CZ2001295A3 - Device and method for producing building slab - Google Patents

Abstract

Apparatus for producing layered gypsum fibre board having a conveyor (7) for carrying material through processing stations (4, 5, 6, 8, 10) including a degassing station (8) having lateral barriers (23; 27; 30; 31; 60; 40; 41) to restrict spread of material.

Description

Technical field

The present invention relates to the manufacture of a building board from a setting, binder material. The present invention is particularly useful in the manufacture of gypsum fiber board.

BACKGROUND OF THE INVENTION

The bonded fiber board is manufactured according to a process comprising mixing a predetermined amount of fiber material (e.g., cellulosic fibers or wood chips), water and a dry setting, binder material (e.g., dry calcined gypsum), forming the mixture into a carpet and compressing such a carpet. followed by solidifying the binder material and forming a board of bonded fibers and a solidifying binder material. The fibrous material may be reinforcing fibers. Admixtures may be added to the blend to accelerate the bonding process or to improve the board properties. The amount and type of additive depends on the desired properties of the finished board.

A three-layer bonded fiber board comprising a mixture of fibers, water, curing, binder material, lightweight aggregate such as a sledgehammer and any desired additive can be made using the process described in International Patent Application No. WO93 / 01932 Caria Schenka , which focuses on the method of manufacturing gypsum fiber board.

The uncompressed carpet, which comprises a mixture of fibers, water, a setting material, a binder material and any desired admixture, is formed by casting metered doses of the mixture onto a moving conveyor belt. The mixture is applied to a strip on which a three-layer carpet having a relatively high height is formed. In the blend that makes up this uncompressed carpet, the air content is about 70% to 80% of the total volume. This is known as the 'forming phase'.

The flattened layer of the mixture is then transferred to a continuous-running cylindrical Hsu having three main stations, a pre-press or pre-press (also known as a degassing press), a main press and calibration station. The movable conveyor belt carries a horizontally aligned mixture through the press station, and the mixture undergoes all compression operations.

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At the pre-press station, the air contained in the mixture is removed as a result of the compression, and at the same time the height of the carpet is reduced in connection with preparing the entrance to the main press. The precompression is typically performed using an upper belt which gradually slopes in the direction of movement of the carpet on the movable conveyor. One or both of the belts in the preforming station are breathable so as to allow air to be ejected from the carpet. Upon introduction into the preform, the top of the carpet comes into contact with the top web. The preforming typically reduces the height of the carpet by about 70% (as an example, in the case of a finished board having a 10 mm throat, said height decreases from about 70 mm to about 15 to 20 mm). The carpet leaving the preform has about 120% to 150% of the desired thickness of the finished board. Most of the gypsum at the exit of the pre-press does not start to solidify and when leaving the pre-press it is a compact mixture in the form of a semi-dry, crumbly carpet. After leaving the pre-pressing station, the required amount of water is sprayed onto the compact carpet to ensure complete hydration of the dry gypsum.

The main press exposes the carpet to a high load, which compresses the carpet to the final thickness of the finished board. The main press typically comprises a frame carrying two continuously running belt conveyors, one moving above and the other below the carpet. These belt conveyors are supported on rollers that are spaced at short distances from each other, allowing the conveyors to exert considerable creasing efficiency on the carpet. The gypsum is partially solidified when leaving the main press.

The calibration station is very similar to the main press and can also exert considerable pressure on the carpet. The calibration station is designed to maintain a predetermined thickness of the carpet until the carpet solidifies at the exit of the calibration station. Finally, the gypsum solidification takes place in a calibration station or calibration press, so that the carpet leaving the calibration station takes the form of a solidified plate. Under certain circumstances, the plate that leaves the calibration press may not be completely solidified. At the exit of the calibration press, hydration may not be fully completed, and therefore the next solidification process may continue even after the plate leaves the calibration station.

In a typical gypsum fiber board production plant operating according to the above method and the guidance contained in WO93 / 01932, the pressed, solidified board is trimmed and trimmed to the required parts prior to subsequent drying.

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The edges of the untrimmed board leaving the calibration station will be soft due to the tendency of the carpet mixture to leak to the sides during application and compression. These soft, lateral edges of the molded plate are not suitable for the purpose of using the final manufactured sheet, as they reduce the strength of the sheet and, if left on the sheet, would cause unevenness on the sheet. Therefore, such soft edges must be removed. This is done by trimming the board using a water knife. It has been found that in the above-mentioned gypsum fiber board manufacturing plant in which a molded carpet is formed having a width of approximately 2600 mm, approximately 100 to 200 mm must be cut off from each side edge. This means that approximately 6% to 16% of the pressed material must either be discarded or recycled, which in both cases represents a significant waste of energy. A further disadvantage of this waste is that the width of the plate produced in such a plant must be substantially less than the width of the line equipment belt, and in some cases the maximum possible width of the plate is approximately 400 mm less than the width of the belt used.

Another problem relates to the production of laminated, bonded (e.g. gypsum) fiber boards which are made of layers containing different mixtures.

The gypsum fiber board may be made in a three-layer design that comprises a rigid top and bottom skin layer and a less rigid intermediate layer or core having a lower density. A layered structure is advantageous because it allows the weight of the finished board to be reduced without sacrificing strength in important areas, which are surfaces. The less rigid and lighter core layer is typically made of a gypsum composition comprising a lightweight aggregate such as perlite, vennicite or the like filler. Typically, the core layer has a lower fiber content than is the case with surface layers.

The laminated fiber board is manufactured in a plant which is equipped with means for preparing and supplying gypsum compositions for making the surface layers and setting the layer. The coating layer is applied to the movable conveyor, then the core mixture layer is placed on the first coating layer and finally the topcoat layer is applied to the low weight core layer.

Subsequently, the laminated carpet is pressed, cut, shortened and dried as described above.

In the case of a laminated, bonded fiber board, leakage of the carpet material to the sides during the forming phase, the pre-pressing phase and the main pressing phase causes additional problems

-4-> 9 Φ Φ approach the problems already mentioned, as the leakage of the mixtures to the sides and the adhesion of the surface layers to the compression belts help leaking unstable, lightweight core layer to the bottom of the carpet at its edges. This leakage results in a plate that does not have fixed edge portions over a considerable distance towards the center of the finished plate, as shown in Figures 3 (a) to 3 (f). A finished board having a material of low weight and strength on the surface shows a serious threat to the strength requirement. Therefore, the side edges of the board must be trimmed so that all portions of the board surface to which the low-weight mixture has entered are removed, and such parts are subsequently discarded.

SUMMARY OF THE INVENTION

The present invention is directed to reducing waste associated with the production of bonded fibrous plates in a manufacturing plant in which the still non-solidified binder material is considerably compressed or densified prior to solidification.

The present invention provides a method and apparatus for producing a building board as defined in the independent and other claims, to which reference will now be made. Advantageous features of the invention are defined in the dependent claims.

Preferred embodiments of the present invention allow a significant reduction in waste associated with the production of the known plant of the type described above and in International Patent Application No. WO93 / 01932, without limiting the strength of the finished board.

In addressing this problem, it is suggested that problems associated with board edges could be alleviated by incorporating a rigid barrier that is transverse to the direction of spread of the mixture into the molding station before the mixture enters the press. However, such barriers only partially alleviate this problem with regions.

The present inventors first concluded that much of the material is extruded sideways in the preform. Previously, no attention was paid to the fact that, although the carpet leaving the preforming station was not solidified, the subsequent high-pressure pressing in the master and calibration presses did not substantially push the edges of the carpet sideways. The present invention is based on the discovery of its authors that the critical and major source of side edge extrusion of the carpet is in the pre-pressing stage, although the carpet leaving the pre-pressing station

-5 is not stiff and consequently will have to undergo further manufacturing steps in which they will be prior to solidification on this carpet to exert great pressures.

Significant Improvements The grease of the board edges can be achieved by providing a side barrier in the preform station.

Although it has previously been proposed to create side barriers up to the pre-press phase, these prior art systems have not effectively addressed the edge extrusion problem most commonly encountered during compression in the pre-press phase. Applicants of this invention are the first to evaluate this. As a result, the bonded fiber board produced according to said process, which involves pressing and significantly reducing the thickness during the pressing, in which the side barrier is only applied in the forming station, will have considerably soft edges. As already mentioned, the present inventors are the first inventors who have found that the problem of soft edges can be substantially alleviated by preventing lateral movement of the carpet (i.e., expanding the carpet due to the extrusion of the layer material sideways) in the defatting or pre-pressing phase.

The prior art systems having fixed side barriers in the molding station are also highly ineffective, since the composition containing the setting, binder material tends to adhere to the side barriers and, as a result, deposited material accumulates on the barriers.

The present inventors have found that truly significant improvements are achieved when the extrusion of the material to the sides during the pre-compression phase is prevented. Although the carpet leaving the preform is not solidified, it has a compactness sufficient to make the extrusion of the material in the side of the main press station without side barriers not as significant as the extrusion of the side in the preform without side barriers, even though the main press it exerts more pressure and this pressure is effective for a longer time.

Overview of the drawings

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings, in which:

Fig. 1 shows a method and corresponding technical process equipment for producing a laminated, setting, bonded building board;

Fig. 2 shows a cross-section of a laminated gypsum fiber carpet on the forming belt shown in Fig. 1;

Figures 3 (a) to 3 (g) show a cross-sectional view of half of the laminated gypsum fiber mat at various stages of the production of the laminated building board according to the hitherto known method carried out in the apparatus illustrated in Fig. 1;

Figures 4 (a) to 4 (f) show cross-sections of half of the gypsum fiber mat at different stages of manufacturing one embodiment of a laminated building board according to the present invention;

Fig. 5 shows an embodiment of a side barrier in a preform;

Fig. 6 shows a drive and / or guide system for the barrier illustrated in Fig. 5;

Figures 7 (a) and 7 (b), as well as Figures 8 (a) to 8 (d), show an alternative design of the pre-flanking side barriers;

Fig. 9 shows another alternative embodiment of a preformed side barrier;

Figures 10 (a) to 10 (c) illustrate the compression of the barrier shown in Figure 9 as it passes through the preform station;

Fig. 11 shows an alternative pre-molded side barrier;

Fig. 12 shows the side barrier shown in Fig. 11 when depressed;

Figures 13 and 14 are another alternative embodiment of the preformed side barriers; and Fig. 15 shows an applicable guiding mechanism for the preform side bar shown in Figs. 8 to 11.

DETAILED DESCRIPTION OF THE INVENTION

The following descriptions of the preferred embodiments and the related, appended drawings are for the purpose of explaining and demonstrating the present invention only, and it is therefore obvious that there are other possible embodiments of the present invention. In particular, all the embodiments described relate to the manufacture of a gypsum plaster having a thickness of approximately 10 mm. It will be appreciated that the present invention is applicable to other construction board assemblies having different thicknesses.

In the following examples, a laminated gypsum fiber board is produced by first depositing three layers 1, 2, 3 of three separate mixing heads 4, 5, 6 on a forming belt 7, followed by compression to expel air from the formed three-layer carpet. (typically a 70% reduction in the initial thickness of the carpet is performed) at the preform 8 defined by the upper cover strip 9, which approaches the forming belt 7 and compresses the plate to the final thickness in the main press 10 and the calibration press 20; The method and apparatus for making the described embodiments are modifications of the known manufacturing apparatus according to International Patent Application No. WO93 / 01932, to which this patent application refers for details of the manufacturing apparatus. device and method which are not included in the following description.

In the manufacturing apparatus shown in FIG. 1, moistened recycled paper fibers for the backsheet 1 are laid on a first preform (not shown), followed by applying a layer of gypsum hemihydrate or gypsum mortar together with admixtures. The belt transfers the materials to the mixing head 4, which applies the resulting mixture to the main molding belt 7. Thereafter, water is sprayed on the mixture and this water initiates the gypsum hydration process in the lower surface layer.

The moistened aggregate (for example, perlite or the like low weight material) and fibers for the core layer mixture are fed to a mixer from which the core layer mixture is applied to a second preform (not shown) passing through the mixing head 5 and deposited on top. At the same time, fibers and gypsum are applied to the third preform belt (not shown) for the topcoat layer 3, after which the materials are mixed in the mixing head 6 and subsequently applied to the top of the core layer 2 on the main belt. The layers of gypsum mixtures form a layered carpet.

The web 7 introduces a layered carpet (1, 2, 3) into a pre-press or degassing press 8 which compresses the carpet to a fraction of its original height, and is approximately 30 in the specific embodiments of the present invention which will be described hereinafter. % of the initial height of the carpet. This pre-pressing or degassing pressing expels most of the excess air from the layered carpet.

The densified carpet is then transferred to the belt through a spraying station where the required amount of water is sprayed onto the compact carpet to hydrate any gypsum contained in the carpet further to the main press 10 and then to the calibration press 20.

These presses (10, 20) can develop considerable pressing halls and reduce the thickness of the carpet by an additional 10% to 20% or the like. In a preferred embodiment of the finished board having a thickness of 10.2 mm (± 0.2 mm), the carpet has a thickness before entering the preform of about 70 mm, then about 20 mm after the exit of the preform and finally 10.2 mm at the exit of the calibration press. 20 May

During the passage through the main press and the calibration press, the process of hydrating the gypsum hemihydrate and solidifying it (gypsum dihydrate is formed) results in a structure in which the fibrous mixture of the surface layers 1, 3 is bonded to the mixture of the core layer 2 by the intergrowth of gypsum dihydrate crystals. Paper fibers are used to strengthen the board. Fibers of other materials may be used to affect the various grease of the board. By way of example, the use of polymer fibers can be used to improve the impact-absorbing properties of the finished sheet.

As can be seen in Figures 2 and 3, and as mentioned above, a known gypsum fiber board manufacturing plant is a device of the type shown in Figure 1 but does not contain the present invention and applies sequential pouring of mixtures the lower surface layers, the core and the upper surface layers, form a non-compact laminate carpet 2 having the form of the cross-sections shown in Figures 2 and 3 (c).

This non-compact carpet then advances to the pre-press station 8. The pressure applied at the pre-press station and the tendency of the top and bottom surfaces of the carpet to adhere to the belts 7, 9 with which these surfaces are in contact leads to further extrusion of the carpet sideways. d) and Fig. 3 (e)], wherein the core layer is also extruded in relation to the lower and / or upper surface of the carpet [see Fig. 3 (e)]. The presence of an aggregate-containing core layer material, such as perlite, on the surface of the board would significantly affect the strength of the board, and therefore it is necessary to trim the board edges 22 as shown in Fig. 3 (g) to form a necessary solid board having uniform structure in cross section of its width.

After the gypsum solidification is complete, the carpet is removed from the calibration press 20 and then trimmed to remove uneven portions of the slab to create a uniform structure that is dried after sweating.

By way of example of one embodiment of the present invention shown in Figs. 4 (a) to 4 (i), Figs. 5, 6 and 7, it can be shown that the vertical edge of the side strips 23 extends along the sides of the preforms and defines an extrusion barrier. carpets to the sides during its squeezing • in the pre-press station. The vertical edge of the side belts 23 moves at the same speed as the conveyor or forming belt 7 and the carpet 8.

In Figures 4 (a) to 4 (f) (which do not correspond to the same scale), it is shown that the presence of side barriers in the preform station significantly reduces or eliminates the amount of finished board material that has to be cut to produce an evenly structured board and hard edge. In addition, the advantage of reducing waste is that there is the possibility of producing wider plates in a production plant whose belts or press stations have a given width.

As can be seen in FIG. 6, the edge or side strips 23 are guided on rollers 24 which define a horizontal path 25 with a section 26 that extends parallel to the main forming belt 7 and provides a side barrier against extrusion of the carpet sideways in the preform or degassing. station. The preforming barriers of the present invention may be combined with barriers at other stages of the manufacturing process; for example in the molding phase, the main molding phase and / or the calibration molding phase.

In an alternative embodiment of the present invention [see Figures 8 (a) to 8 (d)], the side barrier is a hollow rubber hose 27 that contains pressurized fluid.

In a preferred embodiment, the hose has a canvas or textile sheath that resembles a fire hose sheath. The hose should be capable of being repeatedly compressed with little wear and should return to its original state after it is no longer compressed.

Useful fluids include compressed air or gas, oil or water. It is believed that it is particularly advantageous to use a hollow air hose 27 containing compressed air (something similar to an inner tube of an automobile tire), since such a hose allows considerable compression. A fire hose-like rubber hose 27 is routed on a horizontal track having a section that extends through a pre-press on the guide rollers 28 to extend through the pre-press or degassing station over the entire width of its Esu to provide a resiliently compressible barrier against extrusion densification in a preforming station.

Although the hollow hose illustrated in FIGS. 8 (a) to 8 (d) has a circular cross-sectional shape, other cross-sectional shapes (e.g., a triangle) that exhibit the ability to resiliently deform during their passage through the preform and outlet are also applicable.

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from this pre-press station. Applicants believe that a hose having a cross-sectional shape in which the vertical, flat side faces the carpet and the rounded side faces the guide rollers is particularly preferred. This flat side helps to keep the side edge of the compressed carpet straight and the rounded surface can more easily cooperate with guide rollers that could have concave surfaces for contacting the hose.

In a plant for the production of finished gypsum fiber boards having a thickness of approximately 10 mm and made of a non-compact carpet with a thickness of approximately 70 mm, it is recommended to use a barrier hose having a diameter of approximately 80 mm.

Giant. 9 shows an alternative barrier structure comprising two continuous strips 30, 31 having a series of elastic foam strips forming two successive block strips 30, 31. The lower foam block 30 of greater thickness moves along a path that resembles a path that was 6, and the upper, thinner block moves along a vertical path 32 defined by the rollers and having a section passing through the preforming station parallel to and above the section path of the strip of greater thickness (see FIG. 13, wherein the side barriers perform their function in the molding stage and in the pre-pressing stage).

The individual foam strips have cooperating and adjacent oblique fronts 39, 35, and 30. 33, which can slide relative to each other in the transverse direction as indicated in Figs. 10 (a) to 10 (c) in order to enter the preform. These foam blocks having a height of 40 mm slightly overlapped [see Fig. 10 (a)] and together defined a continuous barrier having a height of approximately 70 mm. (Height of entrance to preforming station). As they pass through the preforming station, the blocks move relative to each other and gradually overlap. With complete overlapping (see Fig. 10 (b) J), these blocks are compressed by the operation of the pre-extractor belts during further relocation within the preform 8.

The barrier blocks can be made of polyurethane foam having a density ranging from 50 kg-m ³ to 400 kg-m ³ . A preferred range is from 200 kg / m ³ to 300 kg / m ³ , 300 kg / m ³ being considered to be optimal.

The advantage of this system is that it allows the use of materials that are strong enough to act as effective lateral restraints but are not elastic enough to be compressed successively within 70% during passage through the preform and return to their original size after leaving this preforming station. The system shown in FIGS. 9 and 15 provides the ability to overcome the problems associated with the requirements placed on

-114 4 · 4 ····· 4 • · 4 · ·· ····································································· % without reducing or losing this elasticity.

In an alternative embodiment (see Figs. 11 and 12), the side barrier forms a single foam web 60. The foam web has an inclined face when uncompressed, but this face is in a vertical position during compression to assist in making a carpet with straight, vertical edges. .

Giant. 14 shows an alternative set of foam block profiles 40, 41 that can be used in a similar manner to the blocks shown in FIGS. 9 and 10. The lower foam sheet 40 has a rectangular cross-sectional shape with a height of approximately 35 mm and can be slidable in the upper channel. a foam strip 41 having a height of approximately 40 mm.

In an alternative embodiment (see Fig. 13), the double foam strips are replaced by a single foam stripe 50 which is guided in a manner similar to the edge strips shown in Figs. 5 and 6. The foam 50 has the shape of an inverted " V " "So as to be able to necessarily change its shape when compressed and returned to its original shape to the extent required by 70%, which is necessary for repeated passage through the preforming station 8.

The foregoing provides a description of several different embodiments of the present invention. Features included in one or more of the disclosed embodiments may be used in other embodiments either alone or in combination with other features.

Claims (27)

PATENT CLAIMS An apparatus for making a building board from a solidifying binder material, comprising a conveyor for moving material through a plurality of work stations, including a forming station for applying said solidifying binder material to said conveyor for forming a carpet, a degassing station for compressing said carpet to expel air, said degassing station comprising a barrier that prevents said carpet from being perpendicular to the direction of compression of said carpet during its compression, and a pressing station to apply pressure to said carpet during solidification of the binder material . The building board manufacturing apparatus according to claim 1, characterized in that the conveyor and the barrier are moving at the same speed. The building board manufacturing apparatus of claim 1 or 2, further comprising a mixing station for mixing said solidifying binder material with the fibrous material before said solidifying binder material is applied to said conveyor. 4. The building board manufacturing apparatus of claim 3, wherein said solidifying binder material is dry calcined gypsum, and wherein the solidifying binder material is blended with moistened paper fibers. The building board manufacturing apparatus of any one of claims 1 to 4, wherein the height of the carpet after processing in said degassing station is less than 50% of the height of the carpet prior to processing in said degassing station. 6. The building board manufacturing apparatus of claim 5, wherein the height of the carpet after processing in said degassing station has a value in the range of 25% to 35% of the height of the carpet prior to processing in said degassing station. 7. The building board manufacturing apparatus of claim 5, wherein the height of the carpet after processing in said degassing station is about 30% of the height of the carpet prior to processing in said degassing station. A building board manufacturing device according to any one of claims 1 to 7, characterized in that said barrier is resiliently compressible. 9. The building board manufacturing apparatus of claim 8, wherein said barrier is a hollow, resiliently compressible hose. 10. The building board manufacturing apparatus of claim 9, wherein said hose has a generally circular cross-sectional shape. 11. The building board manufacturing apparatus of claim 9, wherein said hose has a generally triangular cross-sectional shape. 12. The building board manufacturing apparatus of claim 9 or 11, wherein said hose has a generally flat, vertical face which prevents lateral ejection of the carpet during its compression. 13. A building board manufacturing device according to claim 9 or 12, depending on claim 12, wherein said hose has a generally convex, vertical face which cooperates with guide rollers having correspondingly generally concave surfaces. A building board manufacturing device according to any one of the preceding claims 1 to 8, characterized in that said barrier is formed by separate, adjacent, resilient blocks which move relative to each other. 15. The building board manufacturing apparatus of claim 14, wherein said adjacent blocks have adjacent inclined faces. W W 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 ·· ·· · · · · 16. The building board manufacturing apparatus of claim 14, wherein said barrier comprises two blocks, wherein the shaping of the first block resembles a trough and the second block has a profile that corresponds to the interior of a trough of said first trough. 17. A building board manufacturing device according to any of the preceding claims 14 to 16, wherein said barrier comprises two blocks, each block having a different stiffness. A building board manufacturing device according to any one of the preceding claims 14 to 17, wherein said barrier comprises an upper and a lower block, one of the blocks being part of a continuous belt moving along a track in a generally horizontal plane and the other. the block is part of a continuous belt that moves along a track in a generally vertical plane, the two tracks extending generally parallel to each other in the degassing station. 19. A building board manufacturing apparatus, characterized in that its overall description is made with reference to one or more of FIGS. 2 to 15. 20. A method of making a building board from a solidifying binder material, comprising the steps of forming the solidifying binder material into a carpet, compressing said carpet vertically to eject air from the carpet while preventing the carpet from being pushed horizontally transversely into the carpet. 3, pressing said carpet during solidification of the binder material. 21. A method of manufacturing a building slab according to claim 20, comprising the step of mixing said solidifying, binder material with the fibrous material prior to forming said carpet. 22. A method of manufacturing a building board according to claim 21 wherein said solidifying binder material is dry calcined gypsum, and wherein the solidifying binder material is mixed with moistened paper fibers. A method of manufacturing a building slab according to any one of the preceding claims 20 to 22, wherein the height of the carpet after processing in said degassing station has a value of less than 50% of the height of the carpet prior to compression. 24. The method of manufacturing a building slab according to claim 23, wherein the height of the carpet after processing in said degassing station has a value in the range of 25% to 35% of the height of the carpet prior to compression. 25. The method of manufacturing a building slab according to claim 23, wherein the height of the carpet after processing in said degassing station is about 30% of the height of the carpet prior to compression. 26. A method of manufacturing a building board according to any one of the preceding claims 20 to 25, comprising the step of forming a resiliently compressible barrier that prevents said horizontal ejection of said carpet in the transverse direction. 27. A method of manufacturing a building board, wherein the overall description thereof is performed with reference to one or more of FIGS. 2 to 15.