EP4032615A1 - Agitator mill - Google Patents

Abstract

Agitator mill with a container-shaped process unit (2) into which a drive shaft (33) extends, and a rotor (17) with a plurality of tools (30) to transfer energy to auxiliary grinding bodies (31), the process unit (2) has a Product inlet (8) and a product outlet (9), via which the product to be ground is fed into and out of the process unit (2), with a motor (3) which drives the drive shaft (33), characterized in that the drive shaft (33) extends from below through a bottom of the process unit (2) into the vertically oriented process unit (2), and the motor (4) is connected to the drive shaft (33) below the process unit to supply power to the drive shaft (33 ) so that the lid can be removed when the process unit (2) is full without having to remove the product or the auxiliary grinding bodies (31).

Description

The invention relates to an agitator mill with a container-shaped process unit, into which a drive shaft extends, and a rotor with a large number of tools in order to transfer energy to auxiliary grinding bodies.

Overview of the field of the invention

Agitator mills are used to comminute and homogenize solid particles (paints and varnishes), in which auxiliary grinding media are intensively moved by means of an agitator shaft. The solid particles are broken up by impact, pressure, shearing and friction. In principle, agitator bead mills can be differentiated with regard to a horizontal or vertical alignment of the grinding chamber. The grinding aids are activated by the agitator shaft, which can be equipped with agitators (tools) such as rods or discs. The grinding chamber is usually filled to a high percentage, for example seventy to ninety percent, with grinding aids in the size range from 0.03 to 9 mm in diameter.

As a rule, agitator mills comprise a grinding container in which an agitator shaft provided with grinding elements is arranged, whereby a grinding chamber is formed between the grinding container and the agitator shaft, into which the grinding elements extend and into which at least one inlet channel and one outlet channel for material to be ground opens and a separating device for auxiliary grinding bodies is provided.

During the grinding process, the product to be ground flows continuously from a product inlet axially to the agitator shaft through the grinding chamber to a product outlet. In an outlet area, the grinding aids are then separated from the product flow by means of a separation system.

The throughput and the grinding bead size are limited in closed agitator bead mills by the separating device. With the help of the separating device, the auxiliary grinding media should be held back securely in the grinding container and must not lead to grinding media compression or clogging, even at high throughput rates. The separating devices can be designed in a known manner as gap systems, centrifugal systems or as external separating systems.

Of the EP 1943022 B1 is based on the task of designing an agitator mill of the generic type in such a way that, particularly when using grinding aids with an extremely small diameter, grinding and dispersing with a narrow particle distribution is achieved even with only one grinding material run through the agitator mill, without the risk of operational disruptions, in particular due to the impact of auxiliary grinding bodies on the protective screen. This is achieved by using the rotor tools attached to the rotor only leave a small gap to the container wall, that the inner space is designed as a grinding material discharge channel and that the tools attached to the rotor in one area as devices to prevent the overflow of auxiliary grinding bodies from the grinding space into the grinding material discharge channel between the auxiliary grinding body return channels and the deflection channel in the circumferential direction of the rotor are arranged overlapping one another on a helical line in such a way that when the rotor is rotated in one direction of rotation, they exert an impulse on the auxiliary grinding bodies that is opposite to the direction of flow.

An agitator mill is from the EP 0 370 022 B1 (according to U.S. 5,062,577 ) known. In this agitator mill, the auxiliary grinding media are centrifuged out of the flow of grinding stock and auxiliary grinding media through the auxiliary grinding media return channels before they reach the protective screen. The protective screen basically has the function of catching worn grinding media, which are too light to be spun off directly through the grinding media return channels, and to serve as a throttle point to build up a back pressure that counteracts the flow of the grinding material. The agitator is provided with agitating tools protruding into the outer grinding chamber. When using extremely small auxiliary grinding media, there is no guarantee that the auxiliary grinding media will not reach the protective screen and clog it over time. In particular when using extremely small auxiliary grinding bodies, correspondingly fine protective screens must be used, which in turn can be damaged very easily if auxiliary grinding bodies collide. If, on the other hand, relatively viscous material to be ground is to be treated when using grinding aids of the usual size, then the protective sieve is partially clogged a considerable pressure build-up in the agitator mill, which also leads to disruption of the grinding process.

From the EP 0 504 836 B1 an agitator mill is known in which a pot-shaped rotor is arranged in a cylindrical housing and is provided with through-slots along its length. An inner stator with a protective screen is arranged inside the rotor. In the outer grinding chamber, tools are attached both to the rotor and to the wall delimiting the grinding chamber. This agitator mill is not suitable for the use of extremely fine grinding media. Otherwise, the problems already explained above also occur here.

From the DE 34 37 866 A1 (according to U.S. 5,011,089 ) an agitator mill is known which has a rotor which is equipped with paddle-shaped tools on its outside. A protective screen is arranged inside the rotor. The rotor consists of rods running parallel to the axis, to which the paddle-shaped tools are attached. The material to be ground is fed in radially. In this agitator mill, the paddle-like design of the agitator tools means that the auxiliary grinding bodies are concentrated in the region of the container wall; defined grinding, in particular by means of extremely small auxiliary grinding bodies, and reliable separation of the auxiliary grinding bodies without the risk of operational disruptions is also not possible with this. The material to be ground flows radially through the packing of auxiliary grinding bodies, ie the material to be ground is placed in a grinding process only over a very short distance. If the material to be ground is only passed through the agitator mill once, only a small grinding progress is therefore achieved.

From the DE 196 38 354 A1 (according to U.S. 5,894,998 ) An agitator mill of the general type is known, in which the protective screen is attached to the cup-shaped rotor and is sealed against the inner stator by means of a mechanical seal. The protective sieve rotates with the rotor, which means that auxiliary grinding bodies that reach it are additionally thrown off.

From the EP 0 546 320 A2 (corresponding U.S. 5,346,145 ) An agitator mill is known, on the rotor of which tools with conveying surfaces are attached, which exert an impulse on the material to be ground and the auxiliary grinding bodies in the direction from the material inlet to the material outlet.

More mills are off DE102013 111 762 A1 , EP 2646160 B1 , EP 2907578 B1 , EP 3536405 A1 , EP 1992412 B1 , EP 1724022 B1 , EP 1724021 A1 , DE 19839210 B4 , U.S. 5,330,112 A known.

Overview of the invention:

The object of the invention is to provide an alternative approach that enables the mill to be used in a broader range.

This object is achieved by the invention according to the features of the claims.

The invention comprises an agitator mill with a container-shaped process unit into which a drive shaft extends. A rotor is preferably clamped to the drive shaft. The drive shaft extends from below into the interior of the rotor. The rotor is usually an elongated round body. This body can have projections, recesses and inner bores. The body of the rotor has a corresponding axial bore. The hole is preferably a blind hole or the end of the hole is closed by an element that allows a counter screw. The bore or the shaft is cylindrical at its ends so that a clamping connection can be created. In one possible embodiment, a screw connection is made from above into the head of the shaft, which pulls the shaft into the bore and thus supports a press connection. The rotor is provided with a plurality of activation pins on its exterior to transfer energy to grinding media. As a rule, as described above, the grinding aids are beads made of metal or ceramic. The activation pins are preferably bolts, in particular made of metal, which are arranged radially on the outside of the rotor. The arrangement of the bolts can vary, so staggered, regular, threaded arrangements can be conceivable.

In order for the product to run or flow through the process unit, it has a product inlet and a product outlet, via which the product to be ground is guided into and out of the process unit. The product to be ground is surrounded by a carrier liquid that is pumped through the processing unit. One speaks of one wet mill. In the preferred embodiment, the product inlet is arranged in the lower area of the processing unit and the product outlet in the upper area, so that the product flows upwards through the processing unit against gravity. Together with this invention, down is where the gravity of the earth is greater and up there, where the gravity of the earth is smaller, or where the path to the center of the earth is shorter, is down. In this way, gravity supports the separation of the product and auxiliary grinding bodies, since they are pulled downwards by gravity and are thus kept away from the separating system. The invention also includes a motor, preferably a three-phase motor, which drives the drive shaft. A key aspect of the invention is that the drive shaft extends from below through a bottom of the process unit into the vertically oriented process unit, and the motor is connected to the drive shaft below the process unit to transmit power to the drive shaft so that the lid can be removed when the process unit is full without having to remove the product or the grinding aids. In this case, gravity has a supportive effect, as the beads are held back from the separation system. This makes it easier to replace wear parts or clogged parts. Different screening stages can also be applied to the ground material. In this way, the sieve can gradually become smaller in the course of the grinding process.

In possible embodiments, the motor is arranged parallel, preferably laterally to the process unit, so that the axis of rotation of the motor is arranged parallel to the drive shaft. In this case, drive belts and pulleys underneath the process unit can Power transmission take place. Chains, gears or gears are also conceivable. Other arrangements of the engine are also conceivable.

In a possible embodiment, the cover can be removed upwards from the process unit by releasing locking means. In this case, the cover is preferably fastened with screws or nuts on the edge or a flange of the outer shell of the process unit. Corresponding seals are provided in order to achieve sufficient tightness.

In one possible embodiment, there are at least two lids, and fastening means of the process unit are designed in such a way that the lids are interchangeable. Interchangeable means that only bolts or screws need to be loosened without changing other structural parts inside or outside the process unit. By replacing the cover, it is possible to switch between a dynamic separating device and a static separating device without having to empty the process unit or change the rotor. In particular, the grinding aids or the product cannot be removed. The rotor is designed not to collide with any of the lids after they are replaced.

In one possible embodiment, the cover or a flange arranged on the cover can be removed upwards in order to change a screen without the process unit having to be emptied or the rotor having to be changed, in particular not to remove the grinding aids or the product. In the case of the static auxiliary device, the cover can also be provided with a flange which only allows access to the sieve without removing the complete cover. This flange can be opened with appropriate quick-release fasteners and access to the screen can be granted. This allows the screen to be replaced, cleaned or exchanged for a finer screen.

In one possible embodiment, the separating device is connected to the removable cover, so that removing the cover also removes the separating device. As a result, by loosening screws or bolts or fasteners outside of the process unit, the entire separating device can be removed upwards at once. It is therefore not necessary to work in the process unit, which makes clean work easier.

Due to the connection of the cover with the separating device, the product outlet is formed in the cover, which is arranged downstream of the separating device in the flow direction of the product. The product output usually starts centrally from the lid and is guided upwards to the side. Other trainings are conceivable.

In addition to activation pins on the rotor, one possible embodiment also provides radially arranged activation pins on the stator, which is located on the inside of the processing unit Poke gaps between spaced rotor activation pins.

In addition, in a possible embodiment, activation pins can be located on the rotor in the axial direction in the bottom area and/or on the top side pointing up and/or down.

This achieves a more intensive excitation of the auxiliary grinding bodies.

In a possible embodiment, the rotor has at its upper end a central recess which is directed towards the cover and is provided with a peripheral wall into which the separating device, which is fixed to the cover, extends from above. The separator may be in the form of a tubular screen extending down from the lid into the process unit. In order to reduce the overall height, the rotor has a corresponding recess, so that the rotor rotates around the screen unit, which is arranged statically inside the rotor and is surrounded by the peripheral wall.

In one possible embodiment of the rotor, return openings are formed in the peripheral wall, which extend from the central recess in the direction of the stator in order to guide the auxiliary grinding bodies back into the space between the stator and the rotor. The openings are used for easy return of the grinding aids, which are transported back by the centrifugal force generated by the rotor. The return openings preferably do not run completely radially, but at an oblique angle or are bent in the direction of rotation, so that a pump vane effect is achieved, as in the case of a jet pump.

In one possible embodiment, a clamping piece is arranged in the recess, which clamps the rotor to the drive shaft, the upper end of which extends into the recess. The drive shaft thus ends just below the bottom of the recess and is fixed there by clamping with the rotor.

In one possible embodiment, the product inlet is formed in the bottom area or in the lower lateral surface of the processing unit, so that the product to be ground flows through the agitator mill from bottom to top.

In one possible embodiment, the dynamic separating device is driven by one or more carriers from the rotor. The drivers extend upwards from the rotor and engage in a corresponding receptacle there, so that no separate drive is necessary. However, it is also possible to provide a separate drive in order to provide different speeds.

In one possible embodiment, the process unit has an outer shell that extends around the stator and forms a stator cooling space with a cooling water inlet and a cooling water outlet. As a rule, the cooling water flows from the bottom to the top like the product flow through the stator cooling space.

In one possible embodiment, the bottom of the process unit has a bottom cooling space extending around the drive shaft with a cooling water inlet and a cooling water outlet. As a result, different cooling temperatures can be used, and the components are also better separated from one another, so that production is simplified in order to be able to exchange the internal wearing parts.

In a possible embodiment, the rotor could also be designed as a cooled variant, in that the cooling medium is fed into the rotor from below through the drive shaft.

Figures description

The figures of the possible embodiments are described below.

It shows

• figure 1 the mill from the side with a partially transparent housing and the components drive, V-belt and processing unit;
• figure 2 a section through the process unit along the shaft;
• figure 3 a section through the process unit along the shaft, with the screen being removed individually from the cover upwards;
• figure 4 in which the lid is fitted with a dynamic separator.

Description of a detailed embodiment

the figure 1 shows the inventive mill from the side, with the housing being partially translucent.

A process unit 2 and a motor 3 (preferably a three-phase motor) are arranged parallel to one another on a machine stand 1, so that their axes of rotation are parallel to one another. The motor shaft is directed downwards and is fitted with a motor V-belt pulley 4. The process unit 2 also has a V-belt pulley 6 formed on the underside. Both V-belt pulleys are connected to one another via a V-belt 5.

A bearing 7 is formed in the shape of a table on the side of the motor housing. The processing unit 2 is arranged on this bearing and a drive shaft 33 extends through the bearing, which is connected to the V-belt pulley 6 on one side and to a rotor 17 arranged in the processing unit 2 on the other side. The motor thus drives the rotor in the process unit.

A product inlet 8 is arranged above the bearing 7 , which enables a product to flow into the bottom area of the processing unit 2 . The product to be ground is pumped against the force of gravity from the bottom up to the cover of the processing unit 2. The product to be ground is in a carrier liquid and is pumped with this through the process unit. The product outlet 9, from which the product to be ground exits, is located in the area of the cover.

Two cooling water chambers are provided to avoid overheating of the product to be ground. These can also be merged into one. The first stator cooling space 19 is formed in the wall area of the process unit 2 . A cooling water access 10 for a stator 16 is provided for this purpose. The process unit 2 is preferably double-walled with an outer shell 14 and an inner shell, which serves as a stator 16 . The stator cooling chamber 19 is flooded with cooling liquid from bottom to top and is also pumped through in this direction. A corresponding cooling water outlet 11 is located in the upper area of the process unit.

Furthermore, a floor cooling chamber 20 is formed in the floor in order to cool the bearing of the drive shaft 33 and the material to be ground in the floor area. For this purpose, a cooling water inlet 12 is formed in the base 12 and a cooling water outlet 13 is formed in the base.

As in the figures 2 and 3 shown, the barrel-shaped process unit 2 comprises the outer casing 14, within which the stator 16 is formed at a distance. The stator cooling chamber 19 is arranged between the two. A grinding chamber 18 is formed around the stator 16, directed inwards, in the center of which the rotor 17 rotates.

The process unit is closed off at the bottom by a process unit floor 21 to which the floor cooling space 20 borders.

The outer shell 14 is usually connected to the process unit base 21 .

Further, a bead drain plug 32 is provided in the process unit bottom to drain the grinding auxiliary bodies 31 downward. The bearing housing serves as a support for the process unit floor. A flange connection 22 of the process unit on the bearing housing is used for this purpose. The process unit is attached to the flange connection 23 by an attachment 23 .

At the top, the process unit is delimited by an upper grinding chamber cover 15 with a receptacle for a sieve unit/static separating device.

the figures 2 and 3 show a grinding chamber cover with sieve installed and removed upwards.

figure 4 on the other hand, shows a dynamic separator. The grinding chamber cover has a bore in which the sieve unit 26 is arranged. The screen unit in turn has a screen cover 27 and a screen 28 adjoining it.

Releasable fasteners 29 and 24 allow both the grinding chamber cover and the sieve unit to be removed, replaced or cleaned.

On the wall of the stator as well as on the rotor there are circumferentially arranged activation pins 30 formed at right angles to the axis of rotation, which extend into the space between the stator and rotor in order to engage in one another and in this way to transfer the rotational energy to the auxiliary grinding bodies 31 . The activation pins can even be on the bottom or top of the rotor and face up or down like the Figures 2-4 demonstrate.

The rotor shows how figure 3 can be seen well, in the upper area on a central recess 41 into which the screen extends when the device is in operation. Through this the screen surface is increased with a compact design at the same time.

The rotor has return openings 25 in its upper region so that auxiliary grinding bodies that are in direct contact with the sieve can be returned to the grinding chamber. These are arranged circumferentially spaced and extend from the upper edge of the recess 41 to its lower edge.

The drive shaft 33 extends almost to the bottom of the central recess 41 through a rotor hub 34. The drive shaft 33 is connected to the rotor hub 34 by a sprag 35 formed at the bottom of the central recess 41. The rotor casing (item 31) then extends around the rotor hub and can be connected to the rotor hub in one piece or detachably.

the figure 4 shows an embodiment of the invention in which the upper grinding chamber cover 36 is designed with a dynamic separating device 40 with a friction gap 37 . The invention can be retrofitted in a short time without emptying the process unit. All you have to do is replace the cover.

Flights 38 transfer the rotary motion from the rotor to the dynamic gap or separator, which has two rings placed closely together, with one of the rings rotating. The ground product is guided through this gap.

The outlet 39 and the bearing housing of the dynamic separating device are formed in the grinding chamber cover.

Reference List

1

machine stand

2

process unit

3

three-phase motor

4

V-belt pulley engine

5

V-belt

6

V-belt pulley process unit

7

storage

8th

product receipt

9

product exit

10

Cooling water access stator

11

Cooling water outlet stator

12

Cooling water access floor

13

Cooling water outlet floor

14

outer jacket

15

Upper grinding chamber cover, intake sieve unit / static separator

16

stator

17

rotor

18

grinding room

19

stator refrigerator

20

Floor Fridge

21

floor process unit

22

Flange connection process unit bearing housing

23

Attachment of the process unit to item 22

24

Fastening item 15 & item 36

25

Return opening in the rotor for auxiliary grinding media

26

Screen unit / static separator

27

Screen lid / lid static separation device

28

Sieve

29

Fastening item 26

30

activation pin

31

grinding aids

32

bead drain plug

33

drive shaft

34

rotor hub

35

clamping piece

36

Upper grinding chamber cover, dynamic gap intake / dynamic separator

37

friction gap

38

Drivers (transmit the rotary motion from the rotor to the dynamic gap)

39

Outlet/bearing housing from the dynamic separator

40

Dynamic separator

41

Central recess rotor

Claims (15)

Agitator mill with a container-shaped process unit (2) into which a drive shaft (33) extends, and a rotor (17) with a plurality of tools (30) to transfer energy to auxiliary grinding bodies (31), the process unit (2) has a Product inlet (8) and a product outlet (9), via which the product to be ground is guided into and out of the process unit (2), with a motor (3) which drives the drive shaft (33), characterized in that the drive shaft (33) extends from below through a bottom of the process unit (2) into the vertically oriented process unit (2), and the motor (3) is connected to the drive shaft (33) below the process unit to supply power to the drive shaft (33 ) so that the lid can be removed when the process unit (2) is full without having to remove the product or the auxiliary grinding bodies (31), the product inlet being formed in the lower area of the process unit of the process unit is so that the liquid product to be ground flows from bottom to top through the agitator mill against gravity. The agitator mill according to the preceding claim , characterized in that the cover (15,27,36) can be removed upwards from the process unit by releasing locking means. The agitator mill according to the preceding claim, characterized in that at least two lids are present, and fastening means of the process unit are designed in such a way that the lids can be exchanged, and by exchanging the lid it is possible to switch between a dynamic separator and a static separator without doing so the process unit is to be emptied or the rotor (17) is to be replaced; in particular, the grinding aids or the product are not to be removed. The agitator mill according to one of the preceding claims, characterized in that the sieve can be removed upwards individually or together with the cover without the process unit having to be emptied or the rotor (17) having to be changed, in particular the auxiliary grinding bodies (31) or not to remove the product. The agitator mill according to any one of the three preceding claims, characterized in that the separating device (40,26) is connected to the removable cover, so that removing the cover also removes the separating device The agitator mill according to one of the four preceding claims , characterized in that in the removable cover (15, 27, 36) the product outlet is formed, which is in the direction of flow of the product after Separating device is arranged. The agitator mill according to one of the preceding claims , characterized in that the rotor (17) is formed on the outside with radially arranged activation pins (30). The agitator mill according to the preceding claim, characterized in that the process unit is designed on an inside as a stator (16) with radially arranged activation pins (30) which extend into spaces between the activation pins (30) of the rotor that are at a distance. The agitator mill according to one of the preceding claims , characterized in that the rotor (17) has a central recess (41) at its upper end, which is directed towards the cover and is provided with a peripheral wall, in which the separating device (28), attached to the lid extends from above. The agitator mill according to the preceding claim, characterized in that the peripheral wall has return openings (25) which extend from the central recess in the direction of the stator in order to guide the auxiliary grinding bodies back into the space between the stator and the rotor. The agitator mill according to one of the preceding two claims , characterized in that a clamping piece (35) is arranged in the recess that clamps the rotor to the drive shaft, the upper one End extends into the recess and / or a screw connection is used as a fixation flows. The agitator mill according to one of the preceding claims , characterized in that the dynamic separating device (40) is driven by one or more carriers (42) from the rotor. The agitator mill according to any one of the preceding claims , characterized in that the motor (3) is arranged laterally from the processing unit (2), preferably with its axis of rotation parallel to that of the drive shaft (33), to be driven via power transmission means (4,5,6). to be connected to the drive shaft. The agitator mill according to one of the preceding claims , characterized in that the process unit has an outer casing (14) which extends around the stator and forms a stator cooling space (19) with a cooling water inlet (10) and a cooling water outlet (11). The agitator mill according to any one of the preceding claims , characterized in that the bottom of the process unit has a bottom cooling space (20) extending around the drive shaft (33) with a cooling water inlet (12) and a cooling water outlet (13).

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