Perforated disk for a cutting unit of a comminuting machine

Abstract

The invention, which relates to a perforated disc (1) for a cutting unit of a comminuting machine, addresses the problem of specifying a perforated disc (1) which has improved stability against sagging, is simple to produce and reduces the wear on the perforated disc (1) and on the cutting tool in the cutting unit. This problem is solved in that three bore-free strips (9) of equal length are arranged as chords of the outer circular curve (7) in such a way that in each case two bore-free strips (9) have a common point of intersection (10) within the surface area of the circular ring (5) and subsections (11) of the bore-free strips (9) form an equilateral triangle (12).

Description

[0001] Perforated disc for a cutting unit of a shredding machine

[0002] The invention relates to a perforated disc for a cutting unit of a shredding machine which operates according to a mincing principle and shreds animal or vegetable raw materials, wherein the cutting unit comprises at least one perforated disc and at least one cutting tool, wherein the perforated disc has a bore-free inner ring and a bore-free outer ring which are arranged concentrically to one another, wherein a circular ring is formed between the inner ring and the outer ring, which is delimited by an outer circular curve and an inner circular curve, and wherein a plurality of bores are arranged in the surface of the circular ring which contains a working surface of the perforated disc.

[0003] The invention particularly relates to perforated discs of various sizes with load-adapted support geometries as a design according to bore sizes and their comminution task when load is absorbed as the operating principle.

[0004] State-of-the-art technology involves processing a wide variety of animal or plant raw materials at different temperatures using grinders. These animal or plant raw materials are referred to below as a processing product. Such processing products include foodstuffs of plant or animal origin, such as meat, cheese, fat, fish, skin, bones, and other food components.

[0005] For comminution of the processed material, particularly in the meat industry, so-called grinders with augers for feeding material to a cutting set are generally used as a device for comminuting the processed material, hereinafter referred to as a comminution machine. The so-called thrust force generation for transporting the processed material in such a comminution machine occurs through the interaction of a conveyor screw, the processed material (as the force transmitter), and a screw housing equipped with support elements. The achievable thrust pressure is achieved through the material's strength and the various states of force transmission.

[0006] Such comminution machines comprise at least one conveyor screw within a conveyor housing, wherein a raw material receiving opening for feeding the material to be comminuted is arranged at a first end of the conveyor screw and a cutting unit is arranged at the second end thereof, wherein such a cutting unit comprises at least one perforated disc and associated cutting tools.

[0007] DE 38 23 676 A1 describes a meat grinder, or rather a grinder-like shredding machine, that can be used in all areas of the meat industry. The meat grinder is designed in such a way that a pressure chamber is provided in the pressure housing between the last flight of the pressure and conveyor screw and the cutting unit. The individual adjustment devices for limiting the pressure chamber can be operated from the outside and allow the pressure chamber to be adjusted to the prevailing operating conditions.

[0008] It is also known that such shredding machines employ cutting units consisting of a perforated disc and usually several knives rotating over a surface of the perforated disc as cutting tools for shredding the material. Alternatively, such shredding machines employ a cutting set comprising several combinations of perforated discs and knives.

[0009] The rotating blades of the cutting unit are connected to the conveyor screw by a so-called blade pin, which drives them and sets them in rotation. This ensures that the conveyor screw and one or more blades always rotate in the same position relative to each other. The blades rotate synchronously with the speed of the conveyor screw and in a specific position relative to the conveyor screw.

[0010] The screw rotation generates thrust in the screw conveyor housing with the material to be processed up to the transfer point to the cutting unit. The cutting tools forming the cutting unit are secured in position and clamped in a separate cutting unit housing in front of the screw conveyor, with the cutting unit housing connected to the screw conveyor housing.

[0011] The comminution of the processed material takes place in the cutting unit by means of the perforated disc in a cutting set with several perforated discs with the rotating cutting tools or knives in the knife chamber in that the processed material is pressed into the knife chambers by the thrust pressure generated by the conveyor screw, the pressure in the knife chambers increases and the resulting chunky meat parts (processed material) from the conveying process are compressed to such an extent that shaped elements or pins are formed in the bores of the outflowing perforated disc, which are pressed into the openings of the perforated disc, still connected to the meat part.In this penetration method, the entire cutting capacity of all holes is pushed across the disc surface by the knives, penetrates the holes, and is pressed against the sharp edges of the openings of the perforated disc, thereby separating the pins and shredding the material. The knife, which rotates at the speed of the conveyor screw, does not participate in the separation of the material.

[0012] The typical sequence of the shredding process in the shredding machine includes the feeding of the material to be processed, a transport through the housing of the screw conveyor with simultaneous compaction of the material to be processed by the screw conveyor and the transfer of the compacted material to the cutting unit arranged in the cutting unit housing, whereby the cutting unit housing with the components used is filled with the material to be processed by pressing in by the thrust pressure of the screw conveyor.

[0013] As a result of these processes, a dynamic pressure builds up in the cutting unit housing directly in front of the cutting unit, which, depending on the position between the cutting tools and the conveyor screw, accumulates in a so-called cutting unit pressure. The pressure generated in the cutting unit by the thrust of the conveyor screw generates a high pressing force of the material being processed, which acts on the perforated disc of the independently mounted and clamped cutting unit.

[0014] The holes or openings made in the perforated disc between a hole-free inner ring close to the center and a hole-free outer ring running along the circumference of the perforated disc form the weak point of the perforated disc against deformation forces due to the web spacing between the holes, since the material missing in the perforated disc due to the openings reduces the stability of the perforated disc against deflection.

[0015] The so-called material webs remaining between the holes in the perforated disc are not sufficient to completely prevent the perforated disc from bending.

[0016] According to the known state of the art, it is common for approximately 80% of the surface of the perforated disc, which forms the so-called working area of ​​the perforated disc, to be "open" due to drilled holes. The hole-free material webs partially arranged in the perforated disc according to the state of the art, which support the perforated disc against the deformation forces that occur, comprise approximately 20% of the surface of the perforated disc and reduce the perforated disc's removal capacity at a constant feed rate from the screw, thereby increasing the pressure load on the disc surface. The reason for this is the lack of holes due to the arranged hole-free material webs.

[0017] Conventional perforated discs are therefore very sensitive to the pressure exerted by the cutting unit on the working area of ​​the perforated disc, which leads to deformation of the perforated disc in the form of deflection. This deformation occurs more frequently when processing large pieces of material or at temperatures below 0 °C.

[0018] A particular problem is the fact that meat, the raw material for processing, is not a uniformly produced raw material from a technological process, but develops naturally as a material that evolves during the animal's life cycle. Consequently, its composition is closely linked to the animal's life cycle: movement, hunting, attack, and defense, via the skeleton as the musculoskeletal system, generating power. The raw material is subject to the organizing principle of the living animal in all its functions. So-called lean meat forms a force-conducting muscle structure, which is an "energy mass" protected by collagenous protective layers, while the elements that generate movement, tendons as a high-strength connection to the skeletal parts, initiate the function of movement. This initial situation gives rise to material compositions with parts of extremely high strength and a natural connection to the energy component, the muscles.This makes it a raw material that generates internal counterforces when subjected to stress and lacks predictable technological properties. This is the reason why, to date, there is no truly reliable design for practical applications in raw material processing.

[0019] The deformation forces acting on the perforated disc vary enormously. The material absorption by the perforated discs does not occur linearly, but requires greater compression, which results in bending forces with vibrating elements that vary in size. Generally, such bending forces increase from the circumference or outer ring of the perforated disc towards the inner ring of the perforated disc. The central opening in the disc for the shaft passage forms a particular weak point. The central opening in the disc is also referred to in this description as the opening. Thus, the inner ring, which is arranged around the large opening in the perforated disc, is the most unstable due to its large mass, as the inner ring is not effectively stabilized by the weak load-bearing mass of the circular ring with its many holes.Since this inner ring is only connected in its position by the thin material webs remaining between the perforated disc holes, it has no reinforcing effect on the stability of the perforated disc.

[0020] As a result of the deformation or deflection of the perforated disc in the area of ​​the inner ring, the cutting tools of the cutting unit, such as knives, no longer move closely over the surface of the perforated disc in this area, which reduces their cutting effect in this area by up to 50% and, with increasing wear on the perforated disc and cutting tool, worsens the product quality, throughput effectiveness and cutting quality.

[0021] Since the deformation or deflection of the perforated disc and the effects of the deflection of the perforated disc are known, manufacturers of perforated discs try to avoid or reduce this deflection.

[0022] Known solutions from the prior art include various types of webs arranged radially between the inner and outer rings as support means or support structures for the perforated disc, which do not have bores. Reinforcements of the inner ring and the peripheral area or outer ring of the perforated disc are also known.

[0023] These solutions have not proven successful because they do not sufficiently reduce the deflection of the perforated disc, i.e. they do not sufficiently prevent the deformation effect.

[0024] According to current knowledge, the known support devices or support structures do not allow the perforated disc or the perforated disc working surface to operate permanently and safely in the cutting unit without wear or damage. The known support devices or support structures do not improve the stability of the perforated disc.

[0025] Even if the thickness of the hole disc is quadrupled from 16 mm according to DIN to 35 mm as a limit value due to increasing frictional resistance of the bore lengths, cutting conditions for a safe cooperation of the hole disc with the cutting tool with the cutting tool fully resting on the surface of the hole disc cannot be achieved.

[0026] Therefore, there is a need for an improved perforated disc for a cutting unit of a shredding machine that is more robust against deformation.

[0027] The object of the invention is to provide a perforated disc for a cutting unit of a shredding machine that has improved stability against deflection, is easy to manufacture, and reduces wear on the perforated disc and the cutting tool in the cutting unit. Furthermore, the service life of the perforated disc is to be increased, the maintenance effort and costs of a shredding machine are to be reduced, and product quality and throughput efficiency are to be improved by the largest possible number of holes in the working surface. By only a minor reduction in the number of holes in the working surface, an increase in pressure load on the surface of the perforated disc is to be minimized compared to the prior art.

[0028] This problem is solved by a perforated disc having the features according to claim 1 of the independent patent claims. Further developments are specified in the dependent patent claims.

[0029] The perforated disc according to the invention is intended for use in a cutting unit of a comminution machine that operates according to the mincing principle and comminutes animal or plant raw materials. Such a cutting unit comprises at least one perforated disc and at least one cutting tool, such as one or more knife blades rotating or circulating over a surface of the perforated disc.

[0030] Alternatively, the perforated disc according to the invention can be arranged in a cutting unit comprising several cutting blades, in which several perforated discs and blades of various sizes rotate in operative connection over the surfaces of the perforated discs or cooperate with the rotating blades. In such an application, the perforated discs can be designed differently, for example, with regard to the size of the holes in the perforated discs.

[0031] The perforated disc according to the invention has a bore-free inner ring and a bore-free outer ring, which are arranged concentrically with each other. A circular ring is formed or arranged between the bore-free inner ring and the bore-free outer ring. The surface of the circular ring is bounded by an outer circular curve and an inner circular curve. These two curves are preferably each a circle. The outer circular curve corresponds to an inner diameter of the bore-free outer ring, and the inner circular curve corresponds to an outer diameter of the bore-free inner ring.

[0032] A large number of holes are arranged in the surface of the circular ring, which represents the working area of ​​the perforated disc. These holes are the tools in the form of arranged openings in the perforated disc, into which processing material is pressed in the form of small pieces of meat by the thrust generated by the conveyor screw, filling the knife chamber. Here the pieces become compacted and, from a pressure level of p = 6 bar in the knife chamber, a sudden formation of meat cones begins. These cones are still firmly attached to the meat pieces and penetrate the holes in the perforated disc on the downstream side of the knife blade. The cutting tools rotate or revolve at the speed of the conveyor screw, pushing the entire filling of the knife chamber with the knives over the non-rotating surface of the perforated disc and the resulting meat cones are introduced into the holes.These meat skewers are pressed or moved against the stationary cutting edges of the bores simultaneously with the rotation of the knife and are thus separated at the cutting edges. The knife blades on this side of the second disc have no cutting task, since the filling contents of a knife chamber are always moved between two blades across the disc surface, thus separating the material by pushing it along the cutting edges of the bores and thus shredding it. Ideally, all bores in the surface of the circular ring have the same diameter. However, the position of the knife chambers relative to the conveyor screw results in different filling levels of the knife chambers and thus different cutting results due to varying thrust pressures from the conveyor screw. This leads to fluctuating loads on the circular ring areas of the perforated disc.

[0033] On the perforated disc, the bore-free inner ring is arranged concentrically with the bore-free outer ring, meaning that the inner ring and outer ring have the same center point, with the radius of the inner ring being smaller than the radius of the outer ring. If the outer circular curve and the inner circular curve are each a circle, the radius of the inner circular curve is smaller than the radius of the outer circular curve. The difference in length between the two radii thus results in the width B. k of the circular ring.

[0034] In principle, the invention involves removing the undrilled surface area of ​​the perforated disc located in the center, with its high mass and the hole weakening for the shaft passage (breakthrough) of thin webs between the holes as a deformation element, from the loading process of the cutting and penetration work of the material being processed, and thus separating the working surface of the perforated disc from a load element. This is achieved by tensioning, intersecting tension elements in the form of hole-free strips that absorb and reduce the load effect of the central disc mass. This eliminates the additional loading of the webs in the hole pattern surface of the perforated disc, resulting in greater rigidity of the perforated disc under load.

[0035] In order to improve throughput efficiency by maximizing the number of holes, tie rod profiles in the form of hole-free strips are arranged in the hole plate. These tie rod profiles or hole-free strips are designed or calculated accordingly depending on the cutting plane, load application and hole size in the circular ring. The holding profile of the hole-free strips is such that the width of the hole-free strips is calculated from the diameter of a hole multiplied by a factor between 0.5 and 1.0. This results in minimal drilling losses in the range of 3% to 5% in the area of ​​the hole plate. With hole patterns of this type supported by hole-free strips on a hole plate, the number of active holes in the working area of ​​the hole plate that are involved in the cutting work increases. This corresponds to an increase in performance and thus an increase in throughput efficiency with decreasing pressure load.

[0036] The invention is characterized in that three equally long, hole-free strips are arranged as chords of the outer circular curve such that two hole-free strips each have a common intersection point within the area of ​​the circular ring, and three sections of the hole-free strips form an equilateral triangle. These three equally long, hole-free strips of the perforated disc material are also referred to as tension struts.

[0037] Within the outer circular curve, three equally long, hole-free strips are arranged as chords of the outer circular curve. These three equally long, hole-free strips are arranged such that any two hole-free strips form a common intersection point that lies within the area of ​​the circular ring. Furthermore, the three equally long, hole-free strips are arranged such that three sections of the hole-free strips form an equilateral triangle. This means that each of the three equally long, hole-free strips, with a section belonging to the strip that is shorter than the entire length of the respective hole-free strip, forms one side of the equilateral triangle. The three sections of the hole-free strips can run over the area of ​​the inner ring or through the inner ring.In this way, the hole-free strips absorb the shear forces generated by the material being fed in. The three equally long hole-free strips form tension elements, firmly connected to the sections of the perforated disc across the surface of the perforated disc.

[0038] Such an arrangement of the three hole-free strips forms an equilateral triangle whose center coincides with the center of the perforated disc. Furthermore, two hole-free strips intersect at the intersection point, forming three angles of 60 degrees each, which are the interior angles of the equilateral triangle. Portions of the sides of this equilateral triangle extend tangentially over the area of ​​the inner ring. In this way, the tensile stresses resulting from the deflection of the perforated disc are absorbed by the outer ring, improving the stability of the perforated disc and reducing the deflection of the perforated disc.

[0039] The resulting 60° angle when positioning the three hole-free strips or tension rods not only absorbs forces, but also ensures that the knife blades, with their thrust load from filling the knife chamber, never simultaneously exceed the maximum possible number of holes with inserted meat plugs. Instead, the holes are essentially crossed one after the other and filled with the material being processed. This ensures that the meat plugs located in the holes are never simultaneously pulled out at least partially at the cutting edges and then torn off. This prevents a collagen layer spanning the muscle fibers from extending across multiple holes and thus closing off parts of a subsequent or adjacent hole.When the meat plugs are separated simultaneously according to the current state of the art, due to the congruence of a knife bar with a large number of holes, the knife bar lifts, forming a thin layer of collagen tissue as a covering layer with a sealing effect for many holes simultaneously. This significantly reduces the performance of the perforated disc and its throughput efficiency.

[0040] It is intended that several holes are arranged at least in some areas within this equilateral triangle. Typically, three of these areas are formed within the equilateral triangle.

[0041] The inventive positioning of the three hole-free strips in the outer circular curve and thus within the outer ring provides three support means or support structures within the perforated disc, which absorb tensile forces in the event of deformation of the perforated disc, thus reducing or virtually eliminating deformation of the perforated disc. Such deformations of the perforated disc are caused by the thrust of the conveyor screw, which builds up pressure in the cutting unit, acting on the working area or the surface of the perforated disc.

[0042] The formation of the three intersection points by two intersecting, hole-free strips leads to high stability of the three hole-free strips that absorb tensile forces and thus to high stability within the perforated disc, particularly in the working areas within the circular ring of the perforated disc. This also stabilizes the hole-free inner ring. The perforated disc according to the invention has a central opening in its hole-free inner ring for the passage of a knife drive pin or a drive shaft for the knives. Alternatively, the perforated disc according to the invention has no central opening.

[0043] It is further provided that in areas between the intersection points and the outer circular curve, circular segment-shaped areas are formed, which are delimited by further sections of two intersecting hole-free strips and a circular arc on the outer circular curve.

[0044] The arrangement and alignment of the three hole-free strips described above further results in the formation of circular-segment-shaped regions within the surface of the annulus. Thus, three circular-segment-shaped regions are created in the areas between the intersection points and the outer circular curve. These regions are defined by two sections of two intersecting hole-free strips and a circular arc, with the circular arc lying on the outer circular curve. These circular-segment-shaped regions also contain holes as openings in the perforated disc. The diameters and spacing of these holes correspond to the holes located in the remaining surface of the annulus.

[0045] It is also intended that the circular ring has a width Bk and that the common intersection points of the hole-free strips within the circular ring have a distance from the outer circular curve of B / 2 ± 30%.

[0046] The width B kof the circular ring is the difference between a radius of the outer circular curve, which is designed as a circle, and a radius of the inner circular curve, which is also designed as a circle. The three equally long hole-free strips are arranged within the outer circular curve in such a way that the common intersection points of the hole-free strips lie approximately in the middle between the outer circular curve and the inner circular curve. A deviation from this position can be 10% or 20% or up to 30%. Furthermore, it is provided that the hole-free inner ring has an opening within which an additional device with elements for discharging separated material is arranged.

[0047] Meat is always composed of several intertwined, highly rigid materials. These materials, such as tendons, cartilage, and bone fragments, do not form lumps at normal working pressures due to their high rigidity. They glide across the surface of the perforated disc with the rotating movement of the cutting unit's blades to the center of the perforated disc. There, these fragments can be removed or removed by the additional device for discharging separated material using appropriate elements.

[0048] It has also proven very advantageous to arrange bore-free stabilizing zones in the area of ​​the common intersection points and / or in contact areas where the bore-free strips are connected to the bore-free outer ring. These bore-free stabilizing zones form an increasing force application area for the tension rods, i.e., the bore-free stabilizing zones.

[0049] Such hole-free stabilization areas increase the area or surface of the common intersection points and / or the contact areas, thus ensuring greater stability of the three hole-free strips arranged as a support structure, and thus of the entire perforated disc. Such stabilization areas, in which no holes are arranged, are arranged, for example, at all intersection points where two hole-free strips intersect. The perforated disc has three such intersection points.

[0050] Likewise, such stabilization areas, in which no holes are arranged, are arranged, for example, in all contact areas. These contact areas are areas on the perforated disc in which one end of a hole-free strip is connected to the hole-free outer ring in the area of ​​the outer circular curve. The perforated disc thus has six such contact areas. It is also intended that the hole-free stabilization areas have a circular, semicircular, square, or triangular shape.

[0051] The stabilization areas, in which no holes are arranged, can be circular. In one embodiment, these circular stabilization areas are arranged with their center at the common intersection points. The stabilization areas can have a diameter of up to 7 mm. In one embodiment, a diameter of 3 mm is provided. In general, larger diameters of the holes in the circular ring also increase the diameter of the stabilization areas.

[0052] In an alternative design, the stabilization areas are square or triangular, with their respective centers located at a corresponding common intersection point. For example, a square stabilization area can have sides up to 5 mm long. In general, this variant also increases the side lengths of the square or triangular stabilization areas with larger diameters of the holes in the circular ring.

[0053] The stabilization areas can have a triangular or semicircular shape, particularly in the contact areas.

[0054] It is also advantageous that a ratio of a width B b the hole-free strip to a diameter of a hole in a range between 0.25 to 1 to 1 to 1.5, in particular 0.5 to 1.

[0055] An embodiment of the hole-free strips according to the invention in the working area of ​​the perforated disc with a small width B bhas the advantage that the support structure of the perforated disc, formed by the three hole-free strips arranged according to the invention, requires only a small area in the working area of ​​the perforated disc, which is lost with its cutting function for the material to be processed. This small area is in a range between 3% and 5%, based on the total area of ​​the circular ring of the perforated disc in which holes can be arranged. This small area leads to no or a negligible reduction in the maximum amount of material to be processed per unit of time, since the hole-free strips improve the stability of the perforated disc, thereby improving the comminution work compared to the prior art. According to the prior art, holes in the bent areas of the perforated disc no longer participate in the comminution work.State-of-the-art perforated discs also require larger surfaces for the support elements stabilizing the perforated disc in the working area of ​​the perforated disc due to the greater forces acting on the perforated disc, resulting in a significantly greater reduction in the number of holes in the perforated disc. However, the removal of the material to be processed increases significantly with larger holes, so that ultimately there is no loss of raw material removal. Thus, the maximum amount of material that can be shredded per unit of time is hardly reduced. A reduction in the usable surface area of ​​the perforated disc can be in the range of 10% to 15%. This reduction in the usable surface area of ​​the perforated disc, with the thrust of the material to be processed generated by the conveyor screw remaining the same, causes greater thrust forces on the perforated disc, with a corresponding bending of the perforated disc and the creation of vibrations.

[0056] According to the invention, the ratio of the width Bb of the hole-free strips to a diameter d of a hole is in a range between 0.25 to 1 to 1 to 1.5. This means, for example, with a diameter of a hole arranged as an opening in the perforated disc of d = 3.0 mm, that the width B b a hole-free strip in the range between 0.75 mm and 2.0 mm.

[0057] In particular, it is intended that the ratio of the width B b of the hole-free strip to a diameter of a hole in the ratio of 0.5 to 1. In the case of a diameter of a hole arranged as an opening in the perforated disc of d = 3.0 mm, the width B would be b a hole-free strip in this case 1.5 mm.

[0058] It is also provided that a proportion of the area of ​​the annulus taken up by the three equally long hole-free strips, in which no holes can be arranged, is less than 5%, in particular less than 3%, of the total area of ​​the annulus with its holes. The three hole-free strips arranged according to the invention, which form the equilateral triangle, the common intersection points and the circular sector-shaped regions, create the prerequisite that only a minimal part of the area of ​​the annulus in which holes can be arranged is required for the support structure, i.e. the hole-free strips, which is eliminated as the working area of ​​the perforated disc. Despite this small area of ​​the annulus eliminated according to the invention for the three hole-free strips, a perforated disc that is more resistant to deflection is provided.

[0059] This enables high-quality comminution of the material being processed. It also allows for increased throughput or a larger quantity of material to be processed, since the thrust pressure generated by the conveyor screw in the cutting unit can be higher when using the more deflection-resistant perforated disc according to the invention than when using a perforated disc known from the prior art.

[0060] In addition, the use of the more deflection-resistant perforated disc according to the invention leads to a reduction in material wear on the knives or cutting tools due to the uniform support of the knives of the cutting unit on the perforated disc.

[0061] A further advantage of the hole-free strips arranged according to the invention is that the three hole-free strips on the perforated disc are not aligned in the direction of a radius of the perforated disc or a diameter of the perforated disc. Due to the inventive arrangement and alignment of the hole-free strips, there is no angular correspondence between the running circle of the knives and the blade position of the cutting tool. For this reason, cutting processes in or at the individual holes or openings in the perforated disc essentially take place as individual cuts one after the other and never simultaneously at openings arranged in a row. This reduces the risk of the knives being lifted off by a portion of the material to be processed, in particular collagen fibers or other substances, that gets between the knives and the undrilled areas of the surface of the perforated disc.It is also planned that the hole-free strips, the stabilizing areas, and the other stabilizing areas will be additionally laser-hardened, resulting in a hardness increase of at least 10% in these areas. With the increase in hardness, the stability of the perforated disc will also be improved.

[0062] According to the invention, a groove is further provided in the bore-free outer ring of the perforated disc, and a circular arc is positioned on the outer circular curve at this groove. The groove prevents the perforated disc from twisting when installed in a cutting unit of a shredding machine. The intersecting tie rod profiles in the form of the bore-free strips also protect the perforated disc from breaking open in the area of ​​this groove.

[0063] To secure the perforated disc in the cutting unit of a shredder operating according to the mincing principle, the perforated disc has a groove. Using this groove and a corresponding counterpart, such as a key or wedge, the perforated disc is secured in the shredder to prevent it from twisting.

[0064] As already described, three circular segment-shaped regions are arranged on the outer circular curve, each with its circular arc adjacent to the outer circular curve. One of these circular arcs is intended to be located directly at the groove of the perforated disc. The additional sections belonging to this circular segment-shaped region are part of an X-shaped structure formed between the outer circular curve and the inner circular curve.

[0065] The intersecting, hole-free strips form this X-shaped structure, which has an intersection point. The X-shaped structure, which is arranged at the groove, runs across the working surface or the circular ring of the perforated disc and increases the stability and deformation resistance of the perforated disc, particularly against forces that occur or act in the area of ​​the groove of the perforated disc.

[0066] In a special embodiment of the invention, the walls of the holes drilled into the perforated disc are coated and thus hardened. This results in improved stability of the perforated disc on both sides via the hardened hole walls. The slight additional wall thickness of the holes results in a perforated disc material that is two to three times harder and further improves the stability of the perforated disc, particularly against deflection of the perforated disc. Furthermore, the disc sharpness increases despite knife abrasion on the outer surface of the perforated disc, since the abrasion on the surface of the perforated disc renews or sharpens the cutting edge of each hole from the inside. This eliminates the otherwise occurring process of hole edge rounding.

[0067] The throughput efficiency and stability of the perforated disc can also be improved by diagonally or curvedly arranged bore patterns or openings in the perforated disc. Such diagonally or curvedly arranged bores or openings in the perforated disc are aligned in such a way that an edge of the bores or openings forms a sharp edge, such as a cutting edge, at an angle of less than 90 degrees, opposite to the direction of movement of the material being processed above the surface of the perforated disc, at least in some areas. In this way, the feed of the material into the open bores is improved by up to 30%. In addition, the diagonally arranged bore patterns in the disc cross-section, which may have additional kinks, can redirect the bending forces acting on the perforated disc and reduce them by 20%.

[0068] The above-explained features and advantages of this invention will be better understood and appreciated after careful study of the following detailed description of the preferred, non-limiting exemplary embodiments of the invention with the accompanying drawings, which show:

[0069] Fig. 1 : a view of an exemplary perforated disc according to the invention,

[0070] Fig. 2: a sectional view of the perforated disc according to the invention according to Figure 1,

[0071] Fig. 3: a schematic distribution of tensile forces in the

[0072] Perforated disc and Fig. 4a, 4b, 4c a comparison of the perforated disc according to the invention with perforated discs known from the prior art.

[0073] Figure 1 shows a view of an exemplary perforated disc 1 according to the invention. The perforated disc 1 has a bore-free inner ring 2 and a bore-free outer ring 3, which are arranged concentrically to one another, i.e. have the same center point 4.

[0074] A circular ring 5 is formed or arranged between the bore-free inner ring 2 and the bore-free outer ring 3, wherein a plurality of bores 6 are arranged in this circular ring 5 as openings of the perforated disc 1. In the example of Figure 1, the plurality of bores 6 are arranged substantially uniformly, i.e., at equal distances from one another, resulting in a uniform or regular bore pattern in the circular ring 5 of the perforated disc 1.

[0075] The circular ring 5 has a surface defined by an outer circular curve 7 and an inner circular curve 8. In the example of Figure 1, the circular curves 7 and 8 are circles, with the outer circular curve 7 being the inner diameter of the bore-free outer ring 3 and the inner circular curve 8 being the outer diameter of the bore-free inner ring 2.

[0076] In the area of ​​the surface of the circular ring 5, i.e., within the outer circular curve 7, three equally long, hole-free strips 9 are arranged as chords in the outer circular curve 7. These three hole-free strips 9 are arranged such that two hole-free strips 9 each have a common intersection point 10 within the surface of the circular ring 5. This creates three intersection points 10 in the area of ​​the surface of the circular ring 5. The course of the chords in the outer circular curve 7, which is designed as a circle, is shown in Figure 1 by means of three dashed lines.

[0077] The three equally long, hole-free strips 9 are arranged such that partial sections 11 of the hole-free strips 9 form the sides of an equilateral triangle 12. The three equally long, hole-free strips 9 are further arranged such that six contact areas 13 are formed adjacent to the hole-free outer ring 3, in which the ends of the hole-free strips 9 are connected to the hole-free outer ring 3.

[0078] This means that each hole-free strip 9 runs as chords in the outer circular curve 7 from a first contact region 13, in which the hole-free strip 9 is arranged connected to the hole-free outer ring 3, via the inner ring 2 with the inner circular curve 8 and from there to a second contact region 13, in which the hole-free strip 9 is arranged connected to the hole-free outer ring 3 again, but on a substantially opposite side of the outer ring 3.

[0079] In the example of Figure 1, six triangular, hole-free stabilization areas 14 are arranged in the six contact areas 13.

[0080] Furthermore, additional stabilization areas 15 are arranged at the common intersection points 10. These additional stabilization areas 15 at the common intersection points 10, which are created by crossing the hole-free strips 9, are designed in the example of Figure 1 in the form of quadrilaterals arranged above the intersection areas.

[0081] In addition, the perforated disc 1 has an opening 16 in the area of ​​the bore-free inner ring 2. In this area, several locking elements 17 connected to the inner ring 2 are arranged on the inner ring 2. These locking elements 17 serve to secure a discharge pipe (not shown in Figure 1) of an additional device for discharging separated material.

[0082] In regions between the intersection points 10 and the outer circular curve 7, three circular sector-shaped regions 18 are formed or arranged. These circular sector-shaped regions 18 are each delimited by two further partial sections 19 of two intersecting hole-free strips 9 and a circular arc 20 on the outer circular curve 7. In these circular sector-shaped regions 18, bores 6 are arranged as openings in the perforated disc 1, as in the adjacent regions. At least in partial regions 21 within the equilateral triangle 12, a plurality of bores 6 are arranged. In the example in Figure 1, three of these partial regions 21 are formed in the equilateral triangle 12. One of these partial regions 21 is shown circled in Figure 1.

[0083] To fix the perforated disc 1 in a cutting unit of a shredding machine, the perforated disc 1 has a groove 22. By means of this groove 22, the perforated disc 1 is secured against rotation in the shredding machine by means of a key arranged in a clamping housing of the shredding machine.

[0084] It is intended that a circular arc 20 is arranged directly at the groove 22 of the perforated disc 1. The further sections 19 belonging to this circular arc 20 are part of an X-shaped structure 23 formed between the outer circular curve 7 and the inner circular curve 8. For the sake of clarity, this X-shaped structure 23 is not shown in Figure 1, but in Figure 4b.

[0085] The intersecting, hole-free strips 9 form this X-shaped structure 23, which has an intersection point 10. The X-shaped structure 23, which is arranged at the groove 22, extends over the working surface or the circular ring 5 of the perforated disc 1 and increases the stability and deformation stiffness of the perforated disc 1, in particular against forces that occur or act in the region of the groove 23 of the perforated disc 1.

[0086] Figure 2 shows a sectional view of the perforated disc 1 according to the invention along the section line AA shown in Figure 1.

[0087] The section in Figure 2, viewed from top to bottom, shows the bore-free outer ring 3 with the groove 22, several bores 6, the further stabilizing area 15, again several bores 6, the bore-free inner ring 2, a locking element 17, the opening 16, and the center point 4, shown here as the central axis. Also shown are another locking element 17, again the bore-free inner ring 2, several bores 6, and again the bore-free outer ring 3. Figure 3 shows a schematic distribution of the tensile forces in the bore-free disc 1 that arise when a loaded perforated disc 1 deflects.

[0088] In Figure 3, the perforated disc 1 is shown only schematically. The bore-free inner ring 2 and the bore-free outer ring 3 are visible. Furthermore, the three equally long, bore-free strips 9 are shown as chords of the outer circular curve 7, not shown in Figure 3. The opening 16 can be seen in the center of the perforated disc 1.

[0089] A dashed line and several arrows represent the derivation of the tensile forces resulting from the loading of the perforated disc. This loading of the perforated disc is caused by the thrust of the conveyor screw, which ultimately presses the material being processed against the surface of the perforated disc.

[0090] The hole-free strips 9, as a solid unmachined material component, touch the hole-free inner ring 2 in the center of the perforated disc 1, so that the forces occurring due to the thrust of the conveyor screw against deflection of the perforated disc 1 in the area of ​​the opening 16 are largely compensated by the intersecting hole-free strips 9.

[0091] Figures 4a, 4b and 4c show a comparison of the perforated disc 1 according to the invention with perforated discs known from the prior art.

[0092] Figure 4a shows a first perforated disk known from the prior art which has no support means or support structures. This first perforated disk is most susceptible to the stress or bending described above and therefore offers the least protection against deformations that may occur. Such a first perforated disk has a working area in which approximately 3,900 holes are arranged if this first perforated disk has a diameter of 80 mm. In this working area, it can be assumed that an area of ​​approximately 20% to 30% of the surface of the working area will bend so far with the first few revolutions of the knives during raw material feeding with thrust generation that a distance is created from the knife blade and this area is no longer involved in the comminution process of the processed material.This deterioration in throughput efficiency increases over the entire service life of the perforated disc.

[0093] Measurements have shown that with a diameter of this first perforated disc of 80 mm and a pressure of 12 bar in the chamber of the cutting unit, the deflection of this first perforated disc in the center is 0.652 mm.

[0094] Figure 4c shows another second perforated disc known from the prior art, which has support means or support structures that are arranged in a radial manner. These support means are only aimed at strengthening the center of the perforated disc. This second perforated disc is less susceptible to the stress or bending described above than the first perforated disc. A key feature of such perforated discs is a reduction in the number of holes in the working surface of the perforated disc, with the effect that, due to the constant feed rate of the screw, the pressure on the surface of the perforated disc increases by the degree of the reduction in the number of holes, and the bending as deformation of the perforated disc already occurs at the start of the comminution process and increases much more quickly.

[0095] Consequently, in order to utilize the higher rigidity, the conveying rate must be adjusted to the screw speed to match the removal capacity of the smaller number of holes, which results in a loss of performance or a reduction in the throughput efficiency of the shredding machine.

[0096] However, this improvement in flexural strength by the six 13 mm wide radial support means reduces the number of holes in the working area of ​​the second perforated disc by up to 28%, which leads to a reduction of the number of 3900 holes of the first perforated disc according to the prior art to approximately 2860 holes and to a reduction in the throughput of this second perforated disc when used in a crushing machine.

[0097] Measurements have shown that with a diameter of this second perforated disc of 80 mm and a pressure of 12 bar in the chamber of the cutting unit, the deflection of this second perforated disc in the center is 0.413 mm.

[0098] Figure 4b shows the perforated disc 1 according to the invention, which has three equally long, hole-free strips 9 as support means or support structures as chords of the outer circular curve 7, wherein common intersection points 10 are formed within the area of ​​the circular ring 5 and an equilateral triangle 12. The course of the hole-free strips 9 extends from the outer circular curve 7 over the inner circular curve 8 with the hole-free inner ring 2 in a fixed material connection to the outer circular curve 7, wherein the hole-free strips 9 further extend over two intersection points 10 each. The perforated disc 1 according to the invention is the least susceptible to the loading and bending described above. During examinations and functional checks, any loading of the perforated disc was barely detectable.

[0099] The width B of the hole-free strips 9 of 3.5 mm, shown as an example in Figure 4b, reduces the number of holes in the working area of ​​the perforated disc 1 according to the invention by only about 3%, which leads to a barely noticeable reduction in the throughput of the perforated disc 1 when used in a comminution machine. However, due to the improved dimensional stability of the working surface of the perforated disc according to the invention, the number of holes involved in the comminution process in the working area increases. The flexural strength and service life of this perforated disc are increased. The slightly reduced number of holes 6 of the perforated disc 1 according to the invention compared to a prior art perforated disc according to DIN 9805:2017-02 is 3711 instead of 3900. DIN 9805:2017-02 relates to food processing machines, i.e. pre-cutters and perforated discs for grinders.

[0100] Measurements have shown that with a diameter of the perforated disc 1 according to the invention of 80 mm and a pressure of 12 bar in the chamber of the cutting unit or the chambers of the cutting sets, a deflection of the perforated disc 1 in the center is only 0.03 mm.

[0101] Figure 4b shows the X-shaped structure 23, which is arranged on the groove 22 and extends over the circular ring 5 of the perforated disc 1. List of reference symbols

[0102] 1 perforated disc

[0103] 2 bore-free inner ring

[0104] 3 bore-free outer ring

[0105] 4 Center

[0106] 5 circular ring

[0107] 6 holes (opening)

[0108] 7 outer circular curve

[0109] 8 inner circular curve

[0110] 9 hole-free strips (tendon)

[0111] 10 Intersection

[0112] 11 subsection

[0113] 12 equilateral triangle

[0114] 13 Contact area

[0115] 14 Stabilization area

[0116] 15 additional stabilization areas

[0117] 16 Breakthrough

[0118] 17 Locking element

[0119] 18 circular area

[0120] 19 further section

[0121] 20 circular arcs

[0122] 21 sub-area

[0123] 22 grooves

[0124] 23 X-shaped structure

Claims

Patent claims 1. A perforated disc (1) for a cutting unit of a comminution machine operating according to a grinder principle and comminuting animal or plant raw materials, wherein the cutting unit comprises at least one perforated disc (1) and at least one cutting tool, wherein the perforated disc (1) has a bore-free inner ring (2) and a bore-free outer ring (3), which are arranged concentrically to one another, wherein a circular ring (5) is formed between the inner ring (2) and the outer ring (3), wherein a surface of the circular ring (5) is delimited by an outer circular curve (7) and an inner circular curve (8), and wherein a plurality of bores (6) are arranged in the surface of the circular ring (5), which contains a working surface of the perforated disc, characterized in that three equally long bore-free strips (9) are arranged as chords of the outer circular curve (7) in such a way thatthat two hole-free strips (9) each have a common intersection point (10) within the area of ​​the circular ring (5) and partial sections (11) of the hole-free strips (9) form an equilateral triangle (12).

2. Perforated disc (1) according to claim 1, characterized in that in areas between the intersection points (10) and the outer circular curve (7) circular segment-shaped areas (18) are formed, which are delimited by further partial sections (19) of two intersecting hole-free strips (9) and a circular arc (20) on the outer circular curve (7).

3. Perforated disc (1) according to claim 1 or 2, characterized in that the circular ring (5) has a width B k and that the common intersection points (10) of the hole-free strips (9) within the circular ring (5) are at a distance from the outer circular curve (7) of B k / 2 ± 30%.

4. Perforated disc (1) according to one of claims 1 to 3, characterized in that the bore-free inner ring (2) has an opening (16) and that locking elements (17) connected to the inner ring (2) are arranged.

5. Perforated disc (1) according to one of claims 1 to 4, characterized in that in the region of the common intersection points (10) and / or in contact regions (13) in which the hole-free strips (9) are arranged connected to the hole-free outer ring (3), hole-free stabilizing regions (14, 15) are arranged.

6. Perforated disc (1) according to one of claims 1 to 5, characterized in that the bore-free stabilizing regions (14, 15) have a circular, semicircular, square or triangular shape.

7. Perforated disc (1) according to one of claims 1 to 6, characterized in that a ratio of a width B bthe hole-free strip (9) to a diameter d of a hole (6) is in a range between 0.25 to 1 to 1 to 1, in particular 0.5 to 1.

8. Perforated disc (1) according to one of claims 1 to 7, characterized in that a proportion of the area of ​​the circular ring (5) occupied by the three equally long hole-free strips (9), in which no holes (6) can be arranged, is less than 5%, in particular less than 3%, of the total area of ​​the circular ring (5).

9. Perforated disc (1) according to one of claims 1 to 8, characterized in that a groove (22) is arranged in the bore-free outer ring (3) of the perforated disc (1) and that a circular arc (20) on the outer circular curve (7) is positioned at this groove (22).

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