EP1812164A2

EP1812164A2 - Crushing element and mills with grinding bodies, mixers, extruders and a pressing worm provided with said crushing elements

Info

Publication number: EP1812164A2
Application number: EP05794312A
Authority: EP
Inventors: Ulrich c/o Welldone BECH
Original assignee: Welldone Weartec NV
Current assignee: Welldone Weartec NV
Priority date: 2004-10-21
Filing date: 2005-10-21
Publication date: 2007-08-01
Also published as: CA2585070A1; US20090045278A1; WO2006043162A2; WO2006043162A3

Abstract

The invention relates to a crushing element for mills, mixtures and worms used, preferably, for grinding and treating paper pulp and plastic materials containing ceramic fillings and other fibrous materials such as raw lignite, beet chips and the similar. The crushing elements comprise at least two fixing elements which can be provided with undercuts (44), beads and/or corners and arranged on a fastening side (36) opposite to a working surface (38) for fixing the crushing element (41) in corresponding holes of a supporting part. Said crushing elements are mountable on the rotors of high-speed refiners. The rotors comprise annular sectors consisting of a plurality of individuals crushing elements. Different tasks are assigned to said annular sectors. A middle sector is made of metal carbides which are tenaciously embedded in such a way they are fixed, high-temperature resistant and exhibit emergency running properties when a rubbing of a grinding disk occurs. In order to provided a slightly smaller working space in the area of said sector, the adjacent sectors are protected against rubbing and are formed by the modular and low-cost crushing elements (lamellar bodies) made of a ceramic material or compressed carbon fibres. Said lamellar bodies are obtainable by the accurate serial production (PIM-powder injection moulding) and compression in a sieve-like supporting plate are optimally shaped for each user. The lamellar bodies are easily and rapidly interchangeable.

Description

Mahlelement, and grinding media mills, mixers, extruders and press screws with such grinding elements

Object of the invention:

The present invention relates to a grinding element, for example for mills, mixers, extruders and press screws.

State of the art

Mills and mixers are built in large numbers and with different grinding plates for different end products and different intermediate stages in a row. By default, the grinding plates on the grinding disc are made of a chill casting alloy, which are given sufficient hardness by chromium carbides to meet the requirements for wear. With conventional machines and when processing pure wood pulp at medium speeds, this results in satisfactory operation with revision intervals of 6-10 months. The quality of the milled fibers is clearly determined by the ribbed geometry of the grinding plates, which provide a spiral flow of material across the fins to the outlet. It creates a pumping or pressing action. This effect is primarily sought in press screws and extruders. At the same time an intimate, uniform mixing of the filled substance is always achieved. Because this is composed heterogeneous.

For the production of fine papers, a grinding down to very small fiber diameters and lengths is required. This requires a small working gap of the order of a few tenths of a millimeter. In practice, grinders are used which work with rollers, cones or grinding discs. For grinding disks, where the material flows radially from the inside to the outside, the wear takes place mainly in the outer third due to the higher peripheral speeds. However, the scarcely wearing, inner parts of the grinding disc are decisive for the distance between the grinding disks of rotor and stator, so that a material wear in the outer sectors of the grinding disc can not be compensated by repositioning the axle. When resetting the axis namely threatens a rubbing of the refining plates. This danger is particularly great when starting up and shutting down the machine if the pressure and material flow conditions are not yet stable.

For economic and ecological reasons, more and more demands are made for incorporating existing materials and return material from production into the mixture of materials. As a result, fillers of a ceramic nature are often to be processed, which significantly increases the wear. To solve this problem harder grinding media are often used. However, these are extremely sensitive to light scrapers. If the grinding media in the outer working edge area only Slightly worn by a few tenths of a millimeter, so in the main work area for the grinding of the fibers and mixtures a too large working gap. The performance of the machine decreases, the quality of the product as well. Extremely accurate, fast-reacting controls can improve the utilization of grinding discs down to the geometric limit.

For fast-running machines with internal pressure, the working gaps are so small that they are within the range of the elastic reactions of the machine: Smallest changes in the vibration behavior of the grinder caused by changes in the material properties can therefore cause severe wear of the grinding disks or even the destruction of the machine.

From a process engineering point of view, it is possible to drive up the machines in their daily output through the narrowest working gap and increased speed by using sophisticated controls and control loops. An increased grinding performance with reduced power consumption of up to 20% is possible. The price is the need for frequent change of Mali Ischeiben, as the peak benefits are achieved only in a short period of service life. Conventional grinding discs consist of a carrier and arranged on the support lamellar grinding bodies made of chilled cast iron. The production of the chill-cast media requires a mass grinding of the fin surface prior to installation. However, this results in sharp working edges, which do not allow an optimal Mahlerresultat at the beginning of the grinding process. Only after an 'entry phase' (edge rounding) an optimal grinding result is achieved. If increased wear is accepted, grinding performance and product quality decrease rapidly.

Object of the invention

Object of the present invention is to propose a refining element, which has a longer service life. Yet another goal is to propose a grinding media with a grinding element, which delivers the desired grinding quality from the beginning. Another goal is to propose a roller, cone or grinding disc grinder, which is inexpensive to produce and has a long service life. Still another object is to provide machines, in particular grinding devices such as refiner for paper, extruders for plastics and ceramics, press worms for wet fibers, lignite, peat, beet pulp etc., which have long service intervals. It is desirable if it can be dispensed with particularly expensive and expensive controls.

Subject of the invention

According to the invention the object is achieved in that at least two fastening elements are provided on the opposite surface of the working surface for fixing the grinding element in corresponding holes of a supporting body, which have undercuts, beads and / or corners. These grinding elements have the advantage that the Fixing elements allow a secure attachment to a support body, so that even large lateral forces can be absorbed. In particular, the grinding elements allow a modular construction of grinding disks, so that the properties of the individual grinding sectors can be better tuned than in known grinding disks with chilled cast iron plates.

Through holes are advantageously provided in the elements, which holes can be used for injecting water or dewatering. As a result, the resulting water from the decomposition of fibers can be removed quickly. Conveniently, the holes are formed as slots with diffuser-like outlet.

The proposed novel grinding elements have the advantage that the grinding elements can be produced in the powder press molding process or preferably in the powder injection molding process (PIM). This makes it possible to produce the grinding elements inexpensively. The grinding elements are expediently surface-compacted (by duplex coating: diffused ion-nitriding + IBAD, ion beam-assisted deposit of WC-Co, TiN, DLC etc.). This allows the production of very resistant grinding elements with high temperature resistance.

According to a preferred embodiment, a first type of grinding element is made of high temperature resistant materials. These may be, for example, grinding elements made of cemented carbide and mixed with high-temperature carbides, high-temperature (mixed carbides, nitrides or borides or mixtures thereof with a cobalt matrix, preferably the first type of grinding element made of hard metal with WC, TiC, SiC-SiN, if appropriate also borides or similar hard phase formers with eutectic matrix type Ni / Co-Cr-V-Nb-B-Si-C. Such grinding elements are characterized by a good high temperature resistance of better than 2000 ⁰ C, preferably better than 2500 ⁰ C, and especially preferably better than 2800 ⁰ C.

Advantageously, a second type of grinding element is provided, made of ceramic materials. This second type can be made of inexpensive materials. One possible composition of the refining element is, for example, Si-Al-Zr oxide. Alternatively, the second type of grinding element can be made of pressed carbon fibers, optionally with DLC coating.

The subject matter of the present invention is also a grinding body with grinding elements according to the invention, which is characterized in that drilling or punching holes are provided in the supporting body, and that the grinding elements are received in a form-fitting manner with the fastening elements in the drilling or punching holes. The fit can be done by encapsulation with materials that have a lower melting point than the grinding elements and Supporting body resp. Support plate. Such grinding media have the advantage that the grinding elements can be exchanged quickly by heating them. Also, the grinding elements composed of individual grinding elements can be optimized in geometry and material properties. As a result, thermal residual stresses can be avoided, for example, on the support surfaces. The preparation of the grinding elements with the fastening elements can be made of high-strength sintered materials, in powder molding, preferably powder injection molding (PIM). These (single) grinding elements are conveniently fastened by means of their fasteners on perforated support plates form-fitting manner. The grinding elements can therefore be changed easily and quickly. Conveniently, arranged in the drill or punch holes fasteners are molded with plastic, glued or soldered. The encapsulation of the fasteners has the advantage that they are firmly anchored in the support body.

Advantageously, the first type of grinding element in the support body is inserted by co-sintering of grinding element and carrier, preferably by two-step pressing of grinding elements and supporting body in the same mold (powder molding or PIM process). It is expedient, if the first type of compacted refining element is incorporated on a supporting body of such geometry, that it is possible to weld / staple to working surfaces of apparatus without extending the heat affected zone into the refining element.

Preferably, the fasteners are inserted with beads and / or corners by cold pressing in the holes of the support body low-stress. This embodiment has the advantage that the fasteners can not solve their fixings.

A preferred embodiment provides that grinding elements of the first and second types are provided on the support body. This has the advantage that the different areas of a refining plate can be equipped with different grinding properties. Preferably, a plurality of refining elements of the same type are each adjacent to each other to form sectors with certain grinding characteristics, or the plurality of refining elements form working edges with the same characteristics. Advantageously, the grinding element in the material flow direction has at least two sectors occupied by grinding elements of the first or second type.

Preferably, a plurality of individual grinding elements is arranged on carrier plates, which correspond in size to the size of conventional chilled cast iron plates. This has the advantage that the carrier plates can be used with the refining elements in place of the conventional chill grinding plates. Although the grinding elements according to the invention are arranged directly on a housing wall, for example, of an extruder or on a rotor carrier disk can, the use of an additional support plate or a support body has the advantage that the grinding elements can be pre-assembled on these. In addition, the grinding elements can be replaced with a lower Aurwand, because the carrier plates with the grinding elements can be placed directly in an oven to melt the solder or other materials with relatively low melting point, which can be used for releasably securing the grinding elements to the support plate ,

According to an independent aspect of the invention, a first sector is occupied by grinding elements which ensure "emergency running properties." The surface of this first sector preferably projects beyond the surfaces of the adjacent sectors by a certain distance The first sector can be detached from the grinding elements of a second, preferably adjacent, sector, so that the first sector forms a so-called scraper protection, thereby avoiding grinding elements or entire refining plates being destroyed if they should touch during operation. In a grinder between the first grinding element and a mating surface has a smaller working gap than between the other grinding elements and the mating surface, the mating surface can also be m be occupied Mahlelemente, or be formed by a stationary wall with or without structuring (slats or the like).

It goes without saying that in the various uses of the refining elements, for example in extruders, screw extruders, on grinding plates of refiners, each one sector of refractory refractory elements serves as anti-stripping. This means that there is a smaller working gap in the area of this sector, so that other sectors are protected with grinding elements.

The runflat grind element (multiple like elements may be grouped into sectors) is preferably made of a friction wear resistant material having a fine-grained structure yet having residual toughness. The grinding element of the first type can be made with a greater strength than grinding elements of the second type. However, it is also conceivable to effect the settling of the first grinding elements by appropriate design of the base (supporting body). However, it is also conceivable to produce the runflat grind element or sectors formed therefrom from pressed carbon fibers.

According to a preferred embodiment, the other grinding elements of the second and third sector may consist of low-cost ceramic elements. It can do that first described grinding element be the middle sector and the surface of the first grinding element be deposited from the surfaces of the other two (second) grinding elements. This embodiment is particularly suitable for "high-speed refiner" paper mills with grinding discs with optimized to the desired functions annular sectors. Advantageously, the middle sector is offset from the surfaces of the inner and outer sectors. The middle sector has "runflat" properties and therefore has the function of anti-squeal protection, which prevents the other sectors from sticking together during operation.

A particularly advantageous embodiment provides that the grinding body has a carrier plate on which a plurality of first and / or second grinding elements is arranged. This carrier plate may correspond to the size of known integral chilled cast segments. This is a completely different construction compared to conventional grinding media in which the integral chilled cast segments are divided into a plurality of individual grinding elements. This allows completely different production methods for the production of grinding media resp. Use grinding elements, such as powder injection molding (PIM). By this manufacturing method, the fastening elements can be molded directly to the grinding elements. The individual grinding elements on the rear side (i.e., opposite the working surface) advantageously have fastening members which can be positively connected or connected to the supporting body. Thus, the pressure-loaded surfaces can remain low-stress. As fasteners come bolts, hollow pins, screws o.a. in question. These grinding elements have the advantage that the particularly workable outer zone is 100% usable: i. There are no more screw holes for attaching the grinding elements in the work surface - this in contrast to conventional grinding media with chilled cast iron plates.

Preferably, the fastening members are dovetail-shaped feet, which are received in holes of the carrier body, preferably round holes with a top conical bore. These have the advantage that they can be encapsulated in a defined position at low heat with plastic - or soldered - and thus can be firmly anchored in the support body. The feet may be polygonal shaped to limit horizontal stresses in the plastic material of the Tragkörper- material. The support body can in turn have precise cylinder hollow pins, which can anchor the fastening elements, for example in a rotor, but at the same time allow a quick exchange. Likewise, in the case of supporting bodies which only have to protect the outer edges of rotors or screws, molded tabs are possible, which are fastened to the rotor with short, detachable weld seams.

The sectors are expediently covered with a plurality of grinding elements which have surface structures as are well known to the person skilled in the art. For example, in the papermaking process surface structuring of the sector parts, eg ribbed Geometries with channels of a few millimeters depth ensure the digestion of pulp into the thinnest possible fibers and the outflow of the substance. Such trained grinding elements can also be referred to as lamellar elements or lamellar body. Preferably, these lamellar elements of the sectors are produced by the powder injection molding process (PIM) or by powder pressing, if necessary hot isostatic pressing (HIP: hot isostatic pressing).

Through the use of PIM, it is possible to optimize a three-layer composite body and cost-effectively in series: Only the layer directly under the coating (TiN, DLC, etc.) is expensive carbide sintered as a perfect substrate. The base is e.g. formed by hardenable, ferritic chromium steel (17-4), co-sintered with the hard metal .. This has the additional advantage that such a composite body can also be connected by welding to a support plate.

The production of sector parts by powder injection molding or powder pressing has the great advantage that the edges of the surface structures can already be produced in an optimum shape. As a result, mills with such grinding media already from the beginning bring an optimal result. On the other hand, conventional chill plates made of chilled cast iron, whose surface structures are sharp-edged at the beginning, have to shrink first and therefore only after a certain number of operating hours produce an optimum result.

In the context of the present invention, different material combinations are possible for the individual sectors of grinding bodies: in the presence of three (annular) sectors, these can be produced in the material flow direction (from inside to outside), for example, from the following materials:

Chilled, carbide, ceramic or chilled, carbide, carbon fiber or ceramic, carbide, carbide or ceramic, carbide, carbon fiber, or carbide, carbide, carbon fiber or chilled, carbide, carbon fiber. Further combinations are conceivable.

Advantageously, the dovetail-shaped, optionally angular feet received in the holes are encapsulated with plastic or glued or soldered (or directly co-sintered with liquid phase, see above). This has the advantage that the anchoring can be done positively and very quickly. The removal of the grinding elements can be done by heating the grinding media. For three-layer composite bodies, the welded connection of the carrier plate can be released.

The grinding elements are expediently designed as lamellar bodies with surface structuring, produced by powder presses or PIM.

Advantageously, the outer sectors are designed as carrier plates with martensitaushärtenden or outsourced duplex steels - precisely drilled as a screen plate segment according to known technology. In principle, the carrier plate can also be produced as a stamped part (FIG. 21c) with cold-pressed tapered holes. The advantage lies in the favorable expansion coefficient and in the much higher yield strength with sufficient corrosion protection, sufficient toughness can be adjusted. This allows weight reduction and thus lower centrifugal forces and higher working speeds.

On the rotor, a support plate may be arranged with holes and screw holes for knobbed feet. Screw holes allow a direct recording of grinding resp. Slat elements that can be changed without rotor removal.

The stator-side grinding media can be provided with holes for controlling the water content. According to one embodiment, the lamellar bodies (grinding elements) may have holes in the dimpled feet, which may permit water injection or drainage without losing active surface (FIGS. 18, 19). It is possible to press the holes in slot form without additional effort, which offers procedural advantages. Behind the slot, a diffuser-like opening of the holes can be pressed, which avoids blockages.

The subject matter of the present invention is also a mill, in particular high-speed refiner for paper stock, with grinding elements according to one of claims 1 to 31. The carrier plate can be connected to the rotor by cylindrical hollow pins (FIGS. 6-10) or by a detachable welded connection. In this case, tabs can allow points for detachable welded joints, which avoid a heat affected zone, in the area of the knobbed feet of the elements.

The stator-side grinding media can be provided with holes for controlling the water content. According to one embodiment, the lamellar bodies (grinding elements) can have holes in the dimpled feet, which can allow water injection or drainage without losing active surface.

The rotor can be designed as a disk, cone or roller.

Another object of the present invention is a mill with grinding bodies with radially different sectors, which is characterized in that an annular Sector is made of high temperature resistant materials and has "emergency running properties". Advantageously, the gap width between the opposing grinding elements with emergency running properties is smaller than the gap width between the other grinding elements. This has the advantage that the sector with runflat properties prevents a sticking together and thus damage to the other sectors. This results in much longer service life of the grinding plates and also better quality results for the ground product.

The invention will now be described by way of example with reference to the figures. It shows:

Figure 1 Schematically a plan view of a traditional trained as a disc

Rotor with thereon, conventional grinding elements;

FIG. 2 shows the disk rotor of FIG. 1 in longitudinal section;

Figure 3 Schematically the known rotor of Figure 2 on an enlarged scale and in section (prior art).

Figure 4 shows a first embodiment of a disc rotor with a support plate and arranged thereon inventive grinding elements in section;

FIG. 5 shows a section of the rotor disk of FIG. 4 on an enlarged scale

Support plate for lamellar elements, possibly attached to the rotor with cylindrical hollow pins

FIG. 6 Schematically and in longitudinal section, on a supporting body. arranged,

Slats having meal with nubs feet, which have undercuts;

Figure 7 Schematically and in cross-section the refining element of Figure 6;

Figure 8 The refining element of Figure 6 in plan view;

FIG. 9 shows a second exemplary embodiment of a grinding element according to the invention with (water) passages;

FIG. 10 shows a section through the refining element of FIG. 9 along the line AA;

Figure 11 Schematic arrangement of grinding media for any mills: Double-flow refiner with housing and a conical rotor; Figure 12 schematically in section a screw extruder with a rotor housed in a cylindrical housing (screw), wherein the screw helix is designed as a grinding body with arranged on the screw spiral grinding elements;

Figure 13 is a section through screw rotor Figure 12;

FIG. 14 a dewatering press screw with grinding elements according to the invention;

Figure 15 is a plug screw with drainage capability;

FIG. 16 shows an extruder with different refining elements according to the invention;

Figure 17 is a plan view of the working surface (slats) of a refining element according to the invention;

FIG. 18 shows a section through a grinding element with a grinding element consisting only of hard metal lamellae, which is directly connected to the carrier plate by co-sintering, respectively. is embedded in this;

FIG. 19 shows a further embodiment of a grinding body with a (water) passage between the lamellae;

Figure 20 shows an extruder screw rotor with a helical flight;

Figure 21a shows an embodiment of an extruder element with a

(Water) passage in section; FIG. 21b shows a plan view of the extruder element:

Figure 21c is a plan view of a stamped carrier plate.

A known rotor 11 (FIGS. 1 to 3) used in a grinder has a mounting surface which is occupied by a plurality of chill cast plates 16. The chilled cast iron plates 16 are connected by means of screws or bolts 17 directly to the underlying rotor carrier disk 15. The chilled cast iron plates 16 are arranged in the radial direction (arrow 21) in three ring sectors. The arrangement in ring sectors is necessary because it is expensive to manufacture, the chilled cast iron plates 12,13,14 produce in larger dimensions and in the required accuracy.

The rotor 25 now differs from the known in that ring sectors 31, 33 and 37 are provided which at least partially consist of different materials (not only chilled cast metal). In addition, there is a sector with emergency running features, which the surpassed other sectors. In the exemplary embodiment shown with three ring sectors 31, 33, 37, for example, the middle ring sector 33 projects beyond the two other ring sectors 31 and 37 (FIGS. 4 and 5). As will be explained in more detail below, the ring sector 33 has "emergency running properties." Each sector 31, 33, 37 consists of a multiplicity of individual grinding elements 41. These grinding elements 41 are arranged on a carrier plate 51, which in turn is connected to the rotor Carrier disc 25. It is conceivable that the carrier plate is formed by the rotor carrier disc.

The rotor 25 is spaced from a stationary grinding disc (not shown in the figures), which may be of similar construction to the rotor carrier disc 25, i. can be occupied with the same grinding elements.

Figures 11 and 12 to 16 show various implementations of the invention. 11 shows, for example, that the grinding elements can be used in a conical grinder (left and right sides of FIG. 11 show conical rotors 25a arranged in a conical grinding housing 26.) The grinding angle 41 can be different both on the rotor 25a 12 shows an embodiment which has a conical rotor 25b with grinding elements 41 which have a working surface with a lamellar structure or a smooth working surface Passage be provided 42 (see Fig. 9).

The shape of the individual components and their mechanical connection is shown in Figures 6-10. As already mentioned above, each sector consists of a plurality of individual grinding elements 41. Each sector can be formed from a plurality of carrier plates, on each of which a plurality of grinding elements is arranged. These grinding elements 41 are generally smaller than the conventional chilled cast iron plates of known rotors. This means that a plurality of grinding elements 41 occur instead of a conventional chilled cast iron plate. The grinding elements 41 have a working surface 38, in which trenches 40 are incorporated, so that a lamellar structure is produced. On the working surface 38 opposite mounting side 36 mounting feet are provided. These can be dovetail-shaped (foot 44), polygonal (FIG. 10: foot 46) or rectangular with beads (FIG. 10) on average. Individual cylindrical feet 45 can be designed for precise fixing of the grinding elements 41 on the support plate 51 without undercuts.

The grinding elements 41 are arranged on a carrier plate 51. This can be a kind of intermediate plate with a sieve structure. The screen structure consists of a multiplicity of holes 50 (FIGS. 5 and 21) which serve to receive the fastening feet 45, 46, 47, 48 of the grinding elements 41. On the The grinding elements 41 opposite side of the support plate (bottom) hollow pins 53 are provided. The hollow pins 53 are received in 2ylindrischer recesses 65 on the underside of the support plate 51. The recesses 65 are preferably regularly distributed over the underside of the support plate 51 and can also overlap with the holes 50 for the Noppenfüsse (= Befestigungslemente) resp. agree with these.

The formation of the mounting feet 44 with an undercut, such as dovetails, has the advantage of secure attachment with it. The design polygonal or rectangular with beads (feet 46 or 48) allows a positive interference fit by local, plastic flow of the support plate, without the overall high residual stresses in the element. For fixed connection of the grinding elements 41 on the support plate 51, for example, an undercut having fastening (studded) feet with plastic 67 overmoulded, glued or potted by means of a solder (see below description of Figures 17 to 19). * ^■

The hollow pins 53 are used to attach the support plate 51, for example, on a known rotor disk 15. The hollow pins 53 may be distributed so that they match the pattern of mounting holes in conventional rotor disks. This has the advantage that rotors with conventional chilled cast metal plates can be equipped with new grinding elements according to the invention.

The embodiments according to FIGS. 4, 5, 9 are characterized in that drainage channels 42 are provided in the mowing elements 41. In the holes 50 hollow pins 54 may be added, so that a drainage through the hollow pins. 54 is possible. The drainage channels 42 extend through the mounting feet. This makes it possible that a liquid millbase can be dewatered during the grinding or digestion process. In the embodiment shown in FIG. 9, the connection between the grinding element 41 and the carrier plate 51 takes place by means of a solder 55. The solder 55 can be inserted or glued into grooves 66 of the hollow pin 54 (FIG. 9, bottom view of the hollow pin 54). By heating the solder 55 this can flow with a corresponding position of the grinding body in the gap between the dovetail-shaped mounting foot 44 and the cone-shaped end portion 43 of the hole 50. The bottom of the support plate 51 projecting end of the hollow pin 54 can take over the function of the hollow pin 53 and serve the attachment of existing of the refining element and the carrier plate grinding body on a rotor or stator.

According to the further advantageous embodiments shown in Figures 6 to 10, the mounting feet are formed so that the outer diameter of the inner diameter of the Holes substantially coincides. To fasten the grinding element 41 to the support plate 51, it is also possible to provide screws which are received in bores which are otherwise used as water passages. These are then cut as a thread and fall out as a water passage.

In the figures 12 to 16 circular sections of exemplary rotors are shown. The individual sectors shown correspond in size to the conventional grinding discs, which are integrally formed. In contrast to these, the sectors of the novel grinding discs are composed of a plurality of individual grinding elements 41.

FIG. 14 shows a dewatering press screw in which the screw 27 and housing wall 26 are occupied by grinding elements 41 according to the invention. The grinding elements 41 may be equipped with drainage channels 42.

FIG. 15 shows a plug screw, on whose housing wall 26 anti-rotation strips 69 are attached. These are designed so that they are occupied with grinding elements 41 with drainage channels 42. The drainage channels 42 communicate with a central drainage channel 56. In operation, liquid can be withdrawn through the drainage channel 56.

The extruder according to FIG. 16 is characterized in that grinding elements 41 with rectangular feet (only indicated in the figure) are arranged on the extruder screw. The grinding elements 41 can be made smooth without lamellae. For high pressures, the grinding elements are designed with overlaps in the material flow direction.

FIGS. 17 to 19 show a further embodiment of a grinding element 41 according to the invention, which has fins 58 made of hard metal. The fins 58 preferably have corrugations on the underside (not visible in the figure). These fins 58 are overmolded with a carrier plate 51. The fins 58 and the carrier plate 51 are then sintered together (co-sintered). The working surface of the fins 58 is optionally surface-compacted by duplex coating (layer 57). The reference numeral 60, the connection surface between the support plate 51 and the fins 58 is designated. The grinding element thus formed may optionally be fixed to a rotor or housing by means of a welding bead 61. This grinding body is characterized by a very compact design, in which grinding element and carrier plate are virtually one piece.

The variant of FIG. 19 shows a refining element, where the water passage 42 is arranged between the fins 58. The inlet can be formed by a eingelege hard metal plate with diffuser 62 his (slit-shaped diffuser).

Figures 20 and 21 show an exemplary embodiment of the high pressure part of a press screw. The invention will be explained in more detail below by way of example with reference to a high-speed refiner having three annular sectors 31, 33, 37 from inside to outside (FIG. 4, 5). The grinding media are here as Mahlplatten on an extremely fast-running disc rotor executed (first extreme case). The disc rotor may be cooled by injecting water.

The other extreme case is a slow-running press screw, the moist pulp dewaters (raw lignite 40% water content -, beet pulp, paper pulp and the like); as well a press-screw extruder for glass fiber or rock wool containing plastics. These examples will be explained below.

The sectors having different functions and working gaps of a high-speed grinding mill are characterized as follows:

The inner sector 31 is the place where the still coarse material (possibly with ceramic admixtures) must be slowly digested from the inlet ago. The working gap can therefore be higher than in the middle sector 33.

The rotational speed of the inner sector is smaller than the rotational speed of the middle and outer sectors. Steam bubbles and cavitation therefore do not play a role. In the inner sector 31, the coarse infeed and ceramic filler material must be digested. With regard to material design can therefore be used for the grinding elements chilled with high hardness, but still existing residual toughness (impact energy). Corrosion resistance may be considered in the alloy such that sufficient free chromium is available for the formation of solid oxide layers on the surface in the metal matrix. For fine grain carbide formation high temperature carbide formers such as V or Nb can be added. Therefore, the matrix will contain sufficient free chromium even with weight-based chromium contents of 24-28%, if the high carbon content is set by special carbides (like V or Nb etc.). The design of the inner sector 31 is preferably to be made so that the oxide removal by Tribox (abrasion of constantly newly formed, not sufficiently solid mixed oxides at the surface) is reduced. The micrograin bonding of the carbon through V, Nb or other metals is characterized by the matrix becoming firm and tough and sufficient metallic chromium remaining in the matrix so that the desired impact energy can be achieved. In the near-surface areas, so-called "shot peening" (directed shot peening) compressive stresses are generated. These prevent or delay microcracking. The lamellae of Mahlelementoberfläche are preferably tough and resistant to fatigue microcracks formed. The working edges are suitably solidified cold, so they are not susceptible to cracking. The inner sector may extend to a subsequent annular injection zone for 'makeup' water. The injection of make-up water is expedient, since the internal high frictional loss causes the aqueous pulp to partially evaporate. The systems are therefore under pressure. Larger amounts of water must be injected if the outer sectors are to contain water in the form of wet steam mixture. Against the inevitable drop impact (in the resulting wet steam), the lamellar elements must be made resistant. The wear processes are similar to those in pumps and wet steam turbines (cavitation, droplet impact) - enhanced by frictional oxidation (Tribox) due to the introduced ceramic fillers (similar to mud dumps).

The middle sector 33 of the rotor disk is preferably embossed with high temperature resistance. The high-temperature resistance can be achieved by the incorporation of tough-bonded metal carbides. High temperature carbides endure the incipient vapor bubble and drop formation. The incorporation of high temperature carbides, e.g. WC, TiC, SiC-SiN, possibly also borides or similar hard phase formers, in the finest grain size make this sector corrosion and heat resistant, so that a partial rubbing on this sector does not cause catastrophic damage.

For example, powder-pressed grinding elements 41 made of Ti-stabilized tungsten carbide in cobalt (used in rock drill bits as 'mining bits' usual) form individual sector parts with emergency running properties. These sector parts having a melting temperature of preferably. > 2500 ⁰ C do not crack or melt during the development of frictional heat. Accordingly, this is. Sector used for the defined distance.

The considerable lateral forces on the grinding elements can be absorbed by appropriate fastening elements, eg knobbed feet. These dimpled feet 45, 46, 48 penetrate the holes, which are preferably tapered in the carrier plate 51 from behind. The attachment of the studded feet can be done by a distortion-free low-temperature soldering. Alternatively, an encapsulation of the knobbed feet is conceivable. Such grinding elements of complicated geometry can be manufactured inexpensively and precisely by PIM (Powder Injection Molding). The various grinding elements that form a sector can be produced fully automatically in large series on existing plastic injection molding machines. Only minor (wear-protective) conversions are necessary to prepare them for the production of the inventive sector parts. The middle sector 33 is characterized in that it operates with the lowest working gap and thus has surface contact as the first sector when the rotor disks are not completely avoidable. Due to the hard body properties, this rubbing can be tolerated for process irregularities for a short time, since the friction generated quickly generated temperature of> 2000 ⁰ C due to the high melting point of the carbide-containing material (WC, etc.) of> 2800 ⁰ C safely (emergency running properties). As a result, the entry of metal particles by wear, in particular the entry of easily oxidizable iron in the fine paper material is avoided. The properties of lamella bodies made of pressed carbon fibers - as provided in the outer ring - make them appear suitable for the middle ring, if the material to be processed is not too high demands.

The outer sector 37 of the rotor disk with the highest-loaded grinding elements can be made of much cheaper ceramic lamellar bodies. Shaping is also possible with PIM (Si-Al-Zr oxide). The outer sector 37 may also be made of pressed and sintered Keramik¬ or carbon fibers. Especially for carbon fibers can be applied in addition to the working edges DLC (diamond like carbon) directed (prior art). The grinding elements 41 of the outer, annular sector 37 can also be glued and / or screwed directly onto the rotor. Thanks to the light materials used, much higher speeds can be achieved with the same forces than with conventional refiner plates made of a carbide casting.

An advantage of the modular grinding plates is that experience shows that optimum edge geometries can be pressed at no extra cost. Because it is possible to determine an optimal working edge geometry for the shape of the ceramic parts and implement them directly by injection molding. As a result, optimal operating conditions can be achieved for more than 90% of the operating time. The service life of the refining plates according to the invention far exceeds that of chilled refractory plates by far.

The grinding elements with knobbed feet can be inserted into drill holes in the carrier plate and, for example, molded or glued from behind in precise position with high-strength plastic. This can already happen at temperatures below 150 ⁰ C. Stripping of the outer sector can be excluded by the middle sector.

The outer sector 37 is characterized in that it contains inexpensively interchangeable segments or sector parts. It can also be used here elements of pressed carbon fibers, DLC possibly coated (diamond like carbon). The low specific weight allows the direct attachment of the sector parts on the rotor plate and thus even higher speeds at lower centrifugal forces. If necessary, the elements can be mounted directly on the drilled rotor disk. The outer sector may also consist of carrier plate segments which are connected to the hub via a grid of short pins. The outer rotor disc (carrier plate 51) can be made as a screen and easily changed.

Due to the safe spacing of the rotor disks in the middle sector, the outer sector can be formed from ceramic material grinding elements which best endure the high-speed droplet impact that is unavoidable in the outer sector as well as the fretting wear due to the fillers. The ceramic grinding elements 41 can also be inexpensively manufactured precisely in the PIM process. As the material, a more favorable ceramic compound such as e.g. Si-Al-Zr oxide, to be used in the middle sector. The attachment is done as in the other sector parts preferably by Noppenfuße.

Like the other sectors, the outer sector 37 may consist of cost-exchangeable refining elements 41: the outer sector of a high-speed refiner accounts for more than 70% of the grinding capacity. Due to the optimized material properties and geometry of the outer sector parts, a high product quality can be ensured for more than 90% of the operating time. For particularly high speeds and centrifugal forces also grinding elements made of pressed carbon fibers, possibly with "diamond-like-carbon" (DLC Due to the low specific weight of the sector parts used, the centrifugal forces are lower, and the speed and thus the performance can be increased.The light outer grinding elements can also be applied directly to the rotor disk, which can therefore be slim and light be designed, for example, manufactured as a screen disc or sieve segments.

The advantages of the grinding media according to the invention. Grinding elements are: Flexible construction of the rotor system in a high-speed grinder (High Speed Refiner) and suitability for a wide variety of starting materials and end products. Mills with the inventive grinding elements and grinding media allow an additional power of up to 20-40% with> 20% power savings. The product quality is also higher and more uniform than with conventional grinding wheels. Retrofitting of existing mills is possible in many cases and allows a broad service business.

Use of grinding elements in press screws for raw lignite, beet pulp or

Fibers:

The grinding media can be mounted here both on the working edges of the screw and on the wiper strips of the housing (FIG. 14). In the grinding media of the conical, possibly cylindrical housing are holes under the grinding elements 42 (Fig. 9), these serve for dewatering, since the Raw material contains 40-60% water and is to be dewatered for the subsequent production steps. During cooking or drying, evaporation energy is thus saved. The largely dehydrated material is then squeezed out through the mouthpiece and processed compactly.

Use of the grinding elements in press screws for fine paper stock: (dewatering screw for fine paper stock)

The inventive grinding elements are here mounted on the working edges of the screw and on the entire circumference of the housing. The assembly of the grinding elements, which serve here as working edges for the screws, can be carried out on a stamped carrier plate, which has lateral outlets for press water from the high-pressure region near the outer edge. Extended lugs are punched out between the outlets, which can be bent over and used for fastening by short, detachable weld beads (see Figures 20 and 21) The optimum lamellar shape of the surface 38 for the respective substance can significantly favor the material flow and in the decisive area between Screw working edge and housing grooves ensure optimum pressure conditions for drainage. The work gaps remain stable due to the carbide grinding media for a long service life. The standstill and conversion costs are thereby reduced. The usual designs have welded Schπeckenkanten and a housing screen made of stainless steel with grooves and drainage holes, which round off quickly at the edges. This leads to blockages and stoppages.

Pressing screws (extruder for plastic (filled with glass, stone or carbon fiber), but also for brickwork or ore treatment sludge and the like) ^■ >

The inventive grinding elements are used here to protect both the working edge of the extruder screw and the inner wall of the housing. The arbitrarily malleable grinding elements are here for some applications without drainage holes such as 42 executed. For high pressures, the grinding elements are designed with overlaps in the material flow direction, 49. Thus, the tolerances are to be kept within a range that allows production by the powder injection process (PIM) without post-processing. Again, a directed lamellar structure of the surface can bring significant process advantages (service life and material handling). Legend:

11 rotor (a refiner)

12,13,14 sectors of traditional grinding discs

15 rotor carrier disc

16 chilled cast iron plates

17 screws or bolts 19 supporting body

21 rotor refiner

25 rotor carrier disc

26 opposite rotor disk or worm

27 (Press) auger 8 Stopfschnecke 9 Extruder 1 inner sector of grinding media

33 middle sector of the grinding media 6 attachment side of the grinding element 7 outer sector of the grinding elements 8 'working surface of the grinding elements 0 trenches in the grinding elements (lamella) 1 lamella element 2 water passage in the grinding element 3 conical bore or pressed conical punching in the carrier plate, 4 dumbbell-shaped foot (with undercut) for overmolding or gluing. 5 cylindrical foot for precise fixing 6 polygonal foot, for limiting transverse stress peaks 7 undercut, for fixing with solder (with water passage with cavern pin 54) 8 rectangular passing fixation foot with 'beads' - like 46 9 edge element with rectangular web and beading 0 holes in the carrier plate 1 carrier plate Flat lamellar elements with slotted water passage and beaded feet Cylindrical hollow pins for fixing a carrier plate in the rotor carrier disk 25 Cavern pin for supplying solder (without water passage blockage), solder glued into strips in 54-cavity cavities. Water diffusers (duplex) coating Fins made of tungsten carbide Chromium steel, preferably ferritic or duplex (ferritic austenitic) co-sintered (carbide with beads in 59) Dissolvable weld joint Water passage as diffuser Holes punched, with cold pressed mold (like 43) Grooving of hollow pin 54 cylindrical recesses for pins 53 Plastic (encapsulation of dimpled feet) Antirotation strips

Claims

1. grinding element with a smooth or lamellar structure provided with the working surface (38) characterized in that at the working surface (38) opposite fastening side (36) for fixing the grinding element in corresponding holes of a supporting body (19) at least two fastening elements (44,45) are provided, which preferably have undercuts (44), beads (48) and / or corners.

2. Grinding element according to claim 1, characterized in that in the elements through holes or passages (42) are provided, which holes or passages (42) can be used for injection or dewatering.

3. refining element according to claim 1 or 2, characterized in that the holes are formed as slots (62) with diffuser-like outlet.

4. grinding element according to one of claims 1 to 3, characterized in that the grinding elements in the powder molding or preferably in the powder injection molding process (PIM: powder injection molding) are prepared.

5. grinding element according to one of claims 1 to 4, characterized in that the grinding elements are surface-compacted, for example by duplex coating: diffused ion nitriding + IBAD, ion beam assisted deposit of WC-Co, TiN, DLC or the like.

6. grinding element according to one of claims 1 to 5, characterized in that a first type of grinding element (41) is made of high temperature resistant materials. "

7. Grinding element according to claim 6, characterized in that the first type of grinding element (41) made of hard metal with high temperature carbides, high temperature (mixed carbides, nitrides or borides or mixtures thereof with cobalt matrix.

8. Grinding element according to claim 6 or 7, characterized in that the first type of grinding element (41) made of hard metal with WC, TiC, SiC-SiN, possibly also borides or the like Hard phase former with eutectic matrix type Ni / Co-Cr-V-Nb-B-Si-C is produced.

9. Grinding element according to one of claims 1 to 5, characterized in that a second type of grinding element (41), made of ceramic materials, is provided.

10. Grinding element according to claim 9, characterized in that the second type of refining element (41) is made of Si-Al-Zr oxide.

11. Grinding element according to claim 9, characterized in that the second type of grinding element (41) is made of pressed carbon fibers, optionally with DLC coating.

12. Mahlkörper with grinding elements according to one of claims 1 to 11, dadarch in that a support body (19) with drilling or punching holes (50) is provided, and that the grinding elements with the fastening elements (44,45) in the drilling or Punching holes (50) are positively received.

13. Grinding body according to claim 12, characterized in that the fastening elements (44,45) with beads (48) and / or corners are made by cold pressing and in the holes (50) of the support body (19) are inserted low in own stress.

14. grinding body according to claim 12 or 13, characterized in that in the drilling or punching holes (50) arranged fastening elements (44,45) molded with plastic, glued or soldered.

15. Grinding body according to one of claims 12 to 14, characterized in that the first type of grinding element (41) in the support body (19) by co-sintering of grinding element and carrier body (19) is inserted, preferably by two-step pressing of Milling elements and supporting body (19) in the same mold (powder press or PIM process).

16. Grinding body according to one of claims 12 to 15, characterized in that the first type of grinding element (41) with a compacted surface on a support body (19) such Geometry is inserted, that a welding / -heften on work surfaces of apparatus is possible without extending the heat affected zone in the grinding element.

17. Grinding body according to one of claims 12 to 16, characterized in that on the support body (19) grinding elements (41) of the first and second types are provided.

18. Grinding body according to one of claims 12 to 17, characterized in that a plurality of grinding elements (41) of the same type are each adjacent to each other to form sectors with certain grinding properties or form working edges with the same properties.

19. Grinding body according to claim 18, characterized in that the grinding medium in the material flow direction has at least two sectors with grinding elements (41) of the first or the second type occupied sectors.

20. ^• grinding media according to claim 19, characterized in that the media in

Material flow direction three with each grinding elements (41) of the same type equipped sectors (31, 33,37) has, which may have the following combinations of materials: chilled, hard metal, ceramic or chilled, hard metal, hard metal or ceramic, hard metal, hard metal or ceramic, hard metal, carbon fiber part , or hard metal, hard metal, carbon fiber part or chilled cast iron, hard metal, carbon fiber part, etc.

21. Grinding body according to one of claims 12 to 20, characterized in that the working surface (38) of the sector (33) with the grinding elements of the first type, the surface of the sector (31,37) projects beyond with grinding elements (41) of the second type.

22. Grinding body according to one of claims 12 to 21, characterized in that the grinding body has at least three sectors occupied with grinding elements (31,33,37), wherein a at least one sector is occupied by grinding elements of the first type.

A grinding media according to claim 22, characterized in that the sector with grinding elements of the first type is the middle sector (33).

24. Grinding body according to one of claims 12 to 23, characterized in that the grinding elements are lamellar bodies with surface structuring (40,58).

25. Grinding body according to one of claims 12 to 24, characterized in that the supporting body (19) made of martensäturing or outsourced duplex steels, i. ferritic chrome steels with low spec. Expansion coefficients, is made.

26. Grinding body according to one of claims 12 to 25, characterized in that the supporting body (19) is designed as a grinding disc with at least 3 in the material flow direction annular sectors (31,33,37), wherein preferably the central sector (33) of Sector with refining elements of the first type and has emergency running properties and the other two sectors (31,37) surpasses a certain amount.

27. Grinding body according to one of claims 12 to 26, characterized in that the supporting body (19) is reduced in thickness in the outer annular region and optionally designed as a sieve-shaped support plate with holes (50) for knobbed feet and / or screw holes.

28. Grinding body according to one of claims 12 to 27, characterized in that the supporting body (19) is designed as a cone or roller.

29. Mill, in particular high-speed refiner for paper stock, with grinding bodies designed as grinding disks according to one of claims 12 to 29.

30. Mill according to claim 29, characterized in that in the radial direction at least two sectors with refining elements (41) of the first or second type are provided and at least one annular sector (31,33,37) is made of high temperature resistant materials, ie grinding elements (41) of the first type and having "runflat" properties.

31. Mill according to claim 29 or 30, characterized in that the gap width between the opposing grinding elements (41) with emergency running properties is smaller than the gap width between the other grinding elements.

32. Press-screw with trained as working edges grinding bodies according to one of claims 12 to 29.

33. The screw press according to claim 32, characterized in that the grinding bodies are screwed, soldered or welded to the rotor of the press screw.

34. Pressing screw according to claim 32 or 33, characterized in that the housing of the press screw longitudinal strips (69) which are occupied by grinding elements (41).

35. The screw press according to one of claims 32 to 34, characterized in that the grinding elements (41) have at least one drainage hole (42).

36. Compressing screw according to one of claims 32 to 35, characterized in that the housing (26) with grinding elements (41) is designed with a drainage opening (42), so that the housing may be suitable for drainage all around.

37. Compression screw according to one of claims 32 to 36, characterized in that supporting body (19) for the grinding elements (41) are provided, which support body (19) are provided with tabs, with short, detachable welds (55) on the rotor of Press screw are attached.

38. The screw press according to one of claims 32 to 37 for use as extruder for plastics, plastics filled with powders and fibers (PIM), ceramic / organic sludges (brown coal to food) or pure ceramic sludges (for example brickwork presses).

39. Mahlkörpεr with a support body (19) and at least two on the support body (19) provided grinding elements (41), which in a certain direction, which is defined by the transport direction for a material to be ground, subsequently as the material flow direction designated, are arranged one behind the other, characterized in that a first grinding element (41) is made of materials that ensure "emergency running properties", and that the working surface (38) of this first grinding element, the surfaces (38) of the other grinding element (41 ) surmounted by a certain distance.

40. Grinding body according to claim 1, characterized in that the first grinding element (41) is made of high temperature resistant materials.

41. Grinding body according to claim 1 or 2, characterized in that the first grinding element (41) made of hard metal with high-temperature carbides, high-temperature (mixed) carbides, - nitrides or borides or mixtures thereof.

42. Grinding body according to one of claims 1 to 3, characterized in that the first grinding element (41) made of hard metal with WC, TiC, SiC-SiN, possibly also borides or similar hard phase is produced.

43. Grinding body according to one of claims 1 to 3, characterized in that the first grinding element (41) is made of pressed carbon fibers.

44. Grinding body according to one of claims 1 to 5, characterized in that at least one further second grinding element (41) made of ceramic materials such as Si-Al-Zr oxide is provided.

45. Grinding body according to one of claims 1 to 6, characterized in that the second grinding element (41) is made of pressed carbon fibers, optionally with DLC coating.

46. Grinding body according to one of claims 1 to 10, characterized in that a plurality of the same, mutually adjacent grinding elements are each combined into sectors (31,33,37) with certain grinding characteristics and the grinding body a plurality of sectors (31,33 , 37) each with similar grinding elements, ie of the first or second type.

47. Grinding body according to one of claims 1 to 9, characterized in that the grinding body has a supporting body (19), on which the first and second grinding elements are arranged.

48. Grinding body according to claim 1 1, characterized in that the individual grinding elements (41) on the back (36) fastening members (44,45) which are fixedly connected or connected to the support body (19).

49. Grinding body according to claim 11 or 12, characterized in that the fastening elements are feet with undercuts (44) which are received in holes provided therefor (50) of the support body, preferably in round holes with a top conical bore (43).

50. Grinder according to claim 13, characterized in that in the holes (50) received dovetailed feet (41) are encapsulated in plastic.

51. Grinding body according to one of claims 11 to 14, characterized in that the grinding elements (41) are lamellar bodies with surface structuring (40,58).

52. Grinder according to one of claims 11 to 15, characterized in that the grinding elements (41) in the powder injection molding process (PIM: powder injection molding) or by hot isostatic pressing (HIP: hot isostatic pressing) are made.

53. Grinding body according to one of claims 1 to 16, characterized in that it has at least two sectors in the material flow direction, which are made of different materials.

54. Grinding body according to one of claims 1 to 17, characterized in that the grinding elements are designed as sieve plate segments with martensizing or outsourced duplex steels.

55. Grinding body according to one of claims 1 to 18, characterized in that the supporting body (19) as a grinding disc (25) is formed with radially in the radial direction sectors (31,33,37).

56. Grinding body according to claim 19, characterized in that the grinding disc in the radial direction at least 3 annular sectors (31,33,37), wherein preferably the middle sector of the first sector is with runflat properties and the other two sectors surmounted by a certain amount ,

57. Grinding body according to claim 8, characterized in that the first grinding element (41) is the middle sector and the surface (38) of the first grinding element (41) is offset from the surfaces (38) of the other two (second) grinding elements.

58. grinding body according to claim 19, characterized in that the supporting body (19) is reduced in thickness in the outer annular region and optionally designed as a sieve-shaped support plate with holes for knobbed feet and / or screw holes.

59. Grinding body according to one of claims 1 to 18, characterized in that the supporting body (19) is designed as a cone or roller.