FI127449B - Method and device for pre-drying a wood veneer bundle by pressing - Google Patents

Abstract

Procedure for pre-drying a veneer stack by pressing. In the process, at least twenty turned veneer sheets are collected on top of one another in a veneer stack. At least part of said veneer stack is arranged between a first and a second plane surface. In the method, at least the first surface is moved toward the second surface and / or the second surface to the first surface to subject the veneer bundle to a pressing and pre-drying of the veneer bundle by pressing so that the veneer bundle is exposed to the surface pressure through said surfaces, which surface pressure is below at least 2 seconds at least 1 bar and not more than 13 bar and then above 13 bar for at least 150 seconds for one or more periods and not more than 100 bar. Further, a device for pressing a veneer stack.

Description

Method and apparatus for pre-drying a bunch of wood veneer by compression

Object of the invention

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The invention relates to pre-drying wood veneers by compression. The invention further relates to the manufacture of wood veneers. The invention further relates to drying wood veneers. The invention further relates to an apparatus suitable for pre-drying veneer veneers.

Background of the Invention

Dry wood veneers are commonly used in the manufacture of wood products. For example, in the manufacture of plywood boards, dry wood veneers are stacked crosswise in the fiber directions, and by gluing and squeezing, the wood veneers are pressed into plywood boards. Dry wood veneers are also used in the manufacture of parquet.

Veneers are made from wood by any known method, such as turning. Wood used in veneer production is not completely dry because it is difficult to turn dry wood. As a result, the turned veneer is relatively20 its moist.

Wood veneers have long been dried at high temperatures with hot drying gas. This process consumes considerable amounts of energy. One new and more energy efficient way to dry wood veneers is to feed them individually by means of two rollers between two different heat surfaces, the first of which is hot, typically above 120 ° C and below 200 ° C, and the other is about 50 ° C cooler. In addition, the rolls and / or said surfaces can be used to compress some of the individual veneers as they are dried by heat and temperature difference. However, there are problems with such drying. Since at least one of the surfaces is hot, significant amounts of energy are consumed for heating. In addition, passing the veneers one by one between the sheets is quite slow.

BRIEF SUMMARY OF THE INVENTION

It has been found that wood veneers can be pre-dried in a bundle and in a plane without significant heating. In this case, a plurality of wood veneers are pressed substantially simultaneously over their entire surface. Compared to heat drying alone, the time savings are many times because multiple veneers can be treated at once and water can be squeezed all over the entire veneer (i.e. veneer sheet) area. In addition, energy savings are significant as no special heating is required. According to preliminary results, however, in such a process, the wood veneers may break and / or have reduced mechanical properties. For example, at too high a pressure, the cellular tissue of the wood may break, causing the wood to weaken. In addition, too high a pressure of water at too high a pressure can disrupt the tissue of the wood. Correspondingly, too little pressing does not say pre-dry the wood. In addition, it has been found that a small pre-compression before the actual compression reduces cracking of the wood veneers. Possibly, this is because the wood veneers are able to straighten sufficiently under a sufficiently low pressure. In addition, a device has been invented for drying wood veneers in wood veneers as described above.

The process according to the invention is described in independent claim 1 and example 1.

The pressing is carried out with a suitable device. One such device is described in independent claim 11 and example 21.

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Brief Description of the Drawings

Figure 1 is a side elevational view of pre-drying wood veneers by squeezing in a press, Figure 2 is a perspective view of a press suitable for pre-drying wood veneers; weekly (i.e.

Wood Veneer); Fig. 4 shows the amount of water pressed in one experiment, Fig. 5 shows the moisture content of the veneer in one experiment, and

20155433 prh 08 -06- 2015 Figure 6 shows a process for making dry wood veneers.

Detailed Description of the Invention

Method

Figure 1 illustrates the pressing of wood veneers 102. Wood veneer can be, for example, turned, cut or semi-turned, by all means economically making wood veneer. Wood veneer 102 in this application is intended to be a wood veneer made by turning because sufficiently large wood veneers 102 are easily turned to form large, sufficiently stable and movable wood veneer bundles 110 that can be pre-dried by compression. As shown in Figure 1, a plurality of turned wood veneers 102 are arranged in a bundle of wood veneers 110. Pre-pressing by compression is particularly suitable for drying relatively moist wood veneers 102. Wood veneer bundle 110 comprises at least twenty wood veneer. However, the time savings achieved by the method and the equalization of moisture can be more effective in large bundles. Typically, the wood veneer bundle 110 comprises hundreds of wood veneers, for example, such that the height of the wood veneer bundle is at least 500 mm, such as at least 1000 mm.

Preferably, the wood veneer bundle 110 is formed of wood veneer 102 which is quite moist. Each veneer consists of moisture and dry matter. Thus, for example, a plurality of wood veneers from the lathe comprises moisture and dry matter. In one embodiment, wood veneers 102 are pre-dried which together contain moisture of mass m _w and total contain dry matter of mass m _d . For example, in the case of spruce, pre-drying is preferably performed on a plurality of veneers in which the ratio of moisture mass to mass of dry matter, m _w / m _d , is at least 60%. Preferably, this also applies to the wood veneer bundle 110. For example, in the case of birch, pre-drying is preferably performed on a plurality of veneers in which the moisture mass and dry weight mass fraction, m _w / m _d , is at least 45%, such as at least 50%. Preferably, this also applies to puuviilunippua 110. Before the pre-drying moisture puuviilunippu 110 includes a mass, m, and _{w b} amount of powder mass M _{d B} in such a direction that the humidity of the mass m _{w b} and said kuiva35 the mass m of the substance _db quotient (m _w, b / m _d , b) is a value of the first. Generally, in the art, the proportion of moisture mass and dry matter mass

20155433 prh 08 -06-2015 is called the moisture content. The moisture content of the individual wood veneers 102 thus determined may be, for example, 60% to 200%. For the purposes of this specification, the moisture content of wood is referred to as the above-mentioned quantity.

In the pre-drying process, at least a portion of the wood veneer bundle 110 is disposed between a first planar surface 210 and a second planar surface 220. A planar surface is a surface that belongs to a plane; in other words, form part of the plane. Further, a planar surface is defined as a surface having a non-zero surface area po. plane; that is, po. surface muo10 gives a two-dimensional part of the plane. The opposite would be, for example, a roll whose surface forms only one level line or two lines. Alternatively, the surface may comprise portions such as the surface 220 of Figure 1. Preferably, each planar surface 210, 220 has a surface area of at least 0.5 m ² .

As shown in Figure 2, a planar surface (such as another surface 220) may consist of portions 221, 222, 223 with gaps 224, 225 therebetween, but such a surface still forms part of the plane. In addition, as shown in Figure 2, at the slots 224, 225, the wood veneer bundle does not remain on said surfaces 210,

220 in between. At slits 224, 225, a corresponding surface (such as a second surface

220) the compressive effect can be transmitted to the wood veneer bundle either through the bottom wood veneers or by using various supports, such as board 230 (Figure 1), for example plywood board 230.

The method transfers

- first surface 210 towards second surface 220,

a second surface 220 toward a first surface 210, or

- a first surface 210 toward a second surface 220 and a second surface 220 towards a first surface 210 to apply a surface pressure to the wood veneer bundle 110 to compress and pre-dry the wood veneer bundle 110.

It has been found that if the surface of the wood veneer bundle 110 is subjected at once to a sufficient surface pressure for pre-drying, several wood veneer 102 will easily break. As a result, the pressing is performed at varying surface pressures. Preferably, the surface pressure varies during compression so that the initial pressure is

20155433 prh 08 -06- 2015 high enough to straighten veneers and low enough to prevent cracking, and at a later stage the surface pressure is high enough to dry the veneers and low enough to keep the wood structure intact. The time-varying compression pressure can be seen in these two steps.

In a first step, a first pressure is applied to the wood veneer bundle 110 for a first period by means of said surfaces 210, 220. The first pressure is high enough to straighten and flatten the wood veneers 102, but low enough to prevent cracking. The first pressure may be between 1 bar and 13 bar. For example, the pressure may increase to the desired value and remain at this value, or the pressure may change with time. Pressure refers to the compression force per area, where the area refers to the cross-sectional area of the wood veneer bundle 110 having a surface normal to (or opposite to) the normal of the first pin 15 nan 210. Air pressure is not included in this clamping force, but pressure is the clamping force exerted by the surfaces 210, 220 on the bundle 110. The first time is sufficient to straighten and flatten the wood veneers 102. The first driving period can be long, although it can increase the production time and is therefore not necessarily economical. For example, the length of the first period of time may be at least 2 s. The first pressure may not be constant throughout the first period, but will be at least the length of said period within said pressure range.

After the first step, in the second step, a second pressure is applied to the wood veneer bundle 110 for a second period by means of said surfaces 210, 220. The second pressure is not necessarily constant throughout the second period, but is at least for the second time in the pressure range mentioned below. The second pressure is greater than 13 bar to provide sufficient pre-drying. The second pressure is less than 100 bar to maintain sufficient cellular structure of the wood for further use. The second time period is at least 150 s, preferably at least 300 s, to provide sufficient pre-drying. Under such pressure, a liquid comprising water and other substances is expelled from the wood veneer assembly 110.

The pre-dried wood veneer bundle 110 contains moisture of mass m _wa and dry matter of mass m _d , a. Because the liquid has been squeezed out, the pre-dried wood veneer bundle contains less moisture than the pre-dry20155433 prh 08 -06-2015 carpet wood bundle. Typically, the compressed puuviilunippu 110 includes moisture and a dry substance so that the humidity of the compressed puuviilunipun the mass m _{w, a,} and the compressed mass of dry matter puuviilunipun rrid.a quotient m _W, A / _d m, a is a second value which is at least 10 percentage points of the above first value m _W! b / m _d , b lower.

Water and other liquid may escape from the wood veneer bundle 110, for example, through surfaces between the veneers and through turning cracks and other gaps therein. In addition, the liquid may escape through the cells of the tree. For example, spruce (or wood grown in the spring) is the main pathway for the liquid. For example, in birch wood, tubular cells are the main pathway of fluid. In spruce, spring wood is softer than summer wood (that is, wood grown in summer), so it is slightly compressed when pressed. Correspondingly, spring tree extracts the liquid more easily than summer tree. For example, spruce typically has compressive pressures of less than 30 bar. Spring and summer trees are not as clearly distinguished as hardwoods. Liquid can also be squeezed out of hardwood. It may be that hardwood requires higher compression pressure than softwood.

In one embodiment, the first pressure is 2 to 10 bar and the length of the first period is 5 seconds to 3600 s. In one embodiment, the first pressure is 5 to 8 bar and the length of the first period is 5 seconds to 3600 s. length is 10s - 3600s.

In one embodiment, the second pressure increases as a function of time. It is clear that the second pressure may also decrease as a function of time. In particular, at the end of the compression, when the wood veneer bundle 110 is removed from the press, the press is opened, thereby reducing the pressure to zero. For example, the second pressure may increase so that the maximum compression pressure is reached at the earliest 150 seconds from the beginning of the second. In other words, the second pressure may increase, for example, so that the maximum compression pressure is reached not earlier than 150 s after the first compression pressure has exceeded 13 bar. It is also possible that the second period is not uniform. Thus, it is possible to apply a pressure of more than 13 bar to the veneer bundle during cold periods, so that the total length of the periods is at least the said second period.

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In one embodiment, the second pressure is

at least 15 bar for at least 120 s and thereafter

- at least 20 bar for at least 120 s.

In one embodiment of pre-drying a softwood, such as spruce, the second pressure is

between 19 and 23 bar for a period of 60 seconds to 300 seconds and thereafter

between 20 and 24 bar for a period of 60 seconds to 300 seconds and thereafter

between 21 and 25 bar for a period of 60 seconds to 300 seconds.

The corresponding pressure profile can also work for hardwood, such as aspen or poplar.

In one embodiment of pre-drying softwood, such as spruce,

the first pressure is 7 bar and the first time 12 s and

- the second pressure is • 20 bar for 140 s; thereafter • 21 bar for 140 s; and then • 22 bar for 140 s.

The corresponding pressure profile can also work for hardwood, such as aspen or poplar.

Depending on the need, several steps in the pressure profile can be used.

It has been found that as the pressure increases, the risk of bursting of the veneers 102 increases. For this reason, only pressures up to 30 bar are preferably used. More preferably, only pressures up to 25 bar are used. These limits apply specifically to conifers such as spruce.

Pre-drying can be facilitated using a spatially variable pressure profile. The spatial pressure profile is preferably slightly higher in the center region of the veneer bundle 110 than in the periphery of the veneer bundle. This makes it easier to squeeze the liquid out of the central area. The spatially variable pressure profile may be realized, for example, by arranging surface 210 into a surface of slightly flexible body 211 (Fig. 1) and by pushing body 211 towards surface 220 in the middle of body 211. If the body 211 is sufficiently rigid, for example, one hydraulic roller 212 of hyd20155433 prh 08 -06-2015 may be sufficient for such compression. Alternatively, for example, five hydraulic cylinders can be used, four of which are arranged as shown in Figure 2 and one exerts force on the central portion of block 211 (not shown). The spatial pressure profile can then be adjusted by adjusting the force exerted by the various cylinders. For example, the middle cylinder may produce more power than the others. This can be done at least at the beginning of the compression. As the compression progresses, the spatial profile can be adjusted as required.

This method is intended to reduce the energy required for actual drying. Thus, preferably, the pre-drying is preferably carried out at a temperature below 40 ° C, such as below 40 ° C, for example at room temperature. It is further advantageous for the pre-drying that the viscosity of the water is within a suitable range. For this reason, pre-drying is preferably carried out at a temperature of at least 10 ° C or at least 15 ° C.

The device 200 may become slightly warm during compression, although preferably the device 200 does not have heaters on the surfaces 210, 220. In one embodiment, the pressing surfaces 210, 220 have a temperature of less than 60 ° C or less than 50 ° C. The temperature of surfaces 210, 220 may be at least 10 ° C or at least 15 ° C.

Correspondingly, the temperature of the veneers 102 to be compressed is preferably not more than 55 ° C during compression to reduce energy consumption. Further, the temperature of the veneers 102 to be extruded is preferably at least 15 ° C during extrusion in order to obtain a suitable water viscosity.

The compression pressures used may depend to some extent on the type of wood used. This is due not only to the fact that the liquid is squeezed out of the coniferous tree at possibly lower pressures than the deciduous tree, but also because the coniferous tree may crack the deciduous tree more easily.

In softwood, such as spruce, the aforementioned second pressure is at least 13 bar, preferably at least 15 bar; at least for a while. Preferably, the second pressure in this range is at least 3 minutes, at least 4 minutes, or at least 6 minutes. Because the compressive strength of a softwood, such as spruce, is lower than that of a hardwood, a second pressure of a softwood, such as spruce, is preferably at most 60 bar, more preferably at most 50 bar, more preferably at most 30 bar.

20155433 prh 08 -06- 2015 bar and most preferably up to 25 bar. These values are particularly well suited for softwood material with an air dry density according to EN 384 of approximately 350 kg / m ³ to 550 kg / m ³ .

For hardwoods such as birch, the aforementioned second pressure is preferably at least 45 bar, more preferably at least 50 bar; at least for a while. Preferably, the second pressure in this range is at least 3 minutes, at least 4 minutes, or at least 6 minutes. Since hardwood, such as birch, has a higher compression strength than softwood, hardwood, such as birch, has a second pressure of up to 100 bar, preferably up to 90 bar, all the time. These values are particularly well suited for hardwood material with an air dry density according to EN 384 of about 520 kg / m ³ to 670 kg / m ³ .

Pre-drying has been found to dry the veneers 102 of the veneer bundle 110. Some examples are shown later in Table 2. The amount of liquid exited from the veneers 102 depends, e.g. about the veneers to be pressed by themselves (wood species, wood quality (heartwood / hardwood), moisture), the number of veneers, the surface pressure used for pressing and the pressing time. Referring to Table 2, the moisture content of the veneers decreased by at least 25 percentage points and at most 60 percentage points during pre-drying in some experiments. Typically, pre-drying is economically viable if the compression pressure and time are so selected, during pre-drying, the moisture content of the veneer bundle 110 is reduced by at least 10 percentage points, more preferably by at least 20 percentage points or at least 25 percentage points.

Referring to Figure 4, the amount of water exited at a surface pressure was particularly affected by the compression time. However, drying at too low a surface pressure does not result in measurable amounts due to compression.

Referring to Tables 2 and 4, after pre-drying, for example, the moisture content of pre-dried coniferous veneers, such as spruce veneers, may be between 40% and 130%. More typically, if only the moistest wood is dried, the moisture content of the pre-dried spruce veneers can be between 80% and 130% or 90% to 125%. If a large number of veneers with a moisture content of less than 90% prior to pre-drying are selected for moisture content, the moisture content may be lower than the above values.

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After pre-drying, for example, the moisture content of pre-dried hardwood veneers, such as birch veneers, can be between 20% and 65%. More typically, if only the humid wood is dried, the moisture content of the pre-dried birch veneers can be between 30% and 65% or 30% to 55%.

A device for carrying out the method of pre-drying is described below. One such device comprises a control unit arranged to control the surface pressure during pre-drying. It will be appreciated that the control unit may be arranged to adjust the surface pressure according to any of the pressure profiles described above.

Preferably, the wood veneers 102 are arranged in a bundle 110 such that the fiber directions of at least some of the two adjacent wood veneers 102 are substantially parallel. Preferably, the fiber directions of all wood veneers are substantially parallel. The directions of the fibers are substantially parallel when the directions determined by the fibers of the veneers (i.e. the directions determined by the causes of the wood, i.e. the autumn directions) differ by no more than 20 degrees. Such placement of veneers 102 also has an effect on cracks of veneers 102 in compression.

It has been found that such pre-drying not only dry the veneers 102, but also smoothes the moisture of the veneers 102. In other words, wetter veneers 102 exert more moisture than dry veneers. Possibly very dry veneers get slightly wet. This has the advantage that further drying does not have to be oversized because the material to be dried has a relatively homogeneous moisture content.

In one embodiment

- the relative standard deviation of moisture content of the wood veneers 102 of said wood veneers 110 prior to pre-drying is a third value,

- the relative standard deviation of the moisture content of the wood veneers 102 of said wood veneer 110 after pre-drying is a fourth value, and

- the fourth value is at least 2 percentage points lower than the third value.

Relative standard deviation means the ratio of the standard deviation to the mean power, in units of one percent. In many cases, a reduction of at least 5 percentage points in relative summer can be achieved by pre-drying

20155433 prh 08 -06- 2015 in dispersion. As Table 2 shows, a reduction of up to 10 percentage points in relative standard deviation is often achievable. In addition, according to Table 2, a reduction of at least 3 percentage points in absolute standard deviation can be achieved by pre-drying.

In addition, pre-drying by compression smooths the thickness of the veneers. In other words, typically, the thickness variation of a single veneer in the given veneer. the veneer area after pre-drying is smaller than before pre-drying. However, the variation in the average thickness of the veneers between the various veneers may increase. Drying the pre-10 may reduce the thickness of the veneer, for example by 5% to 10%, which should be considered if the final veneer thickness is significant for use. The thickness of the veneer at the end may be, for example, 0.5 mm to 5 mm, and the thickness of the unpressed veneer, for example, may be 0.5 mm to 6 mm.

Figure 6 illustrates the entire process for making dry wood veneers. The foregoing compression pre-drying is described in the section entitled '' Pre-drying '. The wood veneers 102 may have been manufactured by turning, and the veneer mat 103 obtained from the turning may be sawn or cut to form the wood veneers 102.

It has further been found that the above pre-drying method is particularly well suited to pre-drying long-headed veneers. Referring to Figures 3a-3c, a long-headed wood veneer is a turned wood veneer that is turned so that the length of the edges of the veneer is greater than the length of the center line of the veneer. Depending on the type of turning, there may be more material in the periphery than in the center; or the material may be less in the periphery than in the center if the material is thinner in the periphery than in the center. Fig. 3a illustrates a log 150 of a long-headed veneer mat 103. As the edges of the long-headed veneer mat are longer than the center line, the edges slightly curl as shown. 3c, the wood veneer 103 thus produced is further cut or sawn into wood veneer 102a, 102b, 102c to the desired length. In Fig. 3c, the cut-off lines are illustrated with dashed lines.

Figure 3b shows the remainder of the logs after turning 150 long-headed wood veneers, i.e. the chisel, which, as shown, is slightly centered

20155433 prh 08 -06- 2015 thicker than the edges. As shown in Figures 3a and 3b, the long-headed veneer mat 103 is turned so that the lathe blade is in the periphery of the log 150 closer to the axis of rotation of the log 150 than in the central area of the log. Preferably, at least most of the wood veneers 102 are long-headed.

It has been found that with long-headed wood veneers, cracking is significantly less frequent than with flat or short-headed wood veneers. It is likely that the peripheral areas of the long-headed wood veneer 102 will straighten in the pre-compression without breaking, and this straightening will, in particular, stretch the middle region of the veneer 102 without breaking it. In addition, in the case of a long-headed veneer, a length greater than the center region of the peripheral area causes the peripheral regions to undergo compression parallel to the plane of the veneer sheet. Such compression prevents the veneer sheet from cracking.

Figure 3c further illustrates the fiber direction of the veneers 102 and the fluid exit from the veneer during compression. The liquid is discharged especially in the fiber direction.

Examples of wood suitable for turning and pre-drying are spruce, birch, pine, poplar, beech and aspen. Correspondingly, veneer 102 may consist of wood material of any of said wood species. Preferably, the veneers are made of spruce or birch.

Softwood veneers typically have a thickness of 1.0 mm after drying

4.0 mm, such as 1.4 mm - 3.6 mm; and, for example, about% to 10% thicker before pre-drying. Typical thicknesses for dry spruce veneer are e.g. 1.5 mm; 2.0 mm; 2.6 mm; 3.2 mm and 3.6 mm.

Hardwood veneers, after drying, are typically 0.8 mm in thickness to 3.0 mm, such as 1.0 mm to 2.0 mm; and most preferably 1.2 mm to 1.6 mm. Birch veneer thickness is typically 1.5 mm. For example, typical thicknesses for aspen and poplar are 2.6 mm and 3.0 mm. For example, the thickness before the pre-dry is about 3% -10% higher.

Referring to Figure 6, logs 150 are typically incubated before turning. There are different methods of incubation. The Finnish plywood mills are in general use13

20155433 prh 08 -06- 2015 is a method of incubation in logs in warm water. Other incubation methods include incubation as peeled bolls in warm water and incubation as bolls in water vapor or sprinkled in a mixture of water vapor and water. The latter type of incubation is suitable for hard-to-burial wood species such as oak and beech. The purpose of the incubation is to return the fresh moisture to the log, which facilitates turning.

If the incubation method involves soaking logs in solution, the logs are incubated for at least 12 hours, typically about 24 hours, in solution. The solution is mainly water. For example, the temperature of the solution is at least 20 ° C, more preferably at least 30 ° C, and most preferably at least 35 ° C. Raising the temperature reduces the required incubation time but increases energy consumption. Preferably, the temperature of the solution is below 95 ° C. In one embodiment, the pre-drying liquid from the veneers is led to a solution used in the incubator (see Figure 6). In this way, the liquid pressed out of the veneers is utilized. Hatching logs are typically sawn from the trunks.

Incubation also has the advantage that soaking heats the wood to the right temperature. This facilitates turning. This also facilitates the pre-drying process if the veneers move relatively quickly through the lathe and by sawing or cutting to the pre-drying process. Temperatures slightly above room temperature can facilitate pre-drying by compression, since the viscosity of the water is temperature dependent. On the other hand, too high a soaking temperature can soften the wood in view of pre-drying by pressing. More preferably, the temperature of the solution is below 50 ° C. The temperature of the solution may be, for example, 35 ° C to 45 ° C. The use of chemicals, such as acids or bases, can also soften the wood for over-pressing. Preferably, the pH of the solution is between 4 and 10, such as 5-9 or 6-8.

As discussed above, one of the benefits of pre-drying is that the moisture dissipation of the wood veneers going to actual drying is less than without pre-drying. It has been found that the moisture content of conifers in particular depends on where the moisture is examined. After incubation, typically coniferous trees have a lower moisture content than heartwood. For example, the moisture content of spruce heartwood is between 30% and 60%, while the moisture content of the topwood is

20155433 prh 08 -06-2015 is typically between 60% and 200% (see definition of moisture content above). Similarly, fresh spruce density, as well as spruce density after hatching, is typically in the range of 700 kg / m ³ ± 250 kg / m ³

In deciduous trees the corresponding dispersion is smaller. For example, the birch moisture content after hatching may be 25% to 75%, preferably 35% to 55%. Similarly, fresh birch density, as well as birch density after incubation, is typically in the range of 830 kg / m ³ ± 100 kg / m ³ .

Due to the objective of reducing moisture variation, preferably turned wood veneers 102 are divided (i.e. classified) into two classes according to their moisture content, and only wetter wood veneers are pre-dried by compression. This is shown in Figure 6 under '' sorting by moisture content ''. Wood veneer can be classified, for example, in the humid category when the moisture content 15 exceeds a threshold of 40% to 80%. If the moisture content is below or equal to this limit, the veneer is classified in the drier category. For hardwoods, such as birch, the limit may be, for example, 40% to 50%. For conifers, such as spruce, the limit may be, for example, 70% to 80%.

Since softwood is known to have a lower moisture content than heartwood, it is possible to classify softwood according to whether the veneer is 102 or hardwood. At least the surface veneers are preferably pre-dried by compression. In addition, it is advantageous to pre-dry only the surface 25 by squeezing wood veneers. In this case, the above classification can be made on the basis of the quality of the wood without measuring moisture.

After pre-drying, the pressed wood veneers are dried. This is shown in Figure 6 under '' drying ''. Typically, the veneers are individually dried because the individual veneers dry faster than the veneers. In one embodiment, the pre-dried veneer sheets are dried so that:

disassembling the wood veneer assembly 110 to form individual pressed wood veneer 102s, and

drying the individual wood veneers with a drying gas at a temperature of at least 150 ° C for at least 90 s.

One significant benefit of pre-drying is that the time required for actual drying is reduced. Likewise, the amount of energy required for drying is reduced.

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Any gas or steam heated process known per se is used to dry the veneers. An important factor in drying is to raise the temperature of the cotton to be dried to a temperature in the range of 100 ° C to 120 ° C, where the veneer dries as the water boils, but on the other hand the veneer material does not change significantly.

The temperature of the drying gas is preferably below 210 ° C because at higher temperatures the risk of ignition of the veneers increases if the drying gas contains oxygen. In addition, at higher temperatures, the veneers easily darken, which is not always allowed for use. The temperature of the drying gas may be, for example

150 ° C to 190 ° C, such as about 160 ° C to 180 ° C. In order to accelerate drying, the drying gas can be flowed, for example, by means of various fans and / or the wood veneers are transported in the drying gas. For example, the drying gas flow rate relative to the wood veneers (when either or both are moving) can be at least 15 m / s. The drying time depends on several factors, such as

- the desired moisture content,

- wood veneer material,

- the moisture content of the veneers to be dried before drying,

- the temperature of the drying gas,

the relative humidity of the drying gas, and

- the flow rate of the drying gas in relation to the wood veneers.

Roll dryers are known in the art where rolls are used to transfer veneers to the dryer. In addition, mesh dryers are known in the art where veneers are transferred between the meshes to the dryer.

According to Figure 6, in one embodiment, both wood veneers that have been pre-dried by compression and wood veneers that have not been pre-dried by compression are dried. Advantageously, in this embodiment, only wood that has been found to be wetter (i.e. classified) is pre-dried, whereas wood that has been found to be drier (i.e. classified) is not pre-dried. The classification of wood veneers before pre-drying is given above.

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After drying, the moisture content of the wood veneers is preferably less than 7%. This is preferably the case for at least most wood veneers when the moisture content is defined as the average moisture content of the individual wood veneers.

The moisture content of individual wood veneers may vary locally. Preferably, a large portion of the wood veneers is dried sufficiently dry already in one drying run. Preferably, after drying, at least 75%, such as at least 90% or at least 95%, of the wood veneers are those having an average moisture content of less than 7%. In this case, one drying time is sufficient for most wood veneers.

It is often advantageous for further use that the veneer is not completely dry. For example, a degree of residual moisture in the veneers contributes to the veneer bonding. For example, the desired moisture content after drying may be 3%. While there is some disintegration in the moisture content of the veneers before drying, it is preferable that not all wood veneers be dried to the target level or drier at once. For example, in one embodiment, after the first drying, at least 5% of the wood veneers are those having a moisture content of at least 3%.

Wood veneer (s) which, after drying, have too high a moisture content, may be re-dried using the drying gas after the first drying as described above. This is illustrated in Figure 6 ('' Drought Check '').

In one embodiment, the re-drying is done so that:

- after drying, measure the moisture content of the individual wood veneer 102,

- detection of a moisture content exceeding the limit value, and

- drying said wood veneer again with a drying gas.

Said limit may be, for example, 10%, 7% or 5%.

Dry wood veneers thus produced can be used, for example, to produce a laminated wood product. The layered wood product may be, for example, parquet or plywood.

Device

20155433 prh 08 -06- 2015

Figures 1 and 2 show a device 200 suitable for pre-drying a bunch of wood veneer 110 by compression. The device 200 comprises a planar first surface 210 which forms a two-dimensional part of the plane. Surface 210 may be the surface of body 211. The device further comprises a planar second surface 220 which forms a two-dimensional portion of the plane. The second surface 220 is parallel to the first surface 210; that is, the normal of these surfaces are in the same (or opposite) direction. The first surface 210 and the second surface 220 are at least partially overlapping, leaving a space 202 for the pre-drying wood veneer stack 110 between the first surface and the second surface. at least one two-dimensional portion of the normal projection of the second surface 220 to said plane. Each of the surfaces 210, 220 or both may be integral, i. For example, in Figures 1 and 2, the first surface 210 is integral, and the second surface 220 comprises portions 221, 222 and 223.

As the surfaces 210, 220 are thus positioned relative to one another, there is a space 202 therebetween for the material to be compressed, such as a pre-drying wood veneer stack 110 (see Figures 1 and 2). Said surfaces 210, 220 define space 202 in two directions. In one embodiment, surfaces 210, 220 have no protrusions, at least during compression, whereby only said surfaces 210, 220 define space

202 from said two directions. For example, in Figures 1 and 2, only planar surfaces 210, 220 define space 202 during top and bottom extrusion. The surfaces 210, 220 may be formed, for example, of a metal plate surface. A corresponding slab, in particular a stationary slab, may be provided on the surface of the concrete slab. As described below, when the device 200 is not used for compression, a portion of the conveying means (424, 425) may rise, for example, from the second surface 220 toward the first surface 210, whereby po. the transport means (424, 425) may define a po. space 202 when device 200 is not used for compression.

The device 200 further comprises means 212 for moving the first surface 210 toward the second surface 220 and / or for moving the second surface 220 toward the first surface 220.

20155433 prh 08 -06-2015 surface 210 to apply a surface pressure to a material (such as wood veneer 110) in said space 202 and to compress such material. Figures 1 and 2 show a hydraulic cylinder 212 for moving the first surface 210 toward the second surface 220.

The device 200 further comprises means for adjusting the surface pressure. By moving the surfaces 210, 220 towards one another, the material arranged in the space 202 can be compressed, whereupon the material is subjected to surface pressure. The surface pressure can be varied (or adjusted), for example, by changing the distance between the surfaces 210, 220 (or by adjusting). Thus, the hydraulic cylinder 212, its propulsion force, and the propulsion control provide means for adjusting the surface pressure. The propulsion control is arranged in the control unit 310 in Figure 1.

Pre-drying is preferably carried out using surface pressure, which changes over time from the first region to the second region and possibly other regions. Therefore, the device 200

means 212 for moving the first surface 210 toward the second surface 220 and / or for moving the second surface 220 toward the first surface 210 to apply surface pressure to the material 20 in said space 202

- means for adjusting said surface pressure are arranged to adjust said surface pressure to at least a first value and a second value. Said first value is at least 1 bar and at most 13 bar. The second value mentioned is more than 13 bar. Said second value is preferably not more than 100 bar.

The device 200 further comprises means 212 for displacing the first surface 210 away from the second surface 220 and / or moving the second surface 220 away from the first surface 210 to form said space 202 thereafter. Once the surfaces 210, 220 have been moved far enough apart, the pressed wood veneer assembly 110 may be removed from the device 200. In addition, an uncompressed new wood veneer assembly 110 may then be moved into the space 202 of the device 200 for compression.

20155433 prh 08 -06- 2015

Compression does not require heating. In one embodiment, the device 200 does not comprise a heater arranged to heat the first surface 210 or the second surface 220.

In one embodiment, the control unit is provided

- control the surface pressure by means of means 212 such that the surface pressure is between 1 bar and 13 bar for at least two seconds,

means 212 for increasing the surface pressure to a level greater than 13 bar; and

- controlling the surface pressure by means of means 212 such that the surface pressure is between 13 bar and 100 bar for at least 150 seconds.

In one embodiment, the means 212 for moving the first surface 210 toward the second surface 220 and / or for moving the second surface 220 toward the first surface 210 to apply surface pressure to the material 110 in said space 202 are arranged to move the surfaces 210, 220 at least 800mm, preferably at least 1100mm , such as at least 1300 mm. This provides the advantage that the device 200 is suitable for pressing a plurality of thicknesses of wood veneer 110 in various thicknesses. In one embodiment, the first surface 210 and the second surface 220 are movable to move the first surface 210 of the devices 212 away from the second surface 220 and / or to move the second surface 220 away from the first surface 210 at least 1000 mm, preferably at least 1500 mm apart. Such a device is suitable for pressing a relatively high bundle of wood veneer, whereby the initial cost savings compared to the pressing of individual veneers are significant.

Preferably, the device 200 is suitable for pressing relatively large areas of wood veneer. In one embodiment, said first surface 210 comprises one or more portions and said first surface portion or the combined surface area of said first surface portions is at least 1 m ² . For example, in Figures 1 and 2, the first surface 210 is integral, i.e. comprises only one portion. In one embodiment, said second surface 220 comprises one or more portions, and the surface area of said second surface portion or the combined surface area of said second surface portions is at least

1 m ² . For example, in Figures 1 and 2, the second surface 220 comprises portions 221, 222 and

223 with a total area of at least 1m ² . Preferably both

20155433 prh 08 -06- 2015 surface 210, 220 separately; or a surface area of at least 2 m ^2, and more preferably at least 3 m ^2, of the surface of each surface portion. For example, in Figures 1 and 2, surface 210 may have a surface area greater than 2 m ² and total surface portions 221, 222, 223 may have a surface area greater than 2 m ² .

The device of Figure 2 comprises four hydraulic cylinders 212. By using a plurality of hydraulic cylinders 212, the surface pressure can be adjusted to be quite uniform and sufficiently high even over a large area. Preferably, the device comprises four, at least four, five, at least five, six, or at least six hyd10 roll rollers 212 for moving surfaces 210, 220 towards each other. Six may be a suitable number, for example if the surfaces 210, 220 are shaped such that their length is greater than their width.

Preferably, of the surfaces 210, 220 only the first 210 is arranged to be movable with respect to the ground while the second 220 is stationary with respect to the ground (or floor) during compression. This has the advantage that less actuators are needed to move only one surface than to move two surfaces. Preferably, surfaces 210, 220 are horizontal. This provides the advantage that the material 110 can be moved into the space 202, and the material 110 is naturally supported by its gravity on its substrate, for example the second surface 220. Further preferably, the first surface 210, i.e. the movable surface 210, is arranged above the second surface 220. This can facilitate the transport of material to and from the space 202 of the device. In addition, a conveyor 424, 425 for transferring material such as wood veneer 110 is typically arranged at the floor level.

In this case, if only the upper surface 210 is arranged to be displaceable, the upper surface 210 may, after compression, be raised to a height sufficiently high for the next veneer bundle 110. In other words, there is no need to raise the surface higher than this. This will speed up the process. If the lower surface 220 were movable, due to the conveyors, it would have to be lowered to the floor level after pressing and lifted up for pressing during pressing, which would slow down work. This is especially true if the device 200 is available for pressing multiple thicknesses of material; wherein surfaces 210, 220 can be moved further apart than a typical material thickness. Further, the fluid flowing from the material 110 during compression cannot, in such an embodiment, flow to the hydraulic cylinders 212.

20155433 prh 08 -06- 2015

Preferably, the device 200 comprises means 424, 425 adapted to move the wood veneer assembly 110 into said space 202. Such means may comprise, for example, a lifting device with a boom.

Figures 1 and 2 show a preferred embodiment of such means 424, 425. In the device 200 shown in Figures 1 and 2, the second surface 220 comprises three portions 221, 222, 223, between which portions 224, 225 remain. The slots 224, 225 extend parallel to each other. The device 200 comprises means 424, 425 for moving the wood veneer assembly 110 into the space 202. The means 424, 425 comprise rolls or rolls and, optionally, straps thereon. At least a portion of the means 424, 425 for moving the bundle of wood veneer into said space 202 are provided in the slots 224, 225 shown in the figures.

Further, in the device 200 shown in the figures, the means 424, 425 are arranged by means of it or the like so that when the device 200 is not used for compression, at least a part of the means 424, 425 is raised by a spring or the like above the second surface 220. The spring or the like is so dimensioned that the means 424, 425 are raised in this manner even when a wood veneer bundle 110 is on top of them. means 424, 425 delimit space 202, and second, po. means 424, 425 may be used to move the wood veneer assembly 110. Optionally, the transfer 230 may be supported by a sheet 230, such as plywood sheet 230. Similarly, when the device 200 is used for pressing, the pressing force pushes the means 424, 425 into slots 224, 225, whereby only planar surfaces (first surface 210 and second surface 220)

Preferably, the device 200 comprises means adapted to move the pre-dried bundle of veneer 110 out of said space 202. The same means or the same means 424, 425 may serve as means for moving the wood veneer assembly 110 into the space

202 and out of space 202.

The device 200 according to one embodiment comprises a control unit 310 (see Fig. 1) arranged to control the pressure exerted on the material 110 by means of the means 212.

20155433 prh 08 -06- 2015

The device 200 according to one embodiment has a display unit 320. The display unit 320 is arranged to display at least

surface pressure exerted by the device 200 on material 110 in state 202, and / or

- desired surface pressure.

The desired surface pressure is the setpoint pressure that the device tends to apply to the material 110. Adjustment of the surface pressure to the setpoint is obvious to one skilled in the art.

The device further comprises at least one button 332 which enables the user to

- adjusting the surface pressure exerted by the device 200 on the material 110 in its state 202 and / or

- program the desired surface pressure on the device.

Further, the display device 320 may be arranged to display a pre-programmed time for the device to maintain the desired surface pressure. Alternatively, the display device 320 may be arranged to display the time during which the surface pressure has been applied to the material 110 in the state 202 of the device 200. After a suitable time, the user may adjust the surface pressure to a desired new level (e.g., 332), or the device 200 may be configured programmed pressure profile. The device may comprise said button 332, for example in the keypad 330, which may be utilized, for example, in programming the pressure profile.

It has been found that the above pre-drying device 200 is particularly well suited for pre-drying long-headed veneers. This is because it has been found that it is the long-headed wood veneer that has been found to withstand pre-drying by compression without cracking better than otherwise turned wood veneer. Referring to Figures 3a-3c, a long-headed wood veneer is a turned wood veneer that is turned so that the length of the edges of the veneer is greater than the length of the center line of the veneer. Depending on the type of turning, there may be more material in the periphery than in the center; or the material may be less in the periphery than the center if the material is thinner in the periphery than in the center. Figure 3a illustrates the support 150 of the long-headed wood veneer mat 103. Since the edges of the long-headed veneer mat are longer than the center line, the edges are slightly undulating as shown in the figure23.

20155433 prh 08 -06- 2015 sesti. 3c, the wood veneer 103 thus produced is further cut or sawn into wood veneer 102a, 102b, 102c to the desired length. In Fig. 3c, the cut-off lines are illustrated with dashed lines.

Fig. 3b shows the remainder of the logs 150 after turning the long-veneered wood veneer, i.e. the chisel, which, as shown, is slightly thicker in the middle than at the edges. As shown in Figures 3a and 3b, the long-headed veneer mat 103 is turned so that the lathe blade is in the periphery of the log 150 closer to the axis of rotation of the log 150 than in the central area of the log. Preferably, at least a large portion of the wood veneers 102 are long-headed. A length greater than the center region of the periphery of the long veneer causes compression to occur in the peripheral areas parallel to the plane of the veneer sheet 102 during compression, which prevents the veneer sheet 102 from cracking.

Referring to Figures 3a-3c, the device 200 may be part of an arrangement further comprising a lathe. Such a lathe, in particular its blade, is preferably arranged so that the po. when using lathe, the long-headed wood veneer will be turned. Such an arrangement has the advantage that cracks in the veneers can be reduced.

results

In one example, a spruce carpet was turned into a bundle that was cut into 60 bundles of 1300 mm χ

1300 mm wooden veneers. One of these stacks was further sawn into four bundles of wood veneers, which consisted of wood veneers between 600 mm and 600 mm in size. The thickness of each wood veneer before pre-drying was within the manufacturing accuracy of 2.0 mm.

The smaller bundles of wood veneer were pre-dried by compression using different compression pressures and times. The bundles of wood veneer were weighed before and after pressing. After pre-drying, the wood veneers were dried in the oven with drying gas as described above. The mass and thickness of the veneers were measured before and after the actual drying. The moisture content of the wood veneers prior to pre-drying ranged from 69% to 155% with an average of 109%. Initially, the thickness of the wood veneers is such that without pre-drying, after oven drying alone, the dry wood veneer has an average thickness of 2.01 mm. According to the tests, a pressure of at least 13 bar, preferably at least 15 bar, is required for the liquid to be pressed from the wood veneers. Table 1 shows some experimental results. The amount of water lost is expressed in volume. Volume refers to the calculated volume, ie the product of the nominal thickness and the total area. The total area, in turn, is the area of a single sheet of veneer 102 or the total area of the veneer 102 of the entire veneer bundle 110.

Compression- pressure (MPa) Compression- time (Min) Quantity of water discharged (kg / m ³ ) moisture content after compression (%) Thickness of veneer after pressing and drying (Mm) 1.5 30 29 108 1.99 3.0 30 193 64 1.91 3.0 15 175 75 1.92

Table 1. Effect of compression on moisture content and veneer thickness.

20155433 prh 08 -06- 2015

Larger bundles of 60 plywood 1300mm x 1300mm wood veneer were also pre-dried by compression and then dried. These were dried at a pressure of 2.6 MPa (or 26 bar) for 16 minutes. In these tests, 132 kg / m ³ of fluid was squeezed out. In addition, it was found that the moisture dispersion after compression was greatest in the middle region of the wood veneer bundle. According to the tests, it seems that pressing especially dries the edges of the bunch of wood. In the tests, the liquid leaked in particular from the ends of the veneers which were substantially perpendicular to the fiber direction of the veneers. This is understandable since the liquid is squeezed out of the veneers along the tissue and / or cracks in the wood. In addition, it was found that the compression time required for pressing with larger area veneers is greater than with smaller wood veneers. In addition, compression smoothed the variation in the thickness of the wood veneers.

Prior to compression, the weight of the wood veneers was between 2270 g and 3530 g, the mean being 3065 g and the standard deviation 355 g. After squeezing, the wood veneer mass ranged from 2300 g to 2860 g with an average of 2620 g and a standard deviation of 125 g.

20155433 prh 08 -06- 2015

In another example, 2600 mm χ 1000 mm χ 2 mm wood veneers from lathe sawdusts were selected and selected with a moisture content of at least 70%. The wood vectors thus selected were formed into bundles of wood veneers, each comprising 50 veneers. The wood veneer bundles were dried by pressing for a period of 30 minutes. The final compression pressure was 3 MPa. The compression pressure was increased to the final compression pressure during the first minute. In this case, the compression pressure was between 1 bar and 15 bar for about half a minute. The individual veneers were weighed before and after pressing. The amount of fluid removed by compression was measured as a function of time. Figure 4 shows the amount of water discharged as a function of time. It can be seen from the figure that the drying rate slows down during pressing. In addition, the picture shows that the drying is quite rapid during the first 4-9 minutes.

For Tables 2 and 3, a plurality of the wood veneer bundles described above in connection with Figure 1 were formed and the wood veneer bundles pre-dried by compression for a period of 5, 10, 15 or 20 minutes. At 10, 15 and 20 min, Tables 2 and 3 show the results of two different measurements. A total of seven different bundles were measured for moisture removal during pre-drying. One bundle was compressed for 5 min, two for 10 min, two for 15 min and two for 20 min.

Table 2 shows the amount of water removed and the moisture content before and after pre-drying. The moisture content of the individual wood veneers comprising a bunch of wood veneer pressed or pressed, when the moisture content itself is defined as the quotient of the moisture mass and the dry matter mass. X represents the average moisture content of the wood veneers and s represents the standard deviation of the moisture content. The amount of water discharged is determined by weighing the veneers before and after pressing, and the volume of water discharged is proportional to the volume of vii30 lu. The x in Table 2 represents the average amount of water discharged from the veneers and s represents the standard deviation of the amount of water exited from the veneers.

Bunch the press Moisture content before Moisture content The amount of water discharged No. horizon in the (Min) compression (%) Xs after staging (%) Xs (kg / m ³ ) xs 1 5 153.3 61.9 121.3 27.1 102.7 85.6 2 10 161.9 33.8 128.6 14.2 84.9 81.7 3 10 135.6 47.4 109.0 17.8 56.8 74.2 4 15 152.2 57.0 113.8 25.2 153.7 79.2 5 15 155.0 38.4 117.4 16.0 120.0 71.5 6 20 161.0 59.3 102.2 20.9 196.4 66.0 7 20 144.8 29.9 102.8 11.1 160.5 81.3

Table 2. Changes in moisture content and its dispersion during pre-drying.

Table 3 shows the thickness change during pre-drying and drying. Thickness refers to the average thickness of individual wood veneers before, after, before, or after pressing and drying. For reference, the thickness of the wood veneers which were merely dried is shown. As stated above, only a portion of the wood veneers (i.e., the wettest wood veneers) were pre-dried by compression. It can be seen from Table 3 that pre-drying by pressing also thins wood veneers. The thinner the stronger the longer the compression continues. It may also be that the thinner the pressure is, the greater the pressure. In addition, wood species may have an impact on results.

20155433 prh 08 -06- 2015

Bunch No. Compression- time (Min) Thickness of wood veneer (mm) after compression and drying wood veneer thickness benchmark (Mm) Before compression after compression 1 5 2.22 2.11 2.05 2.16 2 10 2.21 2.09 2.03 2.11 3 10 2.14 2.10 1.90 1.93 4 15 2.18 2.03 2.03 2.13 5 15 2.17 2.09 1.90 1.96 6 20 2.21 2.09 2.07 2.15 7 20 2.20 2.12 1.91 2.01

Table 3. Changes in wood veneer thickness during the pre-drying and drying process.

In a third example, spruce veneers coming from lathe sawdusts were 2600 mm mm 1000 mm χ 2 mm in size and pre-dried in wood veneers at 3.0 MPa for 10 minutes or 40 minutes. Table 4 shows the results in which the wood veneer bundles 1 and 2 consisted only of surface wood, while bundle 3 comprised both surface wood and heartwood. Each veneer was weighed before and after pressing. In addition, the moisture content was measured from the three veneers of each bundle at the center and edge areas.

As shown in Table 4, 161 kg / m ³ water was extruded from the veneers in 40 minutes. Half of that amount was squeezed out in the first ten minutes. Thus, the water removal rate decreases after about ten minutes of compression. Stack 3 also included heartwood, and from Table 4 it is observed that the amount of water removed by squeezing is considerably less. Water cannot be squeezed out in significant quantities from the heartwood. Table 4 shows that the standard deviation of the moisture content, including the relative standard deviation calculated from different wood veneers, is reduced by compression. In addition, the dispersion of moisture content of each veneer, calculated from the moisture content at different points of one veneer, is reduced by compression. Liquid can also be squeezed out of the center of the veneers, but this is slower than pre-drying the edge areas by squeezing. In Table 4, x denotes the mean moisture content and s the absolute deviation of the moisture content.

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Bunch nr. Veneer quality plies number- amount Pressure (MPa) Time (Min) Humidity before (%) Moisture- content after (%) Amount of liquid removed (kg / m ³ ) X s X s 1 Sapwood 26 3.0 40 128 16 88 8 161 2 Surface Wood and Sy- 24 3.0 10 133 26 114 13 78 3 dänpuu 56 3.0 10 47 37 41 26 23

Table 4. Changes in moisture content of veneers during pre-drying in some experiments.

Figure 5 further shows the results for the site. Edges A and B refer to the edges of the veneer, which are adjacent to edges perpendicular to the direction of the veneer causes. Referring to Figure 3c, the liquid is expelled especially from these edges. On the other hand, fluid is squeezed out of the central region

20155433 prh 08 -06- 2015 especially through these edges. From Figure 5, it can be seen that the moisture is most evenly distributed in the middle region.

examples

A method for pre-drying a bunch of wood veneer by a method

- providing a plurality of turned lathe-like wood veneers containing a total moisture and dry matter content of at least 45% by weight of said moisture mass and said dry matter,

- assembling at least twenty of said lamellar wood veneers into a stack of wood veneers, wherein the wood veneer bundle contains moisture and dry matter such that the ratio of said moisture mass to said dry matter mass is a first value,

- providing at least a portion of said wood veneer bundle between a first and a second surface, the first surface forming a two-dimensional part of the plane and the second surface forming a two-dimensional part of the plane,

- moving the first surface toward the second surface and / or the second surface toward the first surface to apply surface pressure to the wood veneer bundle to compress and pre-dry the wood veneer bundle,

- applying said surfaces to the wood veneer bundle to a surface pressure of • at least 1 bar and at most 13 bar for at least 2 seconds, and thereafter • at greater than 13 bar for at least 150 seconds during one or more time periods and at most 100 bar,

squeezing liquid out of the wood veneers, and

- compressing the pre-dried bundle of wood veneer so that the compressed bundle of wood contains moisture and dry matter such that the moisture content of the bundle of wood and the dry weight of the bundle of wood bundle have a second value which is at least 10 percentage points lower than said first value.

The method of Example 1, wherein

- applying said surfaces to the wood veneer bundle with a constant or variable first pressure for a first time, which first pressure

20155433 prh 08 -06- 2015 is at least 1 bar and at most 13 bar and every first time is at least 2 s and after

- applying said surfaces to the wood veneer bundle to apply a second pressure constant or variable over time, said second pressure being greater than 13 bar and not more than 100 bar, and the second time being at least 150 s.

A process according to Example 1 or 2 wherein

- the relative standard deviation of the moisture content of the wood veneers of said bunch of wood prior to pre-drying is a third value,

- the relative standard deviation of the moisture content of the veneers in said bundle of wood after pre-drying has a fourth value,

- the fourth value is at least 2 percentage points lower than the third value.

A process according to any one of Examples 1 to 3, wherein

- said surface pressure increases with time • when said surface pressure is up to 13 bar or • when said surface pressure is greater than 13 bar or • when said surface pressure is up to 13 bar and when said surface pressure is greater than 13 bar.

A process according to any one of Examples 1-4 wherein (A)

- said surface pressure is always up to 30 bar; preferably not more than 25 bar or (B)

- said surface pressure is greater than 45 bar for at least 120 s.

The method according to any one of Examples 1 to 5, wherein the surface pressure has a spatial profile such that the surface pressure in the middle region of the wood veneer bundle is greater than in the peripheral region of the wood veneer bundle.

A process according to any one of Examples 1-6, wherein

- a surface pressure of at least 15 bar for at least 120 s and thereafter

- a surface pressure of at least 20 bar for at least 120 s.

The method of any one of Examples 1-7, wherein

20155433 prh 08 -06- 2015

- a surface pressure of from 5 bar to 8 bar for at least 5 seconds, preferably up to 3600 seconds;

advantageously

- the surface pressure is 5 bar to 8 bar for at least 5 seconds before the surface pressure 5 first exceeds 13 bar.

The process of any one of Examples 1-8, wherein

the surface pressure is between 19 bar and 23 bar for a period of 60 seconds to 300 seconds and thereafter

the surface pressure is between 20 bar and 24 bar for a period of 60 seconds to 300 seconds and thereafter

The surface pressure is between 21 bar and 25 bar for a period of 60 seconds to 300 seconds.

The process of any one of Examples 1-9, wherein

the bundle of wood veneers comprises a first veneer and a second veneer which:

no other veneer is left between the first and second veneer, and

the fiber directions of the first and second wood veneers are parallel or the fiber directions of the first and second wood veneers are oriented such that an angle of less than 20 degrees is left between the fiber directions of the various wood veneers.

The method of any one of Examples 1-10, wherein

- according to their quality or their moisture content, these turned laths are classified in two classes: wetter and drier, and

pre-drying only said wetter wood veneers according to any one of Examples 1-10;

preferably, the veneer is classified in the wetter class if and only if the proportion of the moisture content thereof and the dry matter content thereof is greater than a limit value;

preferably said threshold is between 40% and 80%.

A method of making wood veneers, wherein

- turning wooden veneers of wood so that at least 75% of the veneers are long-headed to form turned long-headed veneers, and

pre-drying at least some of said turned long-headed veneers 35 according to any one of Examples 1-11.

20155433 prh 08 -06- 2015

The method of Example 12, wherein

incubating the wood before turning it by soaking the wood in the solution for at least 12 hours, which:

the solution contains water and:

- the temperature of the solution is at least 20 ° C;

optionally introducing said liquid into said solution.

The method of Example 12 or 13, wherein

- incubate the wood with water vapor before turning it.

A method of making wood veneers, wherein

according to one of Examples 1-14, a pre-dried bunch of wood veneer is prepared,

- disassembling the bundle of wood veneer to form individual pressed wood veneers,

- drying individual wood veneers with a drying gas at a temperature of at least 150 ° C for at least 90 s.

The method of Example 15, wherein

- making available additional veneer logs which have not been pre-dried by purchase of pu20,

- drying said individual wood veneers, which have not been pre-dried by compression, with said drying gas for said period.

The method of Example 15 or 16, wherein

- drying the wood veneers so that after drying at least 75% of the wood veneers have a moisture content of less than 7%; advantageously

- at least 5% of wood veneers have a moisture content of at least 3%.

The method of any of Examples 15-17, wherein

- after drying, measure the moisture content of the individual veneer,

- detection of a moisture content exceeding the limit value, and

- drying said wood veneer again with a drying gas.

The method of any one of Examples 1-18, wherein said wood is spruce or birch.

20155433 prh 08 -06- 2015

A process for the manufacture of a layered wood product, wherein:

preparing a pre - dried or dried veneer according to one of the methods of Examples 1 to 19; and

- attaching said veneer to the product blank; advantageously

- said product is parquet or plywood.

Apparatus suitable for pre-drying a bundle of veneer by compression, comprising the apparatus

- a first surface forming a two-dimensional part of the plane,

a second surface forming a two-dimensional part of the plane, said second surface being parallel to and at least partially aligned with the first surface, leaving a space between the first surface and the second surface for the material to be compressed such that the first surface and the second surface room,

- means for moving the first surface towards the second surface and / or for moving the second surface towards the first surface to apply the surface pressure to the material in said space and to compress such material,

means for adjusting said surface pressure, which:

- (i) means for moving the first surface towards the second surface and / or moving the second surface towards the first surface to apply surface pressure to the material in said space and (ii) adjusting said surface pressure to adjust said surface pressure to at least a first value and a second value at least 1 bar and at most 13 bar, and said second value is more than 13 bar and at most 100 bar, and

means for moving the first surface away from the second surface and / or moving the second surface away from the first surface to form said space after compression.

The apparatus of Example 21, wherein

- the first surface and the second surface are movable to move the first surface of the means away from the second surface and / or to move the second surface away from the first surface at least 1000 mm apart, and / or

20155433 prh 08 -06- 2015

- means for moving the first surface towards the second surface and / or for applying the second surface to the first surface to apply surface pressure to the material in said space are arranged to move the surfaces towards each other at a distance of at least 800 mm,

- the device is suitable for pressing multiple bundles of wood veneer in different thicknesses.

The device of Example 21 or 22, wherein (A)

said first surface comprising one or more portions, and

said first surface portion or said first surface portion having a total surface area of at least 1 m ² ; preferably at least 2 m ² and / or (B)

said second surface comprising one or more portions, and

- said second surface area or said combined surface area has a surface area of at least 1 m ² ; preferably at least 2 m ² .

The apparatus of any one of Examples 21 to 23, wherein

- means for moving the first surface towards the second surface and / or for applying the second surface to the first surface to apply surface pressure to the material in said space, comprising at least four hydraulic cylinders to achieve uniform and sufficiently high compression.

The apparatus of any one of Examples 21 to 24, wherein

- (i) means for moving the first surface towards the second surface and / or moving the second surface towards the first surface to apply surface pressure to the material in said space and (ii) means for adjusting said surface pressure to adjust said surface pressure such that

- the surface pressure in the center of said space is higher than in the periphery of said space.

The device of Example 25, wherein

- means for moving the first surface towards the second surface and / or moving the second surface towards the first surface are arranged to move at least the first surface towards the second surface,

20155433 prh 08 -06- 2015

the first surface is the surface of the body and

- at least a portion of the means for moving the first surface towards the second surface are arranged to exert a force in the central region of the body.

The apparatus of Example 26, comprising

- a hydraulic cylinder arranged to exert a force in the central region of said body.

The apparatus of any one of Examples 21 to 27, wherein

- the first surface and the second surface are horizontal,

- during compression, the first surface is arranged to be movable and the second surface is arranged to remain stationary with respect to the ground, and

- the first surface is above the second surface.

The apparatus of any one of Examples 21 to 28, comprising

- means for moving the bundle of wood veneer into said space.

30. The apparatus of Example 29, wherein

said second surface comprising portions of the second surface such that at least two parallel gaps remain between said portions of said second surface, the device comprising

means for moving a bundle of wood veneer into said space, and

- at least part of the means for transferring a bundle of wood veneer to said space are arranged in said slots.

The device of Example 30, so arranged that

- when the device is not used for compression, at least a portion of said means for moving a bundle of wood veneer into said space rises upwardly from said slots, and

when used for compression, said means for moving a bundle of wood veneer into said space are pressed into said gaps and do not rise from the gaps.

The apparatus of any one of Examples 21 to 31 comprising

- a display unit arranged to display the surface pressure or desired surface pressure exerted by the device on the material in its state, and

- at least one button for adjusting the current or desired surface pressure.

The device of any one of Examples 21-32 comprising

a control unit which is arranged

- applying said surfaces to a material in the space having a surface pressure of • at least 1 bar and at most 13 bar for at least 2 seconds, and thereafter • at greater than 13 bar for at least 150 seconds during one or more time periods and at most 100 bar.

34. An arrangement comprising

a device according to any one of Examples 21 to 33, and

- a lathe, the blade of which is provided for turning a long-headed wood veneer15.

Claims (15)

Claim: A method of pre-drying a veneer stack (110) by pressing, in which method 5 - several turned veneer sheets (102) are provided on hand, which together contain moisture and dry matter such that the ratio between the mass of said moisture and the mass of said dry substance is at least 45%. - at least twenty said veneer sheets (102) are assembled on top of each other in a veneer stack (110), the veneer bundle (110) containing moisture and dry matter so that The ratio between the mass of said moisture and the mass of said dry substance has a first value, - at least part of said veneer stack (110) is arranged between a first surface (210) and a second surface (220), said first surface (210) forming a two-dimensional part of a piano and the second surface (220) forming a two-dimensional part of one 15 piano, the first surface (210) is moved toward the second surface (220) and / or the second surface (220) is moved to the first surface (210) to subject the veneer bundle (110) to a surface pressure for pressing and pre-drying the veneer bundle (110 ) by pressing, - the veneer bundle (110) is subjected to a surface pressure through said surfaces (210, 220), which surface pressure is at least 2 seconds eat at least 1 bar and maximum 13 bar and thereafter • over 13 bar for at least 150 seconds for one or more periods and 25 not exceeding 100 bar, whereby - liquid is squeezed from the veneer stack (110), and - the veneer bundle (110) is pre-dried by pressing so that the pressed veneer bundle (110) contains moisture and dry matter such that the ratio between the mass of moisture in the pressed veneer bundle (110) and the mass of dry substance in The pressed veneer stack (110) has a second value that is at least 10 percentage points less than said first value, characterized in that - said surface pressure is always at most 30 bar. The method of claim 1, wherein - said surface pressure is always at most 25 bar. 20155433 prh 18-01-2018 The method of claim 1, wherein - said surface pressure is over 45 bar for at least 120 seconds. A method according to any of claims 1-3, wherein - the surface pressure is at least 15 bar for at least 120 seconds and - the surface pressure thereafter is at least 20 bar for at least 120 seconds. The method according to any of claims 1-4, wherein The 10 surface pressure is 5 bar - 8 bar for at least 5 seconds, preferably at most 3600 seconds; - the surface pressure is preferably 5 bar - 8 bar for at least 5 seconds before the surface pressure exceeds 13 bar for the first thread. 15 A method according to any of claims 1-5, wherein the surface pressure has such a spatial profile that the surface pressure is greater in the middle region of the veneer stack (110) than in the edge region of the veneer stack (110). The method according to any of claims 1-6, wherein 20 - said turned veneer sheets (102) are classified according to their quality or their moisture content into two classes: humidifier and dryer, and - only said moistened veneer sheets are pre-dried according to any of claims 1-5; a veneer blade is preferably classified in the more humid class when and only When the ratio between the mass of its moisture and the mass of its dry matter has a value exceeding a limit value; said limit value is preferably between 40% and 80%. A method of manufacturing veneer sheets (102), wherein - Veneer blades (102) are turned from wood so that at least 75% of the veneer blades are elongated, whereby turned elongated veneer blades are formed, and - at least some of said lathe elongated veneer blades are pre-dried according to any of claims 1-7. 35 A method of manufacturing veneer sheets (102), wherein 20155433 prh 18-01-2018 - a pre-dried veneer stack (110) is manufactured according to any of claims 18, - the veneer bundle (110) is dissolved to form individual pressed veneer sheets (102), 5 - individual veneer blades (102) are dried with dry gas at a temperature of at least 150 ° C for at least 90 seconds. The method of claim 9, wherein - also such veneer blades (102) are provided on hand which have not been pre-cut by pressing, - even those individual veneer sheets that have not been pre-dried by pressing are dried under said drying gas for the said time. Apparatus (200) suitable for pre-drying a veneer bundle (110) by pressing, comprising: - a first surface (210) forming a two-dimensional part of a piano, a second surface (220) constituting a two-dimensional portion of a tab, and said second surface (220) being parallel to said first surface (210) and at least partially opposite said first surface (210), thereby forming a space (202) ) Between the first surface (210) and the second surface (220) for materials to be pressed so that the first surface (210) and the second surface (220) define said space (202); means (212) for moving the first surface (210) to the second surface (220) and / or for moving the second surface (220) to the first surface The surface (210) for directing a surface pressure on the material in said space (202) and for pressing this material, means (310, 212) for controlling said surface pressure, which - (i) the means (212) for moving the first surface (210) to the second surface (220) and / or for moving the second surface (220) to the first surface (210) for directing a surface pressure to the material in said space, and (ii) the means (310, 212) for controlling said surface pressure are arranged to regulate said surface pressure at least to a first value and a second value, said first value being eating at least 1 bar and a maximum of 13 bar, and any other value exceeding 13 bar and a maximum of 100 bar, 20155433 prh 18-01-2018 - means (212) for moving the first surface (210) away from the second surface (220) and / or for moving the second surface (220) away from the first surface (210) to form said space (202) after pressing and - a control unit (310) arranged to expose the material to the space 5 (202) for a surface pressure through said surfaces (210, 220), characterized in that - the control unit (310) is arranged to expose the material in the space (202) to a surface pressure through said surfaces (210, 220), which surface pressure is for at least 2 seconds for at least 1 bar and at most 13 bar and thereafter • over 13 bar for at least 150 seconds during one or more periods and • at most 30 bar. The device (200) of claim 11, wherein - the first surface (210) and the second surface (220) are movable with the means (212) for moving the first surface (210) away from the second surface (220) and / or for moving the second surface (220) ) away from the first surface (210) to a distance of at least 1000 mm from each other and / or - the means (212) for moving the first surface (210) to the second The surface (220) and / or for moving the second surface (220) to the first surface (210), to expose the material in said space (202) to the surface pressure, is arranged to move the surfaces at least 800 mm to each other, whereby - the device is suitable for pressing several veneer bundles (110) of different thicknesses. The device (200) of claim 11 or 12, wherein (A) said first surface (210) comprises one or more parts, and - the surface area of said first surface (210) portion or the total surface area of said first surface (210) portion is at least 1 m ² ; preferably at least 2 m ² , and / or (B) - said second surface (220) comprises one or more parts (221, 222, 223), 35 also 20155433 prh 18-01-2018 - the surface area of said second surface (220) portion or the total surface area of said second surface (220) portion (221, 222, 223) is at least 1 m ² ; preferably at least 2 m ² . 5 Device (200) according to any of claims 11-13, wherein - (i) the means (212) for moving the first surface (210) to the second surface (220) and / or for moving the second surface (220) to the first surface (210), to expose the material to said surface space (202) for the surface pressure, and (ii) the means (310, 212) for controlling said surface pressure are arranged to regulate 10 said surface pressure say that - the surface pressure is higher in the middle area of said space (202) than in the edge area of said space (202). Device (200) according to any of claims 11-14, wherein - the first surface (210) and the second surface (220) are parallel to the horizontal plane, - during pressing, the first surface (210) is arranged to be movable and the second surface (220) is arranged to remain in place relative to the ground, and - the first surface (210) is above the second surface (220). The device (200) of claim 15, wherein said second surface (220) comprises portions (221, 222, 223) of said second surface such that there is at least two parallel gaps (224, 225) between said portions (221, 222, 223) of said second surface, said device (200 ) includes Means (424, 425) for moving the veneer bundle (110) into said space (202) and - at least part of the means (424, 425) for moving the veneer bundle (110) into said space (202) is arranged in said columns (224, 225).