DE10103990A1 - Device for cleaning thermoplastic material - Google Patents

Abstract

The device for removing solid impurities from thermoplastic synthetic materials comprises a housing (1) with a feed channel (3) for the material which is to be purified and a discharge channel (5) for purified material. A filter band (7) penetrates the flow path of the material in the housing (1) in a sealed manner between the feed channel (3) and the discharge channel (5); said filter band being able to be displaced in the longitudinal direction thereof and used to separate the solid impurities. A support body (11) with a plurality of through channels arranged next to each other for through flow of the purified material to the discharge channel (5) is disposed in the flow path on the side of the filter band (7) facing the discharge channel (5). Sealing means (27,29) are provided in the region of the filter band inlet (23) and in the region of the filter band outlet (25). The sealing means seal the filter band (7) in relation to the housing (1). The filter band (7) is continually or gradually advanced by means of a conveyor device (43). The sealing means of the filter band outlet (25) cool the impurity load (19) of the filter band (7) containing a proportion of thermoplastic material in an at least approximate manner until solidification occurs. A controllable blocking device (35) is disposed on the outlet (25) of the filter band, whereby said device modifies the size of the cross-section of the filter band outlet (25) and the size of the cross-section of the filter band (7) provided with the load of impurities (19) in order to block or release the advance movement of the filter band (7) in relation thereto.The blocking device can comprise a blocking piston (37) which controllably narrows the dimension of the outlet, or the blocking device can comprise a motor driven tool, e.g. a milling cutter, which reduces the cross-section of the impurity load to a value which is smaller than that of the cross-section of the filter band outlet (25).

Description

For cleaning thermoplastic material, it is an example from WO 98/31527, but also from CH 469 547, DE 199 16 539, DE 19 44 704 and FR 2 332 113 are known, up to a viscous enamel condition softened plastic material by a close-knit, for example to press filter mesh made of wire mesh, which adheres to one with a large number of comparatively large openings provided support supports to the high pressing pressure in practice to be able to record. The filter belt is in the area of the support body the contamination of the plastic melt and gradually or shifted continuously, reducing the pollution load is transported and unloaded areas of the filter belt over the support body to be moved.

In the known cleaning devices, the filter band penetrates in its longitudinal direction slidably in a housing of the device flows running between a feed channel and a discharge channel path of the thermoplastic material. The housing must be in the Area of its filter band inlet and in the area of its filter band outlet be sealed against the filter belt to prevent the Plastic melt due to the high internal pressure along the filter bands ooze out of the case.

In conventional cleaning devices are at the filter belt inlet and Cooling devices are provided at the filter belt outlet that hold the plastic cool the melt in these areas until it solidifies. The The resulting plastic plugs seal the filter band inlet and the filter band outlet sufficiently tight.  

As long as the plastic melt is under the extruder pressure, that is Filter belt exposed to very high frictional forces, so that it does not or is very difficult to move. This applies in particular if the Plastic melt in the area of the filter belt inlet and the filter b form solidified plastic drops on the outlet for sealing. To the To facilitate filter belt transport, it is known to print in art molten material for the duration of the filter belt transport either by Ab switch the extruder or by depressurizing the melt in the Lower the cleaning device housing (DE 35 35 491 C1).

It is also known that the area, in particular of the filter belt outlet, to heat the filter belt feed and thus the sealing plug to soften. However, it has been shown that such a thermal Control of the sealing works only comparatively slowly, which the Filter change times increased undesirably. This is particularly so then disruptive when plastic recycling material is very dirty should be cleaned and the filter belt ge in relatively short intervals needs to be changed. Around the filter belt inlet and the filter belt To be able to provide sufficient thermal sealing in practice is one absolutely precise and fast temperature change at the filter belt inlet and Filter belt outlet required. Especially at the filter belt outlet this requirement change due to the pollution load the material composition, especially for short filter changes vallen difficult to meet. This is not least because of the temperature Changes in plastic are slow.

Attempts were also made to filter the filter band inlet and the filter band outlet to be sealed by hydraulically operated sealing strips that hold the filter Pinch the tape tightly. It has been shown that in particular the edges of the filter tape cannot be sealed leak-free. Prevent larger dirt particles contained in the plastic melt that the sealing strips are pressed tightly against the filter band  can. In addition, in the high pressure, highly viscous material a high tech effort required.

The general aim of the invention is the cleaning performance of a device for cleaning solid materials from thermoplastic material to increase with comparatively simple technical means.

In a first aspect, the object of the invention is to achieve this goal reliable and quickly effective sealing of the filter belt to reach.

The invention relates generally to a device for cleaning thermoplastic material, in particular plastic material, from solid contaminants, comprising:

• - A housing with a feed channel for the material to be cleaned and a discharge channel for the cleaned material,
• - A the flow path of the material in the housing between the Feed channel and the discharge channel sealed penetrating, in its longitudinally displaceable filter belt for separating the Solid impurities,
• - One on the side of the filter belt facing the discharge channel arranged in the flow path support body with a variety of ne beneath arranged passage channels for the passage of the cleaned material to the discharge channel;
• - The housing in the area of its filter belt inlet and in the area of its filter band outlet sealing against the filter band Sealant and
• - Means for the gradual or continuous feed of the Filter bands.

In the first aspect, the above object is invented solved according to the invention in that the sealing means of the filter band outlet ses the impurities containing a portion of thermoplastic material supply load of the filter belt at least approximately until it solidifies cool condition and that at the filter belt outlet a the cross-section size of the filter band outlet and the cross-sectional size of the with the solidified filter load to block or Release the feed movement of the filter belt relative to each other ver changing, controllable blocking device is provided.

The invention is based on the consideration for sealing the Filter belt outlet formed, solidified plastic drops for the pre not to thermally soften the shear motion of the filter belt as before, but the plastic material in this area solidifies let and instead the mechanical blocking of the frozen art pick up material. A blocking device of this type can be lock or unlock very quickly, so that the filter belt feed also in short successive intervals without affecting the seal effect can be carried out what the cleaning performance of the inventions device according to the invention increased.

The blocking device can be operated by a controllable actuator, for example, a hydraulic pressure cylinder, transverse to the feed direction of the filter belt towards or from the contamination load of the filter belt this include movable stamp. The stamp works here against the solidified area of the pollution load, so has different than with conventional sealing strips no sealing function, which with conventional Lichen closure strips of the type explained above to problems has led. To the clamping effect of the on the side of the contamination freight attacking stamp, this can on his Ver side facing the cleaning load, clamping projections or The like, which may be in the plastic material  dig. The infeed movement of the stamp may be one movement perpendicular to the filter belt may be superimposed on it Stamp allowed, saw-like or planed in the solidified verunreini a freight recess for receiving the stamp to work. For this purpose, the clamping projections can be in the direction of saw continuously or oscillating overlay movement be tooth-like or knife-like.

In the embodiment explained above, the stamp provides for Narrowing of the cross section of the filter belt outlet in the area the solidified pollution load. However, since the stamp in this Embodiment essentially do not perform a sealing function the sealing problems explained above are eliminated more conventionally Sealing strips.

In another preferred embodiment, the outlet cross is not section of the filter band outlet enlarged to release the filter band, but it becomes the cross section of the contaminant load of the filter belt relative to the specified outlet cross section of the filter belt outlet reduced this purpose. In this embodiment it is provided that the filter belt outlet is the contaminant load in the feed direction of the filter band has a constricting constriction and that the blocking device on the solidified contamination load of the filter belt little at least except for a cross section that can be moved past the constriction load-bearing, in particular motor-driven tool. at the tool can be a translationally movable planer or Act milling tool. However, a rotating milling cutter is particularly suitable tool whose axis of rotation is transverse to the feed direction of the filter belt and the pollution load runs parallel to the level of the filter bands. The milling tool reduces the height of the filter tied up charged pollution load until it narrowed of the filter belt outlet can happen.  

The narrowing can be, for example, stationary on the fil act narrowing rib provided or the like. The narrowing can also be formed by the tool itself.

If the tool for the intermittent feed of the filter belt equally is only put into operation intermittently, it can be under Circumstances with the pollution load of the Bake filter tapes in a form-fitting manner. The holding forces that occur can be so large that the tool can be restarted in individual cases drive is impossible or only possible with very high drive power becomes. In order to prevent this, a preferred embodiment provides seen that the tool for starting his drive in the Essentially completely out of engagement with the pollution load is feasible. The tool is expediently used during the filtering phase the device is lifted from the solidified contamination load and only after starting up again against the pollution load delivered.

Due to different cross sections at the filter belt inlet and filter bandausiass there can be hydrostatic pressure differences in the viscous Material melt come, which is used to transport the filter belt can be. The resulting feed forces are more normal do not show, so that additional transport facilities, for example hydraulic, clamping to the filter belt outside the housing gripping transport devices are required. Examples of such Transport devices are described in WO 98/31527, among others. However, the hydrostatic difference can be deliberately kept to by activating the additional transport device, the filter belt trans port regardless of material properties of the melt can. Under a second, also with other cleaning devices as the aspect which can be used as the cleaning device explained above the invention, it is an object of the invention to show a way how  the transport of the filter belt is easier than before leaves.

In the second aspect of the invention it is provided that the feed channel for the material to be cleaned in the feed direction of the filter bands essentially over the entire ver, with through channels see area of a support surface of the support body supporting the filter band pers extending material distribution section and one in the Leading into the housing, opening into the material distribution section Material supply section includes and that the material supply section cut against the direction of advance of the filter belt against the Center of the feed direction related to the passage channels Area of the support surface of the support body offset in the material distribution section ends.

In conventional cleaning devices, such as in WO 98/31527 are described, the material feed section opens centered in the material distribution section to ensure even distribution of the material to be cleaned on the support supported on the support body to reach the area of the filter belt. In contrast is the material lead section preferably in the area of the counter feed Direction of the filter belt located end of the material distribution section offset, so that this under high pressure in the material distribution cut inflowing material to be cleaned due to its highly viscous Properties in the feed direction a driving force on the filter belt exercises. By simply moving the material feed section achieve that the filter belt even during cleaning operation can be transported. To the increasing distance from the material aluminum supply line section due to the outflow of material through the filter belt decreasing material volume flow in the material distribution section Expediently provided that the material distribution section tapers in the direction of advance of the filter belt, in particular tapers continuously.  

In conventional cleaning devices, such as those made of WO 98/31527 are known, the support body has at least in the area of its support provided with passage channels and supporting the filter belt surface a large number parallel to each other and in the direction of displacement of the Filter bands extending grooves, open to the support surface, by wel chen the passage channels run out. The passage channels are with the known support body as extending transversely to the grooves, in longitudinal direction stepped bores formed, which the grooves to form Cut connection holes. In the end, these connecting holes go gen in transverse to it in an end face of the support body molded transverse channels that lead to a common, the cleaned material Open the collecting channel. The production of such channels is comparative wise elaborate. In addition, with such channels Reduce the surface roughness of their channel surfaces only to a limited extent.

In a third aspect of the invention, which in turn also in others advantageously used as the cleaning devices explained above can be set, the flow resistance should be achieved, which the cleaning device opposes the plastic melt, can be reduced by a technically simple measure.

In this aspect of the invention it is provided that the support body the filter, at least in the area of its passage channels tied support surface a variety of parallel and in front thrust direction of the filter belt extending towards the support surface has open grooves from which the passage channels start, and that the support body to form the passage channels a variety of cylin drischer, first connecting bores extending transversely to the grooves contains the connecting holes connected to the crossed grooves are. In addition to these known measures, however, is before seen that each of the first connecting holes via at least one second one running in the support body transverse to the first connecting bore,  cylindrical connecting hole is connected to a collecting channel and that at least the first and the second connecting holes have polished bore surfaces.

In contrast to the support body of the conventional cleaning device are all of the sections running within the support body Connection channels formed as cylindrical bores, which are in Contrary to groove-shaped sections of connecting channels of the conventional support body with rotating polishing tools have it polished. It has been shown that by polishing the connection channels the flow resistance that the highly viscous plastic melt finds, can be significantly reduced, which also for the Extrusion pressure to be applied to the cleaning process can be reduced. Expediently there are several along each first connection bore second connecting holes arranged distributed, which also the conventional support bodies required for the end connection, however, it is difficult to produce radially staggered stepped bores be avoided.

The first connecting bores can, as before, the grooves for formation cut the connection holes. Advantageously, however, is provided hen that the first connecting holes across across the support surface drilled, especially also polished holes with the grooves ver are bound. Such a support body is extraordinary Lich stable in the area of its support surface and still has its Support surface distributes approximately uniform material drainage properties.

It is understood that the grooves and / or the collection channel for reduction the flow resistance of the highly viscous plastic melt if you have polished wall surfaces.  

In all the variants of the invention mentioned above, the Areas of the support surface containing grooves can be divided into partial areas, in which the grooves arranged there are transverse to their longitudinal direction Gap are offset to prevent the filter belt from partially through the webs forming support surfaces between the grooves is blocked. The area of the support surface of the support body provided with the passage channels pers can be flat or in the feed direction in a manner known per se be convexly curved. In particular, the support surface, as shown in WO 98/31527 is explained to be semi-cylindrical in order to at gerin high cleaning performance due to the dimensions of the cleaning device to reach.

From DE 199 16 539 A1 it is known to train the filter belt in multiple layers the so that there is an endless support layer adjacent to the support body and one lying on the support layer on the side facing away from the support body ing filter layer, the filter layer is finer mesh than that Support layer. This well-known idea can also be found within the Aspects of the invention explained above advantageously use, since they the Operating costs of the cleaning device are reduced. For the more finely meshed Filter layer can be a simple wire filing that can only be used once Use tere fabric, while the endless support layer is made of mecha nisch stable but expensive "armored fabric tape" can exist. There primarily the filter layer is loaded with the pollution load, can most of the contaminant load along with the filter layer be removed from the support layer, which makes cleaning the circumferential support layer considerably simplified.

In the cleaning device known from WO 98/31527 this has the Housing containing support body has a removable side wall that follows Type of a cover can be removed to remove the filter belt to be able to. Given the high pressure of the plastic melt, which the housing must withstand, the side wall with the rest  be screwed tightly to the housing. In addition, run in the Sidewall in the rest of the housing and thus sealing ting channels for a heating or cooling fluid. Disassembly and assembly of the Accordingly, the side wall is complex and is additionally created by the comparatively large weight of the side wall difficult. To the filter To be able to change the band easier than before is a preferred one Design provided that the housing along an edge of the Filter bands one reaching up to the filter band, over the entire extend within the housing extending portion of the filter belt has the slot, which is removable by a one-part or multi-part Bar is closable. Because of the comparatively small slot wide, the pressure forces acting on the bar are comparatively low, which simplifies the design and fastening of the bar. Cold and Heating medium ducts can easily be laid outside the bar.

In the following, exemplary embodiments of the invention are to be explained using a Drawing will be explained in more detail. It shows:

Figure 1 is a schematic side view of an apparatus for cleaning thermoplastic plastic material from solid contaminants.

Fig. 2 is a sectional view through the cleaning device, seen along a line II-II in Fig. 1;

Fig. 3 is a view of a support surface provided in the cleaning device of Figure 1 supporting body, seen along a line III-III in Fig. 2.

Fig. 4 is a sectional view of a variant of a device for cleaning thermoplastic material and

FIG. 5 shows a detailed view of the device, seen along a line VV in FIG. 4.

The device shown in Figs. 1 and 2 for cleaning thermoplastic plastic material from solid contaminants, such as metal waste or the like, has a housing 1 , the plastic material to be cleaned with a high pressure in a highly viscous state, for example from an extruder press or the via a feed channel 3 same is fed. The cleaned material is discharged through a discharge channel 5 . The flow path between the feed channel 3 and the discharge channel 5 passes through sealed in the housing 1, a multilayer filter belt 7 , which will be explained in more detail below, which on its side facing away from the feed channel 3 in the flow path of the plastic melt on a side inserted into a chamber 9 of the housing 1 standing support body 11 rests to absorb the high pressure of the plastic melt. The support body 11 has a plurality of passage channels generally designated 13, which emanate from its flat support surface 15 and lead into a collecting channel section 17 of the guide channel 5 .

During the cleaning process, the filter belt with a 7 loads indicated at 19 impurity cargo conditions from the Festkörperverunreini and comprises a proportion of plastic melt. In order to prevent clogging of the filter belt 7 , the filter belt 7 is moved continuously or stepwise in the direction of an arrow 21 ( FIG. 1) and the contaminant load 19 is thus transported out of the housing. The filter band 7 occurs unloaded on a slit-like narrow Filterbandein let 23 in the housing 1 and at a likewise narrow slit-like filter band outlet 25 . In order to be able to seal the filter band 7 against the high pressure prevailing in the plastic melt, the filter band inlet 23 and the filter band outlet 25 are connected to coolant lines 27 and 29 , here in the form of coolant flow-through cooling channels, which the plastic melt or Cool the plastic portion of the contamination load 19 in the area of the filter belt inlet 23 and the filter belt outlet 25 to the solidification temperature. The filter band inlet 23 and the filter band outlet 25 are therefore sealed by "plastic plug". The housing 1 are assigned to the remainder of a heat transfer medium-carrying heating channels 31 and the housing 1 is isolated by isolation means 33, here in the form of heat insulation slots thermally outlet of the Kühlzonene at the filter band inlet 23 and the filter band 25th It goes without saying that the housing 1 can also be heated in some other way, for example by means of electrical heating means.

The inlet slot of the filter belt inlet 23 widens in the feed direction of the filter belt 7 , so that the solidified plastic plug is drawn into the heated area of the housing 1 during the feed movement of the filter belt 7 and melts there again.

The outlet cross section in the area of the filter belt outlet 25 is larger than the inlet cross section in the area of the filter belt inlet 23 . Due to the cross-sectional difference, a static differential pressure acts, which tries to press the filter belt 7 in the feed direction 21 . A controllable blocking device 35 block the ejection movement of the cooled by the cooling means 29 before reaching the Filterbandauslasses 25 Erstar annealing temperature and solidified into a substantially rigid plug impurity load of the filter band. 7 The outlet cross section in the solidification area of the filter band outlet 25 has a constant cross section in the feed direction, but preferably a cross section which widens slightly in the feed direction, so that the contaminant load can also be discharged in the solidified state.

In the exemplary embodiment in FIG. 1, the blocking device 35 has a punch 37 arranged on the side of the contamination load 19 , which extends in the form of a strip across the filter belt 7 and is pressed or pressed by a hydraulic cylinder 39 to block the feed movement against the solidified contamination load is released from the feed movement to release it. The punch 37 has sawtooth-shaped clamping projections 41 in the feed direction, with which it is able to penetrate into the solidified contamination load of the filter belt 7 while reducing the outlet cross-section of the filter belt outlet 25 available for the passage of the filter belt 7 and its contamination. In order to facilitate the penetration of the clamping projections 41 into the solidified contamination load, the stamp 37 can optionally be heated locally.

The cross-sectional difference between filter band inlet 23 and filter band outlet 25 could be selected to be so large that the filter band is only displaced by the hydrostatic differential pressure. However, in order to be able to control the advance movement in a targeted manner and, if necessary, to compensate for differential pressure fluctuations, which may result, for example, from the viscosity of the plastic material, an additional transport device 43 is provided, which has a hydraulically closable clamping jaws 45 on the filter belt 7 including its contamination load is able to attack and the filter belt 7 is gradually moved in the feed direction 21 . The clamping jaws 45 are guided on a guide 47 so as to be displaceable in the feed direction 21 and are moved back and forth by a hydraulic cylinder 49 . Further individual units of such a transport device are explained in WO 98/31527, to which reference is made for this.

Instead of the transport device 35 , but preferably additionally, the material flow of the highly viscous plastic melt supplied via the feed channel 3 is used to support the feed movement of the filter belt 7 . For this purpose, the feed channel 3 comprises a material distribution section 51 which extends over the entire support surface 15 of the support body 11 and into which the material to be cleaned is fed via a material feed section 53 in the region of the end of the material distribution section 51 adjacent to the filter band inlet 23 .

From this, the feed direction 21 situated the end of the material distribution portion 51 opposite to the Materialverteilungsab tapering section 51 in the feed direction of the filter belt 7 at least in the region of the support body 11, but preferably, however, up to or near the beginning of the cooling zone 29 of the Filterbandauslasses 25th The plastic melt therefore essentially flows exclusively in the feed direction of the filter belt 7 and, due to its high viscosity, takes the filter belt 7 in the feed direction. Since the material distribution portion 51 is tapered in the feed direction of the material discharge is passed balanced feed direction in front of the filter band through 7 in the sense of homogenization of the material flow.

A hooking of the filter band to prevent 7 with edges of the through passages 13 and accordingly to keep the necessary for advancing the filter tape 7 forces as small as possible, 15 contains the support surface of the support body 11, a plurality in the feed direction 21 extend the mutually parallel grooves 55, the passages 13 emanate from the bases thereof, which are recessed relative to the supporting surface 15 . The support surface 15 is accordingly formed by the ribs 57 remaining between adjacent grooves 55 . Similar to the support surface construction known from WO 98/31527, here too, the grooves 55 are arranged in two successive sections in the feed direction of the filter belt 7 offset transversely to the feed direction to a gap, which enables a more uniform loading of the filter belt 7 with the contaminant load.

Transverse to the grooves 55 and thus transversely to the feed direction 21 , the support body 11 contains a plurality of mutually parallel cylindrical bores 63 which are sealed at their ends by plugs 65 . Each of the bores 63 is connected to each groove 55 which it crosses through a bore 67 extending from the groove bottom and extending transversely to the support surface 15 . Averted from the support surface 15 go from each connecting bore 63 at least one, but preferably a plurality of spaced-apart connecting bores 69 , which in turn connect the connecting bores 63 with the collecting duct 17 extending in the housing 1 of the discharge duct 5 which removes the cleaned material. The passage bores 67 and the connecting bores 63 and 69 all have a circular cylinder cross section and are polished in order to keep the flow resistance of the cleaned plastic melt discharged by them as low as possible, so that the cleaning device can operate at the lowest possible melt pressure. It goes without saying that the grooves 55 and the collecting duct 17 as well as the ducts 3 and 5 can optionally have polished inner surfaces.

As mentioned above, the filter band 7 is made multilayered and has in the illustrated embodiment chen an endless, with the aid of Umlenkfüh stanchions 71 guided support layer 73 of a mechanically very stable even higher tensile and compressive forces can be exposed wire mesh or derglei and one on the supporting body 11 opposite side of the support layer 73 overlying filter layer 75 . The filter layer 75 also consists of a wire mesh, but simpler and therefore considerably more inexpensive design than the support layer 73 . The filter layer 75 is placed as "Einwegfil terband" coming from a supply roll 77 outside the housing 1 on the support layer 73 . The filter pore size of the filter layer 75 is smaller than the opening size of the support layer 73 .

After passing through the plastic cleaning device, the filter layer 75 loaded with the contamination load is separated from the support layer 73 in a cleaning station 79 by means of a preferably heated scraper blade 81 and disposed of together with the contamination deposited thereon. The support layer 73, on the other hand, is cleaned in the cleaning station 79 and again fed to the plastic cleaning device on its endless path. The cleaning station 79 comprises a heating device 83 , which heats the filter belt 7 before the separation of the filter layer 75 to the softening temperature of the contaminant load, as well as a blow-out device 85 , which blows off any remaining contaminant load on the support layer 73 . The cleaning station 79 can optionally comprise further scrapers or other cleaning devices, as is explained, for example, in WO 98/31527 or DE 199 16 539 A1.

In order to be able to easily replace the endless support layer 73 of the filter belt 7 , the housing 1 including the adjoining areas for the filter belt inlet 23 and the filter belt outlet 25 is along one of the two edge edges of the filter belt 7 with one from the outside to the edge of the filter belt 7 Approaching slot 84 ( Fig. 2) is provided, which is closed to the outside by a strip 86 . The bar 86 completely fills the slot 84 to avoid dead spaces for the plastic material within the housing, and is attached outside the slot. In the illustrated embodiment, the bar has a T-shaped cross section. For ease of assembly, the bar can be segmented in its longitudinal direction.

A variant of the cleaning device explained with reference to FIGS. 1 to 3 is described below. Components having the same effect are provided with the reference numbers from FIGS . 1 to 3 and for distinction with the letter a. To explain the structure and the effect, reference is made to the description of FIGS. 1 to 3. The components 9 , 15 to 19 , 59 , 61 and 65 shown in FIGS. 1 to 3 are not shown in FIGS. 4 and 5, but are present in a corresponding manner.

In contrast to the cleaning apparatus of Fig. 1 to 3, in which the support surface 15 passage of the support body 11 including the traversed by the filter belt 7 regions of the filter band inlet 23 and the Filterbandaus 25 lie substantially in a common plane, the supporting body 11 a of the Reinigungsvor shown Figs. 4 and 5 in the direction corresponding to a half-cylinder portion is curved and continues to the filter band inlet 23 a and 25 a toward the Filterbandauslass ent of long flat support surface areas 87 and 89 respectively continues. The filter band 7 a wraps around the curved support surface area of the support body 11 a over a wrap angle of approximately 180 °. The support body 11 corresponds to a far the supporting body of the cleaning device described in WO 98/31527, to which reference will be made in connection with FIGS. 4 and 5 for further explanation of the cleaning device.

The support surface of the support body 11 a is in turn hen with a plurality of grooves 55 a extending in the feed direction 21 a of the filter belt 7 a, which in this embodiment of the cleaning device can also be divided into two successive partial regions in the circumferential direction, in which the grooves 55 a better utilization of the filter bands can be offset against each other transversely to the feed direction 21 a, as previously explained with reference to FIG. 3 and is also described in WO 98/31527.

The support body 11 a contains transverse to the grooves 55 a, extending connecting holes 67 a, the circumference of the holes intersecting the grooves 55 a to form the connecting holes 67 a. It goes without saying that the connecting bores 63 a can also be arranged at a radial distance from the grooves and can be connected to the grooves by optionally polished connecting bores, as was explained above with reference to FIG. 2.

Each of the connecting bores 63 a is also connected via a plurality of radial, polished connecting bores 69 a running in the interior of the support body 11 a to a central guide channel 5 a formed as a collecting channel. This channel is also expediently designed and polished as a cylindrical bore. As shown in FIG. 4, the area of the supporting body 11 a provided with through holes 67 a and connecting bores 63 a, 69 a extends not only over the cylindrically curved part of its supporting surface, but also partly into the flat supporting surface regions 87 , 89 . In this way, a comparatively large usable filter area can be achieved despite the compact design.

The plastic material to be cleaned is distributed by means of a material distribution section 51 a tapering in the feed direction 21 a over the support surface area of the support body 11 a provided with through holes 67 a. The material distributing section 51 a is to be cleaned plastic material via a material supply section 53 a of the supply channel 3 a in the area of the counter to the feed direction 21 a located end of a fed of with through-hole 67 a provided support surface area of the support body 11 to the viscous friction in this way the along the filter belt 7 a flowing plastic melt to support the transport movement of the filter belt 7 a to take advantage of.

To seal the filter band inlet 23 a and the filter band outlet 25 a thermally insulated cooling devices 27 a, 29 a are again provided by thermal insulation 33 a from the heated housing 1 a, which cool the plastic melt to form solidified plastic sealing plugs. The sealing plug formed at the filter belt inlet 23 a is carried along during the transport movement of the filter belt 7 a due to the widening cross-sectional configuration of the filter belt inlet 23 a.

At the filter belt outlet 25 a is on the side facing the contamination load 19 a of the filter belt 7 a one across the entire width of the filter belt 7 a extending blocking bar 91 is provided, which related to the available for the filter belt 7 a and its contamination load 19 a outlet cross section on the cross section of the supply carriage with solidified Verunreini 19 a laden filter band 7 a narrowed. As the larger cross section area is already in the cooling zone 29 a, in the cooling zone 29 a resulting, solidified sealing plug, the advancing movement of the filter blocked belt 7 a. Fig. 4 shows in an exaggerated representation that the solidified area of the contamination load 19 a from the filter band outlet 25 a extends out.

The blocking device 35 a includes not only the blocking strip 91 still by an electric motor 93 a to the plane of the filter belt 7 a parallel, transversely a running axis of rotation 95 rotatably attached to the feed direction 21 exaggerated cylindrical milling cutter 97 with helically to parent cutting 99th In order to remove the blockage of the filter belt 7 a, the milling tool 97 mills the area of the solidified contamination load 19 a from the blocking bar 91 , whereby the filter belt 7 a including the possibly remaining portion of the contamination load 19 a leave the filter belt outlet 25 a can.

For a gradual feed of the filter belt 7 a, the milling tool 97 is operated intermittently. In order to prevent the cutting edges 99 of the milling tool 97 from sticking positively to the contamination load 19 a during the breaks in operation, which can make it difficult to restart the motor 93 if the motor is not adequately dimensioned, it is provided that the milling tool 97 during the break from operation Contamination load 19 a lifted off and thus can be brought out of engagement, as indicated in Fig. 4 at 97 '. The motor 93 can start in this way as long as the milling tool 97 is not yet in engagement with the contamination load 19 a.

The blocking bar 91 can optionally be omitted if the milling tool 97 remains in constant engagement with the contamination load 19 a, that is, it takes over the function of the blocking bar 91 .

It goes without saying that, in the embodiment according to FIG. 4, the blocking can take place instead of using a milling tool, also by means of a blocking stamp, as was explained with reference to FIG. 1. Alternatively, in the embodiment according to FIG. 1, a milling tool can also be used instead of the blocking stamp.

The filter belt 7a of the cleaning apparatus shown in FIG. 4 is formed as an endless belt and is guided on the one hand to the cylindrical portion of the support body 11a and other end on a rotatable guide wheel 71 a. The transport device 43 a provided to support the transport movement of the filter belt 7 a comprises a clamping jaw 45 a, which a hydraulic cylinder 49 a presses radially against the circumference of the deflection wheel 71 a. Details of such a transport device are explained in WO 98/31527, to which reference is made.

In the feed path of the filter belt 7 a, a cleaning station 79 a is arranged between the housing 1 a and the deflection wheel 71 a, which frees the filter belt 7 a, which is running and therefore reusable, from residues of impurities that may still adhere to it. In the cleaning station 79 a, the filter belt 7 a first passes through a scraping device 101 in which it is preheated by the heating device 83 a and is roughly freed from the contaminant load by means of the scraper 81 a. The scraping device 101 is followed by a fluidized bed cleaning device 103 , in which the filter belt is heated to a higher temperature than before by means of a further heating device 105 and is further cleaned by a particle stream, for example a sand stream. For the final cleaning follows a blow-out station 109 , in which the filter belt 7 a is blown with a hot air stream supplied via the nozzle 85 a. Individual units of the cleaning station 79 a are explained in WO 98/31527. Reference is made to the explanations.

In the embodiment of Fig. 4, the filter belt 7 is designed as a single-layer metal mesh band. Instead of such an endless filter band, however, a multi-layer version of a filter band with an endless, coarsely meshed support layer and a finer meshed filter layer intended for single use can also be used, as was explained with reference to FIGS. 1 to 3. It is understood that in the embodiment of FIGS. 1 to 3 a single-layer filter band can also be used. Correspondingly, the transport device shown in FIG. 1 can also be provided in a cleaning device according to FIG. 4, or the transport device of FIG. 4 can be used in the variant of FIG. 1.

Claims (25)

1. Device for cleaning thermoplastic material, in particular plastic material, from solid contaminants, comprising a housing ( 1 ) with a feed channel ( 3 ) for the material to be cleaned and a discharge channel ( 5 ) for the cleaned material,
a the flow path of the material in the housing ( 1 ) between the feed channel ( 3 ) and the discharge channel ( 5 ) seals penetrating, in the longitudinal direction displaceable filter band ( 7 ) for separating the solid impurities,
one on the chute (5) facing side of the filter band (7) in the flow path arranged supporting body (11) having a plurality of adjacently disposed passageways (13) for the passage of the purified material to the discharge channel (5),
the housing ( 1 ) in the region of its filter band inlet ( 23 ) and in the region of its filter band outlet ( 25 ) with respect to the filter band ( 7 ) sealing means ( 27 , 29 ), and
Means ( 43 ) for the gradual or continuous advance of the filter belt ( 7 ),
characterized by
that the sealing means ( 29 ) of the filter belt outlet ( 25 ) cool the contaminant containing a portion of thermoplastic material ( 19 ) of the filter belt ( 7 ) at least approximately until it solidifies
and that at the Filterbandauslass (25) the cross-sectional size of the Filterbandauslasses (25) and the cross-sectional size of the loaded with the solidified impurity freight (19) filter band (7) for blocking or releasing the advancing movement of the filter band (7) relative to each other changing controllable blocking device (35 ) is provided. 2. Device according to claim 1, characterized in that the blocking device ( 35 ) one of a controllable actuator ( 39 ) transversely to the feed direction ( 21 ) of the filter belt ( 7 ) on its solidified contamination load ( 19 ) to or from this movable baren Stamp ( 37 ). 3. Device according to claim 2, characterized in that the stamp ( 37 ) is arranged on the side of the contamination load ( 19 ) opposite the filter belt ( 7 ). 4. The device according to claim 3, characterized in that the stamp ( 37 ) on its side facing the contamination load ( 19 ) has clamping projections ( 41 ). 5. Device according to one of claims 2 to 4, characterized in that the actuator ( 39 ) is formed as a hydraulic pressure cylinder. 6. The device according to claim 1, characterized in that the filter belt outlet ( 25 a) has a contamination ( 19 a) in the feed direction ( 21 a) of the filter belt ( 7 a) engaging behind the constriction ( 91 )
and that the blocking device ( 35 a) comprises a solidified contamination load ( 19 a) of the filter belt ( 7 a) at least apart from a cross-section that removes, in particular motor-driven, tool ( 97 ) that can move past the constriction ( 91 ). 7. The device according to claim 6, characterized in that the tool ( 97 ) is designed as a milling tool. 8. The device according to claim 7, characterized in that the axis of rotation ( 95 ) of the milling tool ( 97 ) extends transversely to the feed direction ( 21 a) of the filter belt ( 7 a) and the contamination load ( 19 a) parallel to the plane of the filter belt ( 7 a ) removes. 9. Device according to one of claims 6 to 8, characterized in that the tool ( 97 ) for the starting process of its drive ( 93 ) is substantially completely out of engagement with the Ver contamination load ( 19 a) can be brought. 10. Device according to one of claims 6 to 9, characterized in that the narrowing of the filter band outlet ( 25 a) is formed by the tool ( 97 ) itself. 11. The device according to one of claims 1 to 10 or the Oberbe handle of claim 1, characterized in that the feed channel ( 3 ) for the material to be cleaned in the feed direction ( 21 ) of the filter belt ( 7 ) substantially over the entire with passage channels ( 13 ) provided region of a support surface ( 15 ) of the support body ( 11 ) supporting the filter belt ( 7 ) and a material distribution section ( 51 ) extending into the housing ( 1 ) leading into the material distribution section ( 51 ) material supply section ( 53) and that the Materialzuleitungsab section (53) opposite to the feed direction (21) of the filter band (7) against the related to the feed direction (21) mid provided with passage channels (13) portion of the support surface (15) of the support body (11) offset opens into the material distribution section ( 51 ). 12. The apparatus according to claim 11, characterized in that the material feed section ( 53 ) in the region of the opposite to the feed direction ( 21 ) of the filter belt ( 7 ) located end of the material distribution section ( 51 ) opens into this. 13. The apparatus of claim 11 or 12, characterized in that the material distribution section ( 51 ) tapers in the feed direction ( 21 ) of the filter belt ( 7 ), in particular tapers continuously. 14. Device according to one of claims 1 to 12 or the Oberbe handle of claim 1, characterized in that the support body ( 11 ) at least in the region of its ver with passage channels ( 13 ) seen, the filter belt ( 7 ) supporting support surface ( 15 ) Has a plurality of grooves ( 55 ) which extend parallel to one another and in the feed direction ( 21 ) of the filter belt ( 7 ) and are open towards the support surface ( 15 ) and from which the passage channels ( 13 ) extend,
that the support body ( 11 ) contains a plurality of cylindrical first connecting bores ( 63 ) which extend transversely to the grooves ( 55 ) and which are connected to the crossed grooves ( 55 ) via connecting holes ( 67 ) to form the through-channels ( 13 ),
and that each of the first communication bores (63) through a little least one, preferably a plurality of second are connected in the supporting body (11) transverse to the first connecting bore (63) extending, cylindrical connecting holes (69) with a collecting channel (17), and
that at least the first and second connecting bores ( 63 , 69 ) have polished bore surfaces. 15. The apparatus according to claim 14, characterized in that the first connecting bores ( 63 a) cut the grooves ( 55 a) to form the connecting holes ( 67 a). 16. The apparatus according to claim 14, characterized in that the first connecting bores ( 63 ) are connected to the grooves ( 55 ) via drilled, in particular polished, drilled holes ( 67 ) transverse to the support surface ( 15 ). 17. Device according to one of claims 14 to 16, characterized in that the support body ( 11 ) is detachably connected to the housing ( 11 ) and the collecting channel ( 17 ) in the housing ( 1 ) is formed. 18. Device according to one of claims 14 to 17, characterized in that the grooves ( 55 ) and / and the collecting channel ( 17 ) have po liert wall surfaces. 19. Device according to one of claims 14 to 18, characterized in that the measures provided in a first part region (59) of the support surface (15) grooves (55) terminate within the support surface (15) and in an in feed direction (21) the following second section ( 61 ) of the support surface ( 15 ) provided grooves ( 55 ) begin within half of the support surface ( 15 )
and that the grooves ( 55 ) of the second section ( 61 ) are offset relative to the grooves ( 55 ) of the first section ( 59 ) transversely to the direction of advance ( 21 ) of the filter belt ( 7 ). 20. Device according to one of claims 1 to 19, characterized in that the passage channels ( 13 ; 13 a) provided Be rich one of the filter belt ( 7 ; 7 a) supporting support surface ( 15 ; 15 a) of the support body ( 11 ; 11 a) is flat or convexly curved in the feed direction. 21. Device according to one of claims 1 to 20, characterized in that the filter belt ( 7 ) is constructed in several layers and an endless support layer ( 73 ) adjacent to the support body ( 11 ) and on the side facing away from the support body ( 11 ) having support layer (73) overlying filter layer (75), wherein the filter layer (75) is fine-meshed than the support layer (73). 22. An apparatus according to claim 21, characterized in that the filter layer rests (75) loosely on the support layer (73) and from a supply pocket (77) before reaching the filter band inlet (23) can be placed coming to the endlessly circulating supporting layer (73). 23. The device according to claim 22, characterized in that the endless support layer ( 73 ) in the feed direction ( 21 ) after the filter band outlet ( 25 ) a layer separating device ( 81 ) separating the filter layer ( 75 ) and subsequently only the support layer ( 73 ) cleaning device ( 79 ) which frees of contamination load runs through. 24. The device according to claim 23, characterized in that the layer separating device ( 81 ) has at least one in particular heatable doctor blade. 25. Device according to one of claims 1 to 24, characterized in that the housing (1) (7) to the filter belt (7) reaching, is running along a peripheral edge of the filter bands one over the entire inside of the casing (1) Section of the filter belt ( 7 ) extending slot ( 24 ) closed by a one-part or multi-part, removable strip ( 86 ).