EP0952912A1

EP0952912A1 - Device for cleaning viscous material

Info

Publication number: EP0952912A1
Application number: EP98907942A
Authority: EP
Inventors: Josef Gail
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-01-14
Filing date: 1998-01-13
Publication date: 1999-11-03
Also published as: US6375013B1; WO1998031527A1; DE19704621A1

Abstract

The invention relates to a cleaning device for removing solid impurities from viscous material, in particular molten plastics material, comprising, inside a housing (1), a filter band (5) for separating out solid impurities which can be moved in its longitudinal direction. The filter band (5) is wrapped around a curved supporting area (7) of a fixed supporting member (3) at an angle of wrap of preferably approximately 180°, and is guided on both sides of the curved supporting area (7) in level supporting areas (15, 17) which lie tangentially and flush against the curved supporting area (7). To reduce the kinetic resistance of the filter band (5), the curved supporting area (7) and at least partly the level supporting areas (15, 17) are provided with grooves (25) extending in the direction of transport of the filter band (5). The plastics material to be cleaned is supplied via a feeding chamber (23) surrounding the supporting area, and, after it has been cleaned, is removed via connecting channels (27, 35) extending from the grooves (25). On the outlet side of the cleaning device the filter band (5) passes through a cleaning station (67). In this way the filter band can be reused. The proposed cleaning device is compact and allows for relatively large effective filtering surfaces.

Description

Device for cleaning viscous material

description

The invention relates to a device for cleaning viscous material, in particular a plastic melt from solid contaminants.

From EP 615 829 AI a device is known by means of which solid-state contaminants, for example metal particles or the like, can be separated from a viscous melt from thermoplastic material. The known device has a tubular cylindrical screen body with a multitude of narrow holes in its jacket. The sieve body is seated in a support tube which, in order to discharge the cleaned material, contains a plurality of axial channels distributed in the circumferential direction, which in turn merge on the inner jacket of the support tube into circumferential grooves open to the holes in the sieve body. The circumferential grooves can either be molded into the sieve body or the support tube. For cleaning, the plastic melt is pressed into the cavity of the filter body by means of an extruder and is removed in a cleaned manner from the outside of the filter body via the channels of the support tube. A rotating scraper shaft arranged in the filter body 5 with the same axis scrapes off the filtered impurities from its inner casing. In order to prevent the filter holes of the filter body from becoming clogged, the hole diameter must not be chosen too small, which, however, has an adverse effect on the purity 0 of the cleaned plastic material.

From DE 35 35 491 Cl and CH 469 547 it is known to press the plastic melt to be cleaned by means of an extruder through a close-meshed filter belt made of wire mesh, which is provided on the outlet side of the cleaned plastic melt with a large number of relatively large passage openings Supporting body supports. The sieve belt holds back the solid contaminants to be separated and is moved along the supporting surface of the supporting body by means of a hydraulic transport device or due to hydrostatic forces of the melt in order to transport the solid contaminants out of the flow path of the plastic material. In the known device, the support surface is flat and the sieve belt is also transported along a plane. Viewed overall, however, the surface area of the screen belt that penetrates the flow path of the plastic material is comparatively small, which means that the cleaning performance of the device does not meet increased requirements.

The melted plastic material to be cleaned is highly viscous and therefore requires a high supply pressure, which the narrow-meshed filter belt, which is preferably designed as a metal mesh, cannot withstand itself in larger areas. The area ratio of support surface sections on which the filter belt can be supported on the one hand and opening cross sections of the through holes opening into the support surface on the other hand must be selected in accordance with the given strength of the filter belt.

Conventional support bodies are usually provided with a multiplicity of bores arranged in a grid which penetrate the support plate, which is often plate-shaped. Support bodies of this type, however, do not meet increased filter performance requirements, since bores that are too narrow tend to clog and holes that are too wide cannot adequately support the filter belt. The size of the holes also affects the mechanical strength of the support body and limits its load-bearing area to relatively small values if an excessively voluminous and therefore heavy construction of the cleaning device is to be avoided. 5

From JP 61-175 016A (Patent Abstracts of Japan M-548, December 24, 1986, Vol. 10 / No. 385) and US Pat. No. 4,080,297 it is known knows to guide the filter band over a partial circumference of a circular cylindrical, hollow support drum which is provided in its circumferential wall with a large number of axial slots. The plastic melt to be cleaned is fed from the radially outside to the filter belt and removed in a cleaned form from the interior of the support drum. The wrap angle of the filter band can be 180 ° and more, which enables a comparatively large effective filter area. Similar filter devices are described in U.S. Patents 3,645,399 and 3,856,674. In the case of cleaning devices with a rotating support drum, it is not only necessary to ensure that the inlet and outlet channels of the filter band are sealed relative to the housing in order to ensure the high supply pressure of the plastic melt, but also that the support drum is sealed in the area of these channels. Wedge-shaped cutting edges are formed on the housing in the area of the inlet side and the outlet side of the filter band, which reach between the filter band and the peripheral surface of the support drum at the inlet or outlet point. Since such cutting edges must have a certain minimum thickness because of the high prevailing pressures, the filter band is deformed particularly when it passes from the support drum to the cutting edge on the outlet side and is exposed to the risk of damage.

Compared to rotating support drums, the filter belt in stationary support bodies is exposed to a very high resistance to movement, which prevents the filter belt from being transported even with a comparatively small effective filter surface, as long as it is under the high pressure of the plastic melt. The high pressure of the plastic melt bulges the filter belt into the large number of through openings of the stationary support body, and accordingly the filter belt hooks onto the support body. In order to be able to transport the filter belt anyway, the pressure of the plastic melt on the feed side for the transport of the filter belt is reduced as far as possible in conventional cleaning devices. So it is known from DE 35 35 491 Cl, the volume to enlarge the feed chamber for the pressure reduction. It is known from EP 0 275 462 A2 to alternately feed the plastic melt to be cleaned via a three-way switch valve to two cleaning devices. The cleaning device that is not working in the cleaning operation is therefore depressurized, so that its filter belt can be transported. Despite the reduction in the supply pressure of the plastic melt, the resistance to movement of the filter belt is still relatively high, so that for this reason the usable filter area must be kept comparatively small when using a stationary support body.

It is an object of the invention to provide a device for cleaning viscous material, in particular a plastic melt of solid impurities, which is compact on the one hand and on the other hand allows the material to be cleaned with a high degree of purity and comparatively high cleaning performance.

The device according to the invention for cleaning viscous material, in particular a plastic melt from solid-state contaminants, comprises: a housing with a feed channel for the material to be cleaned and a discharge channel for the cleaned material, 5 a sealingly penetrating the flow path of the material in the housing between the feed channel and the discharge channel, longitudinally displaceable filter belt for separating the solid contaminants, a support body fixedly arranged in the flow path on the side of the filter belt facing the discharge duct with a support surface supporting the filter belt, the contour of which in a curved, the filter belt over a wrap angle of more than 90 ° Deflecting support surface area essentially follows the shape of a cylinder surface, in particular a circular cylinder surface, and in both sides of the curved support surface area tangentially and flush with the curved surface support surfaces rich adjoining support surface areas is essentially flat, with a plurality of grooves that extend parallel to one another and next to one another in the direction of displacement of the filter belt and are open towards the support surface at least in the curved support surface area and with a plurality of passage channels that start from the grooves for the passage of the cleaned material to the discharge channel, wherein the feed channel comprises a feed chamber covering at least the grooved area, a transport device for the continuous or gradual feed of the filter belt.

Due to the curved construction of the support body, the cleaning device is very compact, even if the usable surface area of the filter belt is comparatively large. Such a support body can also better withstand the high feed pressure of the plastic melt, which can reach 300 bar or more. In addition, the dead volume of the plastic melt in such a construction is comparatively low, which facilitates the thermal control of the cleaning process.

Since the flat support surface areas connect tangentially and flush, i.e. continuously and without a jump offset to the curved support surface area, the filter belt is not mechanically deformed, unlike in conventional cleaning devices with a rotating support drum, when it approaches or runs down the curved support surface area, which is particularly advantageous is when the filter belt is to be cleaned and reused. Since at least the curved support surface area is provided with grooves running in the transport direction of the filter belt, the resistance to movement of the filter belt can be kept relatively low. Even if the filter belt should bulge into the grooves due to the pressure of the plastic melt, it can still run along the grooves be moved after the passage channels open into the grooves and not immediately in the support surface.

In a preferred embodiment, the planar support surface areas are also provided, at least in a partial area adjacent to the curved support surface area, with a plurality of grooves which are parallel to one another and extend in the direction of displacement of the filter belt and are open towards the support surface, of which passage channels for the passage of the device - Go out of the necessary material to the discharge channel. Such a construction enables extraordinarily large effective filter areas, in particular if the wrap angle with which the filter band wraps around the curved support surface area is approximately 180 ° or even more.

A stable construction, which nevertheless sufficiently supports the filter band even with a large effective filter area, is achieved if the support body for the formation of the passage channels has a plurality extending transversely to the grooves and the cross-sectional contour of a plurality of grooves for the formation of passage holes intersecting connecting channels. Such a support body can be produced with little effort, in particular also as a solid, integral block of material. In the case of such a support body, the connecting channels can also be connected to a collecting channel of the discharge channel opening essentially centrally to them. As a result, not only can the dead volume of plastic melt within the housing be reduced, but this goal can also be achieved with little production outlay while ensuring the mechanical strength of the support body. It could be considered to let the connecting channels open into a slot-like, radial extension of the discharge channel on the side of the support body. From the point of view of the smallest possible dead volume of plastic melt, however, it is also expedient here that the, within the support body, preferably running parallel to the cylinder-generating end of the curved support surface area, to connect the most channel sections of the connecting channels to the collecting channel via respectively assigned, radially running second channel sections.

During the cleaning process, the filter belt is loaded with solid contaminants in the area of the grooves. Although it is sensible from the point of view of a movement resistance that is as low as possible to make the grooves free of jumps, in a preferred embodiment it is nevertheless provided that the grooves provided in a first partial region of the support surface end within the support surface and in one in the direction of displacement the subsequent second sub-area of the support surface begin within the support surface, the grooves of the second sub-area being offset relative to the grooves of the first sub-area to a gap. With such a design of the grooves, the entire filter belt area can be used for cleaning, which considerably increases the service life of the filter belt.

Between the beginning of the grooves of the second portion of the support surface, i.e. on the ribs remaining between these grooves, bevels on the support body can be provided to reduce the resistance to movement of the filter belt.

Seen in the direction of displacement of the filter belt, the length of the first and second sub-areas of the support surface is selected such that the filter belt is loaded with impurities as evenly as possible. The ends of the grooves of the first partial region of the support surface and the beginnings of the grooves of the second partial region, as viewed in the direction of displacement of the filter belt, are expediently located approximately in the center of the support surface.

The feed channel can open into the housing coaxially with the discharge channel. In this way the installation of the cleaning direction in a more complex plastics processing plant or the like. A structurally particularly simple embodiment, on the other hand, provides that the feed channel opens into the feed chamber with a channel section of the housing running approximately radially to the support surface. In this way, the dead volume of material to be cleaned can be reduced further within the housing and still ensure a uniform coating of the filter belt. The channel section preferably opens into the feed chamber as seen approximately in the circumferential direction of the support surface.

A particularly compact configuration of the cleaning device is achieved when the filter belt, as already mentioned, wraps around the support body by at least 180 ° and with at least approximately parallel, flat band sections running parallel to one another within the housing in an essentially flat band feed chamber towards the support body is guided and is guided away from the support body in a substantially flat tape discharge chamber. The tape feed chamber and the tape discharge chamber are parallel to each other, which not least facilitates the temperature control of the housing.

When cleaning thermoplastic material, the material in the area of the support body is kept at the melting temperature. B. at a temperature of 180 ° C to 330 ° C depending on the material, but also at a higher or lower temperature, by means of a temperature control. In the area of the band feed chamber and / or the band discharge chamber, on the other hand, the housing is cooled in order to at least seal the exit point of the filter band with solidifying material. In order to achieve this goal in a small installation space of the housing, the tape feed chamber and / or the tape discharge chamber is subdivided into a temperature zone close to the support body and a cooling zone remote from the support body by means of thermal insulation running transversely to the plane of the belt sections of the filter belt guided therein. In a preferred embodiment it is provided that the band feed chamber and / or the band discharge chamber widens at least in a partial area in the transport direction of the filter band transversely to the plane of the filter band. The widening of the belt discharge chamber, which is expediently located in the cooling zone, facilitates the removal of the filter belt loaded with impurities, while the widening of the belt feed chamber, which narrows again near the support drum, facilitates the temperature control of the material to be cleaned.

The tape feed chamber, but in particular the tape discharge chamber, can be adequately sealed by means of a "plug" made of solidified plastic melt, as was explained above. However, it has been shown that heat regulation is problematic, in particular on the side of the belt outlet, since there the filter belt is loaded with contaminants which have a strong influence on the solidification behavior of the plastic melt. In particular, the period of time required to change the state of aggregate of the plastic melt can increase sharply, which adversely affects the cleaning performance of the device. Disadvantages of this type can be avoided if, as is provided in a preferred embodiment, at least on the side of the band discharge chamber, a movably guided transversely to the plane of the filter band, removed from a drive device between a sealing position sealingly resting on the filter band and one from the filter band located release position adjustable sealing strip is provided. In order to be able to lead the sealing strip, which is movable relative to the housing, in a sealed manner despite the high pressure of the plastic melt, it is provided that the sealing strip, with its side surface facing away from the flow path of the material to be cleaned, extends across the entire width of the filter strip at one side Sealing surface of the housing is supported flat. With such a construction, the pressure of the molten plastic also generates the contact pressure of the surfaces that are assigned to one another and are preferably ground. The sealing bar extends transversely to the filter band beyond its longitudinal edges and is also sealed in this area via its side faces to the sealing surface of the housing. With the sealing strip resting on the filter band, it can thus completely encompass the 5 filter band and provide an all-round seal. The sealing strip is expediently made of metal and is provided on its side facing the filter band with an elongated seal made of elastomers or other elastic material. Although such a seal, in particular of the tape discharge chamber, is particularly suitable for the cleaning device explained above, this sealing construction can also be used advantageously for other cleaning devices of the type in question. 5

The drive device which moves the sealing strip between its two positions is expediently designed as a hydraulic cylinder or the like. Such or another drive device is expediently located outside the flow path of the plastic material, i.e. arranged in a pressure-free area. The actuation forces are preferably transmitted to the sealing strip via at least one cylindrical dowel pin, which is movably guided in a fitting bore in the housing. The dowel pin 5 is expediently a loose pin in order to avoid constraining forces. Preferably, at least two dowel pins are arranged at a distance from one another on both sides of the sealing strip, the fitting openings of which extend in the direction of movement of the sealing strip, the drive device for actuating the dowel pins driving oblique thrust surface elements.

The transport of the filter belt can be brought about by hydrostatic pressure differences in the flow path of the plastic melt. Especially in embodiments in which the pressure 5 of the plastic melt is reduced during the transport process in order to reduce the resistance to movement of the filter belt, a transport drive driving the filter belt is preferred. direction provided. The transport device can be designed as a pair of pressure rollers. However, it is preferably a hydraulically displaceable and hydraulically operable clamping pliers, which grips the filter belt during clamping. The clamping pliers can cooperate with a deflection wheel deflecting the filter band and comprise a clamping jaw pressing against the circumference of the deflection wheel. However, the clamping pliers can also be designed as a slide ιo that can be moved hydraulically on a linear guide along the filter belt.

Conventional cleaning devices of the type in question feed the filter belt from a supply roll. Depending on the degree of contamination of the material to be cleaned and the degree of cleaning of the cleaned material, the consumption of filter belt can be comparatively large. In order to reduce the consumption of the filter belt, it is provided in a preferred embodiment that the filter belt is designed as an endless filter belt and in its feed direction relative to the support

20 bodies moved through a cleaning station. The cleaning that takes place continuously or step by step in accordance with the feed of the filter belt not only saves filter belt expenditure, but also enables a reduction in the material pressure on the feed side of the material to be cleaned.

25 Conventionally, high material pressures resulting from contamination of the filter belt due to contamination have also been permitted for economical use of the filter belt. If, on the other hand, as suggested, the filter belt is cleaned at the same time during the material cleaning process,

30, the degree of clogging and thus the material pressure to be applied can be reduced by a suitable choice of the transport speed of the filter belt without assembly times for the belt change or increased filter belt consumption.

35

The above-described aspect of an endless filter belt with an associated cleaning station is not only possible use in cleaning devices of the type explained above, but is also of independent inventive importance in conventional cleaning devices.

In a preferred embodiment, the filter belt is guided in an endlessly revolving manner on the curved support surface section of the support body and at least one rotatably mounted deflection wheel. The deflection wheel can be designed as a drive deflection wheel driven by the transport device. The deflection wheel drive can form the only drive for the filter belt, if necessary by driving all the existing deflection wheels.

The idea of cleaning the filter belt loaded with material contaminants directly after the material cleaning device in turn in a cleaning station in order to be able to reuse it can be used not only with endless filter belts, but also with devices in which the filter belt is operated by one Supply wrap is fed. The contaminated filter tape running out of the material cleaning device becomes so smooth again through the cleaning that it can be wound up and used again. In a preferred embodiment it is provided that the support body is arranged in the feed path of the filter belt between a supply winding arrangement dispensing the filter belt and a winding arrangement receiving the filter band, and that a cleaning station is arranged in the feed path offset relative to the support body between the support body and the winding arrangement passes through the filter belt. As in the case of the material cleaning device with an endless filter belt, the cleaning station can not only be used with material cleaning devices of the type explained above, but is also of independent inventive importance in conventional cleaning devices. In both variants explained above, the cleaning station is preferably constructed in several stages in order to achieve a cleaning effect that is gradually adapted to the cleaning state. In a preferred embodiment, the cleaning station in the feed direction of the filter belt successively comprises a scraping device and subsequently at least one cleaning device. In the case of thermoplastic material to be cleaned, it has proven to be advantageous in this context if the scraping device is assigned heating means preheating the filter belt and the at least one subsequent cleaning device the heating means increasing the temperature above the preheating level. The cleaning device following the scraping device can be a fluidized bed cleaning device in which the filter belt is exposed to a particle stream, for example sand. The fluidized bed cleaning device expediently operates at a temperature which is considerably above the melting temperature of thermoplastic material, for example at least 400 ° C., while the scraping device, in order to facilitate the scraping process, operates in the range of the softening temperature of the material, for example of the order of magnitude of 200 ° C. However, the temperatures depend on the material.

For the final cleaning of the filter belt, one of the cleaning devices can be designed as a blow-out device which blows the filter belt with hot air, for example.

In order to be able to insert the filter band into the housing, the housing must generally be dismantled. In a preferred embodiment, which makes it much easier to insert or change the filter band, it is provided that the housing is designed to be divisible and comprises a possibly multi-part, removable wall section which covers the edge of the filter band over the entire length of the filter band running inside the housing. By removing this lid-like wall section, the edge area of the filter band is over its entire length running inside the housing is exposed, so that the filter band can be removed from the housing or inserted into it transversely to its direction of advance. The feed channel and the discharge channel expediently open into the remainder of the housing, so that these channel connections do not have to be released for changing the filter belt.

Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. Here shows:

Fig. 1 is a sectional view of a device for cleaning a plastic melt of solid contaminants, seen along a line I-I in Fig. 2;

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

3 shows a section through a detail of the device, seen along a line III-III in FIG. 2;

4 shows a sectional view similar to FIG. 1 through a variant of the device; FIG. 5 shows a sectional view of a sealing device as can be used in the device according to FIG. 4, seen along a line V-V in FIG. 6;

Fig. 6 is a sectional view of the sealing device, seen along a line VI-VI in Fig. 5; FIG. 7 shows a plan view of a transport device as can be used in the device according to FIG. 4;

Fig. 8 is a sectional view of the transport device, seen along a line VIII-VIII in Fig. 7 and Fig. 9 shows another variant of a device for cleaning a plastic melt from solid contaminants.

Especially for cleaning viscous material, especially a plastic melt from solid contamination

Metal waste and the like certain device comprises a housing 1, which contains a support body 3 in a chamber holds. An endless filter belt 5 consisting of a very close-meshed, possibly multi-layer metal fabric wraps around a curved peripheral jacket area or support surface area 7 of the support body 3 over a wrap angle of approximately 180 ° along a transport path, which is explained in more detail below, in which the filter belt 5 in the direction of an arrow 9 inserted into the housing 1 and discharged from the housing 1 after rotating the supporting body with the solid contaminants. For the transport, the filter belt 3 is guided around a deflection wheel 11 which interacts with a hydraulic transport device 15 which will be explained below. The transport device 13 transports the filter belt 3 step by step.

The support body 3 is arranged fixed in the chamber of the housing 1 and deflects the filter belt 5 by 180 °. The filter belt 5 runs along flat support surface areas 15, 17 onto the curved support surface area 7 or from it again. The flat supporting surface regions 15, 17 merge tangentially and flush into the curved supporting surface region 7.

The plastic material to be cleaned enters via a feed channel 21 provided with a connecting flange 19 into a feed chamber 23 of the housing 1 which follows the support surface contour of the support body 3 along the curved support surface region 7 and the flat support surface regions 15, 17. The feed channel 21 is arranged at a central point of the housing 1 both in the circumferential direction of the feed chamber 23 and in the axial direction of the feed chamber 23 and penetrates the housing wall radially to the center of the circular-cylindrical curved support wall region 7. The support wall regions 7, 15 and 17 are provided with a large number Grooves 25 extending parallel next to one another in the transport direction of the filter belt 5 are provided, which extend in the transport direction of the filter belt 5 both over the curved support surface region 7 and also over partial regions of the flat support surface that directly adjoin the region 7. che areas 15, 17 extend. The grooves 25 thus extend in planes running perpendicular to the cylinder-generating ends of the curved support surface region 7. Transversely to the grooves 25, the support body 3 contains a multiplicity of, for example cylindrical, channels 27 which are distributed along the grooves 5 and extend parallel to one another and which cut the grooves 25 to form passage openings 29, as best shown in FIG. 3. The channels 27 expand continuously or, as here, step-like in the flow direction to a discharge channel 33 formed by a connection ιo flange 31 of the housing 1. The discharge channel 33 is connected to the individual channels 27 via radial connection channels 35 formed in an end face of the support body 3. Although the connection of the discharge channel 35 to the channels 27 would also be possible by means of a common radial gap, the dead volume of plastic melt in the housing 1 is reduced by the connection via individual radial connecting channels 35, which facilitates the heat regulation of the device. To reduce their heat capacity, the support

₂ o body 3 provided with an inner chamber 37.

The filter belt 5 passes on its transport path within the housing 1 through an essentially flat belt feed chamber 39, to which the flat support surface extends in a straight line.

25 rich of the support body 3 connects. On the outlet side, an essentially flat tape discharge chamber 41 adjoins the flat support region 17 of the support drum 3 in a likewise linear extension. At least in the area of the support body 3, but preferably in its entire path inside

30 half of the housing 1, the filter band 5 is guided through edge flanges 43 (FIG. 2) at its edges.

The plastic material must be kept at the softening or melting temperature during the cleaning process. For this purpose 35, heat medium channels 45 are located in the housing 1 both in the vicinity of the support body 3 and in the adjoining areas of the tape feed chamber 39 and the tape discharge chamber 43 for a fluid used for temperature control, which can be air or a liquid, such as water. The temperature control fluid is fed in and, if necessary, discharged via manifolds indicated at 47 (FIG. 2) or the like. A temperature control, not shown, keeps the housing 1 and thus the plastic melt at a suitable temperature of, for example, 180 ° C. to 330 ° C., preferably 200 ° C. to 220 ° C.

In order to prevent the plastic melt from escaping via the tape feed chamber 39 and the tape discharge chamber 41, a cooling zone 49 connects in the housing 1 on the input side of the tape feed chamber 39 and on the output side of the tape discharge chamber 41 running parallel thereto, in which the housing 1 is separated from the channels 45 Contains channels 51 for a cooling fluid, preferably because of the greater heat capacity, a cooling liquid. Inlet and outlet devices for the cooling fluid are indicated at 53 in FIG. A separate temperature control device is assigned to the cooling zone 49, which ensures that the plastic material that is forced out of the chambers 39, 41 solidifies and thus seals these chambers from the outside. In order to be able to keep the cooling zone 49 at a lower temperature level, this area of the housing 1 connects to the part of the housing 1 containing the support body 3 via a thermal insulation layer 55. The tape feed chamber 39 widens slightly from the cooling zone to the area of the support surfaces in order to facilitate the temperature control of plastic materials that may have penetrated into the tape feed chamber 39. In a corresponding manner, the band discharge chamber 41 widens outward in the region of the cooling zone 49 in order to facilitate the removal of the filter band 5 loaded with impurities.

The filter belt 5 is intermittently advanced by the transport device 13 in the direction of arrow 9 as soon as the pressure detected by a pressure sensor, not shown increases in the feed channel when the filter belt 5 is excessively loaded with impurities. The transport device 13 comprises a clamping jaw 57, which a hydraulic cylinder 59 presses radially against the filter belt 5 guided on the circumference of the deflection wheel 11. For this purpose, a support lever 61 is mounted coaxially with the deflection wheel 11, at the free end of which an articulated lever 65 is articulated at 63, which is articulated with its one arm to the clamping jaws 57 and with its other arm to the piston rod of the hydraulic cylinder 59. One arm of the angle lifter 65 runs essentially in the circumferential direction of the deflection wheel, specifically in the direction of advance, while the other arm extends in the extension of the support lever 61. In this way, the hydraulic cylinder 59 generates not only a force component that pushes the filter band 5 on the clamping jaw 57, but also a force component that presses the clamping jaw 57 against the filter band 5.

Although the cleaning device explained above has a very compact design, large usable filter areas of the order of magnitude of 0.1 m ² and more can be implemented without problems. Since the passage openings 29 formed between the grooves 25 and the channels 27 lie at the bottom of the grooves 25, the resistance to movement which the filter belt 5 opposes to its transport movement is relatively small despite the comparatively large usable filter area. In particular, if the supply channel 21 is relieved of pressure during the filter belt transport phase, the filter belt 5 can also be moved with simple transport devices.

In the cleaning operation, the filter belt is primarily loaded with impurities in the area of the grooves 25. The strip-shaped support surface regions remaining between the grooves 25 are used only insufficiently in this way. In order to remedy this, the grooves beginning in the flat support surface region 15 on the feed end end within the curved support surface region 7, as indicated at 57 in FIG. 3 with an inclined surface increasing in the transport direction 9 while, on the other hand, the grooves 25 extending towards the outlet-side, flat support surface region 17 begin within the curved support surface region 7, as is indicated at 59. The output-side grooves 25 are set transversely to their longitudinal direction on a gap against the input-side grooves, with which a complete loading of the filter belt 5 with impurities and thus a better utilization of the filter belt 5 can be achieved.

In order to be able to change the filter band without problems, the housing has a side wall part 61 (FIG. 2) which is free of material feed openings and which is held detachably in the manner of a cover on the remaining housing by means of screw connections or the like (not shown). The dividing surface course indicated at 63 lies at a point at which the edge of the filter belt 5 is accessible over the entire length of the filter belt region running within the housing 1 when the wall part 61 is removed. After the wall part 61 has been removed, the filter band 5 can be pulled out of the housing 1 transversely to its transport or longitudinal direction or inserted into the housing 1.

Alternatively, the wall 61 can also form the feed channel, as indicated at 21 '. The supply channel 21 'is then in turn associated with connecting channels 65 which connect it to the supply chamber 23. The feed channel 21 'and the drain channel 33 are expediently arranged coaxially, which in certain applications can facilitate the installation of the cleaning device in a more complex system.

In order to be able to use the endless filter belt even in continuous operation, ie with more than one circulation, the filter belt 5, which is coming out of the cleaning device and is loaded with contaminants, passes through a multi-stage cleaning station 67 in this case, before it runs onto the deflection roller 11 is freed of the deposits in order to then be fed to the cleaning device again. In the cleaning station 67 the filter belt 5 first passes through a scraping device 69, in which the filter belt 5 is preheated by means of a heating device 71 and is roughly freed of adhering impurities by means of at least one scraper 73 resting on the filter belt 5. The scraper device 69 is followed in the feed path of the filter belt 5 by a fluidized bed cleaning device 75, in which the filter belt 5 is heated to a temperature above the preheating temperature of the heating device 71 by means of a heating device 77 and further cleaned by a particle stream 79, in particular a sand stream becomes. While the preheating temperature depends on the material to be cleaned, for example between 160 ° C and 350 ° C, on average at about 200 ° C to 220 ° C, the filter belt 5 is heated by the heating device 77 to a temperature of about 400 ° C or above warmed up. For the final cleaning, the fluidized bed cleaning device 75 is followed by a blow-out station 81, in which the filter belt 5 is blown with a hot air stream supplied via nozzles 83. Instead of or in addition to one or more of the devices 69, 75 and 81, other cleaning devices can also be provided which clean the filter belt 5, for example by means of pyrolysis or by burning out. Some of the devices 69, 75 or 81 can also be omitted or can be provided more than once.

Variants of the cleaning device explained with reference to FIGS. 1 to 3 are described below. Insofar as components already explained in the variants are provided, they are identified by the same reference numerals, but provided with a letter to distinguish them. To explain the structure and the mode of operation, reference is made to the preceding description.

FIG. 4 shows a variant of the cleaning device, which is distinguished primarily by the design of the outlet-side seal of the housing 1 a, by the construction of the transport device 13 a, which in turn gradually transports the endless filter belt 5 a, and by the design of the Scraping device 69a of the cleaning station 67a distinguishes. Otherwise, the construction corresponds completely to the construction of the cleaning device according to FIGS. 1 to 3, in particular also with regard to the design of the support body 3a and its support surfaces 7a, 15a and 17a provided with grooves 25a. The components 31, 37, 43, 47, 53, which are however present, are not shown in FIG.

While in the embodiment according to FIG. 4 the feed chamber 39a seals the inlet side by cooling, the outlet side of the cleaning device is sealed by a sealing strip 85 which extends over the entire width of the filter belt 5a and which is actuated by an actuator, here a hydraulic cylinder 87 between one the sealing position lying on the filter band 5a and a release position lifted off the filter band 5a. As will be explained in more detail below, the sealing strip 85 lies with its flat-ground side 89 facing away from the feed chamber 23a against a likewise ground flat sealing surface 91 of the housing 1a. In this way, the contact pressure required for sealing is generated by the pressure of the plastic melt in the cleaning device. During the operation of the cleaning device, the hydraulic cylinder 87 presses the sealing strip 85 against the filter band 5a. During the transport of the filter belt 5a, the feed pressure of the plastic melt in the feed chamber 23a is largely reduced, and the sealing strip 85 is lifted off the filter belt 5a.

The transport device 13a is combined with the housing la of the cleaning device to form a structural unit and comprises a linear guide 93, on which a clamping slide 97 can be moved back and forth along the filter belt 5a by means of a hydraulic cylinder 95. The clamping slide 97 has a clamping jaw 99 which is movable transversely to the plane of the filter belt and which is supported by a further hydraulic cylinder 101 between a clamping position in which it holds the filter belt 5a against a slide-side counter jaw 103 spans and a position releasing the filter band 5a is adjustable. When the clamping jaws 99 are tensioned, the transport device 13a can pull the filter belt 5a out of the cleaning device. When the jaws 99 are released, the transport device 13a can carry out a return stroke while idling.

The scraping device 69a of the cleaning station 67a is also combined with the housing la of the cleaning device to form a structural unit. The scraper 73a lies directly in the region o of the outlet gap on the filter belt 5a, which on the one hand has mechanical advantages and on the other hand avoids intermediate cooling of the residual plastic adhering to the filter belt 5a. If necessary, an additional heating device for preheating, as indicated at 71 in FIG. 1, can be used.

FIGS. 5 and 6 show details of a sealing device as used in a cleaning device according to FIG. 4 on the outlet side of the filter belt 5a

20 can. FIGS. 5 and 6 show the filter belt 5b in the region of the belt discharge chamber 41b formed by the housing 1b. The elongated sealing strip 85b is perpendicular to the plane of the filter belt 5b in a chamber 105 surrounding the filter belt 5b of a guide part 107 held on the housing 1b

2s movable between a sealing position in which the sealing strip 85b made of metal with an elastomeric, elongated seal 109 lies sealingly on the filter belt 5b and a raised position in which the filter belt 5b is released for transport. The sealing strip

30 85b extends beyond the edges of the filter belt 5b and, including these projecting end regions 111, lies with its side surface 113 lying forward in the transport direction against a sealing surface 115 of the housing 1b. The side surface 113 and the sealing surface 115 are ground flat and are

35 pressed tightly against each other by the pressure of the plastic melt. For driving the sealing strip 85b, a plurality of dowel pins 116 are provided in the guide part 107 on both sides of the plane of the filter belt 5b, which are loosely displaceable in the associated fitting bores 117 which extend in the displacement direction of the sealing strip. The dowel pins 115 and their associated fitting bores 117 have a circular cross section and can therefore be manufactured very precisely. At least in the area of the ends 111 of the sealing strip 85b there are dowel pins 116 opposite one another. For the actuation of the dowel pins 116, rod-shaped sliders 119 are guided in the longitudinal direction of the sealing strip 85b in the guide part 107. The slides 119 rest on the dowel pins 116 with inclined surfaces 121 inclined in the same direction, so that when the slider 119 is moved together by means of the hydraulic cylinder 87b, one of the sliders 119 takes the sealing strip 85b over the dowel pins 116, while the other slide 119 releases the dowel pins 116 . It goes without saying that other constructions can also be used to actuate the sealing strip. In particular, the sealing strip can also be firmly connected to the piston of the hydraulic cylinder, or separate hydraulic cylinders can be assigned to the sliders 119.

FIGS. 7 and 8 show details of a transport device 13c which can preferably be used in the embodiment of FIG. 4, including a preferred embodiment of a scraping device 69c for the filter belt 5c which is likewise combined with the housing 1c of the cleaning device to form a structural unit. The clamping slide 97c of the transport device 13c is slidably guided on two parallel linear guides 93c with counter jaws 103c parallel to the plane of the filter belt 5c and is moved back and forth by the hydraulic cylinder 95c. On a bridge 123 spanning the filter belt 5b, two hydraulic cylinders 101c are held at a distance from one another, which in turn guide the clamping jaws 99c movably perpendicular to the plane of the filter belt 5c. When the hydraulic cylinders 101c are extended, the clamping jaw 99c clamps the filter band 5c against the counter plate 103c, and accordingly the hydraulic cylinder 95c can pull the filter belt 5c out of the cleaning device when the clamping slide 97 is moved.

The scraper 73c is arranged below the filter belt 5c and is supported resiliently over the entire width of the filter belt 5c. While the holder 125 of the scraper 73c lies outside the housing lc, the scraper edge resting on the filter band 5c projects into the band discharge gap of the housing lc. The housing lc thus forms an abutment for receiving the contact pressure of the scraper 73c.

In the variants of the cleaning device explained above, the filter belt is designed as an endless filter belt. The use of an endless filter belt has the advantage that the filter belt can be cleaned continuously on average without having to interrupt the operation of the cleaning device for changing the filter belt. The filter belt can thus already be fed to the cleaning station 77 or 67a with comparatively little contamination, which means that the feed pressure of the material to be cleaned in the feed channel can accordingly be reduced. When the supply pressure is reduced, the filter belt is subjected to less mechanical stress, and its service life increases accordingly.

FIG. 9 shows a variant of the cleaning devices explained above, which differs from these devices primarily in that the filter band 5d is fed to the housing 1d of the cleaning device by unwinding from a supply roll 127 in the direction of an arrow 129. The filter band 5d, deflected by 180 ° in the housing 1d on the support body indicated at 3d, passes through a cleaning station 67d in the transport direction of the arrow 131 following the support body 3d before it is rewound onto a winding mandrel or the like of a winding arrangement 133. The filter band 5d wound in the winding arrangement 133 can, after the band winding has been moved into the supply winder. reuse. For the transport of the ^"filter band 5d, as indicated at 13d, to be a transport device is provided. In the transport device 13d may be arrangement to a pair of feed rollers or a Klemmzangen- as reference to the figures discussed 1 or 4 to act. The transport device 13d can either be arranged before or after the cleaning station 67d The material cleaning device as such expediently corresponds to the construction explained with reference to Figures 1 or 4. However, it can also be designed conventionally, for example with a cleaning chamber running straight through the filter belt Cleaning station 67d can be designed, as explained with reference to FIGS. 1 or 4.

Claims

Expectations

1. A device for cleaning viscous material, in particular a plastic melt from solid contaminants, comprising:

- a housing (1) with a feed channel (21, 23) for the material to be cleaned and a discharge channel (33) for the cleaned material, - a flow path of the material in the housing (1) between the feed channel (21, 23) and Discharge channel (33) sealingly penetrating filter band (5) displaceable in its longitudinal direction for separating the solid contaminants, - one on the side of the filter band (5) facing the discharge duct (33) fixedly arranged in the flow path with a support body (3) with a filter band (5 ) supporting support surface (7, 15, 17), the contour of which in a curved support surface area (7) deflecting the filter band (5) over a wrap angle of more than 90 ° essentially has the shape of a cylindrical surface, in particular a circular cylinder The surface follows and in both sides of the curved support surface area (7) in tangential and flush adjoining the curved support surface area (7) support surface area hen (15, 17) is substantially flat, with a plurality of mutually parallel and next to each other in the direction of displacement of the filter belt (5) extending towards the support surface (7, 15, 17) towards open grooves (25) at least in the curved support surface area (7), and with a multiplicity of passage channels (27, 35) extending from the grooves (25) for the passage of the cleaned material to the discharge channel (33), wherein the feed channel (21, 23) comprises a feed chamber (23) covering at least the area of the support surface (7, 15, 17) provided with grooves (25), - a transport device (13) for the continuous or step-by-step feed of the filter belt (5) .

2. Device according to claim 1, characterized in that the flat support surface areas (15, 17) at least in a partial area adjacent to the curved support surface area (7) with a plurality parallel to one another and extending in the direction of displacement of the filter belt (5), grooves (25) open to the support surface (7, 15, 17), from which passage channels (27, 35) for the passage of the cleaned material to the discharge channel (33) extend.

3. Apparatus according to claim 1 or 2, characterized in that the support body (3) to form the through-channels (27, 35) a plurality extending transversely to the grooves (25), the cross-sectional contour of several grooves (25) to form Has through holes (29) intersecting connecting channels (27).

4. The device according to claim 3, characterized in that the connecting channels (27) with a substantially centrally opening to them collecting channel (33) of the discharge channel are connected.

5. The device according to claim 4, characterized in that the passage channels (27, 35) within the support body

(3) run and include first channel sections (27) extending parallel to the cylinder-generating end of the curved supporting surface area (7) and are connected to the collecting channel (33) via radially running second channel sections (35).

6. Device according to one of claims 1 to 5, characterized in that the provided in a first portion of the support surface (7, 15, 17) grooves (25) within the support surface (7, 15, 17) and in one Grooves (25) provided within the support surface (7, 15, 17) and the grooves (25) of the second partial area relative to the grooves (25) of the first partial area start on the second partial area of the support surface (7, 15, 17) provided in the direction of displacement Gap are offset.

7. The device according to claim 6, characterized in that between the beginnings of the grooves (25) of the second portion of the support surface (7, 15, 17) run-up slopes (57) are provided on the support body (3).

8. The device according to claim 6 or 7, characterized in that the ends of the grooves (25) of the first portion of the support surface (7, 15, 17) and the beginnings of the grooves (25) of the second portion seen in the direction of displacement of the filter belt (5) are located approximately in the middle of the support surface (7, 15, 17).

9. Device according to one of claims 1 to 8, characterized in that the feed channel (21, 23) opens into the feed chamber (23) in a channel section (21) of the housing (1) which extends approximately radially to the curved support surface region (7), seen in particular in the circumferential direction of the curved support surface area (7) opens approximately centrally into the feed chamber (23).

10. Device according to one of claims 1 to 9, characterized in that the filter band (5) encloses the curved support surface region (7) of the support body (3) by approximately 180 ° and with at least approximately parallel, flat band sections within the housing ( 1) in a substantially flat Tape feed chamber (39) is guided to the curved support surface area and is guided away from the support body (3) in an essentially flat tape discharge chamber (41).

11. The device according to claim 10, characterized in that the tape discharge chamber (41) extends approximately tangentially to the curved support surface region (7) of the support body (3).

12. The apparatus according to claim 10 or 11, characterized in that the tape feed chamber (39) and / and the tape discharge chamber (41) by transversely to the plane of the band sections of the filter belt (5) guided therein by thermal insulation (55) in a the support body (3) near the temperature control zone and a cooling zone (49) remote from the support body (3).

13. Device according to one of claims 10 to 12, characterized in that the tape feed chamber (39) and / or the tape discharge chamber (41) extends at least in a partial area in the transport direction of the filter belt (5) transversely to the plane of the filter belt (5).

14. An apparatus for cleaning viscous material, in particular a plastic melt from solid contaminants, comprising:

- a housing (la) with a feed channel (21a, 23a) for the material to be cleaned and a discharge channel (33a) for the cleaned material, - a the flow path of the material in the housing (1) between the feed channel (21a, 23a) and Discharge channel (33a) sealed penetrating filter band (5a) which can be displaced in its longitudinal direction for separating the solid contaminants, - a support body (3a) arranged on the side of the filter band (5a) facing the discharge duct (33a) in the flow path and supporting the filter band (5a) with a In the form of a device comprising a transport means (13a) of the filter belt for continuous or stepwise advance (5a), in particular according to one of the - plurality of passage channels (27a, 35a) for the transit ^"occurs of the purified material to the discharge channel (33a)

Claims 1 to 13, wherein the filter belt (5a) is guided in a substantially flat belt feed chamber (39a) on the support body (3) and in a substantially flat belt discharge chamber (41) away from the support body (3), one of these chambers (39, 41), at least the

Belt discharge chamber (41) one transverse to the level of the filter belt

(5) movably guided by a drive device

(87) adjustable sealing strip between a release position located on the filter belt 85a)

(85), with their the flow path of the to be cleaned

Material facing away, transverse to the direction of movement of the

Filter bands (5a) over the entire width of the filter band

(5a) extending side surface (89; 113) is supported flat on a sealing surface (91; 115) of the housing (la).

15. The apparatus according to claim 14, characterized in that the side surface (113) of the sealing strip (85b) in the plane of the filter band (5b) protrudes over the longitudinal edges and also abuts the sealing surface (115) of the housing (lb) in this area .

16. The apparatus according to claim 14 or 15, characterized in that the side surface (89; 113) of the sealing strip (85a, b) and the sealing surface (91; 115) of the housing (la, b) are flat, ground surfaces.

17. Device according to one of claims 14 to 16, characterized in that the sealing strip (85b) consists of metal and on the filter belt (5b) facing it Side carries an elongated seal (109) made of elastomeric material.

18. Device according to one of claims 14 to 17, characterized in that the drive device (87b) via at least one cylindrical, movably guided in a fitting bore of the housing dowel pin (116) is in drive connection with the sealing strip (25b).

19. The apparatus according to claim 18, characterized in that on both sides of the sealing strip (25b) at least two dowel pins (116) are arranged at a distance from one another, the fitting openings (117) of which extend in the direction of movement of the sealing strip (85b) and that the drive device ( 87b) for actuating the dowel pins (116) drives inclined thrust surface elements (119, 121).

20. Device according to one of claims 1 to 19, characterized in that the transport device (13) along the direction of movement of the filter belt (5) hydraulically displaceable, hydraulically actuated clamping pliers (11, 57; 99, 103) for the filter belt (5) having.

21. The apparatus according to claim 20, characterized in that the filter belt (5) is designed as an endless belt and the

Clamping pliers (11, 57) clamp the filter band (5) between a deflection wheel (11) deflecting the filter band (5) and a clamping jaw (57) pressing against the circumference of the deflection wheel (11).

22. The apparatus according to claim 20, characterized in that the clamping pliers (99, 103) as a on a linear guide (93) along the filter belt (5) hydraulically displaceable carriage (97) is formed.

23. Device for cleaning viscous material, in particular a plastic melt from solid-state contamination, comprising:

a housing (1) with a feed channel (21, 23) for the material to be cleaned and a discharge channel (33) for the cleaned material,

a filter band (5) which penetrates the flow path of the material in the housing (1) between the feed channel (21, 23) and the discharge channel (33) and is displaceable in its longitudinal direction for separating the solid contaminants,

- One on the discharge channel (33) side of the filter belt (5) arranged in the flow path, the filter belt (5) supporting support body (3) with a

15 numerous passage channels (27, 35) for the passage of the cleaned material to the discharge channel (33),

- A transport device (13) for the continuous or incremental feed of the filter belt (5), in particular in the form of a device according to one of the

20 claims 1 to 22, wherein the filter belt is designed as an endless filter belt and passes through a cleaning station (67) offset in its feed direction relative to the support body (3).

24. The device according to claim 23, characterized in that the filter belt (5b) is guided in an endlessly rotating manner on at least one rotatably mounted deflection wheel (11) and at least one of the deflection wheel (11) is driven by the drive device (13b) as the drive deflection wheel

30 is formed.

25. Device for cleaning viscous material, in particular a plastic melt from solid-state contamination, comprising:

35 - a housing (ld) with a feed channel (21d) for the material to be cleaned and a discharge channel (33d) for the cleaned material, - A filter band (5d) which penetrates the flow path of the material in the housing (1) and seals between the feed channel (21d) and the discharge channel (33d) and can be displaced in its longitudinal direction to separate the solid particles.

5 per impurities,

a support body (3d), which is arranged on the side of the filter belt (5d) in the flow path and supports the filter belt (5d) and has a large number of passage channels for the passage of the cleaned material to the discharge channel (33d),

- A transport device (13d) for the continuous or incremental feed of the filter belt (5), in particular in the form of a device according to one of claims 1 to 22, wherein the support body (3d) in the feed path of the filter belt (5d) between a filter belt (5d ) dispensing supply winding arrangement (127) and a winding arrangement (133) receiving the filter band (5d) and that in the feed direction relative to the support body (3d)

20 a cleaning station (67d) is arranged between the support body (3d) and the winding arrangement (133), which passes through the filter belt (5c).

26. Device according to one of claims 23 to 25, characterized in that the cleaning station (67) in the feed direction of the filter belt (5) successively comprises a scraping device (69) and subsequently at least one cleaning device (75, 81).

30. The device according to claim 26, characterized in that the scraping device (69) preheating the filter belt (5) heating means (71) and the at least one subsequent cleaning device (75) heating means (77) increasing the temperature above the preheating level.

35 are assigned.

28. Apparatus according to claim 26 or 27, characterized in that at least the one subsequent cleaning device is designed as a fluidized bed cleaning device (75).

29. Device according to one of claims 26 to 28, characterized in that at least one cleaning device, in the case of a plurality of cleaning devices, the last cleaning device in the feed path of the filter belt (5) is designed as a blowing device (81), in particular a hot air blowing device.

30. Device according to one of claims 1 to 29, characterized in that the housing (1) is designed to be divisible and comprises an optionally multi-part, removable wall section (61) which guides the guide path of the filter belt (5) at least along one of the edges of the filter belt (5) covers the entire length of the filter belt (5) running within the housing (1).