Abstract: An apparatus for reducing wastage during the start-up phase of extrusion device used to produce extruded profiles such as tread strips for vehicle tires from a plurality of mixtures. Each of a plurality of extruders extrudes one component of the profile and is provided with its own drive motor. The outlets from the extruders communicate with a template member having flow channels formed therein which communicate with the outlet ends of the extruders and which lead into a common extrusion port. Pressure sensors are positioned adjacent to the outlet of each extruder. These pressure sensors and the drive motors for each extruder are operatively connected to a control device which has stored therein predetermined desired pressure levels for each extruder. The drive motors for the several extruders are actuated and the pressure of each is monitored and compared with the predetermined desired pressure for each extruder.

Abstract: A method of reducing wastage during the start-up phase of an extrusion device used to produce extruded profiles such as tread strips for vehicle tires from a plurality of mixtures is disclosed. The extrusion device comprises a plurality of extruders each extruding a component of the profile and each extruder has its own drive means. The outlets from the extruders communicate with a template member having flow channels formed therein which lead into a common extrusion port. The drive means are actuated simultaneously and the pressure of each of the components is monitored in the outlet region of each extruder. These pressures are compared with a pre-determined desired pressure by a control device, which device switches-off the appropriate drive means as each desired pressure is attained. When all desired pressures have been attained, all of the drive means are re-actuated simultaneously by the control device.

Abstract: An extrusion head for producing, for example, tread strips for vehicle tires comprises a stationary central portion and two pivotable outer portions. Between each outer portion and the central portion, in the operative position of the head, insert members are interposed. Flow channels for the different materials used to make the tread strip and defined between the insert members and the central and outer portions of the head. The insert members are made displaceable by being detachably affixed to push-rods which are hydraulically, pneumatically or mechanically actuated. This provides for movement of the insert members, when the outer portions are pivoted away from the central portion, into a position which permits unhindered access to all sides of the insert members and permits the rapid cleaning and/or replacement thereof.

Abstract: An extrusion head for producing flat profiles such as tread strips for automotive vehicles from three or more different rubber or plastics materials is disclosed. The head comprises a fixed central portion and upper and lower portions pivotally connected thereto, and is fed with the different mixtures by a plurality of screw or worm extrusion devices. Between the upper and central portion and the central and lower portions of the head, insert members are located. In the upper and/or lower surface of each insert member, flow channels for the mixtures are defined, the flow channels each being bounded upwardly or downwardly as appropriate, by a plane surface of one of the portions of the head. The insert members are axially divided and are made in one piece. The flow channels each have a longitudinal axis of symmetry and such axes lie in a common vertical plane.

Abstract: In a screw extrusion device used for extruding plastics materials, a filter or tool-carrier is disposed at the downstream or outlet end of the extruder, an annular pressure element bearing on the carrier so as to secure and seal the carrier in its operative position. The carrier is displaceable perpendicularly to the flowpath of the plastics material so as to permit facile changing of the filter element. The annular pressure element is acted upon by hydraulic fluid, the hydraulic circuit including an annular pressure chamber. The inner and outer walls of the chamber are formed, respectively, by concentric metal bellows. One end of each bellows is mounted on the pressure element and the other end thereof on a housing.

Abstract: A power branching transmission, having two parallel output shafts, each of which carries a rotationally rigidly connected ouptput drive pinion, the output drive pinions being axially offset with respect to one another and each meshing with a respective rotatable ring gear and with a respective central gear wheel disposed in the respective ring gear, a pair of driving pinions rotationally rigidly disposed on parallel drive shafts and each meshing with a respective one of the ring gears and a respective one of the central gear wheels, each of the ring gears and each of the central gear wheels having at least one coaxial race with at least one supporting roller disposed between the races and bracing the respective ring gear and associated central wheel with respect to one another. No housing is required, tooth forces of the ring gears and central gears being accommodated by the supporting rollers and not transmitted to the radial bearings of the input end output shafts.

Abstract: A twin screw extruder comprising a cylinder having twin bores therein to receive the twin screw of the extruder and a circular casing with at least one passage to permit heating or cooling fluid to flow between the cylinder and the casing, in which the cylinder has a generally circular outside contour with a first set of grooves and a second set of grooves forming parts of said at least one passage, extending obliquely to the longitudinal axis of the cylinder and formed in the outer surface of the cylinder, the bottom walls of the grooves extending parallel to a plane which includes the two longitudinal axes of the twin bores with the first set of grooves lying on one side of said plane, and the second set of grooves lying on the other side of said plane, the inclination of said first set of grooves to said axis being opposite to the inclination of said second set of grooves to said axis, and the inside of the casing containing spaced recesses forming further parts of said at least one passage and, except for