EP1945437A1

EP1945437A1 - Multi-screw extruder

Info

Publication number: EP1945437A1
Application number: EP06806206A
Authority: EP
Inventors: Josef A. Blach
Original assignee: Blach Verwaltungs GmbH and Co KG
Current assignee: Blach Verwaltungs GmbH and Co KG
Priority date: 2005-11-11
Filing date: 2006-10-12
Publication date: 2008-07-23
Also published as: CN101300120B; BRPI0618511A2; DE102005053907B4; US8172450B2; US20090274003A1; RU2008123594A; CN101300120A; RU2382701C1; JP2009514704A; DE102005053907A1; WO2007054173A1; JP5000661B2; KR20080066767A

Abstract

In an extruder in which the push-on elements (1) have a cross-sectional profile which comprises arcs of a circle that correspond to the maximum diameter of the push-on element, the core diameter of the push-on element and the axial spacing of the push-on elements (1), the push-on element (1) does not have any shaft-hub connection in the region of the arc that corresponds to the core diameter of the push-on element and/or it is provided with reinforcing segments (13, 14) at its ends.

Description

Multi-screw extruder

The invention relates to an extruder with at least two support shafts according to the preamble of claim 1.

For non-rotatable connection of the support shaft with the screws or the like Aufsteckelementen different shaft-hub connections are known.

Thus, from DE-PS 813 154 a machine with two shafts, in which a key or a square profile is used as a shaft-hub connection. According to DE 77 01 692 Ul a splined shaft is used as a shaft-hub connection with integrated wedge, while DE 27 50 767 Al and EP 0 001 970 Al round shafts with three separate insertion wedges at the same pitch angle and EP 0 330 308 Al two wedges with Describe unequal pitch angle. Nowadays, however, especially the involute profile shaft according to DIN 5480 is used.

Furthermore, in "Design Books", Springer-Verlag, 1984, pages 210 and 211, a variety of positive shaft-hub connections with immediate and indirect positive fit taking into account the fundamental for the design of the machine Kerbwirkungszahlen and fatigue strength described and compared In these cases, however, the hub has a constant wall thickness Extruder of the type specified in the preamble of claim 1, in which the worm or the like Aufsteckelemente meshing around the entire circumference, the Achsschnittprofil the Aufsteckelements is determined by three circular arc corresponding to the Schneckenaußendurchπiesser, the Schneckenkerndurchmesser and the axial distance of the waves (see. EP 0 002 131 B1).

The most economical worm shaft is that with the largest delivery volume and at the same time the highest, introductory torque. The overall cross section of a Forderschneckensystems is limited by the diameter of Gehausebohrung and the distance between adjacent Gehausebohrungen. It must be distributed proportionately to the technical requirements and possibilities as well as the need for four cross sections. For transporting the product, first the free surface of the conveyor is determined, which is determined by the outside diameter of the screw element and the passage depth. Thus, the core diameter of the screw element and the center distance to the adjacent support shaft is fixed. Secondly, the support shaft requires the computationally usable surface portion for axial guidance of the required shaft torque for the subsequent attachment elements. Third, the constructive need for flat space for the acquisition of the proportionate torque for the slip-on element must be taken into account, and fourth, the remaining cross-sectional area of the slip-on element remains relatively to the shaft torque for a reliable slip-on element.

On each support shaft, which generally has a length which corresponds to at least twenty times the housing bore diameter, a plurality of Aufsteckelementen are plugged tight. The highest possible torque on the the largest arithmetically usable shaft diameter dTi can be transmitted, determines the decisive economic use of the extruder.

The performance and economy of an extruder is therefore determined by the highest permissible torque in the long term while maintaining the highest volume performance of the extruder.

In "Kunststoffe" 2/2005, page 75, it is described that the performance-limiting machine element of a twin-screw extruder is primarily the screw core diameter: the deeper the screw elements are cut, ie the greater the free volume of the screw elements, the smaller the remaining cross-section For the screw core diameter and the associated shaft-hub connection, the problem of the DIN or a similar profile in the Zahnfußfestigkeit is seen, so that an asymmetric toothing for better force application and stress distribution is proposed.Apart from the costly production of asymmetric teeth the performance of this extruder even further increase.

The object of the invention is to substantially increase the volume performance of an extruder at the same torque.

This is inventively achieved with the characterized in claim 1 extruder. In the dependent claims advantageous embodiments of the invention are shown.

According to the invention, the passage depth of the Forder- or the like Aufsteckelements is increased at high torque transmission of the shaft-hub Verbmdung. That is, at the same large center distance of the slip-on outer diameter is greater and the Aufsteckelementkerndurchmesser reduced by the same amount, which significantly increases the free Forderflache the Forderelement or working surface of the working element and thus the performance of the extruder.

For this purpose, the Aufsteckelement whose cross section is composed according to the preamble of claim 1 of three circular arc, (1) in the region of the circular arc which corresponds to the Aufsteckele- mentkerndurchmesser formed without shaft-hub connection under flat contact with the support shaft and / or (2) provided with Verstarkungssegmenten at its ends.

In the region of the circular arc, which corresponds to the Aufsteckelementkerndurchmesser, the plug-on element has the lowest wall thickness. When the shaft transmits torque, it tightens more than the slip-on elements, which are harder and more torsionally rigid than the shaft. Therefore, the slip-on element absorbs this force in the respective region of the shaft. In this power transmission, the ends are exposed to the smallest thickness of the Aufsteckelements the strongest load.

In other words, it is necessary to at least maintain a minimum wall thickness of the attachment element in the region of the circular arc with the attachment core diameter.

This is achieved in the invention in that no power transmission of the shaft-hub connection is provided in this area. Thus, the cross-sectional area, which otherwise occupies the shaft-hub connection in this area, added to the cross-sectional area of the slip-on in this area and thus the flight depth can be increased accordingly, without affecting the strength of the support shaft. Since the usable shaft diameter dTi does not change, no reduction of the transmittable torque occurs.

A support shaft designed in accordance with the invention can be produced in a simple manner by removing from a conventional support shaft, e.g. an involute profile shaft as in DIN 5480, in the region where the plug-in element bears with its corresponding to the arc of the Aufsteckelementkerndurchmessers, thinnest region, the toothing of the shaft, for. removed by grinding.

The surface with which the support shaft and the slip-on element abuts in the region of the slip-on element with the circular arc corresponding to the slip-on core diameter can be a curved arcuate surface or a flat surface, ie a surface corresponding in cross-section to a straight line.

In addition, and with male slip-on elements, the slip-on element can be reinforced at its ends by preferably annular reinforcing segments in order to accommodate the high forces occurring in the torque transmission occurring at the ends of the slip-on element.

Although the product flow is slowed down by the reinforcing segments, this effect is partial and so slight that it plays no role in practice.

As calculations and tests have shown, with the erfmdungsgemaßen extruder at the same torque, the volume performance can be increased by about 30%. In addition, according to the invention, the sealing surface is increased, which prevents material between the plug-in elements and the shaft can penetrate and crack.

Preferably, in the extruder according to the invention, the shaft-hub connection is formed by an involute profile, serrated or splined connection. In particular, compounds have proven to be suitable in which the keyways in the slip-on and the teeth of the shaft are rounded.

The inventive extruder has at least two support shafts, but it may also have a significantly larger number of support shafts. Thus, for example, the extruder may have at least three shafts arranged in a cavity of an extruder housing along a circle or circular arc with the same central angular spacing, parallel to the extruder axis, the extruder housing being provided on the radially inner and outer side of the cavity with concave circular segments parallel to the extruder axis, where the plug-in elements are guided. The cavity may also be annular. Such an extruder is e.g. in EP 0 788 867 B.

The conveyor attachment element is in particular formed by a screw element, the working attachment element e.g. by a requesting screw element opposite slope direction, a kneading block a blister or a toothed disc. Also Aufsteckelemente may be provided which have a Forder- and a working section.

The invention is explained in more detail by way of example with reference to the accompanying drawings. Show: Figure 1 shows the front profile of two circumferentially closely intermeshing screw elements in a twin-screw extruder;

Figure 2 and 3 is a side view and end view of a Aufsteckelements according to a first embodiment;

Figure 4 and 5 is a perspective view and a

End view of a slip-on element according to a second embodiment; and

Figure 6, 7 and 8 is a side view, end view and a perspective view of a Aufsteckelements according to a third embodiment.

As shown in Figure 1, have two interlocking Aufsteckelemente 1 on a front or cross-sectional profile surface 2, which is bounded by circular arc A-B, E-F and A-E. The circular arc A-B has a diameter corresponding to the maximum Aufsteckelementdurchmesser DA, the circular arc E-F a diameter corresponding to the Aufsteckelement- core diameter Dk, and the circular arc A-E a diameter whose radius corresponds to the axial distance Ax of the two combined Aufsteckelemente 1 maximum.

The slip-on element 1 has an internal toothing 3, in which the support shaft 4 engages with its external toothing 5. The slip-on element thus has a free Forderflache 6, which is determined by the diameter DA and the flight depth. Furthermore, the area fraction 7 is required for the shaft-hub connection, which results from dTA and dTi. According to Figure 2 and 3, the formed as a screw element Aufsteckelement 1 also has an internal toothing 3, in which the support shaft 4 engages with its outer toothing 5 all around. In this case, an involute profile toothing is provided. At the two ends of the slip-on element 1, an annular reinforcing segment 8, 9 is provided at each end.

In the embodiment according to FIGS. 4 and 5, the two-pronged plug-in element 1 is formed in the thin region 11, 12 without shaft-hub connection corresponding to the circular arc E-F. That is, both the slip-on element 1 and the support shaft 4 are smooth in the sector corresponding to the circular arc E-F and are in full-flat contact with each other. The splines of the involute 3 extend so that at the ends only in the thick-walled areas of the slip-on 1, which correspond to the circular arc A-E and A-B. That is, the areas 11 and 12 are not weakened by keyways at the ends. In this case, the teeth 3 on both sides of the thin regions 11, 12, ie in the areas opposite the circular arc A-B areas, each have four teeth, with five wedges of the support shaft 4 engage in each of the two teeth 3. That the torque transmission takes place with two groups of four teeth and five wedges, the distance from one group to another being greater than that from tooth to tooth or wedge to wedge of a group.

In the embodiment according to FIGS. 6 to 8, the regions of the male plug-in element without shaft-hub connection corresponding to the circular arc EF are formed, and reinforcing rings 13, 14 are also provided at the ends, wherein the reinforcing rings 13, 14 are formed as concentric rings , In addition, the shaft-hub Compound formed concentric to the axis of the support shaft, as shown in Figure 4 and 5. The support shaft 4 is designed so that the smooth areas formed by the slip-on 1 correspond to this.

Claims

claims

1. extruder with at least two axis-parallel support shafts (4) on which formed as conveying and / or working elements Aufsteckelemente (1) are fitted against rotation by a shaft-hub connection with which adjacent shafts (4) intermesh, at least one Part of the Aufsteckelemente (1) has a cross-sectional profile (2) consisting of circular arcs (AB, EF and AE), the maximum Aufsteckelementdurchmesser (D), the Aufsteckelementkerndurchmesser (d) and at most the axial distance (Ax) of the Aufsteckelemente (1) correspond, characterized in that the Aufsteckelement (1) in the region of the circular arc (EF), which corresponds to the Aufsteckelementkerndurchmesser (d) without torque transmission of the shaft-hub connection under surface or partial contact with the support shaft (4) is formed, and that for torque transmission two groups of at least two wedges or teeth are provided, wherein the distance from group to group gr SSSR than the number of teeth.

2. Extruder according to claim 1, characterized in that each of the two groups has at least three teeth.

3. Extruder according to claim 1 or 2, characterized in that the slip-on element (1) in the area without shaft Hub connection in the form of a circular arc or a straight line on the support shaft (4) flat or partial surface rests.

4. Extruder according to claim 1, characterized in that the reinforcing segment (8, 9, 13, 14) is annular.

5. Extruder according to claim 4, characterized in that the reinforcing segment as a concentric ring (8, 9) or as a cam-shaped expanding ring (13, 14) is formed.

6. Extruder according to claim 1, characterized in that the shaft-hub connection is an involute profile, serrated or splined connection.

7. An extruder according to claim 1, characterized in that the conveying elements are formed by screw conveyor elements and the working elements by screw elements opposite slope direction, kneading blocks, blisters or toothed discs.

8. An extruder according to claim 1, characterized in that a multi-splined shaft connection is provided for torque transmission, which is only partially effective on the circumference.

9. Extruder according to claim 1, characterized in that the reinforcing segment (8, 9, 13, 14) is designed with a diameter which is greater than the Aufsteck- element core diameter (Dk) and at most the axial distance (Ax) corresponds.