How does extruder drive work?
These objects are achieved, in accordance with the invention in an extruder drive assembly having a housing, at least two extrusion worms each having a drive shaft extending into the housing, and at least one drive motor including at least one cylindrical stator fixed in the housing and a cylindrical rotor cooperating with the stator so as to be rotatably driven by the stator. The rotor surrounds the drive shafts that are each independently connected to the rotor for driving thereby and are not directly connected with each other.
According to a feature of the invention, the single screw extruder drive comprises a drive housing and at least one drive motor with a stator and rotor. Each of the two extruder worms has a connecting shaft at least partly encompassed within the drive housing. In the drive housing there is at least one cylindrical stator and this stator surrounds a cylindrical rotor. The two extruder worms with their connecting shafts are independently connected with the rotor, but out of direct contact with each other. As has already been indicated in the preferred embodiment, the apparatus is a double-worm extruder.
According to a preferred embodiment of sheet production extruder stator is mounted in the drive housing and surrounds a single cylindrical rotor that in turn is connected with both of the connecting shafts of the two extruder screws or worms. It is possible in accordance with the invention that the rotor is directly connected to one shaft or at least one shaft, i.e. without the interposition of further elements.
In a highly preferred embodiment, the single rotor is internally toothed and each of the shafts is formed like a gear with external toothing, usually in the form of a pinion. In this embodiment, the outer gear teeth of the rotor, which is thus a ring gear, mesh directly with at least one of the pinions and thus form a direct transmission link therebetween. The pinions of both shafts can mesh directly with the teeth of the ring gear, namely, the rotor. In this manner a synchronous drive of the worms in the same sense is effective.
In a second embodiment of the invention, twin screw extruder of one of the worms meshes directly with the gear teeth of the rotor and the gear of the other worm is connected to the rotor via an intervening direction-changing gear. In this case, the worms are driven synchronously in opposite senses. It has been found to be advantageous to use only a single intervening gear and thereby achieve the opposite sense rotation of the worm.