EP1829657A2 - Method for continuously manufacturing composite panels, and a prepress for carrying out the method - Google Patents

Abstract

The method involves providing a swelling compression force in a pressing good mat (10) in a compression zone (12) from a contact of the pressing good mat with an upper compression band (2) up to a main compression line (14). The compression force rises from one swelling maximum to a next swelling maximum along a monotonous rising line up to the main compression line. A boundary of the compression zone to a discharge zone (13) is represented by the main compression line. The main compression line is located in a plane through longitudinal axes of main compression rollers (7, 8). An independent claim is also included for a prepress for compressing an endless pressing good mat made of scattered chips, fibers or particles.

Description

The invention relates to a method for the continuous production of material plates according to the preamble of claim 1. The invention further relates to a pre-press for carrying out the method according to the invention.

Such a method and apparatus of which the invention is based is known from DE 27 28 660 A1 already known. Accordingly, to be deaerated and compacted directly after the formation of a scattered Pressgutmatte. Immediately thereafter, the compacted pressed material mat is compacted in a compacting unit, usually a continuously operating double belt press or a calender press, by means of pressure and heat to form a wood-based panel and cured. The pre-press used here consists of a belt for venting, which circulates endlessly below the press material mat a venting belt and above the pressed material mat a solid endless circulating belt. The breather belt is thereby over a Pulled table to a pressure roller and the upper solid belt is supported with rollers.

The industry has been open to the continuous process for the production of material panels for years and it has already published a variety of patent and non-patent literature for such processes. In addition to an active pre-compression by means of suction of the excess contents of the pressed material mat other process variants have become known, which play a role in the pre-compression. For example, it is from the DE 44 41 017 A1 Not only does the press material mat during the pre-compression vent, but also with process gases to flood, such as superheated steam or superheated steam. Such influences on the thermal and other properties of the pressed material mat are intended to positively influence and improve the pressing factor and thus the possible production quantity of the continuous production process.

Although the design effort of the above pre-press has been proven in practice, it is now no longer necessary to intervene in the structure and in the parameters of the scattered Pressgutmatte in most industrial processes, since the process parameters for the pressing and curing already with the highest Efficiency in the processes before the dispersion of the material to be pressed can be adjusted to the forming belt. In the meantime, the task of the pre-press is focused on the smoothest possible process flow with few production-related To ensure disturbances and to be able to use not only low wear but also high pressures during pre-pressing. Due to their structural design, however, the above prepressing is not able to apply specific pressures or line pressures of more than 100 N / mm to the pressed material mat. Especially with a long table-like support undergoes the compression and / or the venting belt such high tensile stresses that it is destroyed spontaneously or after a short wear. The currently available and available ventilation belts have a maximum tensile stress of 20 N / mm, so that can not be compressed with high pressures. Is not vented or compacted over a solid support, rolling supports are used in the form of arranged over the width of the pressed material compaction compression rollers for the compression bands. In order to provide appropriate pressures for compaction, the compaction rollers must have a minimum diameter of 200 mm. However, this results in a high support distance in the main compression region of a pre-press at maximum compression force, which leads to a wave-like compression pattern of the pressed material mat. Due to the wide support distances of more than 200 mm, the pressed material mat presses the compacting belt between the compaction rollers upwards until it is again guided against the pressed material at the subsequent compacting roller at the radius of the roller in order to compact it. Especially in the area of the strongest compaction of the pressed material mat, this leads to excessive loads and wear of the compacting belt.

In addition, these known pre-presses have the problem in common that the pressed material mat is relieved spontaneously after the pre-compression usually at the radius of the last deflection drum of the corresponding compression belt. Due to the highly elastic compression of the pressed material mat creates a high internal counter pressure from the non-plastically deformed material, which requires that after a pre-pressing and concomitant reduction of Pressgutmattenhöhe to 25% of the scattering height of the pressed material mat back to 50% to 80% of the original scatter height springs back. This creates cracks or fractures in the structure of the compacted pressed material mat, which can expand in the course of the process during the transfer from the forming belt to the next conveyor belts. Also, the transfer of a partially inhomogeneous Pressgutmatte on the steel bands of a continuously operating press can cause problems in the compressing inlet wedge, as unforeseen air inclusions tend to cause blowers against the direction of production when exposed to high pressure and temperature. This results in partial Pressgutmattendoppelungen which can lead to damage to the endless rotating steel bands at high specific pressures. In case of non-occurrence of such problems, the compression of a cracked or broken inhomogeneous pressed material mat may turn out to be a defective surface or a potential break in the finished plate.

The invention is based on the object, a method of the type mentioned in the preamble so that a gentle pre-compression of Pressgutmatte in Hauptverdichtungsbereich allows the compression belts are subject to less wear and the discharge of Pressgutmatte is so gently relieved in the outlet of the pre-press that no cracks or potential breakages in the pressed material mat arise.

The solution to this problem is given for the method in the characterizing part of claim 1, while the solution for the pre-press emerge from the characterizing part of claim 12.

The solution for the method is that in the compression zone from the contact of the Pressgutmatte with the upper compression belt to the main compression line a swelling compression force is introduced into the Pressgutmatte, wherein the compression force increases from a threshold maximum to the next threshold maximum along a monotonously rising line to the main compression line , wherein the main compression line represents the boundary of the compression zone to the relief zone with a compression maximum of the pressed material mat, wherein the main compression line is in the plane through the longitudinal axes of the main compression rollers and wherein after the main compression line Compression force is reduced to 0 N / mm ² except for a technical exception along a monotonous discharge line.

The solution for a pre-press according to the invention for carrying out the method is that the main compaction of the pressed material at the end of the compaction zone a comparison with the compression rollers enlarged Hauptverdichtungswalze are arranged with opposite Hauptverdichtungswalze, and wherein after the two main compaction rollers at the top and / or bottom outlet plates are arranged.

The compression bands (forming or venting bands) are very soft, which causes both at an even low specific pressure between two support points sag (buckling) and the pressed material mat is partially relieved even on both sides and put back on the next compression roller, so are rolling. Such a flexing work may well have advantages in terms of compression of the pressed material mat, but increases above average wear of the machine elements and is harmless only at the beginning of compaction in the pre-press, since the counter-pressure forces from the Pressgutmatte out not so strong that the flexing work on Compaction belt could significantly affect the fatigue strength. The fulling with a bulging of the compaction belts in total over 10 mm leads to cracks in the pressed material mat, if they are during the discharge of the pressed material mat is carried out. Thus, especially thicker pressed material mats are in the chipboard production endangered by the bulging, since they rebound by up to 40 mm after the main compression again. Thin chip mats for board thicknesses below 10 mm are less endangered because the mat height below the main compressor roller is only approx. 10 - 20 mm and after complete unloading approx. 20 - 40% thicker, thus relieved by 3 - 8 mm. This means that after compaction, the mat must be kept under a controlled specific pressure and, at the same time, gently relieved. The Walken (bulging of the bands between the rollers) can not be completely reduced as already described above by an increase in the belt tension, which promotes an increase in the flexing, the tensile stresses and thus the internal wear of the venting belt. The friction on the compression drums also increases significantly. Because with an excessive increase in the belt tension, the compression belts usually tear at the seam. To make matters worse, that the belt tension can not be arbitrarily increased in a lower mold belt, because mold belts can be applied usually only with a belt tension of less than 15 N / mm. Forming belts are usually assembled in the production plant on site to form an endless belt and thus contain joints of weak quality. Next, the space in the scattering rarely allows a complex design of the Formbandförderanlage and therefore can not be too elaborately designed to accommodate high band tensions.

When using the pre-press according to the invention, almost no deflection occurs during compression and release in the case of an upper compression band. This is done by the arrangement of an oversized Hauptverdichtungswalze, which leads in the high-pressure compression area the venting belt over a large peripheral portion to the main compression line and evenly pressurized, on the other hand, the venting band is guided in the venting area on a plate with equally uniform force application, as long act high forces. In the front area of the pre-compaction and at the end of the outlet, the usual roller arrangements can support and guide the venting band, since here the specific pressures are no longer so high that the compacting bands significantly bulge. In principle, the mat is not actively compacted on the forming belt side from below. Therefore, the lower main compression roller facing the upper main compression roller may have a smaller diameter or may be the same diameter as the main compressor roller. Since the lower compression band may not bulge too far after the main compaction rollers, it is also useful here to provide a discharge plate. If the precompression zone with the compaction rollers is not hinged to the main pressure roller, with the same mat height and the same height of the main pressure roller, but different inlet height of the supercharger of the booster in the mat or retracted. If the top spout can be fixed according to the height, the pressure can be kept constant on the Pressgutmatte with different position of the precompression zone.

The height adjustability of the upper outlet plate for pressure control on the pressed material mat has the further advantage that the frictional forces in the region of the outlet plates can be controlled on the compression bands. If too much specific pressure is applied to the outlet plates, the belt friction can become so great that the drives can no longer transmit these tensile stresses by means of the drums. The drive drums then rotate or the compaction belts break because too high tensile stresses are applied. The outlet plate is preferably made with a thickness of 10 mm and a length of 250 - 450 mm. In the inlet and outlet, a radius is provided for smoothly sliding the compacting belts. The compression belts are preferably driven on the upper main compressor roller and the lower counter roller, since there the highest contact forces are present. The driven compression rollers may be rubberized to increase friction, thereby transmitting more drive power.

Since the drive is provided in the main compressor roller, the compression belt is pulled smoothly in front of the main compressor roller because there are the highest belt tensions. The belt tension in the post-compression zone and under the outlet plate is applied in the return.

Alternatively, a rolling support, similar to a carpet may be provided to an outlet plate, whereby lower frictional forces are exerted on the compression belt. However, the rolling support must be equipped with such small rollers that they do not allow significant deflection of the compression straps and requires higher technical effort, since these roles either all have to be supported again with rolling abutments or a flat support of the roles this own circulation need. Depending on the application, only an outlet plate can be provided below. In this case, the compression band would have to be tightened more in the relief zone, if this is permissible in a strength analysis.

Further advantageous measures and embodiments of the subject matter of the invention will become apparent from the dependent claims and the following description with the drawing.

Figur 1

In einer schematischen Seitenansicht den Aufbau einer Vorpresse,

Figur 2

eine nochmalige Seitenansicht der Vorpresse nach Figur 1 mit Darstellung der Verdichtungskraft in Durchlaufrichtung und

Figur 3

eine vergrößerte Darstellung der oberen Maschinenelemente in der Entlastungszone.

Show it:

FIG. 1

In a schematic side view the structure of a pre-press,

FIG. 2

a second side view of the pre-press according to Figure 1 showing the compression force in the direction of passage and

FIG. 3

an enlarged view of the upper machine elements in the discharge zone.

FIG. 1 shows, in a schematic side view, the construction according to the invention of a pre-press 1 for carrying out the method. Depending on the structure of the entire production plant for material plates, the compacting belt 3 may be an endlessly circulating forming belt, which begins in the spreading area of the forming stations and until just before the continuous press. The person skilled in the basic structure of such a production plant is a concept, so that neither the forming station for producing a pressed product mat 10 nor the continuously operating press have been shown in the drawing. Of course, such a compaction press can be used in front of a calender press, but also a compaction of pressed material mats 10 before short-cycle press systems would be conceivable, so that after compaction of the Pressgutmatte 10 this would be handed over to an allocation device. Finally, a compression belt 3 can also be used separately only for the pre-press 1; In this case, a forming belt from the spreading area (not shown) transfers the pressed material mat 10 to a compacting belt 3 which revolves only in the pre-press 1 and which, like the upper compacting belt 2, is guided endlessly over deflection rollers 4. After precompression, the pressed material mat 10 is then transferred to a further conveyor belt or directly to the continuously operating press.

Regardless of the execution of the pre-press 1 with continuous forming belt or a separate compression belt 3 this is repeatedly supported below by means of compression rollers 6 in the compression zone. As can be seen from Figure 1, the distance between the two compression belts 2 and 3 narrows in the flow (from left to right) from the inlet roller 5 and thus compresses the incoming Pressgutmatte 10. In this exercise compacting rollers 6 from above and below pressure on the compression belts 2 and 3 off. Towards the end of the compression zone 12 there are two main compaction rollers 7, which are larger than the compaction rollers 6, at the top and 8 at the bottom. In the sectional plane of the two longitudinal axes 15 of the two main compaction rollers there is a main compaction line 14 transverse to the longitudinal extent of the pressed material mat 14. At this point there is also the maximum compression 18, which corresponds to the highest compression of the pressed material mat 10 in the pre-press 1. Thus, the compression zone 12 ends and merges seamlessly into the relief zone 13. After a brief idle without direct support the compression belt 2 is taken over by a discharge plate 9, which ensures a monotonous and uniform discharge of the pressed material mat 10. Depending on the embodiment of the pre-press 1, additional discharge rollers 27 may be provided after the outlet plate 9, before the compression belt 2 is deflected via the outlet roller 29 and guided again in the direction of the inlet roller 5 via the deflection rollers 4. This makes it possible to compress a wide range of press material mats 10 of various types and heights. In a simpler application can to dispense with the discharge rollers 27 when the outlet plate 9 can cover the occurring rebounds of the different Pressgutmatten 10 optimal. It is also optionally possible, the lower compression belt, depending on the design of the pre-press 1, also support by means of a discharge plate 9 '. This serves as uniform as possible a discharge of the pressed material mat 10 and a prevention of breaks and cracks in a spontaneous springing or a walking relief on back-up rollers in the outlet.

A described in the pre-press 1 technically caused bulge 22 of the pressed material mat 10 after the maximum compression 18 results in the only necessary exception in the otherwise purely monotonous lowering of the compression force at a discharge line. This bulging 10 occurring in the compression zone 12 and the bulge 22 in the relief zone 13 after the main compression roller 7 due to lack of support of the compression belt 2 is shown in detail in FIG. There, a schematic representation of a pre-press 1 is compared with a graph illustrating the compression force of the upper compression belt 2 acting on the press material mat 10 over the path through the pre-press 1. It can be seen that after contact 19 of the Pressgutmatte 19 with the upper compression belt 2, the force increases continuously from the inlet roller 5, wherein Schwellmaxima 20, 20 ', depending on the number and arrangement of the compression rollers 6 occur and between two Schwellmaxima 20, 20' turn the compaction forces go down. This is due to the lack of support of the compression belt 2 and the associated bulges 11 of the pressed material mat 10. In the course of compression, the pressed material mat strikes the main compression roller 7 and is here consciously compressed over a larger segment of the circumference of the main compression roller 7. The present here Hauptverdichtungszone was again marked with 28, it is the place of the highest compression force and the maximum compression 18 of the pressed material mat 10. Here, the main compression roller 7 with a diameter greater than 500 mm a compression travel of 20 mm to reach the maximum compression 18 back , The Hauptverdichtungszone 28 may not have too great a steepness per meter of feed, otherwise the pressed material mat 10 is moved in parts or total and thus inhomogeneities occur. The compaction should not exceed 120 mm / m. This means that with a compression of 20 mm under full force, the diameter of the main compaction roller should be greater than 500 mm, preferably 600-1000 mm. Even the initial compression zone 12 should not come up with too much steepness. Therefore, it is preferable to use a plurality of smaller compression rollers 6, wherein initially, the walking of the compression belts 2 and 3 between the compression rollers 6 under the lower mat back pressures occurs only to a very small extent and thus negligibly.

At the main compression line 14 in a plane defined by the two longitudinal axes 15 of the Hauptverdichtungswalzen 7 and 8, the relief zone begins 13. From here the Pressgutmatte 10 is controlled relieved and a walking or abrupt relief by the employment of a discharge plate 9/9 'to the compression belt 2/3 avoided. The technical exception 21 in the line 17 of the discharge caused by the short bulge 22 of Pressgutmatte between Hauptverdichtungswalze 7 and outlet plate 9. It should be maximum unilateral bulge 22 of the pressed material mat 10 only 5 mm, with a double-sided possible buckling of the material 10 no longer than 10 mm. From this exception 21 there is a purely monotonous lowering of the compaction force along the line 17. The relief zone is not finished directly in the drawing, its length is dependent on the nature of the pressed material mat 10 and results from the point where the pressed material mat 10, the compression belt 2 above no longer touched. In strongly rebounding Pressgutmatten 10, it may be necessary in addition to the outlet plate 9 still order discharge rollers 27. Since in this advanced stage of discharge no large forces act more on the tape tension a monotonous discharge in this area is possible, or a minimally walking discharge is negligible and harmless. Too long an outlet plate 9 could lead to exceeding the permissible tensile stresses on the compression belt 2/3 by the resulting friction. FIG. 3 describes an optimum structure of the relief zone. For this purpose, the outlet plate 9 on the inlet side a joint 25 corresponding height adjustable fixed with the main compression roller 7. On the outlet side are actuators 26, preferably double-acting hydraulic cylinder piston assemblies arranged, which can adjust the outlet side of the outlet plate 9 arbitrarily and thus allow a variety of angle settings. The optional relief rollers 27 can be manipulated separately via their own actuators or directly with the actuators 26.

In order to carry out the discharge in accordance with the specifications of the method properly various sensors 23, depending on the need, attached to the outlet plate 9, possibly also on the main compression roller 7 and / or on the corresponding parts of the compression belt 3. About a control device 24 with storage and adjustment options, the angle of the Auslaufbleches 9 can be controlled automatically via the actuators or readjusted manually. Of course, there are more control options, such as. Example Control of the height of the main compaction rollers, the unloading line or the height of the inlet roller 5 or the roller 29 Further, the metrological or technical control requirements are not discussed, but they can be found in the relevant regulations. With regard to the control, a displacement or a pressure control can be used so that no sudden relief of the compression force within a few millimeters of relief zone 13 can occur. Preferably, the slope of the Relief line 17 are regulated so that no more than 2 mm mat height per 10 mm feed are relieved.

In a further embodiment, a further support of the compression belt 2 in front of the main compression roller 7 or 8 may be necessary in prepressing with high compression pressures. For this purpose, either support rollers 31 or support plates 30 may be arranged, of course, as required, corresponding to the compression belt 3 in analogous application. Of course, these must be adapted to the installation space between the compaction rollers 6 and the main compaction rollers 7, 8. Preferably, the main compaction roller should have a diameter of more than 500 mm.

List of Reference Numerals: DP 1321EP

1.

pre-press

Second

compression band

Third

compression band

4th

deflecting

5th

inlet roller

6th

compaction roller

7th

Main compaction roller

8th.

Main compaction roller

9th

delivery plate

10th

press material mat

11th

Buckle of 10

12th

compression zone

13th

relief zone

14th

Main compression line

15th

Longitudinal axis of 7/8

16th

Line of threshold maxima

17th

Line of relief

18th

maximum compression

19th

Contact 10 with 2

20th

Schwellmaximum

21st

exception

22nd

upheaval

23rd

sensor

24th

control device

25th

joint

26th

actuators

27th

relief rolls

28th

Main compression zone

29th

deflecting

30th

gusset

31st

backup rolls

32nd

transport rollers

33rd

Threshold maximum at 7

Claims (22)

A process for the continuous production of material plates, but primarily for the production of particleboard, fiber or particle plates, in which in a molding area of chips, fibers and / or particles, optionally mixed with binder, formed on a continuously moving forming belt a Pressgutmatte This press material mat is brought into a final shape and cured after precompression and possibly preheating between the molding area and a main press area using pressure and heat in the main press area, wherein the pre-compression is performed between two endlessly circulating compression bands, which is characterized in that
in the compression zone (12) from the contact (19) of the pressed material mat (10) with the upper compression belt (2) to the main compression line (14) a swelling compression force is introduced into the Pressgutmatte (10), wherein the compression force of a Schwellmaximum (20) to the next threshold maximum (20 ') along a monotonously rising line (16) to the main compression line (14) increases, wherein the main compression line (14) the boundary of the compression zone (12) to the discharge zone (13) with a compression maximum (18) of the press mat (10), wherein the main compression line ( 14) in the plane through the longitudinal axes (15) of the main compression rollers (7, 8) and wherein after the main compression line (14) the compression force except for a technical exception (21) along a monotonously extending relief line (17) to 0 N. / mm ^{2 is} reduced. A method according to claim 1, characterized in that the last threshold maximum (33) in the compression zone (12) over the radius of the main compression roller (7) to the main compression line (14) is controlled and thereby sets the compression maximum (18) of the pressed material mat (10) , A method according to claim 1 or 2, characterized in that due to the technical exception (21) in the relief zone (13), the maximum unilateral curvature (22) of the pressed material (10) is 5 mm, with a possible bulging of the pressed material (10 ) not more than 10 mm. A method according to claims 1 to 3, characterized in that by a corresponding design and selection of the discharge line (17) in the discharge zone (13) no sudden relief of the compression force is carried out within a few mm discharge zone. Method according to claims 1 to 4, characterized in that for adjusting a monotonically decreasing relief line (17) and thus a monotonically decreasing compression force the compression belts (2, 3) after leaving the main compression rollers (7, 8) by means of a planar abutment, for example an outlet plate (9, 9 ') are guided and held. Method according to claims 1 to 5, characterized in that the position of the outlet plate (9) is regulated by way. Method according to claims 1 to 5, characterized in that the position of the outlet plate (9) is regulated by the contact pressure. Method according to claims 1 to 5, characterized in that the position of the outlet sheet (9) over the Back pressure from the pressed material mat (10) is regulated. Method according to claims 1 to 8, characterized in that the slope of the relief line (17) in the relief zone (13) is not more than 2 mm per 10 mm length of the compacting belt (2) Process according to claims 1 to 9, characterized in that at the end of the compression zone (12) a compression takes place in a main compression zone (28) along the radius of the main compressor roller (7). Process according to claims 1 to 10, characterized in that with a diameter of more than 500 mm of the main compaction roller (7), a compression path of 20 mm to the maximum compression (18) takes place. Prepress for compacting an endless pressed material mat of scattered chips, fibers, particles or the like, consisting of two endlessly circulating compression bands and the associated deflection drums, wherein top and bottom for the application of compaction forces compaction rollers are arranged,
characterized in that the main compression of the Pressgutmatte (10) at the end of the compression zone (12) opposite the compression rollers (6) enlarged Hauptverdichtungswalzen (7) and this opposite Hauptverdichtungswalze (8) are arranged, and wherein after the two main compression rollers (7, 8) top and / or bottom outlet plates (9) are arranged. A pre-press according to claim 12, characterized in that the enlarged main compression roller above has a diameter of more than 500 mm. Prepress according to claim 12 or 13, characterized in that a permeable venting band is arranged as upper compression band (2). Prepress according to claims 12 to 14, characterized in that the lower compression belt is simultaneously arranged as a forming belt for producing the pressed product mat (10) in the spreading area and / or as a transfer belt to the continuously operating press. Prepress according to claims 12 to 15, characterized in that the outlet plate (9) on the side of the Main compression roller (7, 8) in height corresponding to the acquisition of the compression belt (2, 3) is arranged. Prepress according to claims 12 to 16, characterized in that for adjusting the slope of the relief line (17) on the outlet side of the outlet plate (9) a joint (25) and outlet side actuators (26) are arranged. Prepress according to claims 12 to 17, characterized in that arranged in the region of the outlet plates (9) sensors (23) for travel and / or pressure. Prepress according to claims 12 to 18, characterized in that a control device (24) for adjusting the relief line (17) of the outlet plate (9) on the basis of the measured values of the sensor (23) and a stored reference variable is arranged. Prepress according to claims 12 to 19, characterized in that between discharge plate (9) and guide roller (29) additional discharge rollers (27) are arranged. Prepress according to claims 12 to 20, characterized in that in the outlet plate (9) holes are arranged. Prepress according to claims 12 to 21, characterized in that the rear circulation rollers (29) for the circulating compression bands (2, 3) are arranged vertically adjustable.

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