Cutting set for a comminuting machine, and method for producing same

Abstract

The aim of the invention, which relates to a cutting set for a comminuting machine and to a method for producing same, is to improve the prior art and to provide a solution by means of which the stability and positional securing of the tools, rotating cutting tool, perforated disk, and drive pin, in the cutting set is improved, the quality of the processing of the material to be processed is ensured, and the service life of the tools is extended due to less wear. This aim is achieved by means of an arrangement in which a first hollow-cylindrical collar is arranged on the first cutting tool of the cutting set.

Description

[0001] Cutting set for a shredding machine and method for manufacturing

[0002] The invention relates to a cutting set for a shredding machine, wherein at least a first cutting tool, a first perforated disc and a drive pin are arranged in the cutting set.

[0003] The invention also relates to a method for production in which at least a first cutting tool, a first perforated disc and a drive pin are provided in a cutting set of a comminution machine.

[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 processed material, particularly in the meat industry, grinders with augers are typically used to feed the material to a cutting set as a device for comminution. Thrust to transport the processed material in such a grinder is generated through the interaction of a transport and working auger, the material being processed as the force transmitter, and a screw housing of the grinder equipped with supporting elements. The achievable thrust is achieved through the material strength with the various states of force transmission. Such transport and working augers are also referred to as conveyor screws.

[0006] The shredding machines comprise at least one transport and processing screw within a conveyor housing. A raw material intake opening for feeding the material to be shredded is arranged at a first end of the transport and processing screw, and a cutting set is arranged at the second end. Such a cutting set comprises at least one perforated disc with openings and an associated rotating cutting tool with multiple cutting edges, also referred to as knives. In general, the cutting edge refers to the part of a blade or knife or knife base body with which the cutting process takes place.

[0007] Such a cutting tool is designed, for example, in the form of a rotating disk with several cutting edges arranged on a surface of the rotating disk. For example, one to six rotating cutting edges are arranged on the surface of the rotating cutting tool. In one design, the cutting edges are essentially radially aligned and arranged at equal distances or angles to one another on the surface of the disk-shaped cutting tool. Two or three of these rotating cutting tools are usually arranged within a cutting set. Discs with bores are usually arranged next to these rotating cutting tools. The cutting tools are usually arranged between two discs on a disc plane.

[0008] In an exemplary embodiment, the cutting set comprises a first cutting tool, a first perforated disc, a second cutting tool and a second perforated disc, such as a pre-cutter.

[0009] Typically, a cutting tool is mounted with its cutting edges on a driven shaft, such as a drive pin or knife pin of a shredding machine, and is set in rotation by this drive pin. The drive pin itself is usually connected to the transport and working screw in such a way that the rotary motion of the transport and working screw, which is connected to a drive means, is transmitted synchronously to the drive pin.

[0010] It is known from the prior art to arrange tools of a shredding machine, such as a rotating cutting tool and a perforated disk, referred to as a cutting set, in a housing or cutting component housing of the shredding machine. The tools are mounted by their position in the cutting component housing and by sub-elements on and in the tools themselves via a drive pin connected to the transport and working screw. In the prior art, bearing elements such as bushings in conjunction with the center holes of a cutting tool or a perforated disk are the most common application. External bearing elements are usually not inserted into the center holes.

[0011] For higher loads on shredders, it is common to use bearing materials alone or with force-absorbing bushings to support cutting tools and / or perforated discs. This type of bearing is used, for example, in the pre-cutting area and / or in the frontmost disc area of ​​the shredder's cutting set.

[0012] It is also known that so-called support crosses, which are also used as clamping elements in front of the tool combinations in the cutting set, are used with a union nut to adjust the cutting conditions between the tools.

[0013] It is common practice to use them, for example, in the shape of a Mercedes star with an open center hole for the passage of a drive shaft or drive pin. A bushing material can also be used in the center holes of the cutting tool or the perforated disc to support the drive pin.

[0014] With this design, both the transport and working auger, as well as the drive pin, also known as the knife pin, are mounted in the cutting set. The drive pin is only supported in sections along its longitudinal extension.

[0015] Due to the required increase in performance of new shredding machines, the processing of large pieces of material, frozen meat parts, or other materials places significant stress on components within a shredding machine, even leading to overloading. Of particular note here is wear in the area of ​​a so-called knife bushing made of a bearing material, i.e., a bushing of the cutting tool in a portion of the central bore of the disc-shaped cutting tool. This wear occurs regardless of whether the cutting tool is designed with a collar for position centering between the cutting tool and, for example, two perforated discs, or whether the center hole of the cutting tool is adapted to the size of the diameter of the drive pin, thus eliminating the need for a collar.As a result of this wear and / or heavy stress, severe abrasion marks occur due to tool jamming. The cause of this tool wear is primarily deformation or bending of the transport and working screws away from their longitudinal axes, which will be explained in more detail below.

[0016] Wear and abrasion, particularly due to bending of the conveyor and working screws, indicate that the collars and bushings previously provided on the cutting tools, which function as familiar bearing elements, are no longer sufficient to ensure proper operation with sufficiently long service life for the cutting set tools. Wear and abrasion also lead to a deterioration in the quality of the material processed with the shredder and to a decrease in the processable quantity of material per unit of time.

[0017] Consequently, additional bearing elements were developed that are provided externally and are usually pressed into the cutting tools, such as a pre-cutter in the form of a replaceable bushing, to improve the bearing quality for the shredder's tools. In practice, it has been found that the bearing materials used as replaceable bushings in the cutting tools, such as high-quality bronze, do not fulfill these tasks reliably, especially not permanently, and also wear out.

[0018] For this reason, even more resilient materials are being sought and tested for use in the tools of shredding machines.

[0019] A significant disadvantage of the known prior art is that due to an uneven load when feeding the material to be processed into the shredding machine through the raw material intake opening, a one-sided load on the transport and working screw occurs with forces which are directed from the hopper wall of the raw material intake to a longitudinal axis of the transport and working screw and thus essentially at right angles to the longitudinal axis of the transport and working screw.

[0020] These forces cause the transport and working screw to deflect or bend away from its longitudinal axis. This deflection in the open area of ​​the raw material feed of the transport and working screw also results in a deflection or bending of the drive pin connected to the transport and working screw in the area of ​​the cutting set. However, this drive pin, which is also deflected and bent away from its longitudinal axis, is not designed to absorb these forces. This results in the tools, particularly the cutting tools and their cutting edges, becoming jammed. The longitudinal axes of the transport and working screw and the drive pin are aligned, at least in a load-free state.

[0021] Since the rotating cutting tool, mounted and driven by the drive pin, is always preloaded and aligned in its own housing at a right angle to the longitudinal axis of the drive pin. Even the slightest bending of the drive pin also changes the alignment of the cutting tool. This results in a jamming between the rotating cutting tool and its cutting edges and the friction surfaces of the adjacent perforated disc. This means that a surface of the cutting tool on which the cutting edges are arranged no longer rotates parallel to the surface of the adjacent perforated disc. The reason for this lies in the bending of the drive pin and the firm fixation of the perforated disc in the housing of the cutting section of the shredder.In other words, while the perforated disc is firmly fixed or clamped in the housing, the orientation of the surface of the cutting tool, which can have cutting edges on both sides, changes relative to the surface of the perforated disc depending on the bending of the transport and working screw as well as the drive pin.

[0022] As a result of this load-induced bending of the drive pin, the distance between the cutting edges of the cutting tool and the surface of the adjacent perforated disc changes as the cutting tool rotates. As the distance between a cutting edge of the cutting tool and the surface of the perforated disc increases, the cutting properties of the cutting edge deteriorate, and consequently, the comminution of the material being processed is impaired. The shape or geometry of the tools is destroyed.

[0023] If the gap between a cutting edge of the cutting tool and the surface of the perforated disc is too small, the cutting edge will rub or scrape against the surface of the perforated disc. This results in undesirable abrasion on the surface of the perforated disc and on the cutting edge. In some cases, this also leads to the destruction of the cutting edge and / or the edges of the holes or bores in the perforated disc.

[0024] Increased wear occurs on the cutting edges of the cutting tool, especially on the outer surface of the perforated disc. Lifting of the cutting edges from the surface of the perforated disc can result in a performance loss of more than 50%.

[0025] Thus, there is a need for an improved cutting set for a shredding machine and an improved method for manufacturing tools for the cutting set of the shredding machine.

[0026] The object of the invention is therefore to improve the state of the art and to provide a solution by which the stability and positional security of the tools, rotating cutting tool, perforated disc and drive pin in the cutting set is improved, the quality of the processing of the material to be processed is ensured and the service life of the tools is extended by reduced wear.

[0027] In addition, perforated discs should be more resistant to deformation and offer superior cutting properties. The solution should also enable cost-effective production of the tools in the cutting set and reduce the removal of hazardous metal particles and their introduction into the shredded material. The term "stability" of the rotating cutting tool and the perforated disc describes the strength and robustness of the tools. Stable and robust tools withstand heavy loads during operation in the cutting set of the shredder and achieve correspondingly long service life. Because these stable tools are replaced later than with state-of-the-art tools, the costs for repairs and maintenance work are also reduced.

[0028] The term "positional security" for the rotating cutting tool and the perforated disc describes a parallel alignment of the surface of the rotating cutting tool to the surface of the non-rotating perforated disc. In another example, the perforated disc can also be a perforated disc in the form of a pre-cutter. This type of positional security ensures a stable parallel alignment of the surfaces of the tools to each other and reduces wear on the tools. Furthermore, the quality of the material processed with the shredding machine is improved and the service life of the tools is increased.

[0029] The problem is solved by a cutting set for a shredding machine having the features according to claim 1 of the independent claims. Further developments are specified in the dependent claims.

[0030] In a cutting set of a shredding machine according to the invention, at least one first cutting tool with several cutting edges, a perforated disc and a drive pin are arranged in a so-called cutting plane.

[0031] According to the invention, a first hollow-cylindrical collar is arranged on the first cutting tool of the cutting set. This creates a load-bearing collar for the center hole of the first cutting tool or the first tool combination, consisting of the first cutting tool and an associated perforated disc.

[0032] A first hollow-cylindrical collar according to the invention is arranged on the first cutting tool. This first hollow-cylindrical collar, which is a component of the first cutting tool, is designed in the form of a hollow cylinder and is arranged on one side of the first cutting tool. The first cutting tool can also be used for application in a pre-cutter. The first hollow-cylindrical collar consists of the same material as the base body of the first cutting tool, for example, steel. The first hollow-cylindrical collar is arranged on the first cutting tool in such a way that a longitudinal axis of the first hollow-cylindrical collar is aligned with, or coincides with, a rotational axis and the center hole of the first cutting tool.

[0033] A central opening of the first hollow-cylindrical collar and a central opening of the first cutting tool form a uniform, continuous opening whose internal geometry matches the external geometry of a force-transmitting drive pin. The internal geometry of the first hollow-cylindrical collar and the first cutting tool is adapted to the external geometry of the drive pin in order to transmit a rotational movement of the driven drive pin to the first cutting tool to generate cutting force. The internal and external geometries correspond to one another and provide a positive connection between the drive pin and the first cutting tool.

[0034] In this description, "corresponding" means that a shape, for example, two-edged, triangular, square, hexagonal, and any special shapes, which the drive pin according to the invention has, are adapted to the unit consisting of the cylindrical collar and the cutting tool, thus enabling a positive connection for the bearing function. This positive connection leads to a fixed alignment between the cutting edges of the cutting tool with the perforated disc and a position of a transport and working screw, at which the drive pin is fixedly arranged. Thus, the cutting tool rotates at the speed of the transport and working screw.

[0035] The first hollow-cylindrical collar has a wall thickness between its inner diameter and its outer diameter, which ranges from 5 mm to 10 mm. The wall thickness is based on the load-bearing length or the thickness of the disc mounted on the first hollow-cylindrical collar, such as a perforated disc. The term "load-bearing length" describes the thickness of the perforated disc.

[0036] It is further provided that a second hollow cylindrical collar is arranged on a second cutting tool of the cutting set.

[0037] Such a second cutting tool also has several cutting edges arranged on it. This cutting tool is used, for example, as a pre-cutting tool in the cutting set of the shredder and, viewed in one direction of the material flow of the processed material in the shredder, is arranged upstream of the first cutting tool, which is also referred to as the main cutting tool.

[0038] A second hollow-cylindrical collar according to the invention is arranged on the second cutting tool. This second hollow-cylindrical collar, which is a component of the second cutting tool, is also designed in the shape of a hollow cylinder and is arranged on one side of the second cutting tool. The second hollow-cylindrical collar is also made of the same material as the base body of the second cutting tool, for example, steel. The second hollow-cylindrical collar is arranged on the second cutting tool in such a way that a longitudinal axis of the second hollow-cylindrical collar is aligned or coincides with a rotational axis and the center hole of the second cutting tool.

[0039] These supporting arrangements of the first hollow cylindrical collar and the second hollow cylindrical collar stabilize the tools and reduce deformation and wear.

[0040] A central opening of the second hollow-cylindrical collar and a central opening of the second cutting tool form a uniform, continuous opening, the internal geometry of which corresponds to the external geometry of a force-transmitting drive pin. The internal geometry of the second hollow-cylindrical collar and the second cutting tool are adapted to the external geometry of the drive pin in order to transmit a rotary movement of the driven drive pin to the second cutting tool. In this case, too, the internal and external geometry correspond to one another and establish a positive connection between the drive pin and second cutting tool components.

[0041] The second hollow cylindrical collar also has a wall thickness between its inner diameter and its outer diameter, which is in the range between 5 mm and 10 mm.

[0042] Furthermore, according to the invention, it is provided that the first hollow cylindrical collar has a first length which corresponds to a thickness of the perforated disc.

[0043] In addition, according to the invention, it is provided that the second hollow cylindrical collar has a second length which corresponds to a thickness of a pre-cutter.

[0044] In particular, it is provided according to the invention that the first hollow cylindrical collar has a first length which corresponds to a thickness of the perforated disc and that the second hollow cylindrical collar has a second length which corresponds to a thickness of a pre-cutter.

[0045] Thus, according to the invention, the storage of the tools perforated disc and pre-cutter is improved, whereby canting in the cutting planes of the first cutting tool and perforated disc or the second cutting tool and pre-cutter is reduced.

[0046] The length of the first hollow cylindrical collar formed on the first cutting tool and protruding from the first cutting tool corresponds to the thickness of a perforated disc mounted on the first hollow cylindrical collar. This refers to the maximum thickness of the perforated disc or the depth of a central bearing bush of the perforated disc in the direction of a rotational axis of the perforated disc.

[0047] Furthermore, a length of the second hollow-cylindrical collar formed on the second cutting tool and protruding from the second cutting tool corresponds to a thickness of a pre-cutter mounted on the second hollow-cylindrical collar. This refers to a maximum thickness of the pre-cutter or the depth of a central bearing bush of the pre-cutter in the direction of a rotational axis of the pre-cutter. Thus, according to the invention, closed, supporting, and force-absorbing bearings are formed in the respective cutting planes by the tool combinations of the first cutting tool and perforated disc, or the second cutting tool and pre-cutter.

[0048] It has been found to be particularly advantageous that the hollow cylindrical collar has a two-edged, triangular, square or hexagonal inner diameter and a second partial area of ​​a drive pin has a two-edged, triangular, square or hexagonal outer diameter corresponding to the hollow cylindrical collar.

[0049] This design ensures a positive placement of the first cutting tool with its first collar and / or the second cutting tool with its second collar on the corresponding drive pin.

[0050] It is also provided that a first bearing surface is formed on the first hollow-cylindrical collar, on which the perforated disc is arranged with its inner surface, and that a second bearing surface is formed on the second hollow-cylindrical collar, on which the pre-cutter is arranged with its inner surface.

[0051] According to the invention, a first bearing surface is formed on the first hollow-cylindrical collar of the rotating first cutting tool, which first bearing surface serves as a sliding bearing for a tool arranged adjacent to the first cutting tool in the cutting set of the comminution machine, such as a perforated disc. The first bearing surface corresponds to an outer surface of the first hollow-cylindrical collar.

[0052] The first plain bearing is formed by a lateral surface of the first hollow cylindrical collar, i.e. the outer surface of the first hollow cylindrical collar, and an inner surface of a central opening in the perforated disk. The outer surface of the first hollow cylindrical collar and the inner surface of the central opening in the perforated disk are provided with coated or hardened surfaces, which increase the service life of the tools and reduce wear. Furthermore, a second bearing surface or a second plain bearing is formed on the second hollow cylindrical collar of the rotating second cutting tool for a tool in the cutting set of the shredding machine, such as a pre-cutter, arranged adjacent to the second cutting tool. The second bearing surface corresponds to an outer surface of the second hollow cylindrical collar.

[0053] The second plain bearing is formed by a lateral surface of the second hollow-cylindrical collar, i.e., the outer surface of the second hollow-cylindrical collar, and an inner surface of a central opening in the pre-cutter. The outer surface of the second hollow-cylindrical collar and the inner surface of the central opening in the pre-cutter are provided with coated or hardened surfaces, which increase the service life of the tools and reduce wear.

[0054] According to the invention, the outer surfaces and the inner surface of both plain bearings are treated by means of a nitriding process, whereby the surfaces are hardened accordingly and their bearing properties are improved.

[0055] In this embodiment, the perforated disc is arranged on the first bearing surface of the first cutting tool and the pre-cutter is arranged on the second bearing surface of the second cutting tool in the cutting set, while the first cutting tool and the second cutting tool are arranged on the drive pin.

[0056] The inventive arrangement of the first hollow-cylindrical collar on the first cutting tool creates a larger internal bearing surface for the first cutting tool relative to the drive journal than is the case with the prior art. This increases the bearing surface for the first cutting tool on the drive journal over a maximum achievable support area, and avoids concentrated point loading caused by the transverse position of the first cutting tool relative to the perforated disk arranged parallel to the surface of the first cutting tool. These measures reduce wear and increase the service life of the tools in the cutting set. This improved bearing arrangement applies analogously to the second cutting tool with its second hollow-cylindrical collar.

[0057] As a result of this improved bearing arrangement, the canting between the rotating cutting tool with its cutting edges and the adjacent associated perforated disk, which is known from the prior art, is reduced. Likewise, the canting between the rotating cutting tool with its cutting edges and the adjacent pre-cutter, which is known from the prior art, is reduced. This improved bearing arrangement reduces canting of the tools in the cutting set by up to 90%. In addition, stabilization of the transport and working screw is achieved by a section of the drive pin, which is surface-treated according to the invention using a nitriding process and is arranged in the transport and working screw.

[0058] The load, for example, on the outer peripheral area of ​​the perforated disc and the cutting edges of the first cutting tool due to the canting known from the prior art is significantly reduced or even avoided by enlarging the inner bearing surface of the first cutting tool.

[0059] The service life and the achievable processing performance are improved by enlarging the inner bearing surface of the first cutting tool and the associated better support or alignment of the cutting edges of the first rotating cutting tool relative to the surface or top side of the perforated disc.

[0060] This improvement in service life and achievable processing performance applies analogously to the second cutting tool with the pre-cutter.

[0061] The cutting tools arranged in the cutting set each have several cutting edges. The number of cutting edges ranges from two to six per cutting tool.

[0062] In an advantageous embodiment of the invention, it is provided that the first cutting tool is arranged with its first hollow cylindrical collar in a twisted manner on the drive pin of the shredding machine, wherein the drive pin is arranged on a driven transport and working screw of the shredding machine.

[0063] In a further advantageous embodiment of the invention, it is provided that the second cutting tool with its second hollow cylindrical collar is arranged in a twisted manner on the drive pin of the shredding machine, wherein the drive pin is arranged on a driven transport and working screw of the shredding machine.

[0064] In a particularly advantageous embodiment of the invention, it is provided that the first cutting tool with its first hollow cylindrical collar and the second cutting tool with its second hollow cylindrical collar are arranged in a twisted manner on the drive pin of the shredding machine, wherein the drive pin is arranged on a driven transport and working screw of the shredding machine.

[0065] The transport and working screw located in the shredding machine is connected to a drive mechanism that sets the transport and working screw in rotation. This ensures the transport of the material to be processed in the shredding machine from an area of ​​the open, funnel-shaped raw material feed to the area of ​​the shredding machine's cutting set.

[0066] In order to also set the first cutting tool and the second cutting tool in rotation, the drive pin, on which the cutting tools are arranged in a form-fitting and twisted manner, is connected to the transport and working screw. The transport and working screw has a corresponding mounting geometry to at least partially accommodate the drive pin in a twisted manner in the transport and working screw. In this way, the rotational movement of the driven transport and working screw is transmitted to the cutting tools via the drive pin. A separate drive means for the cutting tools is therefore not necessary. In an alternative embodiment, the drive pin is connected to a driven screw shaft on which the transport and working screw is arranged.It is also provided that the openings in the perforated disc are straight bores, wherein a longitudinal axis of the straight bore is aligned at right angles to a circular surface or upper side of the perforated disc, or that the openings in the perforated disc each have a course with two partial areas, wherein the first partial area is designed in the form of an oblique cylinder, the longitudinal axis of which is aligned at an angle between 20 degrees and 40 degrees, in particular at an angle between 20 degrees and 30 degrees, especially at an angle of 25 degrees, to the circular surface or upper side of the perforated disc, and wherein the second partial area adjoining the first partial area in the opening is designed in the form of a straight cylinder, the longitudinal axis of which is aligned at right angles to the surface of the perforated disc.

[0067] In one variant of the design of the openings in the perforated disc, a non-rectilinear course of the openings in the perforated disc is provided in a two-part design. In this design, each opening comprises two adjacent partial areas arranged one behind the other in the opening. This opening runs from a first circular surface of the perforated disc, referred to here as the top side of the perforated disc, to an opposite second circular surface of the perforated disc, referred to here as the bottom side of the perforated disc, and thus penetrates the perforated disc. The top side of the perforated disc is aligned parallel to the bottom side of the perforated disc.

[0068] The first section of the opening is designed in the shape of an oblique cylinder, and the second section adjoining the first section in the opening is designed in the shape of a straight cylinder. In this variant, the longitudinal axis of the first section is aligned at an angle between 20 degrees and 40 degrees, in particular at an angle between 20 degrees and 30 degrees, specifically at an angle of 25 degrees, to the first circular surface or upper side of the perforated disc.

[0069] The longitudinal axis of the second sub-area is oriented perpendicular to the opposite, second circular surface or underside of the perforated disc. The longitudinal axis of the second sub-area is also oriented perpendicular to the top side of the perforated disc, since the top side of the perforated disc is aligned parallel to the underside of the perforated disc.

[0070] In one embodiment, the first circular surface or upper side of the perforated disc is a raw material inlet side, while the second circular surface or lower side of the perforated disc is a raw material outlet side for the processed material.

[0071] Such a design of a non-rectilinear opening in the perforated disc, comprising two sub-areas, can advantageously be produced using a 3D printing process. With such a 3D printing process, all intended openings in the perforated disc are created in a single operation, along with their spatial, geometric progression. In one embodiment, this spatial, geometric progression encompasses both sub-areas.

[0072] In a further development of the invention, it is provided that partial areas of the opening or the entire opening have a non-rectilinear course, in particular a course curved in a predetermined radius from the upper side of the perforated disc to the underside of the perforated disc.

[0073] An advantage of arranging a first sub-area, for example in the form of an oblique cylinder on the upper side of the perforated disc, over which the cutting edges of the cutting tool slide, is that an almost semicircular sharp-edged cutting edge of the opening is formed on the upper side of the perforated disc, which is formed at an angle of less than 90 degrees, i.e. at an acute angle, and thus improves the comminution process of the material to be processed.

[0074] The alignment and positioning of each opening in the perforated disc, for example at an angle of 20 degrees, between a longitudinal axis of the opening and a vertical on the upper side of the perforated disc, is such that a cutting edge of the cutting tool sliding over the upper side of the perforated disc first reaches a first, almost semicircular part of the opening with its cutting edge, which at a maximum forms an obtuse angle of 110 degrees between the longitudinal axis of the opening and the surface of the upper side. Subsequently, the cutting edge of the cutting tool sliding over the upper side of the perforated disc reaches a second, almost semicircular part of the opening on the upper side of the perforated disc, which forms the cutting edge of the opening. This cutting edge of the opening has a minimum acute angle of 70 degrees between the longitudinal axis of the opening and the surface of the upper side.Thus, the openings in the perforated disc are aligned differently depending on their position in the perforated disc in order to fulfill the above-mentioned condition.

[0075] The material to be processed, sliding across the surface of the perforated disc, is first guided over the almost semicircular part of the opening, which forms an obtuse angle to the surface of the upper side. The material to be processed is conveyed into the opening of the perforated disc in the area of ​​the opening, which is facilitated by the angled orientation of at least a portion of the opening. Finally, the material to be processed is crushed at the semicircular part of the opening on the upper side of the perforated disc, which forms the cutting edge of the opening. The angled position of the openings on the raw material inlet side of the perforated disc improves the conveyance of the material to the openings and the crushing process.

[0076] Furthermore, the present invention provides that the ratio of the lengths of the first partial region to the second partial region lies in a range from 1 / 3 to 1 / 2 to 2 / 3 to 1 / 2. In this way, stabilization of the openings against external forces can be achieved and adjusted.

[0077] The problem is also solved by a method having the features according to claim 11 of the independent patent claims. Further developments are specified in the dependent patent claims.

[0078] In a method for producing a cutting set, at least one first cutting tool with multiple cutting edges, a perforated disc with openings, and a drive pin are provided as tools of the cutting set of a comminution machine. In an alternative embodiment of the cutting set of the comminution machine, a first cutting tool with multiple cutting edges and a perforated disc, as well as a second cutting tool with multiple cutting edges and a pre-cutter, are provided.

[0079] According to the invention, an entire surface of the perforated disc is hardened by means of a nitriding process after production of this tool, whereby a Rockwell hardness in a range of 70 HRC to 73 HRC is produced on this surface.

[0080] It is further provided that surfaces of the cutting edges of the cutting tool are hardened by means of a nitriding process after manufacture of this tool, whereby a Rockwell hardness in a range of 70 HRC to 73 HRC is produced on this surface.

[0081] It is also provided that surfaces of the drive pin are hardened by means of a nitriding process after manufacture of this tool, whereby a Rockwell hardness in a range of 70 HRC to 73 HRC is produced on this surface.

[0082] To improve the stability of the rotating cutting tool with its cutting edges, the perforated disk with its openings, and the drive pin, one component, preferably two components, and particularly preferably all three components of the cutting set are hardened after their manufacture using a nitriding process. In particular, such a nitriding process makes the entire surface of the tools and the drive pin more stable and harder by incorporating nitrogen atoms into the tool material, such as steel.

[0083] Such nitriding processes are known from the state of the art for hardening the surfaces of workpieces made of steel, for example. Nitriding is also referred to as nitriding.

[0084] The nitriding process changes the properties of surfaces and areas near the surfaces. One such property is increased strength of the workpieces machined in the process, such as cutting tools, perforated disks, and drive pins. This increases the hardness, at least in limited local areas of the entire surface of the nitrided workpiece or object. The workpiece is machined in the nitriding process in a nitrogen-enriched environment at a temperature of approximately 500°C to 590°C and a treatment time of 20 to 70 hours, during which nitrogen atoms diffuse into the microstructure of the workpiece material. The nitrogen atoms are incorporated into the lattice structure of the material and thus represent an integral part of the material in the outer region of the workpiece. Processes such as gas nitriding, bath nitriding, vacuum nitriding, and plasma nitriding are known in practice when using nitrogen.

[0085] The diffusion of nitrogen atoms, with a strong structural bond within the material, forms a very hard superficial nitriding layer covering the entire surface of the workpiece. Depending on the temperature used and the treatment time, the nitriding layer develops to a thickness of a few tenths of a millimeter. According to the invention, this hardened nitriding layer on the cutting tool, on and in the holes of the perforated disk, or on the drive pin has a layer thickness in a range of 0.1 mm to 0.7 mm, in particular 0.5 mm.

[0086] The resulting nitriding layer can exhibit more or less pronounced pore edges across the entire surface, which are used in practice as lubricant carriers. It is generally known that the longer the treatment time, the thicker the resulting nitriding layer becomes. The higher the treatment time and temperature used in the process, the deeper the nitrogen atoms can penetrate into the workpiece per unit of time.

[0087] According to the invention, a closed surface nitriding layer improves robustness against compressive forces, vibrations and frictional forces.

[0088] According to the invention, after the formation of a continuous surface nitriding layer on a cutting tool, the longitudinally extending cutting edges on the cutting tool are further ground with a so-called sharpening process, whereby a portion of the surface nitriding layer is removed from one surface of the cutting edges, and two sharp edges are formed in the front along the longitudinal extension of each cutting edge on both sides. During operation of the cutting set, these cutting edges are aligned parallel and perpendicular to the surface or top side of the associated perforated disc or the associated pre-cutter.

[0089] With this type of sharpening, the continuous nitriding layer on the surfaces of the cutting edges or cutting geometry is intentionally removed, at least partially or completely, to form two sharp edges along the length of each cutting edge. The objective here is to prevent rounding due to the blocking effect of the hard nitriding layers in front of the cutting edges and thus largely eliminate the formation of burrs in the soft base material located between the nitriding layers, which can act as a wear zone for metal burrs across the blade width.

[0090] These sharp edges of the cutting edges have, for example, an angle of approximately 90 degrees or a slightly lowered position and are formed by an edge area of ​​the ground surfaces of the cutting edges and an edge area of ​​the unground nitrided surfaces of the cutting edges.

[0091] These sharp edges, which can have a hardness of up to 73 HRC due to the nitriding layer, lead to a significant improvement in the cutting function and the stability of the sharp-edged cutting edges of the cutting tools.

[0092] During operation of the cutting tool, in which the surface of the cutting edges glides over the surface of the perforated disc, material is removed from these cutting edges. However, the large number of opening edge surfaces of the perforated disc with the hard and sharp cutting edges of the openings is suitable for the load-bearing capacity of the cutting tools with their cutting edges and the surrounding base material of the disc in the hardness range of 50 HRC to absorb the resulting friction work by the cutting tools and ensure the function of both cutting tools. The cutting functions of the two sharp edges along the longitudinal extent of each cutting edge are almost completely retained. The material removal on the surfaces of the cutting edges causes the sharp edges of the cutting edges, which have been hardened by the nitriding process, to be regrinded.According to the invention, up to 90% of the surface of the perforated disc is used as a sliding and supporting surface for absorbing the friction force for the knife blade by the bore ring surfaces, which also have a nitriding layer.

[0093] When the nitriding process is used according to the invention with a perforated disc, the entire surface of the perforated disc becomes more stable and harder due to the nitriding layer that forms, particularly in the inner surfaces of the openings. This entire surface of the perforated disc comprises two circular surfaces of the perforated disc, which, regardless of their installation position in the cutting set of the shredding machine, are also referred to here as the top and bottom of the perforated disc. A large number of openings or bores are arranged between the top and bottom of the perforated disc. These openings or bores run from the top of the perforated disc to the bottom of the perforated disc, the parallel sides or circular surfaces of the perforated disc, and thus penetrate the perforated disc completely. Furthermore, the entire surface of the perforated disc also comprises the inner surfaces of the arranged openings or bores.This creates a nitriding layer on the circular surfaces—the top and bottom—of the perforated disc, as well as in the openings or bores of the perforated disc, along the entire length of the openings. This layer makes the perforated disc resistant to bending and wear and tear. The surface also includes an area in the central opening of the perforated disc and an area on the perimeter of the perforated disc.

[0094] In this description, a bore is defined as a straight cylinder-shaped opening in the perforated disc, as is typically created using a drilling tool. Openings in the perforated disc are defined as openings in the perforated disc that deviate at least partially from the shape of a straight cylinder.

[0095] When applying the nitriding process to a cutting tool with multiple cutting edges, at least the surfaces of the cutting edges are made more stable and harder by the formation of the nitriding layer. The grinding of the cutting edges is carried out in such a way that at least part of the resulting nitriding layer is permanently retained as a sharp cutting edge of the cutting edge.

[0096] By using the nitriding process, the hardness of the entire surface, or at least the surfaces of the cutting edges, is increased, with the aim of achieving a Rockwell hardness in the range of 60 HRC to 73 HRC. For comparison, the base material hardness after manufacturing the tool as a standard steel punch disc is approximately 58 HRC.

[0097] When the nitriding layer forms on the entire surface of the perforated disc or cutting tools, nitrogen atoms are also deposited in areas that are further away from the surface. These areas can be 1.0 mm to 3.0 mm from the surface. In these areas too, the hardness of the original material of the perforated disc or cutting tool increases, although this increase decreases with increasing distance from the surface. Depending on the original material, hardness levels in this range from 45 HRC to 58 HRC can be achieved. This means that perforated discs or cutting tools can be manufactured from a material with a lower hardness than is necessary with the state of the art.The inventive application of the nitriding process to the cutting tool, perforated disk, and drive pin produces a hardened surface as well as a hardened region remote from the surface, with the inner regions of the tools retaining their original degree of hardness. Due to the different hardness ranges thus created, the tools produced according to the invention exhibit high stability, low abrasion, and a long service life. A further advantage of these tools produced according to the invention is that the risk of material breakage of the tools, as is known with tools hardened according to the prior art, is minimized by the invention.

[0098] Tool surfaces hardened in this way improve the stability of the rotating cutting tool and its cutting edges. This leads to high-quality processing of the material to be shredded. A further advantage is the processing of large quantities of material and the processing of the material under high pressure in the cutting set. When using state-of-the-art tools, a high proportion of metal abrasion in the material is otherwise to be expected, which is almost completely avoided when applying the solution according to the invention.

[0099] Tool surfaces hardened in this way also improve the stability of the perforated disc, making it more resistant to deflection caused by the pressure of the material being processed against the top of the perforated disc. Reducing the pressure-induced deflection leads to a constant distance between the top of the perforated disc and the cutting edges of the cutting tool. This significantly reduces a performance loss known from the prior art, caused by the distance between the circular surface or top of the perforated disc and the cutting edges becoming at least partially excessive during comminution of the material being processed.

[0100] Tool surfaces hardened in this way also improve the stability of the drive journal. A drive journal according to the invention has a triangular, square, or hexagonal cross-section and is designed with a central cylindrical opening. When the nitriding process is applied to the drive journal according to the invention, the nitriding layer is formed both on its outer surfaces and in the region of the central cylindrical opening in the drive journal. The formation of the nitriding layer in this way on all surfaces of the drive journal leads to increased strength of the drive journal compared to known knife journals from the prior art, which are usually only hardened in partial areas of the tool drive surfaces in which tools are arranged on the knife journal.

[0101] The central cylindrical opening of the drive pin according to the invention is used to attach the drive pin to a driven worm shaft, for example by means of a screw connection. Attached to the worm shaft in this way, the drive pin transmits the rotary motion of the worm shaft to the cutting tools of the cutting set. It has proven advantageous to grind or smooth at least part of the nitriding layer formed on the upper side of the perforated disc, the surface of which is rough, in order to reduce the roughness of the surface of the perforated disc by 50%. This creates a sliding layer on the circular surface or upper side of the perforated disc, which improves the sliding of the cutting edges of the cutting tool over the upper side of the perforated disc and reduces material abrasion.The cutting edges of the cutting tool slide with their cutting surfaces described above over the top of the perforated disc.

[0102] As already explained, the surfaces of the cutting edges of the cutting tool that are provided with a nitriding layer are also ground in order to improve cutting conditions when the cutting tool and the perforated disc slide against each other.

[0103] In the perforated discs, the circular surfaces of the openings, which are coated with a nitriding layer, absorb approximately 90% of the contact forces of the cutting tool's cutting edges. Even if material is removed from the top surface of the perforated disc, where the nitriding layer is no longer present in the areas between the circular surfaces, the comminution properties of the material being processed are not impaired. Such material removal leads to regrinding of the edges of the circular surfaces of the openings, which are robust thanks to the nitriding layer, and to consistently high comminution quality of the material being processed.

[0104] The circular surfaces of the openings have a hardness in the range of, for example, 70 HRC, while the areas between the circular surfaces, in which there is no longer any nitriding layer, have a hardness of, for example, only about 50 HRC.

[0105] A special embodiment of the invention is that the perforated disc or a pre-cutter of the cutting set is manufactured by means of a 3D printing process.

[0106] In addition to known metal processing techniques for the production of tools such as a perforated disc or a cutting set with its cutting edges for a cutting set of a shredding machine, it is planned to produce these tools, in particular the perforated disc with its openings, using a 3D printing process.

[0107] The use of a 3D printing process to produce the perforated disc makes it possible to create or manufacture the disc with the appropriate openings in 3D printing. This eliminates the need for subsequent insertion of openings, such as holes, as is the case with the current technology.

[0108] A particular advantage of using a 3D printing process to produce the perforated disc is that special openings with a non-rectilinear course can be produced together with the disc.

[0109] A variant of such a non-linear pattern is an opening that is, for example, designed in two parts. Such openings can be produced in a single production step using 3D printing. In one embodiment, the opening comprises two adjacent sections located one behind the other within the opening, which together form the opening. This opening runs from the top side of the perforated disc to the opposite bottom side of the perforated disc, thus completely penetrating the perforated disc.

[0110] The first sub-region is in the form of an oblique cylinder and the second sub-region adjoining the first sub-region in the opening is in the form of a straight cylinder. The longitudinal axis of the first sub-region runs at an angle of between 20 degrees and 40 degrees to the top side of the perforated disc, while the longitudinal axis of the second sub-region runs at a right angle to the opposite underside of the perforated disc. The 3D printing process naturally enables other designs of the openings, which, for example, consist of more than two sub-regions. Furthermore, sub-regions can also be produced using 3D printing which are not cylindrical. Likewise, sub-regions of the opening or the entire opening can have a non-rectilinear course, in particular a course curved within a predetermined radius.One advantage of arranging a first section, for example in the form of an inclined cylinder, on the top side of the perforated disc, over which the cutting edges of the cutting tool slide, is that a nearly semicircular cutting edge and intake edge of the opening are formed on the top side of the perforated disc. This edge is formed at an angle of less than 90 degrees, i.e., at an acute angle, thus improving the comminution of the material being processed and the disc's performance. This advantage impacts both the quality and the processed quantity.

[0111] The 3D printing process can also be used to produce a cutting tool with its cutting edges. In this case, too, the cutting tool is subsequently hardened using the nitriding process and, depending on the type, is then adapted to the function of the tool and its shape as a common tool element by means of post-processing with a grind.

[0112] It is further provided that the nitriding process is carried out at a temperature between 500 °C and 590 °C and for a duration of between 50 h and 70 h or with the tools of the cutting set, which have been manufactured by means of a 3D printing process, at a temperature between 500 °C and 600 °C and for a duration of between 20 h and 40 h.

[0113] Using these selected parameters for temperature and treatment time when performing the nitriding process with tools from the cutting set manufactured using a 3D printing process, such as a perforated disc, a cutting set, or a drive pin, results in a layer thickness in a range between 0.1 mm and 0.7 mm, in particular a layer thickness of 0.5 mm. For example, by specifically controlling the treatment time, a specified layer thickness can be precisely achieved.

[0114] For example, for a tool made of steel in the usual way, such as a perforated disc, the treatment time in the nitriding process at temperatures between 500 °C and 590 °C is about 50 h to 70 h.

[0115] In contrast, the treatment time of a perforated disc produced using a steel powder in a 3D process at temperatures between 500 °C and 600 °C is only about 20 to 40 hours, which is a further advantage of using the 3D printing process.

[0116] A steel commonly used to manufacture tools such as the cutting tool and / or the perforated disc can, for example, be designated 1.7225 or 42CrMoV4, 1.4034 or 1.2842.

[0117] 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:

[0118] Fig. 1 : several representations of examples of support crosses from the

[0119] State of the art,

[0120] Fig. 2: Examples of replaceable bushings or separate bearings according to the state of the art,

[0121] Fig. 3: a process of uneven loading of the transport and working screw due to a force acting perpendicular to the longitudinal axis,

[0122] Fig. 4: a sectional view showing the effect of the bending of the worm shaft and the knife pin on a first cutting tool,

[0123] Fig. 5: a first cutting tool according to the invention with a first hollow cylindrical collar,

[0124] Fig. 6: a representation of the cutting tools according to the invention as well as other components arranged in the cutting set of the shredding machine,

[0125] Fig. 7: a second cutting tool according to the invention,

[0126] Fig. 8: a perspective view of the first cutting tool and the second cutting tool, arranged on the drive pin,

[0127] Fig. 9: a sectional view of the components of the cutting set of the

[0128] Shredding machine, Fig. 10a to 10d: various representations of an exemplary drive pin according to the invention in a comparison with representations of a knife pin from the prior art, Fig. 11a and 11b: a perforated disc from the cutting set and

[0129] Fig. 12: a diagram of the result of the production of the nitriding layer with 75 HRC on an example of a perforated disc.

[0130] Figure 1 shows several representations of examples of support crosses from the state of the art.

[0131] Figure 2 shows examples of replaceable bushings or separate bearings according to the state of the art.

[0132] As examples of the use of replaceable bushings or separate bearings according to the state of the art, Figure 2 shows, for example, a replaceable bearing in an installed state and in a removed state, a ball bearing and a pressed-in bushing as a bearing of a cutting tool or pre-cutter.

[0133] Figure 3 shows a process of uneven loading of the transport and working screw 1 due to a force 3 acting perpendicular to the longitudinal axis 2 of the transport and working screw 1 according to the prior art.

[0134] The process of uneven loading of the transport and working screw 1 due to a force 3 acting perpendicular to the longitudinal axis 2 of, for example, approximately 57 kN, coupled with insufficient absorption of the resulting tilting forces, is shown in Figure 3. The force 3 acting perpendicular to the longitudinal axis 2 arises when the raw material is drawn in in the open hopper and presses the processed material into narrow screw flights in the closed housing.

[0135] In the example of Figure 3, the transport and working screw 1 is mounted at points A and B, which represent the bearing points of the transport and working screw 1. The force 3 acting perpendicular to the longitudinal axis 2 causes a deflection or bending 4 of the transport and working screw 1 away from the longitudinal axis 2. This bending 4 affects both the transport and working screw 1 and the knife pin 5 known from the prior art, as shown in Figure 3.

[0136] Figure 4 shows a sectional view of the effect of the bending 4 of the knife pin 5 on a first cutting tool 6 according to the prior art. In the example in Figure 4, the first cutting tool 6 is shown without the knife pin 5. The angle alpha shown illustrates the effect of the bending 4 on the first cutting tool 6.

[0137] As a result of the bending 4, the rotating first cutting tool 6 arranged between two stationary perforated discs 7 is inclined in the cutting plane shown.

[0138] Wear or material removal occurs at so-called contact points 8, which form between the cutting tool 6 and the adjacent perforated disks 7. The wear affects both the perforated disks 7 and the first cutting tool 6, in particular the cutting edges 9 arranged on the first cutting tool 6, which are not shown in Figure 4. While the contact points 8 form on one side of the first cutting tool 6, a distance 10 between a surface of the perforated disk 7 and the first cutting tool 6 increases at the positions opposite the contact points 8. This distance 10 leads to a deterioration in the quality of the comminution of the processing material (not shown) in these areas.

[0139] Figure 5 shows a first cutting tool 6 according to the invention with a first hollow cylindrical collar 11 and differently positioned cutting edges 9 and 34.

[0140] Shown is the first cutting tool 6, also referred to as the main cutting tool, as well as a hollow-cylindrical first collar 11 according to the invention, which is arranged on one side of the first cutting tool 6 and, in the nitrided state, is used as a bearing element in the cutting set. Furthermore, four cutting edges 9 arranged on the first cutting tool 6 are shown, along with their cutting edges. These cutting edges, formed in a longitudinal direction of the cutting edges 9, are used to comminute the material to be processed in the cutting set of the comminution machine in cooperation with a perforated disc 7 (not shown) and its openings 12.

[0141] The hollow-cylindrical first collar 11 is made of the same material as the base body of the first cutting tool 6. A first length 13 of the first hollow-cylindrical collar 11 formed on the first cutting tool 6 and protruding from the cutting tool 6 on one side corresponds to a thickness of a perforated disc 7 (not shown). This refers to a maximum thickness of the perforated disc 7. Alternatively, a thickness or depth of a bearing bush of the perforated disc 7 in the direction of a rotational axis of the first cutting tool 6, on which the perforated disc 7 is arranged, is referred to.

[0142] The first hollow-cylindrical collar 11 and the first cutting tool 6 form a central opening 14. This continuous central opening 14 has a shape or inner contour that is adapted to a shape or outer contour of a drive pin 15 according to the invention (not shown) or is designed to correspond thereto.

[0143] Corresponding refers to a match with respect to an inner diameter or outer diameter, a shape, for example, two-edged, triangular, square, hexagonal, as well as special formations 16. The drive pin 15 according to the invention and the unit consisting of the first collar 11 and the first cutting tool 6 with the common central opening 14 must have these matches in order to enable a positive connection of the components. Thus, the first cutting tool 6 with its first hollow-cylindrical collar 11 can be arranged on the drive pin 15 according to the invention in a positive-fitting and torsion-free manner.

[0144] This positive connection results in a fixed alignment between the cutting edges 9 of the rotating cutting tool 6 and a position of the rotating transport and working screw 1. The first hollow-cylindrical collar 11 has a wall thickness 17 between its inner diameter and its outer diameter, which ranges between 5 mm and 10 mm. The wall thickness 17 is based on a load-bearing length and the thickness of the disc to be mounted on the collar 11, such as the perforated disc 7.

[0145] The first hollow-cylindrical collar 11 formed on the rotating first cutting tool 6 is intended to form a nitriding-hardened bearing surface or a plain bearing for a tool of the comminution machine arranged adjacent to the first cutting tool 6, such as the perforated disc 7. For this purpose, the perforated disc 7 is arranged on the outer surface of the first hollow-cylindrical collar 11, as will be shown later. According to the method, the first cutting tool 6 with its first hollow-cylindrical collar 11 is provided with a nitriding layer on its surfaces, which significantly improves the hardness of the tool and thus also the bearing properties of the first hollow-cylindrical collar 11.

[0146] Figure 5 shows an enlarged view of another cutting edge 34, which is arranged adjacent to the cutting edge 9. The four half-acting cutting edges 34 arranged on the first cutting tool 6 serve to divide the large-sized processing material fed from the transport and processing screw 1 and reduce the size of the pre-divided pieces of the processing material conveyed out by a pre-cutter (not shown). This reduces the chunkiness of the cutting set and increases the processing performance.

[0147] Figure 6 shows a representation of the cutting tools 6 and 18 according to the invention as well as other components arranged in the cutting set of the shredding machine.

[0148] In addition to the first cutting tool 6 already shown in Figure 5, Figure 6 shows a further second cutting tool 18 according to the invention. The second cutting tool 18, which is also referred to as a pre-cutting tool, has a hollow-cylindrical second collar 19 according to the invention, which is arranged on one side of the second cutting tool 18. Furthermore, four cutting edges 9 arranged on the second cutting tool 18 are shown with their cutting edges. By means of these cutting edges, which are formed in a longitudinal direction of the cutting edges 9, the pre-shredding of the material to be processed takes place in the cutting set of the shredding machine in cooperation with a pre-cutter 20 shown next to the second cutting tool 18 in Figure 6.The task of the second cutting tool 18 with its cutting edges 9 is to pre-shred the material to be processed and thus to support the processing performance of the subsequent first cutting tool 6.

[0149] The second hollow cylindrical collar 19 consists of the same material as the base body of the second cutting tool 18. A second length 21 of the second hollow cylindrical collar 19 formed on the second cutting tool 18 and protruding from the cutting tool 18 on one side corresponds to a thickness of the pre-cutter 20. This refers to a maximum thickness of the pre-cutter 20 or a depth of a bearing bush of the pre-cutter 20 in the direction of a rotation axis of the second cutting tool 18, on which the pre-cutter 20 is arranged.

[0150] The second hollow-cylindrical collar 19 and the second cutting tool 18 form a second central opening 22. This continuous second central opening 22 has a shape or inner contour that is adapted to the shape or outer contour of the drive pin 15 according to the invention or is designed to correspond thereto, as can be seen in Figure 6. In the example, the second central opening 22 and the drive pin 15 are hexagonal. The opening 22 also has a recess 16 that corresponds to a groove 23 formed in the drive pin 15. This groove 23 ensures a defined knife position relative to the conveying points of the transport and working screw 1 for transferring the raw material to the cutting set.

[0151] In the example, the drive pin 15 according to the invention has a hexagonal profile, which results in at least 30% higher and consistent power transmission simultaneously across all edges of the drive pin 15 according to the invention compared to prior art knife pins 5. A further means of improving power transmission is the groove 23 in the drive pin 15, in which the recess 16 of the first cutting tool 6 and the recess 16 of the second cutting tool 18 are positioned or arranged. This ensures the necessary position between the screw geometry at the end of the transport and working screw 1 (not shown) for transferring the conveyed material to the cutting tools 6 and 18 without disruption or loss of thrust.

[0152] When assembling the cutting set of the shredding machine, the perforated disc 7 is pushed onto the first hollow-cylindrical collar 11 of the first cutting tool 6, as shown in Figure 6 by two arrows. The perforated disc 7, which has a plurality of openings 12, is arranged after assembly with an inner surface 24 slidingly mounted on an outer surface 25 of the first hollow-cylindrical collar 11. The inner surface 24 and the outer surface 25 have a nitriding layer on their surfaces, which makes the surfaces 24 and 25 harder and reduces wear.

[0153] Furthermore, during this assembly, the pre-cutter 20 is pushed onto the second hollow-cylindrical collar 19 of the second cutting tool 18. After this assembly, the pre-cutter 20 is arranged with an inner surface 26 slidingly mounted on an outer surface 27 of the second hollow-cylindrical collar 19.

[0154] In Figure 6, three further arrows show the directions of rotation of the drive pin 15 according to the invention and of the cutting tools 6 and 18 driven by the drive pin 15 in the cutting set of the shredding machine.

[0155] After assembly, according to the invention, a first sliding bearing is formed between the outer surface 25 of the first hollow-cylindrical collar 11 and the inner surface 24 of a central opening in the perforated disk 7. Furthermore, according to the invention, a second sliding bearing is formed between the outer surface 27 of the second hollow-cylindrical collar 19 and the inner surface 26 of a central opening in the pre-cutter 20. The first sliding bearing and the second sliding bearing are also referred to as nitrided-layer sliding bearings according to the invention. Figure 7 shows a second cutting tool 18 according to the invention.

[0156] The second cutting tool 18 according to the invention is shown with its second hollow-cylindrical collar 19. The central inner diameter of the second hollow-cylindrical collar 19 is also designed to correspond to the hexagonal profile of the drive pin 15, which is not shown in Figure 7. The second cutting tool 18 has a recess 16 for maintaining the position relative to the transport and working screw 1, for the defined knife position relative to the conveying points of the transport and working screw 1 for the raw material transfer to the cutting set, and four cutting edges 9.

[0157] Figure 8 shows a perspective view of the first cutting tool 6 and the second cutting tool 18, arranged on the drive pin 15 in a position-secured bearing function.

[0158] In Figure 8, the first cutting tool 6 and the second cutting tool 18 are shown pushed onto the drive pin 15 according to the invention. Due to the design of the openings 14 and 22 and the corresponding hexagonal outer profile of the drive pin 15, the cutting tools 6 and 18 are arranged on the drive pin 15 in a form-fitting and rotationally secure manner. A rotational movement of the drive pin 15 is thus transmitted to the cutting tools 6 and 18. For this purpose, the drive pin 15 is force-coupled to a worm shaft on which the transport and working worm 1 is arranged, for example by means of screw connections and key elements, for the purpose of power transfer.

[0159] Figure 9 shows a sectional view of the components of the cutting set of the shredding machine.

[0160] The first cutting tool 6 and the second cutting tool 18 are arranged on the drive pin 15. The perforated disc 7 is arranged on the first hollow-cylindrical collar 11. The first sliding bearing according to the invention is formed between the inner surface 24 of the perforated disc 7 and the outer surface 25 of the first hollow-cylindrical collar 11. Furthermore, the first sliding bearing according to the invention is formed between the inner surface 26 of the pre-cutter 20 and the outer surface 27 of the second hollow-cylindrical collar 19. The drive pin 15 according to the invention has a central, elongated cylindrical opening 33. This central cylindrical opening 33 is used to attach the drive pin 15 to a driven worm shaft, for example by means of a screw connection, which is not shown in Figure 9.This creates a component connection between the shaft of the transport and working screw 1 and the drive pin 15, which achieves a better force distribution between the two components and increases stability. Attached to the screw shaft in this way, the drive pin 15 transmits the rotational movement of the screw shaft to the cutting tools 6 and 18 of the cutting set.

[0161] Figures 10a to 10d show various representations of an exemplary drive pin 15 according to the invention with a cylindrical opening 33 such as a through-bore in a comparison with representations of a knife pin 5 from the prior art.

[0162] The drive pin 15 according to the invention has a first partial region 28 and a second partial region 29, as shown in Figure 10a. The first partial region 28 is substantially cylindrical with a cylindrical round key 30 for force transmission and positional securing for the alignment of the cutting edges 9 of the cutting tools 6 and 18 relative to a position of the transport and work screw 1. This first partial region 28 is arranged at one end or flight end of the transport and work screw 1 and tightened with a clamping screw, whereby the rotational movement of the transport and work screw 1 is transmitted to the cutting tools 6 and 18.

[0163] The transport and working screw 1 as well as the cutting tools 6 and 18 are not shown in Figures 10a to 10d.

[0164] To reliably transmit the rotary motion of the transport and working screw 1 to the drive pin 15, the drive pin 15 has, in its first section 28, a means 30 for the most torsion-free arrangement of the drive pin 15 in the transport and working screw 1. The means 30 is designed, for example, in the form of a wedge or a key 30. The second section 29 is essentially designed with a hexagonal profile and a groove 23. The first cutting tool 6 with the first collar 11 and the second cutting tool 18 with the second collar 19 are placed and fixed onto this hexagonal profile.

[0165] The drive pin 15 has a nitriding layer in the first partial area 28, the second partial area 29, and the cylindrical opening 33, which increases the stability of the drive pin 15. This process only slightly alters the overall strength of the drive pin 15, while retaining particularly advantageous features of the drive pin 15 with regard to its fracture behavior. The shaft strength of the drive pin 15 is increased by adjusting the internal force distribution. Furthermore, the drive pin 15 is additionally stabilized against deformation and / or deflection or bending.

[0166] The knife pin 5 shown in Figure 10b from the prior art is designed with two edges in a known manner.

[0167] Figures 10c and 10d also show a comparison of the profiles of the knife pin 5 and the drive pin 15.

[0168] Figures 11a and 11b show a perforated disk 7 from the cutting set, which is arranged on the first hollow-cylindrical collar 11 of the first cutting tool 6 (not shown in Figures 11a and 11b). Figure 11a shows the perforated disk 7 in a perspective view, while Figure 11b shows the perforated disk 7 in a sectional view. The perforated disk 7 is arranged with its inner surface 24, forming a nitrided-layer sliding bearing, on the outer surface 25 of the first hollow-cylindrical collar 11, which is provided with a nitrided layer, which is also not shown in Figures 11a and 11b.

[0169] By applying the nitriding process, a superficial nitriding layer is formed on the entire surface of the perforated disc 7, for example, with a layer thickness of 0.2 mm to 0.5 mm, depending on the duration of the nitriding process, also over the entire length of the inner walls of the openings 12. The Rockwell hardness of this formed nitriding layer is in the range of 60 HRC to 75 HRC. In the outer region of the nitriding layer, the nitrogen is anchored in the structure of the base material, thus increasing its hardness in limited layers to 50 HRC. This makes the entire disc consistently stable in its surface and thickness.

[0170] The nitriding layer is formed on the entire surface or all partial surfaces of the perforated disc 7. The entire surface comprises the circular top and bottom of the perforated disc 7, wherein a plurality of openings 12 are arranged in these. Furthermore, the entire surface of the perforated disc 7 also comprises the inner surfaces of the arranged openings 12. Thus, a nitriding layer is created near the surface both on the top and bottom of the perforated disc as well as in the openings or bores of the perforated disc 7, which makes the perforated disc 7 stable against bending and wear-resistant against abrasion. The nitriding layer is also created on the surface of the central bore of the perforated disc 7, i.e., on the inner surface 24 of the perforated disc 7.

[0171] Figure 11b shows a cross-sectional view of the perforated disc 7, taken along section line AA in Figure 11a. As can be seen, the nitriding layer is also formed on the walls of the openings 12, forming regions 31 with increased strength or hardness. These regions 31 are, for example, 0.2 mm to 0.5 mm thick and have a hardness in the range of 70 HRC to 73 HRC.

[0172] The remaining material of the perforated disc 7 represents an area 32 with a normal material-related basic strength or hardness. This means that the areas 32 have a degree of hardness which corresponds to the material used for the perforated disc 7, such as a tool steel 1.7225 / 42CrMo4 with a hardness of 58 HRC. Such degrees of hardness are achieved in normal hardening processes known from the prior art. During the formation of the nitriding layer on the entire surface of the perforated disc, nitrogen atoms are also deposited in areas which are further away from the surface. These areas can be 1.0 mm to 3.0 mm from the surface. The hardness of the original material also increases in these areas, although this increase decreases with increasing distance from the surface.Depending on the original material, hardness levels in this range from 45 HRC to 58 HRC can be achieved.

[0173] Thus, areas 31 and 32 alternate in the sectional view of the perforated disk 7, as can be seen in Figure 11b. This combination of areas 31 and 32 simultaneously ensures that the running surfaces for the cutting edges 9, for example of the cutting tool 6, have a very good surface shape with low friction values, and that this is maintained across the entire thickness of the perforated disk 7 even during regrinding. This also leads to improved rigidity of the perforated disk 7, particularly against deflections and vibrations resulting from the frequent changes between different material states of the processed material, which do not allow for a uniform force distribution but cause an unsteady force distribution. This combination also leads to an improvement in the stability of the cutting edges of the openings 12 and to less material abrasion on the circular surface or upper side of the perforated disk 7.

[0174] Figure 12 shows a diagram showing the result of the production of the nitriding layer with 73 HRC using an example of a perforated disk 7.

[0175] In particular, the result of the production of the nitriding layer with 73 HRC and the hardness increases in the surrounding profile of the microstructure of the soft base material and the resulting effective depth are shown using an example of a perforated disc 7.

[0176] Figure 12 does not show the nitriding layer, but rather an increase in hardness in the surrounding profile of the microstructure of the soft base material as a result of a nitriding process in which nitrogen is absorbed into the microstructure of the soft unhardened material.

[0177] The diagram shows an increase in the hardness of the material, or rather the base material, particularly within a range of approximately 0.3 mm from the surface of the perforated disc 7. Only the parameters of the base material directly in contact with the nitriding layer were measured, thus demonstrating the hardness profile and distribution beneath the nitriding layer across the disc thickness. A low-load test die was used during the test to measure only the hardness within the thin layer.

[0178] The recorded hardness parameters refer to the steel of the base material, designated 1.7225 or 42CrMoV4. The incorporation of nitrogen atoms into the microstructure of the base material directly adjacent to the nitriding layer increases its hardness. This was measured with considerable effort and demonstrated in Figure 12.

[0179] This shows that in addition to the high hardness values ​​of the nitriding layer in a range up to 73 HRC, strength states also arise in the material which can additionally absorb large forces.

[0180] List of reference symbols

[0181] 1 transport and working screw

[0182] 2 Longitudinal axis

[0183] 3 Force

[0184] 4 Bending

[0185] 5 knife pins according to the state of the art

[0186] 6 first cutting tool

[0187] 7 hole disc

[0188] 8 Contact point

[0189] 9 cutting edge

[0190] 10 distance

[0191] 11 first hollow cylindrical collar

[0192] 12 openings in the perforated disc

[0193] 13 first length

[0194] 14 first central opening of the first cutting tool

[0195] 15 drive pins

[0196] 16 Formation

[0197] 17 wall thickness

[0198] 18 second cutting tool

[0199] 19 second hollow cylindrical collar

[0200] 20 pre-cutters

[0201] 21 second length

[0202] 22 further central opening of the second cutting tool

[0203] 23 grooves

[0204] 24 Inner surface of the perforated disc

[0205] 25 first outer surface / bearing surface of the first hollow cylindrical collar

[0206] 26 Inner surface of the pre-cutter

[0207] 27 second outer surface / bearing surface of the second hollow cylindrical collar

[0208] 28 first section of the drive pin

[0209] 29 second part of the drive pin key area of ​​increased strength / hardness area of ​​normal strength / hardness cylindrical opening further cutting edge

Claims

Patent claims 1 . Cutting set for a shredding machine, wherein at least a first cutting tool (6), a perforated disc (7) and a drive pin (15) are arranged in the cutting set, characterized in that a first hollow cylindrical collar (11) is arranged on the first cutting tool (7) of the cutting set.

2. Cutting set according to claim 1, characterized in that a second hollow cylindrical collar (19) is arranged on a second cutting tool (18) of the cutting set.

3. Cutting set according to claim 1 or 2, characterized in that the first hollow cylindrical collar (11) has a first length (13) which corresponds to a thickness of the perforated disc (7) or that the second hollow cylindrical collar (19) has a second length (21) which corresponds to a thickness of a pre-cutter (20).

4. Cutting set according to claim 1 or 2, characterized in that the first hollow cylindrical collar (11) has a first length (13) which corresponds to a thickness of the perforated disc (7) and that the second hollow cylindrical collar (19) has a second length (21) which corresponds to a thickness of a pre-cutter (20).

5. Cutting set according to one of claims 1 to 4, characterized in that the hollow cylindrical collar (11, 19) has a two-edged, triangular, square or hexagonal inner diameter and a second partial area (29) of the drive pin (15) has a hollow cylindrical Collar (11, 19) has a corresponding two-edged, triangular, square or hexagonal outer diameter.

6. Cutting set according to one of claims 1 to 5, characterized in that a first bearing surface (25) is formed on the first hollow cylindrical collar (11), on which the perforated disc (7) rests with its inner surface. before (26) is arranged, and that a second bearing surface (27) is formed on the second hollow cylindrical collar (19), on which the pre-cutter (20) is arranged with its inner surface (26).

7. Cutting set according to one of claims 1 to 6, characterized in that the first cutting tool (6) with its first hollow cylindrical collar (11) or the second cutting tool (18) with its second hollow cylindrical collar (19) is arranged in a twisted manner on the drive pin (15) of the shredding machine, wherein the drive pin (15) is arranged on a driven transport and working screw (1) of the shredding machine.

8. Cutting set according to one of claims 1 to 6, characterized in that the first cutting tool (6) with its first hollow cylindrical collar (11) and the second cutting tool (18) with its second hollow cylindrical collar (19) are arranged in a twisted manner on the drive pin (15) of the shredding machine, wherein the drive pin (15) is arranged on a driven transport and working screw (1) of the shredding machine.

9. Cutting set according to one of claims 1 to 8, characterized in that openings (12) in the perforated disc (7) are rectilinear bores, wherein a longitudinal axis of the rectilinear bore is aligned at right angles to a circular surface or upper side of the perforated disc (7), or that the openings (12) in the perforated disc (7) each have a course with two partial areas, wherein the first partial area is designed in the form of an oblique cylinder, the longitudinal axis of which is aligned at an angle between 20 degrees and 40 degrees, in particular at an angle between 20 degrees and 30 degrees, especially at an angle of 25 degrees, to the circular surface or upper side of the perforated disc (7), and wherein the second partial area adjoining the first partial area in the opening (12) is designed in the form of a straight cylinder,whose longitudinal axis is perpendicular to the circular surface or top of the perforated disc (7).

10. Cutting set according to one of claims 1 to 9, characterized in that a central cylindrical opening (33) is arranged in the drive pin (15).

11. A method for producing a cutting set according to claims 1 to 10, in which at least one first cutting tool (6) with a plurality of cutting edges (9), a perforated disc (7) with openings (12) and a drive pin (15) are provided as tools of the cutting set of a comminution machine, characterized in that an entire surface of the perforated disc (7) is hardened by means of a nitriding process after production of this tool, a Rockwell hardness in a range of 70 HRC to 73 HRC being produced on this surface.

12. Method according to claim 11, characterized in that surfaces of the cutting edges (9) of the cutting tool (6, 18) are hardened by means of a nitriding process after production of this tool.

13. Method according to claim 11 or 12, characterized in that surfaces of the drive pin (15) are hardened by means of a nitriding process after production of this tool.

14. Method according to one of claims 11 to 13, characterized in that the perforated disc (7) or a pre-cutter (20) of the cutting set is produced by means of a 3D printing process.

15. The method according to any one of claims 11 to 14, characterized in that the nitriding process is carried out at a temperature between 500 °C to 590 °C and for a time period between 50 h to 70 h or with the tools of the cutting set, which have been produced by means of a 3D printing process, at a temperature between 500 °C to 600 °C and for a time period between 20 h to 40 h.

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