JPH10151333A - Dust stop device for sealed kneader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the coverage of nonlubricating material to each seal part for sealing a kneading chamber from the outside by decreasing sliding speed between each sleeve and a rotor or a frame. SOLUTION: This device has a first sleeve 20 movable on a rotor shaft 11B in the rotational and axial directions, and a second sleeve 35 rotatable together with the first sleeve 20 while permitted to be movable in the axial direction by the first sleeve 20. A first seal part 25 and a second seal part 37 are arranged between the head of the first sleeve 20 and a rotor end surface 4a and between the head of the second sleeve 35 and a frame 12 respectively, and the sleeves 20, 35 are pressed by pressing force of a pressing bolt 18 and a coil spring 36 to hermetically seal a kneading chamber 9. By rotating the first sleeve 20 at the revolving speed (n') about half of the revolving speed (n) of the rotor shaft 11B, the sliding speed of each of the seal parts 25, 37 is lowered to extend the coverage of the nonlubricating material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a closed kneader for kneading materials to be kneaded, such as rubber and plastic, together with various additives, and more particularly to a dust stop for sealing a kneading chamber into which the materials to be kneaded are charged. Related to the device.

[0002]

2. Description of the Related Art Conventionally, a dust stop device in a kneader for rubber, plastic, or the like has been disclosed in, for example,
One described in Japanese Patent No. 29467 is proposed.
The above dust stop device has a dust stop ring fitted between the outer peripheral surface of the rotor shaft and the inner peripheral surface of the end plate and pressed against the flange end surface of the rotor in the casing. By forming a sliding contact portion made of a hard alloy between the dust stop ring and the end surface of the flange of the rotor, the inside of the casing (the kneading chamber) is hermetically sealed while allowing the rotation of the rotor. I have. In addition, in order to prevent a rise in the heat generation temperature of the sliding contact portion that is frictionally slid by the rotation of the rotor, the cooling water flows through each of the conductive jackets formed in the circumferential direction. By supplying lubricating oil to the sliding contact portion through a lubrication hole and forcibly cooling it, it is possible to prevent the occurrence of scorched rubber and the like of rubber and resin (kneaded material) kneaded by the rotor, and to produce rubber and resin products. Quality improvement.

[0003]

However, in the conventional dust stop device of a kneader, lubricating oil is supplied to the sliding contact portion in order to improve the slidability at the sliding contact portion and lower the heat generation temperature. However, if rubber or resin (kneaded material) is kneaded by the rotor in such a lubricated state, the running cost of the lubricating oil becomes excessive. Further, when lubricating oil is supplied to the sliding contact portion, the lubricating oil enters the casing from the gap of the sliding contact portion, and the lubricating oil is mixed into rubber, resin, and the like kneaded by the rotor. In particular, when lubricating oil is mixed into rubber, resin, or the like colored in a color other than black (white, blue, or the like), problems such as discoloration occur, and the quality of rubber or resin products deteriorates. Further, the lubricating oil flows to the outside of the kneader from between the dust stop ring and the rotor shaft, and there is a problem in terms of facility environment or safety.

As a means for solving the problems of the conventional dust stop device of the kneading machine as described above, a friction and wear material is used for the sliding contact portion so that no lubricating oil needs to be supplied. It is conceivable to adopt a lubrication method.

However, in recent years, the number of rotations of a rotor for kneading rubber, resin, or the like has been increased from the conventional low speed rotation (40 rpm) to high speed rotation (80 to 90 rpm) from the viewpoint of improving productivity.
m), as described above, it is difficult to simply use friction and wear material to make the sliding contact portion non-lubricated. The surface pressure of the dust stop ring against the flange end surface of the rotor under kneading of rubber or resin due to rotation of the rotor is not so high (5 kgf / cm).
^{In the case of} a kneader of a class having a large kneading capacity (for example, 270 liters or 370 liters) of rubber or resin, the above-mentioned sliding contact portion becomes large, so that the peripheral speed due to the rotation of the rotor becomes extremely high. (For example, 2-2.5m
/ Sec), in particular, there is no stable friction and wear material of a quality that can withstand the above peripheral speed and can be used under non-lubricated conditions.

[0006] Therefore, even if there is a friction and wear material that can withstand the above-mentioned peripheral speed, it becomes expensive, and a durability test or the like to determine whether or not it can actually withstand the above-mentioned peripheral speed is required. It takes time to commercialize. In addition, when a resin-based friction wear material is used, it is necessary to verify the effect when a chemical contained in the friction wear material is added to rubber, resin, or the like.

The dust stop device of the internal mixer according to the present invention reduces the relative sliding speed between each sleeve and the end face of the rotor or the frame, so that the sealing unit for sealing the internal mixing chamber from the outside can be provided. An object of the present invention is to increase the application width of lubrication-free materials.

[0008]

According to a first aspect of the present invention, there is provided a dust stop device for a closed type kneading machine, comprising: a frame for defining a kneading chamber; A rotor having a rotor body disposed and a shaft protruding from a through hole of the frame; a first sleeve fitted rotatably and axially movable with respect to the shaft; A first seal portion provided on the rotor portion where the distal end of the one sleeve and the distal end face each other, and allowing relative rotation between the rotor and the first sleeve, and rotatable with respect to the first sleeve A second sleeve fitted movably in the axial direction;
A second seal portion provided on the frame portion where the tip of the sleeve and the tip face each other, and allowing rotation of the second sleeve with respect to the frame; and rotating the first sleeve at a rotation speed lower than the rotation speed of the rotor. The driving means for rotating in the rotation direction, the first pressing means for pressing the first sleeve against the first seal portion, and the second sleeve co-rotating with the first sleeve are moved relative to each other in the axial direction. And second pressing means for pressing against the second seal portion while allowing. Accordingly, when the first sleeve is rotated in the same direction at a rotation speed lower than the rotation speed of the rotor, the relative sliding speed between the first sleeve and the rotor in each seal portion, or the sliding of the second sleeve with respect to the frame. Speed can be reduced. Further, when each sleeve is pressed against each seal portion by each pressing means, the kneading chamber can be reliably sealed, for example, the rotor itself moves in the axial direction during kneading, and each sleeve relatively moves. Also, it is possible to secure a predetermined pressing force against the rotor and the frame and maintain the airtightness in the kneading chamber.

According to a second aspect of the present invention, in the dust stop device of the closed-type kneader, the driving means may be arranged such that the driving means rotates the first rotational speed at a rotation speed as low as about half the rotation speed of the rotor.
This is to rotate the sleeve. Thereby, the sliding speed of the first seal portion and the second seal portion becomes the same speed,
As a result, the sliding speed can be reduced to about 1/2 of the rotation speed of the rotor.

According to a third aspect of the present invention, the driving means transmits the rotation of the rotor shaft to the first sleeve. Thus, the first sleeve can be rotated with a simple structure while synchronizing with the rotor.

According to a fourth aspect of the present invention, the first and second seal portions are formed of a non-lubricated material. Thus, by reducing the sliding speed of each seal as described above, a non-lubricated material can be used in each seal.

According to a fifth aspect of the present invention, there is provided a dust stop device for a closed kneader, wherein the first pressing means and the second pressing means are provided between the first sleeve and the second sleeve. It is composed of a stretched spring member. Thereby, while pressing the first sleeve by the first pressing means,
The second sleeve can be pressed against the second seal portion via the spring member.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a dust stop device of an internal mixer according to an embodiment of the present invention will be described with reference to FIGS.

First, the overall structure of a closed kneader using a dust stop device according to the present invention will be described with reference to FIGS. 3 and 4, reference numeral 1 denotes a chamber of a closed kneader X, 2 denotes a drop door, 3 denotes an outlet, 4 denotes a kneading rotor (hereinafter referred to as "rotor 4"), 5 denotes a latch, and 6 denotes a floating weight. , 7 are supply ports, and 8 is a door opening / closing mechanism.

The chamber 1 forms two circular cylindrical spaces whose cross sections communicate laterally with the lower portion of the floating weight 6 and the door top 2a of the drop door 2, and is fixed to both ends of this space. Frame 1
2 define a kneading chamber 9. The chamber 1 is mounted on a chamber cover 10 arranged on the ground. Two rotating rotors 4 are arranged in the kneading chamber 9. Each rotor 4 includes a rotor main body 11A that is arranged in the kneading chamber 9 and kneads the material to be kneaded, and a rotor shaft portion 11B that is integrally formed with the rotor main body 11A and protrudes outside from the through hole 12A of the frame 12. Consists of Each rotor 4 has the rotor shaft 11B
3 and is driven to rotate by a drive motor (not shown) (shown in FIG. 5). Accordingly, each rotor 4 is driven by the rotation of the rotor shaft 11B.
The rotor main body 11A rotates so as to sweep the inner wall of the kneading chamber 9, and rubber or resin pushed into the kneading chamber 9 from the supply port 7 by raising and lowering of the floating weight 6 (hereinafter, referred to as "kneaded material"). Is kneaded.

The above-mentioned drop door 2 closes the discharge port 3 at the bottom of the kneading chamber 9 with the door top 2a during kneading to enable kneading of the material to be kneaded by the rotor 4, and swings downward after kneading to ground. It is opened so as to fall to the side, and the material to be kneaded can be discharged. The opening and closing of the drop door 2 as described above is performed by the door opening and closing mechanism 8. The latch 5 pushes the drop door 2 toward the chamber 1 to maintain the tightness in the kneading chamber 9 during kneading of the material to be kneaded, and is retracted from the drop door 2 after kneading to open the drop door 2. Is what makes it possible.

Between the outer peripheral surface of the rotor shaft 11B and the through hole 12A of the frame 12, as shown in FIG.
Is driven to rotate. The dust stop device Y is configured to be pressed against the rotor 4 by a yoke 16 facing the frame 12 with an interval. The yoke 16 is attached to the frame 12 by bolts 17, and is provided with a pressing bolt 18 (first pressing means) for pressing the dust stop device Y toward the rotor 4, and a fluid pressure cylinder 19 for holding the yoke 16 on the frame 12. ing. The hydraulic cylinder 19 holds the yoke 16 with respect to the frame 12 by moving the tip of the cylinder rod into contact with the frame 12 and moving the rod forward and backward.

Next, referring to FIG. 1, a specific configuration of the dust stop device Y used in the internal mixer X will be described.

In FIG. 1, a dust stop device Y includes an outer peripheral surface of a rotor shaft 11B and a through hole 12A of a frame 12.
The first sleeve 20 is rotatably and axially movable with respect to the rotor shaft 11B via a plain bearing or the like. It is fitted. A flange 23 projecting upward between the frame 12 and the yoke 16 is integrally formed on the outer peripheral surface of the first sleeve 20. The first sleeve 20 is pressed by the pressing bolt 18 of the yoke 16 with the bearing 24 (thrust bearing) interposed. Thus, when the pressing bolt 18 is pressed via the above-described yoke 16, the first sleeve 20 moves in the axial direction of the rotor shaft 11 </ b> B and is pressed against the rotor 4 via the first seal 25. ing.

The first seal portion 25 comprises a pair of friction wear materials 26 and 27 (lubricating material).
And 27 are fixed to the tip of the first sleeve 20 and the flange end face 4a of the rotor body 11A facing the tip. The friction wear members 26 and 27 are in close contact with each other between the first sleeve 20 and the rotor 4, and are pressed by the pressing force of the pressing bolt 18 so as to seal the kneading chamber 9 from the outside.

A sprocket 28 is connected to the outer peripheral surface of the first sleeve 20 between the yoke 16 and the flange 23. An endless chain 30 fitted on the sprocket 29 of the driving means 15 is mounted on the sprocket 28. The driving means 15 has a driving motor 32 for rotating the sprocket 29 via a speed reducer 31. Thereby, the drive motor 32 of the drive means 15
When the sprocket 29 is rotated at the rotation speed reduced by the speed reducer 31, the frictional wear material 26 of the first seal portion 25 and the rotor shaft portion 11B are centered via the endless chain 30 and the sprocket 28. 27, the first sleeve 20 rotates.

As shown in the drawing, a second sleeve 35 is provided on the first sleeve 20 which is fitted onto the rotor shaft 11B. The second sleeve 35 is arranged in the axial direction between the outer peripheral surface of the first sleeve 20 and the through hole 12A of the frame 12, and the key groove formed on the inner peripheral surface is
Are fitted around the first sleeve 20 so as to be rotatable together with the first sleeve 20 so as to be movable in the axial direction. Further, the second sleeve 35 is stretched between the flange 23 and the second sleeve 35 and is moved toward the rotor 4 by the spring force of a coil spring 36 which is a part of the second pressing means. Is pressed. 40 is the first sleeve 20
Is a rubber O-ring interposed between the first sleeve 20 and the second sleeve 35. Since the first sleeve 20 and the second sleeve 35 rotate together, the O-ring 40 can also be sealed.

The second seal portion 37 is composed of a pair of frictional wear materials 38 and 39 (lubricating material). Each of the frictional wear materials 38 and 39 is connected to the tip of the second sleeve 35 and the frame 12 facing the second sleeve 35. It is fixed to the outer side surface 12B. Each of the friction wear materials 38 and 39 is connected to the frame 12 and the second sleeve 2.
0, and is press-contacted so as to seal the kneading chamber 9 from the outside by the pressing force of the pressing bolt 10 and the spring force of the coil spring 36. Accordingly, when the first sleeve 20 is moved toward the rotor body 11A via the pressing bolt 18 serving as the first pressing means, the friction wear material 26 of the first sleeve 20 is pressed by the friction wear material 27, The second sleeve 35 also moves in the same direction via the coil spring 36 as the second pressing means together with the first pressing means,
The friction wear 38 of the sleeve 20 can press against the friction wear 39. Then, each pressed seal portion 25
And 37, the inside of the kneading chamber 9 is completely sealed from the outside.

The dust stop device Y of the closed kneader X in this embodiment is configured as described above. Next, the operation of the dust stop device Y will be described with reference to FIG.

First, the rotor shaft 11B is rotated at a predetermined rotation speed n while pushing rubber or resin (kneaded material) from the supply port 7 into the kneading chamber 9 by raising and lowering the floating weight 6 of the closed kneader X. Then, the rotor body 11A connected thereto rotates so as to sweep the inner wall of the kneading chamber 9, and kneads the material to be kneaded (shown in FIGS. 3 and 4).

At the same time as the kneading by each rotor 4 is started, the drive motor 32 of the drive means 15 is driven,
The sprocket 29 is rotated by the reduction gear 31 at a rotation speed lower than the rotation speed n of the rotor shaft portion 11B. As a result, the rotation of the sprocket 29 causes the first sleeve 20 to move through the endless chain 30 and the sprocket 28 to the rotor shaft 1.
1B, the second sleeve 35 is rotated in the same direction at the rotation speed n 'while being rotated at the reduced rotation speed n' in the same direction as 1B.

When the first sleeve 20 is rotated at the rotation speed n 'as described above, the frictional wear materials 26 and 27 of the first seal portion 25 slide against each other, and the first seal portion 25
, The relative sliding speed Ns between the first sleeve 20 and the rotor 4 is Ns = nn ′, and the first sleeve 20
Can be reduced as compared with the sliding speed Ns = n when the rotor is not rotated relative to the rotor 4. On the other hand, the second sleeve 25 is rotated at the rotation speed n ′ because the frictional wear material 38 of the second seal portion 37 slides against the frictional wear material 39 of the frame 12, so that the sliding speed Ns with respect to the frame 12 is increased. 'Becomes Ns' = n'.

As described above, when the first sleeve 20 is rotated in the same direction at a rotation speed n ′ lower than the rotation speed n of the rotor 4, the sealing in the kneading chamber 9 is improved by the seal portions 25 and 37. The first sleeve 20 and the rotor 4 and the second sleeve 35 can reduce the sliding speed Ns of the frame 12 while maintaining the same.
And 26 can be reduced. As a result, the first seal portion 25 in which the first sleeve 20 and the rotor 4 slide,
And each of the friction and wear materials 25 and 26 constituting the second seal portion 37 in which the second sleeve 35 and the frame 12 slide.
The width of application of the friction wear material to 38 and 39 can be widened.

The number of revolutions n 'for rotating the first sleeve 20 (second sleeve 35) depends on the rotor shaft 11B.
It is preferable to rotate at a rotation speed reduced to about 1/2 (n '= n / 2) of the rotation speed n of the above.

That is, as the rotational speed n 'of the first sleeve 20 approaches the rotational speed n of the rotor shaft 11B, the sliding speed Ns (Ns = n-
n ′) can be further reduced, but with this, the rotation speed n ′ of the second sleeve 25 also approaches the rotation speed n of the rotor shaft portion 11B. The sliding speed Ns'(Ns' = n ') will increase. Therefore, although the frictional wear of the frictional wear materials 26 and 27 of the first seal portion 25 can be further reduced, the frictional wear materials 38 and 3 of the second seal portion 37 can be reduced.
The frictional wear of No. 9 increases, and if the sliding speed increases (the second seal portion 37) is included, the dust stop device Y cannot be completely lubricated. Conversely, when the rotation speed n ′ of the first sleeve 20 is extremely lower than the rotation speed n of the rotor shaft portion 11B (when the rotation speed n ′ approaches 0), the sliding speed N ′ is reduced.
s increases, and the sliding speed Ns ′ of the second sleeve 35 decreases. In this case as well, a portion where the sliding speed increases (the first seal portion 25) is included. Y cannot be lubricated as a whole.

In view of the above, the first sleeve 20
The rotation speed n ′ of the rotor shaft portion 11B to １ ／
In this case, the sliding speed Ns (Ns = n−n ′) between the first sleeve 20 and the rotor 4 and the sliding speed Ns ′ (Ns ′ = n ′) between the second sleeve 35 and the frame 12 are obtained.
Are substantially equal to each other, and are の of the rotation speed n of the rotor shaft portion 11B.
This is because the degree of friction and wear of 7, 38 and 39 can be made substantially the same, and the whole dust stop device Y can be lubricated without including a portion where the sliding speed increases.

When the respective sleeves 20 and 35 are rotated together with the rotation of the respective rotors 4 to knead the material to be kneaded by the rotor main body 11A, the respective rotors 4 are brought into the rotor main body 1A.
1A can be reciprocated helically, and can be reciprocated in the axial direction by the play of the bearing 13 by receiving the force from the material to be kneaded. At this time, when play occurs in which each rotor 4 reciprocates in the axial direction, each seal portion 25, 37
When the pressing force of the pressing bolt 18 causes the first sleeve 20 to move together with the rotor shaft 11B, and the coil spring 36 to move the second sleeve 35 relative to the first sleeve 20, a gap is formed. The portions 25 and 37 function so as to be in close contact with each other, so that the inside of the kneading chamber 9 is always kept in a sealed state to prevent the kneaded material from leaking out.

When kneading of the material to be kneaded by the closed kneading machine X is completed as described above, after the drop door 2 is opened and the discharge port 3 is opened as shown in FIGS. The kneaded material later is taken out.

In the dust stop device Y of the present embodiment, as shown in FIG. 1, the drive means 15 for rotating the first sleeve 20 is separately provided, but the invention is not limited to this. Not something. For example, as shown in FIG. 2, a sprocket 45 is attached to the outer peripheral surface of the rotor shaft 11B.
And an endless chain 49 is attached to one side 47 of a pair of sprockets 47, 48 fixed to the drive shaft 46.
And the endless chain 30 hung on the sprocket 28 of the first sleeve 20 is interlocked with the sprocket 48. Thus, when the rotor shaft 11B is rotated, the rotation is transmitted to the first sleeve 20 via the sprocket 45, the driving shaft 46, the sprocket 28, and the like, and the first sleeve 20 is connected to the rotor shaft 11B.
B can be rotated in the same direction.

The rotation speed n 'of the first sleeve 28
Can be made lower than the rotational speed n of the rotor shaft portion 11B, for example, by making the outer diameter of the sprocket 45 of the rotor shaft portion 11B smaller than the outer diameter of the sprocket 28 of the first sleeve 20. 4
By adjusting the outer diameter relationship of No. 5, the rotation speed n ′ of the first sleeve 20 can be reduced to about の of the rotation speed n of the rotor shaft portion 11B. As described above, when the driving means 15 for rotating the first sleeve 20 is taken by the rotation of the rotor shaft 11B, a drive motor 32 and a speed reducer 31 for rotating the first sleeve 20 are required. do not do. Further, when the rotor 4 is started and stopped, the second
The rotation of the sleeve 35 can be easily secured.

Further, in the dust stop device Y of the present embodiment, the coil spring 36 is shown as the second pressing means. However, the present invention is not limited to this.
The second sleeve 35 may be pressed against the frame 12 via a bearing (thrust bearing) by a pressing bolt and a spring provided separately from the sleeve 20. In particular, since the frame 12 does not move in the axial direction unlike the rotor 4, a yoke structure such as the first pressing means for absorbing the axial vibration as shown in FIG. 5 is not required. Furthermore, although the frictional wear material 27 of the first seal portion 25 is provided directly on the end surface 4a of the rotor body 4, the present invention is not limited to this, and another member having the frictional wear material ( For example,
The first sealing portion 25 may be configured by detachably fitting the flanged coloring ring to the rotor shaft portion 11B. Also, the friction wear material 39 of the second seal portion 37 can be formed by a flanged coloring in the same manner.

[0037]

As described above, in the dust stop device of the internal mixer according to the first aspect of the present invention, when the first sleeve is rotated in the same direction at a rotation speed lower than the rotation speed of the rotor, the first seal in each seal portion is reduced. The relative sliding speed of the one sleeve and the rotor or the sliding speed of the second sleeve with respect to the frame can be reduced. Further, when each sleeve is pressed against each seal portion by each pressing means, the kneading chamber can be securely sealed,
For example, even if the rotor itself moves in the axial direction during kneading, the sleeves move relatively to maintain the tightness of the kneading chamber. As a result, the width of application of the non-lubricating material to each seal portion can be widened, and a non-lubricating system can be realized at low cost without a problem of chemical resistance to the material to be kneaded.

[0038] In the dust stop device of the closed type kneader of the second aspect, in addition to the effect of the first aspect, the rotation speed of the rotor at which the sliding speed of the first seal portion and the second seal portion becomes the same speed is obtained. Since the sliding speed can be reduced to about ２, the applicable range of the non-lubricated material can be expanded without including a portion where the sliding speed increases.

According to the third aspect of the present invention, in addition to the effects of the first and second aspects, the first aspect of the present invention provides
Since it is not necessary to separately provide a driving means to rotate the sleeve, the first sleeve can be rotated with a simple structure while synchronizing with the rotor.

In the dust stop device of the closed type kneader of the fourth aspect, in addition to the effect of the first aspect, the sliding speed of each seal section is reduced as in the first aspect so that each seal section has no lubrication. Material can be used.

According to a fifth aspect of the present invention, in addition to the effects of the first aspect, the first kneading means presses the first sleeve and the second kneading means via the spring member.
Since the sleeve can be pressed against the second seal portion, each sleeve can be pressed against each seal portion with a simple structure.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a dust stop device of a closed kneader.

FIG. 2 is a cross-sectional view showing the configuration of another dust stop device of the internal mixer.

FIG. 3 is a longitudinal sectional view showing a configuration of an internal mixer.

FIG. 4 is a cross-sectional view showing the configuration of the internal mixer.

FIG. 5 is a cross-sectional view showing a configuration around a dust stop device of the internal mixer in FIGS. 3 and 4.

[Explanation of symbols]

 X Hermetic kneader Y Dust stop device 1 Chamber 4 Rotor 9 Kneading chamber 11 Rotor shaft 12 Frame 15 Rotation drive source 18 Pressing bolt (first pressing means) 20 First sleeve 25 First seal portion 35 Second sleeve 36 Spring Member (second pressing means) 37 Second seal portion

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshinori Kurokawa 2-3-1, Shinhama, Arai-cho, Takasago-shi, Hyogo Inside Kobe Steel, Ltd. Takasago Works

Claims (5)

[Claims] 1. A rotor having a frame for partitioning a kneading chamber, a rotor body rotatably disposed in the kneading chamber, and a shaft protruding from a through hole of the frame; A first sleeve fitted rotatably and movably in the axial direction, a first sleeve provided at a tip of the rotor facing the tip of the first sleeve, and a relative position between the rotor and the first sleeve. A first seal portion permitting a typical rotation; a second sleeve fitted coaxially and axially movably with the first sleeve; and a front end of the second sleeve and the front end facing each other. A second seal portion provided on the frame portion to allow rotation of the second sleeve with respect to the frame; and a drive for rotating the first sleeve in a rotor rotation direction at a rotation speed lower than the rotation speed of the rotor. Moving means, a first pressing means for pressing the first sleeve against the first seal portion, and a second sleeve co-rotating with the first sleeve, the second sleeve allowing relative movement in the axial direction. And a second pressing means for pressing against the sealing portion. 2. The dust stop device for a closed kneader according to claim 1, wherein said drive means rotates said first sleeve at a rotation speed as low as about 1/2 of the rotation speed of said rotor. 3. The dust stop device for a closed kneader according to claim 1, wherein said driving means transmits the rotation of said rotor shaft to said first sleeve. 4. The dust stop device for a closed kneader according to claim 1, wherein the first seal portion and the second seal portion are formed of a non-lubricated material. 5. The closed kneading apparatus according to claim 1, wherein said second pressing means comprises said first pressing means, and a spring member stretched between said first sleeve and said second sleeve. Machine dust stop device.