Abstract:
The invention concerns endless screw elements for a twin-screw extruder having shafts rotating in the same direction whereon are mounted said screw elements with closely interlaced outer profile. Said screw elements enable fibres, in particular natural fibres, to be smoothly incorporated in a molten synthetic mass and a maximum fibre length to be maintained. Therefor, a plurality of structural elements (54) is arranged at the surface of the screw elements (60), said structural elements not projecting relative to the outer profile of the screw elements.
Abstract:
An apparatus for injection molding two compatible polymeric materials, in which two or more plasticizing zones (40, 42) on a screw (26) are used to simultaneously or sequentially plasticize the two materials into a common accumulation space (48) through separate passageways. The charge comprising multiple layers of material is then injected into a closed mold by means of forward axial motion of the screw with respect to its enclosing barrel (10). Once inside the mold, the first material forms a skin layer, totally or partially surrounding the other material. In this way a part having a plurality of material properties may be produced in a single operation.
Abstract:
The invention relates to a screw element with an external radius Ra and a core radius Ri, for multi-screw extruders with mutually-sweeping screw shafts rotating in the same sense, in particular for double screw extruders, which have a profile in the axial cross-section through the longitudinal axis thereof, which has just one screw land (1, 1'), corresponding to a conventional simple screw for mutually-sweeping screw shafts, on each of both axial faces (front face 8, rear face 8'). The width (sweep angle j) of the screw land (1) and conversely the width (sweep angle j) of the screw land (1') are embodied in a particular manner and a shear land (7) with constant shear land radius Rs, which is greater than Ri and smaller than Ra is provided.
Abstract:
A screw extruder, including a barrel having a bore which defines an inner surface. At least one extruder screw (28) is positioned within the bore, each screw (28) further including a central shaft (34) and at least one screw flight (30). Each screw flight (30) further includes a front pushing face (36) and a rear face (38). The profile (40) of each front pushing face (36) acts with the inner surface of the barrel to form a progressively narrowing passage through which material is forced into multiple regions of high elongational and shear stress which act to break down agglomerates of material and thus dispersively mix the material.
Abstract:
Procédé de revêtement de la paroi sommitale (7) d'au moins une partie en relief (4) d'une vis d'extrusion (1) comportant les étapes suivantes :
on dépose sur et au voisinage d'au moins une arête (8, 9) de la partie sommitale de chaque partie en relief (4) à revêtir, un cordon métallique de dureté D1, ledit cordon occupant une fraction seulement de la largeur de ladite partie sommitale; on dépose ensuite sur le reste de la partie sommitale non revêtue, un deuxième matériau de dureté D2, ladite dureté D2 étant strictement différente de la dureté D1; on rectifie les dépôts réalisés aux étapes précédentes de façon à obtenir le profil et les cotes de chaque partie en relief (4) sur la vis (1).
Abstract:
A fiber reinforced thermoplastic resin structure comprising a thermoplastic resin and reinforcing fibers, having a ratio (Lw/Ln) of the number average fiber length (Ln) to the weight average fiber length (Lw) of the uniformly dispersed reinforcing fibers of 1.1 to 5, and having a weight average fiber length of 1.0 mm to 200 mm as well as a process and extruder for the production thereof.
Abstract:
A machine for processing solid and viscous plastic materials includes a screw element (32) having a shearing flight (90) and a scraping flight (75). Upon rotation of the screw, the shearing flight (90) shears the plastic material (89) and the scraping flight (75) guides the material (89) to the shearing flight (90). Preferably, the screw includes a plurality of threads which extend from one end of the screw to the other, and which include a plurality of shearing and scraping flights.