DE102022117372A1 - Toothed disc cleaner - Google Patents

Abstract

The invention relates to a toothed disc cleaner for cleaning pre-shredded plastic waste, in particular plastic flakes, by friction in the course of plastic recycling, comprising two mutually facing cleaning tools, of which at least one is rotationally driven by means of a rotary drive, the cleaning tools each having a work surface provided with cleaning teeth have, wherein an annular working gap for cleaning the plastic waste is delimited between the opposing work surfaces, and wherein the cleaning teeth of the opposing work surfaces mesh with one another, such that contaminants are removed from the plastic waste by friction, further comprising an inlet opening centrally into the working gap with a Entry device for entering the plastic waste to be cleaned, as well as an outlet provided on the outer edge of the working gap, through which the plastic waste pre-cleaned in the working gap is removed, the width of the working gap narrowing outwards in the radial direction in a first section starting from the inlet and that the width of the working gap is constant in a second section arranged radially outside the first section.

Description

The invention relates to a toothed disc cleaner for cleaning pre-shredded plastic waste, in particular plastic flakes, by friction in the course of plastic recycling, comprising two mutually facing cleaning tools, of which at least one is rotationally driven by means of a rotary drive, the cleaning tools each having a work surface provided with cleaning teeth have, wherein an annular working gap for cleaning the plastic waste is delimited between the opposing work surfaces, and wherein the cleaning teeth of the opposing work surfaces mesh with one another, such that contaminants are removed from the plastic waste by friction, further comprising an inlet opening centrally into the working gap with a Entry device for entering the plastic waste to be cleaned, as well as an outlet provided on the outer edge of the working gap, through which the plastic waste pre-cleaned in the working gap is removed.

A variety of extrinsic contamination can be found on the surfaces of plastic waste, including production waste, for example adhesive labels made of paper, plastic films or metal foils, printed layers of paint, possibly with a printed seal, metallization of the surface, adhesion of clay, sand, fats, oils and a variety of food residues. The focus of recycling into high-quality polymers, equivalent to primary plastics, is the almost residue-free removal of firmly adhering (extrinsic) coatings, be it with printing inks, with metallic vapor-coated surfaces or with adhesion promoters (adhesives).

For example, traditional washing technologies with cold or hot process water are used for cleaning. However, hot melt adhesives, printing inks and metal vapor coatings, for example, are not completely replaced. Complete detachment means residual contamination of less than 10 ppm, which only slightly causes so-called VOCs (Volatile Organic Components) during further thermal processing, such as extrusion or melting. With traditional caustic soda hot washes, for example, printing inks are only removed if surfactants specially adapted to the caustic soda are used and the flakes are penetrated in the wash for a long time. Removing hot melt adhesives is also problematic. The residual adhesion levels of at least less than 100 ppm required by the market are generally not achieved. This becomes noticeable when the recyclates are used, namely through gels in the film or a yellowish cast. Other serious consequences include outgassing during granulate extrusion or during further processing in LSP (Liquid State Polymerization), which condenses PET in a high vacuum.

The consequences of inadequate purification of just “clean” compared to “highly pure” seriously limit the use of recyclates and thus their marketing. At the same time, demands on the quality of the polymers are increasing, namely comparable to those of primary plastics. Products made from recyclates must be largely free of color impurities, various VOCs that pollute degassing and melt filtration in the extruder, and extrinsic contamination, as such remaining impurities can lead to adverse changes in the polymer properties in mechanics and processing as well as undesirable changes in color and odor .

Out of EP 2 094 462 B 1 is a method for separating pulp and other adhering substances when recycling waste plastic, in particular mixed plastic, known in which films and pieces of thicker plastic parts of possibly pre-sorted plastic waste are mechanically pre-shredded into flakes or particles up to a predetermined size and the shredded It is well added to a disk refiner together with water without first creating a compact or agglomerate from the flakes. Contaminants are largely rubbed off the flakes by the interacting disks of the disk refiner and are subsequently present as separate substances that can be separated from the plastic parts using a suitable separation process. Out of EP 2 094 461 B 1, a similar process is known.

Out of EP 2 734 302 B 1 is another method for removing contaminants on plastic chips using a disk refiner. The disk refiner is not a toothed disk refiner, but rather has a plurality of cleaning ribs extending between an inner and outer edge of the cleaning surfaces on the cleaning surfaces of the cleaning disks, with a plurality of cleaning webs running transversely to the direction of extension of the cleaning ribs being arranged between at least a few mutually adjacent cleaning ribs. At least one flank of the cleaning ribs is inclined or curved relative to the axial direction of the respective cleaning disk, and the cleaning webs each rise like a ramp and have a lower height than the cleaning ribs. In this way, the Cleaning achieves low mechanical stress on the plastic snippets by pulling them between the panes, in particular between the cleaning ribs, and preventing the plastic snippets from kinking, folding or tangled, which can lead to inadequate cleaning.

Out of EP 3 057 751 B1 In addition, a device and a method for cleaning plastic, in particular plastic shreds, are known in the course of plastic recycling. A toothed disc refiner is used with a central inlet for introducing the plastic to be cleaned into the working gap and an outlet provided on the outer edge of the working gap for the cleaned plastic together with rubbed off contaminants and water. The outlet has an outlet pipe through which, during operation, water flowing past the side of the working gap and directed tangentially to the working gap is pumped, which exerts a suction effect on the working gap, so that the cleaned plastic is conveyed into the outlet pipe. In this way, in addition to the entry and cleaning consistency, the discharge consistency can also be adjusted flexibly, in particular independently of the cleaning consistency. This makes it possible, in the interests of maximum energy efficiency and cleaning effect, to set a high solids consistency in the working gap and at the same time to set a suspension with a low solids consistency that can be easily conveyed or pumped downstream of the working gap.

With the known methods and devices, satisfactory cleaning of plastic waste can be achieved in most cases. A problem can lie in fluctuating entry consistencies, i.e. fluctuating solids proportions of the plastic waste when entering it together with a process liquid, such as water, into the working gap. In such cases, the plastic waste can be distributed unevenly, which in turn can have undesirable effects on the cleaning result.

Based on the prior art explained, the invention is based on the object of providing a toothed disc cleaner for cleaning pre-shredded plastic waste, which enables reliable and complete cleaning at any time.

The invention solves the problem through the subject matter of independent claim 1. Advantageous refinements can be found in the dependent claims, the description and the figures.

For a toothed disk cleaner of the type mentioned at the outset, the invention solves the problem in that the width of the working gap narrows in the radial direction outwards starting from the inlet in a first section and in that the width of the working gap in a second section arranged radially outside the first section is constant.

As explained at the beginning, the toothed disc cleaner is used to clean pre-shredded plastic waste, for example plastic flakes or plastic snippets shredded from plastic films, by friction, in particular by rubbing off contaminants from the surfaces of the plastic waste by means of the cleaning teeth of the opposite cleaning tools meshing with one another. In principle, the plastic flakes can be produced by shredding thin-walled hard plastics or films, etc. The contaminants to be removed can in particular be surface adhesions, such as cellulose, label residues, organic contamination, printed layers of paint, possibly with a printed seal, metallization of the surfaces, adhesive labels made of paper, plastic films or metal foils, etc. The toothed disc cleaner according to the invention comprises two cleaning tools facing each other which can be, for example, cleaning discs. At least one of the cleaning tools is driven in rotation by means of a rotary drive, so that a relative rotation occurs between the cleaning tools. The cleaning tools each have a work surface provided with cleaning teeth. The working surfaces are annular, in particular annular, with an annular, in particular annular working gap being delimited between the opposing working surfaces. The cleaning teeth of the opposite work surfaces engage with each other. The cleaning tools thus form a positive tool and a negative tool. The teeth on the work surfaces are individual teeth and are not connected to each other by ribs or similar. As explained in more detail below, it is possible for the cleaning tools to be adjusted axially relative to one another by means of a corresponding adjusting device (50), whereby the width of the working gap can be adjusted. In this way, depending on the plastic waste to be cleaned, sufficient friction can be achieved by the cleaning teeth for reliable and complete cleaning. The cleaning gap is formed by the distance between the cleaning teeth, in particular their side flanks and crown surfaces.

The toothed disc cleaner according to the invention is used to clean the pre-shredded plastic waste by friction. Become this way Contaminants are rubbed off the surfaces of the plastic waste. For this purpose, it is possible for a very small distance to be adjustable between the cleaning teeth of the opposing cleaning tools by means of appropriate axial adjustment until they come into contact with one another. For example, it is possible that the cleaning teeth can come into contact with the base of the opposite cleaning tool. A small distance can remain between the tooth flanks of the cleaning teeth, so that the plastic waste is forced over the tooth flanks to achieve an optimal cleaning result. The axis of rotation of the at least one rotatably driven cleaning tool, in particular the cleaning disk, can at the same time be the axis of symmetry of the cleaning tool, in particular the cleaning disk. An electric drive, for example, can be used as a rotary drive.

The toothed disk cleaner also has an inlet which opens centrally into the working gap, in an embodiment of the cleaning tools as cleaning disks, in particular in the axial direction of the cleaning disks, which at the same time forms the axis of rotation. An entry device is provided for entering the plastic waste to be cleaned into the working gap via the inlet. The entry device can feed the plastic waste together with a process liquid, such as water, into the working gap. For this purpose, a corresponding liquid supply device can be provided. However, a separate supply of the process liquid, for example water, into the working gap via a separate liquid supply device is also possible.

After entering the work gap, the plastic waste is cleaned between the opposing work surfaces in the work gap. The plastic waste, for example plastic flakes, is sheared between the cleaning tools and is thus distributed evenly in the working gap. The plastic waste passes through the rows of teeth formed by the cleaning teeth, whereby, if there is sufficient distance between the cleaning tools, further shearing of foil packages, for example, can occur. As a result of the friction exerted by the cleaning teeth on the plastic waste guided through the rows of teeth, contaminants on the surfaces are rubbed off or removed. In the course of the cleaning process, the plastic waste is transported radially outwards from the central inlet in the working gap and reaches the outlet provided on the outer edge of the working gap, via which the plastic waste is discharged together with the detached adhesions or contaminants and the process liquid for further processing .

According to the invention, it is provided that the width of the working gap narrows outwards in a first section in the radial direction starting from the central inlet, and that the width of the working gap is constant in a second section arranged radially outside the first section. The first section and the second section can in particular be a first ring section and a second ring section. The inlet zone formed by the first section serves to receive the amount of plastic waste material at the inlet. Due to the initially wider and then outwardly narrowing working gap in the first section, the plastic waste is homogenized and evenly distributed, even if the input consistency, i.e. the proportion of plastic waste per unit of time and/or per process liquid volume, fluctuates considerably. This homogenization and even distribution is crucial for subsequent cleaning success. Optimum cleaning can only be achieved if the plastic waste is transported outwards to the outlet as evenly and individually as possible along the rows of teeth formed by the opposite cleaning teeth.

The second section, in which the working gap width is constant, continues to be of crucial importance. Only the combination of the narrowing first section and the constant second section brings about the optimal cleaning result, in that the necessary homogenization and equalization of the plastic waste takes place in the first section and in the second section with a constant working gap width there is sufficient physical stress on the plastic waste for an optimal cleaning effect is achieved. The plastic waste, in particular plastic flakes, are thus aligned in the inlet zone formed by the first section parallel to the flanks of the cleaning teeth, thereby avoiding an accumulation or clumping of plastic waste, which would be harmful to cleaning. The necessary processing of the plastic waste for cleaning takes place in the work zone formed by the second section.

In particular, plastic flakes made from plastic films are difficult to dose for cleaning because they have a high dry and wet volume with a low bulk density. Due to the inventive design of the working gap with the first section and the inlet zone formed thereby, the cleaning tools can easily accommodate sinusoidally fluctuating dosages, for example, without causing additional damage game to clog. Thanks to the design of the working gap according to the invention, sandwich or film packages produced, for example, in the course of shredding plastic films, are also reliably broken down.

For optimal cleaning, it is crucial that plastic waste produced from foils by pre-shredding is passed over the cleaning teeth with its entire surface so that the surfaces are completely cleaned. The pre-shredding of the plastic waste is of particular importance in that the unfolding of accordion-like plastic flakes using the cleaning tools according to the invention and the dissolution of foil packages into individual flakes can lead to an extension of the pre-shredded plastic waste. In practice, for example, an average grain size of the pre-shredded plastic waste of not more than 50 mm, preferably not more than 25 mm, for example in the range of 20 to 25 mm, has proven to be effective. This allows complete friction of the entire surfaces of the plastic waste in the working zone formed by the second section to be achieved with practical dimensions of the cleaning teeth. The friction exerted by the opposing cleaning teeth ensures that contaminants, such as printing inks or metallized surfaces that are particularly difficult to clean, are completely removed. With the toothed disk cleaner according to the invention, a cleaning result can be achieved with extrinsic residual contamination of less than 100 ppm, preferably less than 10 ppm. This means that the recyclates produced according to the invention can be used like primary plastics for the production of plastic parts.

As explained, a process liquid, such as water, is usually additionally supplied to the working gap. Due to the inventive design of the toothed washer cleaner, significantly lower process fluid temperatures and a drastic reduction in the use of NaOH or surfactant admixtures are possible compared to the prior art.

According to one embodiment, the toothed disk cleaner can further comprise means for axially adjusting the cleaning tools relative to one another, so that the width of the working gap is adjustable, with the cleaning teeth of the cleaning tools being able to be brought into contact with one another in the second section. With this configuration, sufficient friction can be achieved for cleaning by the cleaning tools or the cleaning teeth, even for thin film waste. The cleaning teeth of the opposing cleaning tools can in particular engage with one another in a form-fitting manner.

According to one embodiment, the second section can directly adjoin the first section. In this way, the transition between the inlet zone formed by the first section and the working zone formed by the second section is optimized.

According to a further embodiment, the second section can extend to the outer edge of the working gap. The first section and the second section can together cover the entire working gap. However, it would also be conceivable that, for example, an inlet section is provided between the inlet and the first section, on which, for example, no cleaning teeth are arranged.

The working surfaces of the cleaning tools having the cleaning teeth can be arranged conically in the first section and parallel to one another in the second section. In this way, the first and second sections can be designed particularly simply.

According to a further embodiment, the cleaning teeth can be arranged on the surface sections of the working surfaces of the cleaning tools forming the first section at a greater distance from one another than on the surface sections of the working surfaces of the cleaning tools forming the second section. The density of the cleaning teeth per unit area is therefore lower in the first section than in the second section. This further simplifies the inlet of the plastic waste and further improves the homogenization and equalization as well as the separation of the plastic waste, while particularly effective cleaning takes place in the working zone formed by the second section due to the cleaning teeth that are arranged closer to one another.

The cleaning teeth of the cleaning tools can each have the shape of a shark fin in a side view. Furthermore, it can be provided that a leading edge of the cleaning teeth of the cleaning tools in the course of the relative rotation of the cleaning tools is arranged at an angle between 30° and 60° relative to the work surface carrying the cleaning teeth. It can also be provided that a flank of the cleaning teeth of the cleaning tools that trails in the course of the relative rotation of the cleaning tools is opposite to the flank that carries the cleaning teeth Work surface is arranged at an angle between 70° and 90°. If one speaks of a leading or trailing edge, this refers to the relative rotation of the cleaning tools, so that, for example, a non-rotating cleaning tool (stator) also has leading and trailing edges due to the relative rotation to an opposite, rotatingly driven cleaning tool (rotor). . The angle to the work surface is measured in the shortest direction. This design of the cleaning teeth, in particular the flatter bevel of the leading tooth flanks, enables particularly effective cleaning while at the same time optimizing the energy consumption of the toothed disk cleaner. The oblique design advantageously leads to an extended surface contact of the flexible plastic waste, in particular plastic flakes, which are aligned parallel, particularly in the second section, i.e. the work zone. In this way, a pumping effect can also be generated in a targeted manner, which effectively transports the plastic waste from the inlet through the working gap to the outlet, in particular conveying the plastic waste outwards sequentially from toothed ring to toothed ring. The cleaning teeth moving through the suspension of plastic waste and cleaning fluid create a flow caused by their shape. Due to the oblique design of the aforementioned tooth flanks, a pumping effect can be achieved in a targeted manner. The energy requirement of the toothed disk cleaner can also be reduced through optimal hydrodynamic design of the tooth flanks.

According to a further embodiment, at least one radially outer side flank of the cleaning teeth can be designed to be oblique relative to the work surface carrying the cleaning teeth. Furthermore, opposite side flanks of cleaning teeth that mesh with one another can run parallel to one another. Accordingly, the opposite, i.e. radially inner, side flank of the cleaning teeth can also be designed to be oblique relative to the work surface. The side flanks of a cleaning tooth can, for example, be designed to be mirror-symmetrical to one another, in particular in at least one rotational position of the cleaning tools relative to one another. The oblique arrangement can, for example, be at an angle between 10° and 30° to the respective work surface, again measured in the shortest direction. The cleaning teeth of a cleaning tool can have the same height. This applies accordingly to both cleaning tools, although the cleaning teeth of both cleaning tools can also have the same height. The cleaning teeth form a line so that plastic waste, in particular plastic flakes, can orient themselves parallel to the side flanks of the cleaning teeth. On the one hand, the pumping effect can be further improved through the aforementioned design of the lateral flanks of the cleaning teeth. On the other hand, the cleaning effect can be further optimized.

In principle, in order to achieve sufficient friction for cleaning, it is possible to make edges of the cleaning teeth, in particular edges between leading or trailing flanks and side flanks and/or between leading or trailing flanks and/or side flanks and a vertex surface of the cleaning teeth, sharp. On the other hand, in the course of cleaning according to the invention with the toothed disc cleaner, further shredding of the plastic waste, in particular tearing, is fundamentally undesirable, as this can worsen the cleaning effect and make it more difficult to convey away and later separate the cleaned plastic from the contaminants. Therefore, according to a further embodiment, it can be provided that at least one of the edges is between leading or trailing flanks and side flanks in the course of the relative rotation of the cleaning tools and/or at least one of the edges is between leading or trailing flanks and/or side flanks and an apex surface of the cleaning teeth is rounded. Such rounding prevents unwanted further shredding of the plastic waste. At the same time, it has been shown that the rounding leads to surface contact of the flexible plastic waste, such as plastic flakes, which is aligned parallel in the working zone formed by the second section.

In order to ensure sufficient friction at all times, even with rounded edges, the cleaning teeth, especially the rounded edges, can have a rough surface. Such a rough surface can be achieved in a particularly practical manner if the cleaning tools are stainless steel castings. The roughness can be caused by the design of the mold. At the same time, stainless steel is a very abrasion-resistant material, so the rough surface will not be rubbed smooth even over long periods of time. For example, if an alloy with high Brinell hardness is used, mechanical stress from the plastic waste does not lead to a loss of roughness. This ensures that the cleaning teeth can fulfill their cleaning effect, even over long periods of time.

As explained, at least one of the cleaning tools, preferably both cleaning tools, can have a cleaning disk be. The cleaning disk can, for example, be designed in the shape of a circular ring. It can, for example, be constructed from several circular ring segments. The axial direction then simultaneously forms the direction of rotation of the at least one cleaning disk. The inlet can then open into the working gap in the axial direction of the at least one cleaning disk.

According to a further embodiment, a leading edge of the cleaning teeth in the course of the relative rotation of the cleaning tools can have a convexly curved shape. The leading flank can extend from the working surface of the corresponding cleaning tool to a trailing flank of the cleaning teeth in the course of the relative rotation of the cleaning tools. The cleaning teeth can accordingly have a wedge shape with a convexly curved top. This configuration has proven to be particularly advantageous, on the one hand, for generating the pumping effect and, on the other hand, for an optimal cleaning result. Due to the curvature, each cleaning tooth has an inlet area for optimal alignment of the plastic waste, so that flakes, for example, can be optimally cleaned individually over the curved flanks. An extension of the leading flanks leads to more intensive cleaning. At the same time, the curvature improves the hydrodynamic flow and improves the pumping effect. Turbulence can also occur for hydrodynamic cleaning.

According to a further embodiment, it can be provided that the entry device comprises a liquid supply device through which a liquid can be fed directly into the entry device and/or that the working gap is assigned a liquid feed device through which a liquid can be fed directly into the working gap. The entry device can, for example, comprise a screw conveyor that conveys the plastic waste to the inlet. By means of a liquid supply device of the entry device, a process liquid, such as water, can be introduced directly into the entry device, for example the screw flight of a screw conveyor, in particular via suitable nozzles. As explained, it would also be conceivable for the working gap to be assigned a liquid supply device through which liquid can be fed directly into the working gap. For example, a screw conveyor could be designed as a hollow shaft screw and process liquid, such as water, could be introduced directly into the working gap via the hollow shaft. Of course, other entry options for the process liquid, in particular other nozzles for direct introduction into the working gap, would also be possible additionally or alternatively.

According to a further embodiment, it can be provided that the outlet comprises an outlet pipe connected to the working gap and leading to the outlet, the outlet pipe being connected to a liquid pump for pumping liquid through the outlet pipe, wherein in operation the liquid pump through the outlet pipe pumped liquid exerts a suction effect on the working gap in such a way that cleaned plastic waste is conveyed from the working gap into the outlet pipe. In this embodiment, an outlet pipe is provided at the outlet through which liquid, for example water, is pumped by means of a liquid pump, for example a water pump. The liquid jet pumped through the outlet pipe and in particular directed flows through the outlet pipe, preferably tangentially past the working gap, in particular a lateral outlet opening of the outlet. The liquid is delivered into the outlet pipe by the liquid pump via a liquid inlet opening. Two important functions are fulfilled by the liquid jet generated, which flows laterally past the working gap and is tangential to the working gap. On the one hand, the water jet transports the suspension conveyed from the working gap into the outlet pipe to an outlet. In addition, the directed liquid jet creates a suction effect in the working gap, which at least increases the transport of the suspension of cleaned plastic waste and impurities from the working gap into the outlet pipe. Especially when cleaning tools or cleaning teeth are placed closely together, a long residence time of the plastic waste in the working gap and optimal cleaning are achieved. However, the pumping effect of the toothed disc cleaner for radially conveying the plastic waste together with the process liquid through the working gap is reduced. The aforementioned configuration can ensure safe removal of the suspension of cleaned plastic waste and the process liquid even with a reduced pumping effect of the cleaning tools themselves. In this way, a reduced pumping effect due to a further optimized cleaning function of the toothed disk cleaner can be reliably compensated for. This is particularly important in conjunction with the inventive design of the working gap into two sections, in particular the second section with a constant distance between the cleaning tools, whereby this distance can be very small to achieve an optimal cleaning result.

The invention also solves the problem by using a toothed disk cleaner according to the invention for cleaning plastic flakes pre-shredded from plastic films by friction. The toothed washer cleaner according to the invention is particularly suitable for cleaning plastic flakes pre-shredded from plastic films. Cleaning results of less than 100 ppm, preferably less than 10 ppm, of extrinsic residual contamination can be achieved. It is important to maintain suitable solids consistencies in the working gap, for example less than 5% by weight for plastic flakes pre-shredded from plastic films. For PET or hard plastics in material transport, the solids consistency can be chosen to be slightly higher, for example no more than 10% by weight. It is also important to remove process liquid immediately so that re-contamination is avoided due to the cleaned plastic waste remaining for too long. As mentioned, when using a toothed disk cleaner according to the invention, grain sizes of the pre-shredded plastic waste of no more than 50 mm have proven to be practical.

In this regard, a further embodiment provides that the size of the plastic flakes corresponds to a maximum of twice the length, preferably a maximum of one length, of the tooth flanks of the cleaning teeth. This applies in particular to the tooth flanks that advance during rotation. Such a size of the plastic flakes ensures that the plastic flakes are guided completely over the cleaning teeth, in particular their flanks, at all times without the plastic flakes forming a sandwich or stack or becoming tangled. This would prevent complete cleaning.

• 1 eine Reinigungsscheibe eines erfindungsgemäßen Zahnscheibenreinigers in einer perspektivischen Ansicht,
• 2 die Reinigungsscheibe aus 1 in einer Draufsicht,
• 3 eine Schnittansicht entlang eines erfindungsgemäßen Zahnscheibenreinigers,
• 4 zwei Detailansichten einer Reinigungsscheibe des erfindungsgemäßen Zahnscheibenreinigers, und
• 5 ein erfindungsgemäßer Zahnscheibenreiniger in einer schematischen teilweise geschnittenen Darstellung,
• 6 der Zahnscheibenreiniger nach 5 mit einer Eintragseinrichtung zum Eintragen von zu reinigendem Kunststoffabfall nach einer ersten Ausgestaltung,
• 7 der Zahnscheibenreiniger nach 5 mit einer Eintragseinrichtung zum Eintragen von zu reinigendem Kunststoffabfall nach einer zweiten Ausgestaltung,
• 8 der Zahnscheibenreiniger nach 5 mit einer Eintragseinrichtung zum Eintragen von zu reinigendem Kunststoffabfall nach einer dritten Ausgestaltung, und
• 9 ein erfindungsgemäßer Zahnscheibenreiniger in einer schematischen geschnittenen Darstellung mit einem Auslass nach einem weiteren Ausführungsbeispiel.

An exemplary embodiment of the invention is explained in more detail below with reference to figures. It shows schematically:

• 1 a cleaning disk of a toothed disk cleaner according to the invention in a perspective view,
• 2 the cleaning disc 1 in a top view,
• 3 a sectional view along a toothed disk cleaner according to the invention,
• 4 two detailed views of a cleaning disk of the toothed disk cleaner according to the invention, and
• 5 a toothed disk cleaner according to the invention in a schematic, partially sectioned representation,
• 6 the toothed disc cleaner 5 with an entry device for entering plastic waste to be cleaned according to a first embodiment,
• 7 the toothed disc cleaner 5 with an entry device for entering plastic waste to be cleaned according to a second embodiment,
• 8th the toothed disc cleaner 5 with an entry device for entering plastic waste to be cleaned according to a third embodiment, and
• 9 a toothed disk cleaner according to the invention in a schematic sectional representation with an outlet according to a further exemplary embodiment.

Unless otherwise stated, the same reference numbers designate the same objects in the figures.

In the 1 and 2 a cleaning tool 10 of a toothed disk cleaner according to the invention is shown, in this case an annular cleaning disk 10, which can also be constructed, for example, from several annular segments. The cleaning disk 10 has an annular working surface 12 on which a large number of cleaning teeth 14 are arranged. The cleaning disk 10 centrally forms an inlet 16 for plastic waste to be pre-cleaned, for example plastic flakes made from pre-shredded plastic films. An outlet 18 for the pre-cleaned plastic waste is formed on the outer edge of the cleaning disk 10. An entry device for entering the plastic waste to be cleaned is connected to the inlet. The plastic waste can be introduced, for example, together with a process liquid such as water.

In 3 is the one in the 1 and 2 shown cleaning disk 10 as a lower cleaning disk 10 together with an upper cleaning tool 20, in this case an upper cleaning disk 20 shown. The upper cleaning disk 20 is also designed in the shape of a circular ring and has a circular working surface 22. On the work surface 22 of the upper cleaning disk 20 there are in turn a large number of cleaning teeth 24. By means of a rotary drive, at least one of the cleaning disks 10, 20 can be driven to rotate about its axis, so that a corresponding relative rotation between the cleaning disks 10, 20 is generated. The upper cleaning disk 20 is largely identical to the lower cleaning disk 10, with the difference that the rows of teeth formed from the cleaning teeth 24 are each arranged radially offset from the rows of teeth of the lower cleaning disk 10 formed from the cleaning teeth 14, so that the cleaning teeth 14 and Comb 24 together, as in 3 to recognize. In 3 It can also be seen that opposite side flanks 26, 28 of the cleaning teeth 14, 24 meshing with one another an axial adjustment device with which the cleaning disks 10, 20 can be adjusted axially relative to one another and can be brought into contact with one another, in particular in positive contact. By setting the cleaning teeth 14, 42 in a suitable, particularly closely spaced manner relative to one another, the friction required for an optimal cleaning result can be ensured. It can also be seen that the side flanks 26 of the cleaning teeth 14 and the side flanks 28 of the cleaning teeth 24 are each designed to be mirror-symmetrical and are arranged obliquely relative to the work surface 12 and 22 carrying the cleaning teeth 14 and 24, for example at an angle between 10 ° and 30°.

Especially in 3 It can also be seen that the working surfaces 12 and 22 of the cleaning disks 10 and 20, starting from the inlet 16, extend conically towards one another in a first section in the radial direction outwards, such that the working gap formed between the working surfaces 12, 22 is in this first Section narrows outwards in the radial direction starting from the inlet 16. In a second section adjoining the first section and continuing to the outlet 18, the working surfaces 12 and 22 of the cleaning disks 10 and 20 are arranged parallel to one another, so that the width of the working gap in this second section is constant. In 2 For illustrative purposes, reference number 30 is the circular dividing line between the in 2 radially inner first section and the radially outer second section. In the 1 and 2 It can also be seen that the cleaning teeth 14 are arranged on the surface section of the work surface 12 forming the first section at a greater distance from one another than in the outer surface section of the work surface 12 forming the second section. The tooth density of the cleaning teeth 14 is therefore less than in the first section in the second section. This is also the case with the upper cleaning disk 20.

Based on 4 The design of the toothed washer cleaner according to the invention will be explained in more detail. First is in the right view of 4 , in which only the lower cleaning disk 10 is shown in section, the cone angle 32 of the conical arrangement of the work surfaces 12 and 22 is shown in the first section. The left view in 4 represents a sectional view along line AA in the right view of 4 In particular, one of the cleaning teeth 14 can be seen there in a sectional view, with the direction of rotation of the cleaning disk 10 in the left-hand illustration 4 runs from left to right. A flank 34 of the cleaning tooth 14, which advances towards one another in the course of the relative rotation of the cleaning disks 10, 20, is arranged relative to the work surface 12 at an angle 36 between 30° and 60°, in this case approximately 45°. A trailing edge 38 of the cleaning tooth 14 in the course of the relative rotation of the cleaning disks 10, 20 is arranged relative to the work surface 12 at an angle 40 between 80° and 90°, in the present case approximately 85°. The apex surface 42 of the cleaning tooth 14 can be designed parallel to the working surface 12.

As in 4 Also visible in the left illustration, the cleaning tooth 14 has the shape of a shark fin in the side view. Edges between the different surfaces of the cleaning tooth 14, in particular the leading and trailing flanks 34, 38 and the apex surface 42 and/or between the leading and trailing flanks 34, 38 and the side flanks 26 and/or between the side flanks 26 and the apex surface 42 can be rounded. This also applies to the leading edge 34, which can be convexly curved, for example. All cleaning teeth 14 and 24 can be designed as shown in 4 shown as an example of one of the cleaning teeth 14.

It should also be mentioned that the cleaning disks 10, 20 can each be manufactured as a stainless steel casting.

In 5 are cleaning disks 10, 20, which can be designed, for example, like that 1 until 4 explained, arranged in a cleaner housing 44 so that they can rotate relative to one another. During operation, a rotary drive 46 can, for example, rotate the cleaning disk 20 via a rotary shaft 48, so that the cleaning disks 10, 20 execute a relative rotation to one another. The working gap between the cleaning disks 10, 20 can be adjusted via an adjusting device 50 comprising an adjusting drive 52 and an adjusting element 54.

Based on 6 until 8th Various options for introducing plastic waste to be cleaned into the toothed disc cleaner will be explained. In 6 the entry comprises an entry screw 58 driven via a screw drive 56, to which plastic waste 62 to be cleaned is fed via an inlet opening 60 and, on the other hand, a cleaning liquid 66, such as water, is fed by means of a pump 64. The cleaning liquid can basically be added via a screw entry, also via several inlets, into the entry screw 58 downstream of the inlet, via a hollow shaft of the entry screw 58 and/or via entry nozzles in the cleaner housing 44. The entry screw 58 conveys the plastic waste 62 together the cleaning liquid 66 centrally into the working gap formed between the cleaning disks 10, 20. The cleaned plastic waste is discharged via the outlet 18 for further processing, as in 6 shown at reference number 68.

The exemplary embodiment according to 7 differs from the exemplary embodiment 6 only in that instead of the entry screw 58, an entry funnel 70 is provided, which has several entry nozzles 72, for example distributed at regular intervals, on its upper edge. Cleaning liquid 66 supplied by the pump 64 is introduced into the entry funnel 70 via the entry nozzles 72, for example as a liquid jet onto an inner wall of the entry funnel 70, in which the supplied plastic waste 62 is located. Via a connection 74, the plastic waste 62 together with the cleaning liquid 66 are again fed centrally into the working gap between the cleaning disks 10, 20. Such an entry device is known, for example EP3 423 203 B1.

In the exemplary embodiment according to 8th an entry tank 76 with a stirring device 78 arranged therein is provided, into which the plastic waste 62 and the cleaning liquid 66 are fed. In the entry tank 76, the plastic waste 62 is mixed with the cleaning liquid 66. The plastic waste 62 mixed with the cleaning liquid 66 is in turn fed centrally into the working gap between the cleaning disks 10, 20 via a pump 80, as in 8th at 82 illustrated.

In 9 an outlet of a toothed washer cleaner according to the invention is shown as an example, wherein in 9 only the cleaner housing 44 of the toothed washer cleaner is shown in section with the outlet. In the 9 The embodiment shown corresponds, for example, to that in EP 3 057 751 B1 described configuration. The exemplary embodiment according to 9 can be combined with any of the previously explained exemplary embodiments.

In the example shown, an outlet pipe 84 adjoins the outlet 18 of the toothed disc cleaner tangentially in relation to the working gap between the cleaning discs 10, 20. Via a flange 86, the outlet pipe 84 can be connected directly or via another pipe to a separating device in which the cleaned plastic is separated from the contaminants rubbed off in the working gap. In the example shown, at the end of the outlet pipe 84 facing away from the flange 86 or the separating device, a nozzle pipe 88 is connected to a pump 90, in particular a liquid pump 90, for example a water pump 90, such as a centrifugal pump.

During operation of the toothed washer cleaner, the plastic cleaned in the working gap passes through the outlet 18 into the outlet pipe 84 due to centrifugal force together with rubbed-off contaminants and the cleaning liquid. At the same time, the liquid pump 90 pumps liquid, such as water, through the nozzle pipe 88 in the conveying direction from the The suspension emerging from the working gap is introduced into the outlet pipe 84 to the separating device in the form of a directed liquid jet, as in 9 illustrated at reference numeral 92. The directed liquid jet thus runs tangentially to the working gap, just like the outlet pipe 84. The liquid jet transports the mixture of cleaning liquid and cleaned plastic as well as abraded contaminants located in the outlet pipe 84 further to the separating device, as in 9 illustrated at reference numeral 94. The liquid steel exerts a suction effect on the working gap according to the principle of a jet pump in such a way that the suspension of cleaned plastic, rubbed off contaminants and cleaning liquid is sucked from the working gap into the outlet pipe 84. At the same time, the discharge consistency, i.e. the consistency in the outlet pipe 84, can be adjusted in a suitable manner by the liquid jet. A solids pump is not necessary, nor is a pump sump.

Reference symbol list

10

Cleaning disc

12

work surface

14

Cleaning teeth

16

inlet

18

outlet

20

Cleaning disc

22

work surface

24

Cleaning teeth

26

side flanks

28

side flanks

30

parting line

32

cone angle

34

Leading edge

36

angle

38

Trailing edge

40

angle

42

vertex surface

44

Cleaner housing

46

Rotary drive

48

rotating shaft

50

Adjustment device

52

Adjustment drive

54

Adjusting element

56

Worm drive

58

Entry snail

60

Inlet opening

62

Plastic waste

64

pump

66

cleaning fluid

68

Arrow

70

Entry funnel

72

Entry nozzles

74

Connection

76

Entry tank

78

Stirring device

80

pump

82

Arrow

84

outlet pipe

86

flange

88

nozzle pipe

90

pump

92

Arrow

94

Arrow

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2094462 [0005]
• EP 2094461 [0005]
• EP 2734302 [0006]
• EP 3057751 B1 [0007, 0048]
• EP 3423203 [0046]

Claims (20)

Toothed disc cleaner for cleaning pre-shredded plastic waste, in particular plastic flakes, by friction in the course of plastic recycling, comprising two mutually facing cleaning tools (10, 20), at least one of which is driven in rotation by means of a rotary drive (46), the cleaning tools (10 , 20) each have a work surface (12, 22) provided with cleaning teeth (14, 24), an annular working gap for cleaning the plastic waste being defined between the opposing work surfaces (12, 22), and wherein the cleaning teeth (14, 24 ) of the opposite work surfaces (12, 22) comb with each other, such that contaminants are removed from the plastic waste by friction, further comprising an inlet (16) opening centrally into the working gap with an entry device for entering the plastic waste to be cleaned, and one on the outer edge the outlet (18) provided in the working gap, through which the plastic waste pre-cleaned in the working gap is removed, characterized in that the width of the working gap narrows outwards in a first section in the radial direction starting from the inlet (16) and that the width of the Working gap is constant in a second section arranged radially outside the first section. Tooth washer cleaner Claim 1 , characterized in that it further comprises means for axially adjusting the cleaning tools (10, 20) relative to one another, so that the width of the working gap is adjustable, the cleaning teeth (14, 24) of the cleaning tools (10, 20) being in the second section Contact can be brought with each other. Toothed disc cleaner according to one of the preceding claims, characterized in that the second section directly adjoins the first section. Toothed disc cleaner according to one of the preceding claims, characterized in that the second section extends to the outer edge of the working gap. Toothed disk cleaner according to one of the preceding claims, characterized in that the working surfaces (12, 22) of the cleaning tools (10, 20) having the cleaning teeth (14, 24) are arranged conically in the first section and parallel to one another in the second section. Toothed disc cleaner according to one of the preceding claims, characterized in that the cleaning teeth (14, 24) are each arranged at a greater distance from one another on the surface sections of the working surfaces (12, 22) of the cleaning tools (10, 20) forming the first section than on the surface sections of the working surfaces (12, 22) of the cleaning tools (10, 20) forming the second section. Toothed disk cleaner according to one of the preceding claims, characterized in that the cleaning teeth (14, 24) of the cleaning tools (10, 20) each have the shape of a shark fin in a side view. Toothed disk cleaner according to one of the preceding claims, characterized in that a flank (34) of the cleaning teeth (14, 24) of the cleaning tools, which advances in the course of the relative rotation of the cleaning tools (10, 20), is opposite to the work surface (14, 24) carrying the cleaning teeth (14, 24). 12, 22) is arranged at an angle (36) between 30° and 60°. Toothed disc cleaner according to one of the preceding claims, characterized in that a flank (38) of the cleaning teeth (14, 24) of the cleaning tools trails in the course of the relative rotation of the cleaning tools (10, 20) relative to the work surface (14, 24) which supports the cleaning teeth (14, 24). 12, 22) is arranged at an angle (40) between 70° and 90°. Toothed disc cleaner according to one of the preceding claims, characterized in that at least one radially outer side flank (26, 28) of the cleaning teeth (14, 24) is designed to be oblique relative to the work surface (12, 22) which supports the cleaning teeth (14, 24). Toothed disk cleaner according to one of the preceding claims, characterized in that opposite side flanks (26, 28) of cleaning teeth (14, 24) which mesh with one another run parallel to one another. Toothed disk cleaner according to one of the preceding claims, characterized in that at least one of the edges is between leading or trailing flanks (34, 38) and side flanks (26, 28) in the course of the relative rotation of the cleaning tools (10, 20) and/or at least one of the Edges between leading or trailing flanks (34, 38) and / or side flanks (26, 28) and a vertex surface (42) of the cleaning teeth (14, 24) are rounded. Toothed disk cleaner according to one of the preceding claims, characterized in that a flank (34) of the cleaning teeth (14, 24) which advances in the course of the relative rotation of the cleaning tools (10, 20) has a convexly curved shape. Toothed disk cleaner according to one of the preceding claims, characterized in that the cleaning tools (10, 20) are stainless steel castings. Toothed disc cleaner according to one of the preceding claims, characterized in that at least one of the cleaning tools (10, 20) is a cleaning disc (10, 20). Tooth washer cleaner Claim 15 , characterized in that the inlet (16) opens into the working gap in the axial direction of the at least one cleaning disk (10, 20). Toothed disc cleaner according to one of the preceding claims, characterized in that the entry device comprises a liquid supply device through which a liquid can be fed directly into the entry device and / or that the working gap is assigned a liquid feed device through which a liquid can be fed directly into the working gap . Toothed disk cleaner according to one of the preceding claims, characterized in that the outlet (18) comprises an outlet pipe (84) connected to the working gap and leading to the outlet, the outlet pipe (84) being equipped with a liquid pump (90) for pumping liquid through the Outlet pipe (84) is connected, wherein during operation the liquid pumped through the outlet pipe (84) by means of the liquid pump (90) exerts a suction effect on the working gap such that cleaned plastic waste is conveyed from the working gap into the outlet pipe (84). Use of a toothed disc cleaner according to one of the preceding claims for cleaning plastic flakes pre-shredded from plastic films by friction. Use after Claim 19 , characterized in that the size of the plastic flakes corresponds to a maximum of twice the length, preferably a maximum of one length, of the tooth flanks of the cleaning teeth (14, 24).

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