Device and method for conveying and for comminuting materials for processing

Abstract

The invention relates to a device (1) and a method for conveying and for comminuting materials for processing, and is based on the problem of specifying a solution which allows targeted, gentle and high-quality comminution of a material for processing, in particular of a material for processing which is of animal or plant origin, even in a deep-frozen state, with a level of reliability of the device (1) being increased and a service life of the device (1) and the effectiveness thereof being improved. Said object is achieved in terms of an arrangement in that the device (1) has a housing (2), non-blocking conveying screws (11) which rotate in pairs at a rotational speed n1, blocking conveying screws (13) which rotate in pairs at a rotational speed n2, at least one non-blocking pre-comminution screw (20) which rotates at a rotational speed n3, a pressure sensor (23) which is arranged in a pre-comminution region (7) and which serves for determining a working pressure of the material for processing in the pre-comminution region (7), and a cutting region (8) having a cutting unit (24) for comminuting the material for processing.

Description

[0001] Device and method for conveying and comminuting processed materials

[0002] The invention relates to a device for conveying and comminuting processed materials. The invention also relates to a method for conveying and comminuting processed materials in a device for conveying and comminuting processed materials.

[0003] The invention relates to a device for conveying and comminuting processed goods of animal or plant origin in a device having a plurality of conveyor screws for transporting the processed goods in the direction of a cutting unit by means of which the processed goods are comminuted, as well as to a method for comminuting a processed goods in such a device.

[0004] Processed goods are defined below as food of plant or animal origin such as meat, cheese, fat, fish, skin, bones and other components of food.

[0005] For comminution of processed material, particularly in the meat industry, so-called grinders are typically used as devices for comminution. The so-called thrust force for transporting the processed material in such a device is generated through the interaction of a screw, the processed material (as the force transmitter), and a screw housing equipped with support elements. The achievable thrust force is achieved through the material strength and the various states of force transmission.

[0006] Such devices for comminuting a material to be processed 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 with cutting tools, for example consisting of perforated discs and rotating knives, is arranged at the second end of the conveyor screw.

[0007] The at least one conveyor screw used generally works in such a way that pressure is built up between the conveyor screw rotating within the conveyor housing and the conveyor housing through a mass feed, whereby the food to be chopped is conveyed in a conveying direction along a conveyor screw axis. Such conveyor screws have an efficiency of 30% to 50%, which means that 50% to 70% of the conveyed processed material is adversely destroyed due to the crushing resistance of the tools and the resulting back pressure, particularly in front of the cutting unit, in the edge areas of the conveyor screw. With a loss of strength, the material flows back alongside the conveyor screw against the conveying direction. Thrust-pressure losses arise due to the structural change in the material strength of the material being conveyed during power transmission.

[0008] The state of the art assumes that a so-called thrust pressure is generated in an area in front of the cutting unit by the at least one conveyor screw used and thus represents the causal prerequisite for an achievable throughput of the device for comminuting a processing material or of the grinding machine.

[0009] It is assumed that the penetration of the material into the openings of a perforated disc of the cutting unit as so-called meat plugs is only pressure-dependent and is directly related to the arrangement of the openings on the perforated disc of the cutting unit.

[0010] Therefore, according to the state of the art, pressure-increasing single-flight screw conveyors with a screw chamber volume decreasing towards the cutting unit are preferred.

[0011] In many state-of-the-art grinders, the rotational movement of the conveyor screw is transmitted to the rotating knives or cutting tools via a connected knife pin, thereby driving them. This is achieved, for example, in the device described in DE 10 2011 008 389 A1. The food to be minced is pushed along support and holding elements within the conveyor housing by the rotating screws toward the cutting tools. By means of the last screw flight of the conveyor screw, which is open there, the product is then pressed into the openings of a perforated disk by the effective open flight pitch opposite the tool system and secured there.The necessary thrust results from the pressure built up between the screw conveyor and the conveyor housing due to the material being processed, which acts analogously to a chain, V-belt, or gear. A layer of material being processed, formed on the edge of the screw conveyor and on the housing's support elements, acts primarily as the force-transmitting element. The resulting thrust is then responsible for at least partially pressing the material being processed into the openings of the perforated disc. The rotating blade, driven by the rotating screw conveyor, cuts the material being pressed into the openings of the perforated disc, thereby chopping it into pieces.In this case, several rotating knives and perforated discs are often arranged in succession in order to achieve a gradual comminution of the material being processed with decreasing material strength and increasing performance with smaller openings.

[0012] In addition to devices for purely comminuting a product, devices that also serve as filling devices are also known in the art. Using such filling devices, ready-to-use mixtures of processed products with a grain size of, for example, 8-13 mm can be finally ground and filled into casings, for example, as finished sausage meat. Filling devices are generally not used to process large cuts of meat.

[0013] For some applications, screw conveyors are also used in which the conveyor is made up of sections of so-called blocking screws and sections of non-blocking screws. The different sections can be made of two different materials or of a single material. The screw body is essentially a rigidly connected unit, with the turns of the screw conveyor being designed differently in different sections. Typically, the screw conveyors are designed as non-blocking screws in the section designed to feed the processed material and then transition to a blocking screw design in the conveying direction of the processed material.The screw conveyors operate like a displacement system with almost 100% efficiency, without losing any material transported in the conveying direction due to backflow in the peripheral areas between the screw conveyor and the conveyor housing. Furthermore, such screw conveyors have the advantage that the energy required to operate such a device for comminuting a material can be reduced by 70% to 80%.

[0014] A disadvantage of such screw conveyors is that, due to the high conveying rate and the gentle transport required, they cannot process deep-frozen products. When using screw conveyors for deep-frozen products, the cold, particularly at very low temperatures below -10°C, causes the product to solidify in the area in front of the cutting unit. This disadvantageously prevents or even completely blocks the material from being pressed into the openings and thus from being shredded. Using such devices, which use screw conveyors for transport to the cutting unit, it is therefore not possible to process deep-frozen, granulated, or small-piece products, and certainly not larger, deep-frozen blocks of food.

[0015] The reason for this is that the gentle conveying of the material does not place any mechanical stress on it, preventing any loosening of the structure and thus maintaining its temperature-dependent, multiply increased strength. This makes it virtually impossible for the material to form cones due to deformation in the openings of a perforated disc in the cutting unit. The stress-free conveying thus ensures that the material retains its rigidity and cannot be processed accordingly, even with upstream granulation, i.e., pre-shredding.The thrust energy, which in the case of soft processing material ensures that the processing material is pressed into the openings of the perforated disc, leads in the case of deep-frozen processing material to the processing material being compressed in the area immediately in front of the cutting unit and the formation of cones in the openings of the perforated disc is not possible.

[0016] Since temperatures of the processed product in the range of -18 °C are common, especially when processing meat products, these cannot be processed in such devices, especially in conjunction with perforated discs which have openings in the fine disc range of 2.0 mm to 8.0 mm in diameter.

[0017] Meat is understood to be a natural, highly stable, organic, multi-component system of living organisms composed of muscle cells, fat, and collagen tissue, organized according to their vital functions, which is processed or prepared for human consumption. It is a muscle protein structured within an aqueous matrix and contains a multitude of collagen sheaths and intermediate layers for the muscle groups, which radiate into force-transmitting tendons and have embedded and superimposed fatty tissue. The water content, around 75% of lean meat, is more or less firmly attached to protein molecules within the muscle fibers and is not freely movable. In its dismembered state, i.e. removed from the bone, meat is processed at temperatures between -1.5°C and +7°C and is mechanically highly resilient, with elastic properties, but with poor external shape retention.As a material subjected to compressive stress, it exhibits high deformation and strength properties due to its functionally arranged properties in the flesh part, which protect against internal structural damage. These special features must be taken into account during processing.

[0018] To improve the processing of food,

[0019] DE 10 2017 003 406 B4 proposes a device that automatically adjusts the pressure on the food immediately before shredding. This is achieved by means of cutting openings arranged radially from the conveyor screw. However, this device has the major disadvantage of being very maintenance-intensive. For example, a quick change to different hole sizes, as proposed in DE 20 2006 001 840 U1, is not possible.

[0020] A further disadvantage of the known prior art is that, due to the one-sided feed of the processing material into the non-blocking screw conveyors in the receiving area, high deformation forces occur on the screws when the raw material is drawn from the hopper into the non-blocking screw conveyors. As a result, the one-sidedly mounted, non-blocking screw conveyors bend or are pushed or bent out of the center of travel or away from their respective longitudinal axes. This displacement or canting of the non-blocking screw conveyors in the receiving area from their center of travel not only affects the non-blocking screw conveyors themselves. It leads to frictional wear between the screws and the housing of the device and, consequently, to increased backflow of the conveyed material with simultaneous pressure loss.A further consequence of the tilting is the bending of the knife drive pin built into the screw shaft, which is firmly connected to a screw, thus pressing the knives against the perforated discs on one side. This causes the knives to tilt into the vertically positioned disc to increase energy consumption in the device by up to 40%.

[0021] The displacement of the non-blocking screw conveyors in the intake area from their running center also leads to a displacement of the blocking screw conveyors and the non-blocking pre-shredding screws, with a corresponding wear effect, since all screws are arranged along two axes in the device. Furthermore, such displacement from the running center away from the longitudinal axis leads to tilting and bending of a rotating knife arranged on one of the axes in the cutting unit, which causes increased wear on the rotating knife and the associated perforated disk. In extreme cases, this can lead to the destruction of the rotating knife. As a result of the increased wear, the service life of conventional shredding devices is shortened, the quality of the shredded material deteriorates, and the effort and cost of repairs increase.In particular, if there is a large distance between the bearing points of the screws in the receiving area on the one hand and in the cutting area of ​​the device on the other hand, the tilting and bending as well as the wear in the cutting unit increase.

[0022] There is therefore a need for an improved solution for a device and method for conveying and comminuting processed materials.

[0023] The invention is based on the object of overcoming the disadvantages of the prior art and, in particular, of providing a device and method for conveying and comminuting processed materials, whereby targeted, gentle, and high-quality comminution of a processed material, in particular of animal or plant origin, is possible, even in a frozen state, and whereby the reliability of the device is increased and its service life and effectiveness are improved. Furthermore, the energy consumption of the device is to be reduced.

[0024] The problem is solved by a device for conveying and comminuting processed materials with the features according to claim 1 of the independent patent claims. Further developments are specified in the dependent patent claims.

[0025] It is provided that the device has a housing which comprises a receiving area with a receiving opening, a transition area, a transport area, a pre-shredding area, a cutting area and an output area with an output opening.

[0026] It is further provided that a material to be minced, such as meat, is fed into the device via the receiving opening of the partially open receiving area.

[0027] The material to be shredded reaches the receiving area and is picked up by non-blocking screw conveyors arranged in pairs and rotating at a speed ni in the receiving area, or is drawn into the winding flights of the non-blocking screw conveyors and transported in a conveying direction within the device. The material to be shredded is conveyed by the non-blocking screw conveyors from the receiving area to a transition area. Within this transition area, which represents a transition in the housing between the partially open receiving area and the closed transport area, the non-blocking screw conveyors can have a design of their winding flights or their likewise winding boundaries that deviates from the design of the winding flights or winding boundaries of the non-blocking screw conveyors in the partially open receiving area.

[0028] This different design of the winding flights or the winding boundaries of the non-blocking screw conveyors results from the different tasks in these areas. While the non-blocking screw conveyors must pick up or draw in the material to be shredded in the intake area, in the transition area the material to be shredded, which has already been picked up in the spaces between the flights of the non-blocking screw conveyors, is conveyed or further conveyed in the conveying direction. Therefore, the outer diameter of the non-blocking screw conveyors, determined by the flights or boundaries, can decrease in the transition area. Alternatively or additionally, the type or design of the flights or boundaries can change in the transition area.A further function of the aisles and limits of the non-blocking screw conveyors is to partially crush the material being processed when it is picked up or drawn into the receiving area.

[0029] From the transition zone, the material to be processed continues in the conveying direction to the transport zone. In this transport zone, the material to be processed is picked up by locking screw conveyors rotating in pairs at a speed of n2 and then conveyed or transported further in the conveying direction.

[0030] Both the non-blocking screw conveyors and the blocking screw conveyors are designed as double screws consisting of two separate, counter-rotating screws.

[0031] In general, a screw conveyor within the meaning of the present invention is a shaft rotating within a housing, around which spirally wound flights are wound. These flights are formed between spirally wound boundaries, for example, made of metal or plastic. The boundaries and the shaft can either be made in one piece, or the boundaries can be arranged around the shaft and fixed to it.

[0032] For the purposes of the invention, a blocking screw conveyor is understood to be a screw conveyor designed such that conveying, i.e. transport of the processing material in a conveying direction, occurs through displacement of the intermeshing, sealing and rotating screw flights, whereby backflow of the processing material against the conveying direction, particularly in the edge regions of the screw conveyor beyond the boundaries, is almost completely avoided. A blocking screw conveyor for the purposes of the invention also includes screw conveyors with a backflow rate against the conveying direction of up to 2% of the processing material. Such blocking screw conveyors are described below with the property of no backflow or almost no backflow. A blocking screw conveyor transports the processing material in the conveying direction within the winding flights, whereby the processing material is not crushed.Such locking screw conveyors have a geometric body that seals on all sides and is designed with sealing interlocking elements.

[0033] By means of a blocking conveyor screw, the material to be transported, in this case mostly foodstuffs, in particular foodstuffs of animal or plant origin, is displaced and thus transported within the winding channels by the displacing effect in smooth, identically shaped housings of the intermeshing screw channels, which are sealingly adapted to the conveyor screws with very small running tolerances, without exerting any pressure on the foodstuffs.

[0034] With a locking screw conveyor, the material being processed is not transported further because pressure is exerted on the material between the locking screw conveyor and the housing surrounding the locking screw conveyor, but rather all outer surfaces of the boundaries of the locking screw conveyor, including the housing, are sealed. Such a locking screw conveyor is designed to slide within a housing that corresponds to the external shape of the locking screw conveyor. There is no gap between the housing and the outer surfaces of the helically wound boundaries of the locking screw conveyor. As a rule, the helically wound flights between the boundaries of a locking screw conveyor are of the same width with flat sealing functions across the entire screw geometry, in contrast to non-locking screws conveyors.With a locking screw conveyor, a sealing effect is created by all surfaces of the screw geometry and by the outer surfaces of the boundaries sliding along the housing. The ratio of the width of the boundaries to the width of the spiral flights is 1:1. To adapt to the material's granularity, the dimensions for the width of the boundaries and the width of the spiral flights can be selected to be different, while the ratio of the dimensions of the width of the boundaries to the width of the spiral flights remains constant (1:1). For example, when comparing very small and very large granularity, the dimensions can be a factor of 5 larger.

[0035] The blocking screw conveyors in this invention are designed as twin screws. The spiral flights of a first screw conveyor and the spiral boundaries of the second screw conveyor engage in a sealing manner, creating a shaft seal including the wall shapes for the respective conveying chamber. Due to the sealing effect between the spiral flights and the spiral boundaries in an overlapping area of ​​the blocking screw conveyors, the material to be processed can be transported very gently and continuously without the application of pressure in the non-overlapping areas of the blocking screw conveyors. The ratio of the width of the spiral boundaries to the width of the spiral flights is designed to be 1:1 for paired, blocking screw conveyors.

[0036] A non-blocking screw conveyor is used to transport the material to be processed, i.e., the raw material. The material to be transported is subjected to pressure, which is built up between the housing surrounding the non-blocking screw conveyor and the screw conveyor, or the outer surfaces of the screw conveyor's boundaries, with the material being processed. The material to be processed or shredded acts analogously to a mechanical component in the form of a coupling, which provides the power transmission for generating the shredding energy through holding and shear forces with the rotation of the non-blocking screw conveyor, resulting in a linear forward movement in a receiving area or a pre-shredding area of ​​the device for conveying and shredding processed materials.The thrust, the processing energy in the cutting area, is generated by the mass of material being processed fed from the screw conveyor, combined with the resistance of the cutting unit used for comminution. The structural support force of the raw material generates the thrust force for comminution of this conveyed raw material for comminution in the cutting unit. This dual function of the raw material—that the material being processed assumes its own processing function through the power transmission as its primary function—is a special feature of such a device for conveying and comminuting processed materials. The achievable pressure level is limited by the strength properties of the material being processed during the power transmission.

[0037] In state-of-the-art single-screw extruders and meat grinders, the geometry of the screw's helix or shaft is generally designed so that the cross-section narrows toward the exit, i.e., the discharge. This generates high pressures to force plastic or viscous material through mold templates or into casting molds. Non-blocking screw conveyors can exert high forces on the material being processed and, depending on their properties, generate considerable pressure. In such wall-supported conveyor systems, the mechanical force transmission generally leads to significant heating and partial destruction of the material being processed. Heating temperatures of 10 K to 16 K are possible, resulting from significant backflow in the edge area of ​​the screw conveyor via the outer surfaces of the spiral flights and the support geometry of the housing.A return flow channel is formed between the housing and the conveyor screw, counter to the actual conveying direction, whereby the processed material evades the thrust of the conveyor screw, which acts against a cutting unit. The resulting friction generates heat and thus causes the processed material to become softer, sometimes even pasty. The increasing flowability of the processed material is a basic prerequisite for penetration into the openings of the perforated discs in the cutting unit. Frozen foods therefore require the heating induced by the non-blocking conveyor screws within the pressure chamber in order to be shredded and processed by a cutting unit. According to the invention, at least one non-blocking pre-shredding screw is arranged in a pre-shredding area following the transport area, viewed in the conveying direction.Alternatively, pre-shredding screws arranged in pairs can be arranged in this pre-shredding area. It is further provided that one non-blocking pre-shredding screw or the paired, non-blocking pre-shredding screws rotate at a speed na.

[0038] The essence of this invention is thus that the speed ni of the non-blocking screw conveyors in the receiving area can be adjusted independently of the speed n2 of the blocking screw conveyors in the transport area and independently of the speed n3 of at least one non-blocking pre-shredding screw arranged in the pre-shredding area. This ensures a suitable and sufficient intake of the processed material, for example foodstuffs, in the receiving area. This makes it possible to convey a desired quantity of the processed material in the transport direction. In particular, it is advantageous to set a higher speed ni of the non-blocking screw conveyors in the receiving area compared to the speed n2 of the blocking screw conveyors in the transport area in order to maintain pressure through the mass feed.In general, the quantity of the material being transported or conveyed in the conveying direction can be controlled by regulating the speed ni.

[0039] Furthermore, by adjusting the speed n3 of the at least one pre-shredding screw arranged in the pre-shredding area independently of the speeds ni and n2, a working pressure can be built up within the pre-shredding area, which is also referred to as a pressure chamber. This working pressure acts, for example, in particular on a perforated disc having several openings, which is arranged in a cutting area downstream of the pre-shredding area within a cutting unit. This working pressure generated or built up there is then used for further processing of the material to be processed or for its comminution in the cutting unit comprising the at least one perforated disc and at least one rotating knife. The rotating knife of the cutting unit can rotate, for example, at the speed n3.In the following, this description provides examples of non-blocking pre-shredding screws arranged in pairs in the pre-shredding area, without restricting the invention to this design.

[0040] The possibility of setting the speeds n2 and n3 independently of each other makes it possible to discharge the material to be processed through the transport area as a non-return mass and to place the material to be processed only in the pre-shredding area under the working pressure required for the shredding of the material by the cutting unit as a material structural property in effect of the resistance of the shredding system and the shredding task to be solved.

[0041] The blocking conveyor screws in the transport area ensure a continuous supply of the material to be processed from the receiving area via the transition area and the transport area into the pre-shredding area, whereby the material to be processed is available in the pre-shredding area in sufficient quantity or in excess, so that a working pressure necessary for shredding the material to be processed by the cutting unit is achieved.

[0042] It is intended that a pressure sensor be arranged in the pre-shredding area, which measures the pressure or the resulting working pressure due to the excess mass of the pre-shredded material in the pre-shredding area. This makes it possible to measure the current working pressure prevailing in the pre-shredding area immediately upstream of the cutting unit arranged in the cutting area and compare it with a specified pressure value. Such specified pressure values ​​have been determined experimentally, for example, and correspond to an optimally shredded and quality-appropriate material, which is discharged via the discharge opening of the discharge area after shredding in the cutting area.

[0043] It is further provided that a temperature sensor is arranged in the pre-shredding area, which measures the temperature of the pre-shredded material to be processed in the pre-shredding area. The measured values ​​of the working pressure and / or the temperature of the material to be processed in the pre-shredding area are used to adjust the speeds ni and n2 of the paired non-blocking screw conveyors in the receiving area and the paired blocking screw conveyors in the transport area accordingly, in order to thus regulate the working pressure and / or the temperature of the material to be processed in the pre-shredding area.

[0044] According to the invention, the evaluated data of the pressure sensor and / or the temperature sensor arranged within the pre-shredding area are used to adjust the corresponding rotational speeds n^, n2, and n3. During this evaluation of the sensor data, a quantity of the material to be processed fed through the receiving opening and a quantity of the shredded material to be processed discharged from the discharge opening can also be incorporated and used to adjust the corresponding rotational speeds ni and n2.

[0045] Known parameters include, for example, information about which hole sizes in a perforated disc, with which raw material type, and at which temperature, can achieve which shredding performance per minute. Furthermore, the number of openings or holes per perforated disc is known. From these parameters, the feed rate of the processed material, as well as the required speed of the screws and the rotating blade of the cutting unit, can be calculated.

[0046] Example:

[0047] Conveying capacity of the screws: m= 1.2 kg / revolution Raw material= R II

[0048] The R II designation of the raw material describes a quality criterion for the composition of muscle meat, fat, and collagenous tissue according to the state of the art. This corresponds, for example, to the meat cut of an animal carcass with a 75% water content, which describes the proportion of liquid without any solids. The total mass of the meat is divided into 5% fat, 20% meat protein, and 5% connective tissue protein.

[0049] Hole / opening in the perforated disc: d = 3 mm Number of holes in the perforated disc: n = 1030 1. Calculation example:

[0050] Fresh meat with a temperature range of t= -3 °C to +5 °C

[0051] Drilling performance: m = 80 g / min

[0052] Number of holes on the perforated disc: n = 1030

[0053] Feed rate: m1 = number of holes on the perforated disc * drilling rate m1 = 1030 * 80 g / min = 82400 g / min

[0054] The screw speed n in revolutions / min is calculated from the quotient of the conveying capacity m1 in kg / min and the conveying capacity of the screws m in kg / revolution. m = 82.4 kg / min ÷ 1.2 kg / revolution = 68.6 revolutions / min

[0055] Thus, the required screw speed n = 68 revolutions per minute for a disc output.

[0056] 2. Calculation example: frozen meat with a temperature t = -18°C

[0057] Drilling performance: m = 10 g / min

[0058] Number of holes on the perforated disc: n = 1030

[0059] Feed rate: m1= number of holes on the hole disc * hole rate m1 = 1030 * 10 g / min = 10300 g / min

[0060] The screw speed n in revolutions / min is calculated from the quotient of the conveying capacity m1 in kg / min and the conveying capacity of the screws m in kg / revolution. m = 10.3 kg / min ÷ 1.2 kg / revolution = 8.5 revolutions / min

[0061] Thus, the required screw speed n = 8.5 revolutions per minute for a disc output.

[0062] This advantageously allows adjustment of the working pressure of the material to be processed in the pre-shredding area depending on a specified temperature and a specified pressure. The working pressure of the material to be processed in the pre-shredding area or the pressure chamber is regulated according to the invention, since excessively high working pressure leads to compression and, particularly in the case of frozen material, to undesirable compaction. Such undesirable compaction of the material to be processed prevents the material from forming cones, i.e., the material from penetrating the openings of the perforated disc, thus preventing the material from being shredded in the cutting unit of the device for conveying and shredding material to be processed.

[0063] By means of an existing pressure sensor, the strength of the material being processed can be monitored, which allows the energetic state of the material to be controlled, particularly when processing pieces of meat, and thus enables the material to be relaxed under optimal conditions, which advantageously improves the formation of cones in the openings of the perforated disc.

[0064] Particularly preferably, the measured values ​​of the pressure sensor and / or the temperature sensor are used to regulate the speed ni of the paired, non-blocking conveyor screws in the intake area and thus to control the quantity of material to be processed into the pre-shredding area.

[0065] It is also intended to reduce undesirable compaction caused by material elements pressing against one another by arranging tool elements on the paired, non-blocking pre-shredding screws within the pre-shredding area. These tool elements ensure that the material being processed is loosened in the pre-shredding area. Open, non-blocking screw geometries are used. These react to excessive pressure from raw material at the blockage point, the tool system, with raw material backflow. This overflows the conveyor channels of the screw pair and exchanges with the feed and return flow movement, similar to a mixing process with a temperature increase. This movement sequence only ends when meat plugs form again in the openings of the perforated disc and are conveyed away. This status can be recorded by measuring data using pressure sensors and / or temperature sensors.The invention provides that the paired, non-blocking screw conveyors, the paired, blocking screw conveyors, and the paired, non-blocking pre-shredding screws are arranged on two parallel axes. A first non-blocking screw conveyor, a first blocking screw conveyor, and a first non-blocking pre-shredding screw are arranged on a first axis, while a second non-blocking screw conveyor, a second blocking screw conveyor, and a second non-blocking pre-shredding screw are arranged on a second axis.

[0066] It is further provided that, with such an arrangement of the screws on two axes, the paired, non-blocking conveyor screws are connected to a first controllable drive unit, the paired, blocking conveyor screws are connected to a second controllable drive unit, and the paired, non-blocking pre-shredding screws are connected to a third controllable drive unit. Due to this separate assignment to different drive units, all paired screws can be operated optionally at the same speed, at partially the same speed, or at different speeds ni, n2, and n3, since the drive units are designed to be controllable in terms of their speed.

[0067] For the practical implementation of this drive concept, the second drive shafts of the blocking screw conveyors, driven by the second controllable drive unit, are arranged or run within the first drive shafts of the non-blocking screw conveyors, driven by the first controllable drive unit, and thus inside the non-blocking screw conveyors. Furthermore, the third drive shafts of the non-blocking pre-shredding screws, driven by the third controllable drive unit, are arranged within the second drive shafts of the blocking screw conveyors and thus run through both the non-blocking screw conveyors and the blocking screw conveyors of the device.Since the drive shafts on both the first axis and the second axis are arranged one inside the other, the various screws arranged in pairs can be operated at different speeds ni , n2 and na.

[0068] In an alternative embodiment, it is provided that the non-blocking conveyor screws are arranged connected to a first drive unit and that the blocking conveyor screws and the non-blocking pre-shredding screws are arranged connected to a second drive unit.

[0069] A single drive shaft coupling of the locking screw conveyors with the non-locking screw conveyors is provided for cases where the receiving process of the processed material or raw material is temperature-controlled or where technologically justified parameters are introduced into the initial state of the processed material. This is the case when the production of the end products requires these parameters for maturation or other product-internal processes to achieve the quality characteristics of the product or the shredded processed material.

[0070] Examples of finished products include: high-quality raw sausage products with low temperatures t = up to -10 °C, fresh meat products in the temperature range t = -3 to + 5 °C, cooked sausages in the temperature range up to t = + 80 °C,

[0071] Disc openings d = 3, 4, 5, 6 and 8 mm are provided for a targeted temperature adjustment in the material being conveyed in the case of significantly reduced raw material temperatures in order to generate the parameters for the crushing processes to be achieved.

[0072] By separately adjusting the speed ni of the non-blocking conveyor screws in the intake area, the product being processed, especially the meat, can be loosened in a controlled manner. This also allows the quality of the product to be ground to be taken into account.

[0073] The idea is that, with a high throughput of material to be shredded, a high working pressure in the region of 30 bar can be generated in the pre-shredding area by the paired, blocking screw conveyors in conjunction with the paired, non-blocking pre-shredding screws. This is achieved in particular due to the minimal backflow of the material to be processed during transport with the blocking screw conveyors. By variably adjusting the speed of the non-blocking screw conveyors in the intake area, both an increase and an adjusted decrease in the working pressure in the pre-shredding area, which is also referred to as the pressure chamber, can be achieved by transporting a sufficiently large or decreasing amount of the material to be shredded via the intake area in the conveying direction to the pre-shredding area. This leads to numerous advantages, particularly in the processing of meat.Due to the adjustable high working pressure, the strength bonds of the various meat types within the meat can be positively influenced in the pre-mincing area. Openings in a perforated disc of a cutting unit located in the cutting area can thus have diameters in the range of 3 to 4 mm or even 1 to 2 mm.

[0074] Alternatively, several such perforated discs, each with an associated rotating knife, can be arranged one after the other in a cutting unit, for example with successively decreasing diameters of the openings of the perforated discs for a gradual degree of comminution of the material to be processed.

[0075] By means of the level of a predetermined working pressure in the pre-shredding area, the existing collagen can also be advantageously shredded, since even with collagen, at least partial cone formation occurs due to its high strength with necessary forming pressures for meat cones of approximately p = 20 bar in the openings of the perforated disc.

[0076] This efficient transport also advantageously leads to lower energy consumption. The paired, locking screw conveyors require only 0.6 Wh per kg of material to be processed, whereas conventional, non-locking screw conveyors require 6 Wh per kg of material to be processed for comparable material transport tasks.

[0077] Since any additional energy input, such as through crushing and shearing stresses due to the transport of the processing material by means of a non-blocking conveyor screw, reduces the quality of the processing material, in particular the meat, the device according to the invention not only saves energy but also increases the quality of the processing material to be minced or processed, such as meat. The stress on the meat during transport by the device for conveying and mincing processing materials in the conveying direction to the cutting unit in the cutting area is advantageously minimized and the destruction of the meat structure up to the point of mincing in the cutting area is prevented. This preserves the strength of the meat structure, especially for high-quality products. There is no denaturation due to mechanical forces or generated heat during transport.Thus, the connection between collagen and muscle is not destroyed during the transport of the processed material in the device.

[0078] It is planned that pairs of non-blocking pre-shredding screws rotating at a speed of n3 are arranged in the pre-shredding area or in the pressure chamber. This allows not only additional pre-shredding of the material and a release of solids within the pre-shredding area, but also the processing of both frozen and fresh material, for example, at temperatures a few degrees above freezing.

[0079] The combination of different screws for transporting or conveying the processed material in the device with independent adjustment of the corresponding speeds n2, n3 and n4 makes it possible to meet the different requirements of the various processed materials or foodstuffs. The compaction of frozen foodstuffs, particularly frozen meat products, which occurs upstream of the cutting unit in the pre-shredding area can be specifically counteracted by targeted control of the speeds n1, n2 and n3 of the different screws. This allows the material penetration conditions into the intended sizes of the openings in the perforated disc of the cutting unit to be selected as desired, independently of any thrust generation and without force transmission between the screw and the housing containing the raw material, defined by the mass thrust of the sealing locking screws.The locking screws used in the device according to the invention generate a significantly higher thrust force or pressure in the cutting area in front of the perforated disk. Compared to a prior art mincer, the invention makes it possible to generate up to ten times higher thrust force.

[0080] The device according to the invention for conveying and comminuting processed materials makes it possible, in particular, to influence the various states of the processed material or raw materials, i.e., foodstuffs, especially meat products, by providing the appropriate predetermined and controlled working pressure in the pre-comminution area. Depending on the application, the parameters can be adjusted to the required or desired states, in particular solid, lumpy, soft, hard, pasty, liquid, warm, and cold.

[0081] Crucial for optimal processing here is that the material strength of the material being processed is not disturbed within the paired, locking screw conveyors. The material being processed is not altered during transport through the transport area to the pre-shredding area, and processing only takes place within the pre-shredding area. Processing thus takes place specifically within the pre-shredding area or the pressure chamber, as well as in the cutting unit located in the cutting area.

[0082] As already mentioned, the cutting unit comprises at least one perforated disc with multiple openings and at least one rotating blade. Alternatively, several such perforated discs, each with an associated rotating blade, can be arranged one after the other in a cutting unit, for example, with successively decreasing diameters of the perforated disc openings to gradually achieve the desired degree of comminution of the material to be processed.

[0083] In both designs, at least one rotating blade, located within the cutting unit, is provided with a cutting and conveying function to relieve the tension on the material being processed. The cutting unit can also be referred to as a cutting set.

[0084] The relaxation of the material being processed is particularly relevant when mincing meat. The mincing of meat using a perforated disc and an adjacent rotating knife does not, as is often assumed, occur continuously in a flowing process. Rather, it has been shown that a discontinuous, abrupt particle formation occurs due to a prior pressure increase in the cutting area, creating a compression time as a pressure increase leading to the formation of meat plugs in the holes in the cut, in order to be separated with a knife cut. The penetration of the meat into the openings of the perforated disc, forming meat plugs, is a mechanically extremely stressful process that is accompanied by the tearing of parts of the internal structure of the meat.The demonstrated abrupt formation of the meat cones is evidence that the cutting of meat is a process in which the external force causes material deformation, even to the point of fiber tearing. Thus, the relaxation of the large pieces of meat from which the meat cones are separated is a prerequisite for a good, gentle, and efficient cutting process in the cutting unit.

[0085] It is further provided that the housing in the transport area has a conveyor housing which seals around the blocking conveyor screws and forms a sliding bearing and is smoothed on the inside, wherein outer surfaces of wound boundaries of the blocking conveyor screws are arranged in a sliding manner on the conveyor housing in order to prevent, with their lengths and surface areas, the screw shaft deformations which arise during the raw material intake in the hopper area via the common bearing function of the entire conveyor housing area with the blocking conveyor screws by absorbing forces.

[0086] By arranging the blocking screw conveyors in a conveyor housing in the transport area, a dynamic bearing system is formed along the length of the housing. The outer surfaces of the spiral boundaries of the blocking screw conveyors are designed to correspond to the conveyor housing surrounding the outer surfaces of the smooth boundaries of the blocking screw conveyors. This means that the outer surfaces of the spiral boundaries form a plain bearing with the conveyor housing, with smooth housing surfaces made of steel or other bearing-paired material combinations. This is achieved by providing at least the spiral boundaries of the blocking screw conveyors and the conveyor housing from a material pairing exhibiting sliding properties.For this purpose, the material pairings between the two parts are selected in such a way that a plain bearing pairing is created that virtually eliminates wear, whereby the dynamic bearing function is coordinated with the length of the locking conveyor screws and with the number of winding flights within the conveyor housing.

[0087] One such material used for the spiral boundaries of the locking screw conveyors and for the conveyor housing is plastic. Examples of materials include POM (polyoxymethylene), PTFE (polytetrafluoroethylene), or PE (polyethylene). Alternatively, metallic materials with sliding surface properties can also be used to form a plain bearing pair.

[0088] By arranging the blocking screw conveyors in this way in a conveyor housing in the transport area and by forming a dynamic bearing system or plain bearing, displacement of the blocking screw conveyors away from the longitudinal axis is counteracted and deformation of the screws due to the forces acting during raw material intake is significantly reduced, since the additional plain bearing with its longitudinal extension in the housing significantly shortens the distance between the bearing points of the screws in the receiving area on the one hand, in the cutting area on the other hand and additionally in the transport area of ​​the device.

[0089] By reducing the displacement away from the longitudinal axis, the tilting and bending of the rotating knife spindle, arranged on one of the axes, with the knife in the secured discs of the cutting unit is virtually eliminated. Furthermore, tilting, which causes significant friction and wear, is eliminated. As a result, the service life of the devices according to the invention is extended, the quality of the shredded material is increased, and the effort and costs for repairs are reduced. In addition, a reduction in energy consumption of up to 40% is achieved.

[0090] With this form of assuming a bearing function by the designed plain bearing as a third bearing, the lever lengths with deforming forces of the screws during raw material intake are shortened by a factor of 3 to 5, the intake forces are distributed centrally on the paired, non-blocking conveyor screws and the force effect on the individual, non-blocking conveyor screws is halved.

[0091] It is also planned that, in a section of a transition zone between the receiving area and the transport area, the non-blocking conveyor screws are designed as non-blocking granulating screws for pre-shredding the processed material. These non-blocking granulating screws advantageously take over the chopping into smaller pieces of the processed material before the processed material reaches the transport area. The non-blocking granulating screws can be designed as part of the paired, non-blocking conveyor screws. In this case, for example, the structure of the spiral boundaries changes such that hook-shaped knife elements are incorporated into the screw flights. These knife elements penetrate the meat as they rotate, creating cuts and tears in the raw material with shredding effects.The paired arrangement of the screw flights with the knife elements of the screws rotating away from the center doubles the tearing and cutting effect, ultimately resulting in the desired meat fragmentation. In this design, the speed n of the non-blocking granulating screws corresponds to the speed of the non-blocking conveyor screws. Thus, in this case, the speed n of the non-blocking granulating screws is also adjusted depending on the operating pressure within the pre-shredding range.

[0092] In an alternative embodiment of the device, the paired, non-blocking conveyor screws, which extend across the receiving area, are mechanically decoupled from the paired, non-blocking granulating screws, which extend across the transition area. In this case, the rotational speed n of the non-blocking granulating screws can be adjusted independently of the rotational speed m of the non-blocking conveyor screws if appropriately adjustable drive units are provided. It is also generally provided that a separate, adjustable drive unit can determine both the rotational speed of the associated screws and the direction of rotation of the associated screws for specific purposes.

[0093] Furthermore, the non-blocking granulating screws are provided with interchangeable tools whose task is to shape the size of the processed material in such a way that uniform, uninterrupted intake of the processed material by the downstream, blocking conveyor screws is ensured. Such interchangeable tools offer the possibility of adapting the device for conveying and comminuting processed materials to different processed materials or foodstuffs.

[0094] It is intended that the transport area and the pre-shredding area have a constant cross-section and / or are arranged within a common housing. The cross-section of the area in which the material to be processed is transported along the transport path in the conveying direction thus does not change in the transport area and the pre-shredding area.

[0095] Alternatively, the cross-section of the housing of the device and the outer diameter of the screws taper in the conveying direction, i.e. in the direction of the pre-shredding area.

[0096] It is further provided that external heat energy is supplied to the transport area of ​​the device. For example, elements are arranged between the device housing and the conveyor housing, which allow heat energy to be transferred into the interior of the transport area by means of water, oil, induction, microwaves, or ultrasonic excitation. The introduction of heat makes it possible to convert the material to be processed into a deformable material state, which facilitates pre-shredding following transport through the transport area and comminution of the material to be processed in the cutting area, particularly when using chilled or frozen material.

[0097] The problem is also solved by a method for comminuting a material to be processed having the features according to claim 8 of the independent patent claims. Further developments are specified in the dependent patent claims.

[0098] The method according to the invention comprises the following steps: a) feeding a material to be shredded into a receiving area via a receiving opening, b) drawing the material to be shredded into non-blocking conveyor screws rotating in pairs at a speed ni in the receiving area and transporting the material to be shredded in a conveying direction, c) transferring the material to be shredded in the conveying direction to a transport area, d) transporting the material to be shredded through the transport area by means of blocking conveyor screws rotating in pairs at a speed n2 in the conveying direction into a pre-shredding area without backflow of the material to be shredded within the transport area, e) generating a working pressure acting on the material to be shredded in the conveying direction in a pre-shredding area upstream of a cutting area by means of at least one screw rotating at a speed n3,non-blocking pre-shredding screw with simultaneous pre-shredding of the processing material in the pre-shredding area, f) shredding of the processing material by means of at least one perforated disc having openings arranged in a cutting area and by means of at least one rotating knife arranged in the cutting area and belonging to the perforated disc, g) removal of the shredded processing material via an output opening of an output area, h) measuring a current working pressure acting on the processing material to be shredded in the pre-shredding area, i) comparison of the measured current working pressure with a pressure setpoint value and determination of a deviation between the current working pressure and the pressure setpoint value and j) upon determination of an amount of the deviation between the current working pressure and the pressure setpoint value above a predetermined tolerance threshold, at least one of the speeds , n2,n3 to achieve the pressure setpoint in the pre-shredding area.,

[0099] By changing at least one of the speeds ni, n2, na to achieve the specified pressure value in the pre-shredding area, various product groups can be advantageously produced, three of which are listed below as examples.

[0100] • Product group I: Production of minced processed material with very small disc openings (d = 0.6 to 1.5 mm) for fresh meat in a finely minced state as a finished sausage mass that can be filled into casings.

[0101] • Product group II: Production of crushed processing material with raw materials in a deep-frozen state (t = -10 °C to -18 °C) and disc openings of the last perforated disc arranged towards the output area with openings which have diameters in the range of 3 mm to 16 mm.

[0102] • Product group III: Conveying process after passing through the tool system for the purpose of filling into molds and containers.

[0103] It is also planned that the material to be shredded is pre-shredded in a transition area, i.e., a space between the receiving area and the transport area. In this area, either separate, paired, non-blocking granulating screws are arranged, or some of the paired, non-blocking conveyor screws in the receiving area are designed as non-blocking granulating screws. This allows the material to be pre-shredded and transferred to the transport area as smaller pieces. This enables optimal shredding and processing of both frozen and chilled foods.

[0104] According to the concept of the invention, a device for conveying and comminuting processed goods, in particular for comminuting meat products, is provided, in which a combination of several paired screws with different properties and individually adjustable speeds ni, n2 and ns is combined. A pair of separately controllable, non-blocking conveyor screws in the receiving area of ​​the device results in a defined input of processed goods into the transport area and the pre-comminution area, which functions as a pressure chamber. In particular, different speeds ni and n2 of the paired, non-blocking conveyor screws and the paired, blocking conveyor screws can be used to create optimal conditions for transporting the processed goods in the conveying direction.Furthermore, this allows a predetermined working pressure to be achieved in the pre-shredding area, at which the shredding of the material to be processed in the cutting area takes place in such a way that the shredded material is of optimal quality. Furthermore, the energy required to operate such a device for conveying and shredding materials can be reduced by up to 70%.

[0105] It is particularly advantageous to feed the material to be processed into the receiving area of ​​the device at a speed ni of the paired, non-blocking conveyor screws which is greater than the speeds n2 and n3 of the paired, blocking conveyor screws and the paired, non-blocking pre-shredding screws.

[0106] The blocking conveyor screws arranged in pairs in the transport area, which are used according to the invention and have no or almost no backflow of the processing material, enable a defined input of processing material into the pre-shredding area of ​​the device upstream of the cutting area. Furthermore, such a controllable input of processing material into the pre-shredding area can be used to predetermine the working pressure in the pre-shredding area, which the processing material is subjected to immediately upstream of the cutting area, in order to process it according to slice size and material condition. Thus, the working pressure in the pre-shredding area will increase in the event that the input of processing material, i.e., the quantity of processing material, into the pre-shredding area needs to be increased due to a decrease in the processing volume.On the other hand, the working pressure in the pre-shredding area will decrease if the input of processing material into the pre-shredding area is reduced. Thus, for example, by changing the speed n2 of the paired, locking screw conveyors in the transport area, the working pressure in the pre-shredding area can be influenced until a set pressure value for the working pressure is reached. The current working pressure in the pre-shredding area is measured using a pressure sensor, compared with the set pressure value, and any deviation between the current working pressure and the set pressure value is determined. A change in the speed n2 of the paired, locking screw conveyors in the transport area only occurs if the deviation between the current working pressure and the set pressure value exceeds a specified tolerance threshold.Otherwise, the speed n2 is maintained. Thus, if a deviation between the current working pressure and the set pressure value is detected that exceeds a specified tolerance threshold, the speed n2 is reduced to achieve the set pressure value. Alternatively, the speed n3 can also be adjusted to achieve the set pressure value.

[0107] Thus, the working pressure in the pre-shredding area before the cutting area can be regulated so well by the defined input of processing material that when processing meat, the material state of the meat and thus the meat cone formation can be influenced in a controlled manner and defined for quality-oriented processing.

[0108] In an alternative embodiment, the dosage of the material to be processed into the pre-shredding area is controlled by adjusting or changing the speed ni of the paired, non-blocking screw conveyors. In this case, the working pressure in the pre-shredding area will increase if the speed m of the paired, non-blocking screw conveyors increases up to the maximum fill level of the blocking screw conveyors, as the input of material to be processed, i.e. the quantity of material to be processed that is conveyed into the pre-shredding area, increases. On the other hand, the working pressure in the pre-shredding area will decrease if the speed n1 of the paired, non-blocking screw conveyors decreases, whereby the fill level of the blocking screw conveyors decreases.

[0109] Processing a chilled or frozen product in the device according to the invention also has the advantage that the product is not heated significantly during the comminution process, ensuring its qualitative state remains unchanged. Rather, the stored cold allows for sufficient cooling of the product, which offers significant advantages for hygienic reasons, particularly when processing meat products. The reason for the low heating of the product in the device according to the invention is also that the product does not have to make its own contribution to the raw material supply, being transported very gently and continuously in the non-overlapping areas of the blocking screw conveyors without significant pressure.

[0110] In the event that the material to be shredded must have a higher temperature for better processing, for example in the cutting unit, a supply of external heat energy is provided in the transport area or preferably in the pre-shredding area of ​​the device, wherein this heat energy is transferred into the interior of the transport area or preferably the pre-shredding area and thus into the material to be processed using media such as water, oil, induction, microwaves or ultrasonic excitation.

[0111] Through this introduction of heat, it is possible to convert the material to be processed into a deformable material state, in which pre-shredding and shredding of the material to be processed in the cutting unit arranged in the cutting area is facilitated.

[0112] It is important that the material to be processed in the pre-shredding area before the cutting area is in a machinable grain strength state. This strength state occurs when the wear resistance of the cutting unit's tools in the cutting area and the resistance of the material strength of the material to be processed are evenly achieved through a reduced material strength state due to the penetration behavior of the material into the openings or bores of the perforated disc.

[0113] For this purpose, pairs of non-blocking pre-shredding screws are arranged in the pre-shredding area. Alternatively, only one non-blocking pre-shredding screw is arranged in the pre-shredding area. Firmly bonded, natural, highly elastic material bonds in the material to be processed can be broken up by processing using these paired pre-shredding screws or the single pre-shredding screw in the pre-shredding area. In the following, this description will only address the variant of paired, non-blocking pre-shredding screws, without limiting the present invention to this embodiment.

[0114] The resulting heating of the material to be processed is made possible by the mixing properties of the non-blocking screw conveyors, with their low efficiency, which promotes deformation of the material and thus suitable processing in the appropriate material state. Excessive rigidity of the material to be processed would prevent processing using the perforated discs in the cutting unit, as the material must be sufficiently fluid to be pressed into the openings of the perforated disc and shredded by the associated rotating blade.For this reason, the combination of gentle transport by the blocking conveyor screws in the transport area and the targeted pre-shredding and the generation of a working pressure for the material to be processed in the pre-shredding area by means of the non-blocking pre-shredding screws, which can pre-shred, loosen, slightly mix and heat the material to be processed and put it under the required working pressure, is particularly advantageous.

[0115] The paired, non-blocking pre-shredding screws in the pre-shredding section are responsible for breaking up compacted, i.e., solidified, material to be processed due to the working pressure occurring in the pre-shredding section. Due to their lower pressure retention capacity, these pre-shredding screws act with the main conveying mass from the transport section against the back pressure of the cutting unit in the cutting section, which has a limited throughput, driven by the higher degree of shredding to be achieved.

[0116] At least one rotating knife arranged in the cutting area separates the processed material, such as a piece of meat, the so-called meat cones, that has penetrated into the openings of the associated perforated disc from the more compact, large-piece mass of the processed material and transports the thus shredded processed material further in the conveying direction to the output area.

[0117] This comminution eliminates the internal solidification of the material being processed, such as a large piece of meat, and relaxes the tension. Subsequently, meat cones can form again in the holes or openings of the perforated disc under the shear pressure caused by the working pressure in the pre-comminution area by the non-blocking pre-comminution screws. According to the process, this repetitive process during comminution of the material is controlled and monitored by measuring the current pressure or working pressure in the pre-comminution area using a pressure sensor to control the feed of the material being processed.

[0118] Relaxation of the processed material is necessary for food of animal origin because meat in particular is a tissue made up of material components with differently strong, spatially connected types of substances with biologically firmly intertwined individual functions from a single animal. Nothing flows easily from such tissue. The formation of meat cones is only partially possible without fiber breakage because meat, with its elastic-plastic properties, permits such shape shifts and / or only enables them to a limited extent with fiber breakage in the structure through high mechanical work. At no point does the meat pieces become completely destroyed. It flows off layer by layer parallel to the support surface on the perforated disc with its openings.

[0119] By the inventive coordination or targeted control of the speeds ni and / or n2 and / or n3 of the various screws of the device for optimizing the transport of the processed material in the conveying direction in the device according to the invention and for achieving the pressure specification value in the pre-shredding area, it is possible to achieve a reduced firmness state of the processed material, such as meat, in the pre-shredding area before the cutting area, which allows a cone formation of the processed material with greater power in the perforated discs of the cutting unit.

[0120] Such cone formations are deformations in a section of the material being processed, which has grown strength structures made up of materials of varying strength. Overcoming this strength structure requires a load that tears the bond in the fabric sections that lie directly on the perforated disk, or at least loosens it. Only then can cones in the crack area form freely into the holes. With the known state-of-the-art wolf screw geometry, backflow always occurs against the conveying direction, since the conveying efficiency of this type of screw is low at 30 to 50%, depending on the raw material, due to the material strength properties for generating thrust and is influenced by a higher counterpressure from the cutting unit. As a result, large portions of the conveyed quantities of the material being processed are not removed by the cutting unit in the cutting area.This creates a backflow of already contaminated and partially destroyed parts of the material to be processed beneath the screw in the support system, counter to the conveying direction. The use of the paired, blocking screw conveyors according to the invention in the transport area almost completely prevents such a backflow of the material to be processed. The sealing properties of the paired, blocking screw conveyors ensure that the material remains only in the pre-shredding area. The mixing processes of the screws ensure the strength-related change in the material state and the distribution of properties, which are prerequisites for penetration into the holes of the perforated disc.

[0121] The tightly bonded, natural, and highly elastic material structures of a processed product such as meat are broken down by deliberately controlled, volume-controlled conveying of the processed product and the use of paired, non-blocking pre-shredding screws. This allows the solid material structure to be heated and broken down by tearing at very low temperatures, such as in a frozen state, through the introduction of conveying energy from a backflow in the pre-shredding area and the refeed to the cutting unit.

[0122] It is intended that at least one rotating blade of the cutting unit arranged in the cutting area is connected to one of the two third drive shafts. Thus, the rotating blade in the cutting unit is set in rotation or a rotary motion by the drive motor of the third controllable drive unit in order to prepare the material to be processed.

[0123] It is also intended that the crushing of the processed material in the

[0124] The cutting area is pre-shredding with a predetermined working pressure, which triggers or selects specific components of the material to form cones in the openings of the perforated disc. For this purpose, the speed n2 of the locking conveyor screws is regulated accordingly. It is advantageous if the rotating blade in the cutting unit also rotates at the speed n2.

[0125] In this way, for example, a component of the material to be processed can be selectively selected, shredded with a correspondingly high quality in the cutting unit and output via the output area.

[0126] For such a material division of the grown raw material into its strength-related components for the production of defined end products with quality-determining material composition by pressure-dependent cone formation of the respective material types, a removal of the non-selected components of the processed material, for example from the pre-shredding area of ​​the device, is provided (not described in detail here).

[0127] The following are component-related, specified working pressures for the pre-shredding area:

[0128] - p = 6 to 10 bar soft materials, muscle meat and fats,

[0129] - p = 15 to 18 bar collagens,

[0130] - p = 20 bar and more skin components, tendons,

[0131] - p = 25 to 30 bar bone fragments and other residual components.

[0132] With these pressure settings it is possible to select components of the material being processed via the effect of working pressure and the size of the openings in the perforated disc.

[0133] 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:

[0134] Fig. 1: a device according to the invention for conveying and comminuting processed goods, Fig. 2: paired, blocking conveyor screws in the housing of the

[0135] Device in a sectional view,

[0136] Fig. 3: the locking screw conveyors according to the invention arranged in pairs without housing and

[0137] Fig. 4: a section of the transport area and the pre-shredding area of ​​the device for conveying and shredding processed materials.

[0138] Figure 1 shows a device 1 according to the invention for conveying and comminuting processed materials in an exemplary embodiment.

[0139] The device 1 has a housing 2 which comprises a receiving area 3 with a receiving opening 4, a transition area 5, a transport area 6, a pre-shredding area 7, a cutting area 8 and an output area 9 with an output opening 10.

[0140] A material to be minced, such as meat, is fed into the device 1 via the receiving opening 4 arranged in the receiving area 3, which in the example of Figure 1 is designed, for example, as a funnel-shaped receiving opening 4. The material to be conveyed and minced is not shown in Figure 1.

[0141] The material to be shredded reaches the receiving area 3 and is picked up by pairs of non-blocking screw conveyors 11 arranged in the receiving area 3, rotating at a speed ni, or is drawn into the winding flights of the non-blocking screw conveyors 11 and transported in a conveying direction 12 within the device 1. The screw conveyors 11 are designed as pairs of intermeshing, counter-rotating, non-blocking screw conveyors 11, which is not apparent from the side view chosen for Figure 1. The material to be shredded is conveyed by the pairs of non-blocking screw conveyors 11 from the receiving area 3 to a transition area 5.Within this transition area 5, which represents a transition in the housing 2 between the partially open receiving area 3 and the closed transport area 6, the non-blocking screw conveyors 11 can have a design of their winding flights that differs from the design of the non-blocking screw conveyors 11 in the partially open receiving area 3. This different design of the non-blocking screw conveyors 11 results from the different tasks in areas 3 and 5. While the non-blocking screw conveyors 11 in the receiving area 3 pick up the material to be shredded or must grip the material to be shredded with knife-like flight shapes and thus draw it in, in the transition area 5 the material to be shredded, which has already been picked up in the winding flights of the non-blocking screw conveyors 11, is conveyed in the conveying direction 12.Therefore, the outer diameter of the non-blocking screw conveyors 11 determined by the spiral flights may decrease in the transition region 5. Alternatively or additionally, the type of spiral boundaries 17 may change in the transition region 5.

[0142] From the transition area 5, the material to be shredded continues in the conveying direction 12 to the transport area 6. In this transport area 6, the material to be shredded is picked up by locking conveyor screws 13 rotating in pairs at a speed n2 and is conveyed or transported further in the conveying direction 12.

[0143] The blocking screw conveyors 13 are also designed as pairs of intermeshing, counter-rotating, blocking screw conveyors 13. The blocking screw conveyors 13 function like a displacement system with almost 100% efficiency in transporting the material to be processed in the conveying direction 12, without mechanically stressing the material. With these blocking screw conveyors 13, there is virtually no backflow of the material to be processed against the conveying direction 12 in the edge area between the blocking screw conveyors 13 and the conveyor housing 16 surrounding the blocking screw conveyors 13.

[0144] The blocking screw conveyors 13 are arranged in the transport area 6, surrounded by a conveyor housing 16. The blocking screw conveyors 13 and the conveyor housing 16 form a dynamic bearing system over part of the length of the housing 2. In this dynamic bearing system, outer surfaces 18 of the spirally wound boundaries 17 of the blocking screw conveyors 13 are designed to correspond to the conveyor housing 16 surrounding the outer surfaces 18 of the spiral boundaries 17 of the blocking screw conveyors 13. This means that the outer surfaces 18 of the spiral boundaries 17 form a sliding bearing with the conveyor housing 16. This sliding bearing serves to absorb deformation forces that occur on the screws during the material intake and can thus cause jamming of the knife drive pin in the tools.

[0145] The design of the sliding bearing is achieved by providing at least the spiral boundaries 17 of the blocking screw conveyors 13 and the conveyor housing 16 from a material having sliding properties. To this end, the material pairings between the two parts 13 and 16 are selected to create a sliding bearing pairing that virtually eliminates wear, with the dynamic bearing function being coordinated with the length of the blocking screw conveyors 13 and the number of spiral flights 17 within the conveyor housing 16. The outer surfaces 18 of the spiral boundaries 17 of the blocking screw conveyors 13 bear proportionally against the inner surfaces of the transport housing 16 and are supported in a sliding manner in the transport housing 16 during a rotational movement of the blocking screw conveyors 13, resulting in a supporting bearing effect during the working process of the device 1.

[0146] The length of the support zones, or the size of the sliding surfaces of components 17 and 16, influences the magnitude or level of the possible force absorption within the designed dynamic bearing system. This means that, if necessary, there can be shorter or longer support zones for these parts 17 and 16, which can then be installed and thus affect the geometry of the assemblies involved in the machine process as length adjustments.

[0147] Between the spiral boundaries 17 of the blocking screw conveyors 13, spiral-shaped flights 19 are formed, into which the material to be processed is received, coming from the overhang area 5 and transported through the transport area 6 to the pre-shredding area 7. Due to the sealing effect between the spiral flights 19 and the spiral boundaries 17 in an overlapping area of ​​the paired, blocking screw conveyors 13, a so-called shaft seal 29 is created, whereby the material to be processed can be transported very gently and continuously in the non-overlapping areas of the blocking screw conveyors 13 without the application of great pressure.

[0148] According to the invention, the rotational speeds ni, n2, and n3 can be adjusted independently of one another, whereby, for example, by varying the rotational speeds and n2, at least the pressure acting on the material to be shredded in the receiving area 3 and in the transport area 6 during conveying in the conveying direction 12 can be regulated. By changing the rotational speed ni, the pressure acting on the material to be shredded in the transition area 5 is also influenced.

[0149] For independent adjustment of the speeds n2 and n3, the paired, non-blocking screw conveyors 11 are connected to a first controllable drive unit 14, the paired, blocking screw conveyors 13 are connected to a second controllable drive unit 15 and the paired, non-blocking pre-shredding screws 20 are connected to a third controllable drive unit 21.

[0150] In the example, the first controllable drive unit 14 and the second controllable drive unit 15 each consist of a drive motor with adjustable speed, which is connected by means of appropriate power transmission belts or other technical means to the first drive shafts 32 of the non-blocking conveyor screws 11 and the second drive shafts 33 of the blocking conveyor screws 13, which are arranged parallel to one another, in order to generate a corresponding rotary movement. In the example of Figure 1, the third controllable drive unit 21 has a drive motor with adjustable speed, which is connected via a coupling 26 to the third drive shafts 35 of the non-blocking pre-shredding screws 20 in order to generate a corresponding rotary movement. Furthermore, it is provided that one of the third drive shafts 35 is connected to the cutting unit 24.It is intended that the second drive shafts 33 of the blocking screw conveyors 13, driven by the second controllable drive unit 15, are arranged or extend within the first drive shafts 32 of the non-blocking screw conveyors 11, driven by the first controllable drive unit 14, and thus within the interior of the non-blocking screw conveyors 11. Furthermore, the third drive shafts 35 of the non-blocking pre-shredding screws 20, driven by the third controllable drive unit 21, are arranged within the second drive shafts 33 of the blocking screw conveyors 13 and thus extend through both the non-blocking screw conveyors 11 and the blocking screw conveyors 13 of the device 1.

[0151] The material to be processed, transported by the locking conveyor screws 13 in the conveying direction 12, reaches the pre-shredding area 7. In this pre-shredding area 7, for example, pairs of non-locking pre-shredding screws 20 rotating at a speed of n3 are arranged for pre-shredding the material. Alternatively, only one non-locking pre-shredding screw 20 rotating at a speed of n3 can be arranged.The task of these non-blocking pre-shredding screws 20 is, on the one hand, to pre-shred the processing material in the pre-shredding area 7 and, on the other hand, to compact the pre-shredded processing material directly in the transition area between the pre-shredding area 7 and the cutting area 8, wherein the pre-shredded processing material is subjected to pressure and a so-called working pressure of the pre-shredded processing material is created directly in front of a perforated disc 22 having openings arranged in the cutting area 8.

[0152] Another possibility is to design the conveying process in conveying direction 12 with only a non-blocking pre-shredding screw 20 coupled to the blocking screw conveyors 13 in a replaceable screw housing equipped with support elements as a pre-shredding area 7 with possible backflow without its own drive. In this case, the output is determined by the non-blocking screw conveyors 11 and the transition area 5, which influence the filling level of the blocking screw conveyors 13. This conveying process option is used for soft processing materials where no temperature-related material strengths exist or are to be expected.

[0153] At least one pressure sensor 23 is arranged in the pre-shredding area 7, by means of which the current working pressure of the material being processed in the pre-shredding area 7 is measured. It can further be provided that a temperature sensor is arranged in the pre-shredding area 7, which detects the temperature of the pre-shredded material being processed in the pre-shredding area 7.

[0154] The measured values ​​of the working pressure and / or the temperature of the material to be processed in the pre-shredding area 7 are used to coordinate the speeds ni, n2 and n3 of the paired, non-blocking conveyor screws 11 in the receiving area 3, the paired, blocking conveyor screws 13 in the transport area 6 and the paired, non-blocking pre-shredding screws 20 in the pre-shredding area 7 in order to regulate the working pressure and / or the temperature of the material to be processed in the pre-shredding area 7. For this purpose, for example, the currently measured working pressure is compared with a specified pressure value and, if a deviation occurs whose magnitude exceeds a specified tolerance threshold, the speed ns is changed, for example. In this way, for example, the working pressure can be increased by increasing the speed ns and the working pressure can be decreased by decreasing the speed n3.Alternatively, for example, the rotational speed ni can be changed. Thus, for example, by increasing the rotational speed ni of the non-blocking conveyor screws 11 in the receiving area 3, more processing material can be drawn in and transported in the conveying direction 12, whereby the increased quantity of processing material conveyed into the pre-shredding area 7 increases the working pressure in the pre-shredding area 7, and vice versa.

[0155] The cutting unit 24 arranged in the cutting area 8 comprises at least one perforated disk 22 having a plurality of openings and a rotating blade 25. Alternatively, several perforated disks 22, each with an associated rotating blade 25, can be arranged one after the other in the cutting unit 24, which is not shown in Figure 1. The rotating blade 25 of the cutting unit 24 can rotate, for example, at a speed ns. For this purpose, the blade 25 is arranged on a third drive shaft 35 belonging to the first axis 27 or the second axis 28, which is connected to the third controllable drive unit 21.

[0156] The output area 9 is arranged after the cutting area 8 in the device 1 according to the invention. This output area 9 has an output opening 10 through which the material shredded in the cutting area 8 is removed from the device 1.

[0157] In the example of Figure 1, it is also provided that the paired, non-blocking conveyor screws 11, the paired, blocking conveyor screws 13, and the paired, non-blocking pre-shredding screws 20 are arranged on two parallel axes 27 and 28 in the device 1. Here, a first non-blocking conveyor screw 11, a first blocking conveyor screw 13, and a first non-blocking pre-shredding screw 20 are arranged on a first common axis 27 or axis of rotation, wherein a second non-blocking conveyor screw 11, a second blocking conveyor screw 13, and a second non-blocking pre-shredding screw 20 are arranged on a second common axis 28 or axis of rotation. The axes 27 and 28 are not shown in Figure 1.

[0158] The first controllable drive unit 14 transmits a rotary motion of the drive motor via a toothed belt 30, chains, or similar means to a worm gear 31, which is connected to two first drive shafts 32. These first drive shafts 32 are provided for transmitting a rotary motion to the non-locking screw conveyors 11. The worm gear 31 typically has a gear ratio of 1:14.5. A suitable power output for the first controllable drive unit 14 of the non-locking screw conveyors 11 in the receiving area 3 is 15 kW at a nominal speed of 1485 revolutions per minute.

[0159] The locking screw conveyors 13, arranged in pairs, are driven in the transport area 6 via second drive shafts 33. The second drive shafts 33 are connected to the drive motor of the second adjustable drive unit 15 via a multi-stage toothed belt drive 34. A suitable power output for the second adjustable drive unit 15 is 22 kW at a rated speed of 750 revolutions per minute.

[0160] The paired, non-locking pre-shredding screws 20 in the pre-shredding area 7 are driven via third drive shafts 35. For this purpose, the third drive shafts 35 are connected to the drive motor of the third controllable drive unit 21.

[0161] Since the drive shafts 32, 33 and 35 extend into one another or are arranged one inside the other on both the first axis 27 and the second axis 28, the various screws 11, 13 and 20 arranged in pairs can be operated at different speeds ni, n2 and n3.

[0162] It is provided that the at least one rotating blade 25 of the cutting unit 24 arranged in the cutting area 8 is connected to one of the two third drive shafts 35. Thus, the rotating blade 25 in the cutting unit 24 is set into rotation or a rotary motion by the drive motor of the third controllable drive unit 21.

[0163] In Figure 2, the locking conveyor screws 13 according to the invention, arranged in pairs in the housing 2 of the device 1, are shown in a sectional view.

[0164] The sectional view shows the transport area 6 of the device 1. The conveyor housing 16 can be seen in the housing 2. The arrangement of the paired, blocking screw conveyors 13 in the conveyor housing 16 in the transport area 6 forms the dynamic bearing system, in which the outer surfaces 18 of the spiral boundaries 17 of the blocking screw conveyors 13 are designed to correspond to the conveyor housing 16 surrounding the outer surfaces 18 of the spiral boundaries 17 of the blocking screw conveyors 13. In this case, the outer surfaces 18 of the spiral boundaries 17, together with the conveyor housing 16, form a plain bearing in a non-typical technical form with the functions described here.

[0165] The material to be shredded is transported in the free spaces formed by the interlocking, winding boundaries 17 of the locking screw conveyors 13, which are referred to as winding channels 19. A shaft seal 29 is formed between the paired, locking screw conveyors 13.

[0166] In Figure 2, it can be seen that a first blocking screw conveyor 13 of the paired, blocking screw conveyors 13 is arranged on a first axis 27, and a second blocking screw conveyor 13 of the paired, blocking screw conveyors 13 is arranged on a second axis 28. The axes 27 and 28 run parallel to one another in a longitudinal extension of the device 1.

[0167] In Figure 3, the paired, non-blocking conveyor screws 11 according to the invention in the receiving area 3 with the receiving opening 4, the paired, blocking conveyor screws 13 with the transport area 6 and the paired, non-blocking pre-shredding screws 20 in the pre-shredding area 7 are shown without the housing 2 and without the conveyor housing 16.

[0168] Also clearly visible are the winding boundaries 17 with the outer surfaces 18 and the winding flights 18 of the paired, blocking conveyor screws 13 as well as the respective arrangement of the screws on the first axis 27 and the second axis 28.

[0169] In the right-hand area of ​​Figure 3, narrow screw elements are shown which serve as ingress protection for the adjacent gear or other power transmission elements of the device 1 not listed here against penetration of the material to be processed from the receiving area 3 with a destructive effect, for example into the gear.

[0170] Figure 4 shows a section of the transport area 6 and the pre-shredding area 7 of the device 1 for conveying and shredding processed materials. In the transport area 6, the locking conveyor screws 13 are arranged in pairs and are arranged on the first axis 27 and the second axis 28 or rotate about these axes 27 and 28. In the example of Figure 4, only one non-locking pre-shredding screw 20 is arranged in the pre-shredding area 7 of the device 1. Variants in which the non-locking pre-shredding screws 20 are arranged in pairs are also possible.

[0171] The cutting area 8, arranged downstream of the pre-shredding area 7 in the conveying direction 12, is shown without the cutting unit 24 with at least one arranged perforated disc 22 and at least one rotating knife 25. The conveyor housing 16 surrounding the paired, blocking conveyor screws 13 in the housing 2 of the device 1 is also not explicitly shown to simplify Figure 4.

[0172] List of reference symbols

[0173] 1 Device for conveying and crushing processed materials

[0174] 2 housings

[0175] 3 Recording area

[0176] 4 Receiving opening

[0177] 5 Transition area

[0178] 6 Transport area

[0179] 7 Pre-shredding area

[0180] 8 Cutting area

[0181] 9 Output area

[0182] 10 Dispensing opening

[0183] 11 non-blocking screw conveyors

[0184] 12 Conveying direction

[0185] 13 blocking screw conveyors

[0186] 14 first controllable drive unit

[0187] 15 second adjustable drive unit

[0188] 16 conveyor casings

[0189] 17 winding boundaries

[0190] 18 Exterior area

[0191] 19 winding corridors

[0192] 20 non-blocking pre-shredding screws

[0193] 21 third adjustable drive unit

[0194] 22 hole disc

[0195] 23 Pressure sensor

[0196] 24 cutting unit

[0197] 25 rotating knife

[0198] 26 Clutch

[0199] 27 first axis

[0200] 28 second axle shaft seal timing belt worm gear first drive shafts second drive shafts timing belt gear third drive shafts

Claims

Patent claims 1. Device (1) for conveying and comminuting processed goods, comprising - a housing (2) comprising a receiving area (3) with a receiving opening (4) for feeding the material to be processed into the device (1), a transition area (5), a transport area (6), a pre-shredding area (7), a cutting area (8) and an output area (9) with an output opening (10) for removing a material to be processed shredded in the cutting area (8), - non-blocking screw conveyors (11) arranged in the receiving area (3) rotating in pairs at a speed ni for receiving and transporting the material to be processed from the receiving area (3) in a conveying direction (12), - locking screw conveyors (13) arranged in pairs in the transport area (6) and rotating at a speed n2 for further transport of the material to be processed in the conveying direction (12), - at least one non-blocking pre-shredding screw (20) rotating at a speed n2 and arranged in the pre-shredding area (7) for pre-shredding the material to be processed and for generating a working pressure, - a pressure sensor (23) arranged in the pre-shredding area (7) for measuring a working pressure of the material to be processed in the pre-shredding area (7) and - a cutting unit (24) arranged in the cutting area (8) for comminuting the material to be processed. The device (1) according to claim 1, characterized in that the housing (2) in the transport area (6) has a conveyor housing (16) which correspondingly encloses the paired, blocking conveyor screws (13) and forms a sliding bearing, wherein outer surfaces (18) of wound boundaries (17) of the blocking conveyor screws (13) are arranged to slide on the conveyor housing (16). Device (1) according to claim 2, characterized in that at least the winding boundaries (17) of the blocking conveyor screws (13) and the conveyor housing (16) are made of plastic, in particular of polyoxymethylene, polytetrafluoroethylene, or polyethylene. Device (1) according to one of claims 1 to 3, characterized in that the paired, non-blocking conveyor screws (11) are connected to a first controllable drive unit (14) via first drive shafts (32), that the paired, blocking conveyor screws (13) are connected to a second controllable drive unit (15) via second drive shafts (33), and that the at least one non-blocking pre-shredding screw (20) is connected to a third controllable drive unit (21) via a third drive shaft (35).Device (1) according to one of claims 1 to 3, characterized in that the paired, non-blocking conveyor screws (11) are connected to a first controllable drive unit (14) via first drive shafts (32), and that the paired, blocking conveyor screws (13) and the at least one non-blocking pre-shredding screw (20) are connected to a second controllable drive unit (15) via second drive shafts (33). Device (1) according to one of claims 1 to 5, characterized in that a temperature sensor for determining a temperature of the material to be processed in the pre-shredding area (7) is arranged in the pre-shredding area (7).Device (1) according to one of claims 1 to 6, characterized in that a cutting unit (24) is arranged in the cutting area (8), which cutting unit has at least one perforated disc (22) having a plurality of openings and at least one rotating knife (25) associated with the perforated disc (22), wherein the rotating knife (25) is connected to one of the third. Shafts (35) for transmitting a rotary movement to the rotating blade (25). Method for conveying and comminuting processing materials in a device (1) for conveying and comminuting processing materials according to one of claims 1 to 7, comprising the following steps: a) feeding a processing material to be conveyed and comminuted into a receiving area (3) via a receiving opening (4), b) drawing in the processing material to be comminuted into non-blocking conveyor screws (11) rotating in pairs at a speed n1 in the receiving area (3) and transporting the processing material in a conveying direction (12), c) transferring the processing material in the conveying direction (12) to a transport area (6), d) transporting the processing material to be comminuted through the transport area (6) by means of non-blocking conveyor screws (11) rotating in pairs at a speed n2,blocking conveyor screws (13) in the conveying direction (12) into a pre-shredding area (7) without backflow of the processing material within the transport area (6), e) generating a working pressure acting on the processing material to be shredded in the conveying direction (12) in a pre-shredding area (7) upstream of a cutting area (8) by means of at least one non-blocking pre-shredding screw (20) rotating at a speed n3 with simultaneous pre-shredding of the processing material in the pre-shredding area (7), f) shredding of the processing material by means of at least one perforated disc (22) arranged in the cutting area (8) having openings and by means of at least one rotating knife (25) arranged in the cutting area (8) and belonging to the perforated disc (22), g) removing the shredded processing material via a discharge opening, (10) of an output area (9), h) measuring a current working pressure acting on the material to be shredded in the pre-shredding area (7), i) comparing the measured current working pressure with a pressure setpoint and determining a deviation between the current working pressure and the pressure setpoint, and j) upon determining an amount of deviation between the current working pressure and the pressure setpoint above a predetermined tolerance threshold, at least one of the rotational speeds ni, n2, n3 is changed to achieve the pressure setpoint in the pre-shredding area (7). Method according to claim 8, characterized in that the quantity of material to be processed transported in the conveying direction (12) is controlled by controlling the rotational speed ni, where ni > n2 and / or n1 > n3. Method according to claim 8 or 9, characterized in that upon determining an amount of deviation between the current working pressure and the pressure setpoint above a predetermined tolerance threshold of 10%, the rotational speed n2 or the rotational speed n3 is controlled to achieve the pressure setpoint.Method according to one of claims 8 to 10, characterized in that a dynamic bearing system is provided in the transport area (6) of a device (1) in that a conveyor housing (16) is provided in the transport area (6) which correspondingly encloses a pair of blocking conveyor screws (13), wherein outer surfaces (18) of wound boundaries (17) of the blocking conveyor screws (13) are provided in a sliding manner on the conveyor housing (16) during a rotational movement of the blocking conveyor screws (13) and thus form a sliding bearing.Method according to one of claims 8 to 11, characterized in that non-blocking conveyor screws (11) arranged in pairs are driven via first drive shafts (32) by a first controllable drive unit (14) at a speed ni, that the blocking conveyor screws (13) arranged in pairs are driven via second drive shafts (33) by a second controllable drive unit (15) at a speed n2. and that the at least one non-blocking pre-shredding screw (20) is driven via a third drive shaft (35) by a third controllable drive unit (21) at a speed n3.

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