Abstract: Impure hexamethylenediamines and more particularly those hexamethylenediamines containing contaminating amounts of tetrahydroazepine (THA), or more generally contaminating amounts of imines, are purified by distillation carried out with a short retention time of the impure hexamethylenediamine in the distillation column; the hexamethylenediamine obtained has a very low concentration of THA.

Abstract: Impure hexamethylenediamines and more particularly those hexamethylenediamines containing contaminating amounts of tetrahydroazepine (THA), or more generally contaminating amounts of imines, are purified by distillation carried out with a short retention time of the impure hexamethylenediamine in the distillation column; the hexamethylenediamine obtained has a very low concentration of THA.

Abstract: Apparatus for mounting and removing screws of an extrusion machine comprising two screws (10a, 10b) driven in rotation and guided at each of their ends by a bearing (1, 2). The screw-bearing assembly is placed on a work table (20) provided with adjustable devices (25, 26, 28) for supporting the screws, removing the bearings (1, 2) are removed and the sections (12) are successively extracted by means of suitable tooling and a section-hoisting device with respect to each screw separately. By means of a double section-hoisting device, a new section (12) is then simultaneously mounted on each splined shaft (11a, 11b) and the operation is repeated for each pair of new sections, placing back in position the bearing (1, 2) corresponding to each end of the shafts (11a, 11b) and lastly remounting the screw-bearing assembly in the extrusion machine.

Abstract: Method for mounting and removing screws of an extrusion machine comprising two screws (10a, 10b) driven in rotation and guided at each of their ends by a bearing (1, 2). The screw-bearing assembly is placed on a work table (20) provided with adjustable devices (25, 26, 28) for supporting the screws, removing the bearings (1, 2) are removed and the sections (12) are successively extracted by means of suitable tooling and a section-hoisting device with respect to each screw separately. By means of a double section-hoisting device, a new section (12) is then simultaneously mounted on each splined shaft (11a, 11b) and the operation is repeated for each pair of new sections, placing back in position the bearing (1, 2) corresponding to each end of the shafts (11a, 11b) and lastly remounting the screw-bearing assembly in the extrusion machine.

Abstract: A screw element for use in a material-processing machine comprising at least one screw formed by a central driving shaft (2) on which are mounted a plurality of hollow elements (12, 13 . . . ) provided on their inner wall with grooves (31) engaging with corresponding splines (21) of the central shaft (2). A cylindrical inner collar (3) made from a product resistant to the mechanical driving stresses and on the inner wall (32) of which are formed the grooves (31) corresponding to the splines (21) of the shaft, and an outer collar (4) made from a product resistant to the abrasion of the processed material and on which are formed, within the body of the outer collar, helical threads (42) or other peripheral material-processing means, the outer collar (4) being mounted without clearance on the inner collar (3) and being connected to the inner collar for rotation therewith. The invention is applicable in particular to the construction of extruding machines.