Apparatus and method for continuous production of materials

Abstract

An apparatus and method for the continuous production of materials, preferably for producing material boards made of essentially non-metallic material, comprising a continuous furnace (1) for continuously heating material (3) on an endlessly circulating conveyor belt (10) and a press (2) provided downstream in the production direction (15), wherein the continuous furnace (1) comprises a plurality of magnetrons (4) for generating electromagnetic waves and hollow conductors (5) with outlet openings (6) for feeding the waves into a radiation chamber (14). The invention is intended to solve the problem of reacting to various operating modes for the continuous furnace and, in particular, to heat up the material used in the best possible manner for later pressing. The invention is characterized in that a control or regulating apparatus (17) is arranged for controlling individual or grouped magnetrons (4) in order to provide them with different powers (L) for producing a differentiated power profile (9), preferably in and/or transversely to the production direction (15). (1491)

Claims

1. A method for the continuous production of material boards made of essentially non-metallic material, comprising: continuously heating material on an endlessly circulating conveyor belt via a continuous furnace; providing a press downstream in a production direction; generating electromagnetic waves via a plurality of magnetrons included in the continuous furnace; feeding the electromagnetic waves into a radiation chamber via hollow conductors with outlet openings; and controlling individual magnetrons or the plurality of magnetrons to operate the magnetrons with different powers for a differentiated power profile in and/or transversely to the production direction.

2. The method according to claim 1, wherein the magnetrons are controlled by a control or regulating apparatus.

3. The method according to claim 2, wherein the control or regulating apparatus is configured for retrieving and setting predetermined power profiles based on the material, a construction of the material and/or a product to be produced.

4. The method according to claim 2, wherein the material and/or a product is checked by at least one measuring apparatus, and the corresponding measured values are transmitted to the control or regulating apparatus for controlling or regulating the magnetrons or the power profile.

5. The method according to claim 2, further comprising determining a speed of the conveyor belt via a drive of the conveyor belt or a measuring apparatus, and the determined speed is transmitted to the control and regulating apparatus and used to calibrate a power cycle and/or a utilization cycle of the magnetrons against a feed of the material.

6. The method according to claim 2, wherein the control or regulating apparatus is configured to automatically monitor or detect the magnetrons or their power consumption, and automatically activate necessary power or further magnetrons.

7. The method according to claim 2, wherein the control or regulating apparatus is configured to apply higher power to local surface weight increases in the material occurring transversely to the production direction via a path/time tracking, and to control the magnetrons for such a purpose in a corresponding temporal and geometric arrangement.

8. The method according to claim 1, wherein the magnetrons are operated at a power of 0.5 to 20 kW.

9. The method according to claim 1, further comprising deactivating a passive and/or active distributor in the radiation chamber for the electromagnetic waves during heating of the material with different powers of the magnetrons.

10. The method according to claim 1, wherein a power profile of the magnetrons is set transversely to the production direction, which sets a higher temperature of the material from edges to a longitudinal center line of the material.

11. The method according to claim 1, wherein the magnetrons are arranged in a plurality of rows and tracks, and in an event of failure of a magnetron, one or several other magnetrons of associated and/or adjacent tracks compensate for the failure by increasing their power, or, in a case of maximum power of the magnetrons, the failure is compensated for by switching off a whole row of magnetrons and reducing a speed of the conveyor belt correspondingly.

12. The method according to claim 1, wherein the magnetrons are arranged in a plurality of rows and tracks, and wherein at different widths of the material and/or varying positions of the material on the conveyor belt, at least one track of the magnetrons arranged on an edge is correspondingly switched off or reduced in power.

13. The method according to claim 1, wherein, in order to increase redundancy, additional magnetrons that are not used in regular operation are provided, the additional magnetrons being configured to switch on in the event of a magnetron failure.

14. A method for the continuous production of material boards made of essentially non-metallic material, comprising: continuously heating material on an endlessly circulating conveyor belt via a continuous furnace; providing a press downstream in a production direction; generating electromagnetic waves via a plurality of magnetrons included in the continuous furnace; feeding the electromagnetic waves into a radiation chamber via hollow conductors with outlet openings; and controlling individual magnetrons or the plurality of magnetrons to operate the magnetrons with different powers for a differentiated power profile in and/or transversely to the production direction, wherein a corresponding power profile of the magnetrons is activated transversely to the direction of production in a material with a different surface weight profile over a width, and wherein regions of different surface weights are subjected to different powers of the electromagnetic waves.

15. A method for the continuous production of material boards made of essentially non-metallic material, comprising: continuously heating material on an endlessly circulating conveyor belt via a continuous furnace; providing a press downstream in a production direction; generating electromagnetic waves via a plurality of magnetrons included in the continuous furnace; feeding the electromagnetic waves into a radiation chamber via hollow conductors with outlet openings; and controlling individual magnetrons or the plurality of magnetrons to operate the magnetrons with different powers for a differentiated power profile in and/or transversely to the production direction, wherein the material comprises wood or wood-like material with a different surface weight profile over a width thereof, and wherein the magnetrons with outlet openings essentially above areas of higher surface weight are operated with a higher power than the magnetrons with outlet openings above areas of lower surface weight.

Description

(1) With reference to the accompanying drawings, details and exemplary embodiments of the invention are explained in more detail, wherein the drawings show as follows:

(2) FIG. 1 shows a schematic side view (top) and an associated schematic view (bottom) of an apparatus with a strand of material, which is guided in the production direction through a continuous furnace and a double-belt press,

(3) FIG. 2 shows a top view of the cover of the radiation chamber of the continuous furnace with an exemplary arrangement of the hollow conductor,

(4) FIG. 3 shows a section X3 in the production direction according to FIG. 2 through the radiation chamber, and

(5) FIG. 4 shows an exemplary representation of a power profile for producing a material board of lignocellulosic material and corresponding edge cut-off of the outside rows of magnetrons.

(6) FIG. 1 shows at the top a schematic side view and at the bottom a corresponding schematic top view of an apparatus with a steel strip running in the production direction 15 through a continuous furnace 1 and a continuously operating press 2 with two endlessly circulating steel strips which pull the strand-like material 3 through the press 2. The material 3 is transported in this case on the conveyor belt 10 from the left through the continuous furnace 1, where it is heated in a radiation chamber 14, transferred to the press 2 and is pressed and cured there into a product 8.

(7) Depending on the embodiment of the apparatus, a radiation chamber 14 can be arranged for a higher efficiency not only from an upper or lower surface side, but the material 3 can also be subjected with microwaves from the other surface side in a radiation chamber 14′. This may especially be necessary if the penetration depth of the microwaves from one side does not sufficiently heat through the material 3 or if the power for heating is to be increased. In addition to a shielding housing 11, the continuous furnace 1 also has absorbers 12 around the radiation chamber 14, which absorb excess microwaves on the inlet and outlet sides and, in addition to the gates only indicated there, prevent the emergence of microwaves from the continuous furnace 1. The gates and/or the absorbers 12 are designed to be height-adjustable and/or width-adjustable for adaptation to different heights and widths of the continuous material 3.

(8) The apparatus according to the invention has a control or regulating apparatus 17, which is capable of controlling the plurality of magnetrons 4 for the purpose of producing microwaves with respect to their power. In particular, it is provided that the control or regulating apparatus 17 can control individual or grouped magnetrons 4. The control or regulating apparatus 17 is preferably operatively connected to a storage apparatus and/or a computing unit which already contains recipes or predetermined frame data for setting the continuous furnace 1 or the magnetron 4. In particular, calculation bases can be stored here, on the basis of which the control or regulating apparatus 17, in conjunction with inputs from the operating personnel, realises proposals or settings with respect to the type of the material 3 and/or the product 8 to be produced, with which the continuous furnace 1 can operate in conjunction with the downstream press 2 in an optimum range which is harmless for the material 3.

(9) In an alternative or combined embodiment, measuring apparatuses 16 can be arranged in the production direction 15 upstream of the continuous furnace 1, and measuring apparatuses 18 downstream of the continuous furnace 1 and upstream of the press 2 for the material 3. Alternatively or in combination, it can be provided to arrange a measuring apparatus 20 for the product 8 at the outlet of the press 2. It is common to all of these measuring apparatuses, or possibly further measuring apparatuses, that they can be in operative connection with the control or regulating apparatus 17 and can transmit their measuring results thereto. These measurements form the basis for control or regulating algorithms and cause the generation and transmission of corresponding control commands in the control or regulating apparatus 17 to the continuous furnace 1 or the magnetron 4 arranged there.

(10) Alternatively or in combination, further upstream apparatuses of the production facility or the control station of the system for transmitting data can be in operative connection with the control or regulating apparatus 17.

(11) These measuring apparatuses 16, 18, 20 may preferably be suitable for measuring the width 19 of the material 3 or of the product 8 in sections.

(12) As is further shown in FIG. 1, the material 3 is applied to the conveyor belt 10 in a height which is small compared to the width 19. Preferably, the material 3 is pressed in this width 19 in the subsequent press 2 to the product 8. The material 3 is thus preferably strand-shaped, in this case having an upper and a lower surface side, wherein one surface side rests on the conveyor belt 10 and forms two edges 7. The position of the edges 7 on the conveyor belt 10 is varied in accordance with experience, in particular by the belt course during the application of the material 3 onto the conveyor belt 10, by changes in trimming or product changeover. The subsequent course of the belt in the region of the continuous furnace 1 can also lead to consequence that the conveyor belt 10 is not always guided through the continuous furnace 1 in the same position.

(13) FIG. 2 shows a top view in the production direction 15 from the bottom upwards on the cover 22 of the radiation chamber 14 in a section X2-X2 from FIG. 3. FIG. 3 shows the corresponding view of a section X3-X3 through the radiation chamber 14 according to FIG. 2, wherein the production direction 15 is directed into the drawing plane.

(14) The following embodiment of the radiation chamber 14 is obtained from the combination of the two FIGS. 2 and 3. The magnetrons 4 are preferably arranged separately in a cabinet 13 and to the side of the radiation chamber 14 for better accessibility, in particular for maintenance or replacement purposes. The cabinet 13 has openings through which the hollow conductors 5 connected to the magnetrons 4 conduct the microwaves to the radiation chamber 14 and enter the radiation chamber 14 there via the outlet openings 6, corresponding to openings in the cover 22. In the top view it can be seen that the outlet openings 6 are arranged in a plurality of rows R (R.sub.n, R.sub.n+1) transversely to the production direction 15 and tracks S (S.sub.n, S.sub.n+1) longitudinally to the production direction 15.

(15) The manner in which the outlet openings 6 are arranged on the radiation chamber 14 depends on the use of the continuous furnace 1, the frequency of the microwave radiation which has an influence on the size of the hollow conductors 5 and thus on the outlet openings 6, and in particular also on the type and the volume of the material to be heated 3. It can therefore be possible to use only a small number of magnetrons 4, wherein at least two thereof must be arranged. These then form a row in any direction. However, it is preferably provided that at least a plurality of magnetrons 4 is arranged in a row R and can be controlled by means of the control or regulating apparatus 17 with a differentiated power profile 9. Already one row R, possibly but not necessarily transversely but angularly (except parallel) to the production direction, enables the differentiated heating of the material 3 across the width 19.

(16) In particular, with a corresponding arrangement and/or alignment of the outlet openings 6 of the hollow conductors 5, a differentiated heating profile in the material 3 or a differentiated power profile 9 of the magnetron 4 can be controlled. The possibilities for this are manifold.

(17) According to FIG. 3, a second radiation chamber 14′ can be provided, opposite the first radiation chamber 14 with respect to the material 3 and thus arranged below the conveyor belt 10. It can preferably have the same configuration concerning magnetrons/hollow conductors/outlet openings as the radiation chamber 14. The material 3 to be heated here has a predetermined width 19 and rests on the conveyor belt 10 passing through the continuous furnace 1. The material 3 is essentially of an strand-like configuration, has two surface sides and a respective edge 7.

(18) Use of a single track S with in each case one outlet opening 6 per row R: It is possible to control the material 3 in the production direction 15 with differentiated powers L, e.g. a rising power scale (R.sub.1=20%, R.sub.2=40%, R.sub.3=60%, R.sub.4=80%, R.sub.5=100% at at least 5 rows). This may be advantageous if the material 3 is present, for example in a supercooled or frozen manner and, if appropriate, has been impregnated with water. Alternatively, the power scale can also be used vice versa if first a strong heating and then a homogenisation of the heat in the material 3 with a lower microwave intensity is to be supported.

(19) Use of a single row R with a respective outlet opening 6 per track S:

(20) It is possible to control the material 3 transversely to the direction of production 15 with differentiated powers L, for example a heating which increases from the edge 7 of the material 3 to the longitudinal centre line 21 (S.sub.1=25%, S.sub.2=50%, S.sub.3=75%, S.sub.4=50%, S.sub.5=25% at at least 5 tracks). As already mentioned above, the possibilities are manifold and not all of them are finally described.

(21) Use of a plurality of rows R.sub.n, R.sub.n+1 with exit opening 6 and several tracks S.sub.n, S.sub.n+1 according to FIG. 2:

(22) Very complex power profiles L can be set in and across the production direction. Thus, in a 3D view, a three-dimensional power profile is obtained by setting different powers in different magnetrons 4. In particular, for the optimised heating, the space-time component and the heating degree together with the throughput speed during heating or in the control or regulating apparatus 17 should also be taken into account.

(23) In a simple exemplary embodiment according to FIG. 4 for a power profile 9, a material 3 of a width 19 is conveyed through the radiation chamber 14, as shown in FIG. 3. According to FIGS. 4 and 2, the number of tracks S is equal to 16. Due to the possibility of controlling all the magnetrons 4 individually or in groups, the magnetrons 4, which are in operative connection with the outlet openings 6 of the tracks S.sub.1, S.sub.2 on the left and S.sub.15, S.sub.16 on the right, are deactivated and have a power L=0%, since they are arranged directly above a region which is not occupied by the material 3. In order to ensure that the edge region of the material 3 is heated only slightly, the magnetrons 4 of the tracks S.sub.3, S.sub.4 on the left and S.sub.13, S.sub.14 on the right of the outlet openings 6, which are arranged on the edge 7 of the material 3, are operated with only half the necessary power L=40%. The regions of the material 3 lying further inward of the longitudinal centre line 21 are subjected to a power L=80% of the magnetrons and are heated accordingly. For this simple application, the subsequent rows can accordingly represent the same power profile 9, as shown in FIG. 4.

(24) Advantageously, the use of a plurality of rows R and tracks S is possible in a method for protecting the magnetrons 4 by alternately switching the magnetrons 4 on and off. Switching on and off does not describe the power cycle, which is usually used to adjust the power L of a magnetron, but the pause of the magnetrons is provided to maintain the performance capabilities and to avoid overheating, i.e. a usage cycle.

(25) In a simple, plausible example, the continuous furnace could be operated as follows:

(26) When calculating the necessary power for heating the material to a predetermined temperature, the necessity arises, when all the available magnetrons 4 are used, to operate them at 35% of the rated power, wherein it is assumed for the sake of simplicity that all magnetrons 4 would operate with the same power L. It is now determined that with an arrangement of the outlet openings 6 as in FIG. 2, n=6 applies to R.sub.N and S.sub.n. Thus, there are 36 exit openings 6 for six rows R and six tracks S. In order to protect the magnetrons 4, a running operation is now proposed in which the magnetrons 4 of all tracks S are used, but the rows R with even n and the rows R with odd n are alternately switched on. For this purpose, the rated power of the active 18 magnetrons 4 (36/2) is doubled so that they are operated with a nominal power of 70%. An unnecessary continuous operation of the magnetrons 4 is thus avoided.

LIST OF REFERENCE NUMERALS

(27) 1 Continuous furnace

(28) 2 Press

(29) 3 Material

(30) 4 Magnetron

(31) 5 Hollow conductor

(32) 6 Outlet opening

(33) 7 Edge

(34) 8 Product

(35) 9 Power profile

(36) 10 Conveyor belt

(37) 11 Housing

(38) 12 Absorber

(39) 13 Cabinet

(40) 14 Radiation chamber

(41) 15 Production direction

(42) 16 Measuring apparatus

(43) 17 Control or regulating apparatus

(44) 18 Measuring apparatus

(45) 19 Width

(46) 20 Measuring apparatus

(47) 21 Longitudinal centre line

(48) 22 Cover

(49) R Row of outlet openings transversally to 15

(50) S Track of the outlet openings in 15

(51) L Power of 4