US-12623375-B2 - Multi-shaft preparation unit for plastic melts

US12623375B2US 12623375 B2US12623375 B2US 12623375B2US-12623375-B2

Abstract

A multi-shaft preparation unit for plastic melts, having an extruder housing with an enclosed treatment chamber in its interior, and at least one rotor body shaft mounted rotatably in the treatment chamber and a sealing and guiding body with multiple recesses, in each of which a satellite screw is mounted. The multi-shaft preparation unit has a drive unit in which a gearing unit is arranged outside the extruder housing between a drive motor and the treatment chamber and is connected to the drive shaft sections of the rotor body shaft and of the satellite screws which lead out of the treatment chamber of the extruder housing. A separating device for decoupling a flow of fluid and/or heat emanating from the treatment chamber is provided between the extruder housing and the gearing unit, through which the drive shaft ends of the rotor body shaft and of the satellite screws pass.

Inventors

Stephan Gneuss
Daniel Gneuss
Detlef Gneuss

Assignees

GNEUSS GMBH

Dates

Publication Date: 20260512
Application Date: 20230512
Priority Date: 20201113

Claims (9)

1 . A multi-shaft preparation unit for plastic melts, the multi-shaft preparation unit comprising: an extruder housing that has an enclosed treatment chamber for plastic melts in an interior thereof, and has at least one rotor body shaft mounted rotatably in the treatment chamber with at least two receiving grooves, in each of which a satellite screw is mounted; a drive unit in which outside the extruder housing, between a drive motor and the treatment chamber, a gearing unit is arranged, which is connected to drive shaft sections of the rotor body shaft and the satellite screws led out of the treatment chamber of the extruder housing; and a separating device arranged between the extruder housing and the gearing unit, the separating device provided for decoupling a flow of fluid and/or heat emanating from the treatment chamber, through which the respective drive shaft sections of the rotor body shaft and the satellite screws pass, wherein the drive shaft sections of the rotor body shaft and the satellite screws pass through at least one cavity in the separating device, and wherein the drive shaft ends of the rotor body shaft and the satellite screws are each guided through holes in a sealing and guide body on the rotor body shaft, which sealing and guide body closes off the rear part of the treatment chamber.
2 . The multi-shaft preparation unit according to claim 1 , wherein at an end of the extruder housing facing the cavity and/or in a wall of the separating device, at least one temperature control channel is formed, which is flowable by a temperature control fluid.
3 . The multi-shaft preparation unit according to claim 1 , wherein the drive shaft sections of the satellite screws in the cavity are each divided into two sections, each of which is connected to each other via a coupling element.
4 . The multi-shaft preparation unit according to claim 3 , wherein the coupling elements are designed as a metal bellows coupling.
5 . The multi-shaft preparation unit according to claim 1 , wherein the drive shaft sections of the satellite screws are provided with a return thread at least over a portion of their length section located in the respective holes of the sealing and guide body.
6 . The multi-shaft preparation unit according to claim 1 , wherein sealing and guide bodies on the rotor body shaft are provided with a return thread at least over a portion of their length.
7 . The multi-shaft preparation unit according to claim 1 , wherein the rotor body shaft is connected to a gearing rotor body of the gearing unit and the drive shaft sections of the satellite screws are mounted rotatably in the gearing rotor body, and wherein the satellite screws, in each case provided with a pinion on their end side, engage solely in a fixed internal annular gear which surrounds the gearing rotor body.
8 . The multi-shaft preparation unit according to claim 1 , wherein on the extruder housing, a downward-pointing discharge housing opening is provided.
9 . The multi-shaft preparation unit according to claim 1 , wherein on the housing of the multi-shaft preparation unit, at least one suction housing opening is provided, to which a vacuum pump is connected, and wherein the one suction housing opening or multiple suction housing openings together extend over at least 75% of the axial length of the treatment chamber.

Description

This nonprovisional application is a continuation of International Application No PCT/DE2021/100906, which was filed on Nov. 12, 2021, and which claims priority to German Patent Application No 10 2020 130 080.8, which was filed in Germany on Nov. 13, 2020, and which are both herein incorporated by reference. BACKGROUND OF THE INVENTION Field of the Invention The invention relates to a multi-shaft preparation unit for plastic melts. Description of the Background Art For the treatment of plastic melts, in particular polyester, a multi-shaft preparation unit in the form of a so-called Multi Rotation System (MRS), which is fundamentally described in WO 2003 033 240 A1 (which corresponds to US 2005/0047267, which is incorporated herein by reference), has proven to be successful. It contains an extruder screw, which comprises a so-called polyrotation unit with a rotor body shaft between a feed and metering zone for drawing in and melting the plastic, and a discharge zone. The latter has a significantly larger diameter as compared to the other zones and also several rotating satellite screws. With the multi rotation system, a significant increase in degassing performance is achieved as compared to single and twin screw systems. Consequently, the residence time of the melt in the polyrotation unit can be kept very short. The degree of filling, i.e., the proportion of the volume taken up in the operation of plastic melts in relation to the total free volume in the treatment chamber in which the rotor body shaft rotates with the satellite screws, is specified by design by the coordination of diameters and pitches of the screws and is optimized for a specific application. A change of the filling degree as well as the residence time is possible during operation at best to a limited extent. In addition, the well-known drive concept provides for a drive zone for the satellite screws, which is located within the treatment chamber intended for degassing. The melt transferred from the metering zone is passed through the drive zone. On the one hand, the energy input taking place via the shearing occurring there can be advantageous because it favors the homogenization of the plastic melts. On the other hand, a high drive power is required to drive the extruder screw, which is already very long with several zones in a row, from its end together with the satellite screws. The treatment of highly viscous plastic melts in such a multi rotation system therefore has limits. A multi-shaft preparation unit described in CN 101 293 397 A does not have an external gearing. All gears are located directly in the medium that is conveyed and treated in the preparation unit. This means that no thermal decoupling is possible. In addition, the shearing to which the plastic is exposed in the drive zone with the gears has a negative effect on plastic melts. Furthermore, the treatment chamber opens so far in the direction of the drive that the rotating sealing ring is exposed to the hot plastic melts. A multi-shaft extruder according to DE 10 2006 052 610 A1, which corresponds to US 2010/0067320, has satellite screws which are fixed but are not part of a rotating unit. The preparation unit and the gearing unit are separated from each other. However, this does not have a cooling purpose. Cooling should take place solely via cooling channels. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a multi-shaft preparation unit for plastic melts of the type mentioned above so that in particular also highly viscous plastic melts are easy to process. The solution according to the present invention includes a multi-shaft preparation. According to an exemplary embodiment of the invention, the melt is fed from an outsourced melting extruder into the treatment chamber, so that the rotor body shaft as the main rotor shaft, which carries the rotor body in which the satellite screws are mounted, has no feed and metering zone. The invention provides an external drive for the multi-shaft preparation unit, in which drive both the central rotor body shaft and each individual satellite screw have an extended rear shaft end, which is led out of the treatment chamber. Between an extruder housing enclosing the treatment chamber and a gearing unit arranged outside of it, a separating device is provided with or in which possible negative influences on the gearing can be reduced or even compensated: Material flows in the form of leakage flows escaping from the extruder housing are interrupted in the separating device, so that contamination of the gearing with plastic melts is excluded even in the event of a malfunction in which pressure builds up in the treatment chamber. Alignment errors between the bearing of the respective front shaft ends in the extruder housing and in the gearing can be compensated by couplings arranged in the separating device. This also applies in the event that the satellite screws do not have a front bearing in