FI101054B - Method and apparatus for making hollow core plates - Google Patents

Abstract

The invention relates to a method for manufacturing structures having at least one hollow longitudinal channel arranged between outer board portions. Compressible and curable matrix material (4) is arranged between outer press panels (1, 2, 3) and separate core press expander means (6, 6a) are arranged in said material (4). Pressure is applied to said material by said core press expanders and said press panels (1, 2, 3). Said curable matrix material (4) contains a heat curable glue agent and said method further comprising the providing of a heat impact to said glue agent. The invention also relates to an apparatus for the manufacturing of a board or the like. Said apparatus comprises an arrangement of outer press panels (1, 2, 3) as well as channel core press expander means (6, 6a) located therebetween, for compressing said matrix material (4) to the final dimensions of said board (5). Means are arranged for transporting a pressurized hot fluid through channels, for contacting with said matrix material (4).

Description

101054

Method and apparatus for making hollow core slabs Förfarande and anordning för tillverkning av hälkanalplattor

The invention relates to a method for manufacturing structures, in particular plates, in which the structures have at least one, preferably several adjacent longitudinal channels arranged between the outer plate portions. Said method comprises the steps of arranging a compressible and suitably curable matrix material between the outer compression panels, and providing for each hollow channel in said curable matrix material a separate center expansion means adapted for internal compression, both further and said compression expanders final cross-sectional dimensions while compressing said compression panels to provide the final outer dimensions of said structure, e.g., a plate. The invention also relates to an apparatus for producing a plate made of a compressible material, the plate having one or preferably a plurality of adjacent substantially longitudinal channels, said device comprising an arrangement of outer pressure panels and intervening channel center expanding means interposed therefor. wall portions movable outwardly in a substantially parallel arrangement relative to the central axis of said expander means for compressing said matrix material to the final dimensions of said plate.

Finnish patent application no. 943519 discloses an arrangement in which a special press arrangement is used for the production of cement-fiber boards. Said arrangement comprises retractable internally compressed hub expanders to form hollow channels in the sheet to be made, and carbon dioxide is fed through said internally crimped hub expanders 101054 2 for rapid curing of the cementitious binder.

Hollow channel cement fiber boards are excellent for many structural purposes, but in some cases there is a need to obtain a wood-based material that is easier, e.g., to cut and join together with conventional carpentry tools and methods. Therefore, all kinds of particle board have a well-established position among carpenters and other craft professionals.

A common particle board comprises a mixture of wood chips and an adhesive, and such a matrix material is pressed between hot press panels to form a board having generally flat opposing surfaces, the inner portion of the board being more or less compressed and uniform. The adhesive used to make particle board was previously a formaldehyde-based adhesive that was cured by heating, but today less harmful adhesive components are used for the same purpose. The thickness of such fibreboards is usually 6 to 32 mm. Thicker boards pose a problem because it is difficult to apply the effect of opposing press panels to the central portions of the relatively thick board, and thus the thick board becomes structurally unstable due to insufficient compression and bonding between wood chips in the key portions of the board.

The object of the present invention is to expand the range of board types by presenting a wood fiber board with hollow channels which extend longitudinally between opposite board surfaces. This also includes and in particular plates with a relatively long distance between these opposite plate surfaces, such as e.g. 100 ... 300 mm.

The result according to the invention is achieved by using the method and apparatus set out in the appended claims.

3 101054

The invention generally comprises modifying the arrangement according to the above-mentioned Finnish patent application by using an adhesive instead of a cement-based binder, and by assigning heating means for rapidly curing the adhesive while compressing the matrix material to achieve the final shape of the sheet. Thus, the method of the invention is characterized in that said curable material comprises a thermosetting adhesive, and the method further comprises providing said adhesive with a heating effect to rapidly cure the adhesive before removing said compression center expanders.

The invention will now be described in more detail with reference to the embodiments shown in the accompanying drawings, wherein

Figure 1 shows a schematic view of an arrangement according to an embodiment of the invention,

Figure 2 shows a sectional view of a plate made in an alternative embodiment in which the hub compression expander has a triangular cross-section,

Figure 3 shows an embodiment of a center compression expander means for making the triangular cavity portions of Figure 2;

Fig. 4 shows how the center compression expander means of Fig. 3 are located in the matrix material before the expander is withdrawn from the fabricated sheet.

Figure 5 shows an alternative embodiment of a hub compression expander means, and

Figure 6 shows the center compression expander means in the retracted position within the matrix material.

4 101054

Generally, with reference to Figure 1, the arrangement according to the invention comprises a lower press element 1, an upper press element 2 and suitably side press elements 3, 3a for pressing a curable matrix material 4 between these elements 1, 2, 3 and 3a to produce a plate 5 comprising a hollow core. Figure 1 further shows a plurality of adjacent center compression expanders 6, 6a arranged within the matrix 4 to form, after curing of the curable matrix material, hollow core portions 7, 8 extending longitudinally through the plate 5 (see also Figure 2).

The embodiment shown in Figure 1 comprises hollow core portions or channels of substantially rectangular cross-section. However, a particularly preferred embodiment of the invention, which is particularly useful for structural purposes, comprises hollow channels 7, 8 having a generally triangular cross-section, as shown in Figure 2. This triangular channel shape gives intermediate wall portions 9, 10 which are respectively inclined in pairs. The tilting of these wall portions 9, 10 in practice gives the plate an exceptionally high resistance to shear forces, and thus such a plate can be advantageously used for a variety of structural purposes.

According to the invention, the curable matrix material comprises a base material, which preferably consists of wood chips or the like, which is preferably relatively easy to machine with ordinary hand tools. During the process according to the invention, a thermosetting adhesive is mixed with the base material, which is then cured together to form a uniform material together with the base material. Thus, the curing procedure of the invention comprises the step of heating the adhesive and / or base matrix to a remarkably high temperature while applying pressure to said matrix material to bring the wood chips or the like into intimate contact with each other while compressing the material into its final shape.

The pressure is normally obtained by moving the upper compression panel 2 towards the lower compression panel 1. In this respect, the compressive force generally corresponds to the forces normally used in the manufacture of fibreboards. References to 'upper' and 'lower', respectively, are intended only as a simplifying sentence to make Figure 1 more comprehensible, and in some embodiments the pressure panels may in fact be arranged and oriented in a different way, e.g. vertically. In the embodiment shown in Figure 1, the upper pressing panel 2 is preferably pressed towards the lower pressing panel 1 until it reaches the side pressing panels 3, 3a. At this stage, the side compression panels 3, 3a are moved inwards to form the edge portion 5 of said plate between them. In the embodiments shown in Figures 1 and 2, these plate edge portions preferably comprise groove-tongue deformations 11, 12 known per se.

The inner part of the plate acquires its hollow core structure when adjacent center compression expander elements 6, 6a are used in a manner known per se from Finnish patent application no. 943519, but unlike said patent application The temperature used is typically in the range of 100 to 200 ° C, most preferably about 180 to 190 ° C.

*

As such, the heat can be applied in various ways, most of which in fact also comprise heating at least the surface portions of some of said pressing means 1, 2, 3, 3a and 6, 6a. The heating should be applied substantially simultaneously with said compression. Depending on the adhesive, the procedure is actually very fast, usually about 5 to 10 seconds, preferably about 8 seconds,, 101054

O

for each millimeter of cross-section of the wall material. This would also require a plate with relatively thick wall sections, e.g. a wall thickness of 32 millimeters, to have a heating / pressing time of only about 3 minutes.

In practice, there are several methods for applying heat to a matrix. Thus, one embodiment comprises heating means arranged on each of the pressing elements 1, 2, 3, 3a and 6, 6a. These heating means are generally indicated by reference numeral 13, and may comprise electric heating means, means for blowing hot air or steam, or the like.

One problem which arises when heating only said pressing means 1, 2, 3, 3a and 6 is that the external heating applied to the matrix material 4 also tends to dry it and thus adversely affect the curing of the adhesive. Therefore, an embodiment is preferred in which the required heat is actually applied by blowing a hot flowing medium, e.g. hot air or steam, preferably supersaturated steam, into the matrix material 4 and preferably through it. This can be conveniently done before the adhesive has hardened by compressing said flowable medium at least every other center. ' 'through the inner portions of the compression expander means 6 and suitably by removing said flowing medium through external compression elements and e.g. hub compression expanders 6a spaced apart.

By using supersaturated steam for this purpose, the temperature can be kept high while allowing the addition of an activating agent necessary for the curing process of the liquid, e.g. water or adhesive. According to a particular embodiment of the invention, said matrix material consists at the beginning of the process mainly of wood chips or a similar easily compressible base material, while components important for the curing of the adhesive, in some embodiments even at least 7101054 some components of the adhesive itself, are fed into said matrix medium. touching.

When the center compression expanders known from the said Finnish patent application No. 943519 are as such useful for boards with hollow core channels of considerable dimensions, e.g. in the order of 100 ... 300 millimeters, these devices are unnecessarily complex for the production of smaller scale boards and unnecessarily complex. Figures 3 to 6 show examples of embodiments of center compression expanders used for core channels with a small cross-section. In these embodiments, the main interest is in fact not in the high compressive force, but in the fact that said expanders can be easily reduced and removed from the hollow core channels once the sheet material has hardened.

Thus, Fig. 3 shows a triangular center compression expander element comprising wedge means 14, 15 cooperating with wall elements 16 and corner wedges 17. Said corner wedges 17 preferably comprise a rounded end portion which uniformly acts on the matrix mixture and which avoids unnecessary stresses in the finished sheet product. Figure 3 further shows the channels 18, which connect. · Keskiönpuristuslaajenninelementin with the interior of the outer side. The flowing medium pressed into or withdrawn from said interior will then pass through these channels 18. Since the absolute smoothness of the inner wall of the small longitudinal hollow core channels 7, 8 of the plate 5 is generally less important, according to an embodiment of the invention, generally longitudinal distribution channels 19 are provided on the outer surface of the center pressing element. The central wedge beam 20 preferably also comprises a central bore and channels 21 connecting this bore to the space 22 between the wedges and the wall elements 16.

Figure 4 shows the center press of Figure 3 positioned in the matrix material 4. The center press is shown in a collapsed state and ready to be pulled off the plate 5. This procedure step occurs when the matrix material has cured. In the embodiment shown, said central wedge beam 20 is displaced longitudinally with respect to the general dimension of the center compression expander. Thus, its outermost portions are pulled away from the inner walls forming the hollow core portion 7, 8 of the plate 5, as can be seen from the figure. In one embodiment, the contraction is promoted by means of counter-wedge means suitably located in connection with said wedges 15. When the center compression expander is in its retracted state, it can be pulled off the plate 5.

The center compression element shown in Fig. 5 comprises, on the other hand, collapsible wall portions 23 connected to each other at the corners and through hinge means 24, 25 arranged in the middle of the wall field. These wall portions are somewhat tiltable due to the central rotatable eccentric means 26 which act e.g. directly on the inner surfaces of said wall portions 23, while flexible pushing means 27, e.g. spring means or rubber buffers , which makes it possible to remove the center compression expander. This position of the wall portions is shown in Figure 6.

When hot steam is used as the heating medium, the supply of this medium is preferably effected via the central portions of the center compression expanders. Fig. 5 shows one embodiment in which the channels 28 connect the inner portions of the expander with the outer wall surfaces, allowing heating and / or curing medium to flow into the matrix material around the inside of the centrifugal expander, and in the opposite direction, e.g. with a vacuum. In corner sections, these 9 101054 effects are preferably achieved by the use of generally loosely fitted hinge structures.

In another embodiment (not shown), the medium is fed through bores in the outer compression panel elements 1, 2, 3 and 3a, the center compression expanders acting as suction channels to maintain vacuum conditions in the matrix material. In order to ensure the supply of heat also to the wall portions located between the adjacent hub expanders, it is then considered advantageous that at least every other hub press also at least momentarily also supplies a pressurized hot medium.

In some embodiments, it has been considered sufficient to maintain only the flow of hot medium directly through center compression expanders, e.g., through longitudinal bores 29, some of which are shown in Figure 5, without directly forcing any medium into the actual matrix material 4. In such embodiments with a sock made of material to prevent the matrix material from penetrating the compression mechanism. In another embodiment of the invention, the entire pressing device is maintained under hot pressurized conditions.

The arrangement according to the invention provides a completely new type of board, which as such can be used especially for structural purposes, such as erecting walls, floors, ceilings and the like. The invention avoids the need to connect separate simple two-dimensional plates in general.

t I

• to form three-dimensional structures. Still, the advantage of easy machinability can be maintained.

The sheet made according to the invention has the particular advantage of high strength combined with low weight. The dimensions of the plate are still quite freely adaptable to suit the purpose. Thus, a preferred embodiment comprises a sheet as such having dimensions and strengths directly adapted for the floor structure, with a total thickness of about 300 millimeters. On the other hand, the second plate may have dimensions suitable for general use, e.g. as a wall element, where the thickness may be less than 100 millimeters.

It should be noted that the above description is intended only to give an example of the preferred embodiments, and that the invention may be modified in many ways within the scope of the appended claims.

Claims (10)

11 101054 A method of manufacturing structures, in particular sheets (5), having at least one, preferably a plurality of adjacent hollow longitudinal channels (7, 8) arranged between the outer sheet portions, the method comprising the steps of providing a compressible and curable matrix material ( 4) between the outer compression panels (1, 2, 3) and, for each hollow channel (7, 8), separate center expansion means (6, 6a) adapted for internal compression are arranged in said curable material (4), and these center compression expansion means are expanded (6, 6a) to correspond to the final cross-sectional dimensions of said channels (7, 8) while applying pressure to said compression panels (1, 2, 3) to obtain a structure such as the final external dimensions of said plate (5), characterized in that said curable matrix material (4) contains heat and that the method further comprises applying a thermal effect to said adhesive to rapidly cure said adhesive prior to removing said center expansion means (6, 6a) adapted for internal compression from said hollow channels. * A method according to claim 1, characterized in that a mixture of wood chip material or the like and an adhesive is used as said compressible and curable matrix material (4), said adhesive preferably being a thermosetting agent; wood glue based on, for example, formaldehyde or similar components. Method according to claim 1 or 2, characterized in that at least the surface of said matrix material (4) is maintained at a temperature of 100 to 200 ° C, more preferably 180 to 190 ° C, preferably for a period corresponding to 5 to 10 seconds, preferably about 8 seconds for each millimeter of compressed material corresponding to the final dimensions of said structure, such as the plate (5). 12 101054 Method according to any one of claims 1 to 3, characterized in that said thermal effect is provided at least in part via said compression panels (1, 2, 3) and / or said center compression expansion means (6, 6a), suitably by compression wall portions ( 16, 23). Method according to any one of claims 1 to 4, characterized in that said thermal effect is achieved by blowing a hot fluid through the mass of said curable matrix material (4), and preferably removing excess medium through at least some surface portions of said compression panels and / or center compression expansion means. A method according to claim 5, characterized in that said curable material is formed in the form of a substantially dry matrix and moisture is added to the dry matrix during or after the compression procedure, suitably utilizing the moisture of said fluid, preferably so that said adhesive and / or the hardener is fed in connection with or contained in said medium. Method according to claim 6, characterized in that hot air and / or steam, preferably supersaturated steam, is used as said fluid. Method according to one of Claims 1 to 7, characterized in that at least part of the procedure is carried out under overpressure conditions. Apparatus for making a plate (5) or the like from a compressible and curable matrix material (4), the plate having one or more preferably a plurality of adjacent substantially longitudinal channels (7, 8), said apparatus comprising outer compression panels (1). , 2, 3) and an arrangement of central expansion means (6, 6a) adapted for internal compression of the channels therebetween, the central expansion means comprising wall portions (16, 23) movable outwards and inwards in a substantially parallel position relative to said means ( 6, 6a) on the central shaft (AA) for compressing said matrix material (4) to the final dimensions of said plate (5), characterized in that means are provided for conveying the pressurized hot fluid to be brought into contact with said channels (7, 8). with said matrix material (4) for activating and / or accelerating the curing process of an adhesive-type curing agent connecting individual particles or groups of particles of said matrix material (4). Apparatus according to claim 9, characterized in that said conveying means are adapted to supply and / or remove said hot fluid medium through openings (18, 19, 22, 28) in the walls of said centrifugal expansion means (6, 6a) and / or through said outer press panels. (1, 2, 3) through openings in the walls. * <4 '14 101054