EP1678452A1 - Veneer dryer - Google Patents

Veneer dryer

Info

Publication number
EP1678452A1
EP1678452A1 EP04741402A EP04741402A EP1678452A1 EP 1678452 A1 EP1678452 A1 EP 1678452A1 EP 04741402 A EP04741402 A EP 04741402A EP 04741402 A EP04741402 A EP 04741402A EP 1678452 A1 EP1678452 A1 EP 1678452A1
Authority
EP
European Patent Office
Prior art keywords
drying
dryer
veneers
conveyor belts
zones
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP04741402A
Other languages
German (de)
French (fr)
Inventor
Wilfried Möller
Gottfried Roos
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Grenzebach BSH GmbH
Original Assignee
Grenzebach BSH GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Grenzebach BSH GmbH filed Critical Grenzebach BSH GmbH
Publication of EP1678452A1 publication Critical patent/EP1678452A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26DRYING
    • F26BDRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B13/00Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26DRYING
    • F26BDRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B13/00Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement
    • F26B13/06Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement with movement in a sinuous or zig-zag path
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26DRYING
    • F26BDRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B13/00Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement
    • F26B13/10Arrangements for feeding, heating or supporting materials; Controlling movement, tension or position of materials
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26DRYING
    • F26BDRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B13/00Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement
    • F26B13/10Arrangements for feeding, heating or supporting materials; Controlling movement, tension or position of materials
    • F26B13/101Supporting materials without tension, e.g. on or between foraminous belts
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26DRYING
    • F26BDRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B2210/00Drying processes and machines for solid objects characterised by the specific requirements of the drying good
    • F26B2210/14Veneer, i.e. wood in thin sheets

Definitions

  • the invention relates to a dryer for sliced veneers according to the preamble of claim 1.
  • Sliced veneers tend to deform when drying due to different degrees of shrinkage.
  • the result is wavy veneers that may have cracks and / or pressure marks.
  • the veneers must be dried in several drying zones arranged one behind the other, each with optimally adjusted parameters such as temperature, humidity of the drying medium and effective pressure on the veneers.
  • the pressure acting on the veneers must be varied such that the wet veneers are initially exposed to low pressure and the dried veneers are smoothed using pressure. This is why a straight line of conveyor belts is followed by a so-called ironing section, in which the veneers are deflected in many ways and are thus exposed to increased pressure.
  • a dryer for sliced veneers is known from EP 192 207 B1, in which the veneers between two conveyor belts are first dried in a part with a straight guide and then in a part with a loop-like guide of the conveyor belts.
  • the dryer is subdivided into fields that can form drying zones individually or in combination with the required drying climate.
  • the fields are arranged one behind the other in a horizontal plane.
  • US Pat. No. 6,108,942 describes a dryer for sliced veneers, in which the guidance of two conveyor belts forms a straight and a curved drying path, each of the paths being able to be arranged in a plurality of horizontal planes to be traversed one behind the other. Drying zones can be arranged one behind the other in a horizontal plane.
  • the known dryers for sliced veneers have the disadvantage that the individual drying zones cannot be clearly separated. This lack of separability is particularly critical when exhaust air is introduced from, for example, a first drying zone into a second. A backflow of drying medium from the second into the first drying zone can always be observed, that is to say a mixing of the drying parameters. Practice has shown that temperature differences of up to 30 ° C can be maintained between the individual drying zones; a desired moisture content of the drying medium can be correspondingly inaccurate and adjust the veneers in the individual zones of the dryer. This leads to the fact that the veneers are not of optimal quality and, for example, show pressure marks due to the bands, cracks and / or waviness.
  • deflection or deflection means that the conveyor belts are guided after the deflection in such a way that the general direction of transport, i.e. without taking into account loop and / or wave-shaped guidance, comes from one end of the dryer by approximately 180 ° to the same end changes.
  • the transport levels are parallel or almost parallel.
  • the object of the invention is to provide a dryer for sliced veneers, in which the drying parameters can be selectively adjusted over wide areas in the drying zones and thus veneers with optimal quality can be produced.
  • the object is achieved by the characterizing features of claim 1.
  • the arrangement of the drying zones on top of one another in horizontal planes prevents significant amounts of drying medium from passing from one drying zone into an adjacent drying zone without additional sealing effort. This means that an optimal drying climate can be set in each individual drying zone depending on the type of wood, without influencing the adjacent drying zones.
  • the conveyor belts are redirected at least during the transition from one of the drying zones to the next one, so that the general direction of transport changes during the transition from one to the next drying zone.
  • the conveyor belts are shorter overall than when the drying zones are arranged on one level, because the return to the dryer entrance takes place over a considerably shorter distance. Another advantage is that the drying zones arranged one above the other save space for the installation of the dryer.
  • the spatial separation of the deflection rollers, which are arranged in the transition from one of the drying zones to the next, from the drying zones according to claim 2 enables an even better partitioning between the drying zones and a simpler construction of the deflection.
  • the additional deflection of the conveyor belts in one of the drying zones according to claim 3 extends the distance in this drying zone with comparatively little effort and thus increases the performance of the dryer.
  • the extension of the straight course of the conveyor belts to at least part of the second drying zone according to claim 4 means that a first deflection of the conveyor belts and thus an increased pressure on the veneers only takes place when the surfaces of the veneers have already largely dried. This reliably prevents the pattern of the conveyor belts from being pressed into the surfaces and thus being visible.
  • the subdivision of the conveyor belt according to claim 5 makes it possible to decouple the pressure acting on the veneers by the conveyor belts in the ironing section from the pressure in the rest of the dryer. The pressure in the ironing section can therefore be optimally adjusted.
  • Three drying zones according to claim 6 allow an optimal adaptation of the drying conditions to the needs.
  • the pretensioning of the conveyor belts can be low without them sagging inadmissibly. This further reduces the pressure on the veneers in this section.
  • a sensor according to claim 8, in conjunction with an evaluation and control device, allows the drying to be optimally adapted to different qualities of the veneers.
  • FIG. 9 shows a longitudinal section through a dryer
  • Figure 2 shows a cross section through a dryer along the line AB
  • Figure 3 shows a cross section through a dryer of another embodiment.
  • a housing 1 encloses a drying room which comprises three drying zones 2, 3, 4.
  • the drying zones 2, 3, 4 are arranged one above the other in horizontal planes and separated from one another by floors 11.
  • a dryer inlet 5 which is arranged at the bottom left according to FIG. 1
  • two endless conveyor belts 6 are guided parallel and at a short distance from one another or touching one after the other through the drying zones 2, 3, 4 to a dryer outlet 7 which is located at an opposite end of the dryer inlet 5
  • Side of the drying room is arranged.
  • the direction of transport is illustrated by arrows 8.
  • the lower conveyor belt 6 is guided so that it protrudes a short distance from the dryer.
  • the conveyor belts 6 are equipped with a controllable drive system and are returned individually from the dryer outlet 7 via rollers and a tensioning device to the dryer inlet 5.
  • the conveyor belts 6 are guided in the form of flat waves, that is to say approximately in a straight line in one plane.
  • support rollers 9 are arranged spaced apart in the transport direction, only a part of which is shown. The longitudinal axes of the support rollers 9 are aligned horizontally and perpendicularly to the transport direction.
  • the conveyor belts 6 are guided over the support rollers 9.
  • the conveyor belts 6 are deflected into the second drying zone 3 via three deflecting rollers 10 in such a way that the general direction of transport is changed by 180 °.
  • the lower boundary of the lower deflecting roller 10 and the upper boundary of the upper deflecting roller 10 are in an approximately central plane of the corresponding drying zone 2, 3.
  • the ironing section begins in the second half of the second drying zone 3.
  • a multiplicity of rollers 12 spaced apart in a horizontal plane are arranged, their longitudinal axes being aligned at right angles to the direction of transport.
  • the center distance of two of the rollers 12 corresponds approximately to three times the radius of one of the rollers 12.
  • the conveyor belts 6 are alternately guided in a loop above and below the rollers 12.
  • the conveyor belts 6 are guided from the last roller 12 below via a further deflecting roller 10 to a first of a plurality of rollers 13 of the third drying stage 4 and are thus deflected by 180 °.
  • the rollers 13 of the third drying stage 4 are arranged in a horizontal plane, the longitudinal axes being oriented at right angles to the direction of transport.
  • the rollers 13 have the same diameter as the rollers 12 of the second drying stage 3.
  • the center distance of the rollers 13 is approximately three times their radius.
  • Each drying zone 2, 3, 4 is assigned means for inflating drying medium onto the veneers.
  • the drying medium is usually air that is circulated.
  • the means for inflating comprise for each drying zone 2, 3, 4 at least one fan, here a radial fan 14 with a controllable drive, at least one heat exchanger 15 with a controllable supply of heating medium, a large number of nozzle boxes 16 in a known arrangement, of which only a part in FIG. 1 is shown, an exhaust air line 17 with control valve and various channels for collecting and distributing drying medium.
  • the radial fan 14 is fastened to a horizontal part of the housing 1 with a vertical drive axis.
  • a sensor 18 for determining the moisture of the undried veneers is arranged in an area in front of the dryer inlet 5.
  • the sensor 18 is connected to a corresponding evaluation unit.
  • a drying device for sliced veneers includes devices, not shown, such as a feed device which transfers the veneers to the lower conveyor belt 6 at the transfer point, a cooler for the veneers and a discharge device.
  • the ironing section is always in the second drying zone 3, while the rectilinear part of the conveyor belts 6 is arranged in the first drying zone 2 and possibly in a part of the second drying zone 3.
  • the conveyor belts 6 can be deflected by 180 ° within one or more of the drying zones 2, 3, 4 in order to extend the transport distance and thus the time of stay of the veneers within the corresponding drying zone 2, 3, 4.
  • the deflection of the conveyor belts 6 into the next drying zone 3, 4 or the discharge of the veneers then takes place on the same side of the drying room as the entry into the corresponding drying zone 2, 3, 4.
  • each deflection of the conveyor belts 6 from one drying zone 2, 3 into the next one can be arranged outside the corresponding drying zones 2, 3, 4.
  • the deflections are separated from drying zones 2, 3, 4 by, for example, metal sheets.
  • the conveyor belt 6, which is arranged at the top in the ironing section is divided into two.
  • the upper conveyor belt 6 in the ironing section is designed such that it exerts a higher pressure on the veneers than in the rest of the dryer. This can be achieved, for example, by a higher pretension and / or a particularly large basis weight of this conveyor belt 6.
  • FIG. 3 differs in the following features from the example according to FIGS. 1 and 2:
  • the radial fans 14 are arranged with a horizontal axis of rotation and all on only one side of the housing 1.
  • the housing 1 can be cuboid-shaped for the entire dryer, without indentations and / or bulges.
  • the veneers which are cut in sheet form from a block of wood with a thickness of, for example, 0.2 to 4.0 mm, are placed on the lower conveyor belt 6 at this point by the feed device shortly before the dryer inlet 5.
  • the veneers lie largely flat on the conveyor belt 6.
  • their moisture ie the amount of water per amount of dry wood, is measured.
  • the veneers are covered by the upper conveyor belt 6 and pressed flat against the lower conveyor belt 6 due to its own weight.
  • An exhaust air guide that is, the introduction of drying air before heating in the heat exchangers 15 from one of the drying zones 2, 3, 4 into another, takes place via flaps 19 in the trays 1 into one or the next Drying zones 3, 4, in order to increase the (absolute) humidity of the air and thus to allow the setting of higher drying air temperatures.
  • the veneers are guided essentially in a straight line, the slight wave movement resulting from the support by the support rollers 9. This guiding means that the veneers are only exposed to a slight pressure that does not damage their surfaces.
  • the temperature and humidity of the drying air are set so that the surfaces of the veneers are largely dried. This prevents discolouration and the so-called cladding (shrinking of the surface, which is hampered by the still damp interior and thus leads to tension and cracks in the surface) of the veneers.
  • the veneers are directed upwards into the second drying zone 3, the general direction of transport changing by 180 °.
  • the veneers are first guided in a substantially straight line and then in a loop around the rollers 12.
  • the veneers run between the rollers 12 in a straight line, the length of which corresponds at least to the diameter of the rollers 12.
  • the temperature and humidity of the drying air are set so that the moisture of the veneers at the beginning of the ironing section, that is to say approximately in the middle of the second drying zone 3, is at least 30%.
  • the veneers are guided upwards into the third drying zone 4, the direction of transport again changing by 180 °.
  • the ironing section continues with the loop-shaped guide.
  • the temperature and humidity of the drying air are set so that lignin bridges in the wood are plasticized on the one hand and elastic veneers are obtained and on the other hand the desired final moisture content of the veneers is achieved.
  • the temperature and humidity vary from drying zone to drying zone and depend on the type of wood, the initial moisture of the veneers and the amount of veneers.
  • the speed of the conveyor belts, the speed of the fans, the amount of heating medium as well as the amount of exhaust air and the exhaust air routing are regulated accordingly. Automation means are provided for this.
  • the veneers After drying, the veneers are cooled and stacked in the known manner.

Abstract

The problem with known veneer dryers is that the individual drying zones cannot be separated distinctly. The optimal process conditions, which change during the drying process, cannot therefore be adjusted as required, as this leads to short-circuit currents between the drying zones. The aim of the invention is to provide a veneer dryer, in which the drying parameters can be optimally adjusted zone by zone. To achieve this, the drying zones (2, 3, 4) are arranged one above the other on horizontal planes and are thus effectively separated from one another. The inventive dryer is used for the production of veneers.

Description

Furniertrockner veneer dryer
Die Erfindung betrifft einen Trockner für Messerfurniere gemäß dem Oberbegriff des Anspruchs 1.The invention relates to a dryer for sliced veneers according to the preamble of claim 1.
Messerfurniere neigen beim Trocknen dazu, sich wegen unterschiedlicher Schrump- fungsgrade zu verformen. Die Folge sind wellige Furniere, die Risse und/oder Druckstellen aufweisen können. Damit diese Mängel nicht auftreten, müssen die Furniere in mehreren hintereinander angeordneten Trocknungszonen mit jeweils optimal ange- passten Parametern, wie Temperatur, Feuchte des Trocknungsmediums und wirksamer Druck auf die Furniere, getrocknet werden. Weiterhin muss der auf die Furniere wirksame Druck derart variiert werden, dass die nassen Furniere zunächst geringem Druck ausgesetzt sind und die angetrockneten Furniere mit Hilfe von Druck geglättet werden. Deshalb schließt sich an eine geradlinige Führung von Transportbändern eine sogenannte Bügelstrecke an, in der die Furniere vielfach umgelenkt und so einem erhöhten Druck ausgesetzt werden. Aus der EP 192 207 B1 ist ein Trockner für Messerfurniere bekannt, bei dem die Furniere zwischen zwei Transportbändern zunächst in einem Teil mit geradliniger Führung und anschließend in einem Teil mit schleifenförmiger Führung der Transportbänder getrocknet werden. Der Trockner ist in Felder unterteilt, die einzeln oder mehrere zu- sammengefasst Trocknungszonen mit dem erforderlichen Trockenklima bilden können. Die Felder sind in einer horizontalen Ebene hintereinander angeordnet.Sliced veneers tend to deform when drying due to different degrees of shrinkage. The result is wavy veneers that may have cracks and / or pressure marks. To prevent these defects from occurring, the veneers must be dried in several drying zones arranged one behind the other, each with optimally adjusted parameters such as temperature, humidity of the drying medium and effective pressure on the veneers. Furthermore, the pressure acting on the veneers must be varied such that the wet veneers are initially exposed to low pressure and the dried veneers are smoothed using pressure. This is why a straight line of conveyor belts is followed by a so-called ironing section, in which the veneers are deflected in many ways and are thus exposed to increased pressure. A dryer for sliced veneers is known from EP 192 207 B1, in which the veneers between two conveyor belts are first dried in a part with a straight guide and then in a part with a loop-like guide of the conveyor belts. The dryer is subdivided into fields that can form drying zones individually or in combination with the required drying climate. The fields are arranged one behind the other in a horizontal plane.
Die US 6,108 942 beschreibt einen Trockner für Messerfurniere, bei dem die Führung zweier Transportbänder einen geradlinig verlaufenden und einen kurvigen Trocknungsweg bildet, wobei jeder der Wege in mehreren horizontalen, hintereinander zu durchlaufenden Ebenen angeordnet sein kann. Trocknungszonen können in einer horizon- talen Ebene hintereinander angeordnet sein.US Pat. No. 6,108,942 describes a dryer for sliced veneers, in which the guidance of two conveyor belts forms a straight and a curved drying path, each of the paths being able to be arranged in a plurality of horizontal planes to be traversed one behind the other. Drying zones can be arranged one behind the other in a horizontal plane.
Die bekannten Trockner für Messerfurniere haben den Nachteil, dass sich die einzelnen Trocknungszonen nicht klar trennen lassen. Besonders kritisch ist diese mangelnde Trennbarkeit, wenn Abluft aus z.B. einer ersten Trocknungszone in eine zweite eingeleitet wird. Hierbei ist immer eine Rückströmung von Trocknungsmedium aus der zweiten in die erste Trocknungszone zu beobachten, also eine Vermischung der Trocknungsparameter. Die Praxis hat gezeigt, dass zwischen den einzelnen Trocknungszonen Temperaturunterschiede von maximal 30° C eingehalten werden können; entsprechend ungenau lässt sich eine gewünschte Feuchte des Trocknungsmediums und der Furniere in den einzelnen Zonen des Trockners einstellen. Dies führt dazu, dass die Furniere keine optimale Qualität haben und z.B. Druckstellen durch die Bänder, Risse und/oder Welligkeit aufweisen. Umlenkung bzw. Umlenken bedeutet im folgenden, dass die Transportbänder nach der Umlenkung so geführt sind, dass sich die generelle Transportrichtung, also ohne Berücksichtigung von schleifen- und/oder wellenförmiger Führung, von einem Ende des Trockners kommend um circa 180° zum selben Ende gehend ändert. Die Transportebenen sind hierbei parallel oder annähernd parallel.The known dryers for sliced veneers have the disadvantage that the individual drying zones cannot be clearly separated. This lack of separability is particularly critical when exhaust air is introduced from, for example, a first drying zone into a second. A backflow of drying medium from the second into the first drying zone can always be observed, that is to say a mixing of the drying parameters. Practice has shown that temperature differences of up to 30 ° C can be maintained between the individual drying zones; a desired moisture content of the drying medium can be correspondingly inaccurate and adjust the veneers in the individual zones of the dryer. This leads to the fact that the veneers are not of optimal quality and, for example, show pressure marks due to the bands, cracks and / or waviness. In the following, deflection or deflection means that the conveyor belts are guided after the deflection in such a way that the general direction of transport, i.e. without taking into account loop and / or wave-shaped guidance, comes from one end of the dryer by approximately 180 ° to the same end changes. The transport levels are parallel or almost parallel.
Aufgabe der Erfindung ist es, einen Trockner für Messerfurniere zu schaffen, bei dem in den Trocknungszonen die Trocknungsparameter über weite Bereiche gezielt einstellbar sind und so Furniere mit optimaler Qualität erzeugt werden können.The object of the invention is to provide a dryer for sliced veneers, in which the drying parameters can be selectively adjusted over wide areas in the drying zones and thus veneers with optimal quality can be produced.
Die Aufgabe ist durch die kennzeichnenden Merkmale des Anspruchs 1 gelöst. Durch die Anordnung der Trocknungszonen übereinander in horizontalen Ebenen wird ohne zusätzlichen Dichtungsaufwand verhindert, dass nennenswerte Mengen an Trock- nungsmedium von einer Trocknungszone in eine angrenzende Trocknungszone übertritt. Dies bewirkt, dass in jeder einzelnen Trocknungszone gezielt in Abhängigkeit von der Holzart ein optimales Trocknungsklima eingestellt werden kann, ohne dass die angrenzenden Trocknungszonen hierdurch beeinflusst werden. Die Transportbänder sind hierbei zumindest beim Übergang von einer der Trocknungszonen in die folgende um- gelenkt, so dass sich also die generelle Transportrichtung beim Übergang von einer in die nächste Trocknungszone ändert.The object is achieved by the characterizing features of claim 1. The arrangement of the drying zones on top of one another in horizontal planes prevents significant amounts of drying medium from passing from one drying zone into an adjacent drying zone without additional sealing effort. This means that an optimal drying climate can be set in each individual drying zone depending on the type of wood, without influencing the adjacent drying zones. The conveyor belts are redirected at least during the transition from one of the drying zones to the next one, so that the general direction of transport changes during the transition from one to the next drying zone.
Die Transportbänder sind bei gleicher Länge der Trockenstrecke insgesamt kürzer als bei Anordnung der Trocknungszonen in einer Ebene, weil die Rückführung zum Trocknereingang über eine wesentlich kürzere Strecke erfolgt. Ein weiterer Vorteil ist, dass durch die übereinander angeordneten Trocknungszonen Fläche für die Aufstellung des Trockners eingespart wird.With the same length of the drying section, the conveyor belts are shorter overall than when the drying zones are arranged on one level, because the return to the dryer entrance takes place over a considerably shorter distance. Another advantage is that the drying zones arranged one above the other save space for the installation of the dryer.
Die Unteransprüche betreffen die vorteilhafte Ausgestaltung der Erfindung.The subclaims relate to the advantageous embodiment of the invention.
Die räumliche Trennung der Umlenkwalzen, die im Übergang von einer der Trocknungszonen zur nächsten angeordnet sind, von den Trocknungszonen nach Anspruch 2 ermöglicht eine noch bessere Abschottung zwischen den Trocknungszonen und eine einfachere Bauweise der Umlenkung. Die zusätzliche Umlenkung der Transportbänder in einer der Trocknungszonen nach Anspruch 3 verlängert die Strecke in dieser Trocknungszone bei vergleichsweise geringem Aufwand und erhöht somit die Leistung des Trockners. Die Erstreckung des geradlinigen Verlaufs der Transportbänder bis in zumindest einen Teil der zweiten Trocknungszone nach Anspruch 4 bewirkt, dass eine erste Umlenkung der Transportbänder und damit ein erhöhter Druck auf die Furniere erst dann erfolgt, wenn die Oberflächen der Furniere bereits weitestgehend getrocknet sind. Hierdurch wird sicher verhindert, dass das Muster der Transportbänder auf den Oberflächen eingedrückt und somit sichtbar ist. Die Unterteilung des Transportbands gemäß Anspruch 5 ermöglicht es, den auf die Furniere wirkenden Druck durch die Transportbänder in der Bügelstrecke von dem Druck im übrigen Teil des Trockners zu entkoppeln. Daher kann der Druck in der Bügelstrecke optimal eingestellt werden.The spatial separation of the deflection rollers, which are arranged in the transition from one of the drying zones to the next, from the drying zones according to claim 2 enables an even better partitioning between the drying zones and a simpler construction of the deflection. The additional deflection of the conveyor belts in one of the drying zones according to claim 3 extends the distance in this drying zone with comparatively little effort and thus increases the performance of the dryer. The extension of the straight course of the conveyor belts to at least part of the second drying zone according to claim 4 means that a first deflection of the conveyor belts and thus an increased pressure on the veneers only takes place when the surfaces of the veneers have already largely dried. This reliably prevents the pattern of the conveyor belts from being pressed into the surfaces and thus being visible. The subdivision of the conveyor belt according to claim 5 makes it possible to decouple the pressure acting on the veneers by the conveyor belts in the ironing section from the pressure in the rest of the dryer. The pressure in the ironing section can therefore be optimally adjusted.
Drei Trocknungszonen nach Anspruch 6 erlauben eine optimale Anpassung der Trock- nungsbedingungen an die Bedürfnisse.Three drying zones according to claim 6 allow an optimal adaptation of the drying conditions to the needs.
Wenn die Transportbänder wie nach Anspruch 7 im geradlinigen Verlauf unterstützt sind, kann die Vorspannung der Transportbänder gering sein, ohne dass sie unzulässig durchhängen. Hierdurch wird der Druck auf die Furniere in diesem Abschnitt weiter vermindert. Ein Sensor nach Anspruch 8 erlaubt in Verbindung mit einer Auswerte- und Regeleinrichtung die optimale Anpassung der Trocknung an unterschiedliche Qualitäten der Furniere.If the conveyor belts are supported in a straight line as claimed in claim 7, the pretensioning of the conveyor belts can be low without them sagging inadmissibly. This further reduces the pressure on the veneers in this section. A sensor according to claim 8, in conjunction with an evaluation and control device, allows the drying to be optimally adapted to different qualities of the veneers.
Radialventilatoren nach Anspruch 9 lassen eine besonders kompakte Bauweise des Trockners zu. Mittel zur Abluftführung aus einer der Trocknungszonen in eine andere nach Anspruch 11 erlauben auf einfache Weise eine Anfeuchtung des Trocknungsmediums in der Trocknungszone, in welche die Abluft eingeleitet wird. Es kann hier eine höhere Gutstemperatur gefahren werden, die eine sichere Plastifizierung von Ligninbrücken in den Furnieren gewährleistet und so zu elastischen Furnieren führt. Die Erfindung wird anhand eines in der Zeichnung schematisch dargestellten Beispiels weiter erläutert. Es zeigen Figur 1 einen Längsschnitt durch einen Trockner Figur 2 einen Querschnitt durch einen Trockner längs der Linie A-B und Figur 3 einen Querschnitt durch einen Trockner eines anderen Ausführungsbeispiels.Radial fans according to claim 9 allow a particularly compact design of the dryer. Means for routing exhaust air from one of the drying zones into another according to claim 11 allow a humidification of the drying medium in the drying zone into which the exhaust air is introduced in a simple manner. A higher material temperature can be reached here, which ensures the safe plasticization of lignin bridges in the veneers and thus leads to elastic veneers. The invention is further explained using an example shown schematically in the drawing. FIG. 1 shows a longitudinal section through a dryer Figure 2 shows a cross section through a dryer along the line AB and Figure 3 shows a cross section through a dryer of another embodiment.
Wie aus den Figuren ersichtlich umschließt ein Gehäuse 1 einen Trocknungsraum, der drei Trocknungszonen 2, 3, 4 umfasst. Die Trocknungszonen 2, 3, 4 sind in horizonta- len Ebenen übereinander angeordnet und durch Böden 11 voneinander getrennt. Von einem Trocknereingang 5, der nach Figur 1 links unten angeordnet ist, sind zwei endlose Transportbänder 6 parallel und in kurzem Abstand zueinander oder sich berührend nacheinander durch die Trocknungszonen 2, 3, 4 zu einem Trocknerausgang 7 geführt, der an einer dem Trocknereingang 5 gegenüberliegenden Seite des Trock- nungsraums angeordnet ist. Die Transportrichtung ist durch Pfeile 8 verdeutlicht. Am Trocknereingang 5 ist das hier untere Transportband 6 so geführt, dass es eine kurze Strecke aus dem Trockner herausragt. Die Transportbänder 6 sind mit einem regelbaren Antriebssystem ausgerüstet und vom Trocknerausgang 7 einzeln für sich über Rollen und eine Spannvorrichtung zum Trocknereingang 5 zurückgeführt. In der ersten Trocknungszone 2 und in der (in Transportrichtung gesehen) ersten Hälfte der zweiten Trocknungszone 3 sind die Transportbänder 6 in Form von flachen Wellen, also annähernd geradlinig in einer Ebene geführt. Hierfür sind in Transportrichtung beabstandet Stützrollen 9 angeordnet, wovon nur ein Teil dargestellt ist. Die Längsachsen der Stützrollen 9 sind horizontal sowie senkrecht zur Transportrich- tung ausgerichtet. Die Transportbänder 6 sind über die Stützrollen 9 geführt. Am Ende der ersten Trocknungszone 2 sind die Transportbänder 6 so über drei Umlenkwalzen 10 in die zweite Trocknungszone 3 umgelenkt, dass die generelle Transportrichtung um 180° geändert ist. Hierbei sind die untere Begrenzung der unteren Umlenkwalze 10 und die obere Begrenzung der oberen Umlenkwalze 10 in einer in etwa mittigen Ebene der entsprechenden Trocknungszone 2, 3.As can be seen from the figures, a housing 1 encloses a drying room which comprises three drying zones 2, 3, 4. The drying zones 2, 3, 4 are arranged one above the other in horizontal planes and separated from one another by floors 11. From a dryer inlet 5, which is arranged at the bottom left according to FIG. 1, two endless conveyor belts 6 are guided parallel and at a short distance from one another or touching one after the other through the drying zones 2, 3, 4 to a dryer outlet 7 which is located at an opposite end of the dryer inlet 5 Side of the drying room is arranged. The direction of transport is illustrated by arrows 8. At the dryer entrance 5, the lower conveyor belt 6 is guided so that it protrudes a short distance from the dryer. The conveyor belts 6 are equipped with a controllable drive system and are returned individually from the dryer outlet 7 via rollers and a tensioning device to the dryer inlet 5. In the first drying zone 2 and in the first half (seen in the direction of transport) of the second drying zone 3, the conveyor belts 6 are guided in the form of flat waves, that is to say approximately in a straight line in one plane. For this purpose, support rollers 9 are arranged spaced apart in the transport direction, only a part of which is shown. The longitudinal axes of the support rollers 9 are aligned horizontally and perpendicularly to the transport direction. The conveyor belts 6 are guided over the support rollers 9. At the end of the first drying zone 2, the conveyor belts 6 are deflected into the second drying zone 3 via three deflecting rollers 10 in such a way that the general direction of transport is changed by 180 °. Here, the lower boundary of the lower deflecting roller 10 and the upper boundary of the upper deflecting roller 10 are in an approximately central plane of the corresponding drying zone 2, 3.
In der zweiten Hälfte der zweiten Trocknungszone 3 beginnt die Bügelstrecke. Hierfür ist eine Vielzahl von in einer horizontalen Ebene beabstandeten Walzen 12 angeordnet, wobei deren Längsachsen rechtwinklig zur Transportrichtung ausgerichtet sind. Der Achsabstand zweier der Walzen 12 entspricht in etwa dem dreifachen Radius ei- ner der Walzen 12. Die Transportbänder 6 sind schleifenförmig abwechselnd über und unter die Walzen 12 geführt. Am Ende der zweiten Trocknungsstufe 3 sind die Transportbänder 6 von der letzen Walze 12 unten über eine weitere Umlenkwalze 10 auf eine erste einer Vielzahl von Walzen 13 der dritten Trocknungsstufe 4 geführt und so um 180° umgelenkt. Die Walzen 13 der dritten Trocknungsstufe 4 sind in einer horizontalen Ebene angeordnet, wobei die Längsachsen rechtwinklig zur Transportrichtung ausgerichtet sind. Die Walzen 13 weisen den gleichen Durchmesser auf wie die Walzen 12 der zweiten Trocknungsstufe 3. Der Achsabstand der Walzen 13 beträgt in etwa das dreifache ih- res Radius. Die schleifenförmige Führung der Transportbänder 6 setzt sich in der dritten Trocknungszone 4 fort.The ironing section begins in the second half of the second drying zone 3. For this purpose, a multiplicity of rollers 12 spaced apart in a horizontal plane are arranged, their longitudinal axes being aligned at right angles to the direction of transport. The center distance of two of the rollers 12 corresponds approximately to three times the radius of one of the rollers 12. The conveyor belts 6 are alternately guided in a loop above and below the rollers 12. At the end of the second drying stage 3, the conveyor belts 6 are guided from the last roller 12 below via a further deflecting roller 10 to a first of a plurality of rollers 13 of the third drying stage 4 and are thus deflected by 180 °. The rollers 13 of the third drying stage 4 are arranged in a horizontal plane, the longitudinal axes being oriented at right angles to the direction of transport. The rollers 13 have the same diameter as the rollers 12 of the second drying stage 3. The center distance of the rollers 13 is approximately three times their radius. The loop-shaped guidance of the conveyor belts 6 continues in the third drying zone 4.
Jeder Trocknungszone 2, 3, 4 sind Mittel zum Aufblasen von Trocknungsmedium auf die Furniere zugeordnet. Das Trocknungsmedium ist normalerweise Luft, die im Kreislauf geführt ist. Die Mittel zum Aufblasen umfassen für jede Trocknungszone 2, 3, 4 mindestens einen Ventilator, hier einen Radialventilator 14 mit regelbarem Antrieb, mindestens einen Wärmetauscher 15 mit regelbarer Heizmittelzuführung, eine Vielzahl von Düsenkästen 16 in bekannter Anordnung, von denen in Figur 1 nur ein Teil dargestellt ist, eine Abluftleitung 17 mit Regelklappe sowie verschiedene Kanäle zum Sammeln und Verteilen von Trocknungsmedium. Der Radialventilator 14 ist mit senkrechter Antriebsachse an einem horizontalen Teil des Gehäuses 1 befestigt.Each drying zone 2, 3, 4 is assigned means for inflating drying medium onto the veneers. The drying medium is usually air that is circulated. The means for inflating comprise for each drying zone 2, 3, 4 at least one fan, here a radial fan 14 with a controllable drive, at least one heat exchanger 15 with a controllable supply of heating medium, a large number of nozzle boxes 16 in a known arrangement, of which only a part in FIG. 1 is shown, an exhaust air line 17 with control valve and various channels for collecting and distributing drying medium. The radial fan 14 is fastened to a horizontal part of the housing 1 with a vertical drive axis.
In einem Bereich vor dem Trocknereingang 5 ist ein Sensor 18 zur Bestimmung der Feuchte der ungetrockneten Furniere angeordnet. Der Sensor 18 ist an eine entsprechende Auswerteeinheit angeschlossen.A sensor 18 for determining the moisture of the undried veneers is arranged in an area in front of the dryer inlet 5. The sensor 18 is connected to a corresponding evaluation unit.
Zu einer Trockeneinrichtung für Messerfurniere gehören außer dem Trockner nicht dargestellte Vorrichtungen wie eine Zuführvorrichtung, welche die Furniere auf das an der Übergabestelle untere Transportband 6 übergibt, ein Kühler für die Furniere und eine Austragsvorrichtung.In addition to the dryer, a drying device for sliced veneers includes devices, not shown, such as a feed device which transfers the veneers to the lower conveyor belt 6 at the transfer point, a cooler for the veneers and a discharge device.
Abweichend zum beschriebenen Beispiel ist es möglich, nur zwei Temperaturzonen 2, 3 anzuordnen. Hierbei ist die Bügelstrecke immer in der zweiten Trocknungszone 3, während der geradlinig verlaufende Teil der Transportbänder 6 in der ersten Trocknungszone 2 und gegebenenfalls in einem Teil der zweiten Trocknungszone 3 angeordnet ist.In contrast to the example described, it is possible to arrange only two temperature zones 2, 3. Here, the ironing section is always in the second drying zone 3, while the rectilinear part of the conveyor belts 6 is arranged in the first drying zone 2 and possibly in a part of the second drying zone 3.
Die Transportbänder 6 können innerhalb einer oder mehrerer der Trocknungszonen 2, 3, 4 um 180° umgelenkt sein, um die Transportstrecke und somit Aufenthaltszeit der Furniere innerhalb der entsprechenden Trocknungszone 2, 3, 4 zu verlängern. Die Umlenkung der Transportbänder 6 in die nächste Trocknungszone 3, 4 bzw. der Austrag der Furniere erfolgt dann auf der selben Seite des Trocknungsraums wie der Einlauf in die entsprechende Trocknungszone 2, 3, 4. Weiterin kann jede Umlenkung der Transportbänder 6 von einer Trocknungszone 2, 3 in die nächste außerhalb der entsprechenden Trocknungszonen 2, 3, 4 angeordnet sein. Hierfür sind die Umlenkungen durch z.B. Bleche von den Trocknungszonen 2, 3, 4 abgetrennt. In einer Ausführungsart der Erfindung ist das Transportband 6, das in der Bügelstrecke oben angeordnet ist, zweigeteilt. Das bedeutet, dass zu Beginn der nach Figur 1 dritten Trocknungszone 4 das obere Transportband 6 endet und unmittelbar anschließend ein neues oberes Transportband beginnt. Hierbei ist das in der Bügelstrecke obere Transportband 6 so ausgeführt, dass es hier einen höheren Druck auf die Furniere ausübt als im übrigen Teil des Trockners. Dies kann z.B. durch eine höhere Vorspannung und/ oder ein besonders großes Flächengewicht dieses Transportbands 6 erreicht werden.The conveyor belts 6 can be deflected by 180 ° within one or more of the drying zones 2, 3, 4 in order to extend the transport distance and thus the time of stay of the veneers within the corresponding drying zone 2, 3, 4. The deflection of the conveyor belts 6 into the next drying zone 3, 4 or the discharge of the veneers then takes place on the same side of the drying room as the entry into the corresponding drying zone 2, 3, 4. Furthermore, each deflection of the conveyor belts 6 from one drying zone 2, 3 into the next one can be arranged outside the corresponding drying zones 2, 3, 4. For this purpose, the deflections are separated from drying zones 2, 3, 4 by, for example, metal sheets. In one embodiment of the invention, the conveyor belt 6, which is arranged at the top in the ironing section, is divided into two. This means that at the beginning of the third drying zone 4 according to FIG. 1, the upper conveyor belt 6 ends and a new upper conveyor belt begins immediately afterwards. Here, the upper conveyor belt 6 in the ironing section is designed such that it exerts a higher pressure on the veneers than in the rest of the dryer. This can be achieved, for example, by a higher pretension and / or a particularly large basis weight of this conveyor belt 6.
Ein anderes Ausführungsbeispiel, das in Figur 3 dargestellt ist, unterscheidet sich in folgenden Merkmalen von dem Beispiel gemäß den Figuren 1 und 2: Die Radialventilatoren 14 sind mit horizontaler Drehachse und alle an nur einer Seite des Gehäuses 1 angeordnet. Hierdurch kann für den gesamten Trockner das Gehäuse 1 quaderför- mig ausgebildet sein, ohne Ein- und/oder Ausbuchtungen.Another exemplary embodiment, which is shown in FIG. 3, differs in the following features from the example according to FIGS. 1 and 2: The radial fans 14 are arranged with a horizontal axis of rotation and all on only one side of the housing 1. As a result, the housing 1 can be cuboid-shaped for the entire dryer, without indentations and / or bulges.
Im Betrieb werden die Furniere, die blattförmig von einem Holzblock mit einer Dicke von z.B. 0,2 bis 4,0 mm abgeschnitten sind, durch die Zuführvorrichtung kurz vor dem Trocknereingang 5 auf das an dieser Stelle untere Transportband 6 gegeben. Hierbei liegen die Furniere weitgehend flach auf dem Transportband 6. Bevor die Furniere durch das Transportband 6 in den Trockner transportiert werden, wird ihre Feuchte, also die Wassermenge pro Menge trockenem Holz gemessen. Sobald die Furniere in den Trockner eintreten, werden sie von dem oberen Transportband 6 bedeckt und infolge seines Eigengewichts flach auf das untere Transportband 6 gedrückt. In jeder der Trocknungszonen 2, 3, 4 saugen die zugeordneten Ventilatoren 14 die Trocknungsluft aus der entsprechenden Trocknungszone 2, 3, 4 ab und drücken sie durch die zugeordneten Kanäle zum Verteilen und die Wärmetauscher 15 in die Düsenkästen 16, die die Trocknungsluft durch die Transportbänder 6 auf die Furniere richten. Auf diese Weise wird die Trocknungsluft für jede Trocknungszone 2, 3, 4 im Kreislauf geführt, wie in Figur 2 durch Pfeile angedeutet ist. Ein Teil der Trocknungsluft wird vor der Aufheizung in den Wärmetauschern 15 als Abluft durch die Abluftleitungen 17 ausgeschleust. Eine Abluftführung, das heißt die Einleitung von Trocknungsluft vor der Aufheizung in den Wärmetauschern 15 aus einer der Trocknungszonen 2, 3, 4 in eine andere, erfolgt über Klappen 19 in den Böden 1 in eine der oder in die nächsten Trocknungszonen 3, 4, um hier die (absolute) Feuchte der Luft zu erhöhen und so die Einstellung von höheren Trocknungslufttemperaturen zu erlauben. In der ersten Trocknungszone 2 werden die Furniere im wesentlichen geradlinig geführt, wobei sich die leichte Wellenbewegung aus der Unterstützung durch die Stütz- rollen 9 ergibt. Diese Führung bewirkt, dass die Furniere nur einem geringen Druck ausgesetzt sind, der ihre Oberflächen nicht schädigt. Temperatur und Feuchte der Trocknungsluft werden so eingestellt, dass die Oberflächen der Furniere weitgehend getrocknet werden. Hierdurch werden Verfärbungen und die sogenannte Verschalung (Schrumpfen der Oberfläche, das durch das noch feuchte Innere behindert wird und so zu Spannungen und Rissen in der Oberfläche führt) der Furniere vermieden.In operation, the veneers, which are cut in sheet form from a block of wood with a thickness of, for example, 0.2 to 4.0 mm, are placed on the lower conveyor belt 6 at this point by the feed device shortly before the dryer inlet 5. Here the veneers lie largely flat on the conveyor belt 6. Before the veneers are transported through the conveyor belt 6 into the dryer, their moisture, ie the amount of water per amount of dry wood, is measured. As soon as the veneers enter the dryer, they are covered by the upper conveyor belt 6 and pressed flat against the lower conveyor belt 6 due to its own weight. In each of the drying zones 2, 3, 4, the associated fans 14 draw off the drying air from the corresponding drying zone 2, 3, 4 and press it through the assigned channels for distribution and the heat exchangers 15 into the nozzle boxes 16, which carry the drying air through the conveyor belts 6 aim at the veneers. In this way, the drying air is circulated for each drying zone 2, 3, 4, as indicated in FIG. 2 by arrows. Some of the drying air is discharged through the exhaust air lines 17 as exhaust air in the heat exchangers 15 before being heated. An exhaust air guide, that is, the introduction of drying air before heating in the heat exchangers 15 from one of the drying zones 2, 3, 4 into another, takes place via flaps 19 in the trays 1 into one or the next Drying zones 3, 4, in order to increase the (absolute) humidity of the air and thus to allow the setting of higher drying air temperatures. In the first drying zone 2, the veneers are guided essentially in a straight line, the slight wave movement resulting from the support by the support rollers 9. This guiding means that the veneers are only exposed to a slight pressure that does not damage their surfaces. The temperature and humidity of the drying air are set so that the surfaces of the veneers are largely dried. This prevents discolouration and the so-called cladding (shrinking of the surface, which is hampered by the still damp interior and thus leads to tension and cracks in the surface) of the veneers.
Am Ende der ersten Trocknungszone 2 werden die Furniere nach oben in die zweite Trocknungszone 3 geleitet, wobei sich die generelle Transportrichtung um 180° ändert.At the end of the first drying zone 2, the veneers are directed upwards into the second drying zone 3, the general direction of transport changing by 180 °.
In der zweiten Trocknungszone 3 werden die Furniere zunächst im wesentlichen geradlinig und anschließend schleifenförmig um die Walzen 12 geführt. Hierbei durch- laufen die Furniere zwischen den Walzen 12 eine geradlinige Strecke, deren Länge mindestens dem Durchmesser der Walzen 12 entspricht. Temperatur und Feuchte der Trocknungsluft werden so eingestellt, dass die Feuchte der Furniere zu Beginn der Bügelstrecke, also in etwa der Mitte der zweiten Trocknungszone 3, mindestens 30 % beträgt. Am Ende der zweiten Trocknungszone 3 werden die Furniere nach oben in die dritte Trocknungszone 4 geleitet, wobei sich die Transportrichtung wieder um 180° ändert.In the second drying zone 3, the veneers are first guided in a substantially straight line and then in a loop around the rollers 12. Here, the veneers run between the rollers 12 in a straight line, the length of which corresponds at least to the diameter of the rollers 12. The temperature and humidity of the drying air are set so that the moisture of the veneers at the beginning of the ironing section, that is to say approximately in the middle of the second drying zone 3, is at least 30%. At the end of the second drying zone 3, the veneers are guided upwards into the third drying zone 4, the direction of transport again changing by 180 °.
In der dritten Trocknungszone 4 setzt sich die Bügelstrecke mit der schleifenförmigen Führung fort. Temperatur und Feuchte der Trocknungsluft sind so eingestellt, dass einerseits Ligninbrücken im Holz plastifiziert und so elastische Furniere gewonnen wer- den und dass andererseits die gewünschte Endfeuchte der Furniere erzielt wird.In the third drying zone 4, the ironing section continues with the loop-shaped guide. The temperature and humidity of the drying air are set so that lignin bridges in the wood are plasticized on the one hand and elastic veneers are obtained and on the other hand the desired final moisture content of the veneers is achieved.
Temperatur und Luftfeuchte von Trocknungszone zu Trocknungszone unterschiedlich und sind abhängig von der Holzart, der Eingangsfeuchte der Furniere und der Menge der Furniere. Die Geschwindigkeit der Transportbänder, die Drehzahl der Ventilatoren, die Menge der Heizmittel sowie die Abluftmengen und die Abluftführung werden ent- sprechend geregelt. Hierfür sind Automatisierungsmittel vorgesehen.The temperature and humidity vary from drying zone to drying zone and depend on the type of wood, the initial moisture of the veneers and the amount of veneers. The speed of the conveyor belts, the speed of the fans, the amount of heating medium as well as the amount of exhaust air and the exhaust air routing are regulated accordingly. Automation means are provided for this.
Nach dem Trocknen werden die Furniere in der bekannten Weise gekühlt und gestapelt. After drying, the veneers are cooled and stacked in the known manner.

Claims

Patentansprüche claims
1. Trockner für Messerfurniere mit einer Transportvorrichtung, wobei die Furniere zwischen zwei übereinander liegenden Transportbändern von einem Trocknereingang zu einem Trocknerausgang gefördert werden, mit einer Führung der Transportbänder, die in Transportrichtung zuerst geradlinig oder annähernd geradlinig und anschließend schleifenförmig um eine Vielzahl von Walzen verläuft und mit Mitteln zum Aufblasen von Trocknungsmedium auf die Furniere, wobei der Trockner mindestens zwei Trocknungszonen umfasst, in welchen unterschiedliche Temperaturen und/oder Feuchtigkeiten des Trocknungsmediums einstellbar sind, dadurch gekennzeichnet dass die Trocknungszonen (2, 3, 4) in horizontalen Ebenen übereinander angeordnet sind.1.Dryers for sliced veneers with a transport device, the veneers being conveyed between two superposed conveyor belts from a dryer inlet to a dryer outlet, with a guide of the conveyor belts which in the direction of transport initially runs in a straight line or approximately straight line and then in a loop around a large number of rollers and with means for inflating drying medium onto the veneers, the dryer comprising at least two drying zones in which different temperatures and / or moisture levels of the drying medium can be set, characterized in that the drying zones (2, 3, 4) are arranged one above the other in horizontal planes.
2. Trockner nach Anspruch 1, dadurch gekennzeichnet, dass Umlenkwalzen (10), die im Übergang von einer der Trocknungszonen (2, 3) zur nächsten angeordnet sind, von den Trocknungszonen (2, 3, 4) räumlich getrennt sind.2. Dryer according to claim 1, characterized in that deflection rollers (10), which are arranged in the transition from one of the drying zones (2, 3) to the next, are spatially separated from the drying zones (2, 3, 4).
3. Trockner nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Transportbänder (6) zusätzlich innerhalb mindestens einer der Trocknungszonen (2, 3, 4) zur Änderung der generellen Transportrichtung umgelenkt sind. 3. Dryer according to claim 1 or 2, characterized in that the conveyor belts (6) are additionally deflected within at least one of the drying zones (2, 3, 4) to change the general direction of transport.
4. Trockner nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass der geradlinige oder annähernd geradlinige Verlauf der Transportbänder (6) sich über die erste (2) und zumindest einen Teil der zweiten Trocknungszone (3) erstreckt.4. Dryer according to one of claims 1 to 3, characterized in that the rectilinear or approximately rectilinear course of the conveyor belts (6) extends over the first (2) and at least part of the second drying zone (3).
5. Trockner nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass das Transportband (6), das in der letzten Trocknunszone (4) mit ausschließlich schlei- fenförmigem Verlauf oben angeordnet ist, in zwei in Transportrichtung hintereinander angeordnete endlose Abschnitte unterteilt ist.5. Dryer according to one of claims 1 to 4, characterized in that the conveyor belt (6), which is arranged in the last drying zone (4) with an exclusively loop-shaped course above, is divided into two endless sections arranged one behind the other in the transport direction.
6. Trockner nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass der Trockner drei Trocknungszonen (2, 3, 4) umfasst.6. Dryer according to one of claims 1 to 5, characterized in that the dryer comprises three drying zones (2, 3, 4).
7. Trockner nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass die Transportbänder (6) im geradlinigen Verlauf unterstützt sind. 7. Dryer according to one of claims 1 to 6, characterized in that the conveyor belts (6) are supported in a straight line.
8. Trockner nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass vor oder an dem Trocknereingang (5) ein Sensor (18) zur Bestimmung der Feuchte der Furniere angeordnet ist.8. Dryer according to one of claims 1 to 7, characterized in that a sensor (18) for determining the moisture of the veneers is arranged in front of or at the dryer inlet (5).
9. Trockner nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass die Mittel zum Aufblasen von Trocknungsmittel Radialventilatoren (14) mit horizontaler Drehachse umfassen.9. Dryer according to one of claims 1 to 8, characterized in that the means for inflating drying agent comprise radial fans (14) with a horizontal axis of rotation.
10. Trockner nach einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, dass Mittel zur Trocknungsluftführung (19) aus einer der Trocknungszonen (2, 3, 4) in mindestens eine andere angeordnet sind. 10. Dryer according to one of claims 1 to 9, characterized in that means for guiding the drying air (19) from one of the drying zones (2, 3, 4) are arranged in at least one other.
EP04741402A 2003-10-21 2004-08-11 Veneer dryer Withdrawn EP1678452A1 (en)

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DE10349401A DE10349401B3 (en) 2003-10-21 2003-10-21 Veneer drying plant with stacked drying zones in successive horizontal planes and separate control of temperature and/or humidity for each drying zone
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JP2007509306A (en) 2007-04-12
KR20060061861A (en) 2006-06-08
CA2542838A1 (en) 2005-05-26
BRPI0415659A (en) 2006-12-19
DE10349401B3 (en) 2004-07-29
WO2005047793A1 (en) 2005-05-26
US20070130787A1 (en) 2007-06-14
TWI265265B (en) 2006-11-01

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