Comminuting device for comminuting cut material particles having a curved cutting edge profile

Abstract

A comminution device for comminuting material particles, in particular grain or fiber particles, is proposed, comprising at least two counter-clockwise driven comminution rollers, each having a longitudinal axis (L) and an alternating sequence of circumferential grooves and ribs on its respective outer surface, the flanks of which extend at an angle ≠ 90° to the longitudinal axes of the rollers, wherein at least one engagement pair consisting of a circumferential rib of one roller and a circumferential groove of the other roller is formed between the comminution rollers, such that a comminution gap is formed between two adjacent flanks, the device being characterized in that the flanks are provided with a cutting edge profile (12) having a plurality of cutting edges (13) and grooves (14), the cutting edges (13) of which have a curved profile along a curved line (K).in particular a helix or a conical spiral extending from the longitudinal axis (L) of the roller in question along a flank surface to a circumferential edge (15) of the crushing roller in question.

Description

[0001] The invention relates to a comminution device for comminuting material particles, in particular grain or fiber particles. The device comprises at least two counter-rotating comminution rollers, each having a longitudinal axis and an alternating sequence of circumferential grooves and ribs on its respective outer surface, the flanks of which extend at an angle ≠ 90°, i.e., obliquely, to the longitudinal axes of the rollers. At least one engagement pair is formed between the comminution rollers, consisting of a circumferential rib of one roller and a circumferential groove of the other roller. This creates a comminution gap between two adjacent flanks, which is sometimes also referred to as a parallel gap.

[0002] Such a generic device is known from European patent EP 1 600 214 B1. In the previously known device, the flanks each additionally have a threaded profile, which ensures an increased shear effect between the flanks.

[0003] The invention is based on the objective of further developing a comminution device of the aforementioned type in such a way as to achieve a further improved comminution result. At the same time, the manufacture of the comminution device or its essential components, i.e., the comminution rollers, is to be simplified and thus made more cost-effective. The comminution device should be specifically variable depending on the raw material and the required comminution result, and homogeneous cutting conditions should be present or achievable throughout the grinding gap to ensure a homogeneous comminution result (i.e., low particle size variation).

[0004] This problem is solved according to the invention by a comminution device for comminuting material particles, in particular grain or fiber particles, with at least two counter-rotating comminution rollers, each having a longitudinal axis and an alternating sequence of circumferential grooves and ribs on its respective outer surface, i.e., grooves and ribs that extend circumferentially and thus run around the comminution rollers. The flanks of the circumferential grooves and ribs extend at an angle ≠ 90° (i.e., obliquely) to the longitudinal axes of the rollers. At least one engagement pair is formed between the comminution rollers, consisting of a circumferential rib of one roller and a circumferential groove of the other roller, so that a comminution gap or parallel gap is formed between two adjacent flanks.The flanks are provided with a cutting edge profile comprising multiple cutting edges and grooves, the cutting edges of which have a curved path along a curved line, in particular a helix or a conical spiral, extending from the longitudinal axis of the respective roller along a flank surface to a circumferential edge of the respective shredding roller. The cutting edges therefore do not run exactly radially to the axis of rotation of the shredding rollers, but rather have a specific curved path (along the aforementioned – imaginary – curved line, helix, or conical spiral).

[0005] The applicant has discovered that particularly good comminution results can be achieved with such a cutting edge profile, while the manufacturing process has been simplified compared to the previously known device. Furthermore, by slightly varying certain parameters of the cutting edge profile, variants of the device according to the invention can be easily created that are particularly well suited for specific comminution tasks.

[0006] Particularly preferred are the flanks provided with a cutting edge profile comprising a plurality of cutting edges and grooves, the cutting edges of which have a curved path along a three-dimensionally curved line, i.e., a line that is curved in all three spatial directions of three-dimensional space. In particular, this is again a helix or a conical spiral. The three-dimensionally curved line extends from the longitudinal axis of the respective roller along a flank surface to a circumferential edge of the respective shredding roller. Thus, the cutting edges do not run exactly radially to the axis of rotation of the shredding rollers or in an arc-shaped pattern in a plane inclined to the axis of rotation, but rather they have a three-dimensionally curved path that follows a cylindrical or conical surface of the rollers as closely as possible.

[0007] This three-dimensionally curved profile is particularly advantageous for the properties of the cutting edges in the comminution device, and these can be selectively varied along the three-dimensional curve to achieve a favorable comminution effect. In particular, the profile along the cylindrical / conical surface allows for a targeted, independent variation of the cutting edge height and the remaining unprocessed surface area, i.e., an unprocessed surface area of ​​the flanks, which acts as a crushing surface in the comminution process, while simultaneously maintaining a fixed angular position of the cutting edge relative to a clearance surface opposite the cutting edge (where the cutting edge and clearance surface together define / limit a respective cutting groove) and only minimal variation of the cutting edge angle, which is particularly advantageous for manufacturing the cutting edges.The cutting edge angle is an angle relative to a normal direction N to the flank surface (see below). The cutting edge and the clearance face preferably form an angle of 90 degrees between them.

[0008] The following properties of the three-dimensionally curved line are advantageous: The curvature of the line varies (in particular linearly) depending on the height of the conical (top) surface in the z-direction (height direction) and in the radius direction. This height is determined along the axis of the cone or truncated cone that forms the base body of the shredding rollers or shredding discs and describes its greatest extent in this direction. The angle of inclination λ, i.e., the angle between a tangent to the curved line and a plane containing the axis of rotation (i.e., the longitudinal axis of the rollers), preferably also varies along the curved line(s). The curved lines are preferably rotationally / mirror-symmetric with respect to the axis of rotation.

[0009] Such a three-dimensional curved profile along the surface can be achieved – as already mentioned – for example by forming the cutting edges according to a helix or a conical spiral.

[0010] EP 1 600 214 shows so-called threaded sections on the flank surfaces, which, however, do not serve as cutting edges but rather are intended to achieve a shearing effect. These threaded sections run circumferentially several times with respect to the longitudinal axis of the roller. Cutting, on the other hand, is carried out according to claims 7 to 11 of that patent via straight cutting surfaces along additional drive edges, which are purely radially oriented.

[0011] According to the invention, the flanks are provided with a cutting edge profile comprising a plurality of cutting edges and grooves, the cutting edges of which have a curved path along a curved line, in particular a helix or a conical spiral, extending from the longitudinal axis of the respective roller along a flank surface to a circumferential edge of the respective shredding roller. The present invention thus improves upon the previously known radial drive edges and eliminates the need for additional threads. In contrast to the aforementioned previously known threads, the cutting edges do not complete a full circumferential rotation with respect to the longitudinal axis of the roller, but each extend only over a (small) partial circumferential area.

[0012] The following embodiments and further developments of the comminution device (or, in short, the device) according to the invention have proven to be particularly useful and effective in practice: One further development of the comminution device according to the invention is characterized in that the cutting groove depth along the curved path is essentially constant. Similarly, the cutting edge height along the curved path can also be essentially constant.

[0013] The term "essentially constant" here and in the following refers to a deviation that lies within usual tolerance limits.

[0014] According to the applicant, this allows for particularly good and homogeneous comminution results.

[0015] Another embodiment of the comminution device according to the invention is characterized in that the curvature of the line relative to a direction of rotation of the respective comminution roller is convex, so that the circumferential ends of the cutting edges have a so-called lead-in. By selecting the curvature, the strength or degree of the lead-in can be specifically adjusted.

[0016] Leading edge therefore means that the circumferential ends of the cutting edges are located further "forward" in the direction of rotation of the respective shredding roller than those ends of the cutting edges that are closer to the axis of rotation.

[0017] The specific selection of the pre-feed allows for targeted influence on the comminution result. A pre-feed ensures good material feeding.

[0018] Yet another embodiment of the comminution device according to the invention is characterized in that the pre-run temperature is between 0 degrees and 30 degrees, preferably between 0 degrees and 15 degrees, most preferably between 0 degrees and 7 degrees.

[0019] The applicant has recognized that the best comminution results in terms of achievable throughput can be achieved in these angular ranges for the pre-run, e.g. in the field of feed comminution or comparable applications in the chemical, recycling and food industries.

[0020] A further development of the comminution device according to the invention is characterized in that a curvature of the line with respect to a direction of rotation of the respective comminution roller is concave, so that the circumferential ends of the cutting edges have a trail.

[0021] Therefore, "overrun" means that the circumferential ends of the cutting edges are located further "back" in the direction of rotation of the respective shredding roller than those ends of the cutting edges that are closer to the axis of rotation.

[0022] The specific selection of the finishing stage also allows for targeted influence on the grinding result. In particular, a finishing stage ensures intensive processing and a fine grinding result, e.g., for fine grinding in the animal feed industry.

[0023] A further development of the comminution device according to the invention is characterized in that the after-run is between 0 degrees and 30 degrees, preferably between 0 degrees and 15 degrees, most preferably between 0 degrees and 9 degrees.

[0024] The applicant has recognized that the best comminution results in terms of processing intensity can be achieved in these angular ranges for the trailing section.

[0025] A further development of the comminution device according to the invention is characterized in that the cutting edges have a variable cutting edge angle along their course along the curved line relative to a normal direction to the flank surface.

[0026] Such a variable cutting edge angle has proven advantageous with regard to both the comminution result and the manufacturing effort. Preferably, in this way, a relatively small amount of the unmachined flank surface can be kept constant with a constant tooth height (i.e., constant cutting edge height) while requiring relatively little manufacturing effort.

[0027] A further development of the comminution device according to the invention is characterized in that the cutting edge angle is between 0 degrees and 65 degrees, preferably between 5 degrees and 25 degrees, most preferably between 8 degrees and 19.5 degrees.

[0028] The applicant has recognized that the best shredding results can be achieved in these angle ranges for the cutting edge angle.

[0029] A further development of the comminution device according to the invention is characterized in that an unprocessed surface fraction of the flanks - i.e., the flank fraction that does not function as a cutting edge or cutting groove - is essentially constant over an entire course from an inner edge of the cutting edge profile facing the respective longitudinal axis (axis of rotation) of the rollers to the circumferential edge, preferably minimal, most preferably approximately zero.

[0030] This surface area, which acts as a so-called squashing area in the comminution process, has a particularly beneficial effect when it is constant and preferably as small as possible for a homogeneous grinding result. In this context, the specification "approximately zero" means that the squashing area is chosen to be as small as is (still) permissible from a stability and manufacturing perspective.

[0031] A further development of the comminution device according to the invention is characterized in that the surface area is between 5% and 50%, preferably between 10% and 25%.

[0032] The applicant has recognized that the best comminution results can be achieved in these value ranges for the surface area fraction.

[0033] Another embodiment of the comminution device according to the invention is characterized in that the height of the cutting edges or the depth of the cutting grooves with respect to the flank surface is between 0.1 mm and 5 mm, preferably between 0.25 mm and 2.5 mm, most preferably between 0.5 mm and 1.5 mm.

[0034] The applicant also recognized in her considerations that the best comminution results could be achieved in these value ranges for the height of the cutting edges or the depth of the cutting grooves.

[0035] If all the geometric parameters of the device or cutting edge profile described above are adjusted together in a corresponding further development of the device, as indicated, the device can be significantly improved because the geometric parameters relevant to the comminution process (i.e., cutting angle, tooth height, proportion of unprocessed area, and, to a limited extent, lead and trail) are as uniform as possible at all points on the flanks and can be adjusted precisely and independently of the disc size. For example, the lead or trail can be varied without changing the tooth height (i.e., the height of the cutting edges) or the groove depth (i.e., the depth of the cutting grooves) along a cutting edge, which was consistently the case with previously known profiles. The preferred helical geometry offers a favorable solution for this.

[0036] However, the invention is not fundamentally limited to defining all the aforementioned geometric dimensions together as described above. Even the targeted selection of one or more of these dimensions can provide a corresponding advantage over the prior art.

[0037] Yet another embodiment of the comminution device according to the invention is characterized in that the comminution rollers are arranged horizontally and a feed opening for the material particles is arranged vertically above the comminution rollers in the area of ​​the engagement pairing.

[0038] In this way, the natural effect of gravity on the material being cut can be used to easily feed it to the device in the desired area.

[0039] A further development of the comminution device according to the invention is characterized in that the alternating sequence of circumferential grooves and circumferential ribs is formed by comminution discs arranged (detachably) on a central shaft.

[0040] This is advantageous for maintenance reasons. Furthermore, it allows for the modular assembly of shredding rollers of virtually any length.

[0041] A particularly advantageous embodiment of the comminution device according to the invention is characterized in that the comminution discs, in a longitudinal section, correspond to a double cone with diverging, truncated tips. Alternatively, the embodiment can also be described as a double truncated cone, i.e., as an arrangement of two truncated cones with their respective top surfaces separated from each other and connected to each other at their respective bases, wherein the cutting edge profile is located on a lateral surface of the cones (truncated cones).

[0042] A further advantageous embodiment of the comminution device according to the invention is characterized in that the cutting edge profile is produced by machining the comminution discs, in particular by milling.

[0043] This is an easily manageable process that allows the cutting edge profiles described above to be produced well and inexpensively.

[0044] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the drawing. Figure 1 shows a comminution device according to the invention in a cross-section transverse to the longitudinal axis of the rollers; Figure 2 shows a horizontal section through a comminution device according to the invention in the area of ​​the comminution rollers; Figure 3 shows a top view of a shredding disc and a section through the corresponding cutting edge profile, particularly for the purpose of explaining the chosen nomenclature; Figure 4 shows three possible designs of a shredding disc, each in a top view; Figure 5shows two possible designs of a shredding disc, each in a top view and in section as a corresponding detail enlargement; Figure 6 shows two further possible designs of a shredding disc, each in a top view and in section as a corresponding detail enlargement; Figure 7 shows two possible designs of a shredding disc, each in a top view and in section as a corresponding detail enlargement; Figure 8 shows two further possible designs of a shredding disc, each in a top view; and Figure 9 shows further advantageous geometric properties of the cutting edges of a shredding disc.

[0045] In all figures, the same reference symbols denote identical or at least equivalent elements.

[0046] In Figure 1Figure 1 shows a cross-section of a comminution device 1 according to the invention. The device 1 comprises two comminution rollers, designated by reference numerals 2 and 3. They rotate in opposite directions or are driven accordingly, as symbolized by arrows P and P'. The viewing direction in Figure 1 is parallel to the longitudinal axes of the shredding rollers 2, 3. In a region B, the shredding rollers 2, 3 are in (effective) engagement with each other, as will be shown below based on the Figure 2 This will be discussed in more detail below. The process involves shredding material that is fed from above, in the direction of gravity, through a feed opening 4 for material particles 5 into area B, as indicated by arrow PS. The shredded material 6 exits the device 1 downwards, as indicated by arrow PZ.

[0047] Figure 2 shows that area B of device 1 Figure 1, in which the shredding rollers 2, 3 are engaged with each other. In the Figure 2 is a horizontal cut perpendicular to the feed direction of the material being cut (direction of the arrow PS in Figure 1 ) shown, and the longitudinal axes of the crushing rollers 2, 3 are labelled L2 and L3 respectively.

[0048] How to Figure 2The shredding rollers 2, 3 are each formed with shredding discs 8 preferably detachably arranged on a central shaft 7, of which only a few are explicitly designated for the sake of clarity. The shredding discs 8 taper to a point at their outer edge radially relative to the shaft 7, creating an alternating sequence of circumferential grooves 9 and circumferential ribs 10 for each of the shredding rollers 2, 3. In other words, each shredding roller 2, 3 has an alternating sequence of circumferential grooves 9 and circumferential ribs 10 on its respective outer surface, the flanks of which (designated as 9a and 9b for a groove 9 and as 10a and 10b for a rib 10) extend at an angle α ≠ 90° to the roller longitudinal axes L2, L3. The shredding discs 8 are positioned between the two shredding rollers 2, 3 by half a disc thickness D (i.e.arranged offset by a dimension D / 2) so that a series of engagement pairs is formed between the comminution rollers 2, 3, each consisting of a circumferential web 10 of one roller and each circumferential groove 9 of the other roller, wherein a comminution gap 11 (also referred to as a parallel gap) is always formed between two adjacent flanks 9a, 10a or 9b, 10b.

[0049] How to Figure 2The shredding discs 8 are designed in a longitudinal section in the form of a double cone with diverging, truncated tips (and a central opening for the shaft 7). Alternatively, it can be stated that the shredding discs 8 are each designed as a double truncated cone made up of two truncated cones with widely separated top surfaces (and a central opening for the shaft 7), which are connected to each other at their respective bases. Adjacent shredding discs 8 on the shaft 7 are (detachably) connected to each other via their respective top surfaces 8a.

[0050] Such a design is fundamentally known from the aforementioned EP 1 600 214 A1, to which reference is made in this respect. There, the circumferential webs or...

[0051] Circumferential grooves are sometimes referred to linguistically as radial webs and grooves, which, however, is of no constructive significance.

[0052] The cutting edge profile already mentioned, which will now be explained in more detail, is formed on a lateral surface of the cones (or truncated cones) of the shredding discs 8. Preferably, all shredding discs 8 arranged on the shaft 7 are identical, although there are some applications where the outer discs may have a different profile. It also occurs that the two shafts 7 of a device 1 (see Figure 1) are arranged in a single, identical configuration. Figure 1 and 2 ) are equipped with shredding discs 8 of different profiles. For example, a shaft 7 can be fitted with almost smooth shredding discs 8.

[0053] The lateral surfaces of the cones (-truncated cones) of the shredding discs 8 according to Figure 2 , i.e., flanks 9a, 9b and 10a, 10b are - as e.g. in the Figure 3shown - with a cutting edge profile 12 having a plurality of cutting edges 13 and grooves 14. The cutting edges 13 (and correspondingly also the cutting grooves 14) do not run exactly radially to the axis of rotation of the shredding rollers (in Figure 3 (designated with a cross and the generic reference symbol L), but take a curved course along a curved line K (in Figure 3 (shown as a dashed line), which corresponds to a helix or – due to the special conical geometry of the shredding discs 8 – mathematically more accurately to a conical spiral. The line K runs from the respective longitudinal axis L of the roller along the surface of one of the flanks 9a, 9b or 10a, 10b (see Figure 1). Figure 2 ) to a circumferential edge 15 of the relevant crushing roller 2, 3 (cf. Figure 2 ) or the shredding disc 8.

[0054] In the central, white area 8a of the shredding disc 8 in Figure 3This refers to the (flat) area with which the shredding disc 8 rests against an adjacent shredding disc 8, cf. Figure 2 (also referred to there as the top surface).

[0055] Reference symbol R denotes the radius of the shredding disc 8; the reference symbol x stands for a lead-in, which (assuming the direction of rotation of the shredding disc 8 according to Figure 3 clockwise) results because of the (relative to the stated direction of rotation; see arrow P in the Figures 3 to 8The convex curvature of the line K, or the cutting edges 13 / cutting grooves 14, causes the circumferential ends 16 of the cutting edges 13 to lead the inner ends 17 of the same cutting edges 13 (rotationally) angularly in the direction of the axis of rotation L. This is explicitly shown and labeled at only one point. With an opposite, concave curvature of the line K, a corresponding lag results (the sign of x is then negative). The magnitude of x depends on the degree of curvature of the line K. The angular lag can be, in particular, between 0 degrees and 30 degrees, preferably between 0 degrees and 15 degrees, and most preferably between 0 degrees and 7 degrees. The same applies to the lag. The angular lag can be, in particular, between 0 degrees and 30 degrees, preferably between 0 degrees and 15 degrees, and most preferably between 0 degrees and 9 degrees.

[0056] The enlarged section in the lower part of Figure 3shows a section through the cutting edge profile 12 approximately along the dashed line in the upper part of the Figure 3 .

[0057] The indicated angle β is the so-called cutting edge angle, wherein the individual cutting edges 13 preferably have a variable cutting edge angle β along their course according to the curved line K, which is defined with respect to a normal direction N to the flank surface (surface of the flanks 9a, 9b; 10a, 10b in Figure 2 ) or the surface 18 of the comminution disc 8 in the area of ​​the cutting grooves 14. The cutting edge angle β can be, in particular, between 0 degrees and 65 degrees, preferably between 5 degrees and 25 degrees, most preferably between 8 degrees and 19.5 degrees. Its variation along the line K is preferably between 3 degrees and 6 degrees.

[0058] Reference symbol t denotes a height of the cutting edges 13 or - alternatively - a depth of the cutting grooves 14 with respect to the flank surface (surface of the flanks 9a, 9b; 10a, 10b in Figure 2 or the surface 18 of the shredding disc 8 in the area of ​​the cutting grooves 14). It can be between 0.1 mm and 5 mm, preferably between 0.25 mm and 2.5 mm, most preferably between 0.5 mm and 1.5 mm, and in particular be variable along a cutting edge 13 or cutting groove 14. However, it is particularly preferred to keep the height t of the cutting edges 13 exactly constant, which is not possible with non-radial profiles with straight cutting edges.

[0059] Reference numeral 19 in Figure 3 This represents an unprocessed surface area of ​​the flanks. Specifically, it refers to the surface area of ​​flanks 9a, 9b; 10a, 10b in Figure 2or that part of the surface of the shredding disc 8 in the area of ​​the cutting edge profile 12 which remained unchanged during the formation of the cutting edges 13 or cutting grooves 14 (e.g., by milling or another, preferably machining, process). The unprocessed surface area 19 can be essentially constant (e.g., constant width) over its entire length from one of the inner edges of the cutting edge profile 12 facing the respective longitudinal axis of the roller (axis of rotation L) to the circumferential edge 15 and is preferably minimal in size, most preferably approximately zero.

[0060] Other embodiments include the fact that the aforementioned surface area 19 is between 5% and 50%, preferably between 10% and 25%, preferably in each case based on the total surface area of ​​the comminution discs 8 in the area of ​​the cutting edge profile 12.

[0061] The following is based on the Figure 4The shredding discs shown in section 8 are all basically analogous to the shredding disc according to Figure 3 trained. Differences exist in the details of the design of the cutting edge profile 12.

[0062] Figure 4 Figure 8 shows three shredding discs 8 with corresponding cutting edge profiles 12. Partial figure a) shows a relatively coarse profile with a strong curvature and corresponding lead (rotation direction clockwise in each case). In contrast, the profile in partial figure b) is less curved, among other things, and therefore has a smaller lead. The profile in partial figure c) is even less curved and also has a trail (i.e., a curvature with a less pronounced curve compared to the leading edge). Figure 4a ), b) opposite sign). The shredding discs 8 in Figure 4c ) is suitable for fine meal, which is in Figure 4a ) for pre-shredding and the in Figure 4b ) for a wide range of applications.

[0063] In Figure 5are two shredding discs 8 with different cutting edge angles β (cf. Figure 3 ) shown. According to partial figure a), the cutting edge angle is relatively small, so that the (front in the direction of rotation) cutting edge 13 drops steeply and the profile resembles a sawtooth (see the detail section), whereas partial figure b) shows a variant in which the cutting edge angle is larger and the profile has more trapezoidal elevations.

[0064] In Figure 6Two shredding discs 8 with the same cutting edge angle β (see Figure 3) and correspondingly different unprocessed surface areas 19 are shown. According to partial figure a), the cutting edge angle is again relatively small, so that the (front in the direction of rotation) cutting edge 13 drops steeply, with the profile having only a small unprocessed surface area 19, whereas partial figure b) shows a variant in which the cutting edge angle is also quite small, but the profile nevertheless has a rather large unprocessed surface area 19.

[0065] The detailed section view shown in each case, corresponding to the dashed line, also clarifies the described relationships here, with the reference symbols correspondingly. Figure 3 have been chosen.

[0066] In Figure 7 are two shredding discs 8 with different heights t (cf. Figure 3) of the cutting edges 13 (tooth heights) are shown. According to partial figure a), the height t of the cutting edges 13 is relatively small, whereas partial figure b) shows a variant in which, among other things, the height t of the cutting edges 13 is significantly larger.

[0067] The detailed section view shown in each case, corresponding to the dashed line, further clarifies the described relationships, with the reference symbols again correspondingly. Figure 3 have been chosen.

[0068] Finally, in Figure 8Two shredding discs 8 with different lead-in and lead-out angles are shown. According to partial figure a), the corresponding lead-in angle is negative (counterclockwise or the direction of rotation), so that a lead-out angle (-x) effectively results. In contrast, partial figure b) shows a variant where the lead-in angle is positive, so that a lead-in angle (+x) effectively results. The magnitude of the angle γ is approximately the same in both cases; only the sign changes. Therefore, one can also say that Figure 8a ) shows a relatively small (i.e. negative) lead angle and Figure 8b ) a relatively large (or positive) lead angle.

[0069] The Figure 9 Figures a) and b) show a shredding disc 8 in a top view and a side view, respectively. Reference symbol z denotes a height or vertical direction related to the roller axis L (see, e.g., Figure 1). Figure 3) coincides with or runs parallel to the z-axis. According to partial figure a), the radius of curvature r of the cutting edges 13 varies with increasing distance from the z-axis, where in particular: r₂ > r₁, as shown. Radius of curvature r₁ denotes the course of the cutting edges 13 in the outer boundary region, and radius of curvature r₂ denotes the course of the cutting edges 13 in the inner boundary region. The change in the radius of curvature r can depend linearly on the distance to the z-axis.

[0070] Partial figure b) shows how the shredding disc 8 is designed as a combination of two truncated cones whose (truncated) tips point away from each other. The vertical direction z is parallel to the disc axis or roller axis L (see figure). Figure 3) together or runs parallel to it. The height H of the shredding disc 8 is determined along the z-axis. Accordingly, the curvature of the cutting edges 13 changes depending on the height H of the shredding disc 8 (or one half of the symmetrically constructed shredding disc 8).

[0071] Furthermore, partial figure b) shows that a so-called helix angle λ, defined as the angle between a tangent T to the curved line or to one of the cutting edges 13 and the roller axis or z-axis, varies along the cutting edges 13. Tangent T1 is adapted to the profile of the cutting edges 13 in the outer edge region, and tangent T2 is adapted to the profile of the cutting edges 13 in the inner edge region. The respective helix angle λ1 or λ2 changes along the profile of a given cutting edge 13, increasing here from top to bottom.

Claims

1. Comminution device (1) for comminuting material particles (4), in particular grain or fiber particles, with at least two counter-clockwise driven comminution rollers (2, 3), each having a longitudinal axis (L2, L3) and having an alternating sequence of circumferential grooves (9) and circumferential ribs (10) on their respective outer surface, the flanks (9a, 9b; 10a, 10b) of which extend at an angle ≠ 90° to the longitudinal axes (L2, L3), wherein at least one engagement pair consisting of a circumferential rib (10) of one roller and a circumferential groove (9) of the other roller is formed between the comminution rollers (2, 3), such that a comminution gap (11) is formed between two adjacent flanks, characterized by the fact thatthe flanks (9a, 9b; 10a, 10b) are provided with a cutting edge profile (12) having a plurality of cutting edges (13) and grooves (14), the cutting edges (13) of which have a curved course along a curved line (K), in particular a helix or a conical spiral, which extends from the longitudinal axis (L2, L3, L) of the roller in question along a flank surface to a circumferential edge (15) of the crushing roller in question (2, 3).

2. Comminution device (1) according to claim 1, characterized by the fact that a cutting groove depth (t) is essentially constant along the curved path.

3. Comminution device (1) according to claim 1 or 2, characterized by the fact that a curvature of the line (K) with respect to a direction of rotation of the relevant crushing roller (2, 3) is convex, such that the circumferential ends (16) of the cutting edges have a lead (x; y).

4. Comminution device (1) according to claim 3, characterized by the fact thatthe lead time (x; y) is between 0 degrees and 30 degrees, preferably between 0 degrees and 15 degrees, most preferably between 0 degrees and 7 degrees.

5. Comminution device (1) according to claim 1 or 2, characterized by the fact that a curvature of the line (K) with respect to a direction of rotation of the relevant crushing roller (2, 3) is concave, such that the circumferential ends (16) of the cutting edges (13) have a trail (-x; y).

6. Comminution device (1) according to claim 5, characterized by the fact that the wake (-x; y) is between 0 degrees and 30 degrees, preferably between 0 degrees and 15 degrees, most preferably between 0 degrees and 9 degrees.

7. Comminution device (1) according to any one of claims 1 to 6, characterized by the fact that the cutting edges (13) along their course along the curved line (K) have a variable cutting edge angle (β) relative to a normal direction (N) to the flank surface (18).

8. Comminution device (1) according to claim 7, characterized by the fact that the cutting edge angle (β) is between 0 degrees and 65 degrees, preferably between 5 degrees and 25 degrees, most preferably between 8 degrees and 19.5 degrees.

9. Comminution device (1) according to any one of claims 1 to 8, characterized by the fact that an unprocessed surface fraction (19) of the flanks (9a, 9b; 10a, 10b) over an entire course from one of the respective roller longitudinal axes (L2, L3; L) the inner edge of the cutting edge profile (12) facing to the circumferential edge (15) is essentially constant, preferably minimal, most preferably about zero.

10. Comminution device (1) according to claim 9, characterized by the fact that the surface area (19) is between 5% and 50%, preferably between 10% and 25%.

11. Comminution device (1) according to any one of claims 1 to 10, characterized by the fact that the cutting edges (13) have a curved profile along a three-dimensionally curved line (K).

12. Comminution device (1) according to claim 11, characterized by the fact that a course of the cutting edges (13) follows a shell or conical surface of the comminution rollers (2, 3).

13. Comminution device (1) according to claim 11 or 12, characterized by the fact that a curvature of the line (K) along a conical surface of the crushing rollers (2, 3) or a crushing disc (8) varies, namely a) depending on a height (H) of the conical surface defined in a direction along the longitudinal axis (L) of the rollers, and / or b) in the radius direction, in particular linearly.

14. Comminution device (1) according to one of claims 11 to 13, characterized by the fact that a slope angle (A), which is defined as an angle between a tangent (T) to the curved line (K) and a plane containing the longitudinal axis (L) of the roller, varies along the curved line (K).

15. Comminution device (1) according to any one of claims 1 to 14, characterized by the fact thatthe curved lines (K) are rotationally and / or mirror-symmetric with respect to the longitudinal axis (L) of the roller.

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