DE20021758U1 - Impact mill with striking tools on a motor-driven rotor - Google Patents

Description

PATENT AND LAWYERS MEINKE, DABRINGHAUS AND PARTNER GbR

PATENT ATTORNEYS-JULIUS MEINKE, DIPL-INQ.

WALTER DABRINGHAUS, dipl.-ing. JOCHEN MEINKE, dipl.-ing.

LAWYER

THOMAS MEINKE

ROSA-LUXEMBURG-STRASSE 44141 DORTMUND

TELEPHONE (0231)58 41 TELEPHONE (0231) 14 76 info ©patent-recht.de

PO BOX 10 46

44046 DORTMUND, December 20, 2000

DRESDNER BANK AG DTMD ₁ Account No. 1 148 047 (bank code 440 800 50) POSTBANK DORTMUND, Account No. 542 02-463 (bank code 440 100 46)

FILE NO. 1/16069 D/Dr

Applicant: Dipl.-Ing., Dipl.-Geol. Michael Sniehotta Spanenkamp 30b, 45699 Herten

"Impact mill with impact tools on a
motor-driven rotor"

"Impact mill with impact tools on a motor-driven rotor" _^

The invention relates to an impact mill with impact tools on a motor-driven rotor, wherein the grinding tools interact with a stationary cylindrical impact wall as well as with a grinding material feed and a pneumatic grinding product discharge.

Such mills are known in various designs. DE 197 23 705 Cl shows such a mill for fine grinding with a vertical rotor axis on which a crushing rotor with grinding bars is arranged. The material to be ground is fed into the mill from below via a lower screw-shaped inlet housing, crushed via the grinding bars and guided upwards and discharged via an upper, again screw-shaped sifter.

DE-OS 198 35 144-Al shows a mill with a horizontally positioned drive shaft for the rotor with impact plates, whereby the material to be ground is fed axially, conveyed radially through an annular space in the rotor to the impact bars and then discharged downwards in the direction of gravity from an annular space surrounding the rotor.

Due to the selected flow patterns, the known mills sometimes have the problem that, for example, the return of ground material that has not yet reached the desired grain size can only be carried out outside the mill. The housing designs are sometimes complex, and the type of drive motor arrangement often requires a relatively large amount of space.

The invention is based on the object of creating an impact mill which enables a compact design as well as the return of the ground material within the mill itself.

With an impact mill of the type described at the outset, this object is achieved according to the invention by a grinding material feed arranged in the upper region of the impact tools in the direction of gravity, a receiving space for the grinding material provided below the rotor in the direction of gravity, a conveying air supply for the grinding product assigned to the receiving space, wherein the rotor is carried by an impeller or spoked wheel with passage openings for the grinding product guided from bottom to top by means of conveying air.

The mill design according to the invention has a number of advantages. For example, the material to be ground can be conveyed after passing through the grinding chamber by means of a conveyor

The flow of material through the interior of the rotor allows for the immediate return of insufficiently ground material above the rotor into the grinding chamber, as well as a very compact design, since a drive motor can be flanged directly onto the rotor shaft.

Further advantages and features emerge from the subclaims. It can be particularly useful if the grinding material receiving space is designed in the shape of a funnel with a large number of air inlet slots, the head of the funnel being provided with a fixed air guide device into which the hub of the impeller carrying the impact tools protrudes as a concentric flow divider. The air inlet slots in the wall of the grinding material receiving space can be arranged vertically and horizontally, they are surrounded on the outside by a helical conveying air supply in order to achieve the most even distribution of the air speed in the receiving funnel.

According to the invention, the impact mill has a concentric flow channel, which is formed by the hub with flow divider on the one hand and the air guide device protruding into the interior of the rotor carrying the impact tools on the other. The air thus flows upwards from the interior of the grinding material receiving hopper, flows around the hub of the drive shaft and is guided upwards through an annular space

into an upper spiral-shaped discharge, which is centrally penetrated by the drive shaft.

In order to enable the return of the ground material which has not reached the desired grain fineness, it can be provided that a removal ring space with adjustable removal openings is arranged downstream behind the impeller on the outer circumference of the flow channel.

By conveying the ground material from bottom to top through the interior of the rotor, the flow conditions can be adjusted in such a way that ground material that is still too coarse moves upwards along the outer wall of the air guide device and can reach the removal ring chamber behind this air guide device in order to then be fed directly back into the grinding chamber.

According to the invention, the receiving funnel can be designed as a receiving ring channel for the ground material leaving the area of the impact tools above the ground material to be pneumatically conveyed further in its area of largest diameter, with guide and guiding elements for controlling the ground product trickling downwards. The guide and guiding elements can simultaneously be designed as the supports for the air guiding device protruding into the interior of the rotor.

The invention also provides that a grinding material return is assigned to the receiving hopper at the lowest point. By flushing the receiving hopper with conveying air, the material is sifted; insufficiently crushed material particles collect at the bottom of the hopper and can be fed to the impact mill with the help of the grinding material feed return.

It is known to supply heat to such mills, for example for drying. For this purpose, the invention also provides for supply nozzles for a secondary gas, such as warm air, to be arranged on the mill housing surrounding the impact tools. Instead of warm air, cooling air can also be supplied or, depending on the products to be ground, inerting gases, to name just a few possibilities.

The invention also provides for the mill sections to be designed as modules screwed together. For example, the grinding material receiving space with the helical conveying air supply can be designed as a single module, the mill housing surrounding the impact tool with the grinding material supply as a single module, if necessary with a gas supply nozzle, as well as the helical discharge for the conveying air grinding material flow with shaft bearing and the flanged drive motor, each as modules. This design makes it possible to

It is possible to replace elements without wasting a lot of time if necessary.

It can be advantageous if, as the invention also provides, cylindrical, segmented baffle wall supports with outward-facing, spring-loaded holding and adjusting screws are provided. This inventive design makes it possible to adjust the grinding gap from the outside according to the respective requirements.

Further features, details and advantages of the invention will become apparent from the following description and the drawing. This shows in

Fig. 1 is a sectional drawing of the impact mill according to the invention,

Fig. 2 an enlarged section in the transition area between the hub and the air guide device inside the rotor,

Fig. 3 a partial section through the rotor with impact tools,

Fig. 4 a horizontal section through the rotor,

Fig. 5 a detailed enlargement in the area of the striking tools,

Fig. 6 a partial enlargement in the area of the impact wall with impact wall support,

Fig. 7 a horizontal view of the extraction ring space above the rotor and into the

Fig. 8 and 9 Partial sections in the representation according to

Fig. 7, with the small position of the removal openings in Fig. 8 and the large position of the removal openings in Fig. 9.

The impact mill, generally designated 1, is designed in a modular manner and has a vertically aligned rotor axis 2 with a speed-adjustable drive motor, generally designated 3, flanged on top.

At its free end opposite the motor 3, the rotor 4 is arranged on the rotor axis 2 by means of a vane or spoked wheel, generally designated 6, wherein the free end of the rotor axis 2 behind the vane and spoked wheel 6 is equipped with a hub 7 for flow guidance, which is described in more detail below.

The rotor 4 is equipped with impact tools 8 fastened in dovetail guides 5 (Fig. 5), which interact with a baffle wall 9 while leaving a grinding gap 10, as indicated for example in Fig. 3 or Fig. 5. The baffle wall 9 is made up of individual segments, indicated in Fig. 6, these segments are designated 11 and can be adjusted from the outside, namely via adjusting screws 12, with disc springs 14 being provided between the housing wall designated 13 and the segments 11 (Fig. 6).

Below the mill element consisting of the rotor and baffle wall, a funnel-shaped receiving space or receiving funnel 15 is provided, which in its upper region carries an air guiding device 17, similarly shaped to a turbine inlet, via flow-guiding spacer supports 16, whereby the inner skirt of the air guiding device, designated 17a, projects into the interior of the rotor 4 as far as the spoked wheel 6 in such a way that a flow ring space 18 is formed in connection with the hub 7. The spokes of the wheel 6 provide passage openings 19 for the air flow carrying the ground product.

It can be seen that openings 20 are provided in the funnel-shaped receiving space 15, such that conveying air for

the ground product can enter the receiving funnel 15 and the ground product trickling downwards from the grinding gap 9 can be conveyed upwards through the ring channel 18 and the openings 19 in the spoked wheel. The air inlet is shown with an arrow 22, the path of the conveying air with the ground product is shown by arrows 23 with dots.

In the upper area of the grinding gap 9 there is the grinding material feed, indicated by a corresponding nozzle 24 and an arrow 25, whereby in this area connection nozzles for a secondary gas source can also be provided, designated in Fig. 1 with 26, by means of which dry air, cooling air or inert gases can be fed into the grinding chamber/the interior of the mill.

The screw-shaped outlet of the ground product/air mixture is designated 27 in Fig. 1.

Above the spoked wheel, a wall of the ring channel 18 is provided with openings 28 that are adjustable in size, with an annular space 29 behind it, as can also be seen in Fig. 7 to 9. A sliding guide wall 31 that opens or closes the openings 28 can be moved via an adjusting screw 30; the small adjustment of the openings 28 is shown in Fig. 8.

• ·* • * ·· »ft • * • fts · · ·. ·

the large setting in Fig. 9, where the larger opening is designated 28a.

The device works as follows:

For example, ground material is introduced into the feed 24 by means of a conveyor screw and trickles from there into the grinding gap 9, is thereby crushed by the rotating grinding tools 8, the resulting ground product trickles downwards in the direction of gravity into the funnel-shaped receiving space 15.

By means of the conveying air flow 22, which penetrates into the receiving hopper 15 via the screw-shaped feed 21, the ground product is captured, swirled and conveyed through the interior of the rotor 8 past the hub 7 into the annular space 19 and from there into the screw-shaped discharge 27 and leaves the mill at the top.

The material to be ground can be carefully treated by the possibility of supplying conveying air 22 or by designing the inlet openings 20 for the conveying air in the receiving hopper 15. Heavy particles can settle at the bottom of the hopper and, for example, after opening a slide, can be removed via the opening 32 that is then created and fed back to the feed 24.

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- 12 -

Another way of returning the ground material is to classify the particles contained in the conveying air stream as they flow through the rotating spoked wheel 6 under the influence of the centrifugal force acting on them as a result of the rotation of the air stream and the axial flow component in such a way that particles above a resulting particle size (separation grain size) can reach the area of the openings 28 and are guided into the annular space 29, from where they can be returned to the grinding gap. By means of a flow guide 33 or swirling vane that can be attached to the hub 7 (Fig. 2), the incoming conveying air loaded with ground material can be given a rotation component that is intended to cause a concentration of coarser ground material particles in the outer area of the annular channel 18.

As can be seen in particular from Fig. 1, the mill 1 consists of individual modules which are secured one after the other by screw connections. The lower module contains the helical conveying air supply 21 with receiving space 15, a further module is formed by the mill housing 13 surrounding the impact tools 8 with grinding material supply 25 and secondary gas supply 26, followed by the discharge 27 with the bearing unit 33 for the central shaft 2, whereby this module finally carries the motor 3.

- 13 -

Of course, the described embodiment of the invention can be modified in many ways without departing from the basic idea of the invention. The invention is not limited to a specific type of tool design, nor to a specific design of the grinding chamber; the conveying air supply can be carried out in the manner shown, but also in any other suitable way; this also applies to the grinding material conveying air discharge 27 and the like. The design of the openings marked 19 in the impeller or spoked wheel 6 carrying the rotor 4 can also be designed differently than shown. This applies in particular to the outward-facing wall of the passage openings, which in the example shown is set at approximately 40° to the vertical, marked 19a in Fig. 2. The design of this wall in terms of its curvature or inclination can depend on the particles exposed to the centrifugal force.

Claims (12)

1. Impact mill with impact tools on a motor-driven rotor, the grinding tools interacting with a stationary cylindrical impact wall and with a grinding material feed and a pneumatic grinding product discharge, characterized by a grinding material feed ( 25 ) arranged in the upper region of the impact tools ( 8 ) in the direction of gravity, a receiving space ( 15 ) for the grinding material provided below the rotor ( 4 ) in the direction of gravity, a conveying air supply ( 22 ) for the grinding product assigned to the receiving space ( 15 ), the rotor ( 4 ) being carried by an impeller or spoked wheel ( 6 ) with passage openings ( 19 ) for the grinding product guided from bottom to top (arrows 23 ) by means of conveying air. 2. Impact mill according to claim 1, characterized in that the grinding material receiving space ( 15 ) is approximately funnel-shaped with a plurality of air inlet slots ( 20 ), the head of the funnel being provided with a fixed air guide device ( 17 ) into which the hub ( 7 ) of the drive shaft ( 2 ) of the impeller ( 6) carrying the impact tools (8 ) projects as a concentric flow divider. 3. Impact mill according to claim 2, characterized in that a coaxial centric flow channel ( 18 ) is formed by the hub ( 7 ) with flow divider on the one hand and the air guiding device ( 17a) projecting into the interior of the rotor (6 ) carrying the impact tools ( 8 ) on the other hand. 4. Impact mill according to claim 1, 2 or 3, characterized in that downstream behind the impeller ( 6 ) there is arranged a removal ring space ( 29 ) on the outer circumference of the flow channel with adjustable removal openings ( 28 ) for returning insufficiently crushed material to be ground. 5. Impact mill according to claim 4, characterized in that the discharge screw ( 27 ) for the conveying air-grinding material flow is arranged downstream behind the removal annular space ( 29 ). 6. Impact mill according to one of the preceding claims, characterized in that the receiving funnel ( 15 ) for the ground product to be conveyed further pneumatically is designed in its region of largest diameter as a receiving ring channel for the ground material leaving the region of the impact tools ( 8 ) with guide and guiding elements ( 16 ) for controlling the ground product trickling downwards. 7. Impact mill according to one of the preceding claims, characterized in that the receiving hopper ( 15 ) is assigned a grinding material return at the lowest point. 8. Impact mill according to one of the preceding claims, characterized in that supply nozzles ( 26 ) for a secondary gas, such as drying warm air, are assigned to the mill housing ( 13 ) surrounding the impact tools ( 8 ). 9. Impact mill according to one of the preceding claims, characterized in that individual mill sections are designed as modules screwed together. 10. Impact mill according to claim 9, characterized in that the grinding material receiving space ( 15 ) with the worm-shaped conveying air supply ( 21 ) as an individual module, the mill housing ( 13 ) surrounding the impact tool ( 8 ) with grinding material supply ( 24 ), the worm-shaped discharge ( 27 ) for the conveying air grinding material flow with shaft bearings ( 33 ) and the flanged drive motor ( 3 ) form individual mill modules. 11. Impact mill according to one of the preceding claims, characterized by cylindrical, segmented impact wall supports ( 11 ) with outwardly pointing spring-loaded holding and adjusting screws ( 12 ). 12. Impact mill according to one of the preceding claims, characterized in that the impact tools ( 8 ) in the rotor ( 4 ) are positioned in dovetail guides ( 5 ) and are secured by means of clamping and spacer pieces.