DE9319599U1 - Shredding machine with rotor - Google Patents

Description

Dr.-lng. Reimar König ·.".: pipMn^.KtafljS^

Wilhelm-Tell-Str. 14 4O219 Düsseldorf!.Sel.lDSI 1,-5iai«32B ..

22.Dec.1993

40 288 B

LINDEMANN Maschinenfabrik G.m.b.H., Erkrather Str. 401,

40231 Dusseldorf

"Shredding machine with rotor"
The invention relates to shredding machines with rotors.

Such crushing machines are known in various designs and for different feed materials. For example, there are designs in which the support bodies for the crushing tools consist of a spider rotor or a one-piece rotor body. A particularly advantageous design is the hammer crusher according to German patent specification 26 05 751, whose rotor consists of several disks fixed to a shaft and of hammers distributed between them, which are mounted so that they can rotate.

The crushing machines mentioned are used to crush metallic or non-metallic material or a mixture of these two types of material and almost always consist of a fixed housing in which the rotor is rotatably mounted. On the inside of the housing there is usually a so-called anvil, preferably at the inlet of the housing, which in the case of the hammer crusher according to the patent mentioned interacts with the movable impact tools or hammers mounted on the rotor. For this purpose the rotor, which is usually coupled to a fast rotating drive, is equipped with a large number of axes parallel to the rotor shaft, but eccentrically offset from it, on which

the hammers or rotor tools are mounted so they can rotate freely. The crushing takes place through the interaction of the rotor hammers with both the fixed anvil at the material inlet and with the inner wall of the housing, which functions as a counter tool, against which the material is thrown and, at least in a partial area of the rotor circumference, is crushed or torn between this and the crushing tools.

The rotor hammers are arranged in some suitable manner around the circumference of the rotor at a distance from one another. In order to create this distance, the rotor body consists of a large number of disks, all of which are connected to the rotor shaft in a rotationally fixed manner.

Particularly when the material to be shredded is made entirely or partially of metal, the outer surfaces of the disks, between which the rotary hammers are pivotably mounted, suffer considerable wear and tear due to abrasion and impact of the pieces of material. After a relatively short period of operation, so much metal is torn off or ground off the circumference of the disks that the disks become unusable and have to be replaced or welded on at great expense.

The proposal according to the patent mentioned counteracts this disadvantage by using protective shields or so-called protective caps made of particularly wear-resistant material, which essentially consist of a cover part in the form of a circular ring segment and a bearing hub provided on the inside of the cover part and are fastened to axle rods with these, and cover the peripheral surfaces of the adjacent disks with their cover parts.

• *

·

Although this type of hammer crusher has already proven itself to be extremely effective in practice for almost two decades, it must be remembered that both these well-known protective caps and the crushing tools, i.e. the hammers in the case of this hammer crusher rotor, are cast, so that these parts are not only relatively expensive to manufacture, but also require relatively large casting tolerances that must be taken into account when constructing the machine and installing the aforementioned parts.

Furthermore, the wear on hammers and protective shields or protective caps is different, since the hammers as active tools are subject to greater stress than the inactive protective shields or protective caps, so that different service lives apply to both components subject to wear, which lead to different intervals for their replacement and/or reconditioning, resulting in correspondingly irregular and therefore time-consuming downtimes for the shredding machine.

These difficulties apply to an even greater extent to the other types mentioned at the beginning, whose protective shield or protective cap systems, if they have one at all, are nowhere near as simple as those in the patent mentioned. What all shredding machines of this type have in common is that the tools and, where applicable, the wear-protecting parts are cast parts.

Finally, there are known solutions, including those according to German patent specification 31 23 857 and German utility model specification 92 06 489, which aim for high wear resistance but are one-sidedly focused on active

Wear parts or tools remain limited and are also costly.

The invention is based on the object of optimizing set-up times and reducing the costs of manufacturing individual parts. This object is achieved in a surprisingly simple manner by the features and measures specified in the main claim.

When we speak here of "active" wearing parts on the one hand and "inactive" wearing parts on the other, these terms take into account that the crushing tools, for example the hammers, are subject to a different type of wear (active wear) due to their active crushing work than the covers used to protect other machine parts from wear, such as the protective shields, which do not actively participate in the crushing process, but are worn by the swirling feed material, as mentioned at the beginning, through abrasion and impacting pieces of material (secondary wear of the inactive components).

The teaching according to the invention not only leads to an increase in service life by achieving fewer different change phases of the active and inactive wear parts, but also opens up a wide range of design options for an optimal wear part system. This is particularly advantageous for use in shredding machines whose rotor consists of disks, preferably essentially circular disks.

The coordinated wear behavior proposed within the scope of the invention can be achieved in a variety of ways, with a particularly preferred embodiment consisting in at least one of the two

► ·

Wear part types are joined in a composite construction. This makes it possible to select the shape and material for the individual parts of the composite so that the composite can be adapted in its wear behavior to that of the other components, whereby it is of course also within the scope of the invention that one type of wear part, for example the hammer, is still made of cast iron, while the other type of wear part, for example the protective shields or cover caps, consists of a composite of different steel sheets, or vice versa.

The composite construction has the surprising advantage that significantly lower tolerances are required than with cast parts, so that fitting problems are minimized while at the same time the construction is more compact. With the laser burning technique, the parts that form the composite can be manufactured efficiently and with a precise fit, for example from sheet steel.

As an alternative to the composite structure, at least one of the two types of wear parts can consist of zones with different material properties, such as quality, hardness, toughness and/or thickness. This can be achieved, for example, through targeted heat treatment. The cover surfaces or the covering parts of the inactive wear parts (protective caps) can thus be given a greater hardness that is more resistant to wear than their webs and hubs.

In an embodiment of the invention, it is proposed that the active and/or inactive wearing parts are joined in a detachable and/or non-detachable manner, so that on the one hand screws or rivets and on the other hand soldering, welding, gluing, etc., or combinations thereof, can be used for the connection.

A particularly advantageous composite is the sandwich construction, in which, in a further embodiment of the invention, at least parts of the wearing parts are made, for example the hammer as a whole and of the protective cap only its cover part or cover surface.

If the hammer structure is such that two relatively hard, wear-resistant layers or layers enclose at least one softer one between them, i.e. are attached on both sides to the side surfaces of the softer core layer, then a self-sharpening sandwich construction for the hammers is advantageously achieved, since the softer core layer on the free end faces then wears faster than the harder side cover layers, so that the end of the hammer in the area of the core takes on a retracted shape, whereby the cover layers protruding in comparison lead to better crushing efficiency and greater stability.

This cross-sectional shape, which is recessed or retracted at the impact or crushing edges of the hammer in its core area, can also be provided in unused hammers due to the sandwich construction according to the invention, by choosing the softer core layer to be smaller in size than the harder cover layers at these points.

The softer, preferably tough material layers or areas have a particularly advantageous effect in the area of the bearing eyes, hammers and protective caps, which are equipped with harder bushings, for example, but also have considerable advantages as core layers for the hammers and in the case of the multi-layer composite construction of the cover parts of the protective caps, for example

_ 7 *■■

as a base or intermediate layer which considerably reduces the risk of breakage of the wearing parts.

The inventive construction of the wear parts from layers, zones, areas and/or layers with different material properties enables not only the mutual adaptation of the wear behavior and the optimal adjustment to the composition of the feed material, but also new ways of spatially assigning the two types of wear parts to each other, in that layers or areas can now be joined together in such a way that, due to their different properties as a composite component, they can then also fulfill several tasks at the same time. For example, an inactive wear part, in this case a protective cap, on the side walls can be designed or constructed in such a way that, for example, bearings for the hammers can be created or accommodated there, which means that an axle rod attachment for the hammers is no longer necessary, which in individual cases can make it easier to change hammers.

In the case of hammers, the softer intermediate or core layer does not need to be covered with harder cover layers over its entire two main lateral surfaces, rather the latter can have openings extending to the core layer, in particular only in the lateral edge area, preferably in a shape adapted to the outer contour of the hammer, including the recess in the cover layer. This saves material; the production of these contoured cover layers with openings is easily possible using laser cutting and/or contour burning. If in this case the cover layers are preferably welded onto the core layer, then the hardness profile in the edge area of the core layer can also be influenced in an optimal way for the wear behavior of the hammer.

With regard to the design of the surface and/or body shapes for the wearing parts, in particular hammers, it is within the meaning of the invention that these can be adapted to the different wear zones and behavior.

The invention provides a further advantage for the protective caps, in particular their cover parts or cover surfaces, since these can now each consist of angled partial surfaces, i.e. it is then only necessary to bend flat plates or sheets in order to more or less approach the rotor radius, which is more cost-effective and simpler than correspondingly curved cover parts, but in particular offers an enormous price advantage in production compared to the previously known cast protective caps. In principle, the angled cover surface can also consist of flat partial surfaces that are joined together accordingly. With this measure, the curved shape of the cover surface can be replaced in a simple and diverse way by a polygonal welded construction.

The advantages of the composite construction according to the invention not only simplify the manufacture of the wearing parts, but also open up different shapes that are easy to manufacture for the cover parts of the protective caps, which results in design options for the rotor protective casing that are particularly well adapted to the use of the shredding machine and the mutual influence of the parts moving relative to one another. For example, the cover parts or cover surfaces can be offset or notched in their angled peripheral surface, i.e. designed in an L-shape, so that the meandering course of the contact lines of the cover parts on the one hand avoids a circumferential contact line.

which could cause particular wear in this area over time, and on the other hand this also provides an even greater possibility of variation in the hammer pattern while simultaneously reducing contact slots or separating joints between adjacent protective caps. This variable shape of the protective caps also enables the free spaces required for the hammer to swing through to be optimally designed.

If protective caps are provided with offset or notched design in their cover surface, it may be advisable to provide two axially aligned bearing eyes in the wider protective cap area so that the brackets extend between at least three adjacent rotor disks. If the cover part spans two hammer axes circumferentially, it is advisable to arrange at least one further bracket radially or circumferentially offset.

Further details of the invention, which are explained in more detail below using the embodiments shown in the drawings, can be found in the remaining claims and the following description. In the drawings:

Fig. 1 is a longitudinal section through a rotor of a shredding machine along line II in Fig. 3 at positions "c" and "e" with the arrangement of the wearing parts according to Fig. 4;

Fig. 2 is a longitudinal section through a rotor along line II in Fig. 3 at positions "c" and "e" with the arrangement of the wearing parts according to Fig. 5;

Fig. 3 a cross section through a rotor along line II-II in Fig. 1 or Fig. 2 with the fastening

Positions "a" to "f" for the wearing parts, whereby at positions "a" and "b" an inactive wearing part according to Fig. 15 or Fig. 17 and corresponding to Fig. 6 is shown;

Fig. 4 is a schematically illustrated development of a rotor shell to illustrate the arrangement of the wearing parts according to Fig. 1 in the positions "a" to "f" according to Fig. 3, wherein the active wearing parts are shown folded by 90° into the plane of the drawing for better differentiation;

Fig. 5 is a schematically illustrated development of a rotor shell to illustrate the arrangement of the wearing parts according to Fig. 2 in the positions "a" to "f" according to Fig. 3 and representation of the inactive wearing parts according to Fig. 16;

Fig. 6 is a schematically illustrated development of a rotor shell analogous to Fig. 4 and Fig. 5 with inactive wear parts according to Fig. 13 to 15 to illustrate a special assignment of the wear parts with regard to a coordinated wear behavior;

Fig. 7 is a perspective, simplified representation of a rotor of a crushing machine with a schematic arrangement of the active wear parts in centrifugal force function and the inactive wear parts corresponding to the cover surfaces according to Fig. 15 or Fig. 17;

Fig. 8 an active wearing part in a composite construction, in particular a sandwich construction;

Fig. 9 an active wearing part in a composite construction, in particular a sandwich construction, with detachable and non-detachable joining types and layers of different hardness;

Fig. 10 an active wearing part with zones of different hardness and representation of the wear condition;

Fig. 11 an active wearing part in a composite construction and in particular a self-sharpening sandwich construction;

Fig. 12 Representations of the wear state of a conventional (Fig. 12a) and an active wear part according to the invention (Fig. 12b);

Fig. 13 an inactive wearing part made of a composite of cover surface and holder with different hard zones, layers or positions of the cover surface;

Fig. 14 an inactive wearing part with a cover surface consisting of angled partial surfaces;

Fig. 15 an inactive wearing part with an offset or notched cover surface and two radially or circumferentially offset holders;

Fig. 16 an inactive wear part with two axially aligned holders; and

Fig. 17 an inactive wear part with three holders, two of which are axially aligned and the third is radially or circumferentially offset.

- 12 -

The following embodiments are explained using the example of a crushing machine designed as a hammer crusher. According to Fig. 1 and 2, a rotor 2 with a shaft 3 is rotatably mounted in a housing 1 indicated by dot-dash lines, not shown in detail. Several disks 4 are held in a rotationally fixed manner on the shaft 3, e.g. by a feather key 5 (Fig. 3, Fig. 7).

However, the invention is not limited to a rotor 2 consisting of disks, but is also applicable to other supporting bodies of comminution machines, for example a cross-arm rotor or a one-piece rotor body.

The shaft 3 can be set in rotation by a drive not shown.

The disks 4 consist of flanges 4.1 and hubs 4.2 and have holes 4.3 that are on the same pitch circle. The disks 4 lie close to one another with their hubs 4.2 on the shaft 3 and are designed as end disks 4.4 with covers 4.5 at the rotor ends.

Together with the hubs 4.2 and the flanges 4.1, the disks 4 on the shaft 3 form a multi-part rotor or support body of the rotor 2 for the hammer crusher (Fig. 1 and 2).

Axle rods 6 are provided parallel to the shaft 3 and radially against it and offset from one another, which pass through the holes 4.3 in the disks 4 corresponding to the positions "a" to "f" (Fig. 3). The axle rods serve as fastenings for active wear parts 7, so-called hammers, and for inactive wear parts 8, so-called protective caps.

- 13 -

The active wear parts 7 are rotatable on the axle rods 6, i.e. freely rotatable, eccentrically mounted and in the centrifugal position (Fig. 3) in cooperation with one or more counter tools (not shown) of the housing 1, they crush a feed material not specified here.

The inactive wearing parts 8 form with their cover surfaces 8.1 a substantially cylindrical shell that protects the disks 4 from wear.

In Fig. 4, 5 and 6, for example, arrangements of the wearing parts 7, 8 are shown schematically as a developed view. The Roman numerals indicate the center lines of the spaces between the flanges 4.1 of the disks 4 and the letters "a" to "f" indicate the center lines of the axle rods 6. The fastenings or bearing points of the rotating active wearing parts 7 are in the area of the intersection points f-III, f-VII, fx, eI etc. and the fastening points or holders of the inactive wearing parts 8 are in the intersection points fI, f-II, f-IV etc. (Fig. 4), or fI/II, f-IV/V/VI, f-VIII/IX etc. (Fig. 5), or fI, f-II, f/e-IV etc. (Fig. 6). From this, in conjunction with Fig. 1, 2 and 3, it can be seen that the active wear parts 7 can swing through (centrifugal force function) in the free spaces 9 (Fig. 1, 2 and 7) which are delimited by the inactive wear parts ₈ in the working position, ie when the rotor is rotating. This state of the rotor 2 is shown in simplified form in Fig. 7. The free spaces 9 formed by the arrangement and design of the inactive wear parts 8 and the active wear parts 7 which indicate the operating state and protrude outwards due to the centrifugal force effect can be seen.

The different arrangements of active and inactive wear parts 7, 8 according to Fig. 4 to 6 in connection

with Fig. 7 are intended to illustrate that the functional unit rotor 2 with the active wear parts 7 and the inactive wear parts 8 is subject to active and inactive wear during the crushing process in the sense of the invention. As a rule, the wear of the active wear parts 7 is inevitably a multiple of the wear of the inactive wear parts 8. In the sense of the purpose of the invention, this different wear is to be designed for coordinated, preferably consistent intervals.

The further explanations show that the active and inactive wear parts 7, 8, which are adapted to the wear during the comminution process in their structure, shape, material composition and/or mutual assignment according to the invention, lead to a coordinated, advantageous wear behavior.

In Fig. 8, a hammer is shown as an active wear part 7 in a composite, in particular sandwich, construction in side view and in section. In the sense of the invention, joining in a composite construction includes detachable and/or non-detachable joining means or types, such as screws, bolts, dowel pins, rivets, welding, soldering, shrinking, gluing or similar, either individually or in combination. This hammer 7 consists of a core layer 7.1 and cover layers 7.2 on both sides as well as a bore 7.3 for the rotatable, eccentric bearing on the axle rods 6 (Fig. 1, 2, 3 and 7). The cover layers 7.2 are perforated in the shape of the outer contour of the hammer 7, so that the core layer 7.1 is exposed in the area of the bore 7.3 and the inner edges of the cover layers 7.2. The cover layers 7.2 have a greater hardness than the tough or softer core layer 7.1. This makes it advantageous to store the bearing area of the

—15—

Hammers 7 tough and the actual active wear area can be made hard and wear-resistant.

Another version of a hammer 7 with hard cover layers 7.2 and soft core layer 7.1 can be seen in Fig. 9, which shows in the corresponding longitudinal sections for fixing the hard cover layers 7.2 to the softer core layer 7.1, detachable and non-detachable connections 7.4 by means of bolts, dowel pins, rivets and hole welding. It is possible - as mentioned above - that the individual layers 7.1, 7.2 can also be joined by screwing, soldering or gluing, or with the appropriate design, by shrinking.

Another version of a hammer 7 according to Fig. 10 consists of a part which is treated in such a way (heat treatment, tempering) that hard zones 7.5 are created compared to the untreated structure and a soft zone 7.6. The section 10a shows the hammer in its new state and section 10b shows it in its used state with the resulting self-sharpening profile.

In Fig. 11, a hammer 7 is shown in a composite, in particular sandwich, construction, in which the harder cover layers 7.2 protrude over the softer core layer 7.1 in the area of the main, active wear. This design is intended to work towards the desired wear form (Fig. 10b and 12b) as a "self-sharpening ^" hammer 7 even before the actual wear.

The aim of all these measures on the hammers 7 according to Fig. 8 to 11 is to design them as active wear parts 7 by layers, layers or zones of different quality, hardness, toughness, thickness and/or shape so that in the state of wear they do not, as previously, take on a wear form according to Fig. 12a (longitudinal section of the hammer 7)

- 16 -

which has a "blunt" effect in the crushing process, but instead maintains its "self-sharpening" state until it is replaced - as shown in Fig. 10b and 12b. It was surprisingly found that this self-sharpening state has a beneficial and significant effect on increasing the service life of the active wear parts 7 as well as the crushing efficiency and leads to a coordinated wear behavior within the entire wear part system. With regard to the interaction with the inactive wear parts 8, this will be explained in more detail below.

The inactive wear part 8, a so-called protective cap, consists in the embodiment according to Fig. 13 of a composite of a cover part, referred to in the present context as cover surface 8.1, with a holder, which can be composed of a bearing hub 8.2 for fastening to the axle rods 6 (Fig. 1, 2, 3 and 7) and a web 8.3. Appropriate joints of the composite result from the representations according to Fig. 13a and b. To ensure a wear behavior corresponding to the active wear parts 7, the cover surface 8.1 is preferably constructed in multiple layers or multi-ply or equipped with different zones, so that the cover surface 8.1 has, for example, a relatively hard outer surface 8.4 compared to the composite parts, layers, layers or zones not directly exposed to wear.

Another inventive combination of cover surface 8.1 and holder 8.2, 8.3 is the design according to Fig. 14 with angled cover surfaces 8.1, which can also consist of angled, multi-layer surfaces or partial surfaces joined together at an angle.

To achieve a coordinated wear behavior between the active wear parts 7 and the inactive

• · 9 · · ♦

- 17 -

In a particularly favorable arrangement for the wear parts 8, which is shown for example in Fig. 6 (schematically developed) and Fig. 7 (simplified), the cover surface 8.1 is designed to be offset or notched according to Figs. 15 and 17, so that, as the top views in Figs. 15 and 17 show, they have different widths along their circumference. In the assembled state, this creates a coherent grid similar to the meander shape for a coordinated wear part system.

By equipping each inactive wear part 8 with several holders 8.2, 8.3 as shown in Fig. 15, 16 and 17, the service life of the arrangements for a wear part system according to the invention, as can be seen for example in Fig. 4, 5 and 6, can be increased even further. In these illustrations, the same capital letters indicate the same shape of the cover surfaces 8.1 and the number of holders 8.2, 8.3 per inactive wear part 8.

With the offset or notched cover surfaces 8.1 and holders 8.2, 8.3 between at least three adjacent disks 4, configurations of active and inactive wear parts 7, 8 can be realized according to the diagrams in Fig. 4, 5 and 6, which on the one hand effectively combine the advantages of the hammer 7 (Fig. 8 to 12) according to the invention with those of the protective caps 8 (Fig. 13 to 17) with regard to both the crushing process and favorable wear behavior, and on the other hand increase the efficiency of the crushing machine with regard to power consumption. Finally, according to the invention, wear parts are also provided that can be flexibly manufactured and variably adapted to the requirements of the wear material, and that active and inactive wear parts can be exchanged.

- 18 -

tive wear parts 7, 8 in a coordinated interval. In addition, quietly running rotor arrangements can be realized, which can be adapted to the respective feed material by means of a tunable wear part system, especially in cases in which, for example, inclusions of foreign matter are present, compaction for the subsequent process is to be avoided or even achieved and a favorable energy requirement is to be guaranteed.

Claims (29)

Protection claims: 1. Shredding machine with rotor, - which carries active and inactive wearing parts (7 and 8 respectively), - which, in their structure, shape, material composition and/or their mutual assignment, lead to a coordinated wear behavior. 2. Shredding machine according to claim 1, characterized by a rotor (2) consisting of discs (4). 3. Shredding machine according to claim 1 or 2, characterized in that at least one of the two types of wearing parts (7, 8) is joined in a composite construction. 4. Shredding machine according to claim 1 or 2, characterized in that at least one of the two types of wearing parts (7, 8) consists at least partially of layers, layers and/or zones (7.1 ₇ 7.2 or 8.3, 8.4) of different material properties, such as quality, hardness, toughness and/or thickness. 5. Shredding machine according to claim 3, characterized in that the active and/or inactive wearing parts (7, 8) are joined detachably and/or non-detachably. 6. Crushing machine according to one or more of claims 1 to 5, characterized in that the active wear parts (7) are rotatably mounted crushing tools (hammers) and the inactive Wear parts (8) (protective caps) cover at least the rotor parts (4) exposed to secondary wear. 7. Shredding machine according to one or more of claims 3 to 6, characterized _in that at least parts of the wearing parts (7, 8) are designed in sandwich construction. 8. Shredding machine according to one or more of claims 3 to 7, characterized in that the active wearing parts (7) are designed in a self-sharpening sandwich construction. 9. Shredding machine according to one or more of claims 1 to 8, characterized by a structural combination of several active and inactive wear parts (7, 8) with one another, wherein at least one active wear part (7) is carried between at least two inactive wear parts (8) and/or mounted on these and the inactive wear part (8) each comprises a wear region on a disk (4) which is essentially defined by the outer swing circle of the active wear part (7). 10. Active wearing part for a machine according to one or more of claims 1 to 9, characterized by several material layers (7.1, 7.2), of which at least one (7.2) is harder than the other(s) (7.1). 11. Wear part according to claim 10, characterized by two cover layers (7.2) with a core layer (7.1) in between. 12. Wear part according to claim 10 or 11, characterized in that the cover layers (7.2) have a greater hardness than the core layer (7.1) which is tough especially in the region of the bearing eye (7.3). 13. Wear part according to claim 11 or 12, characterized in that the cover layers (7.2) have openings extending to the core layer (7.1). 14. Wear part according to one or more of claims 10 to 13, characterized by a bell shape. 15. Wear part according to one or more of claims 10 to 14, characterized in that at least one cover layer (7.2) projects beyond the core layer (7.1) at the hammer edge. 16. Inactive wearing part for a shredding machine according to one or more of claims 1 to 9, preferably in combination with wearing parts according to one or more of claims 10 to 15, characterized by a joined composite of cover part or cover surface (8.1) and holder (8.2, 8.3). 17. Wear part according to claim 16, characterized by a polygonal shape of the cover surface or the cover part (8.1). 18. Wear part according to claim 16 or 17, characterized by a cover surface (8.1) of different width. 19. Wear part according to claim 18, characterized in that the cover surface (8.1) is notched in such a way that correspondingly notched cover surfaces of adjacent inactive wear parts can be fastened to the rotor to form a closed casing. 20. Wear part according to one or more of claims 16 to 19, characterized by several holders (8.2, 8.3) per wear part. 21. Wear part according to claim 20, characterized in _that the holders are axially aligned. 22. Wear part according to claim 20, characterized _in that the holders (8.2, 8.3) are circumferentially offset. 23. Wear part according to claim 20, characterized by the combination of axially aligned and circumferentially offset holders. 24. Wear part according to one or more of claims 20 to 23, characterized in that the holders protrude between at least three adjacent rotor disks. 25. Wear part according to claim 9 and one or more of claims 16 to 24, characterized by an axle pin on the holder, which together with an axle pin on an adjacent inactive wear part (8) forms a bearing for an active wear part (7). 26. Wear part according to claim 9 and one or more of claims 16 to 25, characterized in _that the holders (8.2, 8.3) each cover a wear area on the disks (4) which is essentially defined by the outer swing circle of the active wear part (7). 27. Wear part according to claim 26, characterized in that on the outer contours of the webs (8.3) open Recesses 2 are provided for fastening to the axle rods (6). 28. Wear part system for a shredding machine according to one or more of claims 1 to 9 with wear parts according to one or more of claims 1 to 24, characterized by an arrangement of the inactive wear parts (8) to form a substantially roller-shaped casing with openings or free spaces arranged offset from one another as desired for the active wear parts (7) to swing through. 29. Wear part system according to claim 28, characterized in that at least some of the inactive wear parts (8) cover sections of several rotor disks (4).