EP1289663B1 - Waste shredder, component parts and maintenance method - Google Patents

Description

The invention relates to a waste crusher such as birotor crusher of vehicle tires for example. It also relates to a mill rotor, and the shear wheel or wheels equipping said rotor. It extends to a method of maintenance of the waste crushers, comprising a method of repairing the knife plates ensuring the shearing of said waste, a method of dismounting said knife-plates for their repair, and, if necessary, a method of disassembling a rotor of the mill.

Known mills comprise at least one rotor composed of a plurality of shearing wheels, a shaft on which said wheels are fixed to drive them in rotation, and a plurality of spacers separating each two adjacent wheels. Each wheel comprises a support ring, fixed on the shaft, intended to carry the bodies ensuring the shear of the waste, said bodies forming teeth for driving and shearing waste on the periphery of the wheels. These bodies, subject to significant friction, wear out quickly, despite the use for their manufacture of particularly strong alloys. The shear wheels are of three types.

According to a first known type, proposed by US Pat. No. 4,854,508, each shear wheel comprises a plurality of knife plates, of axial dimension substantially equal to that of the crown-support, fixed on the peripheral face of the latter by fixing means accessible from the peripheral faces of said knife plates.

This type of wheel has the following disadvantage: worn knife plates whose cutting power has become insufficient can not be reused after regrinding. In fact, if a reduction in the radial dimension of a knife plate, after sharpening, can be compensated by adding a shim between the support ring and the knife plate, a reduction in its axial dimension can not be compensated by a similar system. However, in the most common case of twin-rotor mills, the cutting of waste is ensured not only by the overlap of the wheels of the two rotors of the mill (overlap which depends on the radial dimension of the wheels and therefore that of the knife plates), but also and above all by the minimization of the functional shearing clearance existing between two adjacent wheels (clearance depending on the axial dimensions of the knife plates). The frequent change of cutter plates and the impossibility of restoring and reusing used knife plates considerably increases the maintenance cost of these crushers.

According to a second type of known device, proposed by US Pat. No. 4,901,929, the lateral cheeks of the support rings each have a shoulder on which knives rest, extending radially beyond the peripheral face of the crown. support. Each knife is rigidly fixed on a side cheek of the crown-support by fastening means accessible laterally from holes in the knife located opposite, on the other side cheek of the crown-support. Unlike the first type of device described, the shearing members of this second type, namely the knives, can be detached from the wheel, restored (sharpened) and reused, subject to compensation, by shims interposed between the side cheeks of the crown-support and the knives, the consequent decrease in the sharpening of their axial dimension. But this device has the following disadvantage: the lateral fixing means of said knife on the crown-support are not very accessible, at least with conventional tools, by their arrangement and their lateral position on the wheel (when the wheel is mounted on its rotor, it is bordered by two neighboring wheels limiting the free space laterally). The removal of a knife for repair sometimes even requires complete disassembly of the rotor and its wheels. This operation therefore leads to a long and costly immobilization of the mill.

According to a third type of known device, each wheel comprises a relatively wide support crown having two radial extensions for fixing a knife, separated by a median space and each carrying on their outer lateral face a knife. The knives are fixed on these extensions by fastening means accessible from the above-mentioned median space, from the inner side faces of said extensions. Unlike the first type of device described, used knives are reusable after regrinding, provided to add a wedge of retrofit thickness as explained for the second device. The removal of a knife for repair is however a difficult operation for the same reasons as the previous device (limited accessibility of fixings knives). This operation therefore results in prolonged and costly immobilization of the mill.

Furthermore, it should be noted, in the case of the last two types of devices described, that the repair of worn knives requires precision and very tight machining tolerances. Indeed, the faces of the concerned knife and the catch are adjusted before mounting said knife and said wedge on the support ring. The functional shearing clearance obtained (clearance between a knife of a wheel of a rotor and the adjacent knife of the adjacent wheel located on the other rotor) thus depends on the machining tolerance of the shim, the tolerance rectifying the lateral faces of the knife, and the mounting tolerance of the wedge and the knife on the crown-support. All these operations must therefore be performed with particular care to obtain the desired shear functional play. The constraints related to the maintenance of the known mills (immobilization of the mill and severe tolerances) considerably increase the duration and the cost of the maintenance operations.

• obtenir avec précision et certitude, et de façon simple et rapide, le jeu fonctionnel de cisaillement souhaité lors de la réfection d'un couteau usé,
• simplifier les opérations de maintenance des couteaux, en rendant notamment les moyens de fixations des couteaux facilement accessibles et manoeuvrables, et en diminuant le nombre d'étapes nécessaires pour démonter un couteau,
• réduire le temps d'immobilisation d'un broyeur dû à une opération de réfection d'un couteau, afin de diminuer les coûts de maintenance,
• diminuer les coûts d'usinage des couteaux et cales de rattrapage d'épaisseur, en autorisant des tolérances d'usinage moins sévères,
• rendre possible le démontage d'un seul rotor en peu d'opérations.

The present invention, in these different embodiments, proposes to overcome the aforementioned drawbacks and to provide a new solution to each of the following objectives:

• obtain with precision and certainty, and in a simple and fast way, the functional shearing play desired during the repair of a used knife,
• to simplify the maintenance operations of the knives, in particular by rendering the means of fastening the knives easily accessible and manoeuvrable, and by reducing the number of steps necessary to disassemble a knife,
• reduce the downtime of a mill due to a knife repair operation, to reduce maintenance costs,
• reduce the machining costs of knives and wedges of compensating thickness, by authorizing machining tolerances less severe,
• make it possible to disassemble a single rotor in few operations.

Another object of the invention is to provide rotors compatible with the use of a comb adapted to remove the waste accumulating between the wheels of said rotor, waste which exerts a strong force resistant on the wheels in rotation and cause by therefore an overconsumption of energy.

Another object of the invention is to reduce the power consumed by these grinders, and thus achieve substantial energy savings.

• une couronne-support cylindrique, possédant deux joues latérales et une face périphérique définissant une pluralité de sections, ladite couronne-support étant adaptée pour être entraînée en rotation autour d'un axe par un arbre (la couronne-support peut présenter une âme creuse centrale pour permettre son montage sur ledit arbre, ou former une pièce unique avec ce dernier),
• une pluralité de couteaux de cisaillement possédant chacun une face latérale extérieure de cisaillement, chaque couteau étant disposé en correspondance avec une section de la face périphérique de la couronne-support de façon à venir radialement en saillie par rapport à ladite face périphérique.

For this purpose, the invention proposes a shear wheel for a waste crusher, comprising:

• a cylindrical support ring, having two lateral cheeks and a peripheral face defining a plurality of sections, said support ring being adapted to be rotated about an axis by a shaft (the support ring may have a central hollow core to allow its mounting on said shaft, or to form a single piece with the latter),
• a plurality of shear knives each having an outer shear side face, each knife being arranged in correspondence with a section of the peripheral face of the support ring so as to come radially protruding from said peripheral face.

• une pluralité de pièces porte-couteaux, comprenant chacune une face, dite face intérieure, de forme adaptée pour s'appliquer sur une section de la face périphérique de la couronne-support, une face, dite face extérieure, opposée à la face intérieure, et au moins une face latérale de fixation d'un couteau de cisaillement,
• des moyens de fixation amovible, adaptés pour permettre la fixation d'un couteau de cisaillement sur une pièce porte-couteaux et accessibles depuis la face latérale extérieure de cisaillement du couteau, ledit couteau étant adapté pour être fixé sur la pièce porte-couteaux en regard d'une face latérale de fixation de ladite pièce, en vue de former avec la pièce porte-couteaux un bloc rigide porte-couteaux/couteau(x),
• des moyens de fixation amovible, adaptés pour permettre la fixation d'une pièce porte-couteaux sur la couronne-support et accessibles depuis la face extérieure de ladite pièce porte-couteaux, en vue de permettre la fixation du bloc porte-couteaux/couteau(x) sur la couronne-support ou son retrait.

According to the present invention, said shear wheel is characterized in that it comprises:

• a plurality of knife-cutter pieces, each comprising a face, said inner face, of a shape adapted to be applied on a section of the peripheral face of the support-crown, a face, said outer face, opposite to the inner face, and at least one lateral side for fixing a shearing knife,
• detachable fastening means, adapted to allow the attachment of a shearing knife on a knife-cutter piece and accessible from the outer side shearing side of the knife, said knife being adapted to be fixed on the knife-piece next to of a lateral face of fastening said part, in order to form with the knife-cutter part a rigid knife / knife block (x),
• detachable fastening means, adapted to allow the fixing of a knife-holder part on the support ring and accessible from the outer face of said knife-holder part, in order to allow the fixing of the knife / knife block ( x) on the support ring or its withdrawal.

Thus, in the device of the invention, the removal of a knife requires only two steps, namely: the separation of the knife block / knife (x) from the crown-support, then the separation of the knife from the cutter piece. The first step is carried out without difficulty from the periphery of the wheel by a maneuver of the corresponding fastening means which are directly accessible without the use of special tools. The second step is performed without difficulty once the knife block / knives block separated from the wheel.

Advantageously and according to the invention, each knife is fixed on a knife-holder piece so that it extends radially at least as far as the outer face of said knife-holder part. In a preferred version of the invention, each knife has a shape and an arrangement adapted to come radially protruding from the outer face of the knife-cutter part, over an increasing height from upstream to downstream (by relative to the direction of rotation of the wheel) so as to form a tooth for driving and shearing the waste. The outer lateral edges of the knives, sharpened so as to be perfectly sharp, thus ensure optimized cutting of the waste, and the outer lateral faces of said knives complete the reduction of waste by shearing. It should be noted that the peripheral teeth formed by the knives make it possible both to perforate the waste, to perform their cutting, and to drive said waste into the mill.

Advantageously and according to the invention, each knife has a song, said inner edge, arranged to come in the axial extension of the inner face of the knife-holder part on which it is fixed, in order to avoid any accumulation of waste between said crown-support and said knife.

Advantageously and according to the invention, each knife has an inner edge of shape adapted to rest at least partly on a section of the peripheral face of the support ring, each knife-holder piece having an axial dimension smaller than the axial dimension of the crown-support.

• la tête présente au moins une face latérale de fixation d'un couteau en regard de laquelle est fixé un couteau,
• l'embase présente une face intérieure adaptée pour s'appliquer sur une section de la face périphérique de la couronne-support et au moins une face extérieure opposée à la face intérieure contre laquelle le couteau vient en appui.

In another embodiment of the invention, each knife-cutter piece has a base and a head of axial dimension smaller than that of the base, so that:

• the head has at least one lateral face for fixing a knife opposite which is fixed a knife,
• the base has an inner face adapted to be applied on a section of the peripheral face of the support ring and at least one outer face opposite to the inner face against which the knife bears.

Advantageously and according to the invention, each section of the crown-support supports a knife-holder part, and each piece-knife holder carries at least one knife, the knives being arranged around the crown-support so that two adjacent knives are contiguous, the outer side shearing faces of the knives forming a continuous shear lateral surface. In an advantageous embodiment, each knife-holder piece has two lateral fixing faces of a knife on each of which is fixed a knife so as to form two opposite opposite shear side surfaces around the circumference of the wheel. When the wheel is mounted on the rotor shaft of a twin-rotor mill, these lateral shear surfaces, when rotating, intersect with a functional shear play the lateral shear surfaces of the wheels of the other rotor. . The cutting power of the knives (sharp edges) and the minimization of the functional shearing clearance make it possible to grind extremely resistant waste, such as tires from vehicles (and in particular heavy goods vehicles), and determine an excellent efficiency of the crusher, combined with moderate energy consumption. The lateral shearing surfaces are preferably continuous in order to avoid any accumulations of waste between two contiguous knives.

According to one embodiment, the support ring has a circumferential face of cylindrical shape of revolution about the axis of rotation, the knife-carrying parts having cylindrical inner faces adapted to be applied to a section of said face. peripheral of the crown-support.

In an advantageous variant, the support ring has a polygonal peripheral face defining flat sections, each knife-carrying part having a planar inner face adapted to be applied on a section of the peripheral face of said support ring.

The invention also relates to a rotor for a waste mill, comprising at least one shear wheel as defined above, integral with a drive shaft in rotation of said wheel about an axis. In a preferred version of the invention, the rotor comprises a plurality of identical wheels regularly spaced along the drive shaft by spacers, each knife-carrying part of each of said wheels having two lateral fixing faces on each of which is fixed a knife, so as to form around said wheel two continuous opposed shear side surfaces. In general, the rotor also comprises two end wheels having only a continuous shear side surface, the knife parts of said end wheels bearing only one knife, presented towards the "inside" of the rotor.

The invention also relates to a waste crusher comprising at least two rotors as previously defined, of parallel axes, the adjacent wheels of said rotors being arranged on their respective shaft so as to interpenetrate and to have adjacent lateral shear surfaces. separated by a functional shearing game. The axes of the two rotors are separated by a distance less than the sum of the radius of a wheel of the first rotor and the radius of a wheel of the second rotor, so that the wheels intersect. Said wheels are spaced along their respective shaft so that part of the lateral shear surface of a wheel of a rotor constantly passes, with a functional shear play, a portion of the lateral surface shearing the adjacent wheel located on the other rotor.

• l'on sépare le bloc porte-couteaux/couteaux concerné de la couronne-support, en manoeuvrant les moyens de fixation reliant la pièce porte-couteaux à la couronne-support,
• l'on met en place et l'on fixe un nouveau bloc porte-couteaux/couteaux sur la face périphérique de la couronne-support, en manoeuvrant les moyens de fixation reliant la pièce porte-couteaux à la couronne-support.

The invention extends to a method of maintenance of a waste crusher as defined above; for the replacement or repair of at least one knife, characterized in that

• the respective cutter / knife block is separated from the support ring, by operating the fastening means connecting the knife holder part to the support ring,
• a new knife block / knife block is set up and fixed on the peripheral face of the support ring, by operating the fastening means connecting the knife-holder part to the support ring.

The new knife / knife block fixed on the support ring is advantageously a block waiting, ready to be used to replace the knife block / knives including the used knife. The replacement of the used block is in this case a very short operation, considerably reducing the downtime of the mill, and therefore the maintenance costs.

It is also possible to immediately reuse the used knife block / knife, replacing the knife concerned by a new knife according to the following method: said block being detached and separated from the wheel, the knife is separated from the knife-holder part by operating the fastening means connecting the knife to said piece, said knife is replaced by a new knife of suitable size and the latter is fixed on the knife-cutter part, by operating the fastening means connecting the knife to said piece, the new knife block / knife block obtained is set up and fixed on the support ring.

The used knife is reusable after grinding (sharpening) of its cutting and shearing surfaces, either immediately on the same knife block / knives, or later during another repair operation of one or more knives. For this purpose, the used knife being separated from the knife-cutter part, said knife is moved back to the cutter-knife part (or to another cutter-knife part in the case of subsequent use), by operating the means of cutting. fastening connecting the knife to said workpiece, after having inserted a squared piece, called wedge of correction of thickness, between said knife and said piece-knife-holders (against the external lateral face of this one) so that the knife block / shim / knife has a slightly larger axial dimension than desired; the outer side face of the knife is corrected so that the axial dimension of the knife / knife block corresponds to the appropriate dimension and the outer shearing face of the restored knife is at the desired distance from the knife part, set up and fix the block obtained on the peripheral face of the support ring. Said block can also be stored for later use during another maintenance operation. In this case, a new or previously restored knife / knife block according to the invention is put in place and fixed on the peripheral face of the support ring in replacement of the used knife / knife block removed, and the bearing block used knives / knives is restored as previously described, and stored waiting for reuse.

It should be noted that generally the two opposite knives of a cutter / knife part are ground during the same maintenance operation. A wedge of thickness adjustment is inserted between the knife part and each of the knives. The outer lateral shearing faces of the two knives are rectified one after the other as explained above.

In the device of the invention, the grinding of the shear faces and cutting faces or edges is an easy operation, and the regrinding or machining tolerances are less severe than those encountered for known mills. Indeed, the functional shearing clearance depends on the total axial dimension of the knife / knife block and the relative axial position thereof on the support ring. In the invention, the grinding of the external shearing face of a knife is advantageously done once the knife and its wedge mounted on the cutter-knife part. The block obtained can be fixed on a tool which is then positioned on a grinding machine: this tool reproduces the axial dimension of the support ring and is adapted so that the block comes to be arranged in accordance with its position on the support ring; the lateral faces of this tool thus serve as reference planes for performing the grinding of the knives. The two opposite knives of the knife block / knives are preferably rectified during the same maintenance operation, so that the total axial dimension of the block is the appropriate one. Thanks to the invention, the game functional shear depends only on two tolerances: the grinding tolerance of the outer side of the knives, which is a factory-made operation with high accuracy, and the mounting tolerance of the knife block / knives on the support ring . Unlike known grinders, it is not necessary to precisely machine the slip-up wedge, the machining tolerances of said wedge, the inner side face of the knife and even the external lateral face of attachment of the door part. -couteaux not affecting the final position of the external shearing face of the knife (except in the case of replacement of the used knife by a new knife not brought to undergo a correction of its outer side face).

In general, all the knives of a shearing wheel will preferably be restored during the same maintenance operation, so as not to create a discontinuity in the lateral shearing face of the wheel. In this case, all the knife blocks / knives are separated from the crown-support, and the two opposite knives of each piece-knife-holders are removed to allow the addition of a wedge between each of them and the cutter piece. The reconstituted knife / wedge / knife blocks are then fixed, by means of the fastening means usually connecting the knife-cutter pieces to the support ring, to a tool adapted to be mounted on a grinding machine, the plane containing said fasteners (or optionally the outer lateral faces of said tool) serving as a reference plane for grinding. The external lateral shearing faces of the knives located on the same side of the tooling are simultaneously ground. When the two sets of lateral shear faces (on either side of the tool) are ground, the blocks thus restored are removed from the tool and reassembled on the support ring of the shear wheel.

Finally, it should be noted that it is also possible and advantageous to rectify the external peripheral edges of the knives according to a method similar to that previously described, in order to brighten the outer lateral shear edges.

• l'on retire au moins une rangée de blocs porte-couteaux/couteaux axialement alignés, en manoeuvrant les moyens de fixation reliant chaque pièce porte-couteaux concernée à sa couronne-support,
• l'on fait subir au rotor une rotation autour de son axe, de façon que la rangée de sections de faces périphériques dépourvues de blocs porte-couteaux/couteaux soit située dans le plan contenant les axes de rotation des deux rotors,
• l'on fait glisser axialement le rotor jusqu'à son retrait du broyeur.

The invention also relates to a method of disassembly of a garbage disposal rotor according to the invention, characterized in that:

• at least one row of axially aligned knife-knife blocks is removed by operating the fastening means connecting each respective knife-holder part to its support ring,
• the rotor is rotated about its axis, so that the row of peripheral face sections without knife blocks / knives is located in the plane containing the axes of rotation of the two rotors,
• the rotor is axially slid until it is removed from the mill.

This method is particularly advantageous for mills in which the rotors are driven by two geared motors each located on any of the axial ends of said rotors, or by a gearbox having two outlets or a transfer box connected to one or two reducers, said Outlets or reducers being located on the same side of the mill and each connected to an axial end of the rotors.

The invention also relates to a waste grinder, some of its constituent parts and a method of maintenance of said grinder, characterized in combination of all or some of the characteristics mentioned above and below.

• la figure 1 est une vue de face d'un mode de réalisation d'un broyeur birotor de déchets conforme à l'invention, la majeure partie des organes étant coupée par un plan vertical passant par les axes des deux rotors,
• la figure 2 est une vue partielle en perspective d'un mode de réalisation d'un rotor selon l'invention,
• le figure 3 en est une vue latérale partiellement coupée selon un plan perpendiculaire à l'axe de rotation,
• la figure 4 en est une coupe de détail par un plan B parallèle à l'axe de rotation de la roue et passant par celui-ci,
• la figure 5 en est une coupe de détail par un plan A décalé par rapport au précédent,
• la figure 6 est une vue partielle en perspective éclatée illustrant le montage d'un bloc porte-couteaux/couteaux sur la couronne-support ou son retrait,
• la figure 7 est une vue partielle en perspective éclatée illustrant le montage des cales et couteaux sur une pièce porte-couteaux ou leur retrait.
• les figures 8 et 9 sont des coupes partielles d'un autre mode de réalisation par des plans parallèles à l'axe de rotation de la roue analogues aux plans A et B précités.

Other objects, features and advantages of the invention will appear on reading the description which follows, with reference to the figures of the accompanying drawings, which illustrate by way of nonlimiting example embodiments of the invention. On these drawings:

• FIG. 1 is a front view of an embodiment of a birotor waste crusher according to the invention, the majority of the members being cut by a vertical plane passing through the axes of the two rotors,
• FIG. 2 is a partial perspective view of an embodiment of a rotor according to the invention,
• FIG. 3 is a side view partially cut along a plane perpendicular to the axis of rotation;
• FIG. 4 is a detail section through a plane B parallel to the axis of rotation of the wheel and passing through it,
• FIG. 5 is a detail section through a plane A offset from the previous one,
• FIG. 6 is a fragmentary exploded perspective view illustrating the mounting of a knife / knife block on the support crown or its removal,
• Figure 7 is a partial exploded perspective view illustrating the mounting wedges and knives on a knife holder part or their removal.
• Figures 8 and 9 are partial sections of another embodiment by planes parallel to the axis of rotation of the wheel analogous to plans A and B above.

The waste shredder represented by way of example in FIG. 1 comprises two rotors 1 and 2 of parallel axes, each composed mainly of a shaft 3 (respectively 4) driven in rotation by a motor (not shown) and a plurality of identical wheels with each other, with the exception of the two wheels located at the ends of the rotors. Said wheels are rigidly mounted and fixed on the shaft 3 (respectively 4) and spaced apart by spacers 5.

Each wheel comprises a support ring 6, a plurality of knife-carrying pieces 7 distributed around its periphery and each carrying two opposed knives 8 and 9 (a single knife in the case of an "extreme" wheel) coming radially outwardly. said knife holder part 7, and possibly one (or two) spacer (s) of thickness 10. The rotational axes of the rotors 1 and 2 are separated by a distance less than the sum of the radius of a wheel the first rotor and the radius of a wheel of the second rotor, so that the wheels of the two rotating rotors interpenetrate. The wheels of a rotor are spaced along their shaft by an equal distance, with play, to the axial dimension of the knife block / wheel knives of the other rotor increased functional shearing play, so that the crossing of the wheels of the two rotors during their rotation causes the shearing of the waste.

Figures 2 and 3 respectively show two shear wheels of the same rotor, separated by a spacer, and one of said wheels. The support ring 6 of the wheel is fixed on the drive shaft 3 by keys 33. It has an outer peripheral face 29, in the polygonal example, defining flat sections 30, 31, ... receiving the knife blocks 7 / knives 8, 9.

Each knife-cutter part 7 is positioned on a section 30 of the support ring 6 by two centering pins 15 and 16, and is fixed on said section 30 by a central screw 17 accessible from the outer face 26 of the carrier part. knives 7, as shown in Figure 4. Each knife 8 (or 9) rests partly on a section of the peripheral face 29 of the crown-support 6 as illustrated in Figures 4 and 5, and is fixed on a piece knife holder 7 by two screws 11 and 13 (or 12 and 14) accessible laterally shown schematically in Figures 5, 6 and 7. It should be noted that only two bores and two screws are necessary and sufficient to position and fix each knife on a knife part, unlike the device described by US 4 901 929 of which each knife has no less than 8 bores and 4 fixing screws. The cost of manufacturing knives is considerably reduced.

The desired axial dimension L of the removable knife / knife block 34 is optionally obtained by the addition of one (or two) spacer (s) 10 of thickness adjustment. The left part of FIG. 4 (or FIGS. 5, 8 or 9) represents a knife 9 (or 40) having undergone a correction of its external lateral shearing face (presence of a compensating shim with a thickness of 10 - or 41). The right side illustrates the case of a new knife (no wedge). A knife block / knife block according to the invention could be represented by the left half of FIG. 4 (or of FIG. 8) and its symmetrical (case of a block comprising two shims and two rectified knives), or by the right half of said figure and its symmetrical (case of a block comprising two new knives and no shim).

It should be noted that the axial dimension of a knife / knife block may be greater than that of the crown-support so that the knives do not rest on the peripheral face of said crown-support. In this case, if the knives extend radially towards the shaft, facing the lateral cheeks of the crown-support, the axial dimension of the assembly piece-knife / wedge is preferably equal to that of the crown-support so that the inner side faces of the knives come against the side cheeks of the crown-support, thus preventing the accumulation of waste between said faces and said cheeks.

The parts involved in shearing and cutting waste, or parts particularly exposed to rubbing waste, namely knives 8 and 9 and knife parts 7, are made of materials particularly resistant to abrasion. In a possible embodiment of the invention, not shown in the accompanying drawings, the side cheeks 27 and 28 of the support ring 6 may also be protected by wear plates.

According to another embodiment of the invention, illustrated in FIG. 8, the blade holder piece 35 may comprise a head 36 of reduced axial dimension and a base 37 having a total axial dimension substantially equal to or slightly smaller than the axial dimension. L of the knife block / knives. On the base 37 abut the knives 39 and 40 and the catch-up wedges such as 41. The knife-cutter piece 35 is made of a material stronger than that of the crown-support 6: the part of the cheeks or lateral faces made of this resistant material therefore extends over a larger area in this embodiment than in the example illustrated in Figures 1 to 7. This embodiment eliminates any wear plates side. Another advantage of this embodiment is to ensure better fixing of the knives on their knife part since the base of the latter serves as seat knife.

The invention also relates to a method of maintenance of a waste crusher which is partially illustrated in FIGS. 6 and 7. In the device of the invention, the repair of a used knife 8 or 9 is a simple and rapid operation: the detachable knife / knife block 34 is disengaged by unscrewing the screws 17 connecting the knife-holder part 7 to the support ring 6. In order to avoid prolonged immobilization of the mill, a new knife / knife block is advantageously put in place and fixed on said support ring. Its position is adjusted by means of two centering pins 15 and 16 and firmly held by the screw 17. Then, its (or their) knife-cutting part 7 is separated from the knife (s) 9 (and / or 8). restore the removed block, unscrewing screws 11 and 13 (and / or 12 and 14). A shim 10 is interposed between the knife part 7 and a knife 9 (or the existing shim is changed for a shim of greater axial dimension), so that the axial dimension L of the knife block / knives 34 is greater than to the appropriate one. The block is mounted on a tool having a receiving face adapted to the inner face of said block, tooling intended to be fixed on a grinding machine for the grinding of each of the outer lateral shearing faces 18 and 21 of the two knives 8 and 9. Knife block / knife block 34 thus restored can be stored and used later, replacing another defective block.

Claims (19)

1. Shearing wheel for a waste grinder, comprising:

   - a cylindrical ring-support (6), which has two lateral cheeks (27,28) and a peripheral surface (29) which define a plurality of sections (30,31), the said ring-support being designed to be rotated around an axis by a shaft (3);

   - a plurality of shearing blades (8,9), each of which has an outer lateral shearing surface (18,21), each blade being disposed corresponding to a section (30) of the peripheral surface (29) of the ring-support (6), such as to project radially relative to the said peripheral surface, characterized in that the said shearing wheel comprises:

   - a plurality of blade-holder parts (7), each comprising a surface (23), known as the inner surface, with a shape which is designed to be applied to a section (30) of the peripheral surface (29) of the ring-support, a surface (26), known as the outer surface, which is opposite the inner surface, and at least one lateral surface (24) for securing a shearing blade (8);

   - detachable means for securing (11-14), which are designed to permit securing of a shearing blade (8,9) onto a blade-holder part (7), and are accessible from the outer lateral shearing surface (18) of the blade, the said blade being designed to be secured onto the blade-holder part opposite a lateral securing surface (24,25) of the said part, in order to form a rigid blade-holder/blade assembly (34) together with the blade-holder part; and

   - detachable means for securing (15-17), which are designed to permit securing of a blade-holder part (7) onto the ring-support (6), and are accessible from the outer surface (26) of the said blade-holder part, in order to allow the blade-holder/blade assembly (34) to be secured onto the ring-support, or removed from the latter.
2. Shearing wheel according to claim 1, characterized in that each blade (8) is secured to a blade-holder part (7) such that it extends radially at least as far as the outer surface (26) of the said blade-holder part.
3. Shearing wheel according to claim 1 or claim 2, characterized in that each blade (8) has a form and an arrangement which are designed to project radially relative to the outer surface (26) of the blade-holder part (7), at a height which increases from upstream in the downstream direction (relative to the direction of rotation of the wheel), such as to form a tooth (42) to drive and shear the waste.
4. Shearing wheel according to any one of claims 1, 2 or 3, characterized in that each blade (9) has an edge (20), known as the inner edge, which is designed to be placed in the axial extension of the inner surface (23) of the blade-holder part (7) onto which it is secured
5. Shearing wheel according to claim 4, characterized in that each blade (9) has an inner edge (20) with a form which is designed to be supported at least partly on a section (30) of the peripheral surface (29) of the ring-support (6), each blade-holder part (7) having an axial dimension which is smaller than the axial dimension of the ring-support.
6. Shearing wheel according to any one of claims 1 to 3, characterized in that each blade-holder part (35) has a base (37) and a head (36) with an axial dimension which is smaller than that of the base, such that:

   - the head has at least one lateral surface (43) for securing a blade, opposite which a blade (39) is secured; and

   - the base has at least one outer surface (45) against which the blade (39) is supported.
7. Shearing wheel according to any one of claims 1 to 6, characterized in that each section (30) of the ring-support supports a blade-holder part (7), and each blade-holder part (7) supports at least one blade (8), the blades being arranged around the ring-support (6) such that two adjacent blades are contiguous, the outer lateral shearing surfaces (18) of the blades forming a continuous lateral shearing surface.
8. Shearing wheel according to claim 7, characterized in that each blade-holder part (7) has two lateral surfaces (24,25) for securing a blade, onto each of which a blade (8,9) is secured such as to form two opposite continuous lateral shearing surfaces on the periphery of the wheel.
9. Shearing wheel according to any one of claims 1 to 8, characterized in that the ring-support has a peripheral surface with a cylindrical shape which revolves around the axis of rotation, the blade-holder parts having inner surfaces with a cylindrical shape which is designed to be applied to a section of the said peripheral surface of the ring-support.
10. Shearing wheel according to any one of claims 1 to 8, characterized in that the ring-support (6) has a polygonal peripheral surface (29) which defines flat sections (30,31), each blade-holder part (7) having a flat inner surface (23) which is designed to be applied to a section (30,31) of the peripheral surface of the said ring-support.
11. Rotor for a waste grinder, characterized in that it comprises at least one shearing wheel according to any one of claims 1 to 10, which is integral with a shaft (3) which rotates the said wheel around an axis.
12. Rotor for a waste grinder according to claim 11, characterized in that it comprises a plurality of identical wheels which are spaced regularly along the drive shaft (3), each blade-holder part (7) of each of the said wheels having two lateral securing surfaces (24,25) onto each of which a blade (8,9) is secured, such as to form around the said wheel two continuous opposite lateral shearing surfaces.
13. Waste grinder, characterized in that it comprises at least two rotors (1,2) according to claim 11 or claim 12 with parallel axes, the wheels of the said rotors being arranged on their respective shaft (3,4) such as to interpenetrate and to have adjacent lateral shearing surfaces which are separated by shearing play.
14. Method for maintenance of a waste grinder according to claim 13, for the purpose of replacement or restoration of at least one blade (9), characterized in that:

    - the blade-holder/blade assembly (34) concerned is separated from the ring-support (6), by manoeuvring the means for securing (17) which connect the blade-holder part (7) to the ring-support; and

    - a new blade-holder/blade assembly is put into place and secured to the peripheral surface (29) of the ring-support, by manoeuvring the means for securing (15-17) which connect the blade-holder part (7) to the ring-support (6).
15. Method for maintenance according to claim 14,
    characterized in that:

    - the blade-holder/blade assembly (34) concerned having been detached and separated from the wheel, the blade(s) (9) is/are separated from the blade-holder part (7) by manoeuvring the means for securing (11) which connect the blade to the said part;

    - the said blade is replaced by a new blade, and the latter is secured to the blade-holder part (7) by manoeuvring the means for securing (11) which connect the blade to the said part; and

    - the new blade-holder/blade assembly obtained is put into place and secured to the ring-support (6).
16. Method for restoration of a blade-holder/blade assembly, characterized in that:

    - the blade-holder/blade assembly (34) concerned having been detached and separated from the wheel, the blade (9) is separated from the blade-holder part (7) by manoeuvring the means for securing (11) which connect the blade to the said part;

    - a squared part, known as a wedge (10) is put into place against the outer lateral surface (25) of the blade-holder part;

    - the blade (9) concerned is positioned against the said wedge, and the wedge/blade assembly is secured to the blade-holder part, by manoeuvring the means for securing (11) which connect the blade to the said part; and

    - the outer lateral shearing surface(s) (21) of the blade(s) (9) is/are ground such as to adjust the axial dimension L of the blade-holder/blade assembly (34) and the position of the said outer lateral shearing surface (21) relative to the blade-holder part (7).
17. Method for maintenance of a waste grinder according to claim 14, characterized in that:

    - the blade-holder/blade assembly (34) concerned is restored according to the restoration method in claim 16; and

    - the new blade-holder/wedge/blade assembly obtained is put into place and secured to the ring-support (6).
18. Method for maintenance of a waste grinder according to claim 14, characterized in that:

    - a new or previously restored blade-holder/blade assembly is put into place and secured on the peripheral surface (29) of the ring-support (6), by manoeuvring the means for securing (15-17) which connect the blade-holder part (7) to the ring-support;

    - the worn blade-holder/blade assembly (34) removed is restored according to the restoration method in claim 16; and

    - the blade-holder/wedge/blade assembly obtained is stored for the purpose of using it for a subsequent maintenance operation.
19. Method for dismantling a rotor of a waste grinder according to claim 13, characterized in that:

    - at least one row of axially aligned blade-holder/blade assemblies (34) is removed by manoeuvring the means for securing (15-17) which connect each blade-holder part concerned to its ring-support;

    - the rotor is rotated around its axis, such that the row of sections (30) of peripheral surfaces without blade-holder/blade assemblies is situated on the plane which contains the axes of rotation of the two rotors; and

    - the rotor is slid axially until it is withdrawn from the grinder.

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