DE102008016862A1 - Extruder i.e. two-shaft extruder, has conveyor elements with conveyor sections rotated at angle, where sections comprises axial angle corresponding to maximum of outer dimension of conveyor elements - Google Patents

Abstract

The extruder has a conveyor element (2) and other conveyor elements, which are meshed together in a cross-section perpendicular to three axially parallel shafts. The elements have a conveyor section (3) and other conveyor sections, where the sections are rotated at an angle. The sections have an axial angle corresponding to a maximum of an outer dimension (Da) of the elements, and comprise a maximum length. A central round section is provided between the sections, and possesses a small axial length and a passage height to a housing interior wall (1).

Description

The This invention relates to a two or more shaft extruder according to the preamble of claim 1.

Two- or multi-shaft extruder with corrugated drivable waves point essentially close-meshed screw conveyors as well as mixing, kneading and conveying sections. suitable Components in the required variety are made easier in order to Adaptation of geometry and material to the various process tasks usually designed rotatably attachable to the support shafts.

Around the necessary flexibility with the high demands to reconcile efficiency with safety geometric constraints, such as B. only one or a few Element lengths and / or same mounting position at the ends, necessary. This limits the necessary screw pitches, Element types and / or lengths essential. To the required Adaptability to reach the elements need only the end positions and / or lengths are respected, so the geometric relationships between them, like slope and offset angle, stepless or in stages free according to process engineering Aspects are selectable. Effectiveness and the type of energy transfer from the conveyor structures in the product both product temperature affect during product flow as well as its quality. To powdered solids with viscous substances to moisten and distribute and / or to divide, are shear flows and even better Dehnströmungen in the highly viscous substance to generate.

Out EP 0 002 131 B1 is a self-cleaning extruder with two shafts and two-flighted screw profile described in which a comb and a flight depth of the screw has a small and the second a greater distance from the housing, so that product strands with different constant flight depth arise. US 6,738,270 shows a similar two-shaft extruder with two- and multi-speed conveyor elements of the same or different flight depth. Both known extruders have in common that on a long length a comb interrupts the radial mass transfer, the degree of filling in the delivery channels is different and the axial product flow in the passage remains substantially undisturbed.

The Homogenization and dispersion of the solids in a viscous Matrix, which is achievable with the known extruders leaves but still to be desired. This is especially true for solids with a particle size in the μm range.

task The invention is an unrestricted self-cleaning Multi-shaft extruder to provide, with the Product quality is significantly and effectively improved.

This is inventively with the extruder after the Claim 1 reached. In the subclaims are advantageous Embodiments of the invention reproduced.

According to the invention used at least two-speed conveying elements, in the profile cross section, ie in the vertical cross section to the shaft consist of circular arcs, with intermeshing Conveying elements are mutually substantially around the entire circumference strip tightly. In addition to zweigängigen in particular also used three-speed conveying elements.

there The first gear comb brushes the inside wall of the case with little play off, while between the crest of at least another another aisle and the inner wall of the housing a greater distance exists. Each conveyor element has at least two stepless or staggered steps Conveying sections, wherein preferably each conveyor section has an axial length which is at most the whole, preferably at most half the outer diameter of the conveying element, ie the whole or half inner diameter the housing inner wall corresponds.

In order to Each conveyor section has an angle of 90 ° double-flighted and 60 ° at three-speed one correspondingly large and correspondingly small gangway on. Ie. in the conveying element according to the invention follows a first comb with little clearance to the inside wall of the housing a second comb with a greater distance to the housing inner wall and at an angle to each a correspondingly large passage depth as well as a small gangway after a maximum distance of 1 Da or ½ Da (Da = outer diameter of the conveyor element or inner diameter of the housing inner wall).

This means that across all conveyor channels in the circumferential direction from channel to channel with a multiplication of the flow divisions a large mass transfer is possible, which takes place with different and changing flight depths and corresponding comb / housing games both radially and axially in the same way and thus the Filling level is the same in all channels. Due to the constant geometric baffles in the change of comb and gait in short order in the circumferential and axial direction, a particularly high density of extensional flows is generated. Since this takes place without peak loads and thus without undesirable viscosity drop in all conveying paths in the entire cross section and over the entire length of the conveying element, to achieve a more effective, faster mixing and more uniform homogenization a much higher product quality. This contribute significantly in the transition of the product from one support shaft to the next two sharp deflections in the two-shaft extruder and in particular 12 deflections in a 6-shaft extruder and 24 deflections in a 12-shaft extruder, which further intensifies the effect effective forces in the product.

In order to be about the viscosity of the continuous Phase repeats tensile and bending forces on fatigue strength the solid agglomerates exercised what their endurance break entails. According to the invention therefore a achieved effective homogenization and dispersion of the solid, even with particulate matter having a particle size in the micron range, that is less than 100 microns, in particular less than 10 μm.

With the conveying element according to the invention So the product is constantly changing for a very short time Gutsiefen and fabric speeds and thus stretching processes exposed.

The conveying element according to the invention is preferably integrally formed. While according to the invention of Comb first gear the inner wall of the housing substantially strikes tight, so only a small game of, for example, less as 1, preferably less than 0.5 mm, corresponds to Distance of the comb of the at least one further passage of the screw element from the housing inner wall preferably at most half the first-course corridor, but preferably more than 1 mm.

The Slope of the combs of the conveyor element amounts preferably between 1/3 Da and infinity. Ie. the inventive Conveying element may for example be designed as a kneading block.

The Gang pitch of the conveyor element can of conveyor section be different to conveyor section. Also can be the ratio of the outer diameter Da to the inner or change core diameter Di from conveyor section to conveyor section.

The axial length of the conveying element is preferably at least 1 Da and should not exceed 4 Da, since it is difficult to handle at a length greater than 4 Da, For example, it is difficult to release from the shaft.

The extruder according to the invention preferably has at least three axially parallel waves. The waves can be arranged in a straight, flat surface. Instead, arranged along a circle or circular arc waves may be provided in the cavity of the extruder housing, wherein the extruder housing is provided on the radially inner and outer side of the cavity each with parallel to the extruder axis concave circle segments in which the screw elements are guided substantially tight are, such as in EP-B-0788867 described. In this case, preferably at least six arranged with the same Zentriwinkelabstand waves are arranged in a circle.

With the conveying elements according to the invention can thus a material passage through the ring gear from one side of the cavity to the other. For example, six in Circle with the same Zentriwinkelabstand arranged waves is with twelve deflections of the product homogenizing with it significantly increased.

The Gangtiefe of the first comb of the invention Conveying element may be smaller than the corridor depth of the rest Standard conveying elements of the extruder, ie the conveying elements, with their combs the inner wall of the housing essentially touch tightly. So, for example the conveying element in the material filling zone of Extruders have a particularly large flight depth. For example can the ratio of the outer diameter of the Conveying elements to the inner diameter Di between 1.25 and 2.3. The ratio of the outside diameter the conveying element to the inner diameter is preferably largest in the filling zone of the extruder.

Preferably forms the shaft and the at least one invention Conveyor, which carries them, a single component. Due to the one-piece design of shaft and conveyor element can transmit a much higher torque become. For example, the wave, including the Drive shaft, as well as the conveying element in the region of the filling zone, including the melting zone of a single component consist.

Of the Filling zone can be a zone with a conveying element with a smaller ratio of outer diameter follow the inner diameter, which in turn is a conveying element with a larger ratio of foreign can follow to inner diameter, etc.

below the invention with reference to the accompanying drawings by way of example explained in more detail. Show:

1a and 1b in each case a cross section through a first conveyor section and a second conveyor section of a conveyor element;

2 . 3 and 4 a perspective view and a side view and a longitudinal section of two intermeshing conveyor elements;

5a to 5f in each case a section along the line AA, BB, CC, DD, EE and FF after 3 ;

6 a side view of two intermeshing conveyor elements of a two-shaft extruder;

7 and 8th a side view or a section of two intermeshing conveyor elements with ring sections of a two-shaft extruder; and

9 and 10 a side view or a section of a multi-shaft extruder with arranged on a circle waves.

According to 1a and 1b The housing of the extruder has a cylindrical inner wall 1 on. This is a 2-speed conveyor element 2 used according to 1a and 1b from two conveyor sections 3 and 4 consists.

The profile cross section, ie the vertical cross section to the shaft of the conveyor sections 3 . 4 consists of circular arcs. The arc AB is in 1a or the circular arc A'-B 'in 1b the crest 5 . 5 ' the first corridor again, the inner wall 1 the housing substantially dense, so with little play a 'touches while the circular arc CD or C'-D' the comb 6 . 6 ' represents the second gear, with a distance a to the inner wall 1 is arranged. Thus, according to 1a the one gang with the comb 5 a large corridor b and the second corridor with the ridge 6 a low flight depth c.

The second conveyor section 4 according to 1b that is axially of the first conveyor section 3 follows can by mirroring the first conveyor section 3 on the axis 7 or the axis rotated by 90 ° 8th formed, or be achieved by turning by 180 °.

The axis 7 is formed by the plane that the shaft axis 10 and the middle of the crest 5 cuts, the axis 8th through the plane containing the circular arcs AB and BC in the middle and the shaft axis 10 cuts.

The outer diameter Da of the conveying element 2 can z. B. 10 to 50 mm, the inner diameter Di z. B. 7 to 30 mm, the distance a z. B. 1 to 3 mm. The comb 5 can be an angle α of z. B. 15 to 25 ° include.

Ie. the second comb 6 ' of the second conveyor section 4 , which is formed by the circular arc C'-D 'and the distance a to the housing inner wall 1 is opposite the second comb 6 of the first conveyor section 3 arranged offset by 180 °, as well as the large flight depth b and the low flight depth c.

The intermeshing conveyor elements have an axial distance Ax in a circle, as based on Förderlemente 31 . 32 in 8th illustrates and stretches the whole circumference ( 5a and 8th ).

As in particular from 1a . 1b and 3 visible, the comb touches 5 ' the first gear of a conveyor element 12 the inner wall 1 of the housing as well as the flank 15 and the core 16 of the conveyor element 11 essentially tight, with which it is engaged.

According to 2 are the integral conveyor elements 11 . 12 a two-shaft extruder with internal teeth 13 . 14 provided in order to fix them against rotation on two not shown axially parallel, co-rotating shafts.

Each conveyor element 11 . 12 has an axial length Le of z. B. 2.5 Da, preferably at most 4 Da and consists of six conveyor sections 11a to 11f and 12a to 12f , The conveyor sections 11a to 11f and 12a to 12f each conveyor element 11 respectively. 12 are arranged progressively in stages at the same angle, for example 36 °, with respect to each other. Each promotion section 11a to 11f and 12a to 12f is designed 2-course. Touching conveyor sections touch each other 11a to 11f and 12a to 12f at a point C substantially dense, ie with a small clearance of, for example, less than 1 mm, as from 5a to 5f seen.

As with the conveyor sections 11f and 12f represented here is the crest 5 respectively. 5 ' the first gear of each funding section accordingly 1a and 1b designed to be the inner wall 1 the case touches while in between the comb 6 . 6 ' and the inner wall 1 there is a greater distance a. The axial length Ls of the conveyor sections 11a to 11f and 12a to 12f in each case corresponds to about 1/3 of the diameter Da of the conveying element 11 . 12 , or the diameter of the inner wall 1 of the housing ( 1a and 1b ). Due to the constantly changing course depth according to the combs 5 . 6 and 5 ' . 6 ' the product is constantly exposed to tensile stress. In addition, occurs in the area of the stripping points C a sharp diversion of the product, as in 5b through the arrows 15 illustrated.

After the twin screw 6 have the conveying elements 21 . 22 the conveyor sections 21a to 21e respectively. 22a to 22e on, which are rotated relative to each other by 180 °, that is arranged at an angle offset by 180 °.

To 7 and 8th have the conveying elements 31 . 32 conveyor sections 31a to 31d respectively. 32a to 32d each with a concentric ring 33a to 33d respectively. 34a to 34d on. The conveyor sections 31a to 31d and 32a to 32d are rotated by 180 °. The size H of the annular gap 35 . 35 ' between the rings 33a respectively. 34a and the housing inner wall 1 is between 1/4 and 1/3 of the flight depth, z. B. half of the flight depth ( 8th ).

The axial length La of the rings 33a to 33d . 34a to 34d is at the periphery of a maximum of 1/5 of the length Ls of the conveyor sections 31a to 31d ; 32a to 32d , The Rings 33a to 33d and 34a to 34d need not be exactly centric and circular, but it is sufficient if they are essentially concentric round sections.

In the extruder after 9 and 10 are the conveying elements 41 . 42 . 43 ... rotatably mounted on axis-parallel waves, which are arranged along a circle, wherein the conveying elements 41 . 42 . 43 .... strip each other on the whole circumference. The conveyor elements 41 . 42 . 43 consist of conveyor sections 41a to 41e with a profile offset by 180 °.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 0002131 B1 [0004]
• - US 6738270 [0004]
• EP 0788867 B [0018]

Claims (15)

Extruder having a housing with at least two axially parallel waves which can be driven in the same direction and which are provided with at least two-speed conveying elements ( 2 . 11 . 12 . 21 . 22 . 31 . 32 . 41 . 42 . 43 ...) are provided, wherein in each perpendicular to the waves cross-section meshing conveyor elements ( 2 . 11 . 12 . 21 . 22 . 31 . 32 . 41 . 42 . 43 ...) at the center distance (Ax) with little play on the entire circumference strip, the comb ( 5 . 5 ' ) of the first passage the inner wall ( 1 ) of the housing and the flank and the core of the corresponding conveyor element ( 2 . 11 . 12 . 21 . 22 . 31 . 32 . 41 . 42 . 43 ...) essentially stretches tightly and between the comb ( 6 . 6 ' ) of the at least one further passage and the inner wall ( 1 ) of the housing a distance (a), characterized in that the conveying element ( 2 . 11 . 12 . 21 . 22 . 31 . 32 . 41 . 42 . 43 ...) at least two angularly twisted conveyor sections ( 3 . 4 ; 11a to 11f . 12a to 12f ; 21a to 21e . 22a to 22e ; 31a to 31e . 32a to 32e ; 41a to 41e ), each conveying section ( 3 . 4 ; 11a to 11f . 12a to 12f ; 21a to 21e . 22a to 22e ; 31a to 31e . 32a to 32e ; 41a to 41e ) has an axial length (Ls) at most the outer diameter (Da) of the conveying element ( 2 . 11 . 12 . 21 . 22 . 31 . 32 . 41 . 42 . 43 ...) corresponds. Extruder according to claim 1, characterized in that each conveyor section ( 3 . 4 ; 11a to 11f . 12a to 12f ; 21a to 21e . 22a to 22e ; 31a to 31e . 32a to 32e ; 41a to 41e ) has a maximum length (Ls) of ½ × Da. Extruder according to claim 1 or 2, characterized in that the distance (a) between the comb ( 6 . 6 ' ) of the at least one passage and the inner wall ( 1 ) of the housing corresponds to a maximum of half the flight depth (b) of the first gear. Extruder according to one of the preceding claims, characterized in that the angle of rotation of a conveyor sections ( 3 . 4 ; 11a to 11f . 12a to 12f ; 21a to 21e . 22a to 22e ; 31a to 31e . 32a to 32e ; 41a to 41e ) to the next continuously or in steps up to a maximum of 360 ° / number of turns. Extruder according to one of the preceding claims, characterized in that between the first and the second conveyor section ( 31a . 31b ; 31b . 31c ; 31c . 31d ; 32a . 32b ; 32b . 32c ; 32c . 32d . 32e ) a substantially centric round section ( 33a to 33d ; 34a to 34d ) is provided, which has a small axial length (La) and a free passage height (H) to the housing inner wall which is equal to or greater than half the flight depth. Extruder according to one of the preceding claims, characterized in that the distances, (a) of the further comb ( 6 . 6 ' ) of the housing inner wall ( 1 ) within a conveying element ( 2 . 11 . 12 . 21 . 22 . 31 . 32 . 41 . 42 . 43 ...) are different. Extruder according to one of the preceding claims 1 or 3, characterized in that the pitch of the at least two conveyor sections ( 3 . 4 ; 11a to 11f . 12a to 12f ; 21a to 21e . 22a to 22e ; 31a to 31e . 32a to 32e ; 41a to 41e ) is different. Extruder according to claim 1, characterized in that the axial length (Ls) of the conveying elements (Ls) 2 . 11 . 12 . 21 . 22 . 31 . 32 . 41 . 42 . 43 ...) at most 4 times the outer diameter (Da) of the conveying elements ( 2 . 11 . 12 . 21 . 22 . 31 . 32 . 41 . 42 . 43 ...) corresponds. Extruder according to claim 1, characterized that at least three axially parallel waves are provided. Extruder according to claim 1, characterized that at least six along a circle with the same Zentriwinkelabstand arranged axially parallel waves provided are. Extruder according to claim 1, characterized in that the flight depth (c) of at least one passage of the at least one conveying element ( 2 . 11 . 12 . 21 . 22 . 31 . 32 . 41 . 42 . 43 ...) is smaller than the flight depth of the other conveying elements, which have exclusively corridors with ridges, which touch the inner wall of the housing substantially close. Extruder according to claim 1, characterized in that the ratio of the outer diameter (Da) of the conveying elements ( 2 . 11 . 12 . 21 . 22 . 31 . 32 . 41 . 42 . 43 ...) to the inner diameter (Di) of the conveying elements between 1.25 and 2.3. Extruder according to claim 12, characterized in that the ratio of the outer diameter (Da) of the conveying elements ( 2 . 11 . 12 . 21 . 22 . 31 . 32 . 41 . 42 . 43 ...) to the inner diameter (Di) in the filling zone of the extruder is greatest. Extruder according to claim 1, characterized in that the shaft and the conveying element ( 2 . 11 . 12 . 21 . 22 . 31 . 32 . 41 . 42 . 43 ...) form a component. Extruder according to claim 1, characterized in that the shaft and the at least one conveying element ( 2 . 11 . 12 . 21 . 22 . 31 . 32 . 41 . 42 . 43 ...) form a component in the melting zone of the extruder.