WO2019030310A1

WO2019030310A1 - Preheating device for a continuously operating press and method for preheating a pressed material mat

Info

Publication number: WO2019030310A1
Application number: PCT/EP2018/071566
Authority: WO
Inventors: Ulf KÖNEKAMP; Thilo Solawa
Original assignee: Dieffenbacher GmbH Maschinen- und Anlagenbau
Priority date: 2017-08-08
Filing date: 2018-08-08
Publication date: 2019-02-14
Also published as: DE102017118016A1

Abstract

A description is given of a preheating device (18) for a continuously operating press for producing pressed boards, in particular material boards of wood and/or other renewable agricultural products, such as particle, fibre, veneer, straw and chip boards, and also plastic panels, and a method for preheating a pressed material mat (16). The preheating device (18) comprises at least one microwave input (38), which on one side of a conveying path (20) for the pressed material mat (16) is directed with its main radiating direction (40) towards the conveying path (20). The preheating device (18) also comprises at least one reflector body (44) with at least one reflector surface (46), which is arranged facing the at least one microwave input (38) on a side of the conveying path (20) opposite from the microwave input (38) when considered in the main radiating direction (40). At least one reflector surface (46) has at least one portion that is not directed axially or parallel to the main radiating direction (40) of the at least one microwave input (38).

Description

PREHEATING DEVICE FOR A CONTINUOUSLY WORKING PRESS

The invention relates to a preheating device for a continuously operating press for producing press plates, in particular material plates made of wood and / or other renewable agricultural products, such as chip, fiber, veneer, straw and chipboard plates, and also plastic plates, for preheating a

Pressgutmatte, with at least one microwave coupling, which is directed on one side of a conveying path for the Pressgutmatte with its main radiation direction to the conveying path, and with at least one reflector body with at least one

Reflector surface, which on one of the at least one microwave coupling in the main radiation direction considered opposite side of the conveying path of the arranged at least one microwave coupling.

Furthermore, the invention relates to a method for preheating a pressed product mat in the course of the production of press plates, in particular material plates made of wood and / or other renewable agricultural products such as chipboard, fiber, veneer, straw and Schnitzelplatten, and plastic plates, in which of a Side of one

Conveying path for the pressed material mat microwaves are sent in a Hauptstrahlrichtung in the pressed material mat and possibly through the Pressgutmatte

passing microwaves viewed in the main beam direction

opposite side of the conveying path are reflected back to the pressed material mat.

From EP 2 247 418 B1 a method and a device for preheating a pressed material mat in the course of the production of wood-based panels is known. In the method, microwaves are irradiated from one or both pressing surfaces sides in the pressed material mat for preheating the pressed material mat and the pressed material mat after transfer to a continuously operating press using pressure and heat pressed and cured. Reflectors conduct excess

Scatter radiation back into the pressed material mat.

The object of the invention is to design a preheating device and a method of the type mentioned, in which the microwaves can be used more efficiently to preheat the pressed material even more evenly.

The object is achieved in the preheating device in that at least one reflector surface has at least one portion which is not directed axially or parallel to the main radiation direction of the at least one microwave coupling.

According to the invention, at least a portion of the at least one reflector surface is inclined relative to the main beam direction such that the microwaves impinge obliquely on the at least one section from the at least one microwave coupling and are thus deflected with respect to the main beam direction. In this way it is achieved that the reflected microwaves in another way in the

Pressgutmatte get like the original microwaves. So can the

Pressgutmatte be penetrated evenly with microwaves. In addition, it can thus be prevented that waves forming between the at least one reflector surface and the at least one microwave coupling form. Standing waves have maxima and minima and can cause disturbances or even

Damage to at least one microwave coupling, in particular the microwave source lead. In addition, so-called hotspots, places with a locally elevated temperature, arise in pressed material mat.

By means of the deflected backscatter invention of the invention

Pressgutmatte beaten microwaves is also achieved that in the area of the conveying path of the pressed material mat by the preheating a chaotic radiation field can be achieved. In a chaotic or disordered radiation field, the microwaves are ideally not aligned uniformly. In addition, an ideal chaotic radiation field has no standing wave. The conveying path is the path on which the pressed material mat is conveyed through the preheating device. The conveying path is usually predetermined by a corresponding conveyor track. The conveyor track can be an endless continuous

circulating conveyor belt. The conveyor track can advantageously as

Conveyor belt, forming belt, roller conveyor or the like can be realized.

Advantageously, the conveying path can describe a surface, in particular a plane, in which a direction of production of the pressed material mat by the

Preheating is or to which the production direction is parallel. The Pressgutmatte may advantageously consist of fibers, chips, strands, veneers or similar goods or materials or have these. The pressed material may be strewn or laid on the conveyor track, with which it through the

Preheating device can be performed. With the conveyor track, the pressed material mat can be conveyed to an inlet of a following continuously operating press. In the press, the pressed material mat becomes a press plate, in particular one

Material plates, pressed.

Depending on the thickness of the pressed material mat to be heated and depending on the frequency of the microwaves used, the pressed product mat can be penetrated differently. Microwaves which pass through the pressed material mat are reflected back with the corresponding at least one reflector surface.

The preheating device according to the invention can be realized as a microwave oven, in particular as a microwave continuous furnace. The at least one microwave coupling can radiate into a space of the preheating device. The room may be closed to the outside with respect to microwaves to prevent microwaves from entering the environment. The space of the preheating device, in which the preheating of the pressed material mat takes place, can be used as a preheating space, in particular a furnace space or

Furnace chamber, to be called.

Advantageously, with the least one microwave coupling

Microwaves with the frequency of 915 MHz or 2.45 GHz are used. The frequency is not determined exactly to the specified frequency, it can be used in this way in particular legally permitted frequency bands become. However, the invention is not limited to these frequencies, and microwaves in other frequency ranges can also be used.

Microwaves with a frequency of 915 MHz are known to have a greater penetration depth into the material of the press mat than microwaves with a frequency of 2.45 GHz. For microwaves with the frequency of 915 MHz, the penetration depth in common press material mats can be about 0.489 m. At a microwave frequency of 2.45 GHz, the penetration depth can be about 0.183 m. If the mat thickness is smaller than the penetration depth, some of the microwaves will leave the press mat on the opposite side. The microwaves so unused out of the pressed material mat out. The reflection according to the invention enables the use of these emerging microwaves. With the invention can therefore also at high

Throughput speeds of the pressed material mat are preheated by the preheating relatively efficient press material mats efficiently.

Advantageously, all microwave couplings can be the same or

use different microwave frequencies.

Advantageously, a plurality of reflector surfaces on at least one

Be provided reflector body. The reflector surfaces may be similar or different. The reflector surfaces may differ in size and / or shape. At least one reflector surface may be in the form of a tile. The reflector surfaces may be inclined in the same way or differently.

In an advantageous embodiment, at least one microwave coupling can be implemented on at least one microwave source and / or at least one microwave coupling can be implemented on at least one microwave conductor.

At least one microwave injection can be realized on at least one corresponding microwave source. This way can be additional

Microwave conductors are dispensed with which the microwaves from the

Microwave source are passed to the preheating room. Alternatively or additionally, at least one microwave coupling can be implemented on at least one microwave conductor. The microwave conductor can lead to a corresponding microwave source, which in this case is more flexible,

in particular further away from the conveying path, may be arranged. In this way, a larger number of microwave couplings, in particular microwave sources and microwave conductors, can be installed over the width of the conveying path. Thus, the pressed material mat can be irradiated over its entire width with microwaves. This is particularly advantageous when using microwave frequencies with a frequency of 915 MHz, for which previously correspondingly large waveguides were required.

Advantageously, each individual microwave source can be connected via a corresponding microwave conductor to the preheating space of the preheating device. The output of each microwave conductor each forms a microwave coupling.

Advantageously, at least one microwave source based on a

Runtime tube, in particular a magnetron, a klystron or the like, or based on a semiconductor element, in particular a Gunn element, a tunnel diode or the like, or be implemented in another suitable manner.

Advantageously, at least one microwave conductor can be realized as a waveguide, coaxial line, microstrip line or in another suitable manner.

Advantageously, the preheater may have up to 300 microwave sources and more. Each microwave source may advantageously have a power between about 1 kW and about 100 kW, preferably between about 2 kW and about 50 kW, more preferably between 2 kW and 15 kW. In this way, a correspondingly large amount of energy can be introduced for heating in the pressed material mats.

In a further advantageous embodiment, a main radiation direction of at least one microwave coupling can be directed perpendicular to the conveying path and / or a main radiation direction of at least one microwave coupling can be directed obliquely to the conveying path. In a main beam direction perpendicular to Conveyance can reach the corresponding microwaves on the shortest route through the pressed material mats. Alternatively or additionally, at least one

Main beam direction be directed obliquely to the conveying path. In this way, a longer Durchdringungsweg be made possible, whereby correspondingly more energy can be transmitted to heat the Pressgutmatten.

Advantageously, either only microwave couplings with main beam directions perpendicular to the conveying path or exclusively microwave couplings with the main beam direction can be realized obliquely to the conveying path.

Alternatively, both main beam directions can be realized perpendicular to the conveying path and obliquely to the conveying path. In this way, a more uniform heating of the pressed material mat can be produced. Furthermore, the radiation field can thereby be more disordered with respect to the alignment, in particular of the polarization directions.

In a further advantageous embodiment, at least a portion of at least one reflector surface may be directed perpendicular to the conveying path and / or at least a portion of at least one reflector surface may be inclined to the

Be directed delivery route.

With an oblique orientation of at least a portion of at least one

Reflector surface can be achieved that in the case of a microwave coupling with a main beam direction perpendicular to the conveying path, the reflected microwaves are reflected at the at least one section obliquely to the main beam direction.

The use of a section directed perpendicular to the conveying path, in combination with a main jet direction directed obliquely to the conveying path, can likewise produce a reflection obliquely to the corresponding main jet direction.

Advantageously, either only sections may be provided, which are directed perpendicular to the conveying path, or only sections, which are directed obliquely to the conveying path. Alternatively, both portions which are directed perpendicular to the conveying path, as well as portions which are inclined are directed to the conveying path, be provided.

Advantageously, an angle between a tangential plane of at least a portion of at least one reflector surface and a plane perpendicular to

Main beam direction, ie an angle between the direction of the at least one

Section and the corresponding main beam direction, between about -60 ° and + 60 °, in particular between about -45 ° in + 45 °. In this region of inclination a penetration of the pressed material mat with the reflected microwaves can be improved and at the same time a more uniform but nevertheless disordered radiation field can be realized.

Advantageously, at least one section of at least one reflector surface in the production direction and / or at least one section at least one

Reflector surface against the production direction of the pressed material by the mat

Preheating be inclined.

In a further advantageous embodiment, a direction of at least one section of at least one reflector surface may be inclined towards a center of a preheating space of the preheating device. The center of the preheat space may be between an inlet of the housing of the preheater, through which the

Pressgutmatte reaches the area of the preheater, and an outlet of the housing. Furthermore, the center between corresponding

Side limits of the housing are located. By the corresponding inclination of the at least one section, the microwaves can be reflected towards the center. This prevents microwaves from entering the inlet or outlet from the preheat room

Get around. Advantageously, portions of at least one reflector surface located near the inlet may be inclined away from the inlet.

Accordingly, portions located near the outlet may be inclined away from the outlet. Advantageously, at least one reflector surface may be disposed at an inlet or an outlet of the preheater so that the microwaves are reflected back into the preheat space. In this way, a leakage radiation can be reduced and an efficiency of the preheater can be increased.

In a further advantageous embodiment, at least two microwave couplings can be provided, which can couple microwaves with spatially different polarization directions. By the different ones

Polarization directions can be a disordered microwave radiation field in the preheating, which passes through the pressed material mat, can be realized.

Advantageously, the polarization directions of at least two

Microwave couplings perpendicular to each other. Advantageously, a plurality of microwave couplings may be arranged in a row or a plurality of rows. The microwave couplings can

have in particular alternately different polarization directions. In this way, a more uniform irradiation of microwaves the

different polarization directions are made possible in the pressed material mat.

In order to achieve different polarization directions, the adjacent microwave couplings can with respect to their respective main beam direction

be turned differently. In a further advantageous embodiment, a plurality of microwave couplings can be arranged on the same side of the conveying path and / or a plurality of microwave couplings can be arranged on opposite sides of the conveying path. In this way, a space of the preheating by appropriate

Arrangement of microwave couplings are better used.

Advantageously, all microwave couplings can be arranged on the same side. In this way, the appropriate side of the

Preheating device, in particular of the housing, exclusively for the microwave Einkopplungen be provided. Accordingly, the opposite side can be provided exclusively for reflector surfaces.

Alternatively, advantageously, the microwave couplings on

be arranged opposite sides of the conveying path. So can one

more uniform irradiation of microwaves. Accordingly, the reflector surfaces can be arranged on the respective opposite sides. On one side both microwave couplings and reflector surfaces can be arranged. The microwave couplings and the reflector surfaces can be realized alternately.

Advantageously, the microwave radiation can be effected by the microwave couplings both from the bottom of space as well as from above.

Alternatively, the microwave irradiation can be done either from above or from below. In this way, depending on the design of the

Preheating and the conveyor track the appropriate arrangement of microwave couplings and reflector surfaces are specified.

In a further advantageous embodiment, a plurality of reflector surfaces may be arranged on the same side of the conveying path and / or a plurality of reflector surfaces may be arranged on different sides of the conveying path. Depending on the arrangement of the microwave couplings, the reflector surfaces can be provided only on one side or on both sides of the conveying path. Advantageously, reflector surfaces can be arranged on both sides of the conveying path even when the microwave couplings are located only on one side of the conveying path. In this way possible multiple reflections can be made possible. In a further advantageous embodiment, at least one

Main beam direction and / or at least one direction of at least a portion of at least one reflector surface to be adjustable and / or at least one

Main beam direction and / or at least one direction at least a portion of at least one reflector surface may be fixed. With adjustable main beam directions and / or directions of portions of reflector surfaces, the preheater can be adjusted to a

to achieve more uniform and efficient preheating of the pressed material mat. The directions can depend on the type and / or size of the

Pressgutmatte be adjusted. The preheating device can before the

Commissioning and / or set during operation, in particular adjusted.

The main beam directions and / or the directions of sections of

Reflector surfaces can be manually and / or automatically adjustable. To this

Way, in particular when changing the thickness of a pressed material mat and / or a change in material, a corresponding adjustment. The can

Sections of the reflector surfaces are adjusted so that the reflected microwaves can not radiate back into the corresponding opposite microwave coupling.

Fixed main beam directions and / or directions of portions of reflector surfaces can be adjusted and maintained once. Thus, a component, assembly and / or adjustment effort can be reduced. Furthermore, such a susceptibility can be reduced.

In a further advantageous embodiment, at least one reflector surface can be completely or at least partially planar and / or at least one reflector surface can be uneven, wholly or at least in sections. With flat reflector surfaces, the same reflection can be specified over a correspondingly larger surface area. Uneven reflector surfaces have the advantage that with them a chaotic radiation field can be realized more easily.

Advantageously, any suitable shaped reflector surfaces with any suitable topology for generating a chaotic radiation field in the

Preheating room can be used.

Advantageously, at least one reflector surface may be concave, convex, pyramidal and / or undulating, or the like, at least in sections his. The surface of the at least one reflector surface can also be arbitrary. It may have the shape of an egg carton, a milled reflection pattern, in particular angled strips, pyramids or the like. Advantageously, at least one microwave coupling takes place

Coupling of microwave radiation with a frequency of 915 MHz or 2.45 GHz.

Furthermore, the object is achieved in a method according to the invention in that at least a part of the passing and reflected by the Pressgutmatte

Microwave is deflected relative to the main beam direction. In this way it is prevented that the reflected microwaves are sent back on the same path on which the original microwaves came through the pressed material mat. Thus, a radiation field in the area of the pressed material mat can be realized more disorderly. Furthermore, standing waves can be prevented.

Otherwise, those in connection with the invention apply

Preheating device and the method according to the invention and their respective advantageous embodiments indicated features and advantages with each other and vice versa. The individual features and benefits can

Of course, be combined with each other, which can set other beneficial effects that go beyond the sum of the individual effects.

Further advantages, features and details of the invention will become apparent from the following description, are explained in more detail in the embodiments of the invention with reference to the drawing. Those skilled in the art will be aware of the features disclosed in the drawing, the specification and the claims in combination

expediently also consider individually and to meaningful further

Combine combinations. It show schematically

1 shows a plant for the production of press plates, with a continuous

working press and a preheating device for preheating Pressgutmatten;

Figure 2 is a spatially upper inside of the preheating device of Figure 1; FIG. 3 shows a longitudinal section of the preheating device from FIG. 1;

FIG. 4 shows a spatial lower inner side of the preheating device from FIG. 1;

FIG. 5 shows a reflector body of the preheating device from FIG. 1 according to a first exemplary embodiment;

6 shows a reflector body for a preheating device according to a second

Embodiment;

FIG. 7 shows a reflector body for a preheating device according to a third embodiment

Embodiment;

8 shows a reflector body for a preheating device according to a fourth

Embodiment.

In the figures, the same components are provided with the same reference numerals.

In the figure 1 a plant 10 for the production of press plates 12 is shown schematically. The system 10 comprises a conveyor track in the form of a forming belt 14, in the figure 1 left. On the forming belt 14 Pressgutmatten 16 are conveyed from scattered and / or applied press material by a preheating device 18 along a conveying path 20 in a production direction 22 to an inlet 24 of a continuously operating press 26. The pressed material includes, for example, wood and / or other renewable agricultural products such as chips, fibers, straw and chips, and / or plastic. The material to be pressed has been provided on the forming belt 14 before being sprinkled or deposited with a binder with which it cures in the press 26 to the pressing plates 12. In the press 26, the

Pressgutmatte 16 between two endlessly circulating steel strips 28 pressed in a manner not of interest to the press plate 12.

For better orientation, an orthogonal x-y-z coordinate system is shown in FIGS. In this case, the x-axis extends parallel to

Production direction 22, the x-y plane is spatially horizontal and the z-axis is spatially vertically upward. In the figure 1 shows the y-axis in the

Drawing level.

The conveying path 20 is predetermined by the forming belt 14 and extends within the preheating device 18 by way of example flat and spatially horizontal. The preheating device 18 will be explained in more detail below with reference to Figures 2 to 4. FIG. 2 shows the spatially upper inner side of a housing 30 of the preheating device 18. FIG. 4 shows the spatially lower inner side of the housing 30

The preheater 18 is as a microwave oven, preferably as

Microwave continuous furnace designed. A longitudinal section of the preheating device 18 is shown in FIG. The preheating device 18 comprises the microwave-tight housing 30, which surrounds a preheating chamber 32. The preheating chamber 32 has an inlet 34 and an outlet 36, through which the forming belt 14 leads into the preheating room 32 and leads out of this.

Spatially above in the housing 30 and spatially down in the housing 30 are each a plurality of microwave Einkopplern 38 is arranged, which are implemented at outputs of corresponding microwave conductors. The upper microwave Einkoppler 38 and the lower microwave Einkoppler 38 are located with respect to the conveying path 20 on opposite sides. The microwave conductors each come from corresponding microwave sources, not shown in the figures. The microwave sources may be, for example, magnetrons, klystrons or microwave sources based on semiconductors.

By way of example, for the upper microwave Einkoppler 38 a total of 36

Einkopplungspunkte or microwave sources used. For the lower microwave Einkoppler 38 32 Einkopplungspunkte or microwave sources are used. Each microwave Einkoppler 38 may be assigned its own microwave source. Depending on the power and design, however, a microwave source can also supply microwaves to several microwave input couplers. It can also be used more or less microwave sources. The used

Microwave sources may have a microwave power of 1 kW to 100 kW, preferably between about 2 kW and about 50 kW, more preferably between 2 kW and 15 kW. In an alternative, not shown,

Embodiment, the microwave Einkoppler 38 can also be implemented directly on the microwave sources. In this case, can be dispensed with separate microwave conductor. This may be the case if appropriately compact Microwave sources, for example in the form of semiconductor elements, are used.

The upper microwave Einkoppler 38 are arranged by way of example in nine rows, each with four microwave Einkopplern 38. The rows each extend

spaced parallel to each other, viewed in the direction of production 22 side by side. Correspondingly, eight rows, each with four microwave input couplers 38, are arranged below in the housing 30 by way of example. Viewed in the z-direction in cross-section through the preheating device 18, the rows of the upper microwave Einkoppler 38 are offset from the rows of the lower microwave Einkoppler 38, so arranged on "gap".

The microwave Einkoppler 38 are each aligned so that their respective

Main beam direction 40, as indicated in Figure 3, by way of example perpendicular to the conveying path 20 shows.

The microwaves emitted by the microwave couplers 38 are predetermined so that they can penetrate the pressed material mats 16 over their entire thickness in the direction of the z-axis. In this way, the pressed material mat 16 is preheated inside, so that a later curing in the press 26 a faster curing is possible. With the microwave sources microwaves are generated with a microwave frequency of 915 MHz example. Microwaves with this

Frequency or lying in this allowable frequency band have in the

used Pressgutmatten 16, for example, a penetration depth of about 0.489 m. If the thickness of the pressed material mat 16 is less than the penetration depth, microwaves pass through the pressed material mat 16. Instead of the above

Microwave frequency can also microwave at other frequencies or other frequency band, for example, 2.45 GHz, can be used. These have a lower penetration depth, for example, about 0.183 m.

Each adjacent microwave Einkoppler 38 are with respect to their respective

Main beam direction 40 is rotated so that their polarization direction 42 to each other stand vertically. In this way, a chaotic radiation field in the preheating room 32, which passes through the pressed material mat 16, can be realized.

Between adjacent rows of the upper microwave Einkoppler 38 an elongate upper reflector body 44 is arranged by way of example in each case. Below the housing 30 corresponding lower reflector body 44 are arranged analogously to the upper reflector bodies 44. In contrast to the upper arrangement are below in

Production direction 22 is viewed in front of the first row of the lower microwave Einkoppler 38 and after the last row of the lower microwave Einkoppler 38 each arranged an additional lower reflector body 44. The upper and lower reflector bodies 44 extend, for example, across the width of the

Form bands 14 or even something beyond.

One of the reflector bodies 44 is shown in FIG. 5 with its viewing direction on its side facing the conveying path 20. The reflector body 44 consists of two rows, each with nine segments, each of which is an exemplary level

Reflector surface 46 form for the microwaves. At the reflector surfaces 46, the microwaves used can be reflected. The direction 47 of the reflector surfaces 46 are known to be perpendicular to selbigen and show away from them.

The reflector body 44 shown in Figure 3 and thus the reflector surfaces 46 are about a respective imaginary axis which is parallel to the y-axis, with respect to a conveyor 20, so also to the xy plane, parallel plane in each case by an inclination angle 48 of about 45th ° inclined. Accordingly, the directions 47 of the reflector surfaces 46 are each at an equal angle to the

Main beam direction 40 of the corresponding opposite microwave Einkoppler 38 inclined. Since the reflector surfaces 46 are exemplary flat, this applies equally to the directions 47 in all sections of a reflector surface 46. The directions 47 of the reflector surfaces 46 are each inclined toward a center 50. The center 50 is indicated in the figure 3 with a cross. The

Directions 47 of those reflector surfaces 46 which are closer to the inlet 34 than to the outlet 36 are inclined towards the outlet 36, whereas the directions 47 of those reflector surfaces 46 which are closer to the outlet 36 are arranged, are inclined towards the inlet 34.

With the reflector surfaces 46 are microwaves, which come from the corresponding opposite microwave Einkopplern 38 and through the

Pressgutmatte 16 pass through to the press material mat 16 so back, particularly preferably in the direction of the center 50, reflects that they are opposite to the

Main beam direction 40 of the original microwaves are deflected. In this way, a more uniform, overall chaotic radiation field in the

Pressgutmatte 16 are generated. In the chaotic radiation field are the

Polarization directions of the microwaves as disorderly.

The inclination angles 48 of the reflector bodies 44 can be adjusted. The

Setting the inclination angle 48 may be changed, for example, depending on the thickness and / or the material of the used Pressgutmatte 16.

In a method for producing the press plates 12, the pressed material with glue in the production direction 22 in front of the preheating device 18 for realizing a

Pressgutmatte 16 scattered on the forming belt 14. The pressed material mat 16 is conveyed with the forming belt 14 continuously along the conveying path 20 in the production direction 22 through the preheating device 18 and preheated there.

In the method for preheating the pressed material mat 16, microwaves in the direction of the respective microwave main beam direction 40 are sent into the pressed material mat 16 from above with the upper microwave Einkoppler 38 from above and with the lower microwave Einkopplern 38 from below. In the Pressgutmatte 16, the microwaves provide for heating. A portion of microwaves penetrates the pressed material mat 16 and emerges on the respective opposite side from the pressed material mat 16. The emerging microwaves reach the respective reflector bodies 44 and are reflected there at the corresponding reflector surfaces 46. Due to the inclination of the reflector surfaces 46, the microwaves are compared to the corresponding

Microwave main beam direction 40 deflected. The reflected microwaves 52 are sent obliquely into the pressed material mat 16 and there ensure further heating of the pressed material. The preheated Pressgutmatte 16 is further transported with the forming belt 14 to the inlet 24 of the press 26. In the press 26, the Pressgutmatte 16 is pressed in a manner of no further interest to the pressing plate 12, which leaves the press 26 at its outlet.

FIG. 6 shows an arrangement of reflector bodies 144 according to a second exemplary embodiment. In contrast to the first exemplary embodiment, a plurality of reflector bodies 144 are arranged in a row here. The

Reflector bodies 144 each have planar reflector surfaces 146. The

Reflector bodies 144 are inclined differently relative to one another.

FIG. 7 shows a reflector body 244 according to a third exemplary embodiment. The reflector body 244 has the shape of a section of a round

Cylinder jacket. The corresponding reflector surface 246 is located at

Outside of the reflector body 244 and is convex. In this way, at least a portion of the reflector surface 246 is always not directed axially to the corresponding main beam direction 40 of the opposite microwave Einkoppler 38.

FIG. 8 shows a reflector body 344 according to a fourth exemplary embodiment. The reflector body 344 has a plurality of reflector surfaces 346, which are realized on pyramidal elevations of the reflector body 344 on the side facing the corresponding microwave Einkoppler 38 side.

Bezuaszeichenliste P1575WQ:

10 plant

12 press plate

14 form band

16 pressed material mat

18 preheating device

20 conveying path

22 Production direction

24 enema

26 press

28 steel bands

30 housing

32 preheat room

34 inlet

36 outlet

38 microwave input coupler

40 main beam direction

42 polarization direction

44; 144; 244; 344 reflector body

46; 146; 246; 346 reflector surfaces

47 direction

48 tilt angle

50 center preheat room

52 Reflected Microwaves

Claims

claims

1 . Preheating device (18) for a continuously operating press (26) for

Production of pressing plates (12), in particular material plates of wood and / or other renewable agricultural products, such as chipboard, fiber, veneer, straw and chipboard, and plastic plates, for preheating a pressed material mat (16),

with at least one microwave coupling (38) which is directed on one side of a conveying path (20) for the pressed material mat (16) with its main jet direction (40) to the conveying path (20),

and at least one reflector body (44; 144; 244; 344) having at least one reflector surface (46; 146; 246; 346) disposed on one of said at least one reflector surface (46;

Microwave coupling (38) in the main radiation direction (40) considered opposite side of the conveying path (20) of the at least one microwave coupling (38) facing arranged, characterized in that at least one reflector surface (46; 146; 246; 346) at least a portion that is not axially or parallel to the main radiation direction (40) of the at least one microwave coupling (38) is directed.

2. preheating device according to claim 1, characterized in that

at least one microwave coupling (38) on at least one

Microwave source is realized and / or at least one microwave coupling (38) is realized on at least one microwave conductor.

3. preheating device according to claim 1 or 2, characterized in that a main radiation direction (40) of the microwaves at least one microwave coupling (38) is directed perpendicular to the conveying path (20) and / or the main radiation direction (40) at least one microwave coupling (38) obliquely to directed to the conveying path (20).

4. preheating device according to one of the preceding claims, characterized

characterized in that at least a portion of at least one reflector surface (46; 146; 246; 346) is directed perpendicular to the conveying path (20) and / or at least a portion of at least one reflector surface (46; 146; 246; 346) oblique to the conveying path (20). is directed.

5. preheating device according to one of the preceding claims, characterized

characterized in that a direction (47) of at least a portion of at least one reflector surface (46; 146; 246; 346) is inclined towards a center (50) of a preheat space (32) of the preheater (18).

6. preheating device according to one of the preceding claims, characterized

characterized in that at least two microwave couplings (38) are provided, which microwave with spatially different

Polarization directions (42) can couple.

7. preheating device according to one of the preceding claims, characterized

characterized in that a plurality of microwave couplings (38) on the same

Side of the conveying path (20) and / or a plurality of microwave couplings (38) on opposite sides of the conveying path (20) are arranged.

8. preheating device according to one of the preceding claims, characterized

in that a plurality of reflector surfaces (46; 146; 246; 346) are arranged on the same side of the conveying path (20) and / or a plurality of

Reflector surfaces (46; 146; 246; 346) may be arranged on different sides of the conveying path (20).

9. preheating device according to one of the preceding claims, characterized

in that at least one main radiation direction (40) and / or at least one direction (47) of at least one section of at least one reflector surface (46; 146; 246; 346) are adjustable and / or at least one main radiation direction (40) and / or at least one direction (47) at least one Section of at least one reflector surface (46; 146; 246; 346) are fixed.

10. preheating device according to one of the preceding claims, characterized

in that at least one reflector surface (46; 146; 346) is completely or at least partially planar and / or at least one

Reflector surface (246) is wholly or at least partially uneven.

1 1. Preheating device according to one of the preceding claims, characterized

characterized in that at least one microwave coupling (38), a coupling of microwave radiation with a frequency of 915 MHz or 2.45 GHz takes place.

12. A method for preheating a pressed product mat (16) in the course of the production of press plates (12), in particular material plates made of wood and / or other renewable agricultural products such as chipboard, fiber, veneer, straw and Schnitzelplatten, and plastic plates,

in which microwaves in a main jet direction (40) are sent into the pressed material mat (16) from one side of a conveying path (20) for the pressed material mat (16)

and any microwaves (52) passing through the pressed material mat (16) are reflected back to the pressed material mat (16) on the opposite side of the conveying path (20) viewed in the main jet direction (40), characterized in that at least part of the material passing through the pressed material mat ( 16) passing and reflected microwaves (52) with respect to the main radiation direction (40) is deflected.