.−3), and a strain rate is denoted by Y (min.sup.−1).

A multi-shaft extruder which has screw shafts which are rotatable in the same direction and at the same speed, and which has at least one gas venting opening, and which has, in the entry region of said at least one gas venting opening, screw elements with a particularly large pitch or screw elements which have an asymmetric screw profile or which are mounted eccentrically on the axis of rotation of the screw shaft. The invention also relates to the use of the extruder according to the invention for processing or manufacturing plastic materials, and to the use of the screw elements with a particularly large pitch or the use of screw elements which have an asymmetric screw profile or which are mounted eccentrically on the axis of rotation of the screw shaft, in the region of the gas venting opening of a multi-shaft extruder.

The kneading rotor according to one aspect of the present disclosure is a kneading rotor for a kneading machine, comprising a base made of carbon steel or alloy steel for machine structure, a padded layer made of austenitic stainless steel on at least part of a surface of the base and has a hard chromium plated layer on at least part of a surface of the padded layer.

A process for the manufacture of a tread band for pneumatic tyres, wherein the blocks thereof comprise different rubber portions characterized by a different hysteresis loss. The process comprises a shredding step, wherein from a first and from a second rubber tread compound a plurality of fragments is manufactured with dimensions of between 6 and 30 mesh; a mixing step, wherein the fragments from the first and second compound are mixed together in order to obtain a mixture wherein said fragments are distributed in a random manner and retain their chemical/physical individuality; and an extrusion step, wherein the mixture from the preceding step is extruded for the manufacture of the tread band. The first and second compounds have different dynamic properties in terms of: dynamic modulus at 30° C., tand at 0° C., tand at 30° C. and tand at 60° C. The fragments retain a chemical/physical individuality both within the mixture formed during the mixing step and within the tread band formed during the extrusion step.

In the field of mixing rubber mixtures, the invention is directed to a rotor (100) for use in an internal mixer having a mixing vessel in which the rotor rotates, the rotor having one or more blades (104), each blade having a tip (104a) with a profile having a predefined curvature; and an anti-wear device detachably fixed to the tip (104a) of at least one blade, the anti-wear device including a plate (110) with a profile defined by a lower surface (112) with a curvature complementary to that of the tip 104a and an upper surface (114) with a curvature complementary to that of a wall of the vessel to define, between them, a zone of minimum distance that allows passage of the mixture between the plate (110) and the wall of the vessel. The invention is also directed to an internal mixer having at least one mixing vessel in which the disclosed rotor (100) rotates.