Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Cl.OSED TYPE KNEADER
1 Detailed Description of the Invention
(Industrial Utilization Field)
The present invention relates to an improvement
of kneading rotors, particularly intermeshing type
rotors, in a closed type kneader used for kneading
mainly rubber and plastic materials.
Brief Description of the Drawings
Fig. 1 is a front view in longitudinal section
showing a synchronized state of both rotors in a kneader
according to an embodiment of the present invention;
Fig. 2 is a developed plan view showing an
example of a blade structure of a rotor therein;
Fig. 3 is also a developed plan view showing a
blade arrangement relation in right and left rotors;
Figs. 4 to 7 are explanatory views showing in
what state material is pulled in and kneaded by the
rotors;
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l Figs. 8 and 9 are developed plan views showing
examples of rotors according to the present invention;
Fig. 10 is an explanatory view of two-blade
type rotors;
Fig. 11 is a developed plan view showing a
blade arrangement relation in a conventional intermeshing
type rotor;
Fig. 12 is a sectional view of a principal
portion of a conventional non-intermeshing type closed
n kneader;
Fig. 13 is a sectional view of a principal
portion of a conventional intermeshing type closed
kneader;
Figs~ 14 and 15 are explanatory views of
phases and material motions in the presence of speed
ratios in the kneader of the type illustrated in Fig. 12;
Fig. 16 is a plan view of conventional non-
intermeshing type rotors;
Fig. 17 is a plan view of conventional
intermeshing type rotors; and
Fig. 18 is a view explanatory of motions of
material introduced in the rotors of the type
illustrated in Fig. 17.
3 9
1 (Prior Art)
As known, a closed type kneader is a batch
type kneader suitable for kneading such high polymers as
rubbers and plastics and it is an indispensable
mechanical equipment in the field of rubber industry
such as the production of tires. RequiremPnts for this
type of kneaders involve high dispersion of additives
into a main material and a highly homogeneous knea~ing,
capability of a large volume introduction per batch,
high productivity based on a short mixing time, and stable
operation for each batch. According to a general
structure of a closed type kneader, as will be ~escribed
later, a pair of knea~ing rotors are disposed rotatably in
opposed parallel relation to each other within a
kneading chamber of a cylinder provided with heating or
cooling means, and a material feed hopper having a
forcing ram is provided at the top of the kneading
chamber. One batch of material to be kneaded is
introduced at a time from the hopper. The material is
introduced into the kneading chamber by pull-in force
(bite-in ability) into the kneading chamber induced by
the rotors and the pressure of the forcing ram. When
the entire material is completely forced into the
kneading chamber by the ram, there is started
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] homogeneous Xneading of the entire material under
rotation of the rotors. Therefore, it can be said that
in such a kneader, completing the introduction of the
material to be kneaded into the kneading chamber quickly
and stably lead to shortening of the kneading time,
improvement of the mixing performance and stable
operation. On the other hand, as already known, closed
type kneaders are boardly classified in point of
mechanism into non-intermeshing type (tangential type)
kneaders wherein a pair of kneading rotors are not in
mesh with each other, and intermeshing type kneaders
wherein a pair of kneading rotors are in mesh with each
other. Of the two types, the non~intermeshing type
kneaders are generally evaluated as permitting the
introduction of a large volume of material and being
superior in bit-in ability and high in its operability
and stability. On the other hand, the intermeshing type
kneaders are generally evaluated as being high in the
additive dispersing ability and homogenizing ability.
These are also already known. Needless to say,
moreover, it is well known that various inventions and
devices relating to each type of kneaders are existent.
For example, as to non-intermeshing type kneaders, the
applicant in the present case has already filed
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(Problems to be Solved by the Invention~
Of the two types mentioned above, in
intermeshing type kneaders, though their uniformly
additive dispersing ability and highly homogeneously
kneading ability are high, it is generally difficult to
introduce a large amount of material into the kneaders,
and the bite-in ability is poor, so the operability and
productivity are low; besides, unstable bite-in
performance leads to increase in the scatter of quality
between batches, thus making production control
difficult. The existence of such drawbacks common to
intermeshing type kneaders is also a known fact. In
this connection, the bite-in performance of an
intermeshing type kneader and that of a non-intermeshing
type kneader were compared using two laboratory
apparatus. It turned out that the intermeshing type
kneader involved a problem in its bite-in performance
for the reason to be set forth below. One of the
laboratory apparatus is a model kneader having an inside
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1 diameter of a kneading chamber of about 200 mm and an
axial length shortened to 1/3 of the corresponding mlxer
(kneader), in which the material motion in the sectional
direction of rotors can be observed through a glass
window provided in a side face of the kneading chamber.
The other laboratory apparatus is a model kneader having
an inside diameter of a kneading chamber of 100 mm and
an axial length same as that of the corresponding mixer
(kneader), in which there are used rotors each
constituted by a laminate of thin iron sheets and it is
possible to set various blade arrangements, and in which
the kneading chamber is formed of a transparent resin to
permit observation of the material motion in the
interior. In the non~intermeshing type, as shown in
Figs. 12, 14, 15 and 16, a pair of kneading rotors 10,
10 are rotatably disposed in parallel in non-intermeshing
positions within a kneading chamber 6 formed in a
cylinder 5, a hopper 7 provided with a forcing ram 8 is
opened in the upper portion of the kneading chamber 6,
and a door portion 9 is formed centrally of the bottom
of the kneading chamber 6. As shown in Fig. 12, since
the space of a communicating portion 11 at the center of
the kneading chamber 6 is wide, the material fed from
the hopper 7 and introduced under pressure by the
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1 forcing ram 8 is extremely easy to enter the kneading
chamber. Further, since there is a speed riatio (1.1 -
1.2) between the righ~ and left rotors 10, 10, the
action of pulling in a material 12 from the hopper 7 by
both rotors 10, 10 is extremely large, as shown in Fig.
14, at the time of a periodic synchronism (phase 0) of
the tips of blades 10a, 10a which are formed axially
twistedly on the peripheral surfaces of the right and
left rotors 10, 10. This is also true when both rotors
10, 10 are 90 out of phase with each other as shown in
Fig. 15. Further, the flow of the material 12 from the
rotor front to the back surfaces in the kneading chamber
6 and that from the rotor back to the front surfaces are
effected smoothly in an extremely well-balanced state.
In the drawings, P is an arrow indicating a rotating
direction of each of the right and left rotors; Pl is an
arrow indicating the flow of the material 12; and 10a,
10b represent long and short blades formed on the
peripheral surface of each rotor.
On the other hand, in the intermeshing type,
as shown in Figs. 13, 17 and 18, right and left rotors
10, lQ rotatably disposed in parallel and opposedly to
each other within a kneading chamber 6 are in an
intermeshing positional relation, so the inter-shaft
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1 distance of both rotors 10, 10 is relatively short as
compared with that in the non-intermeshing type.
Consequently, the space of a communicating portion 11
formed at the center of the kneading chamber is narrow,
thus making it difficult for the material fed to enter
the same chamber as is apparent from Fig. 13. In the
intermeshing type, moreover, the right and left rotors
10, 10 are rotated at the same speed and their blades
lOa, lOa are 90~ out of phase with each other as shown
in Fig. 13 from the necessity of preventing contact of
the two. Moreover, each blade lOa is axially twisted as
shown in Fig. 17, so the space from the hopper 7 to the
door portion 9 is not opened at a time no matter in what
state of phase both rotors 10, 10 are during their
rotation, thus resulting in that it becomes more
difficult for the material to enter the kneading
chamber. Further, since the blades lOa, lOa of the
right and left rotors 10, 10 are 90 out of phase with
each other and both rotors 10 rotate in directions
opposite to each other as indicated by arrow P, the
material 12 which has been forced in from the hopper 7
through the forcing ram 8 performs motions like playing
catch involvi~g repeated forcing-in motion from this to
the other rotor side and from the other to this rotor
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l side and subsequent bouncing motion, as indicated by
arrow P3. Thus, there was confirmed the problem that
the material 12 merely reciprocated between the right
and left rotors just under the hopper without creation
of a strong material pulling-in action based on
synchronism of both rotors 10, 10 as in the non-
intermeshing type.
(Means for Solving the Problems)
In the present invention, the bite-in ability
of the intermeshing type closed kneader described above
is improved to complete the introduction of the material
to be kneaded in a short time, thereby improving the
productivity and operability of the kneader and making
it possible to effect stable kneading and production.
More specifically, in a closed type kneader having a
pair of intermeshing type rotors, each rotor is a two-
blade type rotor comprising a main blade and an
auxiliary blade having an angle of torsion not smaller
than 0 in the same direction relative to the main
~ blade, the auxiliary blade having a length not smaller
than l/2 of the rotor axial length at the rotor central
part and being disposed for synchronization with the
main blade tip of the other rotor at the rotor central
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part.
In one aspect the present invention provides a
closed type kneader comprising: a casing, two rotors
rotatably mounted in said casing for rotation about parallel
axes, two blades extending from each of said rotors such
that the locus of the tip of at least one of said blades of
one of said rotors overlaps the locus of the tip of at least
one of the blades of the other rotor, said blades of each of
said rotors comprising a main blade extending at an angle of
torsion along the rotor and an auxiliary blade, a tip of
said auxiliary blade having a radius less than that of said
main blade and a length not less than one half of the rotor
axial length and having an angle of torsion not smaller than
0 in the same direction as the angle of torsion of the main
blades, and means for rotating said rotors in synchronism
such that the main blade tip of each rotor is in phase with
the auxiliary blade tip of the other rotor at the axial
centers of the rotors.
(Operation)
Accordi.ng to the above technical means of the
present invention, as in Fig. 1 showing right and left
rotors meshing with each other at the respective axial
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central portions, also as in a development view of one
rotor of Fig. 2 and further as in a development view of
a relative positional relation of right and left rotor
blades of Fig. 3, a pair of intermeshing type rotors
10, 10 are disposed side by side within a kneading
chamber 6 so that the rotors can rotate at the same
speed and their axes are parallel with each other. In
this case, as shown in Fig. 2, the rotors 10, 10 are
each a two-blade type comprising a main blade 1
extending axially at an angle of torsion ~ and an
auxiliary blade 3 extending in the same direction at an
angle of torsion ~ not smaller than 0 relative to the
main blade 1. The auxiliary blade 3 has a length not
smaller than 1/2 of a rotor axial length L. Further, as
lS shown in Figs. 1 and 3, the right and left rotors 10, 10
are disposed so that the auxiliary blade 3 of each rotor
is synchronized with the tip of the main blade 1 of the
other rotor 10 at the rotor central part, whereby the
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1 following action is created.
In Fi~. 1 wherein the right and left rotors
10, 10 are in synchronism with each other, there is a
tip clearance ho between a tip la of the main blade 1
and the casing inner surface of the kneading chamber 6,
like that in conventional intermeshing type rotors. The
auxiiiary blade 3 is in synchronis~ with the tip la of
the main blade 1 of the other rotor 10, and between it
and the said tip la there is an inter-rotor clearance A
which is larger than the aforesaid clearance ho. The
flow of material 12 introduced is as indicated by arrow
P2. In the illustrated condition, the material 12 is
separated into hopper 7 side and door portion 9 side.
Then, the rotors 10, 10 rotate in opposite directions as
indicated by arrow P until facing upward as shown in
Fig. 4. In this state, the space of a communicating
portion formed between the hopper 7 and the door portion
9 is wholly opened, so the material 12 in the hopper 7
drops smoothly as indi~ated by arrow P2. With further
rotation of the rotors 10, 10 into the state illustrated
in Fig. 5, the main blade 1 of the left-hand rotor 10 in
the figure and the auxiliary blade 3 of the other rotor
10 nip the dropping mater ial, and the
material 12 is pulled in toward the door portion 9 side
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1 as indicated by arrow P2 by the rotation of both rotors
10 and the resulting interaction of both blades 1, 3.
Next to the state of Fig. 5 there is obtained the state
of Fig. 1 referred to previously. In this way the
material 12 is sure to be fed under pressure toward the
door portion g. With further rotation of the rotors
10, 10 from the state of Fig. 1, there reappears the
state of Fig. 4 explained previously, in which the space
of the communicating portion between both rotors 10, 10
is opened so the feed of the material 12 from the hopper
7 side is again performed smoothly. On the other hand,
the material 12 which has been pulled in over the door
portion 9 in Fig. 5 passes the tips while undergoing
shear between the casing inner surface of the kneading
chamber 6 and the front surfaces of both rotors 10, 10
and moves to the rotor back surfaces, as shown in Fig.
6. In this case, the amount of the material passing the
tip la side of the main blade 1 is small and the
material 12 located under the rotor front surface is
again pushed out to below the forcing ram 8, but since
the amount of the material passing the tip 3a of the
auxiliary blacle 3 is large, the amount of the material
accumulated on the rotor front surface becomes small.
And when rotors further rotate into the state of Fig. 7,
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1 there is little possibility of the space under the
forcing ram 8 being filled with the material 12 which
has previously been fed and pulled in, so the fall of
the material 12 is not impeded and the material 12 is
continued to be pulled in smoothly. Thus, it is
possible to overcome the problems related to the material
bite-in performance in the conventional intermeshing
type rotors.
(Embodiments)
Partinent embodiments of the closed type
kneader using intermeshing type rotors according to the
present invention will now be described with reference
to Figs. 1 to 10. In the embodiments of the present
invention, the other structural points than a pair of
right and left intermeshing type kneading rotors 1~, 10
may be just the same as in the conventional closed type
kneaders of this type, so the details of a cylinder 5, a
kneading chamber 5, a hopper 7, a forcing ram 8 and a
door portion 9 will not be explained. Only rotor
structures will be described. In Figs. 1 to 3, each
rotor 10 is a two-blade type rotor comprising, as
illustrated one rotor in Fig. 2, a long, main blade 1
twisted at an angle of torsion a from one end side of a
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1 rotor having an axial length L toward the other end side
thereof, and a long, auxiliary blade 3 having an angle
of torsion not smaller than 0 from the one end side
of the rotor toward the other end side thereof in a 180
symmetric position with respect to the main blade l, the
auxiliary blade 3 being formed in the same direction so
that its length is not smaller ~han l/2 of the rotor
axial length. The conventional rotors shown in Figs. 12,
13 and 16, 17 are all four-blade type rotors, while the
two-blade type rotor in the present invention is a rotor
having one blade (one tip) in rotor section as shown in
Fig. 10, with the number of tip being half of that of
the conventional four-b~ade type. As shown in Figr 1,
between the casing inner surface of the kneading chamber
6 and the tip la of the main blade l there is a tip
clearance ho like that in the conventional intermeshing
type rotor blades. Further, in a synchronized stage of
both right and left rotors 10, lO shown in Fig. l, an
inter-rotor clearance A larger than the tip clearance ho
is formed between a tip 3a of the auxiliary blade 3 and
a tip la of the main blade 1 of the other rotor. ~he
numerals 2 and 4 denote a short main blade and a short
auxiliary blade, respectively, which are formed at
angles of torsion contrary to the long, main and
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1 auxiliary blades 1, 3 from the side of the rotor 10
opposite to the side where both blades are formed. The
short main blade 2 has the same tip clearance ho as that
of the main blade 1, and the short auxiliary blade 4
also has an inter-rotor clearance A like that of the
auxiliary blade 3. In the present invention, the rotors
10, 10 having the structure described above are disposed
side by side as right and left rotors so that the
auxiliary blades 3 of both rotors are synchronizable
with the tips la of the main blades 1 of the mating
rotors at the rotor central portions, as is apparent
from the relative blade positions of both rotors lQ, 10
shown in Fig. 3 and from the synchronized state of both
rotors shown in Fig. 1.
According to the structure of the above
embodiment, as seen in the blade correlation of both
rotors 10, 10 shown in Fig. 3, in which the numerals 1,
2, 3 and 4 represent long and short, main and auxiliary
blades of one rotor, while 1', 2', 3' and 4' represent
long and short, ~ain and auxiliary blades of the other
rotor, the main and auxiliary blades 1, 3' are at 0
phase at the rotor central part 0-0, and also in an
axial range ~overlap) X in which the auxiliary and main
blades 3, 1l of both rotors overlap each other, the
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1 3~ ~ ~39
1 phase is near 0. Further, als~ at the main and short
auxiliary blades 1, 4' of both rotors, the phase is near
0, and thus there is obtained synchronism of the right
and left rotors 10, 10 throughout the whole of the
rotors, whereby there is attained the smooth and strong
pull-in action for the fed material 12 explained
previously in connection with Figs. 4 to 7, thus
improving the bite-in performance~
On the other hand, in the conventional
intermeshing type rotors illustrated in Figs. 13 and 17,
18, the rotor blades are arranged as shown in Fig. 11,
the rotor blades lOa, lOa' of both rotors 10, 10 are at
a tip phase of 90 as shown at the central part in the
rotor axis direction which is important in pulling in
the fed material 12. And the chip phases of the two are
deviated from each other throughout the entire rotor
blade arrangement. This causes the problem previously
referred to in connection with Figs. 17 and 18.
Although in the above embodiment the long
auxiliary blad,e 3 is at the same angle of torsion ~ as
the main blade 1, it is not always necessary to set the
two at the same angle of torsion. As in the embodiment
illustrated in Yig. 8, the angle of torsion ~ of the
auxiliary blade 3 may be set at 0, so that the phase
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1 thereof with the main blade 1' of the other rotor is
close to 0 in the range of overlap X, thereby the
bite-in performance can be further improved. If the
angle of torsion ~ is set to the minus side, the phase
of the overlap portion X becomes closer to 0, but this
impedes the axial flow P~ of the material by the main
blade 1 shown in Fig. 8, so is not desirable.
The length of the long auxiliary blade 3 is
not always required to be the same as the length of the
main blade 1 as in the embodiment previously illustrated
in Fig. 2. If only it is in the range of overlap X
(usually about 1/2 of the overall rotor length) as in
the embodiment shown in Fig. 9, there will be obtained
the same effect.
lS (Effects of the Invention)
According to the present invention, the
drawback that it is difficult to introduce a large
amount of material and the operability and productivity
are low because of poor bite-in performance, which
drawback is common to closed type kneaders using
intermeshing type rotors, can be overcome easily by
providing an auxiliary blade so as to synchronize with
the main blade tip of a mating rotor over a length not
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1 shorter than 1/2 of the rotor axial length. In this
point the present invention is extremely advantageous
and superior. By this construction it is made possible
to introduce a large amount of material, improve the
bite-in performance for the material and further improve
the operability and productivityO Moreover, by
stabilizing the bite-in performance it is possible to
avoid increase of the scatter in quality between batches,
maintain stable kneading contents and uniform quality and
facilitate production controlO Besides, since these can
be attained merely by modifying the structure of rotor
blades, the invention can be practised extremely easily.
While the invention has been describe~ with
reference to preferred embodiments, it is not so limited.
Many variations and modifications will now occur to
persons skilled in the art. For a definition of the
invention, reference is made to the following claims.
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