Material shredder with grinding device, shredding unit and maintenance method

Abstract

The invention relates to a material shredder (1), in particular for shredding recyclable cut material, with a rotatably mounted rotor, designated as cutting head (10), on which a plurality of axially extending cutting blades (11) are arranged, which are spaced apart from one another in the circumferential direction and have radially outer cutting edges (12) forming a cutting circumference, having a rotor housing, designated as stator (20), which substantially surrounds the cutting head (10), wherein the stator (20) and the cutting head (10) define a cutting chamber (3) arranged therebetween, into which the cutting blades (11) and at least one counter blade (23) arranged on the inner circumference of the stator (20) project, wherein the counter blade (23) is arranged at a radial distance from the cutting circumference to form a cutting gap (4), and wherein the stator (20) has at least one outlet (22) in which a screen (24) delimiting the cutting chamber (3) is arranged. According to the invention, the material shredder (1) has a grinding device (30) with an abrasive holder (31) holding an abrasive, wherein the grinding device (30) is arranged outside the cutting circumference, and the abrasive and the screen (24) are movable in position in such a way that the respective radial distance to the cutting circumference can be adjusted as desired. The invention also relates to a comminuting plant (100) with a material shredder (1) and to a maintenance method.

Description

[0001] "Material shredder with grinding device, shredding system and maintenance procedures"

[0002] Description:

[0003] The invention relates to a material shredder according to the features in the preamble of claim 1, which is intended for shredding cuttings, in particular (recyclable) cuttings such as waste materials, (fiber-containing) plastics, or the like. The cuttings or shredded material may contain impurities, for example, silicate-containing substances or the like. Furthermore, the cuttings are not uniformly aligned when fed to the material shredder.

[0004] Generic material shredders, in particular cutting mills or the like, have been known for a long time. Such material shredders always have a substantially vertical or horizontal, rotatably driven cutting head, whereby the term "cutting head" is used here collectively for a rotor in the form of a drum, a roller or the like, or for a rotor having one or more rotor blades. A plurality of shredding tools, in particular cutting blades, are usually arranged on the cutting head, wherein the cutting edges of the cutting blades form a cutting circumference when the cutting head rotates. In the cutting area, i.e., the outer circumference of the cutting circumference, the cutting blades can be made of different materials, for example tungsten carbide or the like.

[0005] The cutting head is surrounded at least in part by a rotor housing, referred to herein as the stator. The stator surrounds the rotatably mounted cutting head, with one or preferably several stationary counterblades arranged on the inner circumference of the stator. The stator is usually designed as an at least partially cylindrical housing that defines the space surrounding the rotor, referred to as the cutting chamber. The material to be cut is shredded in the cutting gap, which is formed as the radial distance between the cutting edge and the counterblade.

[0006] Cuttings are introduced into the cutting chamber through an inlet in the stator, and the shredded cuttings are removed from the cutting chamber through an outlet in the stator (due to centrifugal force). Conveyor systems are known that force the cuttings to be fed actively, partially pushing the cuttings into the cutting periphery.

[0007] In a particularly simple design, the inlet can be the same as the outlet. A conveyor system and / or a collecting device can be provided adjacent to the outlet to convey or collect the shredded cuttings. A (perforated) screen arranged in the outlet and limiting the size of the cutting chamber serves to determine the regularly fine size fractions for the shredded cuttings discharged from the cutting chamber, such that the cuttings are shredded until they can pass through the screen. Screen sizes of up to approximately 100 mm are particularly common. In conjunction with the counter knife, the screen means that the cuttings are sometimes cut several times, whereby the cuttings are generally not subject to any defined positional orientation in the cutting chamber.

[0008] When shredding material, the cutting and counterblades of a shredder are subjected to diverse stresses, particularly when silicate-containing deposits or similar are present on the material. The edge radius of the blades, which is crucial for shredding, i.e., the radius at the cutting edge created by the two surfaces of the blade meeting each other, increases with increasing wear, which, for example, increases the required shredding energy. Cutting edge wear also causes the cutting gap to enlarge. As a result, the cutting quality and / or edge retention decrease, as the material is increasingly crushed and / or torn apart, which, for example, leads to an increase in the unwanted dust content with very small particle sizes in the material.

[0009] In order to ensure sufficient, consistent cutting performance while using moderate energy consumption and to reliably convey the cut material through the screen, it is necessary, on the one hand, to regularly sharpen the cutting blades and, if necessary, the counterblades, i.e., to reduce the cutting edge radius. On the other hand, the counterblades, in particular, must be readjusted to keep the cutting gap as constant as possible to ensure sufficient cutting performance.

[0010] DE 865 249 B discloses a generic material shredder, wherein, to improve cutting performance, it is proposed to arrange the cutting blades and counterblades at an angle to the rotational axis and at an angle to each other in order to achieve a scissor-cut shredding of the material in the manner of a tangential cut. The inventive, screw-like design of the cutting blades is problematic with regard to regrinding the cutting blades. It is now common practice to arrange the blades in such a way that the material is shredded by means of a tangential cut, for example, to reduce the load on the blades or to extend their service life. It is also well known to provide the cutting edges with particularly hard surfaces or the like in order to extend their service life.Ultimately, however, all existing shredders share the problem that regrinding the cutting or counterblades results in a particularly economically disadvantageous shredder downtime, as the blades have to be removed for sharpening, which is time-consuming, labor-intensive, and error-prone. Downtime is particularly disadvantageous in that the shredder is often a central component within a larger processing unit, rendering the entire processing unit unproductive during shredder maintenance.During the removal and installation of the knives, it is also necessary to carefully clean the knife holders in which the knives are releasably fixed, so that no residues remain which could lead to tearing or breaking of a fixed knife, particularly in the case of uneven force connection when clamping the knives, or which could cause increased stress on the cutting edge in certain sections during the cutting process.

[0011] The present invention is based on the object of proposing a material shredder which can be operated economically advantageously with longer service lives without the cutting ability, i.e. the cutting quality, being impaired or a higher energy expenditure being required for shredding cuttings, in particular recyclable waste materials, (fibre-containing) plastics, or the like.

[0012] The object is achieved by a material shredder according to the features of claim 1, by a shredding plant according to the features of claim 15 and by a method according to claim 18.

[0013] Features of the invention are described below. These design features can be implemented in conjunction with the invention or can be independently inventive, independent of the invention. They can be implemented either individually and independently of one another or in any combination, including the implementation of all of the aforementioned features, unless a combination is expressly or technically mandatory.

[0014] In other words, the invention proposes a device for comminuting cutting or shredding material, namely a material shredder. Essential to the invention is a grinding device that allows the cutting blades on the cutting head, in particular the cutting edge, to be ground while the cutting head is rotating, so that prolonged downtime of the material shredder can be economically avoided, since a comparatively high cutting edge retention, i.e., high cutting quality, can be ensured even without removing the cutting blades. The risk of blade failure is also reduced, since the clamping of a blade is not always manually adjusted after grinding. Furthermore, the rotation during grinding can create an ideal geometric, essentially cylindrical cutting circumference, so that the cutting edges of several cutting blades are each arranged circumferentially on the same circular path.

[0015] According to the proposal, the grinding device is arranged with an abrasive holder holding an abrasive outside the cutting periphery, preferably radially outside the cutting periphery. The abrasive holder can have a grinding wheel, an abrasive carrier, or the like, which are connected to the abrasive. The abrasive is particularly preferably detachably connected to the abrasive holder, for example by means of an adhesive, bonding, snap-in, or plug-in connection, or the like, in order to be able to replace the abrasive relatively easily as the abrasive wear increases.According to the invention, the abrasive means is positionally movable so that it can be selectively moved from a non-grinding rest position, in which the abrasive means is arranged outside the cutting circumference, into a grinding-effective, approximate grinding position, in which the abrasive means is in engagement with the cutting edges of the cutting blades and preferably causes a substantially tangential bevel of the cutting edges to the cutting circumference, thus sharpening the cutting blades.

[0016] According to the invention, the screen, which can occupy a significant circumferential section of the stator, is also positionally movable, such that the cutting space can be changed in size and thus the distance between the cutting circumference and the screen. As material removal increases during regrinding of the cutting blades, the distance between the screen and the cutting circumference generally increases. This is problematic in that the cutting blades also serve to drive the cut material through the screen, provided the cut material can pass through the screen. As the distance between the screen and the cutting circumference increases, the cut material is increasingly crushed and the required drive energy of the cutting head increases. Surprisingly, the positional mobility of the screen makes it possible to avoid these disadvantages and reduce the stress on the cut material.

[0017] It can be provided that one or more positionally movable sieves are arranged. Furthermore, a sieve can be essentially one-piece or segmented, so that several sieve elements form a sieve. The sieve elements in the outlet can be aligned at an angle to one another. Alternatively, the sieve elements can be circularly arc-shaped, at least in sections, so that several sieve elements create a larger circular arc.

[0018] In one embodiment, the grinding device can have a guide, for example in the form of a guide rail, a guide track or the like. A straight guide is particularly preferred, which is advantageously aligned essentially parallel to the longitudinal or rotational axis of the cutting head, and the abrasive holder is arranged on the straight guide so that it can be displaced along the cutting blades, and in particular so that it can be displaced essentially in a grinding-effective manner. A grinding carriage, grinding truck or the like, mounted for example on rollers, can be arranged on the guide rail and displaceably connects the abrasive holder to the straight guide. The straight guide with grinding carriage serves to be able to guide an abrasive back and forth, in particular in a grinding-effective manner, along the longitudinal axial extent of the cutting blades in a pendulum motion.Pendulum grinding, for example, prevents scoring on the cutting edges of the cutting blades. Furthermore, the cutting blades can be reground very evenly, creating a uniform cutting circumference across the entire length of the cutting blade. The area within which the abrasive engages the cutting blades is referred to here as the grinding zone.

[0019] Advantageously, the grinding carriage, grinding carriage or the like is driven mechanically, hydraulically, pneumatically or electrically, for example by means of a chain drive, tow rope drive or the like.

[0020] In a very simple embodiment, the abrasive can be held in a holder in a rotationally fixed manner on the abrasive holder. In a preferred further development, the holder can hold the abrasive in a rotationally movable manner, so that the abrasive can preferably rotate about a rotation axis that is aligned substantially perpendicular to the cutting head rotation axis. The holder can be designed, for example, in the manner of a cup wheel. The abrasive can be arranged on a cross-sectional surface and is rotationally driven via the holder, so that the abrasive rotates, for example, during the pendulum movement with and / or against the direction of rotation of the cutting head. The rotational speed of the abrasive is preferably slower than the rotational speed of the cutting head.

[0021] As an alternative to the cup wheel, the abrasive holder can have a rotationally driven abrasive wheel which is aligned substantially parallel to the rotation axis of the cutting head and at least on the circumference of which an abrasive is arranged so that an abrasive can be rotated either with or against the direction of rotation of the cutting head.

[0022] The rotation of the abrasive can involve one or more complete rotations of the abrasive around its own axis of rotation, and the cutting blades can be sharpened during this rotation of the abrasive. It can also be provided that the abrasive rotates discontinuously around a circular arc, so that the cutting blades are at least temporarily ground with a non-rotating abrasive. Partial rotations of 3 to 270° are advantageous, particularly preferably 5 to 30°. Any (partial) rotation of the abrasive is referred to herein as rotation. Furthermore, it can be provided that the abrasive rotates outside and / or inside the grinding zone.

[0023] To enhance the positional mobility of the abrasive, the grinding device can particularly advantageously have an abrasive infeed, preferably on the straight guide, abrasive holder and / or the abrasive holder. During the infeed, an abrasive is selectively moved towards the cutting edge of the cutting blade or the radial distance of the abrasive from the cutting head is reduced. To increase the effectiveness of the abrasive, it may be sufficient for the abrasive to rotate so that at least sections of the abrasive are brought closer to the cutting circumference or are brought into engagement with the cutting blades. An infeed with grinding effectiveness, i.e. an infeed when the abrasive is in engagement with the cutting circumference in the grinding zone, is referred to herein as working grinding or grinding out, whereby grinding without infeed is referred to as sparking out.

[0024] The abrasive feed can be provided to transfer the abrasive from a spaced-apart rest position to a grinding position where it is effective for grinding and / or, in addition, to define the intensity of material removal during grinding, with the feed preferably being continuously variable. For this purpose, the feed can, for example, have one or more feed screws, via which the radial distance can be adjusted. Alternatively or additionally, hydraulically or pneumatically driven cylinders or the like can be provided to feed the abrasive or to move the abrasive into a rest position.

[0025] A particularly inventive development can relate to a nozzle unit on the grinding device. One or more preferred suction nozzles, suction nozzles, or the like, collectively referred to herein as suction nozzles, serve to remove any grinding dust directly from the grinding zone. For this purpose, the suction nozzles are aligned with the cutting periphery in a suction-effective manner, i.e., the suction effect of the suction nozzles extends essentially to the cutting periphery. Advantageously, the nozzle unit is connected to a collection unit in which the grinding dust is collected. This prevents grinding dust from contaminating the comminution material. Alternatively or additionally, application nozzles can be provided, which, for example, supply a cooling fluid or the like to the cutting periphery.

[0026] In a further embodiment, the screen can be pivotally mounted, preferably parallel to the rotational axis of the cutting head, so that, on the one hand, the screen can be pivoted out of the outlet in order to expose it, so that, for example, the cutting head or the stator can be easily cleaned. On the other hand, the pivotally mounted mounting can enable the radial distance of the screen from the cutting head, and thus the size of the cutting chamber, to be optionally adjusted in the manner of a screen feed. Such a screen arrangement is advantageous in order to ensure a largely homogeneous distance between the cutting circumference and the screen, so that, concomitantly, economically efficient energy consumption for driving the cutting head and only minimal effects on the material properties of the material to be cut, for example on the elastomechanical strength, can be achieved.

[0027] To adjust the distance and to secure the screen, a screen holder can be provided which is pivotally mounted and acted upon by an adjusting device arranged outside the cutting chamber. Advantageously, the adjusting device can have a feed pin which is preferably held so as to be continuously movable, essentially in the radial direction, is connected to the screen holder and defines the approach of the screen to the cutting circumference. Alternatively or additionally, a pneumatically or hydraulically driven cylinder or the like can be provided with which a pivoting extent of the screen holder or the screen can be adjusted. The screen can usually have a substantially rectangular shape which is curved according to the diameter of the cutting head or the stator, wherein in this case the screen is held so as to be pivotable over a non-curved longitudinal side.It can be provided that the screen has a tapered material thickness that decreases in cross-section at one end, specifically on the opposite longitudinal side, in an edge region of the screen, referred to here as the transition zone. At least in the transition zone, the stator and screen are arranged to overlap one another, with the screen being arranged radially inward. Preferably, the material thickness decreases in the direction of rotation of the cutting head so that cutting material does not accidentally become stuck in the cutting chamber. The tapered overlap of screen and stator in the transition region supports a screen feed that is adapted to the material removal caused by grinding.

[0028] A further development of the invention can comprise a control unit that is connected to the grinding device for signal transmission, in particular to the abrasive feed, so that an infeed dimension can preferably be programmed. Alternatively or additionally, the control unit can regulate the pendulum movement with which the abrasive is guided along the cutting blades. An operating element is advantageously connected to the control unit, with which an operator can, for example, define an infeed or an infeed program. Alternatively or additionally, sensors can be provided that detect the drive power of the cutting head or the like in order to be able to draw conclusions about the wear of the cutting blades and to initiate regrinding of the cutting edges, preferably in an automated manner. For this purpose, the control unit can preferably be designed to control the cutting head rotation.In a particularly advantageous, inventive embodiment, the stator can have one or more point-like and / or linear guide elements in the form of projections, noses, guide ribs, lips, or the like, projecting radially into the cutting chamber outside the cutting circumference. The guide elements can serve to align the cut material, in particular film fragments, film strips, or the like, as the cutting head rotates. As a result, among other things, the migration of the cut material on the screen is reduced and the cutting edge retention and cut material discharge from the cutting chamber are improved, so that the cutting edges of the cutting blades are subjected to less stress and, consequently, the service life of a material shredder can be extended. In a particularly advantageous embodiment, guide elements can be arranged on the screen.

[0029] One indicator for detecting cutting edge wear can be the cutting material after it has exited the cutting chamber. In the case of advanced wear, the cutting material is usually characterized by fibrous, frayed cutting surfaces. Furthermore, the dust content, i.e. the proportion of small cutting material particles, increases. Therefore, a further development can provide optical cutting material detection, for example a camera that records key features such as the geometry of the cutting material, the surface properties, or the like, and preferably evaluates them using software. If a recorded actual value deviates excessively from a stored target value, an alarm can be triggered, for example, informing a user of the need for regrinding. Alternatively, an alarm signal can be transmitted to the control unit, which automatically initiates regrinding.

[0030] Alternatively or additionally, the dust content in the outlet stream can be detected electrically, for example, by means of resistance measurement or by means of a classifying process. The dust content is first separated and then its weight is determined. As already mentioned, sensors can be provided that measure the power consumption of the drive unit for the cutting head. An increased power consumption of the drive unit usually indicates advanced wear of the cutting edges. In response to detected or inferred cutting edge wear, a user-initiated grinding process or, more preferably, an automated grinding process using a control unit can be performed.

[0031] An acoustic sensor, such as a knock sensor, can be particularly advantageous. This sensor is designed to detect the structure-borne vibrations that occur when a cutting blade passes a counterblade. The size of the cutting gap generates a characteristic acoustic signal, which is generally or sensorially perceptible as a knock. This makes it easy to acoustically determine the wear of the cutting edges and, if necessary, respond with regrinding, either manually or automatically as explained above.

[0032] In particular, an acoustic sensor such as a knock sensor or similar can be used alternatively or additionally to determine the distance between the abrasive and the cutting periphery. This distance can be important, for example, during the advance of the abrasive. If the advance is too fast or the abrasive engages the cutting periphery too deeply, there is a risk of damage to the material shredder.

[0033] In one embodiment, the material shredder can have a metal sensor that detects metallic components in the shredded material. Such components are advantageously detected before they are fed into the cutting chamber to prevent any damage, such as chipping of the cutting blades or the like. For this purpose, the metal sensor can be connected to the control unit, which, when metallic components are detected, stops the feed of the shredded material into the cutting chamber and / or stops the cutting head.

[0034] One key element for edge retention is, among other things, the size of the cutting gap between the cutting circumference and the counter-blade. Advantageously, a blade holder can be provided in which a counter-blade is detachably secured to the stator, wherein the blade holder is movable relative to the cutting head so that the counter-blades can be brought closer to the cutting circumference, preferably continuously. Particularly preferably, regardless of the further development of the blade holder, the material shredder in the present case can have at least two counter-blades. Preferably, the blade holder can be motor-adjustable, for example by means of a linear motor with an adjusting spindle, wherein the drive is preferably connected to the control unit for automated adjustment of the cutting gap in a signal-transmitting manner. The counter-blade is preferably held in the blade holder by clamping, for example by means of disc springs and / or hydraulic press clamping.This eliminates the need for manual adjustment, extending the service life. To allow for manual adjustment of the counterblades, the blade holder can be equipped with adjustment screws to define the cutting gap.

[0035] In a further development of the invention, a knife holder can have so-called knife seats for several counter knives, wherein a counter knife is preferably screwed into a knife seat and the knife holder is mounted for rotation, so that a first knife seat with counter knife can be selectively aligned in an operating position that creates a cutting gap or in a rest position. In this way, setup times can be significantly shortened by allowing a first counter knife to operate in the operating position while a second counter knife of the knife holder can be serviced, in particular, ground.

[0036] In a particularly advantageous embodiment, alternatively or in addition to the nozzle unit, a suction device can be provided, which is connected to the outlet and has a suction flow effect, so that the clippings can be sucked from the cutting chamber through the screen into the outlet and finally, for example, into a collecting device. The suction supports the continuous removal of clippings from the cutting chamber, so that the clippings can be shredded with a high cutting accuracy and, for example, blockages or the like in the cutting chamber or screen can be avoided.

[0037] In addition, a suction device can be advantageous in order to be able to suck up grinding dust during a grinding process. This can prevent contamination of the cut material, for example when the cutting head is rotating and the cutting blades are being sharpened, but there is no cut material in the cutting area. In a further development, a suction device can be provided which sucks the grinding dust directly from the abrasive. For this purpose, for example, a suction nozzle can be provided on the grinding device which is connected to the suction device in a suction flow-effective manner. By arranging a filter in the suction flow or the like, the grinding dust can be separated from the suction flow, so that in principle the cut material can be shredded during grinding without the cut material becoming contaminated. This can be economically advantageous because the service life of the material shredder can be extended.A particularly preferred embodiment with one or more of the features described herein relates to a material shredder in the form of a cutting mill. Cutting mills are used, in particular, to provide particularly fine material fractions after cutting, advantageously with a maximum edge length substantially less than 100 mm, preferably substantially in the range of 20 to 100 mm, particularly preferably substantially less than 20 mm.

[0038] Furthermore, a waste material shredding system is proposed, comprising a shredding device, which is a material shredder, in particular a cutting mill, having the proposed features and optionally having the features corresponding to the previously described further developments or the like. The proposed shredding system also comprises a feed device, which transfers the shredded material, for example, in the manner of a hopper arrangement or the like, into the material shredder, without any significant loss of shredded material. Furthermore, the shredding system can advantageously comprise a discharge device, which conveys the material shredded by the material shredder, for example by means of a screw conveyor, slide, air stream, or the like.

[0039] In one embodiment, the shredding plant can have at least one cuttings container into which the shredded cuttings are conveyed after passing through the sieve.

[0040] A further development can advantageously provide a dosing device arranged on the feed device in order to be able to feed the cutting material into the cutting chamber as needed. Firstly, this can prevent blockages or the like in the cutting chamber. Secondly, the cutting material feed can be designed in terms of quantity so that optimal utilization of the cutting head's drive power can be achieved, for example through a homogeneous load situation. Thirdly, a substantially homogeneous drive power can contribute to the early detection of wear on the cutting blades and the ability to react as needed, for example by grinding. Fourthly, a dosing device can create a type of buffer storage, particularly when intervals of feeding with cutting material are planned, for example by means of an industrial truck, wheel loader or the like.

[0041] Advantageously, a conveyor system can be provided that forms a conveyor line that leads into the feed system. By means of the conveyor system, the clippings can be conveyed and fed in a largely continuous manner. In this sense, the conveyor system can also, or in particular, function as a metering device for a demand-adapted supply of clippings.

[0042] The invention further relates to a maintenance method for a material shredder, in particular for (re)establishing the operational capability of the material shredder, wherein an abrasive is applied to a cutting edge of a cutting blade, the abrasive is guided along the cutting blade, and a screen is applied to the cutting head, wherein the cutting head rotates at least during grinding. The material shredder preferably has one or more of the features described above.

[0043] In the sense of infeed, an abrasive is, on the one hand, as previously described, brought from a non-grinding arrangement into engagement with a cutting edge of a cutting blade, wherein the cutting blade is arranged axially extending on a rotatably mounted rotor of the material shredder, referred to as the cutting head. As soon as the abrasive is engaged with the cutting edge, material can be removed at the cutting edge to reduce the cutting edge radius. On the other hand, the material removal can be defined by means of infeed such that with increasing infeed, i.e., the abrasive is brought radially closer to the cutting head, greater material removal is achieved, particularly at the cutting edge.

[0044] According to the proposal, the abrasive is guided along the cutting blades in a grinding manner, preferably several times in a pendulum motion back and forth, whereby it is crucial that the cutting head rotates. Because the cutting edges can be machined, i.e., ground, while the cutting head rotates, the service life of a material shredder can be extended in a cost-effective manner. Disassembly of the cutting blades before grinding and subsequent, cost-intensive assembly of the sharpened cutting blades are no longer necessary. Furthermore, the rotation during grinding creates an ideal geometric, essentially cylindrical shape of a cutting circumference, so that the cutting edges of several cutting blades are each arranged circumferentially on the same circular path.

[0045] The proposal involves reducing the distance between a screen and the cutting head or cutting blade, with the screen being located in an outlet of the stator. Reducing the distance ensures that the material to be cut continues to be conveyed through the screen after the cutting blades have been ground, ensuring consistent cutting performance. The screen can be advanced essentially simultaneously with the grinding process.

[0046] In a further development of the process, a radial advance of one or more counter knives can be provided. These are arranged on the inner circumference of the stator surrounding the cutting head, so that a substantially constant cutting gap can be achieved between the counter knife and the cutting edge. Since material is removed from the cutting edges during grinding, it may be necessary to adjust the radial distance between the counter knife and the cutting knife or cutting head. A largely constant cutting gap contributes to extending the service life of the cutting knives, thus reducing maintenance requirements and extending service life.

[0047] The present invention is based on the idea of ​​proposing an economically advantageous solution. Extensive automation can make a significant contribution to this. In a particularly inventive further development, the method steps can therefore be carried out in a controlled manner, i.e. coordinated with one another and particularly preferably automatically. A control unit first evaluates a signal which induces increased cutting edge wear by detecting a deviation between an actual value and a target value. The power consumption of the cutting head and / or the cutting quality or the dust content or the like can be used as indicators of increased cutting edge wear. If increased wear is detected, the control unit then initiates grinding of the cutting blades. For this purpose, the control unit controls the feed of the abrasive and the guidance of the abrasive along the cutting blades.Grinding is suspended as soon as the target cutting quality is achieved again and / or after the cutting blades have been ground based on a known grinding experience, whereby, for example, a certain number of pendulum movements and / or a certain grinding duration may be decisive. Because grinding takes place during the cutting head rotation, with the speed of the cutting head rotation being adjustable accordingly, the cutting quality can be verified immediately, without the need for laborious installation and / or removal of the cutting blades.

[0048] It is particularly advantageous to extract the grinding dust during grinding. For this purpose, the control unit can regulate a suction device or the like. Furthermore, the control unit can initiate the application of coolants or the like to cool the cutting blades during grinding.

[0049] Furthermore, it can preferably be provided that the control unit regulates the feed of the counter knives depending on the grinding intensity. For this purpose, the control unit can, on the one hand, process a signal from which the grinding-related material removal can be derived. On the other hand, it can be provided that the control unit processes a signal from which the distance between the counter knife and the cutting circumference can be derived.

[0050] Alternatively or additionally, the control of the maintenance steps can follow a predetermined (time) interval, whereby the individual process steps are particularly preferably controlled by means of a control unit.

[0051] Advantageously, it can be provided that the counter knife is ground, in particular manually ground, before the counter knife is fed.

[0052] The described process steps can be performed sequentially. It can also be performed for some or all of the process steps to be performed at least partially simultaneously. For example, the radial feed of the abrasive can take place (step a) while the cutting blades are ground (step b). Furthermore, the radial sieve feed (step c) can take place while the abrasive is fed and / or the abrasive grinds the cutting blades.

[0053] Counter knife feed (step d) can start or be completed after completion of steps a) to c) or even during one of steps a), b) or c).

[0054] An embodiment of the invention is explained in more detail below using the purely schematic representation, whereby individual features or a combination of features of the illustrated embodiments can also be implemented independently of the remaining design of the respective embodiments in a proposed material shredder or in a shredding plant.

[0055] Fig. 1 shows a first embodiment of a

[0056] Crushing plant in cross-section (1a) with partial detailed views (1b and 1c),

[0057] Fig. 2 is a perspective view obliquely from above of a grinding device of the embodiment of Fig. 1,

[0058] Fig. 3 is a perspective detailed view of the grinding device from Fig. 2 from below,

[0059] Fig. 4 is a perspective detail view of the embodiment of Fig. 1,

[0060] Fig. 5 shows another embodiment of an open shredding plant in a perspective view obliquely from above,

[0061] Fig. 6 is a cross-section of the embodiment of Fig. 5, and

[0062] Fig. 7 shows a cross section of the embodiment from Fig. 5 in the closed state.

[0063] Fig. 1 shows a first embodiment of a shredding system 100 in cross-section, comprising a material shredder 1 and a feed device 2. Several rotor blades 14 are arranged on a rotor shaft 15, forming the rotor referred to as the cutting head 10, which is horizontally aligned and rotatably mounted and driven, for example, by an electric motor. The cutting head 10 is surrounded by a rotor housing referred to as the stator 20, with the cutting head 10 and the stator 20 defining a cutting chamber 3 arranged therebetween, in which the cutting material is shredded. The stator 20 has an inlet 21, into which the funnel-like feed device 2 opens, allowing the cutting material to be stirred into the cutting chamber 3.The stator 20 further has an outlet 22 in which a (perforated) screen 24, hereinafter referred to simply as screen 24, is arranged. This screen only allows sufficiently comminuted cuttings to pass through, which are sufficiently comminuted and thus pass through the screen. The cuttings emerging from the screen 24 enter a conveyor device 5, which conveys the comminuted cuttings for further processing (not shown in the drawing). An optionally openable inspection flap 7 provides access to the cutting chamber 3.

[0064] The cutting head 10 in Fig. 1a has a plurality of axially extending cutting blades 11 spaced apart from one another in the circumferential direction, with radially outer cutting edges 12 forming a cutting circumference. A plurality of counter blades 23 are arranged on the inner circumference of the stator 20. These counter blades protrude into the cutting chamber 3 and form a cutting gap 4 at a radial distance from the cutting blades 11 (Fig. 1b). With increasing wear of the cutting blades 11 at the cutting edge 12, or with increasing cutting edge radius, the cutting gap 4 increases (see also Fig. 1c).

[0065] Fig. 1b shows, in an enlarged detail, a grinding device 30, which has a carriage-like abrasive holder 31 and is arranged outside a cutting periphery of the cutting blades 11. The abrasive holder 31 is guided along a straight guide 32 (see also Figs. 2 and 4). A deflector wedge 6 prevents, in particular, bulky cutting material from accidentally jamming or wedging in the shredding system, thus reducing the risk of malfunction. By engaging the grinding pin 34 with the cutting edges 12, the cutting edge radius can be reduced.

[0066] The counterblade 23 is connected to a linear motor with an adjusting spindle 36 (Fig. 1c) for positional movement, allowing the counterblade 23 to be advanced largely automatically, depending on the material removal caused by grinding. Also visible, particularly in Fig. 1c, is a flap 37, which is open when grinding the cutting edges 12. In contrast, this flap can be optionally closed when no grinding process is planned, to seal an opening in the stator 20, thus preventing loss of the cut material.

[0067] The screen 24 in Fig. 1a is arranged in the outlet 22, wherein the screen 24 occupies a substantial portion of the circumference of the stator 20 surrounding the cutting head 10 and is fixed in a positionally movable manner in a screen holder 25. The screen holder 25 is pivotable via a pivot bearing 26, wherein the pivot axis is aligned in the axial direction of the cutting head 10 in order to be able to adjust the radial distance of the screen 24 from the cutting head 10 or from the cutting circumference.

[0068] Acting on the screen holder 25 in Fig. 1a, an adjusting device 40 is arranged with an adjustment pin 41, which, in particular by means of a rotary control, causes a radial adjustment of the screen 24 to the cutting circumference, such that the distance between the screen 24 and the cutting blade 11 or the cutting circumference is adjustable. Even with increasing material removal at the cutting edge 12 due to grinding, the distance between the cutting circumference and the screen 24, which is relevant for the cutting edge retention and the drive energy requirement, can thus be kept largely constant and optimized, for example, depending on the material being cut.

[0069] Fig. 2 shows a perspective view obliquely from above of a grinding device 30 of the exemplary embodiment from Fig. 1. An abrasive holder 31 is held in a carriage-like manner along a straight guide 32 so that the grinding pin 34 can be guided along the cutting edges 12. The abrasive holder has, among other things, a nozzle unit 35, with an application nozzle 35a arranged above the grinding pin 34 and a suction nozzle 35b arranged below the grinding pin 34. A cooling fluid is applied during grinding by means of the application nozzle 35a. The suction nozzle 35b serves to directly suction away the grinding dust in order to prevent contamination of the cut material.

[0070] Fig. 3 shows a perspective detailed view of the grinding device 30 from Fig. 2, viewed diagonally from below. The grinding pin 34 can be seen, which is held in an abrasive holder 33. A toothed ring 38 on the circumference of the abrasive holder 33 interacts with a spring tab 39 such that the abrasive holder 33 allows the grinding pin 34 to rotate exclusively in one direction and always by a radian measure in the form of a partial revolution, which corresponds to the length of a tooth root or a multiple thereof. Each partial revolution causes the grinding pin 34 to advance, i.e., brings the grinding pin 34 closer to the cutting circumference or to the cutting edges 12 of the cutting blades 11. The advance preferably takes place in the grinding zone with rotation of the cutting head 10, which effects the work grinding. A perspective detail view of the exemplary embodiment from Fig. 1 is shown in Fig. 4.The straight guide 32 is fixedly mounted and aligned parallel to the longitudinal extension of the cutting blades 11. In a pendulum motion, indicated in the drawing by a double arrow, the abrasive holder 31 is moved back and forth along the straight guide 32 and thus along the cutting blades 11 during the grinding process, while the grinding pin 34 engages the cutting edges 12.

[0071] Another exemplary embodiment of a particularly compact solution for a comminution system 100 is shown in Fig. 5 in a perspective view obliquely from above. In the present case, the comminution system 100 is shown in an open state, i.e., in particular, two sieves 24 are pivoted open and each exposes an outlet 22, whereby for illustrative reasons only one outlet 22 is visible (see also Fig. 6). In contrast to the first exemplary embodiment, the cutting head 10 is now oriented vertically. The cutting material is fed in from above via the feed device 2, parallel to the axis of rotation of the cutting head. A further difference is that not one, but two sieves 24 are provided, each of which is pivotably held in a sieve holder 25. The straight guide 32 of the grinding device 30 is aligned parallel to the axis of rotation of the cutting head 10.

[0072] Fig. 6 shows a cross-section of the exemplary embodiment from Fig. 5. The flap 37 is shown open so that grinding of the cutting edges 12 of the cutting blades 11 by means of a grinding pin 34 is possible. A feed cone 8 on the cutting head 10 ensures, among other things, that the cut material is guided outwards to the rotating cutting blades 11. The cutting blades 11 interact with the counter blades 23 and effect the comminution of the cut material. The exemplary embodiment from Figs. 5 and 6 is shown in cross-section in Fig. 7 in a closed state. In this case, the flap 37 is shown closed so that the grinding device 30 cannot be actuated in this configuration. Secondly, the sieves 24 are shown closing the outlets 22. Also visible are the cutting blades 11 of the cutting head 10, which, together with the counter blades 23, define the cutting gap 4.

[0073] A maintenance procedure is explained below by way of example, in particular for an application in which the cutting blades 11 exhibit advanced wear.

[0074] In this case, an abrasive is brought into engagement with a cutting circumference formed by a cutting edge 12 of a cutting blade 11 by advancing an abrasive to a cutting blade 11, i.e. the radial distance between the abrasive and the grinding edge 12 is reduced until the abrasive is in contact with the grinding edge 12. The extent of material removal on the cutting blade 11 is defined depending on a further advance of the abrasive after the first contact between the abrasive and the cutting edge 12.

[0075] Beginning before or even during the feed, the abrasive is guided along a cutting blade 11, which is arranged axially extending on the cutting head 10, wherein the cutting edge 12 is preferably ground several times over the entire length of the cutting blade 11 and in a pendulum motion. It is important that the rotatably mounted cutting head 10 rotates. The abrasive is preferably held on the cross-sectional surface of a cup wheel, wherein the cup wheel also rotates, during which the abrasive is guided back and forth along the cutting edge 12 in a pendulum motion. Within the scope of the exemplary maintenance method, a sieve 24, which is arranged in an outlet 22 of the stator 20, is also fed radially by reducing the radial distance between the sieve 24 and a cutting blade 11.

[0076] After grinding the cutting blade 11 or even during this process, the counter blades 23, which are arranged on the inner circumference of the stator 20, are advanced by reducing the radial distance between the cutting blade 11 and the counter blade 23, so that a specific distance, referred to as the cutting gap 4, is set. If a counter blade 23 also shows advanced wear, the counter blade 23 is also ground before the advance. The work steps of the maintenance process are regulated by a control unit, so that optimized and largely automated maintenance can be carried out.

[0077] Reference symbol:

[0078] Material shredder feeding device cutting chamber

[0079] Cutting gap

[0080] Conveyor device deflector wedge

[0081] Inspection flap feed cone

[0082] Cutting head

[0083] Cutting knife

[0084] cutting edge

[0085] rotor blade

[0086] rotor shaft

[0087] stator

[0088] inlet

[0089] Outlet

[0090] Counter knife

[0091] Sieve

[0092] sieve holder

[0093] Swivel bearing Grinding device Abrasive holder Straight guide Abrasive holder

[0094] Grinding pin nozzle unit a Application nozzle b Suction nozzle

[0095] Linear motor with adjusting spindle flap

[0096] Gear ring Spring tab Adjustment device Feed pin 0 Crushing system

Claims

Claims: 1 . Material shredder (1), in particular for shredding recyclable cuttings, with a rotatably mounted rotor, referred to as cutting head (10), on which a plurality of axially extending cutting blades (11) are arranged, spaced apart from one another in the circumferential direction, which have radially outer cutting edges (12) forming a cutting circumference, with a rotor housing, referred to as stator (20), which substantially surrounds the cutting head (10), wherein the stator (20) and cutting head (10) delimit a cutting chamber (3) arranged therebetween, into which the cutting blades (11) and at least one counter-blade (23) arranged on the inner circumference of the stator (20) project, wherein the counter-blade (23) is arranged radially spaced from the cutting circumference to form a cutting gap (4), and wherein the stator (20) has at least one outlet (22) in which a sieve (24) is arranged, characterized in thatthat the material shredder (1) has a grinding device (30) with an abrasive holder (31) holding an abrasive, wherein the grinding device (30) is arranged outside the cutting circumference, and that the abrasive and the sieve (24) are positionally movable such that the respective radial distance from the cutting circumference is selectively adjustable.

2. Material shredder (1) according to claim 1, characterized in that that the grinding device (30) has a straight guide (32) and the abrasive holder (31) is arranged displaceably on the straight guide (32) along the cutting blades (11).

3. Material shredder (1) according to claim 1 or 2, characterized in that the abrasive means holder (31) has an abrasive means holder (33) which holds the abrasive means in a rotationally movable manner, in such a way that the abrasive means is rotatable about an axis of rotation which is aligned substantially perpendicular to the axis of rotation of the cutting head (10).

4. Material shredder (1) according to one of the preceding claims, characterized in that the grinding device (30) has an abrasive feed which is intended to selectively adjust the radial distance of the abrasive to the cutting head (10).

5. Material shredder (1) according to one of the preceding claims, characterized in that the grinding device (30) has a nozzle unit (35), wherein at least one suction nozzle (35b) is oriented in a suction-effective manner and / or an application nozzle (35a) is oriented in an application-effective manner to the cutting circumference.

6. Material shredder (1) according to one of the preceding claims, characterized in that the screen (24) is held pivotably coaxially to the rotational axis of the cutting head (10), and that an adjusting device (40) is arranged outside the cutting chamber (3), which adjusts the screen (24) acts in such a way that the radial distance of the sieve (24) to the cutting head (10) and thus the size of the cutting chamber (3) can be optionally adjusted.

7. Material shredder (1) according to one of the preceding claims, characterized in that the screen (24) has a material thickness which decreases in cross-section at one end in an edge region of the screen (24) referred to as the transition zone, and in that the stator (20) and screen (24) are arranged overlapping one another in the transition zone, the screen (24) being arranged radially inward.

8. Material shredder (1) according to one of the preceding claims, characterized by a control unit which is connected to the grinding device (30) for signal transmission.

9. Material shredder (1) according to one of the preceding claims, characterized in that a guide element projecting radially inwards into the cutting chamber (3) is arranged on the stator (20) outside the cutting circumference.

10. Material shredder (1) according to one of the preceding claims, characterized by an optical cuttings detection device which detects the cuttings after they have exited the cutting chamber (3).

11. Material shredder (1) according to one of the preceding claims, characterized by an acoustic sensor which detects the structure-borne sound vibrations caused when a cutting blade (11) passes a counter-blade (23), the structure-borne sound vibrations serving to determine the wear of the cutting blades (11).

12. Material shredder (1) according to one of the preceding claims, characterized in that a counter knife (23) is releasably fixed in a knife holder arranged on the stator (20), wherein the knife holder is movable relative to the cutting head (10) in such a way that the counter knives (23) can be continuously approached to the cutting circumference.

13. Material shredder (1) according to one of the preceding claims, characterized in that a knife holder arranged on the stator (20) has knife seats for a plurality of counter knives (23), and that the knife holder is mounted so as to be rotatable.

14. Material shredder (1) according to one of the preceding claims, characterized by a suction device which acts on the cutting chamber (3) through the outlet (22) in a suction-flow-effective manner.

15. Shredding plant (100), in particular for shredding recyclable cuttings, with a shredding device, and with a feeding device (2) which is intended to feed cuttings to the shredding device, characterized in that the shredding device is a material shredder (1) according to one of the preceding claims.

16. Shredding plant (100) according to claim 15, characterized by a dosing device which opens into the feed device (2) and is intended to introduce a dosed quantity of cuttings into the cutting chamber (3).

17. Comminution plant (100) according to claim 15 or 16, characterized by a conveying device forming a conveying path, wherein the conveying path opens into the feeding device (2) and / or the dosing device.

18. Maintenance method for a material shredder (1) comprising the following method steps: a) Radial feeding of an abrasive to a cutting blade (11) which is arranged on a rotatably mounted rotor of a material shredder (1), referred to as a cutting head (10), such that the abrasive is brought into grinding engagement with a cutting edge (12) of the cutting blade (11); b) Grinding-effective guidance of the abrasive along the cutting blade (11), the cutting head (10) rotating during this time; c) Radial feeding of a screen (24) which is arranged in an outlet (22) of the stator (20) such that the radial distance of the screen (24) to a Cutting blade (11) is reduced. Maintenance method according to claim 18, characterized by d) a radial advance of a counter-blade (23), which is arranged on a rotor housing surrounding the cutting head (10) and referred to as a stator (20), such that the radial distance between the cutting blade (11) and the counter-blade (23) is reduced. Maintenance method according to claim 18 or 19, characterized in that the method steps are regulated by a control unit. Maintenance method according to one of claims 18 to 20, characterized in that the counter-blade (23) is ground before advancement.

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