Note: Descriptions are shown in the official language in which they were submitted.
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MIXING KNEADER
The present invention relates to a kneader-mixer for the
carrying out of mechanical, chemical and/or thermal processes
which has at least two axial-parallel rotating shafts on each
of which there are at least kneading and transport elements
succeeding each other in the direction of rotation of the
shafts, kneading and transport elements following each other
in the axial direction of the corresponding shaft which
contains a gap with respect to each other through which some
of the kneading and transport element pass on the other shaft
in each case.
Products must be treated today in many fields of
industry, particularly however in the chemical industry. For
example, in the kneader-mixer described above, two chemical
products must be so intimately mixed together that they at
least partially react. In this case, these products may pass
through any desired aggregate state so that the requirements
made on the kneader-mixer are very high.
In essence, a distinction is made between single-shaft
and double-shaft kneader-mixers. The present invention
concerns a multi-spindle kneader and mixing machine such as
described, for instance, in CH-A 506 322. In that case,
radial disk elements are present on a shaft, and axially
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directed kneading bars arranged between the disks. Kneading
elements developed in frame shape engage between these disks
from the ather shaft. These kneading elements clean the
disks and kneading bars of the first shaft. The kneading
bars on bath shafts, in their turn, clean the inner wall of
the housing.
Further embodiments of multi-shaft kneader-mixers are
described in EP 92 10 88 29Ø
In all of these multiple-spindle mixers and kneader-
mixers it is a question, above all, of freeing all surfaces
which come into contact with the product to be treated, and
in particular, with the heated surfaces, from product
encrustations or attachments. In the above-mentioned
European Patent Application 92 10 88 29.0, this is done
already to a substantial extent; to be sure, due to the gap
between the kneading and transport elements, a ring which is
not cleaned always remains on the inner wall of the housing
both on the agitator shaft and on the cleaning shaft.
The object of the present invention is to create a
possibility for also eliminating this ring.
In order to achieve this object, the kneading and
transport elements succeeding each other in the direction of
rotation of the shaft are arranged at least partially axially
staggered.
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This means that the actual kneading and transport
elements for each shaft clean the corresponding housing
inner wall 100%. This has advantages both for the heat
transfer and for the product transport.
When mention is made in the present case of kneading
and transport elements, these elements have not only the
kneading and transport function, but also the above-
mentioned cleaning function.
In accordance with the invention, there is provided a
kneader for kneading and transporting a product through the
mixture comprising:
a housing having a product inlet and a product outlet;
and
a pair of coaxial shafts rotatably mounted in the
housing for transporting the product from the product inlet
to the product outlet, each of the pair of coaxial shafts
includes a plurality of elements mounted thereon for
kneading and transporting the product wherein the plurality
of elements on each coaxial shaft are axially spaced
thereon to provide a gap therebetween which receives a
portion of an element on the other coaxial shaft wherein
each element includes a radial carrying element connected
to a ring carried on a corresponding coaxial shaft wherein
adjacent rings on the coaxial shaft are separated from each
other by a tubular section.
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A kneading and transport element preferably consists
of a radial carrier element and a kneading bar placed on
the circumference of the carrying element. In this
connection, there is the possibility of equipping both the
radial transport element and the kneading bar in any way
desired. The kneading bar can be developed in cross
section in the manner of a plowshare or be provided with
lateral wings. The carrying element can be segmental,
disk-shaped, wrench-shaped, sawtooth-shaped, shaft-shaped
or developed merely as strips. Here, many possibilities
are conceivable and lie within the scope of the present
invention. It is merely essential that between the
kneading elements and transport elements and here, in
particular, between the kneading bars which axially are
adjacent each other, a gap is present through which some of
the kneading and transport elements pass on the other
shaft. By the axial stagger of the kneading bars from
kneading and transport elements following
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each other in the direction of rotation, assurance is had
that this gap is continuously cleaned.
The kneading and transport element can be placed in any
desired manner on the corresponding shaft and connected with
it. To be sure, these kneading and transport elements must
take up considerable forces, so that it has been found
favorable for them to be integrated into the shaft. In this
connection it is possible to produce the radial carrier
elements together with a ring so that this manufacturing
process is considerably simplified. Furthermore, there is
less danger of the breaking of the radial carrier element in
the case of a one-piece manufacture. The kneading bars are
then preferably welded onto the radial carrier elements.
If the connection with a ring is selected for the
kneading and transport elements, the entire shaft can be
developed in sections. This means that the shaft consists
essentially of individual tubular sections between which the
rings are arranged. Two adjacent rings can then possibly be
separated by an intermediate ring so that in this way the
axial stagger of the kneading bars is determined. This axial
stagger should in any event be so great that it covers the
gap between the two kneading bars preceding each other in
direction of rotation.
In any event, assurance must be had that in all cases
those same kneading and transport elements as have the same
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axial stagger cooperate with each, i.e. mesh with each other.
Only in this way is the result obtained that the two kneading
bars having a different offset do not strike against and
damage each other.
In order to achieve this goal, it is necessary to adapt
the number and shape of the kneading and transport elements,
the speed ratio of the shafts, and the direction of rotation
of the shafts to each other. It is possible to operate the
shafts both in the same direction and in opposite direction.
The speed ratio of the shaft is preferably directly
proportional to the ratio of the kneading/transport bars on
the shafts. Furthermore, the number of bars should be so
determined that upon each revolution of the shaft, the same
shaft transport bars are in engagement with each other.
As a whole, by the present invention there is created a
multiple-spindle kneader-mixer in which both housing inner
walls are completely cleaned. This constitutes the essential
advantage of the present invention, the expense for this
conversion being very slight.
Further advantages, features and details of the
invention will be evident from the following description of
preferred embodiments and by reference to the drawing, in
which:
Fig. 1 is a top view of a kneader-mixer of the invention,
with the housing partially cut away;
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Fig. 2 is a longitudinal section through an agitator shaft
in accordance with the invention;
Fig. 3 is a developed view of the agitator shaft of Fig.
2;
Fig. 4 is a longitudinal section through a cleaning shaft
in accordance with the invention;
Fig. 5 is a developed view of the cleaning shaft of Fig.
4;
Fig. 6 is a diagrammatic view of a part of agitator shaft
and cleaning shaft in position of use; and
Fig. 7 is a front view of the position of use of agitator
and cleaning shaft of Fig. 6.
A kneader-mixer P has, according to Fig. 1, a housing
which consists of several housing sections la, 1b and lc.
The housing sections are coupled to each other by
corresponding flange connections 2. Within the housing
section la, there is a feed pipe 3 for a product to be
treated within the kneader-mixer and in the housing section
lc there is provided an outlet connection 4 for the treated
product.
The product is transported from the feeding connection 3
to the outlet connection 4 by means of two shafts 5 and 6 as
well as kneading and transport elements 7 arranged thereon.
During the transport, a mixing and kneading of the product as
well as preferably a thermal treatment takes place. For this
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purpose, the shafts 5 and 6 and possibly also the kneading
and transport elements 7 as well as (not shown in detail) the
housing wall 8 are heated. For the introduction of a heating
fluid into the shafts 5 and 6 and from there possibly into
the inside of the kneading and transport elements 7,
connections 9 and 10 are arranged around corresponding inlet
and outlet nipples 11 and 12 for the heating fluid conducted
through the shafts 5 and 6. A corresponding guidance of the
heating fluid in jacket surfaces of the shafts 5 and 6 and a
corresponding return through outlet nipple 12 are covered by
the prior art and are therefore not further described.
Between the connections 9 and 10 journal pins 13 and 14
connected with the shafts 4 and 5 engage through a spacer 15
a stuffing box 16 and 17 against the housing 1 being provided
in each case to seal off the shaft 5 or 6. The journal pins
13 and 14 are coupled with each other outside the spacers via
corresponding transmission elements 18 and 19, for instance
gear wheels, the transmission element 19 being connected via
the gearing 20 with a drive 21. Via this drive,21 and the
transmission 20, the transmission element 19 is first of all
placed in rotation, which rotation is transmitted to the
shaft 5. A transmission of this rotary movement to the
transmission element 19 can take place in the same or
opposite direction and with the same or different speed of
rotation. Corresponding stepped-down Bearings are commercial
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and will not be described in detail here.
In Fig. 2 it can be noted that at least a part of the
agitator shaft 5 is assembled of a plurality of pipe sections
30 which receive between each other, at least in each case,
two rings 31 and 32 which in this case are connected to each
other via corresponding welds 33 and to the pipe sections 30.
On the rings 31 and 32 there are arranged the kneading and
transport elements 7 which in each case consist essentially
of a kneading bar 34 and a radial carrying element 35.
Particularly in Fig. 7, it can be noted that the ring 31/32
and the radial carrying element 35 may be made in one piece
while the kneading bar 34 is placed on the radial carrying
element 35. The radial carrying element 35 can furthermore
be developed in any manner desired. In the present
embodiment, it is of strip shape. However, it can also be
disk-shaped, serrated, undulated, annular, segmental or the
like. Only by way of example reference is had to Swiss
Patent Applications 00551/88-0, 00550/88-8, European Patent
Applications 90 11 86 26.2, 91 10 54 97.1, or DE-OS 41 18
884.5.
It is essential in the present invention that the rings
31 and 32 follow each other axially so that the corresponding
kneading and transport elements 7 are arranged axially
offset. In this way, an axial stagger of the kneading bars
34 also takes place, as can be noted from Fig. 3. On each
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ring 31 or 32, there are, in accordance with Fig. 3, in each
case 4 kneading and transport elements 7, these kneading and
transport elements 7 varying in their axial stagger.
From Fig. 3 it can also be noted that, between the ring
31 and the ring 32, there is also an intermediate ring 36
which spaces the rings 31 and 32 so far apart that a gap 37
between two axial successive kneading bars 31 is bridged over
by the following kneading bar in direction of rotation.
The cleaning shaft 6 in accordance with Figs. 4 and 5 is
also composed of pipe sections 30.1, in which connection two
pipe sections 30.1 which follow each other in axial direction
of the cleaning shaft receive between each other two rings
31.1 and 32.1 as well as possibly an intermediate ring 36.1.
In this case also the pipe sections 30.1, the rings 31.1 and
32.1, and the intermediate rings 36.1 are connected to each
other by corresponding welds 33.1.
On each ring 31.1 and 32.1 there is at least one
kneading and transport element 7.1 which also consists of a
radial carrying element 35.1 and a kneading bar 34.1 placed
thereon. The kneading bars 34.1 or radial carrying elements
35.1 of two corresponding rings 31.1 and 32.1 are again
arranged staggered in axial direction so that gaps 37.1 and
37.2 are also axially staggered.
The manner of operation of the present invention will be
explained in particular with reference to Figs. 6 and 7. The
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kneading and transport elements 7 and the kneading and
transport elements 7.1 of the agitating and cleaning shafts 5
and 6 engage in fork shape upon rotation in each other. In
this connection, the speed of rotation is so adjusted that in
each case those rotary and transport elements 7 and 7.1 which
follow each other in the direction of rotation in an axially
offset plane engage with each other. In this way, assurance
is had that all gaps 37, 37.1 and 37.2 are passed over by the
corresponding kneading bars 34 and 34.1 so that no ring can
build up here on a housing intermediate wall or form an
annular torus. In this connection, to be sure, the ratio of
the number of kneading and transport elements on the agitator
shaft to the kneading and transport elements 7.1 on the
cleaning shaft is to be noted. Furthermore, the speed of the
agitating and cleaning shafts 5 and 6 is also to be adapted
to this. If there are the same number of kneading and
transport elements 7 and 7.1 on the agitating and cleaning
shafts 5 and 6, then both shafts are preferably operated with
the same speed. Insofar as only a smaller number of kneading
and transport elements 7 are present on the agitator shaft
(for instance 2 or 4), the cleaning shaft 6 can also be
operated with a higher speed. It must merely be seen to it
that the kneading and transport elements 7 and 7.1 which are
arranged staggered in a plane always cooperate with each
other.
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The ratio of the number of kneading and transport
elements 7 to the kneading and transport elements 7.1 on the
cleaning shaft 6 is as a rule a whole integer, but a ratio of
6:4 is also possible for instance.
Furthermore, this arrangement is also possible both with
the same direction of rotation of the two shafts 5 and 6 and
with opposite direction. Direction of rotation, speed of the
shafts, and number of the kneading and transport elements
should be adapted to the specific product which is being
processed by the kneader-mixer. The same applies also to the
development of the radial carrier elements 35 and 35.1 by the
enlargement of which, for instance, the dwell time of the
product to be machined in the kneader-mixer is increased.
