DE1808954A1 - Method and apparatus for drying sheet material - Google Patents

Description

Method and Apparatus for Drying Sheet Material Summary The description of wood veneer sheets or other sheet material is followed by successive Conductor sections of an excited Vellenleiter and heated air flows from air brushes guided, which are arranged between the ladder sections of the Leeherlei.tung, in order to achieve a very fast drying, with which surfaces with a relatively high Moisture content are dried more than areas with lower moisture content, so that an end product of uniform moisture content is obtained. The waveguide device and the air brush device is in a thermally insulated chamber with electrical conductive walls arranged, which continuous conveyor and a Luftwnwälzsystem in one Arrangement contains which the efficiency and the appropriateness of the process operation optimized.

The invention relates to drying sheet material, and more particularly a method and apparatus for quickly and efficiently drying such Material using microwave energy in the course of a continuous process.

Many industrial products that are dried in the course of their manufacture have to be, have a thin, leaf-shaped shape and have to use special Techniques are treated that differ from those that also involve thick objects, Granules or other shaped products are used. Wood veneer sheets, glued together to form plywood form an example of a sheet material, which is usually subjected to a drying process.

The present invention was initially developed for the purpose @ to facilitate the drying of veneer sheets, and is accordingly based on the example be described by wood veneers; it goes without saying, however, that the Invention also applies to the drying of many other similarly shaped products is applicable.

The typical dimensions for veneer sheets are approximately 2.54 mm to 0.55 mm Thickness, approximately 127 mm wide and 2440 mm long. To make plywood you have to several dried veneer sheets are joined together, which is preferably happens with the help of a hot resin, during which the resin cures Pressure is applied to the veneer sheets. The quality of the product depends This largely depends on the moisture content of the veneer sheets at the time of their Connection off. The moisture content should usually be in the range of about 3 6.4 to about 8%, and what is very important, in all areas of the veneer sheet be as uniform as possible.

In the presence of local zones of relatively high moisture content in any of the veneer sheets during joining can at Release of the pressing pressure causes a phenomenon known as "explosion" to occur. It is a question of adjacent surfaces of the veneer sheets bursting apart in the damp places and is probably due to the steam pressure, which arises in the places of higher humidity. On the other hand, are there local zones with a moisture content that is below the optimal range, so can conversely, lead to jumping, brittleness and loss of strength. The problem, adjust the moisture content, d. H. one in all areas of the veneer sheets Achieving uniform moisture levels is particularly important in the plywood industry Made trouble.

Whereas in the past the veneer panels were squeezed together heated plates and dried by various other means have been used the most widespread technique currently used is an air drying chamber. Usually Such a device contains a chamber in which roller conveyor, which as "Slides" are known, on which the veneer sheets are conveyed through the drying zone will. Hot air is continuously blown through the chamber and on some devices Air brushes are used to create high velocity air currents against surfaces to straighten the veneer sheets.

This means pipes into which hot air is pumped and which arranged transversely to the conveying direction of the veneer panels and in their immediate vicinity are. The tubes are usually arranged in pairs so that the laminated panels pass between the two pipes of such a pair. Each tube points Open a long slot opposite the veneer panels to allow the hot air to flow onto it to judge.

When using air dryers of this type for drying sheets of veneer a number of problems arise. For example, the length of the procedure is undesirable long. The drying process depends on these devices Heat transfer on the surface of the veneer panels inside them, and various factors limit the generated heat flow. In particular, the surface temperature must the veneer sheets are kept below a firm limit to avoid scorching or to avoid any other depreciation of the wood. Wood is also a bad one Heat conductor, especially after partial drying. With conventional methods these factors resulted in a minimum procedural time on the order of 5 minutes. The air temperature is kept low enough to prevent any reduction To avoid product quality, a much longer process time is required.

Another consequence of the long duration of the proceedings is the fact that several parallel webs of veneer sheets at any given time the dryer must be sent if a procedure is reasonable Efficiency should be achieved without requiring extremely long rockers. This in turn requires multiple conveying devices and multiple loading and unloading devices for the product.

Another serious problem area when using conventional Air dryer is created by the difficulty of having dried veneer sheets with the to obtain advantageous even moisture content. The fresh corn leaves can differ in their total moisture content and local zones of each one Veneer sheets can in turn have different moisture contents. Have so Branches z. B. usually a higher moisture content than the surrounding area of the veneer sheet. If conventional methods are used, they remain relative moist veneer sheets and the relatively moist local zones of the individual sheets even after drying in their under different moisture content obtain. Veneer sheets with an unevenly distributed moisture content or with a total moisture content that is outside the desired range must be determined after leaving the dryer and either again fed in or withdrawn. On the other hand is a successful secondary treatment very difficult. In reducing the damp areas to the desired moisture content the other areas of the veneer sheet may become too dry.

This difficulty in adjusting the moisture content is one Major source of poor process efficiency and complication of the process, and not just when drying wood veneer sheets, but also when drying many other sheet-like materials.

To avoid some of the difficulties mentioned, treatment can be used different materials use microwave drying instead of air drying be applied.

This type of heating is unique in that it is not of depends on the heat transport inside the material, but very quickly in the inside of which generates heat. Furthermore, the generated microwave energy is in primarily in relation to the internal water content of the material. This will a moisture balance defect achieved in that in the areas of the material, which has a higher moisture content, proportionally more Heat is generated. Meanwhile, the treatment of manufactured goods is by means of Microwaves a relatively young technology, and the apparatus and devices that do have been used so far are the conditions for drying sheets of veneer or many other sheet-like materials not optimally adapted.

Sheet material can be heated up very quickly by adding is transported by an excited vilellleiter.

If the waveguide is excited in a certain way, it can go along longitudinal slots are provided on the sides of the ladder through which the Sheet material can bind through. Furthermore, the material can be made up of consecutive Conductor sections of a single waveguide pass through while it is lengthways a straight path is advanced when the waveguide is in the shape of a tangle or meander line is arranged which repeat the path of the sheet material Painting crosses. Many serious difficulties arise in practice? if you have such to make effective use of a method of drying sheets of veneer and the like want.

The microwave radiation heats up the veneer sheets as well as it also drives the moisture out of the material against its surface. This creates a layer of moisture on the surface, which in turn causes the drying process can make a difference in various ways. First of all, there must be moisture build-up be scattered on the surface when the drying process is finished and when this is to be done by evaporation as a result of microwave heating, so is either a very high wave energy is necessary9 or an undesirably long process duration necessary. The process is further complicated by the fact that such Evaporation of the surface areas of the veneer sheets at a relatively low level Temperature hold.

A very significant difficulty arises when drying after the Method with a meandering waveguide, characterized in that the energy density the microwaves at the input side of the waveguide has a maximum and in not linearly along the conductor a-b. As in the meandering arrangement the successive line sections of the waveguide across the veneer sheets extend, the conductor section is characterized by an in one Direction transversely to the veneer sheets from decreasing energy consumption, whereby the The heating effect is greatest at the ends of each Leit.rabschnittes with respect to of the electrical circuit are closest to the point of energy supply. This The energy density gradient is reversed with each subsequent transverse section of the meandering waveguide, and therefore each creates such a section some compensation for the uneven heating of the previous section. However, this is not enough to completely compensate for this effect, since the total energy density is substantially less within each waveguide section than within the previous. The end result is an unequal heat exposure across the veneer sheets after going through the entire device, with the maximum Heat applied along the edge of the veneer sheets, which apply the energy The end of the Bllaaulder waveguide was closest.

Further difficulties arise with effective use of the meandering waveguide in connection with the transport and the support of thin semi-flexible sheets of veneer in the necessarily intricate device and in terms of balancing the local energy density along the waveguide with the progressively decreasing moisture content of the wood as it passes through the device passes through. 9 '{Further difficulties arise with regard to the avoidance of the decrease in the microwave energy of the device caused by electrical Arcing can occur, and by providing adequate access to different parts of the device.

The invention provides an apparatus and a method which solve the problems mentioned by providing a method to dry of veneer sheets and other sheet material create which quickly, appropriately is highly effective and creates conditions that are consistent with product Evoke moisture content.

The invention uses a combination of microwave heating and Air drying in which the veneer sheets or similar material are continuous by a succession of spaced-apart microwave ranges Intensity sent by successive sections of an or several meandering waveguides can be formed. The surface moisture is effectively eliminated by a series of gas currents that strike the veneer sheets directed along zones @ arranged at a distance along the conveying path of the veneer sheets are.

Get the advantage of a very fast and even drying also savings that result from the process according to the invention not all of the moisture necessary to evaporate the moisture contained in the product Amount of heat must be generated by microwave energy. The microwave heating is used partly to this9 the internal moisture in the direction of the surface of the product to drift where it can be removed more economically by air currents The invention creates several design improvements that work together to improve drying In a preferred embodiment, the invention employs two independently meander-shaped waveguides fed from each other with energy, which are in simpler constructive arrangement prevail, whereby the decreasing energy density longitudinally each waveguide due to the progressive decrease in moisture content is balanced in the product during the drying processO Continue to create9 which is very important is, the prevailing multiple meander-shaped Waveguide arrangements allow the two waveguides the energy feed opposite sides of the conveying path of the veneer sheets, with the Success that the above-mentioned energy density gradients in the transverse direction are effective and a roughly uniform energy density across the veneer sheets can be set throughout the system.

The gas flows between the successive waveguide sections are preferably created by pairs of air brushes placed between them and are structurally attached to an adjacent WeXsnleiter section can to realize several constructive and functional advantages. So For example, part of the gas flow is used to flow into the adjacent waveguide section forced to blow out moisture and debris.

The invention is further trained that the waveguide and Air brush arrangement roughly along the line defined by the conveying path of the veneer sheets plane is divisible, so that part of the arrangement of the other in the Neise is preferred can be separated by lifting jacks, giving free access to the interior the arrangement for cleaning and maintenance purposes. To such a separation without making the loosening of contact connections possible by manual operation -Reactor coils of novel design used to control the moving parts of the waveguide assembly to connect with the microwave generator and the wave conductor end pieces.

The invention also provides the arrangement of the waveguide and air brush device together with a roller conveyor within a chamber before that has an air circulation system to reduce the cost of heating the air.

The chamber is preferably thermally insulated to reduce heat loss, and has electrically conductive walls to absorb microwave energy emerging from the waveguides escaped to catch. The infeed and outfeed devices for the veneer sheets at the ends of the chamber contain electrically conductive material to transport energy to avoid through them through.

The invention also provides lip-like projections along the longitudinal slots in the waveguide walls through which the veneer sheets are transported, to create wide slots that still prevent the loss of microwave energy through avoid them through. The formation of arcing at these slots is caused by specially trained lip constructions avoided.

The invention includes both the special ones, described above Refinements as well as other improvements that are described below.

Accordingly, it is an object of the invention to provide a method and a device for drying wood veneer sheets faster and more efficiently and other sheet material.

Understand the invention, as well as other advantages and embodiments best understood from the following description in conjunction with the drawingsX These show the drying in: FIG. 1 schematically and in a perspective representation of a sheet material according to the invention with some on this Purpose required parts of the device; Fig. 2 a. perspective view of a Waveguide structures that can be used according to the invention, and the through an opening in the form of a wide slot for the passage of the sheet material characterized by the waveguide, at the same time the escape of microwave energy is avoided from it; 3 is a side view of a veneer dryer according to FIG Invention; 4 shows a section through the veneer dryer parallel to the planar plane along axis 4-4 in Fig. 3; Fig. 5 is a section parallel to the elevation plane the discharge device of the veneer sheet dryer along the axis 5-5 of FIG. 4; 6 shows a cross section through the veneer sheet dryer in the longitudinal elevation the axis 6-6 in Fig. 4; 7 shows a section along the axis 7-7 in FIG An illustration of a combustible air duct coupling used in the veneer sheet dryer; Fig. 8 shows a section parallel to the plan view along the axis 8-8 in Fig. 6 to Clarification of a chain drive that is used to move certain parts apart The veneer sheet dryer is used by others to make the interior of the device accessible close; 9 shows a section in the front elevation along the axis 9-9 in Fig. 6, the central part of the device being omitted for clarity veneer dryer rmi inner items. to e Pn a sponsor to the raneport the veneer sheets; 10 is a perspective view of a choke coil which for the electrical connection of mutually movable parts of the waveguide device is used without requiring a mechanical connection; Fig. 11 a Side view of the choke coil of FIG. 10 and FIG. 12 shows a section parallel to Plan view of the choke coil along the axis 12-12 of FIG. 11.

In Figure 1, veneer sheets 21 according to the invention while they are longitudinal a predetermined conveying path, which is indicated by the arrow 22, moved along are dried by applying microwave energy to them along a multitude of zones 23, which are arranged at a distance from one another along the conveying path, comes into effect. With this process, gas flows are high velocity Air or some other gas running lengthways against the surfaces of the plywood sheets Zones 24 are directed, which are also at a distance from one another along the conveying path of the veneer sheets are arranged connected. This has a very quick drying effect with the result that the microwave energy penetrates into the veneer sheets and acts primarily on the internal moisture in such a way that along the whole Inside the wood heat is generated. In addition to this heating effect this serves to reduce the internal moisture against the surfaces of the veneer sheet to drive.

One effect of microwave heating along zones 23 is that a layer of moisture tries to form on the surface of the veneer sheets. Without the air currents along zones 24, this effect would enhance the drying process demand seeds, as the surface areas of the veneer sheets have the aspiration would stay relatively cool, which is likely due to the cooling during evaporation of the moisture film is to be returned. This slows down the drying process is avoided in the present invention by the high-speed gas flows, which are directed to the veneer sheets along the zones 24, and serve to the Dissolve and remove surface moisture films.

This way the moisture that is on the veneer sheet surface formed after each pass through a microwave zone 23 of the veneer sheet removed before entering the next microwave zone.

It is possible to put cold dry gas, generally air, into the Use zones 24 and this is preferred in some grooves because of damage of the veneer sheet surfaces due to the heat can be avoided and a product of very good quality is thereby obtainable. However, it is usually preferable Apply hot air to speed up the drying process and reduce process costs to diminish. A significant proportion of the required for drying is used here poor applied by the air flow.

This causes a saving because it is generally more economical is to apply heat by a gas stream to the extent possible than alone due to the much more expensive microwave heating. The temperature of the airflow being used with the present invention, however, can be kept much lower, than is the case with conventional hot air dryers. While the air temperatures in conventional dryers generally in the range from about 1500 C to about 2300 C, the air temperature according to the invention is generally about 1070 C. Using this relatively low air temperature according to the invention the damaging effects on the Burnierblitter are minimal. However, it is to point out that according to the invention different air temperatures are used can be, depending on the desired product quality on the one hand, and the duration of the procedure and cost aspects on the other hand. However in almost all cases the air temperatures used are lower than those commonly used in conventional air dryers, and therefore the quality of the product is improved.

An important advantage of this drying technique is that it is noticeably reduced Duration of proceedings. While sheets of veneer generally take about 5 minutes in a conventional Require air dryers are process times when using the technique according to the invention of only 20 seconds possible. This in addition to the desired shortening the duration of the procedure achieved indirect advantages. Is a high output volume in are prescribed for a reasonably sized conventional dryer multiple introduction, discharge and conveying devices for the veneer sheets necessary, to allow the simultaneous treatment of many sheets of veneer in the dryer do. These devices can to a large extent by applying the inventive Technology can be simplified because in a space-saving system in which the veneer sheets pass through the treatment zone along a single conveying path, if necessary, a large discharge volume can be achieved.

Another important advantage of the invention is the moisture balance Effect of the combination described above of the procedural stages is achieved. Because the heating effect of microwave energy is primarily due to their Effect is due to the internal moisture of the veneer sheets, takes place the heating and drying in the relatively humid areas is more intensive. As a result the finished veneer sheets have a much more uniform moisture content than was previously the case.

In one suitable for performing the operations described above Construction, the zones 23 of the microwave radiation from a series of im Spaced parallel to each other arranged waveguide sections 26 formed, the enforce the conveying path 22 of the veneer sheets and in the present embodiment have a rectangular cross-section.

For the passage of the veneer sheets through the waveguide section 26, longitudinal slots are provided in their walls, both entrance slots 27 and exit slots 28. Are the waveguide sections 26 in one of executed certain specific embodiments, such as the "TE 010 mode ", slots 27 and 28 aligned in this way do not conflict on how the waveguide works.

The air currents along the zones 24 are most advantageously through Pairs of air brushes 29 are formed, one pair between each two consecutive Waveguide sections 26 is arranged parallel to these. The two parts of one Air brush pairs 29 are on opposite sides of the conveying path 22 of the veneer sheets arranged, and are tubular conductors 31, each of which has a longitudinal slot 32 having facing the veneer sheets to a level air jet higher Speed aimed at this.

To support the veneer sheets and keep them along the conveyor path To move 22, roller conveyors 33 are used, with a pair of rollers between each a pair of air brushes 29 and the subsequent waveguide section 26 is arranged in parallel thereto, each part of a pair of rollers is arranged on both sides of the veneer sheets.

In this way, the veneer sheets are treated according to the invention, by being sent through a repeating sequence of parts, their each forms a unit and consists of a pair of conveyor rollers 33, a waveguide section 26 and a pair of air brushes 29.

The advantages of the invention are achieved in the best way by that these parts are arranged in a special way to each other and certain constructive Have peculiarities that together bring about the desired success. First A very desirable property is that the waveguides 26 should consist of two separable individual elements 34 and 36, their parting plane preferably lies in the plane which is defined by the conveying path of the veneer panels is. The division of the individual elements 34 and 36 of each Welenleiter Absohnittes is similar the division of the input and output slots 27 and 28 performed so that the Energy transport through the waveguide is not disturbed, provided that the Waveguides are designed according to a matching key. This shared Waveguide construction provides easy access to the interior of the waveguide sections 26 for the purpose of removing branches, sawdust, and other scraps Aspiring to accumulate there, and for other purposes as well.

Further advantages are realized through the application special Embodiments for the input and output slots 27 and 28, respectively, through which the veneer sheets enter and exit waveguide section 26. Is the Width of these slots in a direction perpendicular to the veneer panels is a considerable Part of a wavelength of the transmitted microwave, then can through the slot a substantial part of the energy is lost, if not a corrective construction, as described below, is provided. To this undesirable result to avoid, the entrance slots 27 may be formed so that they have a width which is very small in relation to the length of the microwave. With many Veneer sheets, as with other materials that require drying in are to be subjected to the device, however, there may be an endeavor to buckle and if then corrective action is not taken, can the veneer panels are pressed against the edges of the entrance slot 27 with as a result, if the slot is very narrow, they will be scratched or broken. To avoid this difficulty, the pair of conveyor rollers 33, which is in front of each VeLenleiterabschnitt 26 is arranged, moved very close to the entrance slot.

Electric arcs often cause major difficulties where there are partitions or openings in the walls of a waveguide; to overcome this problem, at the ends of the entrance slots 27 is one Bevel arranged, the edges of which, determining the width of the slot, gradually converge, as indicated at 37.

The exit slots 28 of the waveguide sections 26 preferably have a different construction for various reasons. First of all, the exit slots 28 cannot be made as narrow as the entrance slots 27, w without difficulty as a result To have to fear jamming of the veneer panels, since it is generally impractical is to arrange a pair of conveyor rollers 33 close to the exit slots. Second, it is desirable, as will be explained in more detail below, that subsequent pair of air brushes 29 immediately adjacent to the outlet slots 28 to be arranged and the air brush construction electrically and mechanically with the To connect waveguide structure at the exit slot. Furthermore it is Desirably, part of the gas flow from the air brushes 29 through the outlet slots 28 to align into the waveguide section 26.

Accordingly, the exit slots 28 are in to the veneer panels perpendicular direction relatively wide and have a view from each SchlitzkanFe outwardly extending lip 38. The lips 38 oonverge in the in Fig. 1 shown embodiment easily and facilitate together with the relative large width of the slot 28 the passage of the coming from the waveguide Veneer panels without jamming or damage. The lips 38 are made of conductive Material and are preferably in one piece as part of the individual waveguide elements 34 and 36 formed. The lips 38 also form a ledge on which the neighboring Airbrush lines 31 may be attached to each waveguide element 34 and 36 and one of the associated pairs of air brushes to form a unit.

This arrangement provides such a position for the slots 32 of the air brushes 29 near the outer edges of the: lips 38 in front, which is an essential part of the air flow into the adjacent waveguide section 26 through the space between the lips 38 and through the exit slot 28 is directed.

This becomes the area in which the air flow acts on the veneer sheets extends into the waveguide sections 26 and the moisture flushed out of the interior of the waveguide sections, thereby facilitating drying and the possibility of spark formation is perceived therein. This air is out the waveguide sections 26 through a plurality of openings 39 in their walls removed, the diameter of which is small enough not to prevent loss of microwaves to effect.

A very important function of the lips 38 is to prevent energy losses to prevent by the relatively wide exit slots 28. The field distribution in a waveguide of this type is such that the currents are in an axial direction along the midpoint of the sidewalls of the waveguide and the transverse ones Currents at this point are zero. In this way, a longitudinal slot 28 interrupts along the midpoint of the sidewalls the currents do not, and hence there will be none Energy radiated provided that the slit is very narrow. So caused for example, a slot less than about 2.5 cm wide in a waveguide, which is operated at 915 megahertz, very low Beck losses. However, if the Slot continued as in the present example from those mentioned above May be desirable for reasons, the field allocation will be significantly modified and Beck losses can occur. Next is the presence of dielectric Material such as the veneer sheets 21 in the slot to a drain of energy through the slot to the outside. According to the invention, this effect is achieved met through the lips 38. Energy that escapes through the slot 28 is coupled in the space between lips 38 in a higher order than in one Direction of propagation in a parallel plane. Extend the lips 38 from the Waveguide wall in a length of about a quarter of a wavelength or one odd multiples of it does this a maximum suppression of energy losses. In this condition, the lips 38 act with respect to the energy propagation perpendicular to the waveguide as a one-quarter wavelength choke. In addition, any dielectric material acts between the lips 38, e.g. B.

the veneer panels 21, by the absorption of energy in the space between the lips to create a dampening effect.

In a 915 megahertz arrangement for drying veneer sheets the typical width of the exit slits 28 may be 7.6 cm, and the lips 38 may extend outward the same distance that quartered the wavelength in free space is 33 cm.

Special constructions can be used to achieve maximum effect at each end of each pair of lips 38 are provided to avoid losses and electrical Avoid flashovers in these areas. The ends of the exit slots 28 in the waveguide walls are bevelled so that they gradually become like in the lall of the input slits 27 described earlier gradually converge, and the lips 38 are similarly arranged to converge, but without converging or to come so close that it causes sparks. this can be done in several different ways, those shown in FIG Lips 38 converge towards each other and at the same time on the middle plane of the waveguide section 26 connected to them, as shown at 41, converging run towards.

Figure 2 shows a modified embodiment for the lips. at In this modified embodiment there is again the waveguide section 26a from two separable Individual elements 34 'and 36', which along a central longitudinal plane are divisible by the waveguide. The lips 38 'in this Example are instead of converging parallel and first? corner from the waveguide section 26a by an equal amount along all points along each lip inclusive the end portions 41 'of the same to the outside. The lips 38 converge at the end portions 41 'in correspondence with the converging beveled end of the exit slot 28 ', but stop shortly before the vertex of the same, so that the ends of the ivites are at a distance from each other and form a gap wide enough to allow Avoid rollovers. In the case of a waveguide construction with the above dimensions, in which the middle parts of the lips 38 'are separated by a 7.6 cm wide gap are, the distance between the ends of the lips 38 'can generally be about 2.5 cm.

Further suppression of flashovers is achieved in the embodiment in Figure 1 caused by the fact that the air brush lines 31 made of electrically conductive Material are made, and the air brushes on the adjacent wave conductor sections 26 by means of electrically conductive connecting means, such as welding, are attached so that the air brushes in the end a training of the lips 38 that reinforce their various functions. In this context the air brushes should be arranged so that the slots 32 are about a quarter wavelength from the land of the connected Jellenleiters as the length of the lips 3d should be a quarter of a wavelength in order to reduce the emission of lxl microwave, As mentioned above, avoid. This i is desirable because the slot 32 of the air brushes the end of the connected lip 38 for electrical effects certainly.

A detailed construction of a veneer sheet dryer in accordance with the invention, Figures 3 and 4 show where a generally rectangular chamber 43 is shown with an input 44 and an output 46. How best to look Figure 4 can be seen, the chamber 43 consists in particular of electrically conductive Walls 47 to collect scattered Tçılı microwave energy. About the air heating costs To reduce, the chamber walls 47 consist of a double layer of electrical conductive material with a suitable thermal insulation 48 interposed therebetween is, except at the entrance 44 and at the exit 46. The walls 47 'of the entrance and Exit sections can have a single layer of electrically conductive material because the inner transverse walls 49, which also consist of thermal insulation, which is arranged between electrically conductive layers, between the input and exit sections and central sections 52 of the chamber.

The walls of the chamber 43 can be attached to suitable structural elements 51 attached and supported by these, and the side walls of the middle section 52 of the chamber are preferably designed as a continuous row of san doors 53, which are attached to hinges 54 which have latches 56 to a suitable Access to the interior of the chamber 43 along any desired point on either side to create the Chamber. To have good electrical contact between the edges - to create each door 53 and the adjacent fixed part of the wall 47 and to avoid air leaks to avoid this, high-frequency seals, such as. B. Copper seals 57, be arranged in between.

The inlet and outlet end portions 44 and 46 of the chamber 43 permit free access for introducing the veneer sheets into the chamber and for exiting the same out of the chamber while the emission of scattered microwave energy is avoided by these necessary openings. To dampen the microwave energy, Both the input section 44 and the output section 46 are with a Pair of flat non-conductive coils 58 provided, the wetter or another contain electrically lossy material, the windings being made of dielectric Material existing tubular cross struts 59 are supported.

Figures 4 and 5 together show a detailed representation of the entrance section 44 of the chamber 43. A slot-shaped opening 61 in the conductive end wall 62 of the chamber 43 provides access for the Veneer sheets and is high enough to avoid difficulties as a result of warping of the Avoid veneer sheets. About the introduction of the luminescent leaves through the slot To facilitate 61, a short bracket 63 extends from this from the outside. One consistently similar slot opening 64 ensures the access of the veneer sheets through the inner heat-insulating end wall 49. Around the passage of the veneer sheets both through slot 61 and through slot 64 to facilitate and pass through by J: To prevent microwave ovens, a beveled edge can be made along the top of each slot electrically conductive lip 66 may be provided, the lips of which extend in one of the conveying direction the direction corresponding to the luminescent leaves and against that of the conveying path the plane defined by the veneer sheets converge. To get the leaflet sheets on your Each support through the slots 61 and 64 extends a flat dielectric Plate 67 between the two along the conveying path. The pair of the filled with water spiral 58 is perpendicularly spaced from one another within the input section 44 arranged, with a helix above the conveying path of the veneer sheets and the others below the conveying path and below the plate 67. The water or others lossy material contained in the coils 58 has the effect of that the microwave energy is absorbed and attenuated, the front slot 64 to Tried to reach slot 61. Only a very small part of this energy becomes parallel to the conveying path of the veneer panels in a way that suits her allows passage from slot 64 to slot 61 without being in coils 58 to penetrate the moisture contained. Most of this energy is in one oblique angle to be directed to the conveying path and repeated between the conductive Walls of the entrance section 44 are reflected before reaching the outer slot 61 is reached, and is consequently multiple - through the merlust-afflicted spirals 58 guided and thereby attenuated. A method of this general kind of suppression of microwave emission through an opening in a multi-mode microwave chamber is detailed in the co-pending application S.N. 589 149 by Morris R. Jeppson, "Apparatus and Method for Microwave Treatment," posted Sept. 7 Filed in 1966 and assigned to the assignee of the present patent application was described.

In Figure 9, the exit end portion 46 is the Karmner 43 as well with electrically conductive walls 47 'and slot-shaped openings 69 and 71 in the end walls, as well as provided with an inner heat-insulating wall 49. In order to guide the veneer sheets into the exit end section 46, upper ones are provided and lower electrically conductive guides 72 arranged in the slot openings 71, which converge in the direction of the conveying path. 'Or extend for the same purpose flat dielectric plates 73 from the upper ones and lower Guides 72 to the top and bottom edges of the slots 69 on the end wall of the exit end section. The pair of water-filled coils 58 of the exit end portion is arranged below and above the dielectric plates 73 to scatter To dampen microwave energy, as described above.

In Figure 4, the waveguide sections 26 and air brushes 29, which cause drying, within the central portion 52 of the chamber between the inner heat insulating walls 49 arranged. Two meandering waveguide arrangements, a first waveguide arrangement 76 and a second waveguide arrangement 77 are arranged along the conveying path of the veneer boards in the chamber 43, wherein the sections of the first waveguide arrangement in Figures 4 to 9 of Drawings are denoted by the reference numeral 26 'and the portions of the second Waveguide arrangement are provided with the reference numeral 26 ″. All waveguide sections 26 'and 26 "of both waveguide arrangements are parallel to and at a distance from one another arranged along the conveying path of the veneer sheets in this penetrating manner.

Advantageous results are achieved by alternating pairs of sections 26 'of the first waveguide assembly 76 having pairs of sections 26 "of the second waveguide arrangement. This arrangement causes a mechanical simple overall construction in such a way that successive sections each of the waveguide assemblies 76 and 77 on the sides of the conveying path of the veneer sheets can be connected by U-shaped side connections 78 and 78 ', which with the first, waveguide sections 26 'and 26 "may lie in one plane some other ways of arranging waveguide sections in a system with a plurality of meandering waveguide arrangements are more complicated interconnection structures necessary on the sides of the arrangements. Some of these arrangements would have to these connecting structures extend, for example, in the vertical direction, to pass above or below adjacent sections of the other waveguide arrangement. Another advantage of this litolgewise of waveguide sections 26 'and 26 " is that the decrease in r / microwave intensity along each waveguide arrangement 76 and 77 from the entry end towards the end opposite this with the decreasing moisture content of the veneer panels is correlated, while the veneer sheets migrate through the dryer. In this way the veneer sheets are made during its narrow from the entrance end to the exit end of the dryer one progressive exposed to decreasing microwave energy intensity. With other types of local arrangement, which multiple meandering waveguide arrays of this general type must necessarily use zones of relatively strong egg wave fields on zones relatively weak energy density follow.

Figure 6 shows together with Figure 4 how the two wave conductor arrangements 76 and 77 through feed sections 79 and 81, respectively, extending from the front end the 'waveguide arrangements on both sides of the conveying path of the veneer sheets, to two separate microwave generators 82 'and 83, as shown in Fig. 3, then, extending upwardly through the top wall 80 of the chamber 43 with microwave energy are supplied. By arranging feed sections for the two Waveguide arrangements 76 and 77 on opposite sides of the conveying path of the veneer sheets at the entrance sections 26 'and 26 ", the gradient becomes the Energy density on the veneer sheets comes into play, along the sections 26 'of an arrangement compensated that reversed, but equally large gradients are present along the sections 26 ″ of the other arrangement and in this way a much more uniform drying effect across to the veneer sheets achieved.

Extending near the exit end portion 46 of the chamber waveguide end sections 84 and 86 up through the top wall 80 of the chamber, around waveguide assemblies 76 and 77 with conventional water-filled waveguide ends 87 and 88, as shown in FIG. 3, to be connected.

In FIGS. 5 and 6, each of the waveguide sections points to j 26 'and 26 "use the slot and lip construction as previously described to create a To allow the veneer sheets to pass through. This includes having the bevel 37 for the passage of the veneer sheets and the wider slot openings 28, through which the veneer sheets emerge from the waveguide sections, wherein the slot openings 28 have the lips 38 described above.

Each waveguide section 26 'and 26 "consists of a lower and an upper individual element 34 or 36, which is along a through the conveying path of the veneer sheets defined plane are divisible, as described above, uni the interior of the waveguide construction to make them accessible, and to expose the scrolls that are transported in them, if that should be desired. To this end, it is extremely beneficial when the upper individual elements 34 - all of the waveguide sections of the lower individual elements 36 can be lifted off simultaneously by i ~ otor hoists. Under simultaneous Referring to Figures 5 and 6 it can be seen that the by efestigung of the upper individual elements 34 of all waveguide sections at one in close proximity above arranged rectangular frame os happens. The all above Single elements the frame 85 carrying the waveguide sections is straight upward in FIG can be raised to a position in which it is just below the top wall 80 of the dryer is, as shown by dashed lines in Fig. 5 at 85 '. The U-shaped side connections 78 are also provided to enable this movement and 78 'interconnecting successive waveguide sections 26' and 26 " connect, divisible along the plane defined by the conveying path of the veneer sheets, so that the upper half of each such connector engages with the frame 85 emotional.

To guide the frame 85 during this movement, four are vertical I-guide rails 89 in chamber 43 in close proximity to the four corners of the frame mounted which extend through passage openings 91 therein. To the up and down movement of the frame 85 is a vertical one in the vicinity of each of the guide rails 89 Spindle 92 is arranged, which is rotatable in a corresponding sleeve 98 of the frame 85 is to move the frame along the guide rails 89 when the spindles to be turned around. Of course, the rotation of each of the four spindles 92 must be careful be coordinated to avoid an escape device and a possible jamming of the frame 85 to avoid. For this purpose, each spindle is on the top 92 mounted above the chamber top wall 80 a gear 94, and all four gears 94 are through a chain 96 which runs through a housing 97 of a drive motor extends on the ceiling of the chamber 43, connected. In FIG. 8, the housing 97 Slots 98 on opposite sides for the passage of the chain 96 through the Case on, and the chain itself runs on a loop that goes through a pair of pulleys 99 and a drive gear 101 is forced. The gear 101 is powered by an electric Drive motor 102 via a speed reduction gear 103 rotated. In this way, the frame 85 and the upper individual elements 34 of the waveguide sections are lifted by actuation of the motor 102 as desired and be lowered.

In particular from Figure 5 it can be seen that the lower individual elements 36 of the waveguide sections are fixedly arranged and on a pair of carriers 104 are attached which extends lengthways through the central portion 52 of the Extend dryer immediately below the waveguide Absohnitten. To remove To facilitate condensed moisture is located between the supports 104 a dewatering vessel 106, which, as shown in Fig. 6, with an outflow opening 107 is equipped, which opens into a drainage channel 108.

As far as the lower bell ladder individual elements 36 are fixed in their position the connection to the feed sections 81 and 86 for the microwave energy are made by wave ladder elbows 109 that are flanged in conventional fashion 111 may have the screws 113 with the lower individual elements 36 of the Initial sections 26 'and 26 "of the two waveguide assemblies can be connected.

The upper individual elements 34 of the initial sections can, however, as already described, lifted upwards, as shown in Fig. 10, or lowered onto the lower individual elements 36, as shown in FIG. 11. This way is the type of connection by means of flanges that was used to to connect the lower individual elements 36 to the waveguide elbow 109 is not applicable on the connection of the upper individual elements 34 with the waveguide knees. One such connection would require the removal of the screws before the top Islelleleiter-single elements 34 could be pulled up, and reinserting the screws after the upper waveguide discrete elements are lowered. Furthermore, the need for such flanges because of a good electrical contact would have to be matched exactly to one another, one require extremely high degree of accuracy of the device, which for raising, lowering and guiding the upper individual waveguide elements 34 is used. To these difficulties to avoid, the upper individual element 34 of each starting section is each of the two waveguide assemblies 76 and 77 are not mechanically connected to the corresponding one Part of the associated waveguide knee 109 is connected and there is a narrow tolerance gap 114, which can best be seen from FIGS. 11 and 12 is. Regardless of the lack of physical contact, electrical contact will be between the waveguide knees 109 and the upper waveguide individual elements 34 by means of a specially designed throttle coupling 112.

A look at the from the joint consideration of Figures 10 to 12 apparent construction of the throttle coupling 112 shows that the upper individual elements 34 of the waveguide sections have a flange 1'16 which is relatively thick Has base 117 in close proximity to the individual waveguide element and further thin has rectangular side projections 118 which are integral therewith and extend normal to the waveguide axis, around a boundary for the above to form tolerance gap 114 described.

To form the opposite delimitation of the tolerance gap 114, a pair of side projections 119 extend sideways from the adjacent end of the waveguide knee 109 parallel to the side protrusions 118. As in particular as best seen in Figure 12, both extend the Side projections 118 of the waveguide section individual element 34 as well as the side projections 119 of the waveguide knee 109 outwards over a length that is slightly greater than a quarter wavelength of the microwave energy transported by the system is.

Each side projection 119 of the waveguide knee 109 has a gap 121, (best seen in Figure 12), the center of which is essentially a quarter wavelength outward from the inner surface of the adjacent wall of the Wollenleiterknies 109 is located. The gaps 121 are made of beads 122 in the Side projections 119 are formed which are parallel to the adjacent ends of the Waveguide elbows 109 extend, and the gaps have a length that is measured from the center of the tolerance column 114, substantially a quarter wavelength beagt. It should be noted that short outer lugs 123 of the side projections 119 extend outwardly a short distance from gap 121 to to match the opposite side projections 118 of the individual elements 34.

The top and bottom of the column 121 are closed and the The flange construction is reinforced on the knee 109 by means of ribs 124 which extend from the Knees above and below the Seitenvorsprun.ge 119 extend outwards and which are attached to it in an electrically conductive manner, for example by soldering. both the side projections 118 and 119 and the ribs 124 are made of electrical conductive material. In this way, both molar gaps 114 and the column 121 is formed and connected by electrically conductive means.

In particular from Figure 10 it can be seen that difficulties thereby slight straight line of escape during the lowering of the movable individual waveguide elements 34 on the lower individual waveguide elements 36 by a run-up tongue 126 avoided extending upward from the end of the knee 109. The casserole tongue 126 has a beveled surface 127 that supports the individual moveable waveguide elements 34 faces and carries a wheel 128 on both sides to the base 117 of the Detect the flange of the movable individual element 34 when the individual element the solid single element 36 approaches. The wheels 128 are above the level of the Flanges of the movable individual elements 116 attached when the movable Single element is in the highest position so that no physical contact exists at that time.

The microwave energy is applied from the knee 109 in the usual manner the attached lower waveguide element 36 transferred by the fact that the flanges 111 establish direct electrical contact between them, and what the currents and field formations in and relates, both form individual elements in Overall effect a unified ladder. Now if you look at the way in which the microwave energy from knee 109 to the upper waveguide elements 34 is passed in spite of the tolerance gap 114 in between, so causes the Formation of the side projections 118 and 119 which contain the column 121 that the flange construction behaves electrically in the same way as a directly conductive one Connection between the knee 109 and the Linzelelement 34 would correspond. the Microwave energy, which is transported along the knee 109, is in the inner part of each tolerance plate 114 coupled; because the tolerance gap is some distance extends outwards, which is greater than a quarter of a wavelength, arise the entrances of column 121} 'eldknobpunkte. Unless the column 121 have a depth which is equal to the size of a quarter of a wavelength, and are limited by electrical conductors 129, the energy in the gaps is more likely coupled than that it is forwarded along the tolerance column 114, where the Impedance is much greater. In this way the conductive connections form 129 along the ends of the gaps 121 short-circuited from the waveguide walls have a distance of half a wavelength and therefore the energy on the Reflect waveguide walls. This actually creates a short circuit connection over the inner ends of each tolerance gap 114 on the inner walls of the knees 109 and the individual waveguide elements 34.

From Figure 4 it can be seen that at the exit end portion each Waveguide arrangement 76 and 77 also have the same specially designed throttle coupling 112 may be provided to attach the end portions 26 of any assembly to the fixed Connect end sections 84 and 86 that extend upward to the waveguide ends 87 and 88 extend, as has already been described above with reference to FIG.

If one considers the construction of the log sheet conveyor in detail with reference to FIGS. 6 and 9, there are close to the luminescent leaf opening 27, upper and lower drive rollers 33 'and 331t, respectively, on each waveguide section 26 parallel to it to support the veneer sheets, as already described and to transport. Both drive rollers 33 'and 33 "are such a pair mounted in forks 131 extending from the supports 1Q4 at the ends of each pair of rollers extend upwards. The lower roller 33 'of each pair is in an associated therewith Fork 131 rotatably mounted about a fixed axis, while the upper Itolle 33 'in vertical slots 132 mounted at the top of the fork is, with the upper rollers changing as required in relation to the thickness variation of the Can raise and lower veneer sheets. Each lower drive roller 33 "has a drive gear 133 on each end and an additional gear 134 on the opposite one End, which is associated with a gear 136 at the corresponding end of the upper Drive roller 33 'karnnit to transmit the rotational energy thereon.

As can be seen in particular from Figure 9, all of the lower drive rollers 33 "is driven by a single continuous chain 137, which is driven by a rflotor 138 is moved, which is located in the exit end portion 46 of the dryer is.

The chain 137 extends from the lilotor 138 along the carrier 104 to a jig 139 in the input end portion 44 of the dryer, wherein slots 141 are provided in the inner heat insulating wall 49 to to let the chain through. The chain runs in the area of the tensioning device 139 via two deflection rollers 142, which are arranged at a distance from one another and which have fixed axes of rotation and the part of the chain that is between the two pulleys, runs over a third pulley 143, which is movable. An adjustable tension spring 144 pulls the pulley 143 down, away from the pulleys 142, around the chain keep under adjustable tension.

The chain 137 runs on each of the forks 131 along the carrier 104 via two spaced-apart pulleys 146, which are above the Chain are arranged, as well as a gear 146 ', which between the pulleys, but above the chain. The gear 146 'rotates coaxial therewith Gear 145, which is connected to a drive gear 133 via a revolving chain 150 connected is.

In the air circulation system of Figure 9, there is a pair of air brushes in the vicinity of the exit slot 28 of each waveguide section 26 for the veneer sheets arranged in the manner mentioned above. In particular are the top air brush line 31 and the lower air brush line 31+ on the upper and lower individual elements 34 or 36 of the waveguide section 26 connected to them on the lips 38 of the exit slots 28, and each has an opening gap 32 to Direct air at the nearby surface of the veneer sheets. As as is clear from FIG. 3, air is pressed into the air brushes by three fans 147, which are arranged along one side of the dryer near its base and are each driven individually by an electric motor 148.

In Figure 6, an inclined 'land t49 separates from heat-insulating material the fans 147 and motors 148 from the inner portion of the dryer and each fan has a suction line 151 extending up through this wall. In this way, each fan 147 draws in air expelled from the air brushes which keeps heating costs to a minimum. As shown in Fig. 3, is between each suction line 151 and the fan connected to it 147 an air heater 152 is arranged, which for example by means of a gas flame 153 can work. Because the oxygen content in the circulating air is reduced in this way can be, each suction line 151 also has an air inlet 155, around the Admission of a certain amount of fresh air to the air heater 152, and support the combustion at 153.

From Figure 6 in particular it can be seen that the heated air outlet 154 of each fan 147 extends through wall 149, to in a manifold 156 running lengthwise through the dryer below the gutter 108 extends.

Line rectangular cross conduit 157 underneath each pair of air brushes 29 transports the hot air from the manifold 156 there. About every such cross line To connect 157 to the associated pair of air brushes, an elbow 158 is on the end opposite the manifold 156. he distributor 156 can supply all of the air brushes from the combined outlets of the three fans 147. However, it is often advantageous to check the air temperature or the air speed or both at different stations along the conveying path of the veneer sheets set different values.

For this purpose, bulkheads 160 can be provided in the distributor, to direct the supply stream of each fan to a separate group of air brushes.

In Figure 7, the lowermost air brush line 31 'of each pair has one angled end piece 159, which is used to connect to the associated Elbow 158 extends downward. The ability to retract the upper air brush line 31, however, requires a clutch with the manifold, which automatically engages and disengages, if there are complications related to the retraction of the upper waveguide element 34, as described, should be avoided. For this purpose the end 161 is the upper air brush line 31 bent downwards and with an enlarged socket end 162 is provided, which has a lip 163 that is bent back. A shaft 164 extends from the bend 158 upwards and from the socket end 162 of the upper air brush line 31 recorded when the air brush is brought into use by lowering it.

About the constant accumulation of moisture in the circulating air circuit a certain part of the length supplied by the fans 147 is to be avoided released from the dryer. From Figures 6 and 9 it can be seen that there are vent lines 166 among the Supports 104 from manifold 156 to a vertical ßntlüftngsschacht 167 extend on the opposite side of the dryer. To control the amount of current delivered by the fans 147, who prefer escaping to the outside than returning to the air brushes is a flap valve 1 & 8 arranged in the ventilation shaft 167.

during operation, the veneer sheets, as from lig. 5 shows fed via the console 63 into the input section 44 of the dryer and through the slots 61 and 64 are fed to the first pair of drive rollers 33. The following Pair of drive rollers then transports the veneer sheets through the next one Pair of waveguide sections 26 and the following pair of air brushes 29. During each passage through a waveguide section 26 becomes inside the veneer sheets very quickly generates noise, which the moisture content to the outside against the surface drifts there. Moisture that settles on the surface of the luminescent leaves in each Waveguide section 26 is accumulated by the subsequent pair of air brushes 29 removed by means of the air flow emanating from these, which also has the It has a positive effect that it applies additional heat to the litouring sheets. The veneer sheets will quietly get drier as they go through the Chamber 43 migrate and eventually exit the dryer between panels 73 of the outlet end portion 46 discharged. As already described, the drying effect is in the moist areas of the veneer sheets proportionally larger that the end product has a uniformly low moisture content.

A control of the degree of dryness to adapt to differences between different batches of fresh veneer sheets and to compensate for others Factors can be done by adjusting one or more operating parameters. One of these the energy input into one or both of the meandering waveguide assemblies 76 and 77, the flow velocity ket the air and the temperature generated by the fans 147 and the air heaters, respectively 152 in connection with the flap valve 168 and the conveying speed controlled by the motor 138 to be determined. The process control is made by a very significant characteristic the procedure described above facilitated. If you pay particular attention to the moisture content of the veneer sheets over time (or the local position in the dryer), sections of rapidly decreasing moisture content alternate with plateaus, along which the humidity remains almost constant Zone of a veneer sheet, which is located on such a plateau, in the further The course only needs to be dried slightly, while lighter zones quickly add to the be brought to the plateau. In many woods, such a plateau occurs when there is a moisture content of around 6 - 7%, and in many cases this is a very suitable moisture content, to join the veneer sheets together to form wood veneer, provided that that the veneer sheets have been treated in accordance with the present invention.

In a practical example performed according to the above method partially dried veneer sheets, in 15 pieces with the dimensions 13720 x 25650 x 2.54 mm from Douglas straightening sent through a dryer according to the invention, in which a succession of 19 spaced waveguide sections from two separate 28 KWatt microwave generators that were fed with one frequency of 915 megahertz worked. The veneer sheets were air currents between successive ones @ tell enl e it is subject to a temperature of 1490 C and a speed, measured in the air brush slots of 15 m / sec.

had. The conveying time of the veneer sheets through the system was 48 Seconds. Before this treatment, the veneer sheets had an average moisture content from 8.1 tv to, with significant fluctuations in different places different Individual pieces of the veneer sheets and considerable fluctuations in the moisture content different veneer sheets, the measured standard deviation being 4.9. Do the drying process as described above, all sheets of veneer had one average ity content of 3.9:; and local differences the moisture content of individual veneer sheets was no more than about +1 with a standard deviation of 0.4 found. It didn't matter to discover falling deterioration of the surface by the process.

latent claims:

Claims (68)

Claims: 1. A method for drying sheet material, thereby It is not noted that the sheet material is raised during its movement a conveying path along a plurality of arranged along the conveying path, im Zones located at a distance from one another are irradiated with microwave energy and Hot air flows along a plurality of spaced apart along the conveying path Zones are directed towards it. 2. The method according to claim 1, characterized in that g e k e n n -z e i c h n e t that the zones along which the micro wave energy is directed to the sheet material is arranged in a line, parallel to one another and running transversely to the conveying path are, and the zones in which the gas streams are directed towards the sheet material, are in line with and parallel to the microwave zones. 3. The method according to claim 1, characterized in that g e k e n n -z e i c h n e t that the intensity of the microwave energy directed onto the sheet material is longitudinal successive Il'örderwegabschnitte steadily decreases. 4. experience according to claim 1, characterized in that g e k e n n -z e i c h n e t that the microwave energy of one of the zones from one side of the conveyor path, and another of the zones from the opposite side of the conveyor path and from coming from a separate source. 5. The method according to claim 1, characterized in that g e k e n n -z e i c h n e t that one sequence of at least seven consecutive microwave zones lengthways of the conveying path of the sheet material is provided, and that the microwave energy from a first source in succession of the first, third, fourth and seventh zone is supplied while from a second source derived microwave energy in succession of the second, fifth and sixth Zone is fed. 6. The method according to claim 1, characterized in that g e k e n n -z e i c h n e t, that the gas streams are directed along zones on the sheet material which are directly behind the individual successive microwave zones, and into them adjacent microwave zones are directed. 7. The method according to claim 6, characterized in that g e k e n n -z e i c h n e t that the gas streams are directed towards the sheet material and arranged in places which are located between the successive microwave zones and are closer to the microwave zones located upstream in the conveying direction than to downstream. 8. The method according to claim 1, characterized in that g e k e n n -z e i c h n e t that the gas streams are hot gas streams, some of which are recovered as circulating air and is used again to coat the lath material. 9. The method according to claim 1, characterized in that E e k e n n -z e i c h n e t that the microwave energy in the successive along the conveying path of the sheet material Zones is preserved. 10. Device for performing the method according to one of the claims 1 to 9, which means that a vertical conveyor for the transport of the sheet material through a multitude of spaced apart and transverse to the Funding weg arranged lell enle iterabschnitt en is provided, which slot openings for the passage of the sheets: have aterials along its conveying path, as well as bushing devices for the gas streams directed at the sheet material, which flow along a plurality of are provided at a distance along the conveying path arranged zones, and that one Energy source for generating the microwave energy for the waveguide sections is provided. 11. The device according to claim 10, characterized in that g e k e n n -z e i c h n e t that the waveguide sections and the gas flow sections are linear and parallel are arranged to each other and enforce the conveying path of the sheet material. 12. The device according to claim 10, characterized in that g e k e n n -z e i c h n e t that the air flow zones are arranged between the waveguide sections and the nozzle means for brushing the sheet material with the gas streams are arranged in these zones so that they gas flows into adjacent waveguide sections direct through their slot openings. 13. The device according to claim 12, characterized in that g e k e n n -z e i c h n e t that the waveguide sections have openings for the exit of the flowing into them Gases, which are small compared to the wavelength of the generated microwaves Have dimensions. 14. The device according to claim 10, characterized in that R e k e n n -z e i c h n e t that the nozzle devices for directing the gas flow onto the sheet material, provided along a plurality of spaced apart zones on one such a place between the liter sections are arranged which is closest to the adjacent waveguide section, which in turn is the Entrance opening for the sheet material in the device ## is closest, where a substantial part of the gas flow is fed into this waveguide section will. 15. The device according to claim 14, characterized in that g e k e n n -z e i c h n e t that each of the waveguide sections has an entry slot opening at the location of the conveying path for the lath material, as well as an outlet slot opening opposite the nise devices for the gas flow directed onto the leaf material, the outlet slot opening wider than the entrance slot opening measured in a direction that is perpendicular to the conveying route. 16. The device according to claim 14, characterized in that g e k e n n -z e i c h n e t that the continuous conveyor for the sheet material has a plurality of drive rollers for driving and supporting the sheet material, each a pair of these drive rollers between successive waveguide sections in the space between the nozzle devices and those following in the conveying direction 7ellenleiterabschnitts is arranged. 17. The device according to claim 10, characterized in that g e k e n n -z e i c h n e t that the nozzle devices provided in spaced apart zones for brushing the sheet material with streams of gas from pairs of tubular air brushes exist, which are arranged between successive waveguide sections are, with the individual tubes of a pair of air brushes on opposite sides of the conveying path are arranged and the air brushes facing the conveying path and have slot openings extending transversely to the conveying direction, which have a Direct high speed airflow against the sheet material. 18. The device according to claim 17, characterized in that g a'k e n n -z e i c h n e t that the air brush is attached to one of the adjacent t: Yellenleiter sections are. 19. The device according to claim 10, characterized in that it is not that the waveguide sections parallel to each other and transversely to the conveying path of the Sheet material are arranged and the continuous conveyor from a pair of drive rollers exists between successive waveguide sections parallel to them are arranged, the individual roles of each pair are arranged so that the Sheet material is contained between them, and the nozzle devices for the gas streams, which are provided along a plurality of spaced apart zones consist of a pair of tubular air brushes placed between successive Waveguide sections are arranged, the individual tubes of each air brush pair are arranged so that the sheet material passes between them, and the Air brushes between a pair of the drive rollers and one of the adjacent panel sections, that is closest to the entry port on the sheet material conveyance path, and each the air brush has a slot opening facing the conveying path and extends transversely to direct a flow of gas onto the sheet material. 20. The device according to claim 10, characterized in that g e k e n n -z e i c h n e t that the energy source for the microwaves consists of two separate generators, one of which is connected to one of the waveguide sections on one side of the conveying path and the other with one of the waveguide sections on the other side of the conveying path is connected. 21. fermentation device according to claim 10, characterized in that g e k e n n -z e.i c h n e t that at least seven successive waveguide sections are provided are and each two waveguide sections with the ends by waveguide connectors are connected together so that they are two electrically separated from each other form meandering waveguide arrangements, the first of which consists of the first, third, fourth and seventh of the successive waveguide sections is formed, and the second of the second, fifth and sixth of the consecutive 7 '{ellenleiterabschnitts is formed, and that the energy source for the microwaves consists of two microwave generators, each with one of the meander-shaped 'tSellleiteranierungen is connected. 22. The device according to claim 21, characterized in that g e k e n n -z e i c h n e t that the waveguide connection pieces are U-shaped and in one plane are arranged with the wave conductor sections. 23. The device according to claim 10, characterized in that it is n -z e i c h n e t that the waveguide sections consist of two separable individual elements, their if plane is essentially in that defined by the conveying path of the sheet material Plane, and that the individual element of each waveguide section from the other can be lifted for itself in a direction perpendicular to the conveying path. 24. The device according to claim 21, characterized in that it is n -z e i c h n e t that a plurality of straight lines extending perpendicular to the conveying plane Guides are provided in which a frame is guided perpendicular to the conveying direction is to which the retractable individual elements are attached, as well as a rotor and gear devices connected to the engine and the frame, 4-around the frame to be able to move in the guides by means of the rotor. 25. The device according to claim 24, characterized in that it is n -z e i c h n e t that the transmission devices of a plurality of themselves parallel to the Guides extending and the frame formed in Wjuffen penetrating spindles rotated by the engine. 26. The device according to claim 23, characterized in that it is n -z e i c h n e t that the nozzle devices for the longitudinally spaced apart Zones to be directed at the sheet material, where gas streams consist of pairs of air brushes, which are arranged between successive waveguide sections, wherein the individual tubes of a pair of air brushes are arranged at a distance from one another, to leave between them a leg for the sheet material, and each individual tube a slot opening facing the conveying path of the sheet material for coating of the sheet material with a gas stream and one of the individual tubes of each pair of air brushes on the retractable individual element of an adjacent waveguide section is attached to be withdrawn with this. 27. The device according to claim 23, characterized in that it is n -z e i c h n e t that the devices for easing the air flow onto the sheet material at least one air brush tube, which is attached to an adjacent one of the retractable Individual elements of the waveguide sections is attached, and with a gas source is connected by means of a self-coupling and self-releasing coupling which from an angled end located on the retractable air brush tube that is aligned in the direction of the retraction process, and one fixed shaft, which with the gas source in coaxial arrangement to the angled End of the retractable air brush tube is connected and into the angled End penetrates when this is lowered to connect with him. 28. The device according to claim 10, characterized in that it is n -z e i c h n e t that at least one waveguide section next to its one end has a waveguide connector is assigned, through which it is acted upon with microwave energy, and the .Telleleiterabschnitt consists of two separable individual elements, which are essentially are separable along the plane defined by the conveying path of the sheet material and one of the individual elements is fixed while the other is withdrawn therefrom can, and the fixed individual element mechanically fixed to the corresponding part of the Corrugated conductor connector is connected and the retractable individual element of the waveguide section from the corresponding end of the waveguide connector separated by a gap, but electrically connected to it by a throttle coupling which consists of a first pair of conductive flanges at the bottom of the retractable Individual element of the -lellenleiterabschnittes and a second pair of conductive Flanges which are attached to the end of the connector, with the first and second pair of flanges spaced apart are arranged to have a tolerance gap delimited by conductive walls to each To form the side of the waveguide section and the multi-conductor connector, which effective lengths of substantially half a wavelength of the emitted f has microwaves. 29. The device according to claim 28, characterized in that it is n -z e i c h n e t that the first and second pair of flanges extend in a direction those perpendicular to the individual elements and connecting pieces connected to them by a distance which is a quarter of the wavelength of the generated microwaves exceeds, and that a gap is provided in at least one of the flange pairs, that by a quarter wavelength from the single element of the waveguide section and the connector is offset outwardly and parallel thereto, and has a length equal to a quarter wavelength of the generated microwaves is, and is delimited at the side and at the end of electrically conductive material, whereby between the waveguide section individual element and the Werbindungs.stück over an actual short circuit is generated across the space separating them. 30. 'Worrichtung according to claim 28, characterized in that g e k e n n -z e i c h n e t that at the end of the connector in the direction in which it is after is retractable at the top, a run-up tongue extends at least one wheel has to guide the retractable single element, to guide when it is the fixed individual element is approached, and which is out of engagement with the retractable learning is when both individual elements are connected to one another -are. 31. The device according to claim 10, characterized in that g e k e n n -z e i c h n e t that at least one of the waveguide sections is a pair of spaced apart having mutually arranged electrically conductive lips, the at least one form its slot openings, and from the Vjellenleiterabschnitt with which they are connected, extend outwards. 32. Apparatus according to claim 31, characterized in that it is n -z e i c h n e t that the lips are located at the slot opening from which the sheet material emerges and converges to a gap, which at his with the part connected to the waveguide section is widest and extends outwards rejuvenates. 33. Apparatus according to claim 31, characterized in that it is e k e n n nz e i c h n e t that the lips extend outwardly a distance which is a quarter of a wavelength corresponds to the generated microwaves. 34. Apparatus according to claim 31, characterized in that it is n -z e i c h n e t that the devices for sifting a gas stream onto the sheet material Pairs of air brush tubes are made up of electrically conductive material and extending transversely to the conveying path of the sheet material and slot openings for directing the flow of air onto the material, a pair of such air brush tubes arranged in the vicinity of the waveguide sections on their lips and with them is electrically connected so that it forms an extension of the lip. 35. Apparatus according to claim 31, characterized in that it is n -z e i c h n e t that the edges of the waveguide section defining the seated opening converge to a common point at each end of the slot opening, and the lips at both ends are angled so that they form part of the converging Edges follow, but stop before the common point of the edges, whereby they do not come into contact with each other. 36. Apparatus according to claim 31, characterized in that it is not e t that the outermost edges of each pair of lips point to the common point of the Slot edges are directed, which is located on the outer surface of the Jand of the Xellenleiterabschnittes is located. 37. Apparatus according to claim 31, characterized in that Z e k e n n -z e i c h n e t that the pair of lips at that slot opening of the '1ellenleiterabschnittes is arranged through which the 3lattmaterial exits and that the slot opening at the entry end of the waveguide section is narrower than the distance between the lips in a direction perpendicular to the axis of the waveguide section lies. 38. Apparatus according to claim 37, characterized in that it is n -z e i c h n e t that the edges of each waveguide section that form the entrance slot opening for the sheet material converge to a common point at each end. 39. Apparatus according to claim 37, characterized in that it is n -z e i c h n e t that the conveying device for the sheet material consists of drive rollers, the between arranged successive waveguide sections and are closer to the waveguide sections that are closer to the exit end of the sheet material from the device lie as the waveguide section closest to the entry end, and which allows the sheet material to pass through the narrow entrance slot openings cause. 40. device; according to claim 10, g e k e n n n z e i c h n e t through a chamber with electrically conductive walls having an entrance end portion and having an exit end portion, as well as electrical conductor portions and devices for directing gas flows onto the sheet material. 41. Apparatus according to claim 40, characterized in that it is n -z e i c h n e t that at least a part of the chamber consists of heat insulating material. 42. Apparatus according to claim 40, characterized in that it is n -z e i c h n e t that in the inlet end portion and in the outlet end portion of the chamber electrical energy-absorbing material is located. 43. Jorrichtung according to claim 40, characterized in that g e zr e n n -z e i c h N e t, since the waveguide section consists of individual elements that run along the Plane formed by the conveying path of the sheet material are separable, u! R to allow free access to the interior of the wave conductors and that the Chamber is provided with access doors in its iand, which are made of electrically conductive Consist of material and electrically conductive directions between the wall and the Have doors to ensure the flow of current in the closed state of the doors. 44. device according to claim 40, characterized in that it is n -z e i c h n e t that the chamber has a valve with an air connection to the outside, as well at least one fan connected to the chamber with a suction line and a first outlet opening for air transport into the device for directing the gas flow onto the sheet material and a second air outlet connected to the valve through which a partial flow can be returned to the sheet material, and another partial flow can be vented to the outside. 45. Apparatus according to claim 44, characterized in that it is n -z e i c h n e t that a variety of fans are provided, each with a separate Group of waveguide sections is connected and that with each of the fans separate air heater is connected, which is separately controllable to air different Temperatures at various points along the path of conveyance of the sheet material onto it to judge. 46. Device for performing the method according to one of the claims 1 to 9, not shown by an i-aar of drive rollers for transport of the sheet material along a flat conveying path, through waveguide sections, which in the next year the drive rollers are arranged parallel to them and Schli.tzöf'fänke along the conveyance path through which the sheet material from the drive rollers is transported through the W.Tellenleiterabschnitts, as well as by a pair of air brush tubes that are parallel to the conveying path and at a distance from each other like that are arranged that the lath material passes between them, and the are located on the side of the 'waveguide section' which is opposite the drive rollers. 47. Apparatus according to claim 46, characterized in that z e k e n n -z e i c h n e t, that the waveguide portion is long that through the conveying path of the sheet material defined level is divisible into two individual elements, and each of the air brush tubes attached to another of the two individual elements s of the waveguide section is. 48. Device for performing the method according to one of the claims 1 to 9, indicated by a first and a second meandering shape .l waveguide array, each of which is a plurality of spaced apart arranged waveguide sections, which extend across the in a plane extending conveying path, with pairs of successive LIYellenleiterabschnitt the first waveguide arrangement with pairs of successive., 'ellenleiter sections alternate the second waveguide arrangement along the conveying path. 49. The device according to claim 48, g e k e n n n z e i c h -n e t through first and second groups of U-shaped waveguide connecting sections, wherein the waveguide connecting sections of the first group are longer and have one have a larger radius than the waveguide connecting sections of the second Group tind the waveguide sections of the first waveguide arrangement through waveguide connectors of the first group on one side of the conveyor path and through all waveguide connection sections of the second group are connected to one another on the other side of the conveying path and the waveguide sections of the second waveguide assembly by waveguide connecting sections of the second group on the first side of the conveyor path and through waveguide connection sections of the first group on the second side of the conveying path with each other are connected. 50. Apparatus according to claim 48, g e k e n n n z e i c h n e t through two microwave generators, one of which each has one of the waveguide arrangements Energy supplied and arranged on opposite sides of the conveying path are. 51. Device according to claim 48, g e k e n n n z e i c h n e t through at least seven waveguide sections, the first - / waveguide arrangement is formed from the first, third, fourth and seventh waveguide sections and the second waveguide arrangement comprising the second, fifth and sixth waveguide sections is formed. 52. Device for performing the method according to one of the claims 1 to 9, characterized in that the waveguide arrangement whose Waveguide sections extend along spaced-apart locations on a flat conveying path, along which the sheet material is transported, extend transversely to this, from at least consists of two separable individual elements, the separating plane of which lies in the li'örderebene and by means for withdrawing one of the separable individual elements the waveguide array can be separated from the other. 53. Apparatus according to claim 52, g e k e n n n z e i c h -n e t through a plurality of linear guides extending in a direction perpendicular to the conveying plane extend, and in which one of the separable individual elements of the waveguide arrangement can slide and is retractable by drive means consisting of at least one rotatable spindle that extends parallel to the guides and with one of the separable individual elements of the Waveguide arrangement in Is engaged and can be rotated by a motor as required. 54. Apparatus according to claim 52, characterized in that it is n -z e i c h n e t that one end of the waveguide assembly by means of a fixed waveguide connecting section is connected to the microwave generator, the retractable single element of the waveguide section a narrow distance from the end of the waveguide connecting section having separate ends, and both electrically to each other by a throttle coupling are connected, which consists of a first electrically conductive flange attached to attached to the end of the retractable single element of the waveguide section and consists of a second electrically conductive flange attached to the end of the waveguide connector is attached and one of the first flange Has spaced a tolerance gap with an effective electrical length of one to create half a wavelength, and that the fixed individual element of the waveguide section and the fixed because of the waveguide connecting portion collide and electrically and are mechanically connected to each other. 55. Device according to one of claims 40 to 54, g e -k e n n z e i c h n e t through a throttle coupling for electrical interconnection a waveguide section having a waveguide connecting section, wherein at least the waveguide section along an axially extending through it Level is so divisible into individual elements, since 3 separate one individual element from the other can be, wherein the coupling consists of a first electrically conductive flange at the end of an individual element of the waveguide section and a second electrically conductive flange at the adjacent end of the waveguide connection section consists, and the first and the second flange are spaced from each other, around a tolerance gap with an effective electrical length of half a length The wavelength of the microwave transmitted through the waveguide sections create. 56. Apparatus according to claim 55, characterized in that it is n -z e i c h n e t that the other individual element of the waveguide section is fixed to the "waveguide connector and is attached to it. 57. Apparatus according to claim 55, characterized in that it is n -z e i c h n e t that a ramp is attached to the waveguide connector to the separable individual element of the waveguide section. lead when it is approaches the other individual element, and the run-up tongue carries at least one wheel, which comes into contact with the separable individual element and leads it, but except Contact with this is when both individual elements of the waveguide section are solid lie on one another. 5O. Apparatus according to Claim 55, characterized in that it is n -z e i c h n e t that the first and second flanges differ from those connected to them Waveguide sections extend outwardly in a direction perpendicular to whose axis is on a length that is a quarter of the wavelength of the ifikrowellen over rises, and that at least one of the flanges has a gap around is offset a quarter wavelength outward from the waveguide section, and which extends longitudinally parallel to the waveguide sections one Length equal to a quarter of a wavelength of the microwave, where the gap is electrically conductive at the side and at the end. 59. Device for carrying out the method according to the claims 1 to 9, indicated by a chamber with electrically conductive walls having an entrance end portion and an exit end portion for the sheet material comprises, and conveyors for transporting the sheet material along a is'örderweges from the inlet end section to the outlet end section, with at least a meandering waveguide arrangement with a large number of Yellenleiter sections, which penetrate the conveying path and longitudinal slots for the passage of the sheet material have, and with electrically lossy material in the entrance and the Exit end section for suppressing microwave emission through these end sections. 60. Device for performing the method according to the claims 1 to 9, g e k e n n n z e i c h n e t by electrically conductive wall elements, which prevent the passage of microwave energy and keep it on one side, with a slit opening, a pair of electrically conductive lips, one of which is longitudinal one edge of the slot and is outwardly outside the Vand extends to prevent the passage of microwave energy through the slot. 61. Apparatus according to claim 60, characterized in that it is n -z e i c h n e t that the lips extend outwardly a distance which is an odd one Is a multiple of a quarter wavelength of microwaves. 62. Apparatus according to claim 60, characterized in that it is e k e n n -z e i c h ne t that the ends of the pairs of lips converge at each end of the slot opening. 63. The device as claimed in claim 62, characterized in that it is n -z e i c h n e t + that the converging ends of the pairs of lips at each end of the slot openings cease to leave a gap between them, which between them does not allows direct electrical contact. 64. Apparatus according to claim 62, characterized in that g e k e n n -z e 1 c h n e t that the converging ends of the pairs of lips at each end of the slot openings run towards a point which is in the plane defined by the wall elements lies. 65. Device for performing the method according to the claims 1 to 9, not shown by a void conductor with longitudinal slot openings along each of the two opposite sides for the passage of sheet material with a pair of electrically conductive lips running along the edges at least one of the slot openings are arranged and from the wave conductor to the outside extend. 66. Apparatus according to claim 65, characterized in that it is n -z e i c h n e t that the lips are arranged on that of the slot openings through which the sheet material emerges from the Yellenleiter. 67. Apparatus according to claim 66, characterized in that it is n -z e i c h n e t that the slot opening through which the sheet material in the Rellenleiter enters, is less wide, measured in a direction perpendicular toill slot lies than the slit opening to which the lips are attached. 68. Device according to claims 65 to 67, g e k e n n n z e i c h n e t through a longitudinal cut running along a wall for the passage of sheet material the edges of which are parallel to one another along a major part of its length and gradually converge at each end of the slot. L e r s e i t e