EP0933142B1 - Method for the pneumatic classification of toner - Google Patents

Method for the pneumatic classification of toner Download PDF

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Publication number
EP0933142B1
EP0933142B1 EP99100551A EP99100551A EP0933142B1 EP 0933142 B1 EP0933142 B1 EP 0933142B1 EP 99100551 A EP99100551 A EP 99100551A EP 99100551 A EP99100551 A EP 99100551A EP 0933142 B1 EP0933142 B1 EP 0933142B1
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EP
European Patent Office
Prior art keywords
classifying
toner
zone
classification
toner product
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EP99100551A
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German (de)
French (fr)
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EP0933142A3 (en
EP0933142A2 (en
Inventor
Marcus Dipl.-Ing Adam
Stefano Dipl.-Ing. Zampini
Bodo Dr.-Ing. Furchner
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Hosokawa Alpine AG
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Hosokawa Alpine AG
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
    • B07B7/00—Selective separation of solid materials carried by, or dispersed in, gas currents
    • B07B7/08—Selective separation of solid materials carried by, or dispersed in, gas currents using centrifugal force
    • B07B7/083—Selective separation of solid materials carried by, or dispersed in, gas currents using centrifugal force generated by rotating vanes, discs, drums, or brushes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
    • B07B11/00—Arrangement of accessories in apparatus for separating solids from solids using gas currents
    • B07B11/06—Feeding or discharging arrangements
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/0802—Preparation methods
    • G03G9/0817—Separation; Classifying

Definitions

  • the present invention relates to the manufacturing process of a toner certain grain distribution for the development of electrostatically generated images, in particular on a visual procedure to set the required Grain distribution as a means of achieving excellent quality of the toner product.
  • the manufacture of prior art toner involves blending suitable components, extruding, cooling and the subsequent Crushing.
  • the shredded material is then subjected to a screening remove unwanted particle fractions and create a product with the desired Obtain particle size distribution.
  • the particle size distribution (PGV) is usually on a Coulter Counter Multisizer from Coulter Electronics, Inc. (USA) measured and is a number distribution.
  • the aim of the sighting is usually a Separation of very fine particles in the range below 5 ⁇ m, but sometimes also one Upper grain limit or both together.
  • the object of the invention is to provide a process for producing Toner that solves the problems described above and enables a toner with a required, narrow particle size distribution as effectively as possible manufacture. Another task is to provide a process for it enables the fine fraction of the product to be reduced. Furthermore, it is about a process in which both the fine fraction and the top grain are reduced can be limited, whereby a narrow particle size distribution by sighting is achieved with a directed material guide, the starting material the screening by mixing, extruding and crushing a basic mixture was obtained.
  • the object of the invention is achieved in that a even distribution of the toner product over the circumference of the classifier wheel is achieved, the toner product in a directional material guide in the direction of Gravity is guided through the viewing zone and to control the dwell time of the toner product means are provided in the viewing zone, in the upper area the toner product in the homogeneous state quickly into the viewing zone bring the toner product in the middle of the field of view longer let it linger and one in the lower area of the visual zone enable rapid removal of the toner product from the viewing zone.
  • the feed material coming from the crushing process becomes one or subjected to several sightings, depending on whether only one dedusting or one combined dedusting / upper grain limitation is required.
  • sole Dedusting is obtained as a coarse fraction that represents the product and one Fine fraction that can be recycled.
  • With a combined Dedusting / upper grain limitation gives you a fine fraction, a coarse fraction and a middle fraction representing the product.
  • ⁇ ges ⁇ 1 xn a with 1 ⁇ a ⁇ 1.6
  • the value 1.3 is preferably chosen for a. This results in triple Sighting a possible loading from 0.2 to 0.83. Of course there is also one multiple sightings in the range of a ⁇ 1 possible. This will make the product quality optimized for maximum coarse material.
  • a vertical-axis air classifier is used, the one central feed with tangential, arranged at the level of the classifier rotor Visual air supply, a fixed one on the circumference of the classifying rotor in radial Spacer vane ring, an annular one through one mounted paddle wheel classifier rotor and a coaxial at a radial distance from The outer circumference of the classifying rotor arranged guide vane ring limited Visual space, a drive shaft for the classifier rotor mounted on one side and a Has housing with fine and coarse material outlet.
  • the material to be sifted is fed in centrally and spread over a spreading plate distributed and bell-shaped over the outer circumference of the classifying rotor evenly distributed good veil passed past the classifier wheel blades.
  • the classifying wheel is flowed through by the classifying air from the outside in and that Fine material directed into the interior of the classifier rotor.
  • the rejected coarse material follows gravity continues and is surrounded by an annular coarse material discharge area added.
  • the visible air flows radially from the outside to the inside.
  • the rotating paddle wheel rejects the coarse material radially outwards and the fine material together with the classifying air into the interior of the classifying rotor transported.
  • the fine material sighted is then led axially downward Redirected direction and then out of the classifier rotor through the broken through drive shaft.
  • the section of the drive shaft 2 penetrating the fine material discharge space is designed as a perforated shaft part, the support device 10, and thereby enables the fine material to pass from inside the classifier wheel 8 into the fine material discharge space 14.
  • This support device 10 comprises the base plate 18, the washer 17, and the aerodynamic spacer webs 10a and form a connecting link between the drive shaft 2 and classifier wheel 8 and the passages for the discharge of the fine material from the inside of classifier wheel 8.
  • the classifier wheel 8 consists of the classifier wheel vane ring 9, the lens 16 and the cover plate 15 and is rotatably connected to the support device 10 .
  • This connection in the area of the discs 15 and 17 can be designed releasably and z. B. by screws 19 arranged uniformly over the circumference of the classifying rotor.
  • a seal 20 that can be flushed with a fluid is shown in an axial arrangement and reliably separates the visible space 21 from the fine material outlet space 14.
  • the lower cover disk 15 projects beyond the inner diameter of the annular disk 17, and thus over the support device 10 into the interior , and thus forms an orifice with a throttling effect in the transition area.
  • the goods are placed on the cover plate 16 of the classifying wheel 8, which forms a diffusing plate.
  • the annular channel between the outer diameter of the classifying wheel 8 and the inner diameter of the guide vane ring 13 forms the classifying space 21 over the height of the classifying wheel 8 .
  • the visible material 21 flows through the visible space 21 in the vertical direction.
  • a screw spiral 29 extends almost over the entire radial width of the visible space 21 and extends over the entire height of the classifying wheel 8 .
  • a single helical screw with a constant pitch is used.
  • the sifting air flow runs perpendicular to the sifting material flow.
  • the classifying air from the classifying air inlet 22 passes horizontally through the fixed guide vane ring 3 into the classifying chamber 21 and flows through it perpendicularly to the classifying material flow.
  • the fine material sighted is discharged axially with the classifying air via the fine material outlet 23 .
  • the coarse material sighted is discharged through the coarse material discharge space 13 below the viewing space 21 via the coarse material outlet 24 .
  • the coarse material discharge ring 25 is fixedly connected to the classifying wheel 8 and rotates within the coarse material discharge space 13.
  • the fixed retaining ring 26 is arranged above the coarse material discharge space 13 and is fixedly connected to the housing 1 .
  • the gap 27 for the introduction of the scavenging air 28 is located between the bottom of the coarse material discharge space 13 and the coarse material discharge ring 25 .
  • the drive shaft is arranged above the classifying wheel and penetrates the product feed area.
  • the material is fed in centrally from above through the ring-shaped feed opening 220 onto the classifying wheel 221.
  • the material is thrown outwards against the impact ring 222 and is thus distributed evenly over the circumference. It then falls into the viewing gap between the blade ring 223 and the classifying wheel 221, where it is flushed by the classifying air.
  • the classifying air enters the classifying chamber through the spiral housing 224 , flows through the classifying wheel 221 and leaves the classifier together with the fine material downward in the direction of gravity through the fine material outlet 225.
  • the blade ring 223 is equipped with one or more screw spirals 226 in order to increase the dwell time to control the material. For various visual tasks, e.g. B. Coarse or fine sighting, different blade rings can also be used.
  • a screening process according to the invention for dedusting which includes the screen type described above, is shown in FIG. 3.
  • the task is carried out from above by a suitable metering element 301.
  • the ratio of sifting air volume flow to feed mass flow should be in the range from 0.05 kg / m 3 to 0.3 kg / m 3 , preferably 0.1 kg / m 3 .
  • the classifying air enters classifier 306 through classifying air inlet 304 and is drawn in by fan 309 through classifier 306 into an optional cyclone 307 and filter 308 .
  • the blower 309 is adjusted so that air velocities in the range of 3 m / s to 7 m / s are present on the outer edge of the classifying wheel.
  • the peripheral speeds of the classifying wheel for a fine sighting are between 40 m / s and 65 m / s, for a rough sighting they are preferably in the range of 20 m / s to 45 m / s.
  • the process mentioned here can either be operated with a downstream cyclone 307 and a filter 308 or only with a filter 308 .
  • the selected fine material is first fed to the cyclone 307 via the fine material line 318 and the essential part is separated from the classifying air and can be discharged via the fine material discharge 303 .
  • Ultrafine particles that were still entrained with the visible air settle on the filter 308 and can be removed via the dust discharge 305 after being blasted off from the filter material.
  • the finished product is obtained via the coarse material discharge 302 .
  • Fig. 4 shows such a system scheme for a combined rough and Fine sighting and double fine sighting.
  • the material is first subjected to a fine screening analogous to FIG. 3.
  • the product to be processed is the coarse material from the first screening and is fed to the product task of the second classifier 410 via the line of the first coarse material discharge 402 .
  • the feed material is subjected to a rough screening in order to limit the top grain, i.e. the fine material obtained in the second screening from the cyclone 411 and the filter 412 is obtained via the fine material discharge 416 and the dust discharge 417 and represents the actual product
  • the very coarse fractions, the grain diameter of which is above the desired upper grain limit, are discharged via the coarse material discharge 415 and can be discarded or, for example, re-ground.
  • the particle size distribution curves are measured in diagrams 1 and 2 with a Coulter Counter Multisizer from Coulter Electronics, Inc. (USA). The goal was to remove dust by separating the Fine particles below 5 ⁇ m.
  • the starting material has a very high proportion of fine material and thus represents a low quality toner.
  • Diagram 1 shows the product improvement as it is achieved by a two-stage fine sighting according to the invention according to FIG. 4 becomes. It can be clearly seen that the first sighting is far can remove most of the fine dust below 5 ⁇ m. Through the following the second fine screening, the proportion of fine dust is increased again by approx. 50% reduced. The finished sighted product shows a very high slope above the separation limit of 5 ⁇ m. By the method according to the invention thus achieved a very sharp separation.
  • the particle size distribution curves are one sighting according to the invention with a controlled dwell time of the material to be sighted Sighting without such control using the same Sifter types and the same sifter settings are compared.
  • the Control of the dwell time of the material to be viewed in the viewing zone can, otherwise same visibility conditions, much more fine dust from the sight be separated.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Combined Means For Separation Of Solids (AREA)
  • Developing Agents For Electrophotography (AREA)
  • Control Or Security For Electrophotography (AREA)

Abstract

A rotary disc (16) distributes toner evenly over the classification rotor (8) circumference. The toner descends under gravity, being guided through the classification zone (21). A spiral controls toner residence time distribution from top to bottom of the classification zone. Toner is introduced quickly in the homogenous state at the top and resides for a longer interval in the central part of the classification zone. At the bottom it is carried away continuously. Classification air driven past the outer edge of the rotor flows at a mean velocity of 3-7 m/s. The ratio of mass flowrate of toner to volumetric airflow is held at 0.05-0.3 kg/m<3>, based on product weight. Residence time is controlled by a coaxial spiral (29) around the classification rotor. This occupies only part of the radial extent of the classification zone. Over its length, the pitch of the spiral varies. Toner mass flowrate to classification air volumetric flowrate is preferably 0.1 kg/m<3>. Mean velocity of classification air is 5 m/s.

Description

Die vorliegende Erfindung bezieht sich auf den Herstellungsprozeß von Toner einer bestimmten Kornverteilung für die Entwicklung elektrostatisch erzeugter Bilder, insbesondere auf ein Sichtverfahren zur Einstellung der erforderlichen Komverteilung als Mittel zur Erzielung hervorragender Qualität des Tonerprodukts.The present invention relates to the manufacturing process of a toner certain grain distribution for the development of electrostatically generated images, in particular on a visual procedure to set the required Grain distribution as a means of achieving excellent quality of the toner product.

Die Herstellung von Toner nach dem Stand der Technik umfaßt das Mischen geeigneter Komponenten, das Extrudieren, das Abkühlen und das nachfolgende Zerkleinern. Das zerkleinerte Material wird danach einer Sichtung zugeführt um unerwünschte Partikelfraktionen zu entfernen und ein Produkt mit der erwünschten Partikelgrößenverteilung zu erhalten. Die Partikelgrößenverteilung (PGV) wird normalerweise auf einem Coulter Counter Multisizer von Coulter Electronics, Inc. (USA) gemessen und ist eine Anzahlverteilung. Ziel der Sichtung ist zumeist ein Abtrennen sehr feiner Partikel im Bereich unter 5 µm, manchmal aber auch eine Oberkornbegrenzung oder beides zusammen.The manufacture of prior art toner involves blending suitable components, extruding, cooling and the subsequent Crushing. The shredded material is then subjected to a screening remove unwanted particle fractions and create a product with the desired Obtain particle size distribution. The particle size distribution (PGV) is usually on a Coulter Counter Multisizer from Coulter Electronics, Inc. (USA) measured and is a number distribution. The aim of the sighting is usually a Separation of very fine particles in the range below 5 µm, but sometimes also one Upper grain limit or both together.

Herkömmliche Prozesse benutzen zu diesem Zweck Sichter, wie sie z.B. aus der DE 39 15 641 A1 bekannt sind. Bei einem solchen Sichter, in dem keine gerichtete Produktführung vorliegt, kann sich das schon gesichtete Produkt wieder mit dem Aufgabegut vermischen. Es kommt dabei zu einer Kontamination des Produktes mit unerwünschtem Feingut, was den Erfolg der Sichtung beeinträchtigt. Diese Sichter verfügen zudem nicht über eine ausreichende Dispergierung des Aufgabegutes direkt vor der Sichtzone, so daß es zu Agglomeraten kommen kann, wodurch eigentlich zu feine Partikel in das Grobgut gelangen können. Durch diese Verschmutzung des Produktes mit feinen Partikeln kann es bei der Verwendung als Toner zu Qualitätseinbußen beim Druckbild kommen.Conventional processes use classifiers for this purpose, e.g. from the DE 39 15 641 A1 are known. With such a sifter in which there is no judged Product management is available, the already viewed product can be used again with the Mix feed material. This leads to contamination of the product with unwanted fines, which affects the success of the sighting. This Sifters also do not have sufficient dispersion of the Feed material directly in front of the viewing zone so that agglomerates can occur whereby actually too fine particles can get into the coarse material. Through this Contamination of the product with fine particles can occur when using it As a toner, the quality of the printed image is reduced.

Aufgabe der Erfindung ist die Bereitstellung eines Prozesses zur Herstellung von Toner, der die oben beschriebenen Probleme löst und es ermöglicht, einen Toner mit einer geforderten, engen Partikelgrößenverteilung möglichst effektiv herzustellen. Eine weitere Aufgabe ist die Bereitstellung eines Prozesses, der es ermöglicht den Feinanteil des Produktes zu reduzieren. Desweiteren geht es um einen Prozeß, bei dem sowohl der Feinanteil reduziert als auch das Oberkorn begrenzt werden kann, womit eine enge Partikelgrößenverteilung durch Sichtung mit einer gerichteten Materialführung erreicht wird, wobei das Ausgangsmaterial der Sichtung durch Mischen, Extrudieren und Zerkleinern einer Grundmischung erhalten wurde.The object of the invention is to provide a process for producing Toner that solves the problems described above and enables a toner with a required, narrow particle size distribution as effectively as possible manufacture. Another task is to provide a process for it enables the fine fraction of the product to be reduced. Furthermore, it is about a process in which both the fine fraction and the top grain are reduced can be limited, whereby a narrow particle size distribution by sighting is achieved with a directed material guide, the starting material the screening by mixing, extruding and crushing a basic mixture was obtained.

Die Aufgabe der Erfindung wird dadurch gelöst, daß durch eine Streuscheibe eine gleichmäßige Verteilung des Tonerproduktes über den Umfang des Sichterrades erreicht wird, das Tonerprodukt in einer gerichteten Materialführung in Richtung der Schwerkraft durch die Sichtzone geführt wird und zur Steuerung der Verweilzeit des Tonerproduktes Mittel in der Sichtzone vorgesehen sind, die im oberen Bereich der Sichtzone das Tonerprodukt im homogenen Zustand schnell in die Sichtzone einbringen, die im mittleren Bereich der Sichtzone das Tonerprodukt länger verweilen lassen und im anschließenden unteren Bereich der Sichtzone einen zügigen Abtransport des Tonerproduktes aus der Sichtzone ermöglichen.The object of the invention is achieved in that a even distribution of the toner product over the circumference of the classifier wheel is achieved, the toner product in a directional material guide in the direction of Gravity is guided through the viewing zone and to control the dwell time of the toner product means are provided in the viewing zone, in the upper area the toner product in the homogeneous state quickly into the viewing zone bring the toner product in the middle of the field of view longer let it linger and one in the lower area of the visual zone enable rapid removal of the toner product from the viewing zone.

Das Aufgabematerial, von dem Zerkleinerungsprozeß kommend, wird einer oder mehrerer Sichtungen unterzogen, je nachdem ob nur eine Entstaubung oder eine kombinierte Entstaubung / Oberkornbegrenzung gefordert wird. Bei alleiniger Entstaubung erhält man so eine Grobfraktion, die das Produkt darstellt und eine Feinfraktion, die wiederverwertet werden kann. Bei einer kombinierten Entstaubung / Oberkornbegrenzung erhält man eine Feinfraktion, eine Grobfraktion und eine Mittelfraktion, die das Produkt darstellt. Die beiden anderen Fraktionen werden entweder dem Extrudieren oder der Zerkleinerung wieder zugeführt. Bei der Sichtung ist auf eine gleichmäßige Verteilung des Aufgabematerials, eine gerichtete Materialführung während der Sichtung, eine Kontrolle der Verweilzeit und einen zügigen Abtransport des Grobgutes zu achten, um eine scharfe Sichtung zu gewährleisten und eine Kontamination des Sichtgutes zu verhindern.The feed material coming from the crushing process becomes one or subjected to several sightings, depending on whether only one dedusting or one combined dedusting / upper grain limitation is required. With sole Dedusting is obtained as a coarse fraction that represents the product and one Fine fraction that can be recycled. With a combined Dedusting / upper grain limitation gives you a fine fraction, a coarse fraction and a middle fraction representing the product. The other two factions are either fed back to extrusion or comminution. at the sighting is based on an even distribution of the feed material directed material guidance during the screening, a control of the dwell time and to ensure that the coarse goods are removed quickly in order to ensure a clear sighting to ensure and prevent contamination of the visible material.

Zur Erhöhung der zu sichtenden Produktmenge wird eine mehrfache Sichtung ausgeführt. Dabei wird das Grobgut der vorausgegangenen Sichtung erneut einem Sichter aufgegeben und nachgesichtet. Das Feingut kann von jeder Sichtstufe in einem gemeinsamen Filter gesammelt werden. Der Vorteil dieses Vorgehens liegt darin, daß die Beladung weit über den sonst üblichen Bereich von 0,05 bis 0,3 kg/m3 liegen kann. To increase the amount of product to be sifted, multiple sifting is carried out. The coarse material from the previous sifting is again given to a sifter and checked. The fine material can be collected from each view level in a common filter. The advantage of this procedure is that the loading can be far beyond the otherwise usual range of 0.05 to 0.3 kg / m 3 .

Eine Abschätzung der Gesamtbeladung erfolgt gemäß der Formel: µges = µ1 x na   mit   1 < a < 1,6 The total load is estimated according to the formula: μ ges = µ 1 xn a with 1 <a <1.6

Vorzugsweise wird für a der Wert 1,3 gewählt. Damit ergibt sich bei dreifacher Sichtung eine mögliche Beladung von 0,2 bis 0,83. Selbstverständlich ist auch eine mehrfache Sichtung im Bereich von a < 1 möglich. Dadurch wird die Produktqualität bei maximalem Grobgutanfall optimiert.The value 1.3 is preferably chosen for a. This results in triple Sighting a possible loading from 0.2 to 0.83. Of course there is also one multiple sightings in the range of a <1 possible. This will make the product quality optimized for maximum coarse material.

Erfindungsgemäß kommt ein vertikalachsiger Windsichter zur Anwendung, der eine zentrale Gutaufgabe mit tangentialer, in Höhe des Sichterrotors angeordneter Sichtluftzufuhr, einen feststehenden am Umfang des Sichterrotors in radialem Abstand angeordneten Leitschaufelkranz, einen ringförmigen, durch einen einseitig gelagerten Schaufelrad-Sichterrotor und einem koaxial in radialem Abstand zum Außenumfang des Sichterrotors angeordneten Leitschaufelkranz begrenzten Sichtraum, eine Antriebswelle für den einseitig gelagerten Sichterrotor sowie ein Gehäuse mit Feingut- und Grobgutaustritt aufweist.According to the invention, a vertical-axis air classifier is used, the one central feed with tangential, arranged at the level of the classifier rotor Visual air supply, a fixed one on the circumference of the classifying rotor in radial Spacer vane ring, an annular one through one mounted paddle wheel classifier rotor and a coaxial at a radial distance from The outer circumference of the classifying rotor arranged guide vane ring limited Visual space, a drive shaft for the classifier rotor mounted on one side and a Has housing with fine and coarse material outlet.

Das zu sichtende Gut wird zentral aufgegeben und von einem Streuteller flächig verteilt und über den Außenumfang des Sichterrotors glockenförmig als gleichmäßig verteilter Gutschleier an den Sichterrad-Schaufeln vorbei geführt. Das Sichterrad wird von der Sichtluft von außen nach innen durchströmt und das Feingut in das Innere des Sichterrotors geleitet. Das abgewiesene Grobgut folgt weiter der Schwerkraft und wird von einem ringförmigen Grobgutaustragsraum aufgenommen.The material to be sifted is fed in centrally and spread over a spreading plate distributed and bell-shaped over the outer circumference of the classifying rotor evenly distributed good veil passed past the classifier wheel blades. The The classifying wheel is flowed through by the classifying air from the outside in and that Fine material directed into the interior of the classifier rotor. The rejected coarse material follows gravity continues and is surrounded by an annular coarse material discharge area added.

Die Sichtzone ist von der Sichtluft radial von außen nach innen durchströmt. Durch das rotierende Schaufelrad wird das Grobgut radial nach außen abgewiesen und das Feingut zusammen mit der Sichtluft in das Innere des Sichterrotors transportiert. Das gesichtete Feingut wird sodann in eine axial nach unten führende Richtung umgelenkt und anschließend aus dem Sichterrotor durch die durchbrochene Antriebswelle hindurch ausgetragen.The visible air flows radially from the outside to the inside. By the rotating paddle wheel rejects the coarse material radially outwards and the fine material together with the classifying air into the interior of the classifying rotor transported. The fine material sighted is then led axially downward Redirected direction and then out of the classifier rotor through the broken through drive shaft.

Bei diesem vertikalachsigen Windsichter sind sowohl die mit Durchbrüchen versehene Antriebswelle, der ringförmige zur Antriebswelle koaxial angeordnete Feingutaustragsraum, als auch der ringförmige zur Antriebswelle koaxial angeordnete Grobgutaustragsraum, sowie die Sichterradlagerung auf der selben Seite und unterhalb des Sichterrotors angeordnet.

  • Fig.1 zeigt den verwendeten vertikalachsigen Windsichter.
  • Fig.2 zeigt eine Bauvariante des vertikalachsigen Windsichters.
  • Fig.3 zeigt einen Sichtprozeß für das Entstauben.
  • Fig.4 zeigt einen Sichtprozeß für eine kombinierte Grob- und Feinsichtung.
    • In this vertical-axis air classifier, both the drive shaft provided with openings, the annular fine material discharge space arranged coaxially with the drive shaft, and the annular coarse material discharge space arranged coaxially with the drive shaft, as well as the classifier wheel bearing, are arranged on the same side and below the classifier rotor.
  • Fig. 1 shows the vertical-axis air classifier used.
  • Fig. 2 shows a construction variant of the vertical-axis air classifier.
  • 3 shows a visual process for dedusting.
  • Fig. 4 shows a vision process for a combined rough and fine vision.

    • Bei einem Sichter gemäß Fig. 1 ist der den Feingutaustragsraum durchdringende Abschnitt der Antriebswelle 2 als durchbrochenes Wellenteil, der Stützeinrichtung 10, ausgebildet und ermöglicht dadurch den Durchtritt des Feingutes aus dem Inneren des Sichterrades 8 in den Feingutaustragsraum 14. 1, the section of the drive shaft 2 penetrating the fine material discharge space is designed as a perforated shaft part, the support device 10, and thereby enables the fine material to pass from inside the classifier wheel 8 into the fine material discharge space 14.

    Diese Stützeinrichtung 10 umfaßt dabei die Bodenscheibe 18, die Ringscheibe 17, sowie die strömungsgünstigen Distanzstege 10a und bilden ein Verbindungsglied zwischen Antriebswelle 2 und Sichterrad 8 und die Durchtritte für den Austrag des Feingutes aus dem Inneren des Sichterrades 8. This support device 10 comprises the base plate 18, the washer 17, and the aerodynamic spacer webs 10a and form a connecting link between the drive shaft 2 and classifier wheel 8 and the passages for the discharge of the fine material from the inside of classifier wheel 8.

    Das Sichterrad 8 besteht aus dem Sichterradschaufelkranz 9, der Streuscheibe 16 und der Deckscheibe 15 und ist mit der Stützeinrichtung 10 drehfest verbunden. Diese Verbindung im Bereich der Scheiben 15 und 17 kann lösbar gestaltet sein und z. B. durch gleichmäßig über den Umfang des Sichterrotors angeordnete Schrauben 19 erfolgen.The classifier wheel 8 consists of the classifier wheel vane ring 9, the lens 16 and the cover plate 15 and is rotatably connected to the support device 10 . This connection in the area of the discs 15 and 17 can be designed releasably and z. B. by screws 19 arranged uniformly over the circumference of the classifying rotor.

    Im Bereich der Scheiben 15,17 und dem Gehäuse 1 ist eine mit einem Fluid spülbare Dichtung 20 in axialer Anordnung dargestellt und trennt zuverlässig den Sichtraum 21 von dem Feingutaustrittsraum 14. In the area of the disks 15, 17 and the housing 1 , a seal 20 that can be flushed with a fluid is shown in an axial arrangement and reliably separates the visible space 21 from the fine material outlet space 14.

    Im axialen Übergangsbereich zwischen Sichterrad 8 und Stützeinrichtung 10 ragt die untere Deckscheibe 15 über den Innendurchmesser der Ringscheibe 17, und damit über die Stützeinrichtung 10 in den Innenraum hinein und bildet somit im Übergangsbereich eine Blende mit Drosselwirkung. In the axial transition area between classifier wheel 8 and support device 10 , the lower cover disk 15 projects beyond the inner diameter of the annular disk 17, and thus over the support device 10 into the interior , and thus forms an orifice with a throttling effect in the transition area.

    Die Gutaufgabe erfolgt auf die Deckscheibe 16 des Sichterrades 8, die eine Streuscheibe bildet. Der Ringkanal zwischen dem Außendurchmesser des Sichterrades 8 und dem Innendurchmesser des Leitschaufelkranzes 13 bildet über die Höhe des Sichterrades 8 den Sichtraum 21. The goods are placed on the cover plate 16 of the classifying wheel 8, which forms a diffusing plate. The annular channel between the outer diameter of the classifying wheel 8 and the inner diameter of the guide vane ring 13 forms the classifying space 21 over the height of the classifying wheel 8 .

    Der Sichtraum 21 wird vom Sichtgut in vertikaler Richtung durchströmt. Zur Steuerung sowohl der Sichtgutkonzentration im Sichtraum 21, als auch der Verweilzeit erstreckt sich eine Schneckenwendel 29 nahezu über die gesamte radiale Breite des Sichtraumes 21 und verläuft über die gesamte Höhe des Sichterrades 8 hinweg. In der dargestellten Ausbildung findet eine einzelne Schneckenwendel mit konstanter Steigung Anwendung.The visible material 21 flows through the visible space 21 in the vertical direction. In order to control both the concentration of visible material in the visible space 21 and the dwell time, a screw spiral 29 extends almost over the entire radial width of the visible space 21 and extends over the entire height of the classifying wheel 8 . In the embodiment shown, a single helical screw with a constant pitch is used.

    Senkrecht zum Sichtgutstrom verläuft die Sichtluftströmung. Die Sichtluft gelangt dabei vom Sichtlufteintritt 22 horizontal durch den feststehenden Leitschaufelkranz 3 in den Sichterraum 21 und durchströmt ihn senkrecht zum Sichtgutstrom.The sifting air flow runs perpendicular to the sifting material flow. The classifying air from the classifying air inlet 22 passes horizontally through the fixed guide vane ring 3 into the classifying chamber 21 and flows through it perpendicularly to the classifying material flow.

    Über den Feingutaustritt 23 wird das gesichtete Feingut mit der Sichtluft axial ausgetragen. Das gesichtete Grobgut wird durch den Grobgutaustragsraum 13 unterhalb des Sichtraumes 21 über den Grobgutaustritt 24 ausgetragen.The fine material sighted is discharged axially with the classifying air via the fine material outlet 23 . The coarse material sighted is discharged through the coarse material discharge space 13 below the viewing space 21 via the coarse material outlet 24 .

    Der Grobgut-Austragsring 25 ist fest mit dem Sichterrad 8 verbunden und rotiert innerhalb des Grobgutaustragsraumes 13. Oberhalb des Grobgutaustragsraumes 13 ist der feststehende Rückhaltering 26 angeordnet und mit dem Gehäuse 1 fest verbunden.The coarse material discharge ring 25 is fixedly connected to the classifying wheel 8 and rotates within the coarse material discharge space 13. The fixed retaining ring 26 is arranged above the coarse material discharge space 13 and is fixedly connected to the housing 1 .

    Zwischen dem Boden des Grobgutaustragsraumes 13 und dem Grobgut-Austragsring 25 befindet sich der Spalt 27 für die Einleitung der Spülluft 28. The gap 27 for the introduction of the scavenging air 28 is located between the bottom of the coarse material discharge space 13 and the coarse material discharge ring 25 .

    Gemäß Fig. 2 ist die Antriebswelle oberhalb des Sichtrades angeordnet und durchdringt den Produktzuführbereich. Die Materialaufgabe erfolgt zentral von oben durch die ringförmige Aufgabeöffnung 220 auf das Sichtrad 221. Das Material wird nach außen gegen den Prallring 222 geschleudert und so gleichmäßig auf dem Umfang verteilt. Es fällt dann in den Sichtspalt zwischen Schaufelkranz 223 und Sichtrad 221, wo es von der Sichtluft durchspült wird. Die Sichtluft tritt durch das Spiralgehäuse 224 in den Sichtraum, strömt durch das Sichtrad 221 und verläßt den Sichter zusammen mit dem Feingut nach unten in Richtung der Schwerkraft durch den Feingutaustritt 225. Der Schaufelkranz 223 ist mit einer oder mehreren Schneckenwendeln 226 ausgerüstet, um die Verweilzeit des Materials zu steuern. Für verschiedene Sichtaufgaben, z. B. Grob- oder Feinsichtung können auch unterschiedliche Schaufelkränze zur Anwendung kommen.2, the drive shaft is arranged above the classifying wheel and penetrates the product feed area. The material is fed in centrally from above through the ring-shaped feed opening 220 onto the classifying wheel 221. The material is thrown outwards against the impact ring 222 and is thus distributed evenly over the circumference. It then falls into the viewing gap between the blade ring 223 and the classifying wheel 221, where it is flushed by the classifying air. The classifying air enters the classifying chamber through the spiral housing 224 , flows through the classifying wheel 221 and leaves the classifier together with the fine material downward in the direction of gravity through the fine material outlet 225. The blade ring 223 is equipped with one or more screw spirals 226 in order to increase the dwell time to control the material. For various visual tasks, e.g. B. Coarse or fine sighting, different blade rings can also be used.

    Ein erfindungsgemäßer Sichtprozeß für das Entstauben, der den oben beschriebenen Sichtertyp beinhaltet, ist in Fig. 3 dargestellt. Die Aufgabe erfolgt dabei von oben durch ein geeignetes Dosierorgan 301. Das Verhältnis von Sichtluftvolumenstrom zu Aufgabemassenstrom sollte im Bereich von 0,05 kg/m3 bis 0,3 kg /m3, vorzugsweise bei 0,1 kg/m3 liegen. Die Sichtluft tritt durch den Sichtlufteintritt 304 in den Sichter 306 ein und wird mittels eines Gebläses 309 durch den Sichter 306 in einen optionalen Zyklon 307 und einen Filter 308 gesaugt. Das Gebläse 309 wird so eingestellt, daß an der Außenkante des Sichtrades Luftgeschwindigkeiten im Bereich von 3 m/s bis 7 m/s vorliegen.A screening process according to the invention for dedusting, which includes the screen type described above, is shown in FIG. 3. The task is carried out from above by a suitable metering element 301. The ratio of sifting air volume flow to feed mass flow should be in the range from 0.05 kg / m 3 to 0.3 kg / m 3 , preferably 0.1 kg / m 3 . The classifying air enters classifier 306 through classifying air inlet 304 and is drawn in by fan 309 through classifier 306 into an optional cyclone 307 and filter 308 . The blower 309 is adjusted so that air velocities in the range of 3 m / s to 7 m / s are present on the outer edge of the classifying wheel.

    Die Umfangsgeschwindigkeiten des Sichtrades bei einer Feinsichtung liegen zwischen 40 m/s und 65 m/s, bei einer Grobsichtung liegen sie vorzugsweise im Bereich von 20 m/s bis 45 m/s. Der hier genannte Prozeß kann entweder mit einem nachgeschaltetem Zyklon 307 und einem Filter 308 oder nur mit einem Filter 308 betrieben werden. Über die Feingutleitung 318 wird das ausgesichtete Feingut zunächst dem Zyklon 307 zugeführt und der wesentliche Teil aus der Sichtluft abgetrennt und kann über den Feingutaustrag 303 ausgetragen werden. Ultrafeine Teilchen, die noch mit der Sichtluft mitgerissen wurden, setzen sich am Filter 308 ab und können nach Absprengung vom Filtermaterial über den Staubaustrag 305 abgeführt werden. Das fertige Produkt wird über den Grobgutaustrag 302 erhalten.The peripheral speeds of the classifying wheel for a fine sighting are between 40 m / s and 65 m / s, for a rough sighting they are preferably in the range of 20 m / s to 45 m / s. The process mentioned here can either be operated with a downstream cyclone 307 and a filter 308 or only with a filter 308 . The selected fine material is first fed to the cyclone 307 via the fine material line 318 and the essential part is separated from the classifying air and can be discharged via the fine material discharge 303 . Ultrafine particles that were still entrained with the visible air settle on the filter 308 and can be removed via the dust discharge 305 after being blasted off from the filter material. The finished product is obtained via the coarse material discharge 302 .

    Es bietet sich somit gemäß Fig. 3 die Möglichkeit einer einfachen Feinsichtung zum Staubabtrennen, wahlweise kann aber auch eine kombinierte Grobsichtung und Feinsichtung zur gleichzeitigen Entstaubung und Oberkornbegrenzung gemäß Fig. 4 durchgeführt werden. 3 there is thus the possibility of simple fine sighting Dust separation, but also a combined rough sighting and Fine screening for simultaneous dedusting and upper grain limitation according to FIG. 4 be performed.

    Fig. 4 zeigt ein solches Anlagenschema für eine kombinierte Grob- und Feinsichtung und eine zweifache Feinsichtung.Fig. 4 shows such a system scheme for a combined rough and Fine sighting and double fine sighting.

    Bei der kombinierten Grob- und Feinsichtung wird das Material zunächst einer Feinsichtung analog zu Fig. 3 unterzogen. Das weiterzuverarbeitende Produkt ist das Grobgut aus der ersten Sichtung und wird über die Leitung des ersten Grobgutaustrags 402 der Produktaufgabe des zweiten Sichters 410 zugeführt. In der zweiten Sichtung unterwirft man das Aufgabegut einer Grobsichtung, um das Oberkorn zu begrenzen, d.h. das in der zweiten Sichtung erhaltene Feingut aus dem Zyklon 411 und dem Filter 412 wird jeweils über den Feingutaustrag 416 und dem Staubaustrag 417 erhalten und stellt das eigentliche Produkt dar. Die sehr groben Anteile, deren Korndurchmesser über der gewünschten Oberkorngrenze liegen, werden über den Grobgutaustrag 415 ausgetragen und können verworfen oder z.B. einer erneuten Mahlung zugeführt werden.In the case of the combined rough and fine screening, the material is first subjected to a fine screening analogous to FIG. 3. The product to be processed is the coarse material from the first screening and is fed to the product task of the second classifier 410 via the line of the first coarse material discharge 402 . In the second screening, the feed material is subjected to a rough screening in order to limit the top grain, i.e. the fine material obtained in the second screening from the cyclone 411 and the filter 412 is obtained via the fine material discharge 416 and the dust discharge 417 and represents the actual product The very coarse fractions, the grain diameter of which is above the desired upper grain limit, are discharged via the coarse material discharge 415 and can be discarded or, for example, re-ground.

    Durch die Anwendung von Feinsichtung und Grobsichtung in einer Anordnung erübrigt sich ein zwischenzeitliches Abscheiden des Produktes, da es aus dem Grobgutaustrag 402 direkt auf den zweiten Sichter 410 aufgegeben werden kann. Es besteht auch die Möglichkeit zuerst die Grobsichtung durchzuführen und nach Abscheidung des Materials und Aufgabe auf den zweiten Sichter, die Feinsichtung anzuschließen.By using fine sifting and rough sifting in an arrangement, there is no need to separate the product in the meantime since it can be fed directly onto the second sifter 410 from the coarse material discharge 402 . There is also the possibility to carry out the rough screening first and after separating the material and placing it on the second sifter, to connect the fine screening.

    Der Anlagenaufbau gemäß Fig. 4 kann in gleicher Weise für eine zweistufige Feinsichtung genutzt werden. Dabei wird jedoch nicht die Mittelfraktion aus dem Feingutaustrag 416 und dem Staubaustrag 417 als Produkt erhalten, sondern das Grobgut aus dem Grobgutaustrag 415 stellt das Produkt dar. Durch die geeignete Wahl der Sichtereinstellungen kann somit eine extreme Entstaubung des Produktes erreicht werden. Dieser Aufbau läßt sich auf eine mehrfache Feinsichtung erweitern, indem man weitere Stufen in analoger Weise hinzufügt.4 can be used in the same way for a two-stage fine sighting. However, it is not the middle fraction from the fine material discharge 416 and the dust discharge 417 that is obtained as the product, but the coarse material from the coarse material discharge 415 represents the product. The appropriate selection of the classifier settings can therefore achieve extreme dust removal from the product. This structure can be extended to multiple fine sightings by adding further stages in an analogous manner.

    In den Diagrammen 1 und 2 sind die Partikelgrößen-Verteilungskurven, gemessen mit einem Coulter Counter Multisizer von Coulter Electronics, Inc. (USA) dargestellt. Das Ziel war eine Entstaubung durch möglichst vollständige Abtrennung der Feinanteile unterhalb von 5 µm. The particle size distribution curves are measured in diagrams 1 and 2 with a Coulter Counter Multisizer from Coulter Electronics, Inc. (USA). The goal was to remove dust by separating the Fine particles below 5 µm.

    Das Ausgangsmaterial weist einen sehr hohen Feingutanteil auf und stellt somit einen Toner minderer Qualität dar. Diagramm 1 zeigt die Produktverbesserung wie sie durch eine erfindungsgemäße zweistufige Feinsichtung gemäß Fig. 4 erreicht wird. Deutlich ist zu erkennen, daß bereits die erste Sichtung den weit überwiegenden Anteil von Feinststauben unter 5 µm abtrennen kann. Durch die folgende zweite Feinsichtung wird der Anteil von Feinststauben nochmals um ca. 50% reduziert. Das fertig gesichtete Produkt weist eine sehr hohe Steilheit knapp über der Trenngrenze von 5µm auf. Durch das erfindungsgemäße Verfahren wird somit eine sehr scharfe Trennung erzielt.The starting material has a very high proportion of fine material and thus represents a low quality toner. Diagram 1 shows the product improvement as it is achieved by a two-stage fine sighting according to the invention according to FIG. 4 becomes. It can be clearly seen that the first sighting is far can remove most of the fine dust below 5 µm. Through the following the second fine screening, the proportion of fine dust is increased again by approx. 50% reduced. The finished sighted product shows a very high slope above the separation limit of 5µm. By the method according to the invention thus achieved a very sharp separation.

    In Diagramm 2 sind die Partikelgrößen-Verteilungskurven einer erfindungsgemäßen Sichtung mit gesteuerter Verweilzeit des Sichtgutes einer Sichtung ohne einer derartigen Steuerung bei Verwendung des gleichen Sichtertyps und gleicher Sichtereinstellungen gegenübergestellt. Durch die Steuerung der Verweilzeit des Sichtgutes in der Sichtzone kann, bei ansonsten gleichen Sichtbedingungen, wesentlich mehr Feinststaub aus dem Sichtgut abgetrennt werden.In Diagram 2, the particle size distribution curves are one sighting according to the invention with a controlled dwell time of the material to be sighted Sighting without such control using the same Sifter types and the same sifter settings are compared. Through the Control of the dwell time of the material to be viewed in the viewing zone can, otherwise same visibility conditions, much more fine dust from the sight be separated.

    Claims (6)

    1. Air classification process for toner used to develop electrostatic images, whereby a toner product consisting of a powder with a wide particle size distribution is converted into a higher-quality toner product with a narrow particle size distribution, characterised in that:
      a uniform distribution of the toner product across the extent of the classifying wheel is achieved by means of a centrifugal plate,
      the toner product is routed by means of a controlled material feed section in gravitational direction through the classifying zone,
      components are installed in the classifying zone to permit controlling the residence time of the toner product, components which in the upper section of the classifying zone quickly introduce the toner product in a homogeneous state into the classifying zone, which in the central section of the classifying zone permit a longer residence time of the toner product, and which in the bottom section of the classifying zone permit rapid discharge of the toner product from the classifying zone,
      whereby the classifying air with an average flow rate of between 3 and 7 m/s is routed past the outer edge of the classifying wheel and the toner product mass flow rate is kept at a ratio to the classifying air volume flow rate of between 0.05 kg/m3 and 0.3 kg/m3.
    2. Process as per Claim 1, characterised in that the component selected to control the residence time is a screw-shaped helix which spirals coaxially around the classifying wheel within the classifying zone.
    3. Process as per Claim 2, characterised in that the helix is located only in a partial area of the radial extent of the classifying zone.
    4. Process as per Claim 2 or 3, characterised in that the pitch of the helix varies along its length.
    5. Process as per Claims 1 - 4, characterised in that the preferred ratio of toner product mass flow rate to classifying air volume flow rate is 0.1 kg/m3.
    6. Process as per Claims 1 - 5, characterised in that the preferred average flow rate of the classifying air is 5 m/s.
    EP99100551A 1998-01-28 1999-01-13 Method for the pneumatic classification of toner Expired - Lifetime EP0933142B1 (en)

    Applications Claiming Priority (2)

    Application Number Priority Date Filing Date Title
    DE19803107A DE19803107A1 (en) 1998-01-28 1998-01-28 Process for air separation of toner
    DE19803107 1998-01-28

    Publications (3)

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    EP0933142A2 EP0933142A2 (en) 1999-08-04
    EP0933142A3 EP0933142A3 (en) 2000-07-19
    EP0933142B1 true EP0933142B1 (en) 2002-06-05

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    EP (1) EP0933142B1 (en)
    JP (1) JPH11288133A (en)
    AT (1) ATE218399T1 (en)
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    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    DE10007794A1 (en) 2000-02-21 2001-06-28 Zimmer Ag Composition useful for making containers, films, membranes and fibers, comprises a biodegradable polymer and a marine plant or shell material
    US6776291B1 (en) * 2000-09-27 2004-08-17 Xerox Corporation Article and apparatus for particulate size separation
    JP5078138B2 (en) * 2007-08-23 2012-11-21 アシザワ・ファインテック株式会社 Centrifugal classifier

    Family Cites Families (4)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    US4304360A (en) * 1979-12-31 1981-12-08 International Business Machines Corporation Xerograhic toner manufacture
    US5016823A (en) * 1989-05-12 1991-05-21 Canon Kabushiki Kaisha Air current classifier, process for preparing toner, and apparatus for preparing toner
    DE4014342C2 (en) * 1990-05-04 1994-06-23 Heinz Jaeger Air classifier
    ES2190796T3 (en) * 1996-10-18 2003-08-16 Hosokawa Alpine Ag & Co VERTICAL AXLE PNEUMATIC SEPARATOR.

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    JPH11288133A (en) 1999-10-19
    ATE218399T1 (en) 2002-06-15
    EP0933142A3 (en) 2000-07-19
    DE19803107A1 (en) 1999-07-29
    EP0933142A2 (en) 1999-08-04

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