Roll crusher and operation method thereof

Abstract

A roll crusher and a method of operating the same. A roll crusher having two substantially parallel rolls arranged to rotate in opposite directions and separated by a gap wherein at least one roll has a flange at its end, the roll crusher further comprising a material removal device, the material removal device comprising: a rotatable cutting unit having a plurality of cutting elements, the cutting elements are tangentially arranged around the rotatable cutting unit at respective radial distances from the axis of rotation of the rotatable cutting unit; and a rotating device arranged to rotate the rotatable cutting unit, the rotatable cutting unit being arranged at one end of the flanged roller such that, when the rotating device rotates it, material accumulated on the envelope surface at the end portion of the roller adjacent the flange and / or on the flange is at least partially permitted to be cut off. The cutting elements each have an impact surface arranged to face the material to be cut, and each impact surface comprises polycrystalline diamond (PCD).

Description

Technical Field

[0001] The present disclosure relates to a roller crusher having two substantially parallel rollers, wherein the roller crusher comprises a flange attached to at least one end of one of the rollers. The present disclosure also relates to a method of operating a roller crusher. Background Art

[0002] When crushing or grinding rocks, ores, cement clinker and other hard materials, a roller crusher can be used, which has two roughly parallel rollers that rotate in opposite directions toward each other and are separated by a gap. The material to be crushed is then fed into the gap. A roller crusher is called a high-pressure grinding roller or a high-pressure roller crusher. This type of comminution has been described in US4357287, in which it has been determined that when trying to achieve fine and / or very fine comminution of materials, it is actually not necessary to strive for individual particle breakage. On the contrary, it has been found that by introducing sufficiently high compression forces so that briquetting or agglomeration of particles occurs during comminution, significant energy savings and increased production can be achieved. This crushing technology is called intergranular crushing. Here, the material to be crushed or shredded is not only crushed by the crushing surface of the roller, but also by the particles in the material to be crushed, and is therefore named intergranular crushing. US4357287 points out that this "agglomeration" can be achieved by using higher compression forces than before. For example, previously, the maximum used was 200 kg / cm 2 The solution in US4357287 suggests using at least 500kg / cm 2 And up to 1500kg / cm 2 In a roller crusher with a roller diameter of 1 meter, 1500kg / cm 2 This translates into forces greater than 200,000 kg per meter of roller length, whereas previously known solutions could and only could achieve a fraction of these forces. Another characteristic of inter-particle crushing is that the roller crusher should be fed with the material to be crushed in a choke feed, which means that the gap between the two opposing rollers of the roller crusher should always be filled with material along its entire length, and there should also always be material filled to a certain height above the gap to always keep the gap full and maintain a state of particle-to-particle compression. This will increase the yield and reduce it to finer materials. This is in sharp contradiction with earlier solutions, which always emphasized that single particle rupture was the only way to obtain fine and very fine particle comminution.

[0003] In contrast to some other types of crushing equipment (e.g. screens), inter-particle crushing has the characteristic that it does not produce a series of shocks and widely varying pressures during use. Instead, equipment using inter-particle crushing works with very high, almost constant pressure on the material in the gap between the rollers and in the crushing zone formed around the gap.

[0004] In order to maintain the crushing effect along the entire length of the grinding roller, flanges can be arranged at the ends of the crushing rollers; one flange is arranged at each end of one roller, or one flange is arranged at one end of each roller, but located on opposite ends of the roller crusher. With this arrangement, a more efficient and uniform roller feed inlet can be produced. The flanges will allow such a feed that a preferred material pressure is generated over the entire length of the crushing roller. It has been shown that the production capacity of a given roller crusher can be increased by up to 20%, and sometimes even more, by using flanges. A general problem associated with grinding rollers without flanges is that the ratio between the roller diameter and the roller width is very important due to the significant edge effect (i.e., the crushing result at the edge of the roller is reduced). This is because the material may overflow from the edge of the roller, thereby reducing the crushing pressure on the material towards the gap at the edge of the roller. Therefore, in the absence of flanges, it is necessary to recover the material escaping from the roller and some of the material that has passed through the gap at the edge of the crushing roller due to reduced rupture caused by the lower pressure at the edge.

[0005] However, during operation of a grinding mill having flanges, the flanges and the edges of the opposing crushing rollers are subject to significant stress and wear, and build-up material will accumulate at the transition between the crushing roller surface and the flanges. This excess build-up material needs to be continuously removed during operation of the grinding mill.

[0006] The prior art has proposed a scraper element for removing accumulated material in the transition between the crushing roller surface and the flange, see for example AU2018264756 or US5054701.

[0007] Starting from this, it is an object of the present disclosure to provide a roller crusher with a flange, wherein the flange and the edges of the opposite roller crusher ends are subject to less stress and wear. Summary of the invention

[0008] According to a first aspect of the present disclosure, this object and other objects are fully or at least partially achieved by a roller crusher having two substantially parallel rollers arranged to rotate in opposite directions and separated by a gap, each roller having two ends, the roller crusher comprising:

[0009] a flange, attached to one end of one of the rollers,

[0010] The flange extends in the radial direction of the roller, and

[0011] The flange has an extension (H) beyond the envelope surface of the roller,

[0012] The roller crusher further comprises a material removal device, which comprises:

[0013] a rotatable cutter unit having a plurality of cutting elements arranged tangentially around the rotatable cutter unit at respective radial distances from an axis of rotation of the rotatable cutter unit; and

[0014] a rotating device arranged to enable the rotary cutting unit to rotate,

[0015] wherein a rotatable cutting unit is arranged at one end of a roller with a flange so as to at least partially allow the material accumulated on the envelope surface of the roller at the end portion adjacent to the flange and / or on the flange to be cut off when the rotating device rotates it,

[0016] wherein each of the plurality of cutting elements has an impact surface arranged to face the material to be removed, and

[0017] Each of the impact surfaces comprises polycrystalline diamond (PCD).

[0018] The term "impact surface" refers herein to a surface of a cutting element that at least partially faces the tangential direction of motion defined at the impact surface and is oriented along the direction of rotation of the rotatable cutting unit. In other words, the impact surface has a projection on a plane orthogonal to the tangential direction of motion, which projection is greater than zero. As will be readily appreciated by those skilled in the art, this achieves the effect that, when the material removal device is arranged on a roll crusher, the impact surface can be arranged so that it at least partially faces the material to be removed. The impact surface may include one or more sub-surfaces, referred to herein as "portions". These can be shaped in different ways so as to meet the above-mentioned criteria of non-zero projection to varying degrees. However, all surfaces facing the material to be removed in one way or another will form part of the impact surface. Surfaces that do not meet the above criteria may still be subject to wear, but are of an abrasive nature rather than impact driven. Therefore, these abrasive surfaces are not referred to herein as impact surfaces. This can be expressed in another way: each cutting element may have one or more wear surfaces, wherein the one or more wear surfaces include an impact surface arranged to face the material to be removed and optionally one or more abrasive surfaces.

[0019] The first advantage of having an impact surface comprising polycrystalline diamond (PCD) is that the wear life of the cutting element is significantly extended. Typically, such an impact surface will include a wear-resistant material such as ceramic or a composite material containing tungsten carbide, titanium carbide or vanadium carbide, but using an impact surface comprising polycrystalline diamond (PCD), the wear life can be extended by up to about 50 times compared to a composite material comprising, for example, tungsten carbide alone.

[0020] It is conceivable to provide other surfaces of the cutting element with polycrystalline diamond (PCD). For example, a side surface of the cutting element that does not form part of the impact surface and can therefore be considered an abrasive surface may include polycrystalline diamond (PCD). Such side surfaces of the cutting element may include, for example, a surface of the cutting element facing the flange, a surface of the cutting element facing away from the flange, and a surface of the cutting element facing the roller surface. Therefore, it should be understood that the concepts of the present disclosure should not be interpreted as being limited to only the impact surface of the cutting element (i.e., its forward-facing surface) including polycrystalline diamond (PCD).

[0021] According to one embodiment, the cutting element further comprises a wear resistant material in which polycrystalline diamond (PCD) is at least partially embedded.

[0022] In an alternative embodiment, polycrystalline diamond (PCD) may be attached to the surface of the wear resistant material of the cutting element.

[0023] Wear-resistant materials may include ceramic materials such as titanium carbide, vanadium carbide or tungsten carbide; metal-ceramic composites such as cemented carbides (cemented carbides), such as titanium carbide, tungsten carbide or vanadium carbide, with cobalt as a binder; or metal matrix composites including titanium carbide, tungsten carbide or vanadium carbide.

[0024] In one embodiment, the wear resistant material is a cemented carbide including tungsten carbide and cobalt as a binder, wherein the binder content may be 10-15 weight percent (wt %).

[0025] In one embodiment, polycrystalline diamond (PCD) is embedded in tungsten carbide, vanadium carbide, or titanium carbide.

[0026] According to one embodiment, the impact surface of the cutting element may include a layer of polycrystalline diamond (PCD).The layer of polycrystalline diamond (PCD) may have a thickness of 0.4 to 3.2 mm, or 1.0 to 2.0 mm, or 1.35 to 1.8 mm, or 1.4 to 1.6 mm, or about 1.5 mm.

[0027] According to one embodiment, the impact surface of the cutting element may include two or more layers of polycrystalline diamond (PCD). Other surfaces of the cutting element (e.g., abrasive surfaces or wear surfaces) may also include two or more layers of polycrystalline diamond (PCD). The two or more layers may be attached to each other, for example, by an adhesive. The number of layers and / or the thickness of each layer may depend on the particle size and / or its application.

[0028] The diamond grain size of the polycrystalline diamond (PCD) of the impact surface may be 0.8 to 30 μm, which is determined by image analysis using a scanning electron microscope (SEM).

[0029] The particle size of the diamond can be measured by various measurement techniques such as a laser particle size analyzer or a scanning electron microscope (SEM). An example of a laser particle size analyzer is a Malvern particle size analyzer device based on laser diffraction. The value determined using the laser particle size analyzer can be the initial diamond particle size, which for some embodiments can then be subjected to high pressure and high temperature sintering. When the diamond particles have been sintered and compacted to form a polycrystalline diamond (PCD) that impacts the surface, image analysis by means of a scanning electron microscope is used to determine the final microstructure particle size distribution, i.e., the diamond particle size of the polycrystalline diamond (PCD) that impacts the surface.

[0030] The roller crusher of the first aspect may be advantageous because it allows the removal of accumulated material on the envelope surface at the end portion of the roller adjacent to the flange and / or on the flange in a more efficient manner. The rotatable cutting unit may be considered as a plurality of movable impact surfaces, each of which is defined on a respective one of the plurality of cutting elements. During operation, material is removed due to the impact forces generated between the material build-up on the roller and these impact surfaces. The impact force will increase with the increase in the relative speed between the speed of the material build-up (i.e. determined by the tangential speed of the envelope surface, which is also referred to herein as the roller surface or outer surface of the roller with flanges) and the speed of the impact surface (i.e. determined by the tangential speed of the cutting elements on the rotatable cutting unit). By providing a rotatable cutting unit, material removal does not rely solely on the impact forces generated by the movement of the roller relative to the material removal device (as is the case when the material removal device is a fixed scraper and thus defines a fixed impact surface). Instead, by rotating the rotatable cutting unit, the impact surface of the rotatable cutting unit can acquire a considerable tangential speed on its own. If the rotatable cutting unit is caused to rotate in the same direction of rotation as the flanged roller, the impact force will increase significantly, allowing more efficient and reliable material removal. Another advantage of the rotatable cutting unit is that it allows the impact force to be adjusted for specific situations. For example, there may be situations where it is less desirable to have high impact forces. For this case, the rotation speed of the rotatable cutting unit can be reduced during material removal to reduce the impact force without affecting the operation of the crusher itself (i.e., the rotation speed of the flanged roller can be kept constant). Even in some cases, it is desirable to reduce the impact force to a degree that exceeds that which can be achieved with a fixed scraper. For this case, the rotatable cutting unit can be rotated in a direction of rotation opposite to the direction of rotation of the flanged roller. Another advantage of the rotatable cutting unit is that providing multiple cutting elements increases the overall wear resistance of the material removal device compared to a fixed scraper. Multiple cutting elements will share the wear, whereby a single cutting element will have a longer life expectancy. This allows an increase in the operating time period before maintenance of the material removal device, thereby reducing the downtime of the roller crusher.

[0031] It will be readily understood by those skilled in the art that the rotatable cutting unit can rotate about a cutting unit rotation axis. The cutting unit rotation axis is preferably parallel to the rotation axis of the flanged roller. However, it is conceivable that the cutting unit rotation axis is angled relative to the rotation axis of the flanged roller, which will be described in more detail below.

[0032] The rotatable cutting unit may be arranged such that the cutting unit rotation axis forms an inclination angle φ relative to the rotation axis of the roller in a radial plane of the roller, the radial plane of the roller intersecting the cutting unit rotation axis. This means that the rotatable cutting unit will not be parallel to the flange of the roller, resulting in a change in the distance between the rotatable cutting unit and the flange in the radial direction of the roller. The inclination angle φ may be in the range of 0 to 90 degrees, preferably in the range of 0 to 45 degrees.

[0033] Alternatively or additionally, the rotatable cutting unit may be arranged such that the cutting unit rotation axis forms an offset angle with respect to the rotation axis of the roller in a tangential plane of the roller. The tangential plane is orthogonal to the radial plane of the roller, which intersects the axis of rotation of the cutting unit. This means that the rotatable cutting unit will not be parallel to the flange of the roller, resulting in a variation in the distance between the rotatable cutting unit and the flange in the tangential direction of the roller surface. It can be in the range of 0 to 20 degrees, preferably in the range of 0 to 15 degrees. Preferably, the deflection angle The distance between the rotatable cutting unit and the flange is defined so that it is at a minimum at the upstream end of the material removal device. This may be advantageous because since the distance between the rotatable cutting unit and the flange is wider at the downstream end of the material removal device, this may help to remove broken up accumulated material at the downstream end of the material removal device.

[0034] The rotatable cutting unit can rotate in the same direction of rotation as the roller with the flange. Alternatively, the rotatable cutting unit can rotate in the opposite direction of rotation to the roller with the flange. The rotation speed of the rotatable cutting unit can be in the range of 1rpm to 200rpm. As those skilled in the art will readily appreciate, an important factor is the relative difference in tangential velocity between the roller surface and the cutting element of the rotatable cutting unit at the impact point between the two. If the rotatable cutting unit rotates in the same direction of rotation as the roller with the flange, the maximum relative difference in tangential velocity will usually be obtained. If the rotatable cutting unit rotates in the opposite direction of rotation to the roller with the flange, the relative difference in tangential velocity will be smaller. At a specific ratio between the rotation speed of the roller and the rotation speed of the rotatable cutting unit, the relative difference in tangential velocity will be zero, which will result in a loss of cutting action. Therefore, when operating the rotatable cutting unit in the opposite direction of rotation to the roller, this operating situation must be carefully avoided. For an efficient cutting operation, the relative tangential speed is preferably higher than 1.25 times the tangential speed of the roller surface.

[0035] The rotatable cutting unit can be mounted on or attached to a rotating shaft. The rotating shaft can be a through rotating shaft. This means that the rotating shaft extends through the rotatable cutting unit. This can be advantageous because it allows the rotating shaft to be supported at both ends of the rotatable cutting unit, thereby providing improved structural integrity. However, it is conceivable that the rotatable cutting unit is mounted on or attached to a non-through rotating shaft. This may have the advantage of making it easier to replace the rotatable cutting unit.

[0036] The rotatable cutting unit has a plurality of cutting elements, which are arranged tangentially around the rotatable cutting unit. This means that the cutting elements are arranged along the periphery of the rotatable cutting unit. In other words, each cutting element will be arranged on a circular path. This also means that the cutting elements are arranged radially away from the axis of rotation of the cutting unit. Preferably, the cutting elements are arranged at the same radial distance from the axis of rotation of the cutting unit. However, it is conceivable that the cutting elements are arranged at different radial distances from the axis of rotation of the cutting unit. For example, every other cutting element can be arranged at a first radial distance from the axis of rotation of the cutting unit, while the remaining cutting elements are arranged at a second radial distance from the axis of rotation of the cutting unit, wherein the first radial distance and the second radial distance are different. This allows a material removal device to be provided, which can also improve the material removal efficiency after reaching a certain degree of wear. The cutting elements can be arranged tangentially around the rotatable cutting unit at equal distances from each other. This means that for all cutting elements, the distance between a cutting element and its adjacent cutting element is the same. However, it is also conceivable that the cutting elements are arranged at different distances from each other.

[0037] The rotatable cutting unit can be formed integrally from a single element. This means that a plurality of cutting elements will form radially extending protrusions on such a single element. Alternatively, the rotatable cutting unit can be an assembly of two or more elements. This will be further described below and will define exemplary embodiments.

[0038] Each cutting element of the plurality of cutting elements has an impact surface which is arranged to face the material to be removed. The term "impact surface" should be interpreted as any surface of the cutting element which first comes into contact with the material accumulated on the envelope surface at the end portion of the roller adjacent to the flange and / or on the flange. This means that the impact surface faces the material to be removed.

[0039] According to one embodiment, the impact surface is substantially flat and arranged transversely to the tangential movement direction of the cutting element.This exemplary embodiment is similar to the geometry of prior art fixed scrapers and due to its inherent simplicity may be easier and cheaper to manufacture.

[0040] According to one embodiment, the rotatable cutting unit is arranged such that a plurality of cutting elements passes during operation at a distance from the outer surface at the end of the roller and / or from the flange.

[0041] Alternatively, the distance between the cutting element and the roller surface and / or the flange can be defined using a minimum roller distance and a minimum flange distance, respectively. The minimum roller distance is defined as the minimum distance between the cutting element and the envelope surface of the roller. Similarly, the minimum flange distance is defined as the minimum distance between the cutting element and the inner surface of the flange.

[0042] According to one embodiment, the rotatable cutting unit is arranged at a first end of the material removal device and the rotating device is arranged at an opposite second end of the material removal device, and wherein the rotatable cutting unit extends in a reference plane orthogonal to the rotation axis.

[0043] According to one embodiment, each impact surface of the plurality of cutting elements is substantially flat and is arranged to be inclined relative to a normal to a reference plane defined in front of the impact surface, and the inclination is such that the distance between the normal and the impact surface decreases toward the flange. The normal is defined as a straight line orthogonal to the reference plane. When the material removal device is arranged in a non-inclined manner relative to the roller, the reference plane will be parallel to the plane defined by the inner surface of the flange. For this configuration, the normal is also orthogonal to the inner surface of the flange. However, as will be described later herein, the roller crusher of the present disclosure is not limited to this arrangement, and inclined configurations in which the reference plane of the rotating cutting unit and the plane defined by the inner surface of the flange are not parallel to each other are also conceivable.

[0044] The advantage of the impact surface being inclined relative to the normal to the reference plane and decreasing in distance towards the flange is that material removed from a location in the corner formed by the envelope surface of the roll and the inner surface of the flange will be pushed towards the center of the roll by the inclined impact surface, rather than being squeezed and compacted between the cutting elements and the inner surface of the flange. The term "inner surface" refers to the surface of the flange facing the center of the roll. Therefore, the inner surface of the flange will be in contact with the material to be crushed.

[0045] According to one embodiment, the impact surface may be substantially flat. Thus, according to this embodiment, the varying distance as above may be further represented by an angle α defined between the impact surface and the normal to the reference plane, wherein the angle α is defined in a tangential plane of the cutting element orthogonal to the reference plane. The angle α may be 1° to 45°, 1° to 35°, 1° to 30°, 1° to 15°, or 2° to 10°, or 3° to 8°, or 4° to 6°, or 5°.

[0046] A "tangential plane of a cutting element" is herein a plane parallel to the tangential direction of motion of the cutting element, as defined at the impact surface and pointing in the direction of rotation of the rotatable cutting unit, and which plane is orthogonal to the reference plane. Thus, each of the plurality of cutting elements has an associated tangential plane, which are angled relative to each other as the cutting elements are arranged tangentially around the rotatable cutting unit.

[0047] According to one embodiment, the impact surface has a front part and a rear part interconnected to each other, wherein the front part is arranged upstream of the rear part with respect to the tangential movement direction of the cutting element, and wherein the front part is arranged closer to the flange than the rear part. This can be advantageous because it allows to generate very strong impact forces by the front part on a local area of ​​the accumulated material on the roller with the flange, thereby increasing the probability of breaking off a larger part of the material. The rear part can then intervene and help to remove further material from the roller and / or convey the already removed material away from the flange area.

[0048] According to one embodiment, the rear portion is shaped to convey the cut material in a direction away from the flange. This means that the rear portion is shaped to achieve a turboprop effect.

[0049] According to one embodiment, the rear portion is substantially flat and forms an oblique angle with respect to the tangential movement direction of the cutting element. This may be advantageous because it is relatively easy and cheap to manufacture.

[0050] According to one embodiment, the rear portion is curved inwardly to form a bowl shape, also referred to as a concave shape. The bowl shape may further enhance the propeller effect and thus further enhance the conveying of the removed / loosened material from the flange area.

[0051] According to one embodiment, each cutting element has a surface facing the flange, which has an extension (extension) from its impact surface tangentially towards its rear end, wherein the cutting element is constructed and arranged so that the distance between the surface facing the flange and the rotating device decreases towards the impact surface over at least a portion of the extension. The expression "the surface has an extension from its impact surface tangentially towards its rear end" means that the cutting element has an extension on its back side. The surface facing the flange will therefore be located downstream of the impact surface. Therefore, the expression "extension tangentially..." should be interpreted broadly and be read as including any surface having an extension or dimension substantially parallel to the tangential direction of movement at the position of the cutting element. This extension does not have to be the main extension of the cutting element.

[0052] An advantage of a cutting element having such a structure and arrangement is that material removed from a location in the corner formed by the outer surface of the roller and the inner surface of the flange will tend to flow along the surface of the cutting element facing the flange, and as the distance away from and downstream of the impact surface increases, the removed material will be allowed to be removed toward the center of the roller rather than being squeezed and compacted between the cutting element and the inner surface of the flange.

[0053] According to one embodiment, the surface facing the flange is substantially flat. Therefore, according to this embodiment, the varying distance as described above can be further represented by an angle β defined between the surface facing the flange and the reference plane, wherein the angle β is defined in a tangential plane of the cutting element orthogonal to the reference plane. The angle β can be 1° to 45°, 1° to 40°, 1° to 30°, 5° to 25°, or 5° to 20°, or 5° to 15°, or 8° to 12°, or 10°.

[0054] According to one embodiment, each cutting element has a surface facing the flange, which surface includes polycrystalline diamond (PCD). Similar to the polycrystalline diamond (PCD) on the impact surface, on this surface facing the flange, the polycrystalline diamond (PCD) can also be at least partially embedded in the wear-resistant material, as described above.

[0055] According to one embodiment, each of the plurality of cutting elements has a surface facing away from the flange, which surface has an extension tangentially from the impact surface toward its rear end, wherein the cutting elements are constructed and arranged so that the distance between the surface facing away from the flange and the rotating device decreases toward the impact surface over at least a portion of the extension. On at least one cutting element, the surface facing away from the flange is opposite to the surface facing the flange. As will be readily appreciated by a person skilled in the art, the distance defined between the surface facing away from the flange and the rotating actuator must inevitably be defined as passing through the cutting element having said surface. In the context of defining a distance, "surface" should be understood as a mathematical or geometric surface. Likewise, it is beneficial that the cutting element provides a surface that will cause the removed material to move toward the center of the roller.

[0056] According to one embodiment, the surface facing away from the flange comprises a substantially flat surface. Therefore, for this embodiment, the distance varied as described above can be further expressed as an angle γ defined between the surface facing away from the flange and the reference plane, wherein the angle γ is defined in a tangential plane of the cutting element orthogonal to the reference plane. The angle γ can be 1° to 45°, or 1° to 40°, or 1° to 30°, or 5° to 25°, or 5° to 20°, or 5° to 15°, or 8° to 12°, or 10°. Although preferably angled so that the distance between the surface facing away from the flange and the rotating device decreases toward the impact surface over at least a portion of the extension, it is also conceivable to provide a cutting element having a surface facing away from the flange, the cutting element being arranged so that the distance between the surface facing away from the flange and the rotating device increases toward the impact surface over at least a portion of the extension. As will be readily appreciated by those skilled in the art, for substantially flat surfaces, this will be defined using the negative angle γ defined using the above definition. For such an embodiment, the angle γ can therefore be -1° to -45°, or -1° to -40°, or -1° to -30°, or -5° to -25°, or -5° to -20°, or -5° to -15°, or -8° to -12°, or -10°.

[0057] According to one embodiment, the plurality of cutting elements are arranged to form an axial protrusion on one or both sides of the rotatable cutting unit. In other words, the plurality of cutting elements are arranged so that they protrude axially beyond one or both axial ends of the remainder of the rotatable cutting unit. Therefore, when the rotatable cutting unit is arranged in a roller crusher for operation and the plurality of cutting elements have an axial extension toward the flange, the distance between the plurality of cutting elements and the flange is narrower than the distance between the remainder of the rotatable cutting unit and the flange. One advantage of this is that, in the case where the rotatable cutting unit is arranged and operated in a roller crusher, once the removed material flows along the surface of the cutting unit facing the flange, the material will be easily removed through the wider gap between the inner surface of the flange and the remainder of the rotatable cutting unit and flow toward the center of the roller, rather than being squeezed and compacted between the rotatable cutting unit and the inner surface of the flange.

[0058] According to one embodiment, the axial protrusion has an axial extension in the range of at most 75 mm, or 5 to 50 mm, or 10 to 40 mm. Although the ranges disclosed above are currently preferred, it is conceivable that the axial extension may also be greater than 75 mm. The axial extension may depend on the roller crusher, the operating conditions and the material to be crushed, among other things. Therefore, the axial extension must be selected based on parameters such as, but not limited to, the crushing gap, the size of the crushing rollers and the size of the built-up material to be removed. Larger material build-ups may require larger axial extensions.

[0059] According to one embodiment, the rotatable cutting unit extends in a reference plane orthogonal to the rotation axis of the rotatable cutting unit, wherein each of the plurality of cutting elements extends in the reference plane along the cutting element axis towards the impact surface, and wherein the cutting element axis forms a first acute angle with a radial axis of the rotatable cutting unit along the reference rotation direction, the radial axis intersecting the cutting element. An advantage of this is that during operation, impact forces acting on the impact surface will become substantially aligned with the cutting element axis and are more likely to be absorbed in the direction of the cutting element axis, which is well supported and attached by the rotatable cutting unit.

[0060] According to one embodiment, each impact surface of the plurality of cutting elements extends in a plane having a normal that forms an acute angle with the cutting element axis along a reference direction. Again, an advantage of this is that during operation, impact forces acting on the impact surface become substantially more aligned with the cutting element axis and are more likely to be absorbed in the direction of the cutting element axis, which is well supported and attached by the rotatable cutting unit.

[0061] According to one embodiment, each of the plurality of cutting elements has a surface facing away from the flange and a surface facing the flange, and at least one of the surface facing away from the flange and the surface facing the flange comprises a ceramic insert. Arranging ceramic inserts on these surfaces will extend the wear life of the cutting elements.

[0062] According to one embodiment, each cutting element of the plurality of cutting elements comprises a cutting element retaining structure and an active cutting element attached thereto, wherein the active cutting element has the impact surface. This can be advantageous because it allows the use of dedicated cutting elements, which can thus be tailored specifically for cutting. Another advantage is that the active cutting element can be replaced when worn without having to replace the cutting element retaining structure, which can therefore be reused. This can reduce overall waste and costs.

[0063] According to one embodiment, the rotatable cutting unit has an annular engagement portion, and wherein each of the plurality of cutting elements can be releasably arranged to the annular engagement portion. The term "annular engagement portion" should be interpreted as an annular portion of a structure, which can consist of one element or of an assembly of a plurality of elements, which forms an outer periphery on which the plurality of cutting elements can be releasably arranged. The annular engagement portion can, for example, be a peripheral annular portion of a rotatable disc. Providing releasable cutting elements can be advantageous because it allows selective replacement of individual cutting elements. Thus, for example, if one cutting element is damaged, the remaining cutting elements can remain stationary and only the damaged element can be replaced.

[0064] According to one embodiment, the rotatable cutting unit further comprises a main support structure and at least two cutting element support structures, wherein the at least two cutting element support structures are releasably arranged relative to the main support structure and are shaped as a circular ring sector (circular ring portion) that together form a circular ring, and the circular ring has an annular engagement portion. In principle, the rotatable cutting unit can include any number of cutting element support structures. Therefore, it is also conceivable to provide a single cutting element support structure. However, the advantage of providing at least two cutting element support structures is that it allows installation on the main support structure, which is rotatably arranged on the through-axis. At least two cutting element support structures can have the same size. Therefore, for an embodiment with two cutting element support structures, each cutting element support structure can constitute a 180-degree circular ring sector. Alternatively, for an embodiment with three cutting element support structures, each cutting element support structure can constitute a 120-degree circular ring sector. Alternatively, for an embodiment with four cutting element support structures, each cutting element support structure can constitute a 90-degree circular ring sector. It is also conceivable that two or more cutting element support structures have different sizes. However, each embodiment has one thing in common: the at least two cutting element support structures will together form a ring, and the ring will have an annular joint portion. These exemplary embodiments may be advantageous because they provide modularity of the design, thereby facilitating easier and faster maintenance. By providing at least two cutting element support structures, a complete module including several cutting elements may be removed from the material removal device in a single operation. This may also increase speed and reliability when replacing cutting elements on the material removal device, as each cutting element may be replaced by replacing only the at least two cutting element support structures.

[0065] According to one embodiment, the plurality of cutting elements are each releasably arranged in the annular engagement portion by means of a geometric locking engagement. This can be advantageous because it allows the structure to be made impact resistant. During operation, the cutting elements will repeatedly impact the deposited material on the flanged roller, which will generate a torsional load in the connection area between the cutting elements and the annular engagement portion. By providing a locking engagement, this load can be at least partially absorbed by the structure itself, thereby reducing the load on the fasteners (e.g., bolts, screws and nuts) that are typically used to provide the releasable arrangement of the cutting elements to the annular engagement portion. The geometric locking engagement can be implemented in different ways, which will be described in detail below.

[0066] According to one embodiment, the geometric locking engagement is at least partially defined by a protruding structure of the cutting element being inserted into an associated recess of the annular engagement portion, wherein the protruding structure and the associated recess have complementary shapes.

[0067] This is considered to be a preferred way to provide a locking engagement. This is achieved by providing complementary shapes on the cutting element and the annular engagement portion, respectively. This complementary shape can be a protrusion, which, when inserted into the recess, is locked to the recess only by the shape of the protrusion. A simple example can be a rod extending into a hole. A conceivable way to provide a locking engagement can be to provide a plurality of radially inwardly directed holes on the periphery of the annular engagement portion and allow the cutting element to extend into these holes. They can then be fixed to the annular engagement portion by bolting. As will be readily appreciated by those skilled in the art, the bolts will not absorb most of the torsional loads, instead, these loads will be absorbed by the hole-protrusion arrangement with complementary shapes.

[0068] According to one embodiment, the associated recess of the annular engagement portion is defined on its side surface. This may be advantageous as it allows for easier replacement. Providing the recess on the side surface of the annular engagement portion may reduce the risk of jamming between the annular engagement portion and the cutting element due to dirt and contaminants entering the recess.

[0069] According to one embodiment, each of the plurality of cutting elements comprises a cutting element retaining structure and an active cutting element attached thereto, wherein the active cutting element has the impact surface and wherein the protruding structure forms part of the cutting element retaining structure. This can be advantageous because it allows a more modular system. The dedicated cutting element referred to herein as the "active cutting element" allows for individual replacement without having to replace the rest of the cutting element (i.e., the cutting element retaining structure). However, during replacement, it is conceivable that it is easier to replace the entire cutting element including the active cutting element and the cutting element retaining structure with a new cutting element. However, once the cutting element is removed, it can be taken to a workshop or other dedicated facility, where the worn active cutting element can be replaced with a new cutting element and mounted on the cutting element retaining structure. Therefore, the same cutting element retaining structure can be used multiple times.

[0070] According to one embodiment, the cutting element holding structure includes a support portion that protrudes from the cutting element holding structure in a direction opposite to the tangential movement direction of the cutting element, and the support portion is arranged so that it is supported by the annular engagement portion. This can be advantageous because it further helps to absorb the torsional load applied to the cutting element during operation. When the cutting element impacts the material on the roller with the flange, the cutting element will be pushed backward. Since the cutting element is arranged in an annular engagement portion positioned radially inward from the impact point (i.e., at the impact surface of the cutting element), the cutting element will apply a torsional load at the position where the cutting element is arranged in the annular engagement portion. This will in turn cause the cutting element to strive to bend backward around this point. By providing a backward-facing protrusion on the cutting element, this bending will be offset by the protrusion supported by the annular engagement portion. To some extent, this can be considered as another geometric locking means. In some embodiments, the protrusion is supported by the annular engagement portion by direct contact with the annular engagement portion. In other words, the protrusion can abut against the annular engagement portion. In other embodiments, the protrusion is supported by the annular engagement portion by direct contact with one or more further elements, which in turn are in direct contact with the annular engagement portion. Thus, support may not require abutment.

[0071] According to one embodiment, the roller crusher further comprises a wear cover constructed and arranged to protect at least a portion of the rotatable cutting unit. Wear covers can be advantageous because they allow the rotatable cutting unit to be protected from the harsh environment in which it is intended to operate. Typically during operation of the crusher, in particular during the removal of accumulated material from the flanged rollers, there will be a high density of high-speed stones, sand and dust constantly impinging on the surface of the rotatable cutting unit, thereby increasing the risk of wear of the parts, as well as damage due to penetration into cavities and gaps, which can also increase the complexity of maintenance and replacement.

[0072] According to one embodiment, the roller crusher comprises a first group of wear-resistant covers constructed and arranged to protect a first side of a rotatable cutting unit, and a second group of wear-resistant covers constructed and arranged to protect a second side of the rotatable cutting unit, and wherein at least one of the first and second groups of wear-resistant covers has an edge wall for interconnecting the first and second groups of wear-resistant covers at an annular joint portion between a plurality of cutting elements when mounted on the rotatable cutting unit. The first group of wear-resistant covers may include two or more wear-resistant covers. The second group of wear-resistant covers may include two or more wear-resistant covers. The wear-resistant covers may be mounted on the rotatable cutting unit as a last step. This means that, for an embodiment having a cutting element releasably arranged on the annular joint portion, the cutting element is first arranged on the annular joint portion, after which the first and second groups of wear-resistant covers are mounted on the rotatable cutting unit. This has the advantage of allowing protection of a fastening system for releasably arranging the cutting element to the annular joint portion.

[0073] The wear shield may be made of hardened steel, hardened iron, hardened metal, carbide (tungsten carbide), or a highly wear resistant material such as a weld overlay.

[0074] It is conceivable to control the rotational speed of the rotatable cutting unit based on input from one or more sensors. Such a sensor may be, for example, a level sensor or a metering sensor configured to measure a characteristic of the flanged roller. However, alternatively or additionally, the rotational speed of the rotatable cutting unit may be controlled based on sensor data from the material removal device itself. For example, the rotational speed of the rotatable cutting unit may be controlled based on sensor data related to the rotational speed of the rotatable cutting unit and / or torsional strain in the material removal device.

[0075] According to one embodiment, the rotating device comprises a drive unit. The drive unit may be a motor, such as an electric motor. Alternatively, the drive unit may be pneumatically or hydraulically driven.

[0076] According to one embodiment, the rotary device further comprises a transmission system comprising a gearbox. The gearbox may be a high reduction ratio gearbox. For example, the gearbox may have a reduction ratio of 4, 6, 8, 10 or 12 times. However, it is conceivable to use a higher reduction ratio, such as 60, 80 or 100 times. This may be advantageous because it allows the use of a less powerful drive unit.

[0077] The rotatable cutting unit can be arranged at different positions relative to the flanged roller. Typically, the rotatable cutting unit can be arranged relative to the flanged roller at a 5 to 1 o'clock position defined when the rotation direction of the roller is clockwise.

[0078] According to one embodiment, the rotatable cutting unit is arranged relative to the flanged roller at a position defined between 9 and 12 o'clock when the direction of rotation of the roller is clockwise. This may be advantageous for some roller crushers in which access and / or fastening of the rotatable cutting unit is usually limited to the lower end.

[0079] According to one embodiment, the rotatable cutting unit is arranged relative to the flanged roller at a 6 to 9 o'clock position defined when the direction of rotation of the roller is clockwise. This may be advantageous for some roller crushers, in which access and / or fastening of the rotatable cutting unit is usually limited to the upper end, but this may also be advantageous because the accumulated material removed at this position is easily guided towards the roller crusher through the outlet chute together with the crushed material below the roller crusher and removed from the roller crusher.

[0080] According to one embodiment, the periphery of the rotatable cutting unit, seen between a pair of adjacent cutting elements of the plurality of cutting elements, has a radial extension which is at least 20 mm smaller than a smallest radial distance of the pair of adjacent cutting elements.

[0081] By "periphery of the rotatable cutting unit" is meant herein the radial extension of the rotatable cutting unit defined transversely to the axis of rotation.

[0082] Providing a perimeter that is at least 20 mm smaller than the minimum radial distance of the pair of adjacent cutting elements can be advantageous because it allows the removed buildup material to more easily leave the rotatable cutting unit. If the perimeter of the rotatable cutting unit is too close to the minimum radial distance of the pair of adjacent cutting elements, as seen between a pair of adjacent cutting elements of the plurality of cutting elements, there is a risk that the removed buildup material may become stuck between the perimeter and the envelope surface of the roller.

[0083] The minimum difference between the radial extension of the circumference of the rotatable cutting unit and the minimum radial distance of the pair of adjacent cutting elements, as seen between the pair of adjacent cutting elements, may vary with the roller diameter. The reason for this is that the crushing gap generally increases with the roller diameter, resulting in an excess of thicker buildup material being deposited on the flange and / or on the envelope surface of the roller at the end adjacent to the flange. It is conceivable that the above defined minimum difference must exceed the thickness of the buildup material. Thus, for a roller crusher with large crushing rollers, the above defined difference may have to be greater than 20 mm. The radial extension may be in the range of 20 to 150 mm less than the minimum radial distance of the pair of adjacent cutting elements.

[0084] According to a second aspect of the present disclosure, a method for operating a roller crusher according to the first aspect is provided, wherein the method comprises at least a step of at least partially removing material accumulated on the envelope surface of the roller at the end adjacent to the flange and / or on the flange by means of a material removal device.

[0085] Similarly, and corresponding to the first aspect disclosed above, the second aspect of the present disclosure will provide substantial advantages over prior art solutions.

[0086] Other objects, features and advantages of the present disclosure will appear from the following detailed disclosure, the attached claims and the drawings. Note that the present disclosure relates to all possible feature combinations.

[0087] In general, unless otherwise explicitly defined herein, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field. Unless otherwise explicitly stated, all references to "a / an / the [element, device, component, means, step, etc.]" should be publicly interpreted as referring to at least one instance of the element, device, component, means, step, etc. Unless explicitly stated otherwise, the steps of any method disclosed herein do not have to be performed in the exact order disclosed.

[0088] As used herein, "comprise", "comprises" and its variations are not intended to exclude other additives, components, integers or steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] The present disclosure will be described in more detail with reference to the accompanying drawings, which show examples of currently preferred embodiments of the present disclosure.

[0090] Figure 1 It is a perspective view of a roller crusher according to the prior art.

[0091] Figure 2A yes Figure 1 Schematic top view of the two rollers of a roller crusher.

[0092] Figure 2B is a schematic top view of two rollers of a prior art roller crusher according to an alternative embodiment.

[0093] Figure 3A is a top cross-sectional view of a section of a roller crusher according to the prior art

[0094] Figure 3B is a side view of a section of a roll crusher according to an embodiment of the present disclosure.

[0095] Figure 4 is a perspective view of a material removal device according to an embodiment of the present disclosure.

[0096] Figure 5Ais a perspective view of a roller crusher according to an embodiment of the present disclosure, the roller crusher having a flanged roller at the top. Figure 4 Material removal device.

[0097] Figure 5B is a perspective view of a roller crusher according to another embodiment of the present disclosure, the roller crusher having a flanged roller at the lower end side thereof. Figure 4 Material removal device.

[0098] Figure 6 yes Figure 4 A perspective view of a portion of a material removal device.

[0099] Figure 7 yes Figure 4 and Figure 6 A perspective view of a portion of a material removal device.

[0100] Figure 8 yes Figure 4 , Figure 6 and Figure 7 A perspective view of a cutting element support structure and associated cutting elements of a material removal device.

[0101] Fig. 9 is a perspective view of a cutting element support structure and associated cutting elements according to another exemplary embodiment of the present disclosure.

[0102] Fig.10 is a perspective view of a cutting element support structure and associated cutting elements according to yet another exemplary embodiment of the present disclosure.

[0103] Fig.11 is a perspective view of a cutting element support structure and associated cutting elements according to yet another exemplary embodiment of the present disclosure.

[0104] Fig.12 yes Fig.10 A three-dimensional view of a cutting element support structure and associated cutting elements.

[0105] Fig.13 is a perspective view of a wear cover according to an exemplary embodiment of the present disclosure.

[0106] Fig.14 is a perspective view of a material removal device according to another embodiment of the present disclosure.

[0107] Fig.15A is a schematic perspective view of a rotatable cutting unit of a material removal device relative to a flanged roller when the rotatable cutting unit is arranged at the top of the flanged roller and tilted at an inclination angle φ.

[0108] Fig. 15B yes Fig.15ASchematic side view of a rotatable cutting unit and a roller with a flange.

[0109] Fig. 15C When the rotatable cutting unit is arranged at the top of the flanged roller and at an oblique angle Schematic perspective view of a rotatable cutting unit of a material removal device relative to a flanged roller when tilted.

[0110] Fig.15D yes Fig. 15C Schematic top view of a rotatable cutting unit and a roller with a flange.

[0111] Fig.16A is a schematic side view of a rotatable cutting unit and a roller surface of a flanged roller for an operating mode in which the tangential speed V of the rotatable cutting unit is C Tangential velocity V to the roller surface R Opposite orientation.

[0112] Fig. 16B is a schematic side view of a rotatable cutting unit and a roller surface of a flanged roller for an operating mode in which the tangential speed V of the rotatable cutting unit is C Tangential velocity V to the roller surface R oriented in the same direction, and where V C Less than V R .

[0113] Fig. 16C is a schematic side view of a rotatable cutting unit and a roller surface of a flanged roller for an operating mode in which the tangential speed V of the rotatable cutting unit is C Tangential velocity V to the roller surface R oriented in the same direction, and where V C Greater than V R .

[0114] Fig.17A is a perspective view of a cutting element according to an exemplary embodiment.

[0115] Fig. 17B yes Fig.17A Exploded perspective view of the cutting element.

[0116] Fig.18A is a perspective view of a material removal device according to another embodiment of the present disclosure.

[0117] Fig.18B yes Fig.18A A perspective view of a rotatable cutting unit of a material removal device.

[0118] Fig. 18C yes Fig.18A A perspective view of a material removal device, wherein the rotatable cutting unit is omitted.

[0119] Fig.19A yes Fig.18A and 18B A perspective view of a portion of a rotatable cutting unit.

[0120] Fig.19B yes Fig.19A A side view of the portion of the rotatable cutting unit.

[0121] Fig.19C yes Fig.19A A top view of the portion of the rotatable cutting unit.

[0122] Fig. 20A is a perspective view of a portion of a rotatable cutting unit according to another embodiment of the present disclosure.

[0123] Fig. 20B yes Fig. 20A A side view of the portion of the rotatable cutting unit.

[0124] Fig. 20C yes Fig. 20A A top view of the portion of the rotatable cutting unit.

[0125] Fig.20D is formed Fig. 20A Exploded view of a cutting element of a portion of a rotatable cutting unit.

[0126] Fig.20E is formed Fig. 20A An exploded view of the active cutting elements and cutting element support structure of a portion of a rotatable cutting unit.

[0127] Fig.21A is a perspective view of a portion of a rotatable cutting unit according to another embodiment of the present disclosure.

[0128] Fig.21B yes Fig.21A A side view of the portion of the rotatable cutting unit.

[0129] Fig. 21C yes Fig.21A A top view of the portion of the rotatable cutting unit.

[0130] Fig.22A is a perspective view of a portion of a rotatable cutting unit according to another embodiment of the present disclosure.

[0131] Fig. 22B yes Fig.22A A side view of the portion of the rotatable cutting unit.

[0132] Fig. 22C yes Fig.22A A top view of the portion of the rotatable cutting unit.

[0133] Fig.23A is a perspective view of a portion of a rotatable cutting unit according to another embodiment of the present disclosure.

[0134] Fig. 23B yes Fig.23A A side view of the portion of the rotatable cutting unit.

[0135] Fig.23C yes Fig.23A A top view of the portion of the rotatable cutting unit.

[0136] Fig.24A is a side view of a rotatable cutting unit according to another embodiment of the present disclosure.

[0137] Fig. 24B yes Fig.24A A three-dimensional view of the rotatable cutting unit.

[0138] Fig.24C is formed Fig.24A and Fig. 24B A perspective view of a cutting element that is part of a rotatable cutting unit.

[0139] Fig.25 is a perspective view of two material removal devices located on opposite sides of a frame of a roll crusher according to another exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0140] The present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the present disclosure are shown. However, the present disclosure may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for purposes of thoroughness and completeness and to fully convey the scope of the present disclosure to those skilled in the art. The same reference numerals indicate the same elements throughout.

[0141] As discussed in the background section of this disclosure, flanges (such as Figure 1 , Figure 2A and Figure 2B , and discussed further below), a flange is arranged at each end of one of the grinding rollers (such as Figure 2A , and discussed further below), or by arranging a flange on each grinding roller (such as Figure 2BThe invention relates to a roller crusher which is a roller crusher having a plurality of rollers and a plurality of rollers. The roller crusher has a plurality of rollers and a plurality of rollers which are provided with ...

[0142] Reference Figure 1 , Figure 2A , Figure 2B , Figure 3A , Figure 3B and Figure 4 This is achieved entirely or at least in part by a roller crusher 1 having two substantially parallel rollers 3, 4, 3', 4' arranged to rotate towards each other in opposite directions and separated by a gap G, each roller having two ends. The roller crusher 1 further comprises a flange 36, 36' attached to at least one end of one of the rollers 3, 4, 3', 4', the flange 36, 36' extending in the radial direction of the rollers 3, 4, 3', 4' and having a height H above an envelope surface 37, 37 of the rollers 3, 4, 3', 4'. The roller crusher 1 further comprises a movement blocking device 20, 20a, 20b constructed and arranged to limit the gap G between the rollers 3, 4, 3', 4' to a minimum gap M. Furthermore, the roller crusher 1 further comprises a material removal device 100 having a rotatable cutter 110 positioned at one end of the flanged roller 3, 4, 3', 4', wherein the rotatable cutting unit 110 has a plurality of cutting elements 120 arranged tangentially around the rotatable cutting unit 110 at respective radial distances T from the axis of rotation A of the rotatable cutting unit 110. Each of the plurality of cutting elements 120 has an impact surface 131 arranged to face the material to be removed, and each impact surface comprises polycrystalline diamond (PCD).

[0143] Reference Figure 1 , Figure 2A , Figure 2B , Figure 3A , Figure 3B and Figure 4, which is also achieved in full or at least in part by a method for operating a roller crusher 1 having two substantially parallel rollers 3, 4, 3', 4', which are arranged to rotate towards each other in opposite directions, each roller having two ends, the roller crusher 1 further comprising a flange 36, 36', which is attached to at least one end of one of the rollers 3, 4, 3', 4, which flange 36, 36' extends in a radial direction of the roller 3, 4, 3', 4' and has a height H above an envelope surface 37, 37' of the roller 3, 4, 3', 4'. The disclosed method comprises at least the step of at least partially removing material accumulated on the envelope surface 37, 37' and / or on the flange 36, 36' at an end portion of the roller 3, 4, 3', 4' adjacent to the flange 36, 36' by means of a material removal device 100.

[0144] The material removal device 100 with the rotatable cutting unit 110 may be advantageous because it allows the removal of the accumulated material 41 on the envelope surface 37, 37' at the end portion of the roller adjacent to the flange 36, 36' and / or on the flange 36, 36' in a more efficient manner. The rotatable cutting unit 110 may be considered as a plurality of movable impact surfaces 131a, 131b, each of which is defined on a respective one of the plurality of cutting elements 120. During operation, the material 41 is removed due to the impact forces generated between the material accumulation 41 on the rollers 3, 4, 3', 4' and these impact surfaces 131a, 131b. The impact force will increase with increasing relative speed between the speed of the material accumulation 41 (i.e. determined by the tangential speed of the envelope surface 37, 37' of the flanged rollers 3, 4, 3', 4') and the speed of the impact surface 131a, 131b (i.e. determined by the tangential speed of the cutting elements 120 on the rotatable cutting unit 110). By providing a rotatable cutting unit 110, material removal does not rely solely on the impact force generated by the movement of the rollers 3, 4, 3', 4' relative to the material removal device 100 (as is the case when the material removal device is a fixed scraper and thus defines a fixed impact surface). Instead, by rotating the rotatable cutting unit 110, the impact surface 131a, 131b of the rotatable cutting unit 110 can itself obtain a considerable tangential speed. If the rotatable cutting unit 110 is caused to rotate in the same rotational direction as the rollers 3, 4, 3', 4' with flanges 36, 36', the impact force can be significantly increased, thereby allowing more effective and reliable material removal. Another advantage of the rotatable cutting unit 110 is that it allows the impact force to be adjusted for specific situations. For example, there may be situations where it is less desirable to have high impact forces. For such situations, the rotation speed of the rotatable cutting unit 110 can be reduced during material removal to reduce the impact force without affecting the operation of the crusher itself (i.e., the rotation speed of the rollers 3, 3' with flanges 36, 36' can be kept constant). In some cases, it is even desirable to reduce the impact force to a degree that exceeds that which can be achieved with a fixed scraper. For such situations, the rotatable cutting unit 110 can be rotated in a rotation direction opposite to the rotation direction of the rollers 3, 3' with flanges 36, 36'. Yet another advantage of the rotatable cutting unit 110 is that providing a plurality of cutting elements 120 increases the overall wear resistance of the material removal device 100 compared to a fixed scraper. A plurality of cutting elements 120 will share the wear, whereby a single cutting element 120 will have a longer life expectancy. This allows increasing the operating time period before maintenance of the material removal device, thereby reducing the downtime of the roller crusher 1.

[0145] Figure 1A roller crusher 1 according to the prior art is shown. Such a roller crusher 1 comprises a frame 2 in which a first crushing roller 3 fixed is arranged in bearings 5, 5'. The bearing housings 35, 35' of these bearings 5, 5' are fixedly attached to the frame 2 and are therefore immovable. The second crushing roller 4 is arranged in bearings 6, 6' in the frame 2, which are arranged in the frame 2 in a slidable manner. The bearings 6, 6' can be moved in the frame 2 in a longitudinal direction perpendicular to the crushing roller 3 and the second crushing roller 4. Typically, guide structures 7, 7' are arranged in the frame on a first side 50 and a second side 50' along the upper and lower longitudinal frame elements 12, 12', 13, 13' of the roller crusher 1. The bearings 6, 6' are arranged in movable bearing housings 8, 8', which can slide along the guide structures 7, 7'. Furthermore, a plurality of hydraulic cylinders 9, 9' are arranged between the movable bearing blocks 8, 8' and first and second end supports 11, 11', which are arranged at or near the first end 51 of the roller crusher 1. These end supports 11, 11' are attached to upper and lower longitudinal frame elements 12, 12', 13, 13' and also serve as support for the forces generated at the hydraulic cylinders 9, 9' when the hydraulic cylinders 9, 9' adjust the gap width and react against the forces generated at the crushing rollers 3, 4 due to the feeding of material into the roller crusher 1.

[0146] This roller crusher works according to a technique called inter-particle crushing. The crushing rollers 3, 4 rotate in opposite directions to each other. Figure 1 The gap between the crushing rollers 3 and 4 is adjusted by the interaction of the feed load and the hydraulic system that affects the position of the second crushing roller 4. Figure 1 and the rollers 3 and 4 are shown in a top view. Figure 2A As shown, one of the grinding rollers 3 further includes flanges 36, 36' arranged at two opposite ends of the grinding roller 3, wherein each flange 36, 36' has a height H (see FIG. Figure 3A and 5A )'s outer edge and is positioned on the axial outside of the roller body of the opposite grinding roller 4.

[0147] Another prior art roller crusher is disclosed in, for example, WO 2013 / 156968, wherein each grinding roller having a bearing is arranged in interconnected arched frame sections, wherein each interconnected arched frame section is pivotably connected to a base frame. The subject matter disclosed in the present disclosure is equally applicable to such prior art roller crusher arrangements.

[0148] Likewise Figure 3AAs shown, each flange 36 is arranged at one end of the roller 3 so that the inner surface 39 of the flange 36 is located at a distance F from one end of the opposite roller 4. The distance F is necessary to avoid contact between the flange 36 and the roller 4, which may cause material damage. At the same time, the distance F should not be too large, because this would increase the risk of the material leaving the roller crusher through the gap G formed thereby. The distance F can be achieved by mounting the flange 36 on the roller 3 via the spacer 15, as shown in FIG. Figure 3A The purpose of the flanges 36, 36' is to prevent the material from flowing out from one end of the gap G, thereby forcing all the material entering the roller crusher to pass through the crushing gap G for crushing. Figure 2B An alternative embodiment of a roller crusher with flanges is shown. The only difference between the two embodiments is that Figure 2B The roller crusher in the embodiment has a flange 36 arranged on the second grinding roller 4' (rather than the first grinding roller 3'), which means that each grinding roller 3', 4' has a flange 36, 36'. As will be readily understood by those skilled in the art, the technical effect of preventing the material from leaving the crusher 1, 1' at both ends of the gap G will be equally well achieved for both disclosed embodiments. Importantly, the disclosed inventive concept is equally applicable to both embodiments.

[0149] As previously mentioned, a problem with this type of grinding assembly is that material tends to accumulate in the corner 40 between the outer surface 37 of the grinding roller 3 and the inner surface 39 of the flanges 36, 36' (see FIG. Figure 3A ) at. Figure 3A The schematic diagram shows the Figure 1 and Figure 2A This material accumulation 41 of the roller crusher 1 is not present and is generally undesirable because it creates an increased local load in this area during operation, which may cause wear, damage and / or deformation on the opposite grinding roller 4 without flanges, and may also cause strain and / or deformation of the flanges 3, 3'. In order to provide a solution to this problem, means for removing at least a portion of this accumulated material 41 are provided.

[0150] Figure 3B The rotatable cutting unit 110 of the material removal device 100 according to an embodiment of the present disclosure is schematically shown. Figure 4, to which the reader may also refer. The material removal device 100 will be described in detail later. In order to describe its material removal function, it is sufficient to mention that the material removal device 100 has a rotatable cutting unit 110 and that the rotatable cutting unit 110 has a plurality of impact surfaces 131a, 131b. When the rotatable cutting unit 110 rotates, the plurality of impact surfaces 131a, 131b will impact with the accumulated material 41 at the roller 3 having the flange 36, which will result in the material removal device 100 being able to cut material from the accumulation 41. The nature of the material accumulation 41 and the speed at which the impact surfaces 131a, 131b and the material accumulation 41 meet tend to cause the material removal to be essentially driven by impact. Therefore, when encountering the impact surfaces 131a, 131b, a large surface portion of the material accumulation 41 is more or less instantly destroyed, rather than forming a carved recess in the accumulated material 41. This is in Figure 3B Schematically shown in . It has been found that the remaining portion of the material accumulation 41 has a relatively uniform outer surface. It is generally not necessary to completely remove the material accumulation 41. Preferably, only a portion of the accumulation 41 should be removed. The partial removal of the material accumulation 41 will reduce the overall wear of the rotatable cutting unit 110 because the rotatable cutting unit 110 is subjected to significantly less wear when it is positioned farther away from the roller surface 37 and the flange 36. However, the positioning of the rotatable cutting unit 110 relative to the roller 3 and the flange 36 is not the focus of the present disclosure, and the rotatable cutting unit 110 can be positioned in many different ways depending on the application.

[0151] In the roll crusher (especially Figure 3A and Figure 3B Having described the function of the material removal device in the context of the roller 3 with flange 26 shown, reference will now be made to Figures 4 to 13 Describe the material removal device in detail.

[0152] Figure 4 A material removal device 100 according to an exemplary embodiment of the present disclosure is shown. Figure 4 In the embodiment shown, all parts of the material removal device 100 are shown, which means that some parts will inevitably obscure other parts. Therefore, we have referred to the figure showing the internal parts of the material removal device 100. Figure 6 , showing the outer part of the rotatable cutting unit 110 of the material removal device 100 Figure 7 , showing one of the cutting element support structures 140 of the material removal device 100 Figure 8 , and a diagram showing wear covers 160 , 165 of material removal device 100 Fig.13 .

[0153] The material removal device 100 consists of three main parts: a rotatable cutting unit 110, attached to a rotating shaft 150 supported by brackets 151a, 151b; a transmission system 180, connected to the rotating shaft 150; and a rotating device 190, which may include a drive unit 195 connected to the transmission system 180. The drive unit 195 may be a motor, such as an electric motor. Alternatively, the drive unit 195 may be pneumatically or hydraulically driven. The transmission system 180 may include a gear box 185 (in Figure 4 Schematically shown in ). The gearbox 185 can be a high reduction ratio gearbox 185. For example, the gearbox 185 can have a reduction ratio of 4 times, 6 times, 8 times, 10 times or 12 times. However, it is conceivable to use a higher reduction ratio, such as 60 times, 80 times or 100 times. This can be advantageous because it allows the use of a less powerful drive unit 195.

[0154] The material removal device 100 is mounted on the roller crusher 1 so that the rotatable cutting unit 110 is located at the preferred material removal area at the roller 3 having the flange 36. Figure 5A and Figure 5B As schematically shown in Figure 5A and Figure 5B Two conceivable positions for positioning the material removal device 100 relative to the roller 3 rotating about the rotation axis F are shown. Figure 5A In FIG. 1 , the material removal device 100 is located at the top of the roll crusher, at or near the 12 o'clock position defined when the direction of rotation of the roll is clockwise. Figure 5B In the embodiment of the present invention, the material removal device 100 is alternatively located at the bottom side of the roll crusher, at approximately the 8 o'clock position defined when the direction of rotation of the rolls is clockwise. There are advantages associated with both positions, and the decision of where to position the material removal device 100 may depend more on the specific constraints and requirements of the roll crusher than on cutting efficiency alone. Likewise, the approximately 12 o'clock position may be advantageous for some roll crushers where access and / or fastening of the rotatable cutting unit is generally limited at the lower end, while the approximately 8 o'clock position may be advantageous for some roll crushers where access and / or fastening of the rotatable cutting unit is generally limited at the upper end, because the accumulated material being removed at this position is easily guided toward and removed from the roll crusher through the outlet chute together with the crushed material below the roll crusher.

[0155] The rotatable cutting unit 110 will now be described in detail with reference to the above-mentioned drawings. The rotatable cutting unit 110 has a plurality of cutting elements 120 arranged tangentially around the rotatable cutting unit 110 at respective radial distances T from its rotation axis A (see FIG. Figure 4). Each cutting element 120 has an impact surface 131a, 131b arranged to face the material to be cut off. The rotatable cutting unit 110 is arranged to rotate about the cutting unit rotation axis A along the rotation direction R. When rotating in this way, the impact surfaces 131a, 131b will come into contact with the material accumulation 42 at the roller 3 with the flange 26 and cut off at least a part thereof, as previously described with reference to Figure 3A and Figure 3B Described in detail. Figure 7 The rotatable cutting unit 110 is shown having twelve cutting elements 120. However, fewer or more cutting elements are contemplated, and some exemplary embodiments showing this will be discussed later.

[0156] like Figure 4 As shown, the periphery 153 of the rotatable cutting unit 110 , viewed from between a pair of adjacent cutting elements 120 of the plurality of cutting elements 120 , has a radial extension K that is at least 20 mm smaller than a minimum radial distance T between the pair of adjacent cutting elements 120 .

[0157] Providing a perimeter 153 that is at least 20 mm smaller than the minimum radial distance T of the pair of adjacent cutting elements 120 can be advantageous because it makes it easier for the removed accumulated material 41 to leave the rotatable cutting unit 110. If the perimeter 153 of the rotatable cutting unit 110 is too close to the minimum radial distance K as seen between the pair of adjacent cutting elements 120, there is a risk that the removed accumulated material 41 may get stuck between the perimeter 153 and the envelope surface 37 of the roller 3.

[0158] The minimum difference (TK) between the radial extension K of the periphery 153 of the rotatable cutting unit 110 seen between the pair of adjacent cutting elements 120 and the minimum radial distance T of the pair of adjacent cutting elements 120 may vary with the roller diameter. The reason for this is that the crushing gap G generally increases with the roller diameter, which results in a greater excess of accumulated material with a greater thickness accumulating on the flange 36 and / or on the envelope surface 37 at the end portion of the roller 3 adjacent to the flange 36. It is to be taken into account that the above defined minimum difference must exceed the thickness of the accumulated material 41. Therefore, for a roller crusher 1 with a large crushing roller, the above defined difference may have to be greater than 20 mm. The radial extension may be in the range of 20 to 150 mm less than the minimum radial distance of the pair of adjacent cutting elements 120.

[0159] As will be readily appreciated by those skilled in the art, the above features may be less relevant for some exemplary embodiments than for other exemplary embodiments. Specifically, the above features may be less relevant for a rotatable cutting unit having fewer cutting elements than for a rotatable cutting unit having a greater number of cutting elements.

[0160] The cutting element 120 may be releasably arranged on the rotatable cutting unit 110. Figure 7 As shown, they are releasably attached to a specific portion of the rotatable cutting unit 110, referred to herein as the "annular joint portion 142". The annular joint portion 142 defines the outermost portion of the structure that supports the cutting elements 120. For the exemplary embodiment, the annular joint portion 142 is defined by the outermost portions of three separate elements, referred to herein as the cutting element support structure 140. This will be described in more detail later. However, for the purpose of releasably arranging the cutting elements 120, it is only necessary to provide such an annular joint portion. For alternative embodiments, this can also be represented by the outermost portion of a circular wheel or disc. Turning again to the rotatable cutting unit 110, the releasable arrangement of the cutting elements 120 in the annular joint portion 142 is achieved by fixing each cutting element 120 to the annular joint portion 142 with a fastening bolt 128. However, there are other important features associated with this joint. As Fig.12 As best shown in FIG. 1 (which relates to another exemplary embodiment but shows the same scheme), the annular engagement portion 142 includes a recess 143, 343 having a shape that is complementary to the shape of the cutting element 120, 220 inserted therein. Specifically, the cutting element 120, 220 includes a protruding structure 124, 224, which is configured to be inserted into the recess 143, 343 of the annular engagement portion 142, 242, 342. As will be readily appreciated by those skilled in the art, this arrangement will provide a geometrically locked engagement. If the cutting element 120 is secured to the annular engagement portion 142 in this manner, the tightening bolt 128 will not have to bear the entire load during operation of the material removal device 100. Most of the load will be borne by the geometrically locked engagement itself. For the exemplary embodiment shown herein, the associated recess of the annular engagement portion 142 is defined on its side surface 139. However, it is conceivable to provide the geometric locking engagement in other ways, such as by providing a plurality of radially inwardly directed holes on the periphery of the annular engagement portion and allowing the cutting elements to extend into these holes.

[0161] Fig.12It is also clearly shown in the figure that the cutting element 220 includes two independent structures, namely, the cutting element retaining structure 222 and the active cutting element 230. Although some features may differ between the exemplary embodiments provided herein, all exemplary embodiments of the cutting element retaining structures 122, 222 have similar geometric locking engagements. They also have similar shapes at the other end. Specifically, each cutting element retaining structure 122, 222 has a support surface 126, 226 to which the active cutting element 130, 230 is attached. In addition, the active cutting element 130, 230 has an impact surface 131a, 131b, 231a, 231b. For Figure 7 1, the support surface 126 is shown on the right side of the figure, but is mostly covered by the active cutting element 130. The cutting element 120 also includes a support portion 125, which protrudes from the cutting element holding structure 122 in a direction opposite to the tangential movement direction Y of the cutting element 120. This is also Figure 7 The support portion 125 is arranged to be supported by the annular engagement portion 142. When viewed alone Figure 7 This may not be obvious when the annular engagement portion 142 and the support portion 125 are clearly visible in the figure. However, as will be described in detail later, for the sake of clarity, Figure 7 Some elements have been omitted (specifically: wear-resistant covers 160, 165 have been omitted). The reader can refer to Figure 4 , where all components are shown. Figure 4 In the embodiment, it is clear that each support portion 125 abuts against the surface of the internal structure. Therefore, for the exemplary embodiment, the support portion 125 is supported by the annular engagement portion 142 via the wear shields 160, 165 inserted therebetween. The wear shields 160, 165 can be made of hardened steel, hardened iron, hardened metal, carbide (tungsten carbide) or a highly wear-resistant material such as a weld overlay.

[0162] Now go to Figures 8 to 11 , various exemplary embodiments of functional cutting elements will be discussed. Figure 8 1 shows a portion of a rotatable cutting unit 110, i.e., the first exemplary embodiment of a rotatable cutting unit discussed herein. The cutting element 120 of this exemplary embodiment includes an active cutting element 130 having a specific shape. Specifically, the active cutting element 130 has an impact surface 131a, 131b consisting of two separate parts, i.e., a front portion 131a and a rear portion 131b. The front portion 131a and the rear portion 131b are connected to each other. As shown in FIG. Figure 4 As best shown in FIG. 1 , the front portion 131a is arranged upstream of the rear portion 131b relative to the tangential movement direction Y of the cutting element 120. Figure 5A and Figure 5B As best shown, the front portion 131a is arranged closer to the flange 36 than the rear portion 131b. The reason for this specific design is to provide more effective cutting. During operation, the front portion 131a will first impact with the material to be removed. The smaller surface area of ​​the front portion 131a allows for higher local impact forces to be generated in the accumulated material, thereby increasing the likelihood of cutting off a large portion from the roller 3 and / or the flange 36. Once cut off, the rear portion 121b will encounter the loose material and transport it inward from the flange. This can reduce the risk of the same material getting stuck again and / or remaining in an area that affects further cutting operations at the flange 36. In order to further enhance this propeller or turbine effect, the rear portion 121b can be bent inwardly to form a bowl or concave shape. A second exemplary embodiment of an active cutting element is Fig.10 , that is, active cutting element 230. Active cutting element 230 differs from active cutting element 130 only in that the rear portion 231b of the impact surface is substantially flat and forms an oblique angle relative to the tangential motion direction Y of cutting element 220. As will be readily appreciated by those skilled in the art, this design will also provide a propeller or turbine effect. Fig.10 The angle γ is defined in the cutting element 220 as an angle γ and is defined between the rear portion 231b of the impact surface and the reference plane RR, in which the rotatable cutting element extends. The angle γ is defined in a tangential plane TPS of the cutting element 220, which is orthogonal to the reference plane RR. Fig.10 In the exemplary embodiment of FIG. , the angle γ is 45°. However, other angles are also possible. The angle γ will be further discussed later in conjunction with other exemplary embodiments of the present disclosure.

[0163] The third and final exemplary embodiment of a functional cutting element is Fig.11 , namely, an active cutting element 330. The active cutting element 330 differs from the active cutting elements 130, 230 in that it has only a single impact surface 331. In addition, the impact surface 331 is substantially flat and is arranged transversely to the tangential movement direction Y of the cutting element 320. The cutting element retaining structure 322 is similar to the cutting element retaining structure 122, but without the support portion 125. The active cutting elements 130, 230, 330 of the present disclosure may be made of a specific material suitable for withstanding high impacts. Such a material is typically a wear-resistant material, such as carbide. In particular, each active cutting element of the present disclosure includes polycrystalline diamond (PCD) on its impact surface 131, 231, 331, 431, 504, 604, 804, 1004, 1104. Reference will be made later Figures 18A-19C This is described in detail.

[0164] The active cutting element 130, 230, 330 may be attached to the cutting element retaining structure 122, 222, 322 by gluing or brazing. To provide further strength, a locking engagement may be used. Fig.17A and Fig. 17B Yet another exemplary embodiment of a cutting element is shown, namely cutting element 420, which has one such conceivable locking engagement. Cutting element 420 is similar to cutting element 320 and has similar structural features associated with the cutting operation. However, cutting element 420 differs from cutting element 320 in that cutting element 420 includes a cutting element retaining structure 422 having a protrusion 450 and an active cutting element 430 having a recess 452. Fig.17A and Fig. 17B As shown, the protrusion 450 and the recess 452 have complementary shapes. In addition, these shapes are selected to provide a locking engagement between the active cutting element 430 and the cutting element retaining structure 422. As will be readily appreciated by those skilled in the art, except for Fig.17A and Fig. 17B In addition to the shapes shown, there are many alternative shapes that can provide a locking engagement. To further enhance the connection between the active cutting element 430 and the cutting element retaining structure 422, once the protrusion 450 of the cutting element retaining structure 422 has been inserted into the recess 452 of the cutting element 430, the active cutting element 430 and the cutting element retaining structure 422 can be glued together.

[0165] As previously mentioned, the rotatable cutting unit 110 is an assembly consisting of a plurality of interconnected elements. So far, the focus has been on the cutting elements 120, 220, 320. Now, reference will be made to Figure 6 , Figure 7 and Figure 8 The inner portion of the rotatable cutting unit 110 is described in detail. Figure 6 A rotating shaft 150 is shown supported in its brackets 151a, 151b. Figure 6 Also shown is a shaft cap 152 mounted on the rotating shaft 150 to maintain it at a predetermined axial position within the brackets 151a, 151b. Figure 6 Further shown is the very inner portion of the rotatable cutting unit 110, referred to herein as the main support structure 112. The main support structure 112 is a steel element in this exemplary embodiment, which includes an inner portion 113 that is configured to be fixed to the shaft by fastening bolts 115. Although Figure 6Not shown in the figure, the rotating shaft 150 includes a fastening portion (not shown) protruding radially outward from the surface of the shaft 150. The fastening portion can be welded into the shaft 150 during its manufacturing process. The main support structure 112 has a central opening 119, the diameter of which is large enough to allow the rotating shaft 150 to be inserted therein during assembly. Once in place, the main support structure 112 is fixed to the fastening portion of the rotating shaft 150 by a fastening bolt 115 inserted through the through hole 114. As those skilled in the art will readily appreciate, when installed on a roll crusher, the main support structure 112 is not easily removed. Alternatively, the main support structure 112 is designed to withstand long-term operation. However, the releasable arrangement of the main support structure 112 to the rotating shaft 150 will allow the main support structure 112 to be replaced separately when necessary. The outer portion 116 of the main support structure 112 includes a plurality of threaded holes 117 and a plurality of through holes 118. These are used to fix external elements to the main support structure 112 and will be discussed in more detail later.

[0166] For all of the exemplary embodiments discussed herein, the cutting elements 120 are attached to the main support structure 112 via a series of specialized support structures, referred to herein as "cutting element support structures" 140. Thus, the inner ends of these structures are mounted on the main support structure 112 and have an annular engagement portion 142 at their outer ends where the cutting elements 120 will be releasably disposed. Figure 7 The outer portion of the rotatable cutting unit 110 is shown and includes these aforementioned structures, for this specific exemplary embodiment: including three cutting element support structures 140. For clarity, one of the cutting element support structures 140 is also shown. Figure 8 As shown in Figure 7 As clearly shown in the figure, the rotatable cutting unit 110 includes at least two cutting element support structures 140 (for this exemplary embodiment: includes three cutting element support structures 140). The at least two cutting element support structures 140 are releasably arranged relative to the main support structure 112 and are shaped as circular ring sectors that together form a circular ring. The circular ring has an annular joint portion 142. The purpose of providing two or more cutting element support structures 140 is to allow them to be replaced individually on site without having to completely disassemble the material removal device 100. As will be seen later, there are many conceivable ways to provide the cutting element support structures 140 of the present disclosure. They can appear in different numbers, have different shapes, and support different numbers of cutting elements 120. The cutting element support structures 140 have a 120-degree circular ring sector design, so three cutting element support structures 140 are required to completely surround the main support structure 112 to form the annular joint portion 142.

[0167] The cutting element support structure 140 includes an inner portion 145 having a plurality of first through holes 146 and a plurality of second through holes 147. The purpose of the first through holes 146 is to provide a means of securing the cutting element support structure 140 to the main support structure 112 by means of fastening bolts 148. Figure 7 The purpose of the second through hole 147 will be disclosed later. The cutting element support structure 140 also includes an outer portion 141, which includes one or more recesses 143 (for the exemplary embodiment: four recesses 143). Each recess has a threaded hole 144 (see Fig.12 ) for receiving the fastening bolt 128. The recess 143 has been described in detail when describing the cutting elements 120 and how these cutting elements are attached, and will not be further described here. Figure 7 As shown, the outer portions 141 of the three cutting element support structures 140 together define the annular joint portion 142 of the present exemplary embodiment. Therefore, in this case, the annular joint portion 142 is defined together by three adjacent elements of the assembly. Similarly, those skilled in the art will understand that embodiments with fewer or more cutting element support structures (e.g., 2, 4 or 6 cutting element support structures) will have associated annular joint portions defined by a different number of cutting element support structures. When assembled on the main support structure 112, the cutting element support structures 140 together define a central opening 149. The central opening 149 allows the rotational axis 150 to pass through the assembly defined by the cutting element support structures 140. From Figure 7 and Figure 8 As can be seen in FIG. 1 , when viewed along the cutting unit rotation axis A, the thickness of the outer portion 141 is greater than the thickness of the inner portion 145. This design allows a recess to be formed for accommodating the main support structure 112 when the main support structure 112 is installed. This is Figure 7 , where the primary support structure 112 has been removed for clarity, but the bolt heads of the fastening bolts 148 still mark the location of the outermost surface of the primary support structure 112 when assembled together.

[0168] Now turn to Fig. 9 and Fig.10 , some alternative exemplary embodiments of cutting element support structures will be described. First, in Fig. 9 , a cutting element support structure 240 is shown together with three cutting elements 120 that are similar to those used in the first exemplary embodiment. Figure 8140. The cutting element support structure 240 is the same as the cutting element shown in . The difference between the cutting element support structure 140 and the cutting element support structure 140 is that it only has three recesses 143 for the releasable arrangement of the cutting element 120, and the cutting element support structure 240 has a 90-degree circular sector design, so four cutting element support structures 240 are required to completely surround the main support structure 112 to form an annular joint portion 242. As those skilled in the art will readily appreciate, the cutting element support structure 140 and the cutting element support structure 240 can be used to assemble a rotatable cutting unit having substantially the same features. Three cutting element support structures 140 each having four recesses 143 will provide a rotatable cutting unit 110 having twelve cutting elements 120. Similarly, four cutting element support structures 240 each having three recesses 143 will also provide a rotatable cutting unit 110 having twelve cutting elements 120. In other words, the annular joint portion 142 and the annular joint portion 242 will have similar interfaces for the cutting element 120.

[0169] Fig.10 A further exemplary embodiment of a cutting element support structure is shown, namely cutting element support structure 340. Cutting element support structure 340 differs from cutting element support structure 140 in that it has six, rather than four, recesses 343. It has the same outer dimensions as cutting element support structure 140, so a similar set of three cutting element support structures 340 is required to completely surround the main support structure 112 to form the annular engagement portion 142, so cutting element support structure 340 allows a rotatable cutting unit with 18 cutting elements 220 to be provided for defining the annular engagement portion 342. In order to accommodate a greater number of cutting elements 120, 220, recess 343 is not as wide as recess 143. This means that a cutting element 220 with a cutting element retaining structure 222 will also be less wide in order to fit into recess 343, thereby providing a geometrically locked engagement. Fig.11 Shows Figure 8 The cutting element support structure 140 is different from the cutting element support structure 140 of FIG. 1 , but here it is equipped with the aforementioned cutting element 320.

[0170] In order to protect the rotatable cutting unit 110, the aforementioned wear-resistant covers 160, 165 are provided. Fig.13 , where they are shown individually. Figure 4A rotatable cutting unit 110 equipped with wear-resistant covers 160a-160c, 165a-165c is shown, and it is suggested that these figures be read together. The wear-resistant covers 160a-160c, 165a-165c include a first group of wear-resistant covers 160a-160c and a second group of wear-resistant covers 165a-165c. Each of these groups includes two or more wear-resistant covers 160a-160c, 165a-165c. As for the cutting element support structure, the wear-resistant covers 160a-160c, 165a-165c are shaped as annular sectors that together form an annular ring, one on each side of the rotatable cutting unit 110. The wear-resistant covers of the first group of wear-resistant covers 160a-160c have openings 161 distributed mutually along their periphery. These openings are structures that allow the cutting elements 120 to protrude through the wear-resistant covers 160a-160c, 165a-165c, such as Figure 4 As shown. An edge wall 162 is provided between each of these openings 161. These edge walls 162 may protrude radially and axially, such as Fig.13 As best shown. The wear covers of the first set of wear covers 160a-160c may also have a threaded rod 163 protruding from the inwardly facing surface. When assembled together, the first set of wear covers 160a-160c together define a central opening 164 for allowing the rotation shaft 150 to pass through the first set of wear covers 160a-160c. Similarly, the second set of wear covers 165a-165c has openings 166 distributed along its periphery. An edge wall 167 is provided between each of these openings 166. In contrast to the edge wall 162, these edge walls 167 only protrude axially. The wear covers 160a-160c, 165a-165c are designed so that after being assembled on the rotatable cutting unit 110, the edge wall 162 will meet the edge wall 167 to form a continuous cover for protecting the inner part of the rotatable cutting unit 110 at its periphery. The second set of wear caps 165a-165c also has through holes 168 that are geometrically aligned to allow for receiving a corresponding one of the threaded rods 163 of the first set of wear caps 160a-160c. Finally, the second set of wear caps 165a-165c has access openings 169 that are aligned so that they allow for entry of the fastening bolts 148, as shown in FIG. Figure 4140. The wear caps 160a-160c, 165a-165c are designed so that they can be installed on the rotatable cutting unit 110 after the cutting element 120 has been installed on the rotatable cutting unit. This is achieved by sequentially inserting the threaded rods 163 of the wear caps of the first set 160a-160c into the through holes 118 of the main support structure 112 and the second through holes 147 of the cutting element support structure 140. Each through hole 118 and a corresponding one of the second through holes 147 are positioned so that they are coaxially aligned with each other and with an associated one of the threaded rods 163 of the first set of wear caps 160a-160c. Once each of the wear caps of the first set 160a-160c has been inserted into place, the second set 165a-165c of the wear caps is assembled from the other side of the main support structure 112 by allowing each threaded rod 163 to pass through the associated through hole 168. Finally, the fastening nuts 171 are used to secure the first set of wear covers 160a-160c to the second set of wear covers 165a-165c.

[0171] Fig.14 2 shows a material removal device 200 according to another exemplary embodiment of the present disclosure. The material removal device 200 is similar to Figure 4 The material removal device 100 shown differs only in how the rotatable cutting unit is supported. To better illustrate the differences, the same reference numerals define the same features as the material removal device 100, while different features are given new reference numerals in a new series.

[0172] The material removal device 200 is composed of three main parts: a rotatable cutting unit 110 attached to a rotating shaft 250 supported by a bracket 251; a transmission system 180 connected to the rotating shaft 250; and a drive unit 195 connected to the transmission system 180. The rotating device 190 including the transmission system 180 and the drive unit 195 is only Fig.18A 2 and is the same as previously described with reference to the material removal device 100. Thus, the rotatable cutting unit 110 is mounted or attached to a rotating shaft 250 which is not through-going as the rotating shaft 150 of the first exemplary embodiment. This arrangement has the advantage that it is easier to replace the rotatable cutting unit. This also facilitates the use of higher tilt angles, which will be further described below.

[0173] The cutting unit rotation axis A is preferably parallel to the rotation axis F of the roller 3. However, it is conceivable that the cutting unit rotation axis A is angled relative to the rotation axis F of the roller 3. Figures 15A-15D Shown in.

[0174] Fig.15A and Fig. 15BOne way of angling the rotatable cutting unit 110 relative to the roller 3 is shown. This way of angling the rotatable cutting unit 110 is referred to herein as tilting. Tilt herein means that the rotatable cutting unit 110 is arranged so that the cutting unit rotation axis A forms an inclination angle φ relative to the roller rotation axis F in a radial plane RP of the roller, which intersects the cutting unit rotation axis A. This means that the rotatable cutting unit 110 will not be parallel to the flange 36 of the roller 3, resulting in a variation in the distance between the rotatable cutting unit 110 and the flange 36 in the radial direction of the roller, as shown in FIG. Fig. 15B The tilt angle φ may be in the range of 0 to 90 degrees, preferably in the range of 0 to 45 degrees. For larger tilt angles φ, the material removal device 200 may be more suitable than the material removal device 100 because it does not have a through shaft.

[0175] Fig. 15C and Fig.15D Another way of angling the rotatable cutting unit 110 relative to the roller 3 is shown. This way of angling the rotatable cutting unit 110 is referred to herein as skew. Skew herein means that the rotatable cutting unit 110 is arranged so that the cutting unit rotation axis A forms a skew angle relative to the rotation axis F of the roller 3 in the tangential plane TP of the roller 3. This tangential plane TP is orthogonal to the radial plane RP of the roller 3, which intersects the cutting unit rotation axis A. This means that the rotatable cutting unit 110 will not be parallel to the flange 36, resulting in a variation in the distance between the rotatable cutting unit 110 and the flange 36 along the tangential direction of the roller surface 3, such as Fig.15D Best shown. Skew angle It can be in the range of 0 to 20 degrees, preferably in the range of 0 to 15 degrees. Preferably, the deflection angle The distance between the rotatable cutting element 110 and the flange 36 is defined so that it is smallest at the upstream end of the material removal device 100. This may be advantageous because since the distance between the rotatable cutting element 110 and the flange 36 is wider at the downstream end of the material removal device, this may help to remove broken-off accumulated material at the downstream end.

[0176] The rotatable cutting unit 110 can rotate in the same direction of rotation as the roller 3 with the flange 36. Alternatively, the rotatable cutting unit 110 can rotate in a direction of rotation opposite to the direction of rotation of the roller 3 with the flange 36. The rotation speed of the rotatable cutting unit 110 can be in the range of 1 rpm to 200 rpm. As will be readily appreciated by those skilled in the art, an important factor will be the relative difference in tangential velocity between the roller surface and the cutting element of the rotatable cutting unit at the point of impact therebetween. This is particularly important in Figure 16A-16CThe tangential velocity of the rotatable cutting unit 110 is denoted as V in this document. C , and the tangential velocity of the roller surface 37 of the roller 3 is represented by V R .

[0177] If the rotatable cutting unit 110 rotates in the same direction as the roller 3 with the flange 36 ( Fig.16A ), the maximum relative difference in tangential velocity will usually be obtained. This is because the two tangential velocities V R and V C If the rotatable cutting unit 110 rotates in a direction opposite to the direction of rotation of the roller 3 with the flange 36, the relative difference in the tangential speeds will be lower. This is because the two tangential speeds V R and V C Results pointing in the same direction, such as Fig. 16B and 16C As shown in Figure 2, it can be seen that there are two different situations. Fig. 16B shows the tangential velocity V C and V R points in the same direction, but the tangential velocity V of roller 3 R Greater than the tangential speed V of the rotating cutting unit 110 C In this speed range, material accumulation present on the roller surface will move faster than the impact surfaces 131a, 131b of the rotatable cutting unit 110. This mode of operation can be used in situations where material accumulation is not excessive. By rotating the rotatable cutting unit 110 constantly, each cutting element will be worn to the same extent and will contribute to cutting equally, but at a lower speed. As will be readily understood by those skilled in the art, and also as Fig.16A and Fig. 16B As shown, for both cases, the impact surfaces 131a, 131b of the cutting elements are oriented in the same direction. Fig. 16C A third possible case is shown, which shows the tangential velocity V C and V R points in the same direction, but the tangential velocity V of roller 3 R is less than the tangential speed V of the rotating cutting unit 110 C In this speed range, the material accumulation present on the roller surface will move slower than the impact surfaces 131a, 131b of the rotatable cutting unit 110. This mode of operation has the advantage that the removed material and dust generated in the process are directed inwardly towards the crusher gap, which may be advantageous for some applications.

[0178] for Fig. 16B and Fig. 16CIn the case of reverse rotation shown, at a certain ratio between the rotation speed of the roller 3 and the rotation speed of the rotatable cutting unit 110, the relative difference in tangential speed will be zero (i.e. V C =V R ), which would result in a loss of cutting action. Therefore, care must be taken to avoid such rotational speeds when operating the rotatable cutting unit in a rotational direction opposite to the rotational direction of the roller 3. For an effective cutting operation, the relative tangential speed is preferably higher than 1.25 times the tangential speed of the roller surface.

[0179] Fig.18A 2 shows a material removal device 500 according to another exemplary embodiment of the present disclosure. The material removal device 500 includes a rotatable cutting unit 510. Fig.18B The rotatable cutting unit 510 shown separately in the figure has a plurality of cutting elements 501 (for this particular exemplary embodiment: eight cutting elements 501), which are arranged tangentially around the rotatable cutting unit 510 at corresponding radial distances T from the rotation axis A of the rotatable cutting unit 510. For this exemplary embodiment, the cutting elements 501 are equally spaced 45 degrees from each other. The rotatable cutting unit 510 has an annular joint portion 511, and each cutting element 501 is arranged to the annular joint portion 511. Each cutting element 501 can be attached to the annular joint portion 511 by bolting, threading, clamping, etc. The rotatable cutting unit 510 is attached to a rotatably arranged shaft member 540, which in turn is rotatably attached to a part of the roller crusher 1 via a support structure or bracket 550. As shown Fig.18A and Fig.19B As shown, the periphery 548 of the rotatable cutting unit 510, viewed from between a pair of adjacent cutting elements 501 of the plurality of cutting elements 501, has a radial extension K that is at least 20 mm smaller than the minimum radial distance T of the pair of adjacent cutting elements 501. Fig.18A In the exemplary embodiment shown, the radial distance T is the same for all eight cutting elements 501, so the minimum radial distance will be Fig.18A The radial distance T defined in .

[0180] The material removal device 500 further includes a transmission system 180 connected to the rotating shaft 540 and a drive unit 195 connected to the transmission system 180. The transmission system 180 and the drive unit 195 are only Fig.18A , and may be the same as previously described with reference to material removal device 100 .

[0181] like Fig.18AAs shown, the rotatable cutting element 510 is arranged at a first end 512 of the material removal device 500, and the rotating device 190 is arranged at an opposite second end 514 of the material removal device 500. The rotatable cutting element 510 extends in a reference plane RR that is orthogonal to the axis of rotation A. When observing the drawings, it will be clear that the reference plane RR is shown in different axial positions in different figures. This is done to make it easier to understand the geometry of the cutting element. However, the reference plane RR is always orthogonal to the axis of rotation A.

[0182] like 18A to 18C As shown, the rotatable cutting unit 510 includes a main support structure 112 and at least two cutting element support structures 520 (in the exemplary embodiment: four cutting element support structures 520). The cutting element support structures 520 are releasably arranged relative to the main support structure 112 and are shaped into circular ring sectors that together form a circular ring in the same manner as in the previous embodiments. Releasable attachment can be achieved by bolting these elements together with fastening bolts 148 that enter through holes 513 and are fixed to threaded holes 117 of the outer part 116 of the main support structure 112. The fastening bolts 148 are fixed to the threaded holes 117 of the outer part 116 of the main support structure 112. Fig.18A is not visible in the example described previously, but can be seen in Figure 4 In the exemplary embodiments and in Fig.25 The main support structure 112 of the rotatable cutting unit 510 is shown in the exemplary embodiment shown. Figure 6 The same is described, and the attachment of the cutting element support structure 520 to the main support structure 112 is achieved in exactly the same manner as previously described, and therefore will not be described further herein.

[0183] like Fig.18A As shown, the ring has an annular engagement portion 511. The purpose of providing two or more cutting element support structures 520 is to allow them to be replaced individually in the field without having to completely disassemble the material removal device 500, as previously described. There are many conceivable ways to provide cutting element support structures within the scope of the present disclosure. They can appear in different numbers, have different shapes, and support different numbers of cutting elements. The cutting element support structures 520 have a 90 degree annular sector design, so four cutting element support structures 520 are required to completely surround the main support structure 112 to form the annular engagement portion 511.

[0184] Each cutting element 501 includes a cutting element retaining structure 503 and an active cutting element 502, wherein the active cutting element 502 has a Fig.18A and Fig.18B The impact surface 504 is shown in the dotted area. The active cutting element 502 of the cutting element 501 has an impact surface 504 comprising polycrystalline diamond (PCD).

[0185] As will be readily appreciated by those skilled in the art, diamond can be a single continuous crystal, or it can be composed of many smaller crystals (polycrystals). Large, clear, and transparent single crystals of diamond are commonly used as gemstones. Polycrystalline diamond (PCD) is composed of numerous small particles that are easily visible to the naked eye through strong light absorption and scattering; it is not suitable for use as a gemstone, but is used in industrial applications such as mining and cutting tools. Polycrystalline diamond is often described by the average size (or grain size) of the crystals that make it up. Grain sizes range from a few nanometers to hundreds of micrometers, and are often referred to as "nanocrystalline" and "microcrystalline" diamond, respectively.

[0186] For cutting element 501, active cutting element 502 also includes a wear-resistant material in which polycrystalline diamond (PCD) is at least partially embedded. In an alternative embodiment, polycrystalline diamond (PCD) can be attached to the surface of the wear-resistant material of active cutting element 502. For an exemplary embodiment, the wear-resistant material is a sintered carbide including tungsten carbide and cobalt (as a binder). The binder content can typically be 10-15 weight percent. Other wear-resistant materials are also possible. Such alternative materials include other ceramic materials, such as titanium carbide or vanadium carbide; metal-ceramic composites, such as sintered carbides, such as titanium carbide, tungsten carbide or vanadium carbide, with cobalt as a binder; or metal matrix composites including titanium carbide, tungsten carbide or vanadium carbide.

[0187] In one embodiment, polycrystalline diamond (PCD) is embedded in tungsten carbide, vanadium carbide, or titanium carbide.

[0188] An advantage of an impact surface 504 comprising polycrystalline diamond (PCD) is that the wear life of the cutting element 501 can be significantly extended. Typically, such an impact surface 504 will include a wear-resistant material, such as ceramic or a composite material including tungsten carbide, titanium carbide, and vanadium carbide, but using an impact surface 504 comprising polycrystalline diamond (PCD), the wear life can be extended by up to about 50 times compared to a composite material comprising, for example, tungsten carbide alone.

[0189] The active cutting element 502 may include a layer of polycrystalline diamond (PCD). The layer of polycrystalline diamond (PCD) may have a thickness of 0.4 to 3.2 mm, or 1.0 to 2.0 mm, or 1.35 to 1.8 mm, or 1.4 to 1.6 mm, or about 1.5 mm.

[0190] According to one embodiment, the impact surface of the cutting element may include two or more layers of polycrystalline diamond (PCD). The two or more layers may be attached to each other, for example, by an adhesive. The number of layers and / or the thickness of each layer may depend on the particle size and / or its application.

[0191] The diamond grain size of the polycrystalline diamond (PCD) impacting the surface may be 0.8 to 30 μm as determined by image analysis using a scanning electron microscope (SEM).

[0192] The particle size of the diamond can be measured by various measurement techniques, such as a laser particle size analyzer or a scanning electron microscope (SEM). An example of a laser particle size analyzer is the Malvern particle size analyzer device based on laser diffraction. The value determined using the laser particle size analyzer can be the initial diamond particle size, which for some embodiments can then be subjected to high pressure and high temperature sintering. When the diamond grains have been sintered and compacted to form a polycrystalline diamond (PCD) impacting the surface, image analysis with the aid of a scanning electron microscope is used to determine the end microstructure particle size distribution, i.e. the diamond particle size of the polycrystalline diamond (PCD) impacting the surface.

[0193] This disclosure of the materials of impact surface 504 and active cutting element 502 also applies to impact surfaces 131, 231, 331, 431, 604, 804, 1004 and 1104 and active cutting elements 130, 230, 330, 430, 602, 802, 1002, 1102 as indicated by the dotted areas in the associated figures.

[0194] In addition to the active cutting element 502, each cutting element 501 of the material removal device 500 also includes a surface 506 facing the flange 36 (see Fig.18A ), the surface 506 comprises polycrystalline diamond (PCD). The surface 506 is defined on an element 505, which may be similar to the functional cutting element 502 already described in detail herein. It is also conceivable that the element 505 is different from the functional cutting element 502. For example, the PCD of the functional cutting element 502 may have different properties from the PCD of the element 505. This may be beneficial because the cutting element 502 will generally face the material to be removed and may therefore be primarily exposed to material impact, while the element 505 will be oriented so that the material will impact at a certain angle, which makes the element 505 more susceptible to sliding wear rather than impact wear. The rotatable cutting unit 510 is constructed and arranged so that each impact surface 504 at least partially faces a tangential motion direction Y defined at the impact surface 504 and oriented along the rotation direction R of the rotatable cutting unit 510. In other words, the impact surface 504 has a projection PP in a plane PA orthogonal to the tangential motion direction Y, and the projection PP is greater than zero. As will be readily appreciated by a person skilled in the art, this achieves the effect that when the material removal device 500 is arranged on a roller crusher 1 , the impact surface 504 can be arranged such that it at least partially faces the material to be removed.

[0195] Each cutting element 501 is releasably fastened to the cutting element support structure 520 by means of a bolt connection. The bolt connection allows for an easy assembly process when preparing the rotatable cutting unit 510 for installation on the roll crusher 1. The rotatable cutting unit 510 is attached to a shaft member 540, which is rotatably attached to a bracket 550. The bracket 550 is constructed and arranged to be connected to the frame 2 of the roll crusher 1.

[0196] like Fig.18A and FIG. 19A to FIG. 19C 3, which shows in more detail the individual cutting elements 501 of the material removal device 500, the surface 506 facing the flange 36 having an extension E2 from the active cutting element 502 tangentially toward its rear end 507. The cutting element 501 is constructed and arranged so that the distance L2 (see FIG. 5 ) between the surface 506 facing the flange 36 and the rotating device 190 is Fig.18A and Fig.19A ) decreases towards the impact surface 506 over at least a portion of the extension E2. The distance L2 is only Fig.19A Schematically shown by arrows and dashed boxes, it is intended to define the relative position of the rotating device 190 relative to the cutting element 501. However, Fig.18A The distance L2 is shown more realistically in FIG. Fig.19C The view in and the following Fig. 20C , Fig. 21C , Fig. 22C and Fig.23C The views in the Fig.19B The radial axis RA defined in is intercepted.

[0197] For an exemplary embodiment, surface 506 facing flange 36 is substantially flat. Therefore, for cutting element 501, the varying distance L2 as described above can be further represented by an angle β defined between surface 506 facing flange 36 and reference plane RR, wherein angle β is defined within a tangent plane TPS of cutting element 501 that is orthogonal to reference plane RR. Angle β can be 1° to 45°, 1° to 40°, 1° to 30°, 5° to 25°, or 5° to 20°, or 5° to 15°, or 8° to 12°, or 10°. Angle β of cutting element 501, reference plane RR, and tangent plane TPS are Fig.19A Shown in.

[0198] from Fig.19AAs can be seen in FIG, the tangential plane TPS of the cutting element 501 is parallel to the tangential direction Y of the cutting element 501, as defined at the impact surface 504 and oriented along the reference rotation direction R of the rotatable cutting unit 510, and the tangential plane TPS is orthogonal to the reference plane RR. Therefore, each cutting element 501 of the plurality of cutting elements 501 has an associated tangential plane TPS, and since the cutting elements 501 are tangentially arranged around the rotatable cutting unit 510, these tangential planes are angled relative to each other.

[0199] like Fig.19B As best shown in FIG. 1 , each cutting element 501 extends from a bottom end 517 along a cutting axis 514 in a reference plane RR toward an active cutting element 502. The cutting axis 514 forms a first acute angle A1 along a rotational direction R with a radial axis RA of the rotatable cutting unit 510 that intersects the active cutting element 502. Fig.19B As best shown, this achieves the effect of "tilting forward" the cutting elements 501 when the material removal device 500 is arranged in the roll crusher 1. Furthermore, each impact surface 504 extends in a plane SP having a normal NP which forms an acute angle A2 with the cutting axis 514 along the direction of rotation R. This further helps to turn the impact surface 504 towards the material to be removed when the material removal device 500 is arranged on the roll crusher 1.

[0200] like Fig.18A shown, and in Fig.19C As shown in more detail in FIG. 5 , the cutting element 501 is arranged to form an axial protrusion 515 on the side of the rotatable cutting unit 510 facing the flange 36. Fig. 18C As shown, the protrusion 515 has an axial extension X. The axial extension X may be in the range of up to 75 mm or 5 to 50 mm or 10 to 40 mm. Although the ranges disclosed above are currently preferred, it is conceivable that the axial extension X may also be greater than 75 mm. The axial extension may depend on the roller crusher 1, the operating conditions and the material to be crushed, among other things. Therefore, the axial extension X must be selected based on parameters such as (but not limited to) the crushing gap G, the size of the crushing rollers 3, 4 and the size of the accumulated material 41 to be removed. The larger the material accumulation 41, the larger the axial extension X may be required.

[0201] This particular exemplary embodiment has protrusions only on the side facing the flange 36. However, it is conceivable that multiple cutting elements are arranged to form axial protrusions on one or both sides of the rotatable cutting unit. The advantage of the protrusion 515 is that when the material removal device 500 is arranged and operated on the roller crusher 1, once the material to be removed flows along the surface 506 of the cutting element 501 facing the flange 36, the material will be easily removed through the wider gap between the inner surface 39 of the flange 36 and the remaining part of the rotatable cutting unit 510 (for the exemplary embodiment, the remaining part will be the main support structure 112 and the cutting element support structure 520) and flow to the center of the roller 3, rather than being squeezed and compressed between the rotatable cutting unit 510 and the inner surface 39 of the flange 36.

[0202] The material removal device according to the present disclosure can be implemented in a variety of different ways. FIG. 20A to FIG. 23C A number of alternative embodiments of cutting element assemblies 600, 700, 800, 900 are described in detail. A cutting element assembly 600, 700, 800, 900 is defined herein as a cutting element support structure 620 and its associated cutting elements 601, 701, 801, 901. Each of these cutting element assemblies 600, 700, 800, 900 may be secured to Fig.18C The main support structure 112 is shown. Providing the same interface for different cutting element assembly styles allows for varying the number of cutting elements on the rotatable cutting unit as well as the structure and features of the individual cutting elements attached to the cutting element support structure.

[0203] FIG. 20A to FIG. 20E A cutting element assembly 600 according to an alternative embodiment of the present disclosure is shown. The cutting element assembly 600 includes a cutting element support structure 620 and two cutting elements 601 connected thereto. The cutting element support structure 620 is similar to the previously described cutting element support structure 520 in that it has the same interface for attachment to the main support structure 112 and it has the same 90 degree fan-shaped form factor. Therefore, the cutting element support structure 620 provides the same releasable connection as the cutting element support structure 520, which is achieved by means of fastening bolts 148 entering through holes 613 and fixed to threaded holes 117 of the exterior 116 of the main support structure 112. The cutting element support structure 620 also has through openings 614 distributed between the through holes 613. The purpose of the through openings 614 is the same as that of the through openings 146 of the cutting element support structure 140, namely to allow the wear cover to be fastened. Similar to the previous exemplary embodiment, the periphery 648 seen between a pair of adjacent cutting elements 601 has a radial extension K that is at least 20 mm less than the minimum radial distance T of the pair of adjacent cutting elements 601 (see Fig. 20B ). The advantages of the above characteristics are usually related to Figure 4 The advantages of the first exemplary embodiment are the same as those of the first exemplary embodiment.

[0204] Each cutting element 601 is releasably arranged in the annular engagement portion 611 by means of a geometric locking engagement. The releasable arrangement of the cutting element 601 on the cutting element support structure 620 is Fig.20E As best shown in Fig.20E As shown, the geometric locking engagement is at least partially defined by a protruding structure 660 of the cutting element 601 inserted into an associated recess 662 of the annular engagement portion 611, wherein the protruding structure 660 and the associated recess 662 have complementary shapes. The recess 662 of the annular engagement portion 611 is defined on the side surface of the cutting element support structure 620. The protruding structure 660 forms part of the cutting element retaining structure 603, while the recess 662 forms part of the cutting element support structure 620. The cutting element 601 is releasably attached to the cutting element support structure 620 by means of a fastening bolt 616 (see Fig.20E ). Fig.20E The geometric locking joint shown in is similar to the previous reference Fig.12 A geometric locking engagement is described, although the cutting element support structure, cutting element retaining structure and active cutting element are somewhat different in structure.

[0205] Furthermore, cutting element 601 is structurally different from cutting element 501. Specifically, impact surface 604 is oriented differently from impact surface 504. Impact surface 604 is substantially flat and is disposed obliquely relative to a normal line N of a reference plane RR defined in front of impact surface 604 and is inclined such that a distance L1 between normal line N and impact surface 604 decreases toward flange 36 (see FIG. 2 ). Fig. 20C ).

[0206] For an exemplary embodiment, impact surface 604 is substantially flat. Therefore, the varying distance L1 of cutting element 601 as described above can be further expressed as an angle α defined between impact surface 604 and a normal N to reference plane RR, wherein angle α is defined within a tangential plane TPS of cutting element 601 that is orthogonal to reference plane RR. Fig. 20A and Fig. 20C The angle α can be 1° to 45°, 1° to 35°, 1° to 30°, 1° to 15°, or 2° to 10°, or 3° to 8°, or 4° to 6°, or 5°.

[0207] Cutting element 601 shares some features with cutting element 501 already described. In particular, cutting element 601 also includes an element 605 on one side thereof, which element 605 also includes a surface 606 comprising polycrystalline diamond (PCD). Cutting element 601 is constructed and arranged so that surface 606 forms an angle β between surface 606 facing flange 36 and reference plane RR, wherein angle β is defined in a tangential plane TPS of cutting element 601 orthogonal to reference plane RR. Another similarity is that cutting element 601 is arranged to form an axial protrusion 615 on the side of the rotatable cutting unit. As Fig. 20C As shown, the protrusion 615 has an axial extension X. The axial extension X may be in the range of up to 75 mm, or 5 to 50 mm, or 10 to 40 mm.

[0208] FIG. 21A to FIG. 21C A cutting element assembly 700 according to another exemplary embodiment of the present disclosure is shown. The cutting element assembly 700 is similar to the cutting element assembly 600 already described and is therefore only briefly described herein. Like reference numerals refer to like elements and have been described previously herein. The cutting element assembly 700 includes the aforementioned cutting element support structure 620 and two cutting elements 701. The cutting elements 701 differ from the cutting elements 601 already described in that they do not have dedicated independent elements on the sides of the cutting element retaining structure 703. In addition, the cutting elements 701 do not have angled side surfaces, i.e., the angle β=0° (see, e.g. Fig. 20A and Fig. 21C ). The flange 36 is Fig. 21C Not shown, but with Fig. 20C 600 is located on the right side of cutting element assembly 700 in the same manner as shown in FIG. Therefore, in order to provide a suitable form factor, cutting element retaining structure 703 is slightly thicker than cutting element retaining structure 603. Cutting element 701 is arranged to form an axial protrusion 715 on the side of the rotatable cutting unit. Fig. 21C As shown, the protrusion 715 has an axial extension X. The axial extension X may be in the range of up to 75 mm, or 5 to 50 mm, or 10 to 40 mm. FIG. 21A to FIG. 21C In the exemplary embodiment, the axial extension X is 15 mm. Similar to the previous exemplary embodiment, the periphery 748 seen between a pair of adjacent cutting elements 701 has a radial extension K that is at least 20 mm less than the minimum radial distance T of the pair of adjacent cutting elements 701 (see Fig. 21B ). The advantages of the above characteristics are usually related to Figure 4 The advantages of the first exemplary embodiment are the same as those of the first exemplary embodiment.

[0209] FIG. 22A to FIG. 22CA cutting element assembly 800 according to another exemplary embodiment of the present disclosure is shown. Cutting element assembly 800 is similar to cutting element assembly 700 already described and will therefore only be briefly described here. Like reference numerals refer to like elements and have been described earlier in this document. The main difference between cutting element assembly 800 and cutting element assembly 700 is that the cutting element 801 of cutting element assembly 800 is wider. This allows providing a protrusion 815 with a relatively large axial extension X. For FIG. 16A to FIG. 16C In the exemplary embodiment of the present invention, the axial extension X is 40 mm. The axial extension of this embodiment is X. In order to accommodate the wider form factor, the cutting element retaining structure 803 and the active cutting element 802 are larger than Figures 21A to 21C Similar to the previous exemplary embodiment, the periphery 848 seen between a pair of adjacent cutting elements 801 has a radial extension K that is at least 20 mm less than the minimum radial distance T of the pair of cutting elements 801 (see Fig. 22B ). The advantages of the above characteristics are usually related to Figure 4 The advantages of the first exemplary embodiment are the same as those of the first exemplary embodiment.

[0210] FIG. 23A to FIG. 23C A cutting element assembly 900 according to another exemplary embodiment of the present disclosure is shown. The cutting element assembly 900 is similar to the cutting element assembly 700 already described and is therefore only briefly described herein. Like reference numerals refer to like elements and have been described previously herein. The cutting element assembly 900 includes a cutting element 901 and a cutting element support structure 620 already described. The cutting element 901 differs from the cutting element 701 already described in that the cutting element 901 has a surface 919 facing away from the flange 36, the surface 919 having an extension E3 from the impact surface 604 tangentially toward its rear end 907, wherein the cutting element 901 is constructed and arranged so that the distance L3 between the surface 919 facing away from the flange 36 and the rotating device 190 decreases toward the impact surface 604 over at least a portion of the extension E3.

[0211] As will be readily appreciated by a person skilled in the art, the distance L3 defined between the surface 919 facing away from the rotating device 190 and the rotating device 190 itself must inevitably be defined through the cutting element 901 having said surface 919. In the context of defining the distance L3, "surface" should therefore be interpreted as a mathematical or geometric surface. This is Fig.23A 901 , where distance L3 is marked as a solid line outside cutting element 901 and as a dashed line inside cutting element 901 .

[0212] For the exemplary embodiment, the surface 919 (see FIG. Fig.23C ) is substantially flat. Thus, for cutting element 901, the varying distance L3 as described above can be further represented by an angle γ defined between surface 919 facing away from flange 36 and reference plane RR, wherein angle γ is defined within a tangent plane TPS of cutting element 901 that is orthogonal to reference plane RR. Angle γ can be 1° to 45°, or 1° to 40°, or 1° to 30°, or 5° to 25°, or 5° to 20°, or 5° to 15°, or 8° to 12°, or 10°. Angle γ of cutting element 901, reference plane RR, and tangent plane TPS are Fig.23A and Fig.23C Shown in.

[0213] Similar to the previous exemplary embodiment, the periphery 948 seen between a pair of adjacent cutting elements 901 has a radial extension K that is at least 20 mm less than the minimum radial distance T of the pair of adjacent cutting elements 901 (see Fig. 23B ). The advantages of the above characteristics are usually related to Figure 4 The advantages of the first exemplary embodiment are the same as those of the first exemplary embodiment.

[0214] Fig.24A and Fig. 24B A further exemplary embodiment of the present disclosure is shown. In this case, the drawings show a rotatable cutting unit 1010 comprising a spider 1030 arranged to be mounted on a rotation axis, such as the rotation axis 150, 540 of the exemplary embodiment of the material removal device previously disclosed. The rotatable cutting unit 1010 differs from the previous embodiments in that it comprises a cutting element 1001 having a surface 1019 facing away from the flange 36 and a surface 1006 facing the flange 36, and wherein at least one of the surface 1019 facing away from the flange 36 and the surface 1006 facing the flange comprises a ceramic insert 1090. Arranging the ceramic insert on these surfaces 1006, 1019 will extend the wear life of the cutting element 1001. Similar to the previous exemplary embodiment, the periphery 1048 seen between a pair of adjacent cutting elements 1001 has a radial extension K that is at least 20 mm less than the minimum radial distance T of the pair of adjacent cutting elements 1001 (see Fig.24A ). The advantages of the above characteristics are usually related to Figure 4 The advantages of the first exemplary embodiment are the same as those of the first exemplary embodiment.

[0215] Fig.25The complete assembly of two material removal devices 1100, 1100' according to the present disclosure is shown when arranged on the frame 1200 of the roller crusher 1. The material removal devices 1100 and 1100' are almost identical. The only difference between them is that the rotatable cutting unit 1120 is mounted in an opposite manner, thereby allowing the impact surfaces 1104 of the cutting elements 1101 to face the same direction despite the fact that the material removal devices 1100, 1100' are arranged in a mirror-image manner. The rotatable cutting unit 1110 comprises four cutting element support structures 620 (the same as described with reference to the previous exemplary embodiment), each cutting element support structure carrying two cutting elements 1101, which means that the rotatable cutting unit 1110 comprises eight cutting elements 1101. The cutting element support structures 620 are mounted on the main support structure 112, which in turn is mounted on the shaft member 540 (see also Fig.18C ). The cutting element support structure 620 is covered by the wear-resistant covers 1190a, 1190b, so that Fig.25 The cutting element support structure 620 is not visible in FIG. FIG. 20A to FIG. 23C The wear-resistant covers 1190a and 1190b are similar to those of reference Fig.13 Similar to the previous exemplary embodiment, the periphery 1148 seen between a pair of adjacent cutting elements 1101 has a radial extension K that is at least 20 mm less than the minimum radial distance T of the pair of adjacent cutting elements 1101 (see FIG. Fig.25 ). The advantages of the above characteristics are usually related to Figure 4 The advantages of the first exemplary embodiment are the same as those of the first exemplary embodiment.

[0216] The cutting element 1102 is similar to the previous reference Fig.10 The disclosed cutting element 220 is therefore only briefly described herein. The active cutting element 1102 has an impact surface 1104 having a front portion 1104a and a rear portion 1104b connected to each other. The front portion 1104a is arranged upstream of the rear portion 1104b so that the front portion 1104a will first encounter the material to be removed from the roller 3. When the material removal device 1100 is arranged on the roller crusher 1, the front portion 1104a will be arranged closer to the flange 36 than the rear portion 1104b. This can be advantageous because it allows a very strong impact force to be generated by the front portion 1104a in a local area of ​​the accumulated material on the roller 3 with the flange 36, thereby increasing the possibility of breaking a larger portion of the material. The rear portion 1104b can then intervene and help further remove material from the roller 3 and / or transport the already removed material away from the flange 36. The front portion 1104a includes polycrystalline diamond (PCD). The rear portion 1104b may also include polycrystalline diamond (PCD).

[0217] Fig.25 The drive unit 195 and the transmission system 180 are also shown in a more realistic manner than in the previous schematic diagrams.

[0218] Those skilled in the art recognize that the present disclosure is by no means limited to the preferred embodiments described above. On the contrary, within the scope of the appended claims, many modifications and variations are possible. For example, the exemplary embodiments of the rotatable cutting unit given herein constitute a relatively complex assembly of multiple elements. However, it is important to remember that the rotatable cutting unit of the present disclosure should not be interpreted as being limited to such an assembly. It is also conceivable to provide a rotatable cutting unit made of a single material, in which the claimed features are formed in one piece. For example, the rotatable cutting unit can be formed by a single steel element and cut to produce a cutting element as its radially outward protrusion. Each cutting element can be cut to provide an impact surface of a suitable shape. Although not explicitly shown in the drawings, it is obvious to those skilled in the art that the design is based on the present disclosure and the common knowledge in the art. In addition, by studying the drawings, the disclosure and the appended claims, those skilled in the art can understand and implement variations of the disclosed embodiments when practicing the claims.

[0219] Example

[0220] Embodiment 1. A roller crusher having two substantially parallel rollers arranged to rotate in opposite directions and separated by a gap, each roller having two ends, the roller crusher comprising:

[0221] a flange, attached to one end of one of the rollers,

[0222] The flange extends in the radial direction of the one roller, and

[0223] said flange having an extension (H) beyond the envelope surface of said one roller,

[0224] The roller crusher further comprises a material removal device, wherein the material removal device comprises:

[0225] a rotatable cutting unit having a plurality of cutting elements arranged tangentially around the rotatable cutting unit at respective radial distances from an axis of rotation of the rotatable cutting unit; and

[0226] a rotating device arranged to rotate the rotatable cutting unit,

[0227] wherein the rotatable cutting unit is arranged at one end of a roller with a flange so as to at least partially allow the material accumulated on the envelope surface of the roller at the end portion adjacent to the flange and / or on the flange to be cut off when the rotating device rotates it,

[0228] wherein each cutting element of the plurality of cutting elements has an impact surface arranged to face the material to be removed, and

[0229] Each of the impact surfaces comprises polycrystalline diamond (PCD).

[0230] Embodiment 2. A roll crusher according to embodiment 1, wherein the cutting element further comprises a wear-resistant material, and the polycrystalline diamond (PCD) is at least partially embedded in the wear-resistant material.

[0231] Embodiment 3. The roller crusher according to embodiment 2, wherein the wear-resistant material is selected from one of a ceramic material, a metal-ceramic composite material and a metal matrix composite material.

[0232] Embodiment 4. A roll crusher according to any one of embodiments 1 to 3, wherein the impact surface is substantially flat and arranged transversely to the tangential movement direction of the cutting element.

[0233] Embodiment 5. A roller crusher according to any one of embodiments 1 to 4, wherein the rotatable cutting unit is arranged at a first end of the material removal device, and the rotating device is arranged at an opposite second end of the material removal device, and wherein the rotatable cutting unit extends in a reference plane orthogonal to the rotation axis.

[0234] Embodiment 6. A roller crusher according to embodiment 5, wherein each impact surface of the plurality of cutting elements is substantially flat and is arranged to be inclined relative to a normal line of the reference plane defined in front of the impact surface, and is inclined so that the distance between the normal line and the impact surface decreases toward the flange.

[0235] Embodiment 7. A roller crusher according to any one of embodiments 1 to 6, wherein the impact surface has a front portion and a rear portion connected to each other, wherein the front portion is arranged upstream of the rear portion from the tangential movement direction of the cutting element, and the front portion is arranged to be closer to the flange than the rear portion.

[0236] Embodiment 8. A roller crusher according to embodiment 7, wherein the rear portion is shaped to convey the excised material in a direction away from the flange.

[0237] Embodiment 9. A roll crusher according to embodiment 8, wherein the rear portion is substantially flat and forms an oblique angle relative to the tangential movement direction of the cutting element.

[0238] Embodiment 10. The roll crusher of embodiment 8, wherein the rear portion is curved inwardly to form a bowl shape.

[0239] Embodiment 11. A roller crusher according to any one of embodiments 5 to 10, wherein each of the cutting elements has a flange-facing surface, the flange-facing surface having an extension tangentially from its impact surface toward its rear end, wherein the cutting element is constructed and arranged so that the distance between the flange-facing surface and the rotating device decreases toward the impact surface over at least a portion of the extension.

[0240] Embodiment 12. The roll crusher of any one of Embodiments 1 to 11, wherein each cutting element has a flange-facing surface comprising polycrystalline diamond (PCD).

[0241] Embodiment 13. A roller crusher according to any one of embodiments 5 to 12, wherein each of the plurality of cutting elements has a surface facing away from the flange, the surface facing away from the flange having an extension tangentially from the impact surface toward its rear end, wherein the cutting element is constructed and arranged so that the distance between the surface facing away from the flange and the rotating device decreases toward the impact surface over at least a portion of the extension.

[0242] Embodiment 14. The roll crusher of any one of embodiments 1 to 13, wherein the plurality of cutting elements are arranged to form an axial protrusion on one or both sides of the rotatable cutting unit.

[0243] Embodiment 15. A roller crusher according to embodiment 14, wherein the axial protrusion has an axial extension in the range of at most 75 mm, or 5 to 50 mm, or 10 to 40 mm.

[0244] Embodiment 16. A roller crusher according to any one of embodiments 1 to 15, wherein the rotatable cutting unit extends in a reference plane orthogonal to the rotation axis of the rotatable cutting unit, wherein each of the plurality of cutting elements extends in the reference plane along the cutting element axis toward the impact surface, and wherein the cutting element axis forms a first acute angle with a radial axis of the rotatable cutting unit along a reference rotation direction, and the radial axis intersects the cutting element.

[0245] Embodiment 17. The roll crusher of Embodiment 16, wherein each impact surface of the plurality of cutting elements extends in a plane having a normal that forms an acute angle with the cutting element axis along the reference direction.

[0246] Embodiment 18. A roller crusher according to any one of Embodiments 1 to 17, wherein each of the plurality of cutting elements has a surface facing away from the flange and a surface facing the flange, and wherein at least one of the surface facing away from the flange and the surface facing the flange includes a ceramic insert.

[0247] Embodiment 19. A roll crusher according to any one of embodiments 1 to 18, wherein each cutting element of the plurality of cutting elements comprises a cutting element retaining structure and an active cutting element attached thereto, wherein the active cutting element has the impact surface.

[0248] Embodiment 20. A roller crusher according to any one of embodiments 1 to 19, wherein the rotatable cutting unit has an annular engagement portion, and wherein each cutting element of the plurality of cutting elements is releasably arranged to the annular engagement portion.

[0249] Embodiment 21. A roller crusher according to embodiment 20, wherein the rotatable cutting unit further comprises a main support structure and at least two cutting element support structures, wherein the at least two cutting element support structures are releasably arranged relative to the main support structure and are shaped into a plurality of circular sectors that together form a circular ring, and the circular ring has the annular joint portion.

[0250] Embodiment 22. A roller crusher according to embodiment 20 or 21, wherein each cutting element of the plurality of cutting elements is releasably arranged in the annular engagement portion by a geometric locking engagement.

[0251] Embodiment 23. A roller crusher according to embodiment 22, wherein the geometric locking engagement is at least partially defined by a protruding structure of the cutting element being inserted into an associated recess of the annular engagement portion, wherein the protruding structure and the associated recess have complementary shapes.

[0252] Embodiment 24. A roller crusher according to embodiment 23, wherein the associated recesses of the annular engagement portion are defined on a side surface thereof.

[0253] Embodiment 25. A roller crusher according to embodiment 23 or 24, wherein the plurality of cutting elements each comprises a cutting element retaining structure and an active cutting element attached thereto, wherein the active cutting element has the impact surface, and wherein the protruding structure forms part of the cutting element retaining structure.

[0254] Embodiment 26. The roll crusher of any one of embodiments 1 to 25, further comprising a wear-resistant cover constructed and arranged to protect at least a portion of the rotatable cutting unit.

[0255] Embodiment 27. A roller crusher according to any one of embodiments 1 to 26, wherein the periphery of the rotatable cutting unit has a radial extension as seen between a pair of adjacent cutting elements of the plurality of cutting elements, and the radial extension is at least 20 mm smaller than the minimum radial distance of the pair of adjacent cutting elements.

[0256] Embodiment 28. A method for operating a roller crusher according to any one of Embodiments 1 to 27, wherein the method comprises at least a step of at least partially removing material accumulated on the envelope surface of the roller at the end adjacent to the flange and / or on the flange by means of the material removal device.

Claims

1. A roller crusher having two substantially parallel rollers arranged to rotate in opposite directions and separated by a gap, each roller having two ends, the roller crusher comprising: a flange, attached to one end of one of the rollers, The flange extends in the radial direction of the one roller, and said flange having an extension (H) beyond the envelope surface of said one roller, The roller crusher further comprises a material removal device, wherein the material removal device comprises: a rotatable cutting unit having a plurality of cutting elements arranged tangentially around the rotatable cutting unit at respective radial distances from an axis of rotation of the rotatable cutting unit; and a rotating device arranged to rotate the rotatable cutting unit, wherein the rotatable cutting unit is arranged at one end of a roller with a flange so as to at least partially allow the material accumulated on the envelope surface of the roller at the end portion adjacent to the flange and / or on the flange to be cut off when the rotating device rotates it, wherein each cutting element of the plurality of cutting elements has an impact surface arranged to face the material to be removed, and Each of the impact surfaces comprises polycrystalline diamond (PCD).

2. The roll crusher of claim 1, wherein the cutting element further comprises a wear resistant material, the polycrystalline diamond (PCD) being at least partially embedded in the wear resistant material.

3. The roll crusher according to claim 2, wherein the wear-resistant material is selected from one of a ceramic material, a metal-ceramic composite material and a metal-based composite material.

4. A roller crusher according to any one of claims 1 to 3, wherein the impact surface is substantially flat and is arranged transversely to the tangential movement direction of the cutting element.

5. A roller crusher according to any one of claims 1 to 4, wherein the rotatable cutting unit is arranged at a first end of the material removal device and the rotating device is arranged at an opposite second end of the material removal device, and wherein the rotatable cutting unit extends in a reference plane orthogonal to the rotation axis.

6. A roller crusher according to claim 5, wherein each impact surface of the plurality of cutting elements is substantially flat and is arranged to be inclined relative to a normal line of the reference plane defined in front of the impact surface, and is inclined so that the distance between the normal line and the impact surface decreases towards the flange.

7. A roller crusher according to any one of claims 1 to 6, wherein the impact surface has a front part and a rear part connected to each other, wherein the front part is arranged upstream of the rear part as seen in the tangential movement direction of the cutting element, and the front part is arranged closer to the flange than the rear part.

8. A roller crusher according to claim 7, wherein the rear portion is shaped to convey the cut material in a direction away from the flange.

9. A roll crusher according to claim 8, wherein the rear portion is substantially flat and forms an oblique angle with respect to the direction of tangential movement of the cutting element.

10. The roll crusher of claim 8, wherein the rear portion is bent inwardly to form a bowl shape.

11. A roller crusher according to any one of claims 5 to 10, wherein each of the cutting elements has a flange facing surface having an extension tangentially from its impact surface towards its rear end, wherein the cutting elements are constructed and arranged so that the distance between the flange facing surface and the rotating device decreases towards the impact surface over at least a part of the extension.

12. A roll crusher according to any one of claims 1 to 11, wherein each cutting element has a flange facing surface comprising polycrystalline diamond (PCD).

13. A roller crusher according to any one of claims 5 to 12, wherein each of the plurality of cutting elements has a surface facing away from the flange, the surface facing away from the flange having an extension tangentially from the impact surface towards its rear end, wherein the cutting element is constructed and arranged so that the distance between the surface facing away from the flange and the rotating device decreases towards the impact surface over at least a portion of the extension.

14. The roller crusher according to any one of claims 1 to 13, wherein the plurality of cutting elements are arranged to form an axial protrusion on one or both sides of the rotatable cutting unit.

15. A roller crusher according to claim 14, wherein the axial protrusions have an axial extension in the range of at most 75 mm, or 5 to 50 mm, or 10 to 40 mm.

16. A roller crusher according to any one of claims 1 to 15, wherein the rotatable cutting unit extends in a reference plane orthogonal to the rotation axis of the rotatable cutting unit, wherein each of the plurality of cutting elements extends in the reference plane along a cutting element axis toward the impact surface, and wherein the cutting element axis forms a first acute angle with a radial axis of the rotatable cutting unit along a reference rotation direction, the radial axis intersecting the cutting element.

17. The roll crusher of claim 16, wherein each impact surface of the plurality of cutting elements extends in a plane having a normal that forms an acute angle with the cutting element axis along the reference direction.

18. A roll crusher according to any one of claims 1 to 17, wherein each of the plurality of cutting elements has a surface facing away from the flange and a surface facing the flange, and wherein at least one of the surface facing away from the flange and the surface facing the flange comprises a ceramic insert.

19. A roll crusher according to any one of claims 1 to 18, wherein each cutting element of the plurality of cutting elements comprises a cutting element retaining structure and an active cutting element attached thereto, wherein the active cutting element has the impact surface.

20. A roller crusher according to any one of claims 1 to 19, wherein the rotatable cutting unit has an annular engagement portion, and wherein each cutting element of the plurality of cutting elements is releasably arranged to the annular engagement portion.

21. A roller crusher according to claim 20, wherein the rotatable cutting unit further comprises a main support structure and at least two cutting element support structures, wherein the at least two cutting element support structures are releasably arranged relative to the main support structure and are shaped as a plurality of circular ring sectors that together form a circular ring, and the circular ring has the annular engagement portion.

22. A roller crusher according to claim 20 or 21, wherein each cutting element of the plurality of cutting elements is releasably arranged in the annular engagement portion by means of a geometric locking engagement.

23. A roller crusher according to claim 22, wherein the geometric locking engagement is at least partly defined by a protruding structure of the cutting element being inserted into an associated recess of the annular engagement portion, wherein the protruding structure and the associated recess have complementary shapes.

24. A roller crusher according to claim 23, wherein the associated recesses of the annular engagement portion are defined on a side surface thereof.

25. A roller crusher according to claim 23 or 24, wherein each cutting element of the plurality of cutting elements comprises a cutting element retaining structure and an active cutting element attached thereto, wherein the active cutting element has the impact surface, and wherein the protruding structure forms part of the cutting element retaining structure.

26. A roll crusher according to any one of claims 1 to 25, further comprising a wear resistant cover constructed and arranged to protect at least a portion of the rotatable cutting unit.

27. A roller crusher according to any one of claims 1 to 26, wherein the periphery of the rotatable cutting unit, seen between a pair of adjacent cutting elements of the plurality of cutting elements, has a radial extension which is at least 20 mm less than a minimum radial distance of the pair of adjacent cutting elements.

28. Method for operating a roller crusher according to any one of claims 1 to 27, wherein the method comprises at least the step of at least partially removing material accumulated on the envelope surface of the roller at the end portion adjacent to the flange and / or on the flange by means of a material removal device.

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