The invention relates to a multi-spindle kneading mixer with at least two axis-parallel agitator shafts engaging into one another, one of which is designed as a disk shaft, into which kneading elements of a kneading shaft engage, wherein these kneading elements scrape the product off from the disk surfaces and press it by means of corresponding diverting surfaces into a kneading gap formed on the one hand by the kneading element and on the other hand by the opposite disk surface, the product being moved axially to and from between the disk surfaces.

The invention relates to a kneading mixer for performing mechanical, 
chemical and thermal processes, with at least two axis-parallel rotating 
shafts, disk elements with approximately axially aligned kneading bars 
fastened to them being arranged on one shaft and kneading elements being 
arranged on the other shaft, and the disk elements and kneading elements 
engaging into one another. 
A multi-spindle mixing and kneading machine is known from Swiss Patent 
Specification No. 506,322, one shaft of this being equipped with radial 
disk elements and axially aligned kneading bars which are arranged between 
the disks (disk shaft) and into which engage frame-like kneading elements 
arranged on a second parallel agitator shaft (kneading shaft) and cleaning 
the disks and kneading bars of the disk shaft. The shearing forces and 
mixing movements exerted on the processed product by these kneading 
elements on the kneading shaft, in interaction with the disks and kneading 
bars of the disk shaft, have proved highly effective for a macro-mixing 
effect, but are often insufficient or very time-consuming for the 
micro-kneading effect which, in many products, is necessary for breaking 
down the agglomerates. 
The present invention affords a significant improvement of the 
micro-kneading effect and consequently a substantial broadening of the 
scope of use.

The construction of the kneading mixer is illustrated in FIGS. 1 and 2, 
portions being shown with a cutaway housing for a clearer representation 
of the agitators. 
In conformity with the two agitator shafts engaging into one another, the 
housing has the cross-sectional form of a FIG. 8, as is evident from FIGS. 
5 to 7. The housing is composed of the housing parts 2 and 3 and the 
outflow housing 4 which are screwed together by means of flanges. On each 
of its end faces, it is closed off by means of the end walls 5 and 6 which 
adjoin the louvers 7 and 8 with the agitator-shaft bearings 9, 10 and 11, 
12. The passage of the agitator-shaft journals through the end walls is 
equipped with glands 13 of a known type. The kneading mixer is supported 
by means of the feet 14. 15 denotes a gear which couples the two shafts 22 
and 29 to one another in the desired speed ratio. The drive-shaft journal 
16 can itself be driven in any way from a gear and a drive unit. 17 
denotes the feed connection for the product which leaves the machine at 
the outflow connection 18. 19 denotes a connection for drawing off gases 
and vapors, while 20 designates the various connections for emptying the 
machine. 
For a clear illustration of the working principle, all the Figures and the 
description show a version in which the driven kneading shaft of higher 
speed rotates four times faster than the disk shaft driven via the gear 
15. Of course, it is also easily possible to provide other expedient 
ratios between the two shafts. 
The first shaft or disk shaft 22 comprises a central tube 23 with laterally 
attached shaft journals 24 and 25 which are supported in the bearings 10 
and 12. The central tube 23 carries, in radial planes, the disk elements 
26 which are connected to one another on the outer diameter by means of 
the kneading bars 27. These kneading bars 27, but often also the disk 
elements 26, are arranged on helices for the purpose of more efficient 
transport of the product through the machine. If a longer retention-time 
range is desired for the process, individual kneading bars can also be 
arranged at an inclination for the purpose of return transport. The 
kneading elements arranged on the kneading shaft 29 mesh with the kneading 
bars 27 of this disk shaft. The kneading shaft 29 comprises a central tube 
30, into which are inserted the shaft journals 31 and 32 supported in the 
bearings 9 and 11. The kneading elements 34 are arranged on the central 
tube 30, likewise usually on a helix, and are each composed of the radial 
parts 35 and 36 and of the kneading bar 37 connecting these two radial 
elements. 
A level plate 21 which regulates the filling of the machine in the manner 
of an overflow weir is inserted between the housing part 3 and the outflow 
part 4. 
The product fed to the kneading mixer in the connection 17 is picked up as 
a result of the inclination of the kneading bars 27, 37 on the two 
agitator shafts and is transported towards the outflow housing. After 
spilling over the level plate 21, the product falls into the outflow 
housing 4 and is discharged there through the connection 18. 
The cycle of movement can be seen in its simplest form in FIG. 3. During 
one revolution of the disk shaft 23, the kneading elements 34 of the 
kneading shaft 29 engage four times into the disk elements 26 of the disk 
shaft, the kneading bars 37 of the kneading shaft also meshing 
respectively with the kneading bars 27 of the disk shaft and thereby 
kneading the product intensively. At the same time, the usually heated 
surfaces of the disk elements and the agitator shaft 23 itself are 
cleaned. During this operation, the material is primarily moved radially 
between two opposing disk surfaces, but some of the product is always 
pressed against the disk elements as a result of positive displacement. 
This positive displacement of the product by kneading elements ensures 
excellent macro-mixing and kneading. However, according to the invention 
the actual micro-kneading for breaking down the agglomerates is 
intensified substantially as a result of the special form of the radial 
kneading-element parts 35 and 36 on the kneading shaft. 
As shown in FIGS. 4 to 8, these radial kneading elements 35, 36 are 
designed so that, during the cycle of movement, the product is first 
scraped off from the disks 26 by means of the scraping edge 41, 45 and is 
guided and pressed into the kneading gap 43, 47 by the diverting surfaces 
42, 46. Very high shearing forces occur in a known way in this confined 
space 43, 47 between a kneading element and the opposite disk and result 
in excellent microkneading and agglomerate breakdown. This cycle of 
movement also contributes essentially to the macro-mixing, since the 
product is moVed axially to and fro between the two opposite disk 
surfaces. The cycle of movement itself becomes clear from the longitudinal 
section according to FIG. 4 and from the associated cross-sections 
according to FIGS. 5, 6 and 7. In these cross-sections, the radial 
kneading elements 35 and 36 have the form of an involute arising from the 
kinematic development of the cycle of movement between the two agitator 
shafts. 
The cross-sections of FIGS. 5, 6 and 7 illustrate a disk shaft, on which 
are arranged four disk elements 26, between which there are interspaces 
for the transport of the product. The disk elements are connected by means 
of the kneading bars 27 in front of a respective interspace. However, the 
kneading effect can be increased if only one interspace for each disk 
surface is provided for the transport of the product and if the other disk 
parts take the form of a solid surface. This results in a larger kneading 
surface for interaction between the radial kneading arms 35, 36 and the 
disks 26. This leads to an intensification of the kneading effect. It is 
further assisted because the kneaded product can escape to a lesser 
extent. 
As already noted in relation to the reduction of the interspaces between 
the disks, the kneading intensity depends on the disk surface which is 
swept by the kneading elements of the kneading shaft. This disk surface 
can be further enlarged if, according to FIGS. 4 to 7, radial disk 
elements 60 are inserted as kneading counterelements in the interspaces 
between the rotating kneading elements 35, 36 in the housing of the 
kneading shaft. The top view in FIG. 9 of two agitator shafts in a 
partially cut away housing, the associated cross-sections according to 
FIGS. 10 to 12 and the developed view in FIG. 13 of the disk shaft, with 
the associated positions of the radial kneading elements of the kneading 
shaft, illustrate an even more effective application of the inventive 
principle. 50 denotes the disk shaft with the disk elements 51 and the 
kneading bars 52 and 53. 54 denotes the kneading shaft, on which the 
kneading elements 55 and 56 with the axial kneading bars 57 and 58 are 
fastened. The characteristic of this version is the axial kneading bars 
52, 53 on the disk shaft and the axial kneading bars 57, 58 on the 
kneading shaft, which each extend only over approximately half the 
distance between the disk planes. Whereas, in the first-described version 
according to FIGS. 4 to 8, the arrangement of the two radial kneading 
elements between the disk surfaces is tied to the relatively flat helix of 
the kneading bar 27, the approximate half-length of the kneading bars on 
the two shafts allows an arrangement of the two radial kneading arms 55, 
56 on the kneading shaft, in which a radial kneading gap for the free 
passage of the product is obtained between the diverting surface of each 
kneading arm and the opposite disk. 
As is evident from FIGS. 10 to 12, in the illustrated version the radial 
kneading elements of the kneading shaft are offset at 180 degrees. This 
makes it possible to narrow or widen the radial kneading gap, as desired, 
either by means of spacing of the disk surfaces or as a result of the 
axial extension of the kneading elements, in order to adapt the kneading 
effect as closely as possible to particular products. Furthermore, the 
free space for pushing the product to and fro between two disk planes and 
consequently also the macro-mixing are improved. 
The axial direction of transport for the product can also be influenced if 
the length of the kneading bars is increased on one side and the opposite 
kneading bar is reduced correspondingly. 
In the version of the kneading elements according to FIGS. 9 to 12, the 
axial kneading bars 57, 58 are attached to the radial kneading elements 
55, 56. It is also possible, however, to form the kneading elements 55, 56 
over the width of the kneading bars, so that a compact kneading tooth is 
obtained. 
The mixing and kneading effect of the radial kneading elements can also be 
improved for many products if the scraping edges and the adjoining 
diverting surfaces for the product are divided so as to form two or more 
product streams which converge only again in the actual kneading gap and 
which are once more kneaded together there under the pressure of the 
shearing forces. 
The subject of the invention and the arrangement of effective additional 
kneading gaps for a better microkneading of the product can be varied in 
many ways, either by changing the speed ratio between the two agitator 
shafts or by varying the disk surfaces, the number of radial kneading 
elements or the number of axial kneading bars. The working principle can 
likewise be varied if the two agitator shafts have either opposite or like 
directions of rotation. 
All the machine surfaces coming in contact with the product are at least 
partially heatable or coolable according to a known system.