DE2024038A1 - Compressed cellulose fleece panels - Google Patents

Abstract

Panels are formed by compressing a fleece of cellulosic particles which is produced from two subsidiary fleeces arranged in a mirror image manner to a perpendicular. Gives symmetrical panels with similar properties on both sides of their central plane. A different core material may also be introduced between the two subsidiary fleeces.

Description

Method and apparatus for the production of panels from cellulose discs Particles "The invention relates to a process for the production of plates which are pressed from a fleece made up of cellulosic particles.

Depending on the manufacturing process, such panels are at their center plane more or less asymmetrically constructed. The plates therefore face on both sides unequal characteristics.

The invention is based on the object of avoiding these disadvantages. In particular, a method and a device are to be developed by that can be made of panels that are symmetrical about their center plane are.

This object is achieved according to the invention in that the fleece made of two identical partial fleeces arranged in mirror image to a perpendicular will be produced. The partial fleeces are preferably on approximately horizontal ones Supports formed, then the partial fleeces expediently in the perpendicular to the to be compressed fleece are combined.

An advantageous method is given when the two partial fleeces subjected to equalization and X or weight correction prior to their union will. Yliose leveling is allowed on the surfaces of the two partial fleeces at the same time an immediate and symmetrical volume and weight correction Removal of the excess chip material .. This can cause too thick, or at the same time Activation of a weight correction by weighing1 moldings that are too heavy from the start be avoided. The balancing can also be used together with weighing immediate or even advance control of the spreading station can be used 1 so that excesses that are too high are reduced, while excesses that are too low are built up will.

With the new process, it is also possible to place between the two partial fleeces before they are united, a middle core fleece constructed symmetrically to the vertical or other foreign materials to be fed in 0 With an appropriately designed device the requirements for the partial nonwovens are necessary for carrying out the method according to the invention designed as endless smooth belts or sieve belts.

These can also be advantageous after the partial webs have been brought together as wrapping tapes for the fleece are used, which protect the fleece against external influences shield and hold it together.

The tapes can also be used with the fleece through the prepress, if necessary also run through the hot press.

The one at the transition of the fleece halves into the perpendicular with little matting and stickiness of the sellulosic particles has a tendency to slip off the Fleece halves or to shifting the structure in the fleece halves or on their surfaces can be prevented by suitable devices. For example, on Both sides of the fleece aprons are provided with the appropriate tension press against the surfaces.

So that the fleece surfaces are under the holding pressure of such aprons not so flat that the interlacing of the chips and, as a consequence, the transverse tensile strength The aprons can also drop below the usual level with suitable baffles be provided.

That which emerged after the two partial fleeces had been brought together in the perpendicular Fleece can be continued and pressed in various ways. For example a hot press working in the vertical can be provided, the press plates each have the same distance from the molding 0 During the introduction of the Fleece or pre-pressed part and during the pressing plate fleece movement prevail thereby the same conditions in each case on the surfaces of the molding.

Below are some advantages of the method according to the invention contrasted with the corresponding disadvantages of the previous procedures: In the Fleece formation for flat pressed chipboard according to the previous process causes the ntmixtt an asymmetrical distribution of the fine material $ as a result of gravity the finest material of the upper half of the fleece is removed from the top, the finest material the lower half of the fleece approaches the underside of the fleece.

The same is true when powdery foreign materials, e.g.

Fire retardants, for example on the outsides or between the top and middle layers of the fleece are brought.

Since in the inventive method, the two fleece halves as mirror images Partial fleeces are formed, the fine material of both partial fleeces trickles equally down to the later outer surfaces, the symmetry is preserved. This advantage However, the method of web formation according to the invention only remains complete obtained when the fleece after the union of the two fleece halves in the perpendicular is also pre-pressed in the vertical.

In the manner corresponding to the force of gravity, it causes the formation of the fleece for fibreboard using the previous drying process, the one under the fleece backing applied vacuum has a fiber orientation that is different just above the base than on the top of the fleece.

Even with the formation of the nonwoven on the wet fiberboard on a sieve pad there is such an asymmetrical fiber orientation.

In the inventive method, the vacuum act in the formation of the dry fiber fleece as well as the force of gravity in the wet fiber web formation on both partial webs equally, the symmetry is preserved.

The dispersion of the chips is subject to fluctuations, which are never completely can be prevented. The resulting thickness and density fluctuations also lead to an asymmetrical behavior of the plate. These disadvantages permit have not yet been resolved by leveling the fleece, since the latter is not symmetrical to the center plane of the fleece in the previous methods can be applied. For example, in the case of a multilayer board level the lower, i.e. first scattered, top layer on its upper side. However, the leveling of the upper cover layer can also only be done on the upper side, however, this cannot be done on the underside, which helps to maintain symmetry would be required.

In the inventive method, on the other hand, the fleece leveling is the same with both partial fleeces and also with all corresponding layers of both partial fleeces possible.

In addition, it is now possible with the fleece leveling a symmetrical weight correction for both partial fleeces and even for all corresponding ones To connect layers of both partial fleeces. The equalization can be done together with a weighing except for the immediate or even for the advance control of the spreading stations be used. This leads to the highest accuracy.

On the one hand, there are other factors that impair the symmetry the temperature of the fleece base1 on the other hand the temperature, humidity and movement the air in the production room and its different effects on the two sides of the fleece.

The inventive method is also symmetrical in this respect Treatment of both fleece halves guaranteed.

According to the previous method, this can be used for the desired stronger Compaction of the outer layers and short pressing times of chipboard required additional surface water in the formation of the fleece is not symmetrically the same Manner.

The inventive method is the symmetrical surface spray - at the same times and under the same conditions - possible in a simple manner. This secured symmetry allows it, especially if the hot pressing in the vertical is done, the surface spraying directly before the hot pressing in maximum Quantities to apply. The surface spraying thus contributes optimally to the fact that the hitherto considerably below the surfaces on both sides and considerably on both sides different bulk density and lift-off strength maxima closer to the surface come, become greater and equal.

Throwing and wind sighting effect change in a scattering station due to the forming fleece thickness. For example, if the lower top layer is scattered The existing clearance between the chip discharge and the fleece underlay is much greater than that remaining after the scattering of the upper cover layer. The resulting Changes in wind conditions also lead to an inevitable asymmetry of the chipboard produced in this way.

In the inventive method, the symmetry is preserved, since wind and litter vision effect are the same in both partial fleeces.

At a standstill and when starting up again and especially with the constant ones Changing the direction of mobile spreading stations for endless fleeces puts the chip curtain down differently on the fleece underlay than during the continuous run. Result from this discontinuity zones. These go diagonally through the thickness of the individual layers and are offset from one another in the layers or fleece halves. You effect hence an asymmetry of the affected panels.

In the inventive method, these discontinuities are always located syiaaetrically to each other in the two halves of the fleece.

In the methods of hot pressing that have been used up to now, the Nonwovens or preforms due to gravity directly or indirectly on the hot lower press plate; the temperature and humidity migration takes place under the influence the hot press plates despite various remedial measures, at least when inserting and asymmetrically when closing the press.

According to the inventive method is the use of a hot press possible in the vertical. This is preferably done in such a way that during the introduction of the fleece or preform and during the closing movement of the press plates to the main surfaces of the fleece or preform have the same distance so that the effects of this process on the compact take place symmetrically.

Compliance with the symmetrical position of the molding between the hot press plates is ensured at the entrance and exit by the guide rollers there. Possibly Further spacers can also be provided in the intermediate area.

The inventive method results in the high accuracy, one of the prerequisites for this is that a subsequent grinding process and The associated workload and material loss are reduced to a minimum or can be saved entirely0 It is of particular importance to them for coating with related (e.g. fiber decks) or alien (e.g. foils) Materials in the incoming process.

The combination of fiber decks with nonwovens in the one-way process has been suggested repeatedly, but has not yet been implemented. Instead of one modifies that with chipboard produced in the usual way with top layers of scatterable "micro chips" or "fiber chips". Certainly could the lower fiber deck can be produced e.g. as a dry fiber fleece on a sieve belt, and in the further process the chip layers could be scattered. The difficulty however, the transfer and application of the necessarily lies with others Place produced sensitive fiber fleece as an upper deck on the chipboard.

According to the inventive method of production in two fleece halves the entry process of chipboard with real fiber decks is no problem. the Both fiber decks are the first layers on the backing for the two fleece halves then the chip layers are scattered.

The two-sided coating in the one-way process with primer or decorative foils, casting resins, etc. is ultimately in the previous nonwoven manufacturing technology unsatisfactory because of the inaccuracies and aaymmetry effects, but also because of the different difficulties in applying the coating on the underside and on the top of the fleece.

All of this is omitted in the inventive method. The coating is carried out on both sides in a simple and symmetrical manner Application to the documents of both partial fleeces.

Finally, the inventive method also offers the possibility of in a simple way between the two partial fleeces before they are united in the perpendicular Insert insoles made of related or dissimilar material symmetrically. Will the pre-pressing is also carried out in the perpendicular1 so can also be rigid Inlays e.g. plasterboard for sound absorbing purposes are introduced.

The disadvantages mentioned for the previous method also apply here to, with heavy middle positions the asymmetry would be exacerbated. Besides the introduction of the middle layer is more difficult in the previous method, for endless ones rigid materials impossible.

In the drawing are some exemplary embodiments shown for performing the method according to the invention.

The figures show: FIG. 1 in a schematic representation a device for Production of partial fleece on horizontal supports and an arrangement for merging of the two partial fleeces in the vertical; Figure 2 in a schematic representation Nonwoven forming system for dry fiber boards that works approximately in the vertical FIG. 3 shows, on an enlarged scale, a forming station with a leveling device to form a partial fleece; Figure 4 in a schematic representation of the formation a partial fleece with a dry fiber cover layer; Figure 5 in a schematic representation an arrangement for coating a Weil fleece with a film and figure 6 shows a representation according to FIG. 1 with an additional core fleece.

According to FIG. 1, a mirror image of a perpendicular 0 becomes a horizontal one Supports 1 partial fleeces 2 and 2 'by corresponding fleece forming devices 3 manufactured. According to the arrows drawn in, these run in the present Example designed as a sieve belts supports 1 on combining rollers 4, the for the production of different panel thicknesses up to the one shown in dashed lines Extreme positions can be shifted. By the rollers 4, the partial fleeces 2, 2 'combined to form the fleece 5. With 6 is a device against slipping together of the fleece halves made of very free-flowing material in the critical steep area. 7 should be one from below through the sieve belts evenly on both partial fleeces 2.2 ' indicate effective surface sprinkling.

FIG. 2 shows a web-forming plant for dry fiber boards.

Here, too, the perpendicular O also represents the plane of symmetry.

The fibers reach the web forming devices via the fiber feed 8 3 and thus in the effective area of an externally applied vacuum 9. As conditions 1 for the partial fleeces 2, 2 'are used sieve belts.

FIG. 3 leaves one half of a system for correcting the middle layer scatter recognize. The support 1, which in turn is designed as a band, migrates with one on it located cover layer 10 of this partial fleece 2 in a scattering station 11. Here forms a chip veil 12 the middle layer half 13, which is then carried out by a spiked roller 14 is equalized. The support belt 1 hangs somewhat between the support rollers 15 and 16 by. The free sag is indicated by a curve 17 shown in dashed lines The slack band rests on the Upper run of a belt scale 18 and loads it according to the unevenly distributed over the span Load. Since the unevenness remains approximately the same, the load on the scales is a measure already obtained in advance for the weight of the later partial fleece. Exceeds this load determines + fluctuations, then the scattering station 51 becomes accordingly corrected. The limit values are set so that the Ggalisiervorrichtung serving spiked roller 14 never too little, but also not too much chip material for Has to equalize. The support rollers 15, 16 are constrained guides 19 and 20 with the support band - for example by cams engaging in holes in the band - Coupled so that the extended length of the hanging between the support rollers Band is always the same with a certain setting of the priority control.

This dimension can be adjusted according to the various panel weights of the Production program can be set to different ratios. The backup rolls 15, 16 are with the belt scale 18 on a common base plate 21 as a unit adjustable in production direction. Should the unrest of the weight of the forming Fleece half will be larger than the one in the finished fleece half and the prediction will be excessive make it difficult, the weighing unit is shifted towards the finished half of the fleece so far that until the resulting decreasing fluctuations on the one hand and the increasing ones Uncertainty from the later weighing, on the other hand, results in optimal conditions.

FIG. 4 shows one half of a system for the formation of a partial fleece 2 with a dry fiber cover layer 22. The support belt 1 designed as a sieve moves under the fiber feed 8 along, the one below the support belt 1 a vacuum 9 is assigned. The support band migrates with the fiber cover layer 22 formed here 1 further under the spreading station 3, where the Fiber top layer the (half) chip center layer 23 of the partial fleece 2 forms. The two fleece halves 2, 2t are brought together in the combining rollers i to form the fleece.

With a device as shown in one half in FIG a film coating can be carried out. The coating film runs in the process 24 from a roll 25. The completely similar working method for coating the two partial fleeces 2, 2t ensures the symmetry. The one after the inventive The high accuracy of the partial fleeces achieved is the prerequisite for the process Satisfactory coating in the entrance process.

According to Figure 6 is between the two partial webs 2, 22 before their Combination of a middle core fleece 26 constructed symmetrically to the perpendicular 0 mug-run.

Claims (8)

Claims. 1. Process for the production of panels from a cellulosic Particles built-up fleece are pressed, characterized in that the fleece (5) of two identical partial fleeces arranged in mirror image to a perpendicular (o) (2,2 ') is produced. 2. The method according to claim 1, characterized in that the partial fleeces (2.2 ') are formed on approximately horizontal supports (1). 3. The method according to claim i or 2, characterized in that the Partial fleece (2.2t) combined in the perpendicular (o) to the fleece to be pressed (5) will. 4. The method according to any one of the preceding claims, characterized in that that the two partial nonwovens (2, 2 ') are equalized and / or before they are combined Weight correction are subjected. 5. The method according to any one of the preceding claims, characterized in, that between the two partial fleeces (2.2t) before they join a middle, symmetrical to the perpendicular (O) constructed core fleece (26) or other foreign materials supplied will. 6. Device for performing the method according to one of the claims 1 - 5, characterized in that the supports (1) as endless smooth bands or Sieve belts are formed. 7 * Device according to claim 6, characterized in that the supports (1) after the union of the partial fleeces (2.2 ') as wrapping tapes for the fleece (5) are trained. 8. Device for performing the method according to one of the claims 1 - 5, characterized by a hot press working in the vertical (0), whose Press plates each have the same distance from the molding.