NO311709B1 - Process and apparatus for the manufacture of structures, special plates, and the use of such a plate / disc product - Google Patents

Abstract

The invention relates to a method and an apparatus for manufacturing cement flake boards (7) having hollow channels (10) arranged between outer board portions (8). A mix (11) comprising a fibre material and a cement binding agent is provided between outer press panel elements (5, 6), subjected to an outer pressure and rapidly cured under the influence of carbon dioxide gas. At least one separate core press expander element (3) is arranged between said outer press panel elements (5, 6), and prior to the curing said mix (11) is subjected to an inner pressure by expanding said core press expander element(s) (3) inside said mix (11) between said outer press panel elements (5, 6).

Description

The invention relates to a method for the production of structures, in particular for the production of plates which have at least one, preferably several, adjacent hollow channels arranged between outer plate parts, which method is also otherwise of the type specified in the introductory part of patent claim 1.

The invention further relates to an apparatus for the production of cement chipboards or the like of hollow joist type, which apparatus is of the type specified in the introductory part of patent claim 9.

Finally, the invention relates to a use of a plate/disc product which is produced in accordance with the above-mentioned method, which use is indicated in patent claim 8.

Prior art defines many methods for producing plate-like structures of concrete or similar stabilizing material. Such structures are used particularly within the construction industry for buildings erected on site. Typically, such methods include pouring wet concrete into a desired shape, compacting the cement using a vibrating agent to lower the concrete's internal friction, and curing the concrete simply by using sufficient time, alternatively by adding certain curing additives or by increasing the temperature. The resulting product will usually have opposite planar surfaces. In some cases, the product will also include hollow parts to make the product lighter or to save some concrete. In a hollow-core plate, many adjacent hollow parts extend through the entire plate. In some cases, such hollow parts are filled with insulating material and/or used as conduits for piping or the like.

The purpose of the present invention is to achieve such a product in a way whereby the product can be produced by a very fast process whereby the resulting structure nevertheless has all the necessary properties which are needed particularly when erecting buildings, such as detached houses or the like, preferably in a module size. A particular object of the invention is a complete building system comprising hollow elements of the module type, which are made of a cement-wood chip mixture which can preferably be produced from easily available materials in most countries. The system involves the use of hollow plate-type elements preferably having a full wall height of about 2.4 meters in arbitrary lengths up to about 10 to 15 meters. The thickness of such an element is preferably approximately 200 mm, and the element itself is of a hollow frame type which has composite plates, which form generally uniform outer/inner surface parts which are connected by relatively thin transverse intermediate rods. In order to meet any building-related requirements, it should be possible to pre-determine the exact position and extent of the hollow channels, so that the wall thickness and the location of the connecting crossbars can be pre-arranged at any time in accordance with the results of the building-related calculations that may be required be necessary. The arrangement should also be such that the position of the neutral axes of the respective mixture parts, which mixture parts make up the main parts of the structure, can remain mainly in their original positions, which feature is particularly important when a fast-hardening mixture is used.

According to the system of the invention, an entire building, including floor, internal roof and external roof, consists of a single type of hollow plate element. Said elements are joined only along their sides, which makes the installation process very simple. All openings in the elements, e.g. for doors and windows, etc., can be cut on site. In a similar way, any special structural details can be produced by cutting away parts from hollow plate elements according to the invention, which elements are of standard size.

The invention makes use of a process which uses a mixture of wood shavings, e.g. from timber waste or the like, and cement, which mixture is shaped and hardened in a special type of press. For the hardening of the mixture, the system according to the invention uses a special process which is described in more detail, e.g. in EP patent 189 127, which process uses carbon dioxide to increase the curing rate of the mixture. Said EP patent, the full content of which is incorporated herein by reference, also indicates how special advantages can be obtained by compressing a mixture of fiber material and cement in connection with the injection of carbon dioxide.

Injection of excess carbon dioxide gas into such a material facilitates a rapid carbonization of part of the cement binder, mainly through the process CaO + C02 => CaC03. Such processes have previously been described, e.g. in US patent

109 669, 3 462 993, 4 362 679, 4 093 690, SE patent 110 792, GB patent 1 460 284 and CH patent 584 666. According to the aforementioned documents, the process must take place in completely closed process chambers, which is considered be a serious disadvantage on an industrial production scale.

The special process shown includes a method for curing cement-jointed panels and elements of fiber material, where the fiber material and the cement in a known composition and with water as an activator are carbonized with carbon dioxide gas. According to the process, such fiber material with its accompanying substances is placed between press plates in a press machine. Since the fiber material is slightly compressible, a large amount of carbon dioxide gas can be injected, after which the material is compressed to the final dimensions of the structure to be produced. Said European patent 189 127 describes how the use of a completely closed process chamber can be avoided by pressing the edges of the material to a higher density, which forms a gas barrier that replaces said completely closed chamber. The present invention uses some of the features in the aforementioned EP patent and achieves within a completely new concept many advantages that are completely unknown within prior art. The present invention utilizes the compression of a mixture of fiber material and binder to achieve a very high gas injection rate in the relatively loose mixture before compression. In the next step, the material is compressed to its final dimensions, and the rapid hardening or consolidation of the binder, e.g. cement or similar, takes place. In the process according to the present invention, the use of both completely closed process chambers, as described in the prior art, and particularly compressed parts, as described in the aforementioned EP patent, can be avoided.

The characterizing features of the present invention appear clearly from the appended claims.

The apparatus according to the invention is thus characterized in that said apparatus comprises special core press expander elements which are to be placed in said mixture or mortar between said outer press panel elements for the design of internal channels in said plate which is produced between said outer press panel elements. The method according to the invention is characterized in that said core press expander elements are arranged between said outer press panel elements and exposes, before the hardening of said cement-based binder, said mixture which is placed between said outer press panel elements, to an internal additional pressure by expanding said core press expander elements essentially uniformly inside said mixture between said outer press panel elements. In at least one direction, said core press members' expansion rate generally corresponds to said outer press panels' press rate, in which case the neutral axes may remain substantially in their original positions.

The core press expander elements according to one embodiment of the invention comprise movable parts that cooperate with corresponding parts of adjacent core press expander elements or with said outer press panel elements. In an expanded position, said core press expander elements compress between themselves the intermediate parts of said mixture in a uniform manner, while mainly maintaining said intermediate parts' neutral axes in their original positions in relation to the respective core press expander element's longitudinal axis. Said core press expander elements further comprise means for maintaining a controlled migration of carbon dioxide and/or air within said mixture. In order to achieve full control of the pressing process, said core press expanders usually comprise many rigid elements arranged in a special way according to the idea of the invention, so that said core press means are able to expand in an essentially uniform manner without any local deformations due to uneven internal pressure or uneven load distribution in the joint area between the expander and the raw mix material that makes up the element walls and crossbars.

According to the invention, an excellent hollow cement board is formed, as a result of the above-mentioned raw material, in a single or multi-stage pressing operation, including hardening of the raw material mixture or mortar. Actually, the apparatus according to the invention is a press form composed of two presses, one of which is a horizontal flat press consisting of upper and lower press plates which are movable within enclosing edges. According to the invention, the press mold according to the invention further comprises separate expanding core presses placed between said horizontal press plates.

A typical panel product would comprise an approximately 200 mm thick panel member having two approximately 20 mm thick panels joined by cross bars of equal thickness at approximately 400 mm center distances. All these elements, i.e. said panels and said connecting crossbars are formed in a single operation by simultaneously applying internal and external pressure to the mixture through a very short curing or consolidation process. Each respective connecting crossbar's normal axis will thus be maintained mainly in its original position throughout the curing process. Any unfavorable stresses and strains in the final product will thus be reduced already during the curing period. During the curing process, carbon dioxide gas under pressure is injected into the mortar, e.g. a wood sponge-cement-water mixture hereafter called the CFB mixture. Due to the use of excess carbon dioxide, the entire curing process only takes about 4-5 minutes, whereas a normal cement consolidation process initially takes 8 to 10 hours. The entire manufacturing cycle for one plate element can thus be completed in approximately 10 minutes.

Cement chipboard (CFB) is very advantageous for the idea of the invention. The CFB element can also be used indoors

as outdoors, as it is weatherproof, waterproof and insensitive to frost. The CFB production process contributes to environmental protection by sequestering carbon dioxide in a non-polluting product. CFB is fairly fire-resistant and has relatively good acoustic properties, since it contains a large degree of sound insulation.

The production of full size hollow plate elements is the key operation in the system according to the invention, and this is used in the special press die arrangement according to the invention, which is explained in detail below. In this respect, it is also important to the process that carbon dioxide can be effectively distributed throughout the sheet material to facilitate the rapid hardening of the cement in accordance with the principles set out in the above-mentioned EP patent 189 127.

The method according to the present invention provides a hollow plate structure comprising a finished element with a double wall, which has crossbars placed at a distance between them, which connect said walls to each other. By pressing the mixed material from both external surfaces and at the same time also from the inside, a completely new design idea is achieved. The neutral axis, i.e. the functional center of gravity for each wall section of the mixed material, is thus kept essentially stationary from the unprocessed to the pressed stage.

The invention will now be explained in more detail with reference to the attached drawings which show some preferred embodiments of the invention. Fig. 1 shows a schematic perspective view of a building which has been erected by using hollow plates according to one embodiment of the invention; Fig. 2 shows a general exploded view of a mold arrangement according to one embodiment of the invention; Figs 3 and 3a show a schematic elevation of a section of a batch of two alternative arrangements of the compression molding apparatus, where the dashed sections indicate a CFB mixture before compaction, and the hatched sections indicate the CFB mixture in a compressed and hardened state; Fig. 4 shows a schematic sectional view of a double-acting press arrangement according to a particular embodiment of the invention; Fig. 5a and 5b show schematic views of the injection principle for carbon dioxide according to one embodiment of the invention; Fig. 6 shows a more detailed elevation of a partial cross-section through a wedge-type core press expander according to one embodiment of the invention; Fig. 7 shows a schematic sectional view through an expanded core press expander according to a particularly preferred embodiment of the invention, and Fig. 8 shows the core press expander in fig. 7 in a retracted state and still placed inside the hollow channel portion of a finished CFB board.

Reference is now made to fig. 1 where a building according to the invention mainly comprises a floor element A, wall elements B, B'

and external roof elements C. In said wall elements B, B' there are openings for doors D, windows E and the like. According to the idea of the invention, all of the mentioned basic building elements A to C comprise hollow plate elements produced in a press arrangement as indicated in fig. 2, said press arrangement generally comprises a horizontal lower press panel arrangement 1, a horizontal upper press panel arrangement 2 and intermediate core press elements 3 arranged horizontally between said lower and upper press panel arrangements 1, 2, the longitudinal axis of a core press element 3 being indicated as F-F. Said press panel arrangements preferably comprise wall sections 4, 4a, partly shown in fig. 2 and 4, and separated

horizontal lower and upper press panels 5, 6, at least one of which is movable towards the opposite one. Between the essentially rigid surface parts 5a, 6a of said lower and upper press panels 5, 6, one or more core press elements 3 are arranged. Said core press elements 3 can be expanded and comprise essentially rigid surface parts 3a which are arranged to exert a pressure on the inner parts of a CFB mixture or the like, which is provided between said press panel arrangements 1, 2. Since the relative movement of said lower and upper press elements 5, 6 is normally vertically directed, i.e. transversely in relation to the general horizontal extent of the element to be produced, the surface of the final element can be made in any desired shape, for example flat, corrugated or with a decorative pattern.

According to fig. 3 and 3a, each hollow plate element 7 comprises outer panel parts 8 which are connected through transverse rod parts 9. Since one of the favorable properties of CFB plates is that they can be processed relatively easily, the idea of the invention makes it possible to make all openings in the plate elements that make up the final building (see Fig. 1), such as said openings for doors D, windows E and the like, as well as any special structural details, e.g. details of non-rectangular shape or of small dimensions, in the CFB plate elements 7 after these have been produced in the press arrangement according to the invention. Said plates 7 can thus be produced as substantially identical plates, which makes production considerably easier.

According to the idea of the invention, said CFB plates are generally produced in standard sizes. A typical element plate 7 calculated for a detached house, as shown in fig. 1, has a total width of approximately 2.4 meters and a length of up to 10 to 15 meters. The thickness of the element plate is suitably approximately 200 mm. In section, as shown in fig. 3 and 3a, each complete element plate 7 comprises adjacent hollow channel parts 10 which extend through the entire extent of said element plate 7. Said hollow channel parts 10 are surrounded by said crossbar parts 9 and said panel parts 8. In fig. 3 and 3a, the neutral axis G-G, G'-G' of each part 8, 9 is shown by phantom drawing. Here fig. 3 a preferred embodiment where said neutral axes G-G, G'-G' remain essentially in their original absolute positions due to generally uniform compression, while fig. 3a shows part of a final product where a non-uniform compression has been used. In an element shown in fig. 3 and 3a, said crossbar and panel parts 8, 9 suitably have a thickness of approximately 20 mm, and the central distance between said crossbars 9 is suitably approximately 400 mm, but in other designs and areas of application different dimensions can of course be used within the scope of the invention.

According to fig. 3 and 3a is a CFB mixture 11 (shown in dotted section) provided between said outer press elements 5 and 6

(of which only sections are shown for the sake of clarity)

within said wall parts 4, 4a which preferably surround the unit (see fig. 2 and 4). Essentially centrally between said press elements 5 and 6, and thus surrounded by said CFB mixture 11, there are many adjacent core press elements 3 (one of which is shown in Fig. 2) arranged in a predetermined relationship with a fixed mutual distance. Before compression, the distance between the respective surfaces of adjacent core press elements 3 and between any core press element 3 and said outer press elements 5, 6 corresponds to the uncompressed extent of said CFB mixture 11. Typical for

a CFB plate of the above-mentioned dimensions, the free distance between each two of said press elements 3 and 5, 6 respectively, would be approximately 60 mm before the compression. In a completely compressed state, each pair of opposing surfaces of said press elements 3, 5 and 6 will have moved approximately 20 mm each, whereby they thus for each mixing portion 11 provide a total compression of approximately 65% appropriately distributed in all substantially equally to each pair of said outer and inner press elements 3, 5 and 6 respectively. In this connection, and particularly when referring to fig. 2, it can be seen that due to the fixed arrangement of the press elements 3, 5 and 6, the relative position of each press element's press surfaces at the final stage of the press movement and thus the position of the hollow channel portion 10 in the final product can be pre-determined very accurately. This is a very important feature when considering the accuracy of strength calculations.

According to the invention, the process includes the steps of pressing the uncured CFB mixture from a generally loose state, as indicated in dotted section in fig. 3, 3a, to a compressed state as indicated in hatched section in said figures. Generally, the total compression would be in the range of 30 to 80%, usually 50 to 75%, depending on the mixture used. In the favorable embodiment shown in the figures, the applied pressure would thus compress the mixture from 60 to 20 millimeters. In the crossbar section 9 between each two of said core press expander elements 3, the total compression would usually be distributed with an equal amount to each expander element 3. In the panel parts 8, the internal distribution of the total compression is between the press surface of each outer press element 5, 6 and the corresponding opposite surface of the core press expander element 3 selected, taking into account the technical features of the respective presses, the mixture used, as well as the desired position of the neutral axis. In all cases, the core press expander element 3 is expanded at least a few millimeters to facilitate its removal. In practice, the proportion of the compression effected by the internal core press expander element 3 can vary within the idea of the invention in a range from about 5% to about 80% of the total compression, usually at least 25%, and in a preferred embodiment about 50%, i.e. when both surfaces move essentially the same towards said mixture 11. The compressed state generally corresponds to the final extents of the produced CFB plate 7. The compression is carried out just before the hardening of the cement binder in the CFB mixture and will in most cases correspond to a pressure in the range of 15 to 50 bar.

According to a preferred embodiment, the compression process comprises two steps which are carried out within a few seconds. In a first step, the adjacent core press elements 3 are expanded to give the hollow channel portion 10 inside the plate 7 its correct dimensions. At the same time, they compress the CFB compound to give it the special favorable features indicated in the aforementioned EP patent 189 127. Typically, the expansion for an element having the general dimensions indicated above would be about 20 mm to each crossbar side and about 3 mm to each panel page. The expanded core press element 3 and the resulting hollow channel section 10 are thus at least in two dimensions slightly larger than the aforementioned core press element 3 in its retracted state, and the removal of the core press elements 3 from the hollow channel sections 10 of the final plates 7 will thus be easy. This fact appears more clearly from fig. 8. Since the expansion of all core press elements 3 is carried out simultaneously, the respective neutral axes G'-G' at each crossbar portion 9 will remain substantially in their original location, i.e. there will be very little internal movement in the CFB mixture.

In a subsequent pressing operation which will take place in immediate connection with the first one described above, the three press panel elements 5, 6 are pressed against each other to press the panel surface parts of said CFB mixture 11. This pressing takes place on both sides of said core press elements 3 and can be performed by pressing both outer press elements 5, 6 against each other and against stationary core press elements 3. In a preferred embodiment, said core press elements 3 can be moved in the pressing direction of one outer press element, so that only one, usually the upper 6 of said outer press elements, will move towards a stationary lower outer press element 5. In this case, the entire unit of core press element 3 will simultaneously move approximately half of the movement of the upper press element 6.

In a preferred embodiment, the mold arrangement comprises a separate matrix element (not shown) which comprises at least a bottom plate as well as positioning means to hold said core press elements 3 in place. In certain embodiments, said positioning means further comprises means to move said press elements vertically to achieve the movement discussed above. The matrix element can preferably further comprise side wall sections which surround said matrix bottom plate. In use, said matrix is filled with CFB mixture, and the filled unit is then fed between said outer press elements 5, 6 which can be essentially stationary and arranged only for the actual press movement on said matrix element's upper and/or lower sides.

In a particularly preferred embodiment shown in fig. 4, a single, movable, central "outer" press element 6' is arranged between two essentially stationary outer press elements 5', 5". In this embodiment, two plates 7 can be produced halfway at the same time, i.e. one plate is pressed and hardened while the second, already finished plate is taken out and raw CFB mixture is placed in place of this plate, thus increasing the capacity of the apparatus considerably.

Due to the special method of curing the cementitious binder in said CFB mixture in about 5 minutes, the complete process cycle comprising filling the CFB mixture, pressing the mixture and curing the binder therein will take only about 10 minutes. For this reason, a preferred arrangement of the carbon dioxide injection system is of the greatest importance for the arrangement according to the invention.

According to the invention, the core press elements represent 3

which extends in the center of the CFB mixture 11, a favorable channel for injecting carbon dioxide gas into the CFB mixture. Said core press elements 3 thus comprise, in accordance with a preferred embodiment of the invention, connected

carbon dioxide gas channels 13 as well as a suitable perforation in the outer surfaces (not shown separately) which allows said gas to flow out into the CFB mixture surrounding said core press elements 3.

In a preferred embodiment shown in fig. 5a and 5b, the injection of carbon dioxide gas into the CFB mixture is arranged as a two-stage operation, the principle of which is known per se from the above-mentioned EP patent 189 127. In a first stage (see fig. 5a) a gas mixture is of carbon dioxide and air pumped via said outer press elements into said CFB mixture, as indicated by arrows 14 towards said mixture. This creates an overpressure of carbon dioxide in said CFB mixture. In this connection, a vacuum or reduced pressure is maintained in said core press elements 3, as indicated in fig. 5a with arrows 15 directed towards the center of said core press element 3. This vacuum facilitates the passage of said gas mixture through said CFB mixture and increases the amount of carbon dioxide that comes into contact with the cement binder, particularly in the mixture that makes up the outer panel parts of the final CFB plate.

In a second step, as shown in fig. 5b, each of said core press elements 3 is also pressurized with said gas mixture, which excess pressure is indicated by arrow 16. This second step facilitates a corresponding passage of said gas through the intermediate wall sections 9 which are placed between the hollow channel sections in the final CFB sheet, and thus practically all free air that hinders the curing process can be replaced by a specially composed carbon dioxide mixture that significantly reduces the curing time.

For most cases, however, it has proven to be

sufficient to carry out the introduction of carbon dioxide in a single step by blowing said gas directly into said core press elements 3. In fact, this method is preferred, as maintaining a gas flow in only one direction, i.e. into said core press elements 3, will keep them and especially

the gas channels 13, which will be discussed later, free from impurities of any kind.

The core press elements 3 form an extremely central part of the invention. Fig. 6 shows a core press element 3 according to one embodiment of the invention. Fig. 6 shows a partial section of such an element 3 in a direction across the longitudinal axis F-F of said element. In general, the core press elements 3 are oblong elements having wall portions which are movable in directions perpendicular to said longitudinal axis F-F. Said elements 3 are thus expandable in both their lateral directions and can exert a compressive force against the surrounding CFB mixture which will be compressed between adjacent core press elements 3 and/or between such an element 3 and one of said outer press elements 5, 6.

In the core press element 3 according to fig. 6, the molding press surfaces preferably comprise substantially flat or at least generally smooth surface elements 17 and special corner elements 18. In fig. 6, said corner elements 18 are shown in an extended position, from which said elements 18 can be retracted to a position where they allow edges 19 of adjacent, substantially flat, rigid surface elements 17 to maintain a mutual contact. Said corner elements 18 have a wedge surface 21 which interacts with a corresponding internal wedge-cut surface 20 on said planar surface elements 17. At each corner, said core press element can thus

3 dimensions are expanded and retracted an extent corresponding to the width (indicated by "a" and "b") of said corner elements 18's corner portions by moving said corner elements 18 in relation to said planar side surface elements 17. The necessary movement is achieved e.g. through hydraulic or similar means or preferably, as indicated in fig. 6, through cooperating wedge means 22, 23. Fig. 6 also shows that gas channels 13 are arranged inside said core press element 3 and lead through said planar side surface elements 17 for contact with a CFB mixture 11 which is provided outside said core press elements 3. Preferably, said wedging means successive wedges 22 which are attached to said planar side surface elements 17, as well as successive wedges 23 attached to a central activator rod 24 which suitably extends through the entire extent of said core press element 3. By moving said actuator rod 24 in the direction of the longitudinal axis F-F of said element 3, all wedges 23 will move and at the same time push the respective wedges 22 outwards, which movement will cause a uniform lateral movement of said planar side surface elements 17 and said corner elements 18. Thus, said core press element's 3 dimensions can be changed between a completely retracted position which has substantially closed corners between said planar side surface elements 17, and a fully expanded position, where said corner elements 18 will fill in the corner portions between said planar side surface elements 17. In both positions, the core press element will 3 constitute a closed shape structure which has essentially sharp corners. Said corners can also be easily rounded a little, which will give somewhat rounded internal corners 25 in said plates 7 hollow channel parts 10, as indicated in fig. 3a. In some embodiments, the outer surfaces of said surface elements 17 can actually also be rounded, which in some special cases can produce an almost oval cross-sectional shape. Fig. 7 and 8 show a particularly preferred core press element 3 according to an alternative embodiment of the invention. In this embodiment, the most important molding and pressing surfaces comprise generally L-shaped wall sections 26 and wedge means 27, 28 to move said generally L-shaped wall sections 26. For the sake of clarity, said L-shaped wall sections are shown here as strictly right-angled pieces, but their actual cross-sectional shape may of course be subject to quite free changes in accordance with the desired cross-sectional shape of the hollow channel. Fig. 7 shows said core press element 3 in an expanded position and Fig. 8 the same element 3 in a retracted position inside the hollow channel portion 10 of a plate 7. In both figures, the right part is a section through activation or expander means 29 which exerts a thrust on said wedge means 27 to press one end of opposite pairs of said L-shaped wall sections 26 outward laterally. At the same time, guide wedges 28 interact with inclined counter surfaces 30 arranged at a central bar 31 and drive the remaining free ends 32 of said L-shaped wall sections 26 outwards. Thus, a pressure can be exerted on a CFB mixture 11 outside the core press element 3. The left part of said fig. 7 and 8 show a section through retraction means 33 for retraction of said L-shaped wall portions 26 after the completion of the forming operation and before the removal of said core press element 3 from the hollow channel portion 10 of the final plate 7, a section of which is shown in fig. 8. As indicated, there will be a space 12 between the inner wall of said hollow channel portion 10 and the retracted core press element 3, which will facilitate the removal of said element 3 from said plate 7.

Generally, expanding means 29 and retraction means 33 are arranged successively, so that between every two expanding means 29 there is a retraction means 33. In the embodiment according to fig. 7 and 8, the expander means 29 comprises a preferably hydraulic piston 34 which moves in a cylinder means and has bolts 35 which press against a common pressure plate 36 which holds said wedge means 27, which in this case are pressure cones or the like which extend into the wedge-shaped space between two adjacent of said L-shaped wall parts 26. Said pressure plate 36 drives said wedging means 27 between said L-shaped wall parts 26 and thus forces them to move apart at said wedge-shaped space. When said pressure plate 36 reaches the inner front surfaces of said L-shaped wall parts 26, said pressure plate 36's movement will further drive said L-shaped wall parts 26 to move forward, and then said guide wedges 28 will move along said inclined counter surface 30 and also force said free ends 32, i.e. the middle part of said core press element 3 one side, outwards towards said CFB mixture 11.

The retraction means 33, on the other hand, suitably comprise spring means 37, 38 which act against the force from said expander means 29, and pull said pressure plate 36 inwards when said expander means 29 are out of action. Said pressure plate is suitably movable towards an inner threshold 39 arranged at each of said L-shaped wall parts 26, and said pressure plate 36's inward movement will force said L-shaped wall parts 26 away from the inner surface of said CFB plate 7 hollow channel section 10 and produce said space 12, the extent of which corresponds to the compression of said CFB mixture 11.

In order to maintain a smooth inner surface of said hollow channel part 10 in the final plate 7, said L-shaped wall parts are preferably at least partially covered by one or more layers of substantially rigid cover plates 40, 40', which preferably in the the smallest in a central area 41 at said free ends 32 of said L-shaped wall sections 26 comprises tongue elements in engagement between adjacent cover plates 40, 40'. This central area 41 is preferably supported by a separate support plate 42. In the embodiment shown in fig. 7, the short ends of said L-shaped wall parts 26 do not need any tongue devices in engagement, since said cone or wedge means 27 suitably extends between cover plates 43, 43' at said ends and fills the space between them. In another embodiment, the arrangement at said short end is similar to the arrangement at the long ends and includes corresponding engaging tongue arrangements. In this case, said wedging means 27 can also be located at said pressure plate 36's outer parts, preferably as an integral part thereof. A preferred embodiment thus comprises pressure plates 36 which have wedge-shaped sides which cooperate with wedges placed at the respective internal corners of said L-shaped wall sections 26.

As in the embodiment shown in fig. 6 comprises the embodiment according to fig. 7 and 8 also channels 13 for carbon dioxide gas or the like to be injected into said CFB mixture. Said channels 13, some of which are shown in the figures, are supplemented with a suitable perforation in said cover plates 40, 40', 43 and 43'. The gas mixture used for the hardening of the cement binder can thus freely move from the inner parts of said central rod 31 through the entire core press element 3 to the CFB mixture 11 outside. In certain embodiments, said channels 13 and said supplementary perforations are also used for the extraction of air, as is discussed in more detail in connection with fig. 5a and 5b.

Above, some of the preferred embodiments of the invention have been described. However, the description should only be regarded as an example, and it is clear to an expert that the invention can be changed in many other ways within the scope of the appended claims. All or some of the above-mentioned hydraulic means can thus in one embodiment be replaced by means activated by the pressure from said carbon dioxide gas. Furthermore, the core press element 3 may comprise other types of press elements such as a tube-like press element which has an expandable inner bag-like means to be filled with fluid under pressure, as well as outer surface means which have telescopic properties in directions across the longitudinal axis of said element 3. The idea of the invention can also be used for the production of different types of structures, i.e. for gutter elements or similar tubular structures.

Claims (19)

1. Method for the production of structures, in particular for the production of plates (7) which have at least one preferably several adjacent hollow channels (10) arranged between outer plate parts (8), said method comprising providing a mixture (11) which mainly comprising a fiber material, a cement-based binder and an activator liquid between outer press panel elements (5, 6), and movement of at least one of said outer press panel elements (5, 6) towards said mixture (11) to expose said mixture (11) for an external compression, as well as rapid carbon dioxide hardening of said cement-based binder by exposing said mixture (11) to the action of carbon dioxide gas, and where you subject the mixture (11) also to an internal pressure by means of at least one core pressing element (3 ) which is arranged between the outer press panel elements (5, 6), characterized in that, before hardening the cement-based binder in the mixture (11) which is g between said outer press panel elements (5, 6), at least in one direction also exposes the mixture (11) from the inside to such a significant compression that roughly corresponds to the compression directed from the outside towards the mixture (11), through expanding said core press expander element ( ) (3) in said mixture (11) between said outer press panel elements (5, 6) to press essentially rigid surface parts (3a, 17, 40) at the core press expander element(s) (3) against the opposing outer movable press panel elements ( 5, 6) and against possibly adjacent corresponding core press expander elements (3). 2. Method according to claim 1, characterized in that the total compression of said mixture (11) in at least one direction is 30% to 80%, in particular 50% to 75%, and most suitably approximately 65%, the internal distribution of said total compression between the surface of said core press expander element (3) and the opposing press surface of each corresponding outer press element (5, 6) and/or an adjacent core press expander element (3) is in the range of 5% to 80%, preferably about 50%. 3. Method according to claim 1 or 2, characterized by expansion of at least two adjacent core press expander elements (3), placed with a distance between them inside said mixture (11), in such a way that the neutral axes (G'-G') in said mixture (11) which is placed between each two of said adjacent core press expander elements (3), will remain essentially in its original position in relation to the respective core press expander element's (3) longitudinal axis (F-F). 4. Method according to claim 3, characterized by subsequent activation of at least one of said outer press panel elements (5, 6) and pressing of said mixture (11), preferably so that the neutral axis (G-G) in said mixture (11) placed between said core press elements (3) and preferably the lower (5) of said outer press panel elements (5, 6) remains essentially in its original position. 5. Method according to any one of claims 1 to 4, characterized in that said method further comprises injecting carbon dioxide gas through said core press expander elements (3) which are arranged for internal pressing. 6. Method according to claim 5, characterized in that said method further comprises that before the carbon dioxide injection, a partial vacuum is created within the frame for core press expander elements (3) which are arranged for internal pressing. 7. Method according to claim 5 or 6, characterized in that carbon dioxide and/or the partial vacuum is assigned alternating pressure within the frame for two adjacent core press expander elements (3) which are arranged for internal pressing. 8. Use of a sheet/disc product (7) produced in accordance with a method according to claims 1 to 7 as a building element for erecting complete buildings or the like, and that the elements form entire building parts (A, B, B', C ), from which, if necessary, openings (D, E) are cut for doors, windows and the like. 9. An apparatus for the production of cement chipboards (7) or the like of hollow joist type, said apparatus comprising outer press panel elements (5, 6) which can be operated in an appropriate manner so that they press together a mixture (11) mainly comprising a fiber material, a cement-based binder and an activator liquid, which mixture (11) in the hardened state defines said plate (7); which apparatus further comprises at least one core press expander element (3) for internal pressing and intended to be placed in said mixture between said outer press panel elements (5, 6) in order to form, in the disk/plate (7) to be produced, at least an inner channel (10) between said outer press panel elements (5, 6), with the core press expander element (3) further connecting carbon dioxide injection means (13) for injecting carbon dioxide into said mixture (11) and maintaining a controlled migration of carbon dioxide and/or air to carry out a rapid hardening of said cement binder, characterized in that core press expander element (s) (3) which is arranged for internal pressing, comprises movable parts (17, 21, 26, 27, 40) of largely rigid construction which cooperates with corresponding parts of adjacent core press expander elements (3) for internal pressing and/or with said outer press panel elements (5, 6), as these movable parts (17, 21, 26, 27, 40) in an expanded position is arranged to expose the mixture (11) from the inside between the substantially rigid parts (3a, 5a, 6a, 17, 40) of said elements (3, 5, 6) ) for such a significant compression which essentially corresponds to the compression that the aforementioned press elements) (5, 6) direct from the outside against the mass (11). 10. Apparatus according to claim 9, characterized in that each of said core press expander elements (3) which are arranged for internal pressing is an element which extends in the longitudinal direction and in the longitudinal direction preferably has four movable press wall part elements (17, 26) which in a cross section of said core press expander element's (3) longitudinal extent defines a rectangle which in said core press expander element's (3) expanded position extends to the position of the final internal surfaces of said internal hollow channel(s) (10), said core press expander element(s) (3) further comprises elements, preferably wedge means (21, 22, 23, 21, 28), to press said wall elements (17, 26) to said expanded position inside said mixture (11), preferably while the neutral axes (G-G, G' -G') in said intermediate parts of said mixture (11) remain in their original positions in relation to the longitudinal axis (F-F) of the respective core press expander element ent (3) arranged for internal pressing. 11. Apparatus according to claim 10, characterized in that at least some of said wedging means (21, 27) are adapted to fill spaces formed between said wall elements (17, 26) and to, in an expanded form at said core press expander element (3) which is arranged for internal pressing, to form part of the mold surface which defines said channels (10) in said plate (7). 12. Apparatus according to any one of claims 9 to 11, characterized in that within the frame of the core press expander elements (3) arranged for internal pressing, central wedge carriers are arranged which comprise beams (24, 31, 36) which support the wedges and optionally furthermore wedge sliding surfaces (23, 30) to cause said wedge portions (22, 28) to force said wall portions (17, 26) outward from a central longitudinal axis of core press expander element (3) arranged for internal pressing, along a precisely defined path, and further preferably comprises activator means (29), preferably hydraulic or pneumatic cylinders (34) or the like to move said wedge support beams (24, 36) which support the wedges (24, 36) and to initiate the expansion of said core press expander element(s) (3 ) which is arranged for internal pressing. 13. Apparatus according to claim 11 or 12, characterized in that said movable press wall parts are generally flat elements (17), and that said wedging means (21) in the expanded position of said core press expander elements (3) which are arranged for internal pressing, extend into in the open corners between the edges (19) of the movable wall parts (17) which lie next to each other. 14. Apparatus according to claim 11 or 12, characterized in that said movable press wall parts in cross-section are generally L-shaped wall parts (26) which each cover a corner of said channel (10), the wedge means (27) being adapted to press said L -shaped wall parts (26) towards the respective corners of said channel (10), and that means (40, 40', 41) are arranged to cover the longitudinal openings which are formed by the expansion of said core press expander element(s) (3) the flat surfaces between adjacent L-shaped wall sections (26). 15. Apparatus according to claim 14, characterized in that at least some of said means for covering said longitudinal openings are separate sliding overlapping covering means (40, 40') arranged inside and/or between and/or outside said L- shaped wall sections (26). 16. Apparatus according to claim 14, characterized in that at least some of said wedging means (18, 27) simultaneously act as said means covering said longitudinal openings. 17. Apparatus according to claim 14, characterized in that said central means (24, 31) which supports the wedges, further comprises means (33) which is specially arranged for, from the wall rafts at said channels (10) in said disks (7), to pull back the wall parts (16, 26) of the core press expander elements (3) arranged for internal pressing. 18. Apparatus according to any one of claims 9 to 17, characterized in that said means for maintaining a controlled migration of carbon dioxide comprise connection channels (13) formed in the inner parts of the core press expander elements (3) arranged for internal pressing, as well as perforated parts arranged at the outermost surfaces (40, 40', 41 43, 43') of these core press expander elements (3) arranged for internal pressing and as connected to said connection channels (13). 19. Apparatus according to any one of claims 9 to 18, characterized in that said outer press panel elements (5, 6) comprise two fixed press elements (5', 5") and a movable intermediate press element (6<1>) arranged between them, and that the apparatus further comprises means for driving said intermediate pressing element (6') towards a respective element of said fixed pressing elements (5', 5") in an alternating movement, and that additional means are arranged to move a respective layer of inner pressing arranged core press expander elements (3) between this movable intermediate press element (6') and respective fixed press elements (5', 5") over an extent that corresponds to generally half the extent of said intermediate press element's (6') movement.