DE102007045664B3 - Method and device for removing dust and / or fibrous admixtures from a plastic granulate - Google Patents

Abstract

The invention relates to a method and apparatus for removing dust and / or fibrous admixtures of a plastic granules, in which the granules are directed to at least one perforated inclined surface in a closed elongated housing of a cleaning device and cleaned by air currents, the dust - And / or fibrous admixtures cleaned granules is discharged and the holes in the inclined surface are smaller than the granule size. The granules are fed via a separator of the cleaning device. The individual granules are caused by mechanical action, by an introduced air flow and / or by a predetermined drop height to jump on and along the inclined surface. Above the inclined surface, an air flow is introduced into the cleaning device distributed. Below the inclined surface, a suction channel is provided with at least one suction for a Luftabsaugvorrichtung. At the end of the inclined surface, the purified granules are discharged via an outlet into a collecting container.

Description

The Invention relates according to the preamble of Anspruchs 1 a method for removing dust and / or fibrous impurities from a plastic granulate.

The Invention further relates to a cleaning device according to claim 7th

From the DE 100 54 418 A1 are a method and an apparatus for removing dusty and fibrous admixtures of bulk material, which consists of particles, in particular granules, known. The bulk material is passed on at least one inclined surface of an air classifier and fluidized. The fluidized bulk material flow is subjected to sharp air jets transversely to a flow direction in order to achieve a separation between dusty and fibrous admixtures on the one hand and cleaned bulk material on the other hand, the air jets lead to a slowing, nearly vertical air flow in the separation area, which is adjusted so that the heavy particles of bulk material fall out of the air stream, while the lighter dusty and fibrous impurities are discharged with the air stream. This method and the device are relatively complicated, elaborate and require a fluidized bulk flow.

From the DE 12 13 387 A is a device for dedusting granules, in particular of plastic granules, according to the principle of current classification known. This device has a vertical separating tube, which opens with its lower end in a reservoir for receiving the granules and its upper end terminates in two concentrically arranged tubes, wherein the cross-sectional area of the outer annular space is dimensioned such that the rate of rise of the liquid in the outer annulus is approximately equal to the rate of rise in the separation tube and at the top of the circumference of the outer tube an outlet for the laden with dust separating liquid is provided. Again, it is a wet process that is extremely expensive.

Furthermore, from the DE 12 33 700 A a method for cleaning plastic granules of adhering dust particles known in which the Sichtgut trickles down in free fall on a spray electrode. The dust particles dissolved by the granules are separated from the granules by means of the gas stream deviating from the granulate stream. This ensures that the individual granules very often come into contact with the spray, evenly charge and thereby solve the adhering dust particles by mechanical and electrostatic action and be taken from the gas stream. This method and the device for this are very complex and require special device components and process control systems.

From the DE 17 86 277 A is a device for electrostatic discharge of running webs and their simultaneous dedusting known. For this purpose, an ionization electrode equipped with a ventilation system is provided on the inlet side of a suction box extending over the width of the web and arranged at a small distance from the web above and / or below it, connected to a suction fan. By arranged on the inlet side of the suction box ionization electrode, the incoming into the suction box train with ionized gas, preferably air, is applied. Both the web and the dust adhering to the surface are electrically neutralized. By neutralizing the electrostatic adhesive forces between the web and dust particles are removed, so that the latter are removed by the suction of the suction device with the gas or the air from the suction box. Air can be used as the gas or else a protective gas, ie an inert gas, preferably nitrogen. This avoids ozone formation at the spray tips of the electrodes.

The DE 558 456 A describes a coal and mountain shearing method using a skimmer, wherein the coal is carried along with the mountains on a sloped surface having no breakthroughs, but a defined arcuate shape opening into a gap provided as a separation gap. The good bounces on the inclined divisional surface line by line in such limited quantities and at such intervals that the jumping or bouncing as a result of the collision moving coal parts ahead of the accompanying mountain parts, but not catch up to the skip gap the remaining mountain portions of the previous line. Through the given ramp, a skip of the separation gap is achieved by the coal, while the mountains come into the separation gap.

The DE 195 32 770 A1 indicates a continuously operable air jet screen with a fine hopper and a coarse material chute, which has a substantially flat, designed as a bottom of a closed vibrating conveyor screen surface and disposed in the fine hopper of the screen surface nozzles. Furthermore, a vibration drive for achieving a relative movement between the screen surface and the nozzles is provided. Below the screen surface at least two nozzles are mounted in a fixed position transversely to the conveying direction of the vibrating conveyor, wherein an oscillating air flow is passed through the nozzle to the screen surface. Through the air supply is to be achieved that the screen mesh is freed of pinch, loosening occurs and the transport and distribution of the screenings are ensured on the screen deck. The air flow is thereby added from below the screen mesh. The airflow promotes locomotion and the cleaning effect, while locomotion is ensured by the vibration drive acting on the screen mesh. While the fines fall through the mesh of the mesh, the coarse material falls into a coarse well.

Of the The present invention is based on the object, a method and a device for removing dust and / or fibrous additives from a plastic granulate, which can be realized with very simple means, have a high efficiency and in a plastic processing plant usually existing facilities can be created.

The Task solves the invention by a method as specified in claim 1 is, and by a cleaning device according to the teaching of claim 7.

The inventive method provides that the granules are not in a granular stream of the cleaning device supplied is, as is the case with known devices, but that a separating device is connected upstream, for example a screw conveyor may be the single granules in series or a few granules at the same time outputs. These are about the Inlet fed to an inlet plate, the opposite the bevel in one certain distance and / or inclination is arranged so that the granules on the stretched or hard Beveled and in jumps to move on the inclined surface, where the jump heights steadily decrease. This jumping behavior can be achieved by targeted introduction an air or gas stream are supported on the inlet plate, to vibrate this or accelerate the granules. The Air can be entered pulsating. It goes without saying even that z. B. used compressed air, for example from a Coming Compressor must be filtered to avoid any contamination to achieve. But it is also possible the jump effect over the total length of the housing too promote, by over Nozzles distributed an air flow is generated after the impact of a granulate on the inclined surface this let go again. The Jumping of the individual granules can also be achieved by coupling cause the inlet plate with a vibrator on the sheet acts and this vibrated. The jump height should be at the first jumps greater than about 40% of the distance height between the housing top wall or cover and the oblique surface, for example, about a length the bevel of about 40 to 120 cm given at least seven to ten jumps are.

The casing can be an elongated case with rectangular, be edgewise cross section. The inclined surface runs parallel to the ground in one Distance, the z. B. is less than 30% of the height. In the space between bevel and Ground the suction channel is provided. The top cover runs parallel to the inclined surface. The banking the bevel is going through bevel Installation of the housing reached in the machine frame and should be between about 5 degrees to 25 degrees incline. The tilt is required to Downward jumps of the granules to reach. The inclined surface can but also as such in the case obliquely provided be. In this case, the cover should also be diagonally parallel run to such a big one Distance to achieve that the granules can jump freely.

The according to the inventive Procedure forced jumps the individual granules cause the impact on the inclined surface, the perforated or from a wire or plastic mesh grid exists and is very taut, the adhering dust particles are peeled off, while the cleaned granules continue to jump until it is the end of the Sloping surface achieved and falls into an outlet section in the housing and therefrom via an outlet in a collection container flow can, of course Dust-proof must be completed to avoid any re-contamination to obtain.

Around the detached dust particles from the surface or the edges of the breakthroughs to remove the bevel, is a suction channel over the whole length the inclined surface running provided below this, to which a suction device connected is sucked with the contaminated with dust particles air becomes. As a suction device, an industrial vacuum cleaner has become more common here Kind of proven, its suction power can be adjusted by speed control of the motor can. So it is possible any desired on the granule size and the Granulate weight to generate coordinated suction. The air supply usually takes place from an existing compressor plant in an industrial enterprise using interposed Filter. The air is over brought the provided on the inside of the cover nozzles. The cleaned, a collection container supplied Granules can then by means of a conveyor a dryer or a distribution system or the feed containers of a plastic processing machine directly supplied become.

Around To improve the detachment of the dust particles, the air in the housing partially or over the entire length the inclined surface ionizes , thereby neutralizing the electrostatic adhesive forces between Granules and dust particles in a known manner, as described above, is effected. It can be seen that by the jump effect, the here for the blast is exploited, the granules of ionized air over the Time of the jump to be suspended, and that on all sides, so that As a result, a particularly high degree of effectiveness with respect to the neutralization of electrostatic adhesive forces given is.

Instead of of compressed air can also be an invert gas, especially carbon dioxide, continuously or intermittently over the Nozzles initiated become. As an inclined surface can a perforated sheet metal with small holes or a braided Wire mesh or a plastic mesh can be used with mesh. These be clamped so that the fabric or grid is taut and practically provides a baffle floor.

The ionizing can over the whole length the inclined surface running in the case be provided. The housing is a rectangular one casing with a higher one Longitudinal than Width extension with an inclined surface arranged parallel to the ground and a suction channel underneath. By inclination of the housing Overall, the inclined surface is on realized in a simple way. For this purpose, the housing in a Machine frame diagonally be installed. This is a constant distance of the inclined surface to Cover or ionization start and given to the nozzles over the introduced the air for further transport of the jumping granules becomes. Since both the separating device and the connected Vacuum cleaner and the collection container, coupled with a conveyor is, have to be controlled Furthermore, an electrical control device is provided, the The machine frame is attached to this the central control of all three components and the air delivery controls.

Around with different types of plastic and granule sizes an adapted separation to be able to make the granules, the separating device can also be a metering device, for example a controllable by a setting wheel feeder, to the continuous Supply of individual granules to allow. The separating device should be located above the inlet on the housing and in known manner from a feed container and a worm drive for transporting the granules from the feed container.

The Sloping surface can from a perforated sheet metal, a braided wire mesh or from a plastic fabric with mesh or from longitudinal and / or transverse and / or diagonal slotted sheet or plastic. The slots can also provided in defined angles to the longitudinal axis of the inclined surface be. The hole sizes or The gap widths are to be chosen so that the on the granules Although adhering contaminants can fall through, but the granules on the surface is moved, in leaps and bounds, as indicated according to the invention is. The can Perforations or the mesh of the plastic fabric or the slots be provided throughout. The bevel can also be divided into fields be that punched or made of a plastic fabric with mesh or consist of a braided wire mesh or longitudinal and / or cross-slotted. The slots can also be at an angle to longitudinal axis run. So it is possible, for example, after the enema one provided perforated plate, behind a braided wire mesh and behind it again a slotted sheet metal. As a particularly advantageous it has proved, if the first field after the enema a slotted Field is. This should include all the other fields as well separately removable be. The slit has the advantage of having hair or other longer fibers fall into or through the slits and then sucked down can. Would the first Field could be a hole field, so could the hair ends in the holes get caught without them z. B. be removed with a vacuum cleaner can. By removable design The fields are also easy to clean. The effect is however also achievable by slotting over the entire length of the Sloping surface runs. Instead of a Feldes with slotted sheet or a plastic plate but can also a rake be integrated, which has longitudinal slots and off Round bars exists. these can even sharpened on the front for easier picking up to ensure long fibers or hair. Also this rake must be cleaned if necessary. Through the slots or the rake is to be excluded that longer Fibers, e.g. B. hairs that are in the granular stream and on the Singulator and enter the inlet into the device housing, be dispensed with the purified granules. The slots or the rakes do not interfere with the jumping of the granules by themselves but the ends of the long fibers on. Thus a cleaning of the rake or the slotted portion or the entire slanted surface should this removable in the housing be stored above the air channel.

Furthermore, the housing may, of course, also have side walls which are transparent to better facilitate the jumping of the granules and, if necessary, to be able to influence the generation of vibrations or the pulsating air supply, if these support the triggering of the jump.

The advantageous method steps are in the dependent claims 2 to 6 indicated. Advantageous embodiments of the cleaning device specified in claim 7 are in the claims 8 to 21 indicated.

The Invention will be described below with reference to the figures embodiment a cleaning device for Granules described in addition.

In the drawings shows:

1 a schematic representation of a cleaning device for granules of plastic according to the invention,

2 an extract from the housing with inlet area,

3 the formation of the inside of the cover of the housing of the cleaning device,

4 an example of an inclined surface according to the invention with individual rake-shaped fields and

5 a highlighting of the section A from the inclined surface 4 with clearly visible tines of two arithmetic fields and their course.

In 1 is a machine frame 17 shown. At this machine frame is a housing 1 the cleaning device mounted obliquely. It is an elongated box-shaped housing with a cover 18 , The side walls of the housing 1 have transparent panes 19 so that an insight into the interior is granted. For simplicity, the visible therein inclined surface, which is due to the inclination of the housing 1 results, not shown. This is off 2 seen. It is a perforated metal sheet or a wire mesh with openings. These breakthroughs are smaller than the diameter of the smallest granules, but larger than the dust particles, so that the granules on the inclined surface 2 can jump along in the desired manner. Below the Schrägflä surface 2 is a suction channel 4 provided, the suction ports in three places 5 having. These connections 5 are merged and via a suction hose 20 with the air suction device 6 connected, which may be, for example, an industrial vacuum cleaner, its suction through the adjuster 21 is adjustable. The inclined surface 2 ends in an outlet chamber into which the purified granules fall and over the outlet 7 the collection container 8th is supplied. The collection container 8th is part of a conveyor and hermetically sealed, so that the granules are no longer contaminated. About the transport unit 22 of the collection container, the granules are then a dryer or the plastic processing machines on the connection 23 and supplied to pipes not shown. 1 further shows that on the machine frame 17 above the inlet 13 for the granules a separating device 3 is mounted. This has a doser on the dial 24 is adjustable. Above the meter is a container 25 arranged, over the supply line 26 the granules are supplied. Out of the container 25 be via a screw conveyor of the singulator 3 taken the granules. The feeder is via an adjuster 27 adjustable. The electric drives and possibly also the valves in the compressed air supply line via a central electrical control unit 16 controlled. The cabling is not shown.

The granules pass through the separating device 3 and the inlet 13 in the case 1 , on the in 2 that a section of the case 1 shows, illustrated inlet plate 10 , This is at a certain height to the inclined surface 2 arranged, which has a variety of through holes 11 having. The granules fall from a certain height on this surface and thus jumps back up, which is favored by the introduction of the air above. Furthermore, an air jet can be directed to the sheet to accelerate the Gra nulat the first jump. The continue on the off 3 visible air nozzles 14 that over the length of the case 1 distributed, provided air supply also supports the jump effect. Every time a granulate hits the beveled surface 2 adhering dust particles are blasted off and fall through the holes or through the holes from the air suction device 6 sucked so that at the end of the inclined surface 2 cleaned granules is applied, which can be removed.

To neutralize the electrostatic adhesive forces between granules and dust particles, as can be 3 visible on the inside of the cover 18 at least one ionization bar 9 be provided, in the embodiment, these are two, the side to the air nozzles 14 are attached. These two ionization bars 9 make sure that the air is ionised, which neutralizes the electrostatic adhesion forces, so that when the granules hit the beveled surface 2 the adhering dust particles are blasted off. Because the cracks of the granules over the entire length of the housing 1 done, it can be seen that the Granu Each time it is immersed in the ionized air and lapped by it, so that at the end of the passage of the inclined surface 2 Also any dust particles are blasted from the granules.

It is from the illustration in 1 It can be seen that the system which is necessary for the realization of the method is of very simple construction and can be put together in a production plant by means of a commonly available device and can be produced inexpensively.

In 4 is an oblique surface 2 represented in the form of a slotted sheet with advantageous dimensions of the embodiments and in 5 an enlarged excerpt A from this sheet metal strip. The inclined surface 2 is how it looks 4 can be seen from a metal strip in which arithmetic fields 28 by slitting and free cut - distributed over the length - are introduced. These arithmetic fields 28 consist of free-cut tines, which are tongue-shaped and frontally cut straight in the direction of the granules. These faces form with the opposite cut surface of a calculation field 28 in the metal strip a gap 30 , The slot widths and the width of the gap 30 are chosen so that the granules can not fall through, but the impurities that are blasted off this, or even fibers or hair can fall through. Are z. B. transported hair over the inclined surface, so the ends in the slots - the slot width is z. B. 1.5 mm - hook and through the gap 30 - In the exemplary embodiment 1.75 mm - fall into the underlying suction. The individual tines have surface shape and are, for example, 3.8 mm wide. Each of the arithmetic fields 28 For example, has a dimension of 60 × 85 mm with a total width of the inclined surface 2 of 113 mm. In the inlet area has the inclined surface 2 an 80 mm wide inlet zone below the inlet plate, not shown.

1

casing

2

sloping surface

3

separating device

4

suction

5

suction

6

air extractor

7

outlet

8th

Clippings

9

ionizing

10

infeed plate

11

Through holes

12

Facility

13

inlet

14

air nozzles

15

dosing

16

central electrical control

17

machine frame

18

Cover / lid

19

slices

20

suction hose

21

adjuster

22

transport unit

23

connection

24

dial

25

container

26

supply

27

adjuster

28

calculation fields

29

prong

30

gap

Claims (21)

Process for removing dust and / or fibrous admixtures from a plastic granulate, in which the granules are deposited on at least one perforated oblique surface ( 2 ) in a closed elongated housing ( 1 ) is passed to a cleaning device and cleaned by air streams, wherein the cleaned of the dust and / or fibrous impurities granules is discharged, and the holes in the inclined surface ( 2 ) are smaller than the granule diameter, characterized in that - the granules are separated by a singling device ( 3 ) is supplied to the cleaning device, - that the individual granules by mechanical action, by an introduced air flow and / or by a predetermined drop height for jumping on and along the inclined surface ( 2 ) are caused, - that above the inclined surface ( 2 ) in the housing ( 1 ) of the cleaning device, an air flow is introduced distributed, - that below the inclined surface ( 2 ) a suction channel ( 4 ) with at least one suction connection ( 5 ) for an air extraction device ( 6 ) is provided and the contaminated with the dust and / or fibrous impurities air is sucked, and - that at the end of the inclined surface ( 2 ) the purified granules via an outlet ( 7 ) in a collecting container ( 8th ) is discharged. Method according to claim 1, characterized in that the air in the housing ( 1 ) partially or over the entire length of the inclined surface ( 2 ) above it by means of at least one Ionisationsstabes ( 9 ) is ionized to neutralize the electrostatic adhesive forces between granules and dust particles. A method according to claim 1, characterized in that the granules by applying an inlet sheet ( 10 ) with air or by vibration generation by means of electromagnetic or acoustic vibrator is caused to jump. A method according to claim 1 or 3, characterized in that the jumps by the attachment of the inlet sheet ( 10 ) at a certain height to the inclined surface ( 2 ) To be defined. Method according to claim 3, characterized that the air is compressed air or an inert gas, in particular carbon dioxide, and continuously or intermittently is initiated. Method according to claim 1, 2 or 5, characterized that the fed Air is filtered. Cleaning device for removing dust and / or fibrous admixtures from a plastic granulate, comprising - a closed, elongated housing ( 1 ) and a perforated oblique surface ( 2 ) with through holes ( 11 ), which are smaller than the diameter of the individual granules, in the housing ( 1 ) leading to the upper wall of the housing ( 1 ) is located at a certain distance, - a facility ( 12 ) to the top-side inlet of at least one air flow into the housing ( 1 ), - a suction channel ( 4 ) below the inclined surface ( 2 ) with at least one suction connection ( 5 ), - a separating device ( 3 ) for feeding the granules to the housing ( 1 ), - one with the singulator ( 3 ) coupled, at a certain distance from the inclined surface extending arranged inlet plate ( 10 ), which is continuously or intermittently acted upon by an air flow or is in communication with a vibration generator and / or which is arranged at a defined distance above the inclined surface and predefines a defined drop height, whereby the individual granules for jumping in several jumps over the length of the Inclined surface ( 2 ), - an outlet ( 7 ) at the outlet end of the housing ( 1 ) with a connection to a collecting container ( 8th ) and - an air suction device ( 6 ) connected to the exhaust port ( 5 ) is connectable. Cleaning device according to claim 7, characterized in that the oblique surface ( 2 ) consists of a perforated metal sheet, a braided wire mesh or a plastic fabric with mesh or longitudinal and / or transverse slotted sheet or plastic panels or such with running at a certain angle to the longitudinal axis slots, wherein the perforation, braiding or slotting over the length of the inclined surface is provided in a continuous or divided into fields, wherein the individual fields have the same and / or different perforations and / or slits and / or sizes. Cleaning device according to claim 7, characterized in that partially or over the length of the inclined surface ( 2 ) above the same at least one Ionisationsstab ( 9 ) is provided. Cleaning device according to claim 9, characterized in that at least one Ionisationsstab ( 9 ) over the entire length of the inclined surface ( 2 ) running on the cover ( 18 ) in the housing ( 1 ) of the cleaning device is provided. Cleaning device according to claim 7, characterized in that the separating device ( 3 ) has a screw through which the granules are metered onto the inlet plate ( 10 ) can be introduced. Cleaning device according to claim 7, characterized in that that in the air supply to generate the cracks of granules a controllable valve or a vibrating valve is arranged, which controls the air flow in pulses. Cleaning device according to claim 7, characterized in that an electromagnetic vibration generator or a motor with an eccentric mechanically with the inlet plate ( 10 ) connected is. Cleaning device according to claim 7, characterized in that on the inlet plate ( 10 ) An acoustic transducer is mounted, which sets the inlet plate in vibration. Cleaning device according to claim 7 or 8, characterized in that in the oblique surface ( 2 ) at least one calculation field ( 28 ) with tines ( 29 ) is arranged, which run either opposite to or in the jump direction of the granules, and that at least the arithmetic field ( 28 ) is removably mounted. Cleaning device according to claim 15, characterized in that the tine length ≥ 1/15 of the length of the inclined surface ( 2 ). Cleaning device according to claim 7, characterized in that in the cover ( 18 ) of the housing ( 1 ) over the length of the inclined surface ( 2 ) distributed in a certain grid air nozzles ( 14 ) are arranged. Cleaning device according to claim 7, characterized in that the separating device ( 3 ) a stepwise or infinitely adjustable and / or controllable dosing unit ( 15 ) having. Cleaning device according to claim 7, characterized in that a central electrical control ( 16 ) is provided for the connected components. Cleaning device according to claim 7, characterized in that at least the housing ( 1 ) in a machine frame ( 17 ) and that the separating device ( 3 ) above the inlet ( 13 ) is attached. Cleaning device according to claim 15, characterized in that the tines ( 29 ) tongues which are cut free on three sides and which, together with their free ends and the face-facing cut-off surface in the oblique surface (FIG. 2 ) a gap ( 30 ), which is smaller than the diameter of the granules.