DK2548648T3

DK2548648T3 - Mill for comminution of painting goods

Info

Publication number: DK2548648T3
Application number: DK12004733.7T
Authority: DK
Inventors: Robert Steiger; Ulrich Steiger
Original assignee: Rematec Gmbh & Co Kg
Priority date: 2011-07-19
Filing date: 2012-06-25
Publication date: 2015-01-12
Also published as: HRP20141000T1; DE202011103394U1; SI2548648T1; EP2548648A2; EP2548648B1; PL2548648T3; PT2548648E; ES2522571T3; EP2548648A3

Description

The present invention relates to a mill for the grinding of grist, In particular wood chips. The grinder of the mil! has a rotor with a plurality of grinding elements, wherein the rotor can be driven in a grinding area about an axis of rotation, and wherein the internal wail of the grinding area cooperates with the grinding elements to grind the grist. The grinding area has a feed-in opening and a discharge opening which enable essentially radial feed-ίη and discharge of grist relative to the axis of rotation. A device of this type is known for example from DE 30 20 955 A1, which discloses that the inner wall of the drum is alternately formed from grinding tracks and sieving tracks, and furthermore an insertion opening Is provided at the highest point of the grinding area,The grist is therefore ground both on the grinding tracks and on the sieving tracks, wherein the openings in the sieving tracks form a plurality of discharge openings. A device for the grinding of granular and/or fibrous items is known from EP Q 184 489 A2f wherein In certain exemplary'' embodiments grinding takes place between the Internal ’wall of the grinding area and grinding elements and in each case a feed-in opening and a discharge opening are provided which enable the supply and removal of grist, however this is in a tangential rather than a radial dlreoflon,

On the basis of the prior art Initially mentioned, the object of the Invention is to provide a mill for the grinding of grist with an increased level of efficiency and a high throughput of grist in a short amount of time.

This is achieved by the feed-in opening and the discharge opening each being arranged in the lower region of the grinding area, by the feed-ίη, the highest point In the grinding area and the discharge opening being arranged in seggence at the circumference of the internal wall of the grinding area In the direction of rotation of the rotor and by the discharge opening being free of sieves. The axis of rotation of the rotor ;s in particular essentially arranged horizontally, in this way, the grist is transported from the feed-in opening to the discharge opening via the highest point In the grinding area. The arrangement of the feed-in opening and the discharge opening in the lower region of the grinding area means that these are arranged in the lower two quadrants of the interna! wall of the grinding area, and therefore the upper two quadrants of the internal wall are available to cooperate with the grinding elements to grind the grist. The force pressing the grist on the interna! wail of the grinding area is therefore caused by the centrifugal forces generated by the rotation of the rotor, which acts both on the grinding elements and on the grist which is moving. If the grist slows when moving along the internal wall of the grinding area, at least in the upper region of the grinding area gravity acts on the grist such that this is moved in the direction of the grinding elements where it is accelerated again in a circumferential direction, in contrast to this, in mills which principally transport the grist through the lower part of the grinding area it is easier for larger unwanted collections of grist to form at the lowest point of the grinding area in particular, as both the centrifugal force and gravity move the grist there. This is why a sieve is arranged in the lower region of the grinding area in many machines of this type, which sieve, on the one hand, displays a grinding effect together with the grinding elements and, on the other hand, ensures that insufficiently ground grist does not leave the grinding area, in contrast to this, the relatively long path between the feed-in opening and discharge opening via the highest point in the grinding area in accordance, with-#® invention enables the grist to be ground to the desired size before if reaches the discharge opening. The discharge opening can therefore be designed without a sieve, which enables all or nearly all of the grist which Is in the region of the discharge opening to be discharged through the discharge opening. This is further strengthened by the fact that the discharge opening is in the lower region of the grinding area, so that, In addition to the centrifugal forces, gravity also moves the grist from the grinding area to the discharge opening. The sieve-free discharge opening has the advantage that it cannot be blocked by the grist, thereby enabling problem-free and maintenance-free operation.

In particular, the feed-in opening in the grinding area is provided directly after the discharge opening in the direction of rotation of the rotor.

The grist is carried along by the grinding elements as soon as it is fed into the grinding area through the feed-in opening and pushed against the Infernal wall of the grinding area jbf the centrifugal force. The grinding of the grist is achieved by the difference in speed between the grist and the grinding elements and the friction induced as a result of this, in particular, the mill is designed such that daring the grinding process the grist Is transported through the grinding elements from the feed-in opening via the highest point within the grinding area and then dispensed through the discharge opening.

In one exemplary embodiment of the .invention, the feeddn opening and the discharge opening are also arranged in the same position in an axial direction relative to the axis of rotation of the rotor. In particular, the feed-in openings and/or the discharge openings can extend over the entire width of the grinding area in an axial direction. A design of the feed-in opening of this type enables an even supply df grist In all regions of the grinding area, and a design of the discharge opening of this type enables the safe discharge of all grist from the grinding area alter passing along the internal wall of the grinding area.

The discharge opening is advantageously arranged on the essentially lowest point of the grinding area. This has the advantage that gravity has the optima! effect or the gnst in order to remove it from the grinding area. in a preferred exemplary embodiment, the angle of the feed-in opening to the discharge opening about the axis of rotation In the direction of rotation is more than 270°, This results In a long conveyance path along the internal wail of the grinding area and therefore a better grinding of the grist. in particular, the grinding of the grist Is predominantly or exclusively carried out between the grinding elements and the internal wall of the grinding area. This is different to conventional mills in the prior art in that the grinding is additionally also carried out between grinding elements and sieving elements which are attached above the discharge opening. In particular, the grinding of the grist is carried out between ribs on the internal wall and the grinding e'ements.

The feed-in opening is advantageously arranged in a lower quadrant of the internal wall. Furthermore, in particular the discharge opening is advantageously arranged in a lower quadrant of the internal wall

In one exemplary embodiment, the grinding area only has one feed-in opening find only one discharge opening, in this way, a defined supply and discharge of grist can be achieved, by means of which a predetermined, even grinding result can be achieved, namely a certain size of the components of the grist which Is discharged through the discharge opening.

The mill is advantageously designed such that almost all of the grist or at least the majority of the grist leaves the grinding area through the discharge opening before the completion of a: full cycle, in this way, the pathway of the grist m the grinding area is dearly defined and an even and consistent grinding of fhe grist can be achieved;.

In one embodiment, the grinding area has an essentially cylindrical form about the axis of rotation of the rotor. This enables an advantageous interaction with the grinding elements of the rotor. In other exemplary embodiments, however, it Is also possible that the grinding area is increased or decreased In certain areas, in order to achieve no or a lower grinding effect or a greater grinding effect In this region. A plurality of grinding elements are advantageously mounted in parallel in an axial direction on the rotor. This plurality of grinding elements is further also advantageously mounted on a plurality of mounting points in the circumferential direction of the rotor, such that, overall, a high number of grinding elements are advantageously mounted on the rotor in an even manner and can cooperate with the internal wall of the grinding area to grind the a rist. V*.....

In a preferred exemplary embodiment, the grinding elements are each rotatably mounted on an axis which extends in an axial direction and at a radial distance to the axis of rotation of the rotor. An axis of this type enabled the simple mounting of a plurality of grinding elements which move about said axis.

In one exemplary embodiment, the axes of the grinding elements are held by plates arranged on the rotor, the perpendicular of which plates is the axis of rotation of the rotor. These plates are in particular attached to one another by means of bolts which extend in an axial direction. 1 he grinding elements are advantageously knives; hammers, clubs or sawing elements, In some exemplary embodiments, combinations of the grinding elements Moated above can also be used to achieve the desired grinding result.

In a preferred exemplary embodiment, a forced feeder is provided which feeds the gnst through the feed-in opening in a radial direction. The fact that the feed-in opening is arranged in a lower region of the grinding area enables the forced feeder to overcome the effect of gravity, wherein the amount of grist fed in can, at the same time, be determined precisely. Alternatively, blowers or other means of conveyance can also be provided.

In a preferred exemplary embodiment the forced feeder is a screw conveyor, A screw conveyor enables a continuous and defined feeding in of grist through the feed-in opening. The defined amount of grist in turn has an effect on the grinding of the grist between the Internal wall of the grinding area and the grinding elements, such that by regulating the amount being fed in through the screw conveyor the grinding result can be directly regulated and/or set

The internal wall of the grinding area advantageously has several ribs arranged in parallel, at an angle to the circumferential direction, which ribs are arranged at an angle of 30 to 80° to the circumferential direction and in particular are arranged at an angle of approximately 42.5° to the circumferential direction. The narrower the angle of the ribs to the circumferential direction is, the lower the grinding performance, as then transportation of the grist in the direction of the ribs occurs to a great extent and the grinding transfer via the ribs occurs to a lesser extent. On the other hand, a narrow angle has the advantage that a seif-cleaning effect occurs, in other words, no grist collects In the ribs. In the angle range defined, there Is a compromise between these two properties, wherein the most advantageous results can be achieved at an angle of approximately 42,5°.

In an advantageous exemplary embodiment, the ribs are each arranged area by area inclined In the circumferential direction with angles with opposing signs. This enables a transport of the grist to be carried out in an opposing axial direction relative to the rotor in each case in these areas such that the grist is overall not essentially displaced on the Internal waft in an axial direction when conveyed, but merely a type of oscillating movement In én axial direction is carried out.

The interna! wall of the grinding area advantageously has exchangeable grinding plates, wherein the ribs are arranged on the grinding plates. On the one hand, this has the advantage that the grinding plates can be formed from a harder material and can therefore withstand higher loads. On the other hand, it also has the advantage that the grinding plates in the mill can be exchanged as required, in order to achieve an optimal grinding result for various grists.

The entire internal wall of the grinding area is advantageously formed by grinding plates. In this way, the entire internal wall of the grinding area contributes to the Grinding process, wherein the only areas where no grinding process takes p>ac 5 are the feed-in opening! and the discharge opening,

In one exemplary embodiment, a sieve Is provided at a distance from the discharge opening, which sieve is designed to sieve the material discharged through the discharge opening. This sieve is arranged such that no grist residue can form back as far as the discharge opening, in other words, at a considerable distance from the discharge opening. This ensures, on the one hand, that the sieve does not prevent the flow of grist through the discharge opening, and, on the other hand, that only sufficiently ground grist Is provided as an end produce

In particular, the material which does not pass through the sieve Is fed back to the feed~in opening. This means that this material can be fed into a further grinding process and will be further ground accordingly until it has attained the desired size

The object of the invention is also achieved by a mill In accordance with the preamble of the Independent claims, in which the grinding of the grist is carried out exclusively between the grinding elements and ribs on the internal wall of the grinding area, wherein the discharge opening is sieve-free. In this way, a mill of this type can also prevent sieves from blocking a discharge opening, wherein a high and even grinding performance can nevertheless be achieved by grinding between the grinding elements and the internal wall of the grinding area. The above mentioned mill can also be combined with all of the above mentioned features.

Finally, the invention also relates to a method for the grinding of grist in a mill with a grinder having a rotor with a plurality of grinding elements, wherein the rotor is driven in a grinding area about an axis of rotation, and wherein initially the grist is fed through a feed-in opening in the lower region of the grinding area, then it is ground by means of cooperation of the internal wall of the grinding area and the grinding elements while it is transporten from the feed-in opening via the highest point in the grinding area to a discharge opening, and wherein finally the grist is discharged in an essentially radial direction through the discharge opening in the lower region of the grinding area, wherein the discharge opening Is fee of sieves.

In particular, the method Is characterised in that the grist is primarily discharged through the discharge opening before the completion of a full circle In the grinding area. The grist 1s advantageously force-fed through the feed-in opening in a radial direction, in particular through a screw oorifeyor.

Furthermore, the grinding of the grist is advantageously exclusively carried out between the grinding elements and the Internal wai! of the grinding area.

An advantageous exemplary embodiment of the invention is described below with the aid of the figures,

Figure 1 shows a sectional view of the mill in accordance with the invention from the side.

Figure 2 shows a further sectional view of the ml in accordance with the invention from the side, wherein this sectional view is orthogonal to the sectional view of Figure 1;

Figure 3 shows a region of the nternal wall of tne ml in accordance with the invention.

Figure 1 shows a cross section of 1 in accordance with the invenioRv in particular a hammer mill, wherem a rotor 3 is arranged inside a cylindrical grinding area which is delimited by an interna! wall 2. The rotor 3 has a centra! rotor shaft 4 which can be driven about an axis of rotation R (see Figure 2). The rotor shaft 4 and the axis of rotation R extend perpendicular to the plane of the drawing in Figure 1.

The rotor 3 has a plurality of grinding elements 5 which cooperate with the internal wall 2 to grind the grist in the grinding area. The grinding elements 5 also have the function of transporting the grist. The grinding elements 5 are pivotably mounted on axes 6 which extend parallel to the rotor shaft 4, in other words, in an axial direction of the rotor 3 and are arranged at a distance from the rotor shaft 4* In particular, the axes 6 are evenly distributed around the circumference of the rotor 3 and are each at the same radial distance from the refer shaft 4. The rotor 3 has at least two plates 7 which are arranged on the rotor shaft 4 and in which the axes 6 are arranged. The plates 7 are In particular designed as circular plates, the perpendicular of which is the axis of rotation R and in the centre of which the rotor shaft 4 is arranged. The plates 7 are attached to one another by means of bolts 8 which extend in an axial direction of the rotor shaft 4.

The Interna! wall 2 of the grinding area essentially corresponds to the internal wall of a hollow cylinder which is arranged about the axis of rotation R of the rotor 3. The Internal wall 2 is formed by a plurality of grinding plates 9 which are provided with ribs 10 (see Figure 3), The grinding elements 5 are each arranged such that they can grind the grist in cooperation with the grinding plates 9 on the internal wall 2 of the grinding area.

The rotor shaft 4 is driven in a clockwise direction, as shown by the arrow in Figure 1. The grinding area has a feed-in opening 11 which is arranged in the lower left quadrant of the Infernal wail 2 of the grinding area. The feed-in opening 11 is a direct opening into the grinding area and does not have a sieve or any similar elements. Grist is brought into the grinding area through the feed-in opening 11 by means of a forced feeder 12 in the form of a screw conveyor. The feed-in direction of the grist into the grinding area Is in particular radial relative to the axis of rotation R of the rotor 3. The grist reaches the gap between the rotor 3 and the internal wall 2 and Is carried along the Internal wall 2 in a clockwise direction by means of the grinding elements 5. The grist is therefore conveyed from the feed-in opening 11 In the direction of the highest point in the grinding area. The centrifugal forces bring the grist into contact with the internal wall 2 and cause it to be ground by the grinding elements 5 cooperating with the internal 'wall 2. Starting from the highest point in the grinding area, the grist Is further transported along the upper right quadrant and the lower right quadrant of the Internal wall 2 of the grinding area until it ultimately leaves the grinding area through a discharge opening 13.

The discharge opening 13 is arranged on the lowest point of the grinding area such that the grist leaves the grinding area by the effect of gravity Accordingly, the discharge opening has a relatively large cross-section and has no sieve or suchlike in it. In this way, the grist is conveyed from the feed-in opening 11 approximately over 315° about the axis of rotation R along the internal wall 2 of the grinding area by means of the grinding elements 5 until if leaves the grinding area through the discharge opening 13. Only negligible or small parts of the grist are conveyed along the pathway between the discharge opening 13 and the feed-in opening 11. As can be seen in Figure 1, the discharge opening 13 and the feed-in opening 11 are close to one another, so that the grinding route between the feed-in opening 11 and the discharge opening 13 in the clockwise direction is formed as long as possible.

After the discharge opening 13, the grist fails through a shaft 14 and if necessary is guided through a sieve (not shown), so that unwanted large constituent parts of the grist can be fed back into the forced feeder 12.

Figure 2 also shows the mill 1 in a side sectional view, wherein the rotor shaft 4 now extends horizontally In the drawing plane, A drive 15, in particular an electric motor, is provided to drive the motor shaft, which drive 15 is connected to the rotor shaft 4 by means of a coupling 16. The rotor shaft 4 is mounted on rolling bearings 17, 18 on both sides. A plurality of the pistes 7 are arranged at a distance from one another in an axial direction on the rotor shaft 4, wherein one central and one external plate 7 are thicker than the remaining plates 7. The plates 7 are connected to the bolts 8 which have a plurality of indentations to fix the plates 7. The individual segments of the bolts 8 are connected to one another by means of a long screw.

The grinding elements 5 are mounted on the axes S which are held by the plates 7, Distance holders are provided between the grinding elements 5, in order to keep the grinding elements in a defined axial position. The distance holders can be integrally formed with the grinding elements 5.

Finally, Figure 3 shows another section of the Internal wail 2 of the grinding area, in which it can be seen that the internal waif 2 Is formed by several grinding plates 3 which are mounted using screws. The screws are provided in recessed openings in the grinding plates 9. The Individual grinding plates 9 each have ribs 10 which extend at an angle to the circumferential direction, In this case, at an angle of 42.5°. This angle provides both a good grinding performance and a self-cleaning action of the grinding plates 9. in a preferred embodiment, the grinding plates 9 can each be arranged In a different alignment, in other words, in the present case the central grinding plate is designed such that its ribs 10 extend at an angle with the opposite sign to the other two grinding plates. This can prevent a conveying effect of the grist front occurring in an axial direction.

Alternatively to designing the internal wall 2 with grinding plates 3, the ribs 10 can also be provided as integral parts in the internal wall of the mill. The advantage of the design with grinding plates 9, however, is that the grinding plates δ can easily be exchanged and therefore various designs of ribs 10 for various grinding applications can be provided and worn grinding plates can be replaced

The mill is particularly suitable for grinding moist wood chips, wherein it is not a mill for fine grinding but rather a mill far pre-grinding. The wood chips are subsequently passed on for example for further processing in a dryer. The rotor is in particular driven at 1,500 rotations a minute.

The distance between the individual grinding elements & In the form of hammers e approximately 3 mm in the axial direction.

The grinding plates 9 are made but of hardened material and can be exchanged in the mill 1.

The Internal wail 2 is in particular completely covered With grinding elements 9. The fact that the discharge opening 13 is at the bottom of the mill means that no vacuuming of the mil! is necessary. The fact that the discharge opening 13 is sieve-free means that it can be smaller p design than a discharge opening 13 with a sieve which is to provide a corresponding discharge output A sieve-free discharge opening 13 therefore means that a higher proportion of the internal wall of the grinding area can cooperate with the grinding elements 9. Mills which have sieves in the discharge opening also rapidly show signs of wear in the sieves and require more maintenance as a result of this.

The grinding elements 5 are in parfcUar designed as hammers, namely as metal plates with a perforation, which are placed onto the axes.

Claims

A mill (1) for comminuting grinding materials, especially of wood chips, comprising a grinder showing a rotor (3) having a plurality of grinder elements (5), wherein the rotor (3) can be driven about a rotary axis (R) in a grinder space , wherein the inner wall (2) of the mill space interacts with the mill elements (5) to comminute the grinding material, and wherein the mill space has a supply opening (11) and a drainage opening (13) allowing a substantially radial supply relative to the axis of rotation (R). and discharge of grinding material, characterized in that the supply opening (11) and the drainage opening (13) are each provided in the lower area of the mill space, that the supply opening (11), the highest point of the mill space and the drainage opening (13) are provided sequentially on the perimeter. of the inner wall (2) of the mill space in the direction of rotation (R) of the rotor (3), and that the drain opening (13) is without a sieve.

A mill according to claim 1, wherein the mill (1) is constructed such that during the milling process the milling goods are transported by means of the milling elements (5) from the supply opening (11) via the highest point inside the mill space and then discharged through the discharge opening (13).

A mill according to claim 1 or 2, wherein the supply opening (11) and the discharge opening (13) are provided at axially the same height with respect to the axis of rotation (R) of the rotor (3).

A mill according to any one of the preceding claims, wherein the discharge opening (13) is provided at the substantially deepest point of the mill space.

A mill according to any one of the preceding claims, wherein the angle of the axis of rotation (R) from the supply opening (11) to the discharge opening (13) in the direction of rotation is more than 270 degrees.

A mill according to any one of the preceding claims, wherein the comminution of the painting material takes place exclusively between the grinder elements (5) and the inner wall (2) of the grinder space.

A mill according to any one of the preceding claims, wherein the mill space has only one supply opening (11) and only one discharge opening (13).

A mill according to one of the preceding claims, wherein the mill (1) is designed such that the next whole milling material or at least the predominant part of the milling material leaves the mill space through the discharge opening (13) before completing a full cycle.

A mill according to any one of the preceding claims, wherein the grinder elements (5) are each rotatably fixed on an axis (6) extending in axial direction and at a radial distance relative to the axis of rotation (R) of the rotor (3).

A mill according to any one of the preceding claims, wherein a forced feed (12) is provided which feeds paint in a radial direction through the feed opening (11).

A mill according to claim 10, wherein the forced feed (12) is a transport auger.

A mill according to one of the preceding claims, wherein the inner wall (2) of the mill space exhibits several parallel, circumferentially oriented ribs (10) disposed at an angle of 30 to 60 degrees relative to the circumferential direction, and in particular at an angle of about 42.5 degrees to the perimeter.

A mill according to any one of the preceding claims, wherein at a distance from the deflection opening (13) a screen is provided which is designed to screen material which is passed through the deflection opening (13).

A mill according to claim 13, wherein the mill (1) is designed to supply the material which does not pass through the screen to the feed opening (11) again.

A method for comminuting grinding materials in a mill (1) comprising a grinder showing a rotor (3) having a plurality of grinder elements (5), wherein the rotor (3) is driven about a axis of rotation (R) in a grinder space, and wherein the paint is first supplied through a supply opening (11) in the lower area of the mill space, then comminuted by interaction between the inner wall (2) of the mill space and the mill elements (5), while it is transported from the supply opening (11) via the highest point of the mill space to a drain opening. (13), and wherein the milling material is finally guided in a substantially radial direction through the drain opening (13) located in the lower region of the mill space, the drain opening (13) being without a sieve.