EP2905081A1 - Basket mill with milling area sealing - Google Patents

Abstract

Immersion mill, which is driven around a stirring shaft (4), comprising a grinding chamber seal between the stirring shaft (4) and a grinding chamber, which is formed by a grinding chamber housing (11), with a slotted screen (8) which has a side wall of the grinding chamber housing (11). forms, with a sealing ring (13) or two split rings (32, 33) which seals the Mahlraumgehäuse (11) against the agitator shaft, marked by a support plate (20) disposed around the agitator shaft and housing the seal ring (13) or the outer split ring, the support plate (20) being floatingly supported relative to the paint space without rotating with the agitator shaft.

Description

The invention relates to a dip mill according to the preamble of patent claim 1.

Mixing devices or dissolvers have a drive which drives a dispersing shaft immersed vertically into the mixture, on which a mixing tool is arranged, which is preferably designed as a circular disk on the outer diameter of which teeth are arranged. Through this disc creates a laminar suction, which leads to the circulation of the goods. Dispersing means in the present case the all-round wetting of primary particles of pulverulent substances, such as e.g. Color pigments, fillers and the like, which usually form agglomerates when poured into the liquid.

To achieve a uniform primary particle wetting, the transfer of high performance to the mix is required. For this reason, a high solids concentration should be selected to avoid spattering during the dispersion process. Only after achieving a homogeneous wetting may be diluted to the working consistency. This will understandably, the wetting of the powdery substances, which are often of different nature and density, is problematic and time consuming.

Dispersing, in the form previously described, is very different from a simple, one-of-a-kind stirring process in which often only liquids are intermixed or produced with each other or liquids with a low proportion of powdery substances.

Device from this area are from the DE 7138140 U . DE 101 451311 A1 . DE 2208443 A . DE 36 16 203 A1 . DE 34 38 766 A1 . DE 26 44 326 A1 . DE 1 941 831 C . DE 18 14 506 A . US 44 51 155 A . DE 82 34 623 U1 . US 36 30 636 A . US 30 30 083 A . US 48 13 787 A . DD 42 040 A5 and US 24 64 588 A known.

These dissolvers have recently been extended to include a so-called dip mill (basket mill, basket mill). This mill is often arranged on the shaft in addition to the dispersing disk (pump disk), has a grinding chamber or grinding chamber in which grinding bodies (beads) are arranged, which are set in motion by a stirring disk. The mix to be ground is usually sucked from above through the grinding chamber, the beads moved through the stirring disc thereby grind the mix. A separating screen, which is preferably arranged in the bottom area of the grinding chamber, separates the beads from the material to be ground, so that they do not pour into the container (see Fig. 1 ).

The dispersing disk (pumping disk), which is preferably arranged below the grinding basket, in this case sucks the mixing material through the immersion mill.

Due to the fact that the grinding chamber is defined by a non-rotating housing, in the middle of a rotating shaft is arranged, whose extensions the Moving beads in the grinding chamber requires a seal between the grinding chamber housing and the shaft. These seals are not seals in the classical sense, but they serve to retain the grinding media (beads with 0.7 - 1.7 mm diameter depending on the sorting) in the so-called grinding room. One speaks also of Mahlkörperseparation.

Standard seals consist of 2 parallel carbide rings (of course including holder) of which the upper part rotates with the stirrer shaft and the lower part is fixed (see Fig. 1 ).

The advantage of this is that hard metal is very wear-resistant and therefore very resistant to abrasive influences caused by the surrounding grinding beads.

The disadvantage, however, is that there is a risk of Mahlkörperzerstörung due improperly set gap. The thus destroyed grinding media (beads) then contaminate the regrind, are expensive to replace and contribute to great wear on the sealing system. Furthermore, these seals are generally expensive to manufacture, and very sensitive to shock caused by a vibrating stirrer shaft.

From the DE2312109A . DE1915158 A . DE4307083 A . CH525028 A . DE3614721 A . DE2908154A . DE2044895 A . JP4322751A . DE2618728A . DE19913243 A . DE2650439 A A number of seals in the field of agitators and stirrer shafts are known. However, none of these documents discloses an alternative sealing insert in the field of dip mills.

From the DE 20 2004 013 056 U1 is a submersible known in which no seal between the shaft and grinding basket is formed. Rather, the gap is chosen so small, that a seal is not necessary. This is only possible by an additional, own storage of the stirring disc in the grinding basket.

From the DE 7023251 U For example, a plastic gasket is known that is disposed between a container and a shaft.

An important application in this area is the DE 10 2009 013 214 whose contents are incorporated herein.

The object of the invention is to provide a seal for a dip mill that is easier to maintain and safer to assemble. Furthermore, shocks of the shaft are to be collected, which often lead to the opening of the seals, which cause jamming in the seal jam and lead to damage to the mating surface.

This object is achieved by a dip mill with the features of claim 1. Advantageous embodiments can be taken from the subclaims.

Specifically, it is a submersible mill, which is driven by a rotating stirrer shaft. This dip mill is guided into a container and is thus in the mix. The immersion mill comprises a Mahlraumabdichtung between the stirrer shaft and a grinding chamber, which is formed by a Mahlraumgehäuse.
Again FIG. 1 can be seen, the millbase flows from above into the mill, where it is sucked by the suction disc below the mill. The grinding media are located in the grinding chamber within the Mahlraumgehäuses. So that the grinding media does not escape from the mill, they are through a slotted screen or retained by a Mahlkörperseparator. Within the grinding chamber also rotate one or more discs, which circulates the material to be ground with the grinding media. The milling and dispersing process takes place between the grinding media and the Mahlraumbegrenzungen.
The slotted screen forms in the direction of flow down the end of the Mahlraumgehäuses. It thus forms the lower wall or the bottom of the Mahlraumgehäuses. Furthermore, a sealing ring is provided in the lower bottom region of the grinding chamber housing, which seals the grinding chamber housing with respect to the stirring shaft.
A support plate is spaced around the agitator shaft and receives the sealing ring, wherein the support plate is floatingly mounted with the sealing ring with respect to the Malraumgehäuse without turning along with the agitator shaft. The support plate is preferably formed as a ring, inside which the sealing ring is located. The underside of the support plate rests on a sliding surface, so that it is floating. However, so that no grinding media can enter this sliding surface, the support plate is prevented by driving pins on rotation and pulled down by spring elements on the sliding surface. Both elements allow some floating in relation to a lateral / horizontal offset of the vertically rotating shaft, so that process-related deflections of the shaft can be better reacted. The load on the sealing element is thus minimized.
The carrier plate is mounted floating on a clamping ring, which is arranged around the agitator shaft and which preferably adjoins the slotted screen or clamps this slotted sieve centrically.
In a preferred embodiment, the clamping ring is attached as a conclusion on the slotted screen to this and thus delimits the slotted screen to the shaft.

As already stated, the carrier plate is pressed by spring force on the clamping ring. The clamping ring is preferably arranged in the flow direction below the support plate and the support plate is pressed by springs, which are designed so that sufficient movement possibilities are available for swimming.

In a preferred embodiment, the sealing ring is made of Teflon.

In a preferred embodiment, the gap between the fastening nut on the agitator shaft and the sealing element which is sealed by the sealing ring is greater than the diameter of the grinding bodies, so that in case of failure of the sealing ring, the grinding media can escape through the gap. Also, in a strong horizontal displacement of the shaft, in which both the seal and the support plate can no longer react sufficiently, the grinding media can enter this radial gap and escape again without damage, since the gap is sufficiently large.

In a preferred embodiment, the sealing or separating gap consists of a rotating and a stationary ring in a material combination hard-soft, or hard-hard with a predetermined radial gap of about 0.1 mm. The material pairing could z. As ceramic hard metal or ceramic Teflon hard coal.

In a preferred embodiment, the carrier plate and the clamping ring are made of a material, each having a different hardness, and in particular different hardened steel, so that they slide on each other.
The gap / radial gap between the fastening nut and sealing element is preferably around 2mm. The ring play is preferably around 5mm. By this approach, the seal can be mechanically relieved and also has less attack surface with respect to the grinding media.

• Fig. 1 zeigt schematisch das Grundprinzip der Tauchmühle nach dem Stand der Technik;
• Fig. 2 zeigt einen Schnitt durch die Tauchmühle mit einer Dichtung gemäß der Erfindung.
• Fig. 3 zeigt einen Schnitt durch die Dichtung im Detail mit Dichtring.
• Fig. 4 zeigt einen Schnitt durch die Dichtung im Detail mit Radialspalt.

Embodiments of the invention are illustrated in the drawings and described below with reference to the figures.

• Fig. 1 shows schematically the basic principle of the dip mill according to the prior art;
• Fig. 2 shows a section through the dip mill with a seal according to the invention.
• Fig. 3 shows a section through the seal in detail with sealing ring.
• Fig. 4 shows a section through the seal in detail with radial gap.

FIG. 1 shows a section through a container 1, in which is arranged to be mixed, dispersing and to be ground Good 2. A stirring and pumping disk 3, which generates a suction, is arranged at the end of a rotating shaft 4. This stirring and pumping disc produces a laminar suction, which causes the mix is sucked from above into a grinding chamber and pulled down through this. The inlet 5 into the grinding chamber is arranged around the shaft. Inside the grinding room Mahlkörper 6 are arranged in the form of balls or beads. These balls are moved by another disk / rotor 7 within the grinding chamber in order to grind and disperse the mix, which is due to the fact that the mix is within the grinding chamber. So that the balls are not sucked into the container, there is a Mahlkörperseparator / Spaltsieb 8, which is designed as a fine sieve and separates the balls from the mix before the mix passes back into the mixing container 1. Around the grinding chamber or around the grinding chamber housing, a cooling 9 is arranged, which ensures that the mix is not heated too much within the grinding chamber. The container also has a cooling, so that excessive temperatures for the material to be ground are avoided. The grinding chamber itself is not rotationally disposed within the container and is secured by rods 10 to the housing (not shown) of the stirring machine outside the container.

The FIG. 2 shows now in detail the grinding chamber with its housing wherein the grinding chamber, together with its housing 11 with respect to the rotating shaft 4, which extends through the grinding chamber, is sealed. Due to the fact that the mix or regrind flows from the top along the shaft into the grinding chamber, there is no need to seal upwards.

The seal is arranged in the lower area A.

The FIG. 3 shows the structure of the seal in section in detail with respect to the area A. FIG. 2 , The stirring shaft 4 rotates. On the agitator shaft, a fastening nut 31 is formed, on which the sealing ring 13 abuts. The fastening nut 31 is thus an extension of the agitator shaft and rotates with it. The sealing ring 13 is located on the agitator shaft and is fixed to the support plate 20 which is formed as a ring. The support plate 20 is floating on the clamping ring 27. There is only a floating connection 29 with a radius of movement of preferably about 5mm of the support plate 20 in the horizontal. The carrier plate is held by springs 22. A driving pin 28 prevents the carrier plate from rotating.

A radial gap 30 is preferably 2 mm, so that the grinding media can pass in the event of a defective seal or Mahlkörperverpressung that would lead to the destruction of the grinding media 6 without this Ablassfunktion.

The FIG. 4 shows the structure of the seal in section in detail with respect to the area A. FIG. 2 , The stirring shaft 4 rotates. On the agitator shaft, a fastening nut 31 is formed, on which a hard material ring 32 or a coating is applied. The fastening nut 31 is thus an extension of the agitator shaft and rotates with it. The second hard ring 33 encloses the stirring shaft with a radial separating gap (sieve gap) 34 of approximately 0.1 mm and is firmly connected to the carrier plate 20, which is designed as a ring. The support plate 20 is floating on the clamping ring 27. There is only a floating connection 29 with a radius of movement preferably about 5mm of the support plate 20 in the horizontal. The carrier plate is held by springs 22. A driving pin 28 prevents the carrier plate from rotating.

LIST OF REFERENCE NUMBERS

1

container

Second

Grinding good

Third

stirring disc

4th

agitator shaft

5th

Inlet into the grinding room

6th

grinding media

7th

Disc / rotor

8th.

Grinding element separator / gap sieve

9th

cooling

11th

Mahlraumgehäuse

13th

seal

14th

submill

20th

support plate

22nd

compression spring

27th

clamping ring

28th

Carrier pin

29th

floating storage

30th

Radial gap

31st

fixing nut

32nd

Indoor split ring

33rd

Exterior split ring

34th

Radial separating gap (sieve gap)

Claims (11)

Immersion mill, which is arranged around a stirrer shaft (4), comprising a grinding chamber seal between the stirrer shaft (4) and a grinding chamber, which is formed by a grinding chamber housing (11), with a slot screen (8) which has a side wall of the grinding chamber housing (11). forms, with a sealing ring (13), or at least two cylindrical rings (32, 33) which seal the Mahlraumgehäuse (11) relative to the stirring shaft, characterized by
a support plate (20) disposed around the agitator shaft and receiving the seal ring (13) or the outer cylindrical split ring (33), the support plate (20) floating with the seal ring or cylindrical outer split ring (33) is mounted in relation to the Malraumgehäuse without turning with the agitator shaft. Submersible mill according to the existing claim, wherein a retention of the grinding media (6) by a defined radial separation gap (34) is ensured, ie an additional dynamic sieve gap, wherein the maximum separation gap preferably calculated by: smallest Mahlkörperdurchmesser divided by 3, which is the radial separation gap dimension in one-sided contact of ring (32) in ring (33) corresponds. Immersion mill according to one or more of the preceding claims, wherein the sealing ring (13) is made of Teflon. Immersion mill according to one or more of the preceding claims, wherein the inner split ring (32) made of a wear-resistant hard material, for. As carbide or ceramic is, wherein preferably the stirring shaft in this area also has a corresponding, wear-resistant coating. Immersion mill according to one or more of the preceding claims, wherein the outer split ring (33) which is firmly embedded in the carrier plate (20) made of a wear-resistant hard material, for. As carbide or ceramic or is made of a wear-resistant elastomer. Immersion mill according to one or more of the preceding claims, wherein the support plate (20) is mounted in a floating manner on a clamping ring (27) which is arranged around the agitator shaft and which preferably adjoins or is fastened to the slotted screen (8). Submersion mill according to one or more of the preceding claims, wherein the clamping ring (27) is fixed on the slotted screen as an abutment of the carrier plate (20). Immersion mill according to one or more of the preceding claims, wherein the support plate (20) is pressed by spring force on the clamping ring (27). Immersion mill according to the preceding claim, wherein one or more springs (22) press the carrier plate (20) onto the clamping ring (27). Immersion mill according to one or more of the preceding claims, wherein the gap (30) between agitator shaft (4) and support plate (20), which is sealed by the sealing ring (13) is greater than the diameter of the grinding media, so that in case of failure of the sealing ring (13), the grinding media can escape through the gap. Immersion mill according to one or more of the preceding claims, wherein the support plate (20) and the clamping ring (27) are made of a material, each having a different hardness, and in particular may be different hardened steel or Teflon steel.

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