FI73914B - FOERFARANDE OCH ANORDNING FOER FRAMSTAELLNING AV TRAEMATERIALSKIVA. - Google Patents

Description

1 73914

Method and apparatus for making a wood panel

The invention relates to a method for producing a board of wood material from a press material mat consisting of chipboard and / or fibrous material and a curable binder, e.g. a plastic binder, by pressing within an apparatus for supplying water vapor to the steam generator and a plurality of steam openings distributed on the compression surface portion of the compression surface from which water vapor may escape, the compression mat being placed between the compression plates and the compression plates then then, over a period of evaporation time, through the steam openings 20 of both press plates to the press material mat, whereby further during a certain final compression press cycle, the press plates are driven by further sealing the press material mat to the final position determining the strength of the wood material sheet and the finally sealed press material mat is cured in this final position of the press plates during a certain additional pressing period without supplying further water vapor. The invention further relates to an apparatus for applying such a method, comprising a plate press comprising two vaporizing press plates, a steam generator, a device with a valve-30 for supplying water vapor to the vaporization press plates, a press plate control device and an evaporation control device for supplying water steam, wherein the evaporation press plates have a plurality of steam openings distributed on the press material side of the press plate 7391 4 2. - It is clear that in such a device steam distribution filters can be arranged between the steam openings and the press material mat and / or that the press plates can also be provided on the press material side with porous, e.g. sintered, shut-off plates which allow steam to come out in fine particles. In any case, care has been taken regularly to ensure that high-energy steam rays do not escape from the steam openings, which will damage the mats of compressed material. The compression material mats may be loose or may have been tightly sealed, which does not apply to the pre-sealing of the invention.

A known method in the art (DE patent 12 76 912, Weyerhäuser) uses a continuous, continuous evaporation period of 15 and then supplies superheated water vapor to the press material mat. This water vapor comes out over the edges of the compression mat. The compression material mat plasticizes in this way. After this, the additional supply of water vapor stops and thus also the evaporation period.

20 The plasticized press material mat enters the final seal without additional supply of steam when the press plates are driven into one end position and is cured in this state between the press plates held in the end position. The plate press is then opened again. This has proven to be advantageous in the production of wood material sheets from press material mats, which are a certain composition with easy flow, when superheated water vapor is used and care is taken to ensure that no water vapor condensation enters the press material mats. This requires adequate superheating of the water-30 steam and sufficient temperature of the press plates. Nevertheless, there is room for improvement in the quality of the wood-based panels produced. If the mats of compression material have a lower throughput, then insulating gas cushions are formed in the middle of the plate. This results in 35 less plasticized nests and panels of wood material with more or less inadequate quality. Such nests of insufficient quality are formed in the finished wood material sheets even when water vapor condensation occurs in the compression material mat. Wood material-5 boards with such lower quality nests usually need to be discarded as waste.

The same difficulties occur in a similar method, however, using saturated water vapor (U.S. Pat. No. 43,939,019, Geimer), whereby disturbing condensation of the water vapor 10 is avoided by first heating the press mat using low pre-sealing with water vapor exiting the edges of the press mat. , no more condensate. Thereafter, the impregnated water vapor is fed during the final compaction of the compression mat and thereafter for a predetermined length to the finally compacted compression mat, whereby the water vapor comes out again over the edges of the compression mat and no condensation of water vapor occurs due to said compression temperature. Thus, the uninterrupted evaporation period extends here over the various sealing states of the compression material mat, the compression material mat being subjected to evaporation pre-compacted and finally compacted. Because saturated water vapor is used, condensation can very easily occur. The finished wood panels are therefore often damaged due to the deterioration of the nests due to the fact that either air nests remain in the compression material or condensation has formed.

It is an object of the invention to carry out the method according to the art in such a way that it is no longer possible to produce wood-based panels with lower quality nests, regardless of whether superheated or impregnated water vapor is used. It is a further object of the invention to provide a device with which the method according to the invention can be implemented simply and reliably. Thus, 4,73914 of the method and device according to the invention are characterized in that what is defined in claims 1 and 11.

To solve this problem, the method according to the invention requires that the evaporation period be interrupted by a rinsing press period in which water vapor emerges from the steam openings of the second press plate, flows through the pre-sealed press material mat in the strength direction. continuing to supply water vapor to the finally sealed press material mat through the vapor openings of both press plates for the remainder of the evaporation period, and then during the last pressing period to apply to a specific vacuum source and not to a steam generator. During the first part of the evaporation period of the first 20 before the rinsing pressing period, the press material mat is filled with water vapor, namely until saturation.

In another method of manufacturing wood-based panels, in which the press plates go to their final position before the steam curing begins, it is known (CH patent 463 774, Weyerhäuser) to provide a rinsing-pressing period steam holes. In addition, according to these known measures, the press material mat can be placed on at least one press plate and its steam openings under the effect of a vacuum and dried by means of it.

35 The invention is based on the idea that the disadvantages of the already known procedure in the field are due to the fact that

II

5,73914 Water vapor during evaporation of a pre-compacted and finally compacted press material mat is discharged exclusively over its edge. In this way, it is not possible to avoid small and larger air nests in the compression material, which appear in the finished wood material board as nests of reduced quality. When the water vapor is discharged over the edges of the press material mat to be treated in a known manner, it is no longer possible to carry out, at least to a sufficient extent, evaporation or drainage of the water vapor in the other condensate once it has formed. Also in this way, nests of reduced quality are created in the finished wood material board. This is particularly true in the case of mats of compression material, which are composed in such a way that water vapor can flow through them, 15 but through which the flow does not take place easily. According to the invention, during the rinsing compression period, all the air is made to come out of the compression mat without difficulty by rinsing the pre-compacted compression mat intensively transversely in the strength direction and thus eliminating the deterioration based on air washes. If, within the framework of the measures according to the invention, condensate is formed, this also when the steam supply is switched off, and the water vapor formed from this condensate by post-evaporation is surely removed by transverse transport to and from placed under reduced pressure. In any case, the effect of the vacuum can be arranged to be correspondingly long without difficulty due to the last pressing period. As a result, it is ensured that high-quality boards of wood material are produced, the quality of which has also not deteriorated due to uncured nests.

In detail, the method according to the invention can be further developed in various ways and also optimized. In addition, according to the invention, it is disclosed that the press plates are slowly added together during the first part of the steam kneading period and during the rinsing press period by keeping them in contact with the press material mat. In this way, sheets of press material are obtained, the upper surfaces of which automatically meet all the quality requirements. This supply of water vapor can be continued without interruption through the steam openings of both press plates also during the final compression press period. It is recommended that the mat of compression material be connected to the atmosphere through both compression plates and their vapor openings during the stress relief cycle before being subjected to a vacuum during the last compression cycle. When applying the method according to the invention, a different water vapor pressure is generally used, on the one hand, in the treatment of the pre-compacted press material mat and, on the other hand, in the treatment of the finally compacted press material mat. In this context, a preferred embodiment of the invention is characterized in that the finally sealed press material mat is treated during the rest of the evaporation period with water vapor at a vapor pressure higher than the vapor pressure of the water vapor at which the pre-compacted press mat is.

Superheated steam and saturated steam can be used within the scope of the invention. A preferred embodiment of the invention, which is simple and reliable and stable in applicability, is characterized in that condensable water vapor is used and that the water vapor is condensed during the first part of the evaporation cycle and thus the temperature ° C. In order to achieve this condensation of water vapor, it is only necessary to adjust the water vapor temperature and pressure according to the state diagram of the water / steam system, taking into account the temperature of the compression material in the compression mat and also taking into account the expansion in evaporation. This achieves a very homogeneous temperature distribution. The amount of steam required is determined by the rules of thermodynamics.

The above-described features of the invention as well as the device 5 for applying the method will be explained in more detail below with the aid of drawings. In this case, Fig. 1 schematically shows an apparatus used for applying the method according to the invention, Fig. 2 shows a pressure plate associated with the apparatus of Fig. 1 on a substantially enlarged scale compared to Fig. 1, and Fig. 3 is a graph showing various measures of the method.

The apparatus shown in Figs. 2 for precise control with respect to the position of the closing-20 movement, comprising a pre-sealing position V and a final sealing position E and an evaporation control device 7 for supplying water vapor.

The evaporation press plates 1, 2 have a plurality of steam openings 8, 9 distributed on a part of the press surface on the side of the press material mat. These steam openings 8, 9 may be covered with a fine-meshed metal or plastic mesh, which is not shown. Figure 1 shows a sectional view of a press material mat 10. The evaporation press plates 1, 2 are heated by special heating channels 11, 30 shown in Figure 2. The heating medium flowing through these heating channels 11 cannot escape from the steam openings 8, 9. Steam coming out from the steam openings 8, 9, is fed to the central steam channel 12, from which the distribution channels 13 leave transversely, to which the steam openings 8 and 9 35 enter.

s 73914

The press material mat 10 consists of chip and / or fibrous material and a binder, and by the method according to the invention such a press material mat 10 is made of a high quality wood material sheet, namely by pressing the press material mat for a predetermined time divided into several sections and curing the mat. This takes place between the heated evaporation press plates 1, 2. The compression material mat 10 is placed between the evaporation press plates 10 1, 2 and the evaporation press plates 1, 2 are then driven together by partially compacting the compression material mat 10 during the first pre-compression compression period 8 9 to the compression material mat 10 and further during a certain final compression compression period t, t the evaporation compression sheets 1, 2 are driven together by compacting a further compression material mat 10 to determine the final material compaction position E, during the compression period t5tg without additional steam supply. It is clear that this is accompanied by a period of time t ^ t ^ during which the vacuum is released in order for the plate press to be opened.

The evaporation of the compression material mat 10 and other operations included in the method take place in a specified manner. In this sense, reference is made mainly to Figure 3. In this graph, the time in seconds is denoted as the abscissa.

The left ordinate in Fig. 3 shows the vapor pressure in bars, the right the distance of the upper vapor pressure plate 1 with respect to the lower. The curve of Fig. 3 shows the distance of the upper evaporation press plate 1 from the lower evaporation press plate in 2 millimeters. The dashed curve K2 in Fig. 3 shows the vapor pressure in bars in the lower evaporation press plate 2. The dashed curve K2 depicts the pressure of the vapor il 9,73914 in bars, apart. It can be seen from Fig. 3 that the evaporation period is interrupted by the rinsing press period t2, during which water vapor comes out of the vapor openings 9 of the second evaporation press plate 2, 8. In this connection, the evaporation press plates 1, 2 are driven to the final sealing position E and the supply of water vapor is continued to the finally compacted press material mat 10 through the steam openings 8, 9 of both evaporation press plates 1, 2 for the final period of the evaporation period. Thereafter, the press material mat 10 is exposed to a certain vacuum for the duration of the pressing period t, -tg via both evaporation press plates 1, 2 and their steam openings 8, 9 and is thus dried, for which purpose the device 4 for supplying steam to the steamer is to the vacuum source 14. The period t2t ^ of the rinsing press breaks the evaporation period t ^ t ^ in this way into two parts t ^ 2 3a t ^ t ^. The first part t ^ t2 of the evaporation period t ^ t ^ limits the time during which the pre-compacted press material mat 10 is treated with 25 water vapor. The second part t3t4 of the evaporation period t1t4 again limits the time during which the finally compacted press material mat 10 is treated with water vapor, the steam supply also taking place during the final sealing pressing period t3tx, which must therefore be counted as part of the second evaporation period.

Figure 3 also shows from the descending direction of the curve part 18 that the evaporation press plates 1, 2 slowly move further together during the first part t ^ t ^ of the evaporation time period t ^ t ^ and the chicken of the rinsing press period t2 ^ ai-35 by keeping in contact with the extrusion material mat 10. under the effect of a vacuum, the stress is removed, namely, by pressing the press material mat 10 into the atmosphere through both evaporation pressure plates 1, 2 and their steam openings 8, 9 during the stress relief compression period 5 ^ 4 ^ 5. The final compacted press material mat 10 is treated during the remainder of the evaporation period t ^ t4 with a water vapor having a pressure higher than the water vapor pressure at which the pre-compacted press material mat 10 is treated.

10 In the structural example, condensing, eg slightly superheated, steam is used. The method is applied in such a way that the condensing water vapor condenses in the press material mat 10 during the first part t ^ 2 of the evaporation period t ^ t4 and during the rinsing press period t2 ^, whereby the temperature of the press material 10 comes very homogeneously by condensation about 100-135. C. Thereafter, it is appropriate to use uncondensed steam.

In order to be able to carry out the described operations without difficulty, in particular also under computer control, the steam supply device 4 has, as shown in Fig. 1, a branch line 15 which can be connected to both evaporating pressure plates 1, 2 by means of 1 during the rinsing press period t2 ^ and during the period t4t <of both press plates 1, 2 to the surrounding atmosphere and during the last control period t, -tg of both evaporation press plates 1, 2 to a specific vacuum source 7 is connected. The device is arranged so that the evaporation control device 7 also controls the steam supply during the rinsing compression period t2t3 as well as the stress relief during the stress relief compression period t4t ^ 35 and the vacuum treatment during the compression period t1t3. When the pre-sealing position ti 11 7391 4 V is reached and when the final sealing position E of the evaporating press plates 1, 2 is reached, the control signals 6 supply control shafts to the evaporation control device 7, which causes said steam supplying operations. ai ^ ana 3a for the remainder of the evaporation period t ^ t4.

Otherwise, the device is arranged so that the pressure plate control device 6 and the evaporation control device 7 can be controlled between the pre-sealing position V and the final sealing position E and thereafter on a program-by-program basis.

The graphic representation of Fig. 3 relates in detail to the production of certain panels of wood material from press material mats 10 made specifically for this purpose. In this case, the construction is made of press material mats and wood material boards mentioned in claim 7. For the production of these 15 press mats 10 and thus for the production of said wood-based panels, it is expedient to use, as can be seen from Figure 3, a press time of 20-50 seconds, and in which the evaporation period t ^ t4 is arranged at no more than two thirds of the first evaporation period t ^ t2 is less than 10 seconds, preferably about 5 seconds, until the start of the rinsing-pressing period tjt ^, the rest of the evaporation period t ^ t ^ being shorter than the difference between the evaporation period t ^ t4 and its first part t ^ t2. This is due to the interruption of the steam-25 knuckle period t ^ t4 caused by the rinse-press period t2t ^, which lasts less than 5 seconds, preferably about 2 seconds. The final compaction period t ^ t is added to the rest of the evaporation period t ^ t4 ·

Claims (15)

A method of producing a wood material board from a press cargo mat (10), which is made up of tension and / or fiber material and a curable binder, e.g. a synthetic resin binder, by pressing during a predetermined, divided into several press time sections and by curing with water vapor between heated press discs (1,2) in a disc press, said press discs having a device for supplying water vapor from a steam generator (3) and on the press cargo mat side, a plurality of meadow openings distributed over the press, from which water vapor may protrude, whereby the press cargo mat is inserted between the press discs and the press discs in a first precompressing press time section, which is advanced to a precompression position, whereupon a suspension time section is inserted into the press cargo mat through the meadow openings (8,9) in both press discs (1,2), and further in a final compressive press time section the press discs are further compressed to a thickness of the wood material disc defining the final material and final finishing material compressed cargo mat in this final position of press the discs are cured in a further press time section without further supply of water vapor, characterized in that the suspension time section (t ^ t ^) is interrupted by a flush press time section (t ^ tj), whereby water vapor exits from the meadow apertures (9) in one press disc (8), the pre-compressed compression mat (10) flows in the thickness direction and is diverted via the meadow openings (8) in the second disc disc (1) which is disconnected from the water meadow source (3), that in connection with this the press discs (1,2) are driven to the final position. (E), that the water vapor supply to the final compressed press cargo mat (10) via the meadow openings (8,9) in both press discs (1,2) may continue for the remainder of the suspension time section (t ^ t ^) * and then during the last The press time section (t ^ t ^) is subjected to a negative pressure via at least one of the two press discs (1,2) and its mole openings (8,9) and thereby dried, for which purpose the device (4) water supply a single one (instead of a water meadow generator (3)) is connected to a negative pressure source (14). 2. A method as claimed in claim 1, characterized in that the pressing discs (1,2) under the first section (t2t2 ^ of the uPP ^ n9nin9sti (t ^ t ^) and during the coil pressing time step (tt is moved towards each other during contact of the press cargo mat (10). Method according to any one of claims 1 or 2, characterized in that the water vapor supply at the meadow openings (8,9) in the two press discs (1,2) is continued continuously during the final compressive press time section (t ^ t ^). Method according to any one of claims 1-3, characterized in that the press cargo mat (10) is connected to the atmosphere during a relaxation time section (both) via the two press discs (1,2) and their meadow openings (8,9). ) before it is subjected to the influence of the vacuum in the final press time section (t ^ tg). Method according to any of claims 1-4, characterized in that the final compressed cargo mat (10) during the ether (t ^ t ^) of the suspension time section is treated with water vapor, the pressure of which is higher than the pressure of the water vapor supplied under the longer part of the suspension time. Method according to any one of claims 1-5, characterized in that it works with condensable water vapor and that the water vapor during the first part (t Is condensed into the pressurized mat (10), thereby setting the temperature of the pressurized mat (10) to about 100-135 ° C. 35 Process according to any one of claims 1-6 in an embodiment for producing wood material sheets with urea-formaldehyde glue, a moisture content in the press cargo mat of about 8% and a straightness in a loosely structured press material rate of about 390 kg / m, characterized in that it operates with a pressing time of about 20-50 seconds, that the suspension time (t ^ t ^) is focused on a maximum of two-thirds of the pressing time (tgt ^), that the first section of the suspension time reaches the beginning of the coil The press time section 2 2 ^) has a duration of less than 10 seconds, preferably about 5 seconds, and the spool press time section 10 has a duration of 5 seconds, preferably about 2 seconds, and that the last section (t ^ t ^) of the suspension time is shorter than the first section of the suspension time (t ^ t ^). 8. A method according to claim 7, characterized in that water angling is also performed during the final compressive pressing time section (t, t). Method according to any of claims 7 or 8, characterized in that it operates with a water vapor having a temperature of about 100-175 ° C. 20 Method according to any one of claims 7-9, characterized in that during the first section of the heating time the water vapor is measured to the pre-compressed press cargo mat (10) at a pressure of 1.5-3.0 bar and during the resting period of the suspension. Time to the final compressed cargo mat (10) at a pressure of 3-9 bar, in each case according to the nature of the binder. An installation for applying the method according to any one of claims 1-10, comprising a disc press having two meadow-treating press discs (1,2), a water meadow generator (3), a device for feeding the water vapor to the ang-treating press discs, which provided with valves, a pressure washer control device for precise position control of the closure movement of the meadow treatment presses with a defined pre-compression position and defined final compression position, and a control device for supplying the water vapor for the meadow treatment. treating press discs on the press cargo mat side (10) show a plurality of angular openings (8,9) distributed over the press discs (1,2), characterized in that the water vapor supply device (4) has a branch line , which can be connected via the outlet valves (16) to the two meadow treatment press discs (1,2), and that the branch line (15) via a branch valve device (17) under the reel press time section (2) for the portion of one meadow press (9) and during the relaxation press time section (t 2) for both of the meadow press (1,2) parts may be connected to the the surrounding atmosphere and during the last press time section (t ^ t ^.) of the two meadow-processing press discs (1,2) to a pressure source (14). 12. Plant according to claim 11, characterized in that the pressure washer control device (6) and the control device (7) for the meadow treatment are coupled. Plant according to any one of claims 11 or 12, characterized in that the meadow control regulator (7) also controls the meadow supply during the flush-press time section (t ^j) and also the suppression treatment during the last press-time section (t5tg). Installation according to any one of claims 11-13, characterized in that the control disc (8) emits the control device (6) upon reaching the pre-compression position (V) and upon reaching the final compression position (E). (7) for the meadow treatment, which activates the specified meadow maneuvers during the first section of the uptime (t t t ^) and during the remainder of the uptime (t ^ t ^). Plant according to any of claims 11-14, characterized in that the press disc control device (6) and the meadow treatment control device (7)