AU644778B2 - Method for the manufacture of load-carrying elements including pallets - Google Patents

Description

C PcRRErIEf VERSION *I P)cT Corrections: under INID Number (81) Designated States insert: AT (European patent), CH (European patent), I DE (European patent), GB (European patent), SNL (European patent), SE (European patent) L5 i INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 5 (11) International Publication Number: WO 90/04679 D21J '/O0 Al (43) Intenational Publication Date: 3 May 1990 (03.05.90) (21) International Application Number: PCT/DK89/00251 (81) Designated States: AT, AT (European patent), AU, BE (European patent), CH, CH (European patent), DE, DE (22) international Filing Date: 25 October 1989 (25.10.89) (European patent), FI, FR (European patent), GB, GB (European patent), IT (European patent), JP, KP, LU (European patent), NL, NL (European patent), NO, SE, Priority data: SE (European patent), US.

5923/88 25 October 1988 (25.10.88) DK Published (71) Applicant (for all designated Sta'es except US): BRO- With international search report.

DRENE HARTMANN A/S [DK/DK]; Klaapenborgvej 203, DK.2800 Lyngby (DK).

(72) Inventor; and Inventor/Applicant (for US only) RASMUSSEN, Torben j [DK/DK]; Christoffersalle 63, DK-2800 Lyngby 6 (74) Agent: BUDDE, SCHOU CO.; H.C. Andersens Boulevard 4,V, DK-1553 Copenhagen V (DK).

(54) Title: METHOD FOR THE MANUFACTURE OF LOAD-CARRYING ELEMENTS INCLUDING PALLETS (57) Abstract By means of a procedure for the manufacture of load carrying elements, including pallets, a fluidized fibre raw material is deposited on a moulding foundation through suction of a pulp of the fibre raw material on that foundation. For this purpose the foundation is applied with an easily drainable pulp created by the fluidized fibre raw material in such an amount and the suction is carried out controlled in such a way that on the foundation through suction a fibre raw material is deposited having such wall thickness that substantially provides the desired load c~paciy of the element.

S(Referred to In PC' Gazette No. 1611990, Section II).

HA/ELI 48560 Pallet Brodrene Hartmnann A/S, 2800 Lyngby, Denmark Procedu~re for the manufacture of load-carrying elemnents, including pallets BUDDE, SCHOU CO.

Copenhagen, 25 October 1988 *9 9 9 9 99 9.

9 99.9 99 99999 0 9S 9. 9 *99 9 9 The present invention concerns a method for the manufacture of load-carrying elements, including pallets by the depositing of a fluidized fibre raw material on a moulding foundation by suction of a pulp of the fibre raw material on this foundation.

A fluidized fibre raw material means a starting material, which may be in wet form, of a fibrous nature and suited for the manufacture of the desired objects.

Such starting material may for instance be a fibre pulp material as used for instance for trays and cartons for packaging of fragile and sensitive objects such as fruit, flowers, eggs and objects of for instance glass.

The pulp material usually consists of a suspended, fibrous cellulose.

It is well known for this purpose to use a production technique by which the starting material in the form of a pulp is by a depositing process placed against the outline-forming outside of a mould which is permeable to let a gaseous working medium, through a suction effect, affect the material throUgh the material of the mould and thus mould the contour of the material on the mould through suction.

The object of the invention is to indicate how this in itself suitable production technique may be used not S 25 only to manufacture relatively small and light objects but also to manufacture large, rather heavy objects S• characterized by extremely high load capacity which are 9 substantially based on a corresponding thickness of the material layer deposited on the moulding foundation. In comparison with this the wall thickness of the said small and light objects is rather thin and the rigidity necessary in practice is usually obtained by deliberately forming the wall panels which for instance support the said objects as the walls produce a rather rigid total S 35 object by mutually supporting each other.

The present invention provides a method for the manufacture of load carrying elements, including pallets, by depositing of a fluidized fibre raw material on a 2 form-giving foundation by means of suction of a pulp of the fibre raw material on the foundation, said method being characterised in that the pulp is prepared from raw material which has selectively been elected to contain a long-fibred starting material and which by making use of said long-fibred material provides improved drainability, the pulp being applied to said foundation in such quantities, and the suction being carried out and controlled in such a way, that there is deposited a fibre raw material layer with such all thickness that the element so obtained has the desired load capacity.

This will by using the above production technique also enable the manufacture of elem-nts with high load capacity such as pallets and building elements which may, contra-y to the said packaging examples, display rather even and smooth outer surface and which in themselves display a high degree of form stability. The depositing of a fibre raw material layer of the defined thickness means that the negative pressure in the fibre raw material layer used for suction may procure a material density which is highest at the outside of the material layer directed towards the mould surface and which will have a reinforcing effect as ;I*la it is placed at a distance from the through-going centre plan of the deposited object.

25 By using the layer thickness of the element thus manufactured its load capacity may according to the oinvention also be increased by procuring in the fibre raw material layer and distributed over this one or more variations in the layer thickness by means of the suction 30 effect's being correspondingly varied locally in a common suction process for the fibre pulp quantity necessary for ooo the manufacture of the whole element. In this way it will be possible in one and the same working process, i. the depositing of the fibre raw material on the moulding 35 foundation, to mould both the final outside desired for the element and, by using the thickness of the material layer, a load capacity increasing moulded structure in the actual Smaterial object forming the 3 element. The fibre raw material may be deposited with a thickness corresponding to the desired load capacity, there being formed connected regions that have a larger wall thickness in comparison with the other regions of the element.

For suction of an easily drainable pulp of the fibre raw material. in the desired thickness, a mould may be used which at negative pressure is permeable by a gaseous active working medium, and which has a mould surface that is permeable by a working medium, the thickness of which mould surface is selected according to the thickness of the fibre raw material layer to be deposited by suction of the pulp on the surface.

In this way it is possible to achieve such interaction between the draining ability of the pulp and the suction capability of the mould surface that also elements having thick fibre layer thickness owing to the desired load capacity may be manufactured rationally.

In order to achieve local variations in the layer thickness of tle fibre raw material layer of the element, there may br used a mould, the mould surface of which has a permeability which varies in accordance with the desired variation of the wall thickness or, respectively, with the desired configuration of connected regions of V1 ,0 25 the easily drained fibre pulp layer deposited by the S suction on the mould surface.

This means that the depositing of fibre raw material on the mould surface w.ll vary according to the permeability of this surface which results in local variations in the suction effect which, in areas with poor mould surface permeability, causes reduced depositing of fibre raw material on the mould surface whereas the depositing will be high in areas with high mould surface permea- [bility.

35 In one embodiment of the invention there is used for the suction of the easily drainable pulp of the fibre raw S' -material in the desired thickness a mould which at negative pressure is permeable by a gaseous active 4 working medium, of which mould at least a contour-forming part is built up from a particulate composite material which is present in flowable form, and the particles of which are bound together partially by means of a binding agent and/or provide a coherent supporting skeleton or framework connection with each other for the formation of a form-stable outline in a stable structure and between them define open passages for the working medium extending from the interior of the mould through the material of the mould and to the outer surface of the mould, the thickness of at least the composite material layer forming the mould surface being selected according to the thickness of the fibre raw material layer to be deposited by suction of the pulp on the mould surface.

Such a mould may be manufactured on the basis of a cheap, inorganic raw material such as sand as well as by means of a production technique which is simple, of short duration and thus also cheap. The total production costs of the mould may thus be kept at a low level and this form of construction will consequently be suitable for the production of a small number of products.

In order to achieve local variations in the layer thickness of the element's fibre raw material layer a mould may, according to the latter procedure, be used in 25 which the composite material formed by the mould surface has a thickness that varies in accurdance with the '0 desired variation of the layer thickness or, respectively, with the desired configuration of connected regions of the easily drainable fibre pulp layer deposited on the mould surface by suction.

There may be used a mould, the permeable mould surface of which is composed of particles of different particle sizes, the particle size being small in a part sees providing the mould surface and larger in an underlying 35 supporting layer for this part. In this way it is pos- 'sible to procure good passage for air and at the same time procure for the element to be manufactured a rather smooth mould outside which will result in the element's 5 obtaining an even surface.

The mould strength necessary for the carrying through of a production process may be achieved in a simple way by mixing the mould particles with suitable binding agents. The binding agent may contain an' adhesion-improving agent. The binding agent may be thermo-setting. The mould manufactured by mixing the particles with suitable binding agents may be hardened by for instance heat treatment. The particles may have a rounded outline. Also wedging between the particles may be used to give the mould strength.

Furthermore, according to the invention it is possible to use a mould having at the bottom a base in which the composite particles are fused together, while the particles of the rest of the mould are linked to each other by a hardening adhesive compound. Such a mould is characterized by good strength which will also enable it to resist considerable working pressure.

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-6 It is also within the scope of the inventiop to use a mould,.the mould surface of which is designed with such strength that the mould can be used for finishing pressing of a moulded element. Finishing pressing may riot only be used for quick removal of water from the pulp layer deposited on the mould surface, but also to achieve an especially good material density in the deposited, rather thick fibre material layer and thus an especially high degree of form stability in the final element.

The desired porosity of the mould may b' achieved by an appropriate choice of the size and distribution of the particles of which the permeable mould surface may be composed both to obtain favourable conditions for the fixing compound between the particles and for a suitable dimensioning of the porosity in order to avoid undesired pressure drop through a building material which is unnecessarily dense.

The above procedure and mould may as mentioned in practice be used for the production of elements of various fibre-containing suspensions, everything in the presence of the auxiliary materials which may be necessary to create connection in the material layer obtained by suction onto the mould.

o The removal of an object formed by the depositing of 25 a fluidized fibre raw material on the outline-forming out- S" side of the mould surface by means of a gaseous wo:king medium -ay in practice take place by the object being affected o by compressed air through the air passages of the mould and thus lifted free of the mould. In practice the object will, S 30 however, usually still be rather soft and it may therefore for the purpose of removing the object from the casting mould be appropriate to use a transfer mould which is adapted to interact with the side of the object pointing away from the mentioned outline-forming outside for the removal 35 of the object from this outside and for the subsequent placing -7of the object on for instance a conveyer belt taking the object to a drying chamber. It is within the scope of the invention also to manufacture such a transfer mould from a particle composite material as mentioned above by binding the material particles together with the creation of an open, stable structure with air passages going through to the outside of the mould and by connecting the thus created mould to, a source for a suction provoking vacuum.

The transfer mould is producible directly on the basis of an object produced on the casting mould as on this object a first auxiliary mould (negative) of for instance gypsum is produced corresponding to the side of the object pointing away from the casting mould and on this first auxiliary mould (negative) a second auxiliary mould (positive) is produced for instance-also from' gypsum and the transfer mould (negative) is then formed directly on this second auxiliary mould.

The permeable mould surface may be kept clean by, prior to the start of the depositing process or the transfer process, exposing for cleaning purposes the mould surface to an air current passing through the mould passages for a gaseous medium.

A mould used in accordance with the invention and constructed by a particle composite material may be manu- 25 factured in such a way that it may after use or in case of wear by regenerated as the particle-shaped building material of the mould may be recycledH For the manufacture of a pulp is to be easily drained, according to the invention, there is used as fibre raw material at least partly a long fibre starting .material which is processed to a pulp partly by means of a shake-out in a pulper, partly by a preceding, separate, controlled dry grinding process, by which the starting material is separated into portions and divided into fibres, the element being manufactured from the pulp thus created.

The use of a pulper as an essential step in the processing of the fibre raw materials for the creation of a 8 pulp from which the desired objects are to be manufactured takes place among other things in cases where the fibre raw materials are received in the form of dry substances in bales, for instance as paper waste.

Heavy whirl formation is produced in the pulper by which the single parts of the material rub against each other and is thereby,,divided and the raw materials separated into fibres.

Especially in case of heterogeneous material such as waste or recycled paper it has to be anticipated that this separation is carried out successively so that the fibres released first are exposed to a higher degree of additional substantial processing than the fibres released later. In other words the processing in the pulper will in its proceedings thus be uncontrolled and thus heterogeneous. The said additional processing results in an increase in both the degree of grinding (OSR-Schopper-Riegler) and thus the formation of mucus in the pulper, which negatively affects the subsequent draining of -he element manufactured from the pulp and increases the shrinkage of the element during draining and drying of its material.

The method according to the invention achieves that to the pulper is at least partly added a fibre raw material the S fibres of which are already to a substantial degree se- 25 parated into single fibres so that they are more instant and at the same time susceptible to the self-grinding effect and mixing effect obtained in the pulper. As the pulper proces- -es a more uniform raw material also the grinding degree obtained in the pulper through self grinding may be adjusted 30 to be more uniform and the above-mentioned binding of water in the pulp leaving the pulper will thus be more controllable.

The same procedure will, however, also result in other advantages which are especially valuable in case of recyc- 0. 35 ling of paper waste.

Recycled paper waste exists in many different qualities and gradings. If this material prior to the shake-out in the 9 pulper is exposed to a separate, controlled dry grinding, it is often possible to use a purer and thus cheaper material quality, than if the division process was only carried out as a shake-out in the pulper.

The preceding, separate, controlled dry grinding process may be carried out as a multiple-stage process, whereby it is possible to separate the starting material in portions in an e pecially efficient manner.

In this particular way also e.g. waste paper material containing plastic, water resistant paper, plastic laminated cartons and paper, can to the degree desired be separated into fibres and other particles.

Separated constituents not being paper can be screened off before entering the pulper, or it is possible to let these constituents since they exist in pulverized form enter into the subsequent production process.

In one embodiment of the method, a long fibre starting material that has been subjected to a separate controlled dry grinding process may be added in portions to a pulp already created in the pulper and may be subjected with said pulp to a shake-out of limited duration.

In this manner an element can be manufactured, the fibre material of which is partly bound by inter-fibre 25 hydrogen bonding, partly mixed with air suspended fibre material for the binding of which glue is normally used.

It has turned out that in this way it is possible to abandon a traditional complete hydrogen binding of the whole pulp, which means that the drain and thereby the 30 production time for the object can be substantially reduced. Furthermore the method makes it possible to obtain a strict control of the desired object strength characteristics as it will be possible to have strict control of these by the addition of glue.

35 These advantages are of major importance for a rational and thus economic industrial manufacture also of large, form stable objects by the application of the suctioh technique described.

10 It will e.g. be possible to carry out a multiplestage dry grinding by the application of a tearing machine also called a shredder, followed by a treatment in a hammer mill which thus can receive the material from the shredder in portions and which exposes the material to a further grinding process before it, if required also in selected portions, is added to the pulper for the actual shake-out processing.

The separate, controlled dry grinding suggested according to the invention of the fibre raw materials prior to their shake-out in the pulper also provides the possibility for the co-application of recycling waste paper in cases where the elements to be manufactured must be shrink proof and measure proof. A starting material with a high content of wooden fibre causes less shrinkage than if the fibre were cellulose fibre. It has turned out that by applying the method according to the invention it is even possible to add to a wooden paper raw material a substantial amount of cheap recycling paper including carton waste which not necessarily is wooden since it is possible to manufacture due to the preceding separate controlled dry grinding of the raw material a pulp which causes no undesired shrinkage of the objects manufactured.

25 It is a well known principle for the manufacture of objects of a fluidized fibre raw material to utilize auxiliary materials such a filling material and chemicals and binding agents. The auxiliary materials decide whether the objects manufactured shall be more or less strong, hard or transparent, or weak, soft and absorbing.

The present invention is also advantageous in connection with the application of such auxiliary materials.

The division of the manufacturing process in multiple-stages actually increases the possibility of 35 adding the auxiliary materials at different stages of the total manufacturing process. The achieved open structure of the final pulp, obtained as a result of this particular invention, even facilitates a better access for a *r a a a *r a a a a a.

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1- auxiliary materials so that e.g. a binding material may be applied more or less integratir:; on the surface of the objects in order to increase the weight. The auxiliary material may be added to the fibre material in the preceding separate, controlled dry grinding process.

That will in arn specially good manner be able to further a particular uniform distribution of the auxiliary materials in the manufactured fibre mass. The auxiliary material may instead be added to the pulp in the pulper.

Furthermore, it lies within the scope of the invention that the shake-out in the pulper is carried out as a manufacturing process dependent on the preceding separate, controlled dry grinding process. In other words the obtained degree of a self grinding in the pulper can be adjusted in accordance with the degree of the grinding which according to the circumstances has been carried out at the preceding dry grinding stage(s). As an exampe, to a paper pulp which in the pulper is separated into a normal, at self grinding obtained grinding degree of 60' SR (Schopper,-Riegler), may be added dry grounded fibre material whereafter the mixture is processed in the pulper for 5 minutes more. Objects manufactured from such a mixture pulp may be provided with a special heavy thickness, porosity and permeability. This means that the i 25 products can have good drain qualities and therefore also can be manufactured with large wall thicknesses.

An easily'drainable pulp manufactured according to the invention facilitates unproblematically a uniform addition of the fibre suspension over the mould even in cases of manufacturing objects with large wall thickness.

Waste paper, also called return paper, may be very cposite, and contain fibre with a large variety of fibre lengths. However, it has actually turned out that the average fibre length is so large that the above mentioned advantages especially as regards drainage and

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structure may be obtained when this paper material forms *i part of the manufacturing process.

The method according to the invention will also be 12 available for the processing of so-called virgin material.

In the following the invention will be explained in detail with r-fdrence to the drawing in which Fig. 1 diagrammatically shows a survey of process proceedings summing up the proceeding phases which niay take place during the proceeding of a process for the manufacture of for instance a pallet, Fig. 2 examples of combinations of varlious phases of process p'-oceedriis, Fig. 3 an inclined presentation of a f irst embodiment f or a load-carrying element in the f orm of a pallet manuf actured by means of the process according to the invention and showing one of the corner parts of the pallet from which the actual corner section is separated, Fig. 4 schematic from the side another embodiment for a pallet, Fig. 5 viewed from the side (Fig. 5b) and sectionally along the line V-V (Fig. 5a) a third embodiment for a pallet, Fig. 6 schematic cross section through a fourth embo- 2Q diment for a pallet, Fig. 7 inclined presentation of a fifth embodiment for a pallet, Fig. 8 schematic cross section through a sixth embodiment for a pallet, Fig. 9 schematic pallet with a tension rope, Fig. 10 schematic pallet with a wooden support rail, 11 schematic pallet with a support rail of fibre raw material, Fig. 12 schematic cross section tChough a pallet constructed from elements of varying layer thickness, Fig. 13 another embodiment for such pallet Fig. 14 a third embodirnenL for a pallet containing a single element of varying layer thickness, ea9 Fig. 15 a cr~oss section through in embodiment for the 35 supporting legs of a pallet, and Fig. 16 schematic a mould with deposited element of f ibre raw,, material, both the mould surf ace and thus also the 13 deposited element having varying layer thickness.

The diagram of proceedings shown in Figs. 1 and 2 comprises a total of fourteen process phases. The production process will, according to the production process, be able to be carried out by the use of all these phases, or only some of the phases, but it may also be a question of using some of the phases and then concurrently introducing the resulting product as a supplement to a coherent production process.

Example 1 All 14 process phases are used.

Example 2 Phase 1 up to and including phase 5 is carried out followed by phases 8 and 9 and finally phases 11 to 14 are carried out.

Example 3 One production line is used from phase 1 to phase and another production line for phase 4 and possibly phases 5, 6 and 7. The wet fibre pulp created in the second production line is added to the product resulting from the first production line. The work is continued with usually several of the subsequent phases.

In this way a product is produced in which the fibre material manufactured in the second production line is 25 mainly bound by inter-fibre hydrogen bonds whereas the first production line produces a fibre material suspended in air and to the binding of which glue is normally used.

In this way it is possible to achieve a total degree of grinding, which is optimum, and simultaneously an optimum 30 addition of glue. This means that this embodiment for :o o the process allows comprehensive consideration of the quality of the available raw material.

In the ftllowing some embodiments for pallets will be described. The pallets are manufactured by means of

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the process according to the invention.

14 As shown in proceeding diagram in Figs. 1 and 2 the pallets are manufactured from a suspension of a fluidized fibre raw material as the suspension is in an aqueous phase deposited by suction on a contour-shaping foundation. As described above an easily drainable pulp is created from the fluidized fibre raw material. This pulp is deposited on the contour-shaping foundation in such quantity, and the negative suction pressure used for depositing of the pulp on the foundation is controlled in such a way that a fibre raw material layer is deposited on the foundation in such thickness that this in all essentials achieves the load capability desired for the element, i.e. in the present case the pallets.

The water content of the applied pulp may be up to p.c. and this water content may then be removed by pressing and/or drying. As the load capacity of the end product, the pallets, is substantially to depend on the thickness of the fibre raw material layer deposited on the contour-shaping foundation, it is an essential prerequisite of a economical production that the employed pulp is easily drainable. The invention comrises a procedure for the production of a pulp with this property.

The end product may then be used as it is or it may to- :a gether with similar products form part of another end pro- 25 duct, for instance in the form of a laminate construction.

Experience has shown that it is possible in this way S. to manufacture pallets with a low net weight of 5 to 8 kg for a pallet size of 800 x 1200 mm and with a carrying capacity of approx. 500 kg. The carrying capacity will depend on the quality of the employed fibre suspension and of the actual pallet's structural design of which some examples will be given in the following.

Fig. 3 shows schematically part of a pallet 10 designed with integrated legs and with strengthening ribs.

35 Example measurements 800 x 1200 x 120, shaped three dimensionally in a single working process with "wet" weight 18 kg and weight after drying 6 kg.

Example measurements 800 x 1200 x 120, shaped three dimensionally with "wet" weight 18 kg, weight after heat pressing 12 kg and weight after drying 6 kg.

Fig. 4 shows schematically a pallet in the form of a laminate as the pallet has a bottom part 16, which substantially corresponds to part 10 in Fig. 3, and an upper, even cover plate 18, which is also designed in accordance with the procedure according to the invention.

Example measurements 800 x 1200 x 123, part 16 of the pallet is shaped three dimensionally with "wet" weight 12 kg and weight after drying 4 kg. The cover plate 18 is manufactured on an even moulding surface: "wet" weight 6 kg, weight after heat pressing 4 kg, weight after drying 2 kg.

The cover plate 18 is glued to the top side of bottom part 16.

The cover plate 18 may have holes for the reception of the legs from a pallet lying in a pile above.

Fig. 5 shows a pallet of the same type as shown in Fig.

4, however, with the difference that the upper part 20 of the pallet is shaped three dimensionally with strengthening ribs 22 which correspond with the shaped rib parts 24 in the bottom part 16. Measurements 600 x 800 x 140.

Example the under side 16 of the pallet is designed e.

S: with "wet" weight 7.5 kg and weight after drying 2.5 kg, &nd '5 the upper part of the pallet is designed with "wet" weight 4.5 kg and weight after drying 1.5 kg.

Fig. 6 shows a pallet, measurements 800 x 1200 x 150.

Example The pallet has a three dimensional centre part 26 with "wet" weight 6 kg and weight after drying 2 kg 30 as well as two cover plates 28 each shaped on an even mould- I ing surface and with "wet" weight 6 kg, weight after heat pressing 4 kg and weight after drying 2 kg. Furthermore, the plate has nine three dimensional legs 30 with "wet" weight of each 0.3 kg and weight after drying 0.1 kg. Glue for as- 1: :35 sembling of cover plates and legs 0.05 kg. Finished product S'i weight: 6.95 kg.

Fig. 7 shows a pallet, measurements 800 x 1200 x 150.

-16- Example The pallet is composed of two uni,-Tm, three dimensional plate elements 32 each having hollow projections 34 projecting transversely to the plate part. The plate elements are mounted with their projections 34 pointing towards and lying against each other.

Each plate element 32's "wet" weight is 9 kg, weight after drying is 3 kg, each has nine 100 mm tall legs, "wet" weight of each 0.3 kg and weight after drying 0.1 kg. Glue for assembling 0.05 kg. Weight of the finished product: 6.95 kg.

Fig. 8 shows a pallet containing two trapeze profiled centre plates 36, whose ribs 38 cross, and two outside, even cover plates 40. Legs, which are not shown, are glued to one side f these plates.

Both the trapeze shaped and the even plates 36 and respectively, may be manufactured either by the piece by discontinuous moulding or continuously on continuous belt followed by respectively even or trapeze profiled male and female stamping rollers. This results in a high degree of flexibility for the production of the pallet as it is possible to choose a larger or smaller number of plate layers which furthermore, owing to the pressing process, only re- S suits in low drying costs.

Example Two trapeze profiled fillers 36 with "wet" 25 weight after moulding 4.5 kg, "wet" weight after pressing 3.0 kg and weight after drying 1.5 kg. Two even cover plates :0 40 with "wet" weight after moulding 4.5 kg, "wet" weight after pressing 3.0 kg and weight after drying 1.5 kg. Nine legs (not shown) each with "wet" weight after moulding 0.3 30 kg and weight after drying 0.1 kg. Glue for assembling 0.05 kg.

In the stated embodiments the plate parts and legs of the pallets may be shaped together in a joint suction operation or they may be shaped in separate suction operations.

35 The legs may also, where desired, be manufactured from another material than fibre raw material but experience has shown that by using the procedure according to the invention 17 it is possible to manufacture legs with sufficient load capacity and robustness and at the same time low weight, as stated in the examples.

Furthermore, the process according to the invention makes it possible without problems to add to the fibre pulp special reinforcement fibres where an especially high degree of strength is desired.

In the design of the elements it is also possible to consider the placing of additional, outside straining agents. Figs. 9 to 11 show some examples of load-carrying elements in the form of pallets as a common support rail 44 of for example wood is placed, as for instance shown in Fig.

under the legs of the pallet, or as shown in Fig. 11 the use of a special pallet frame 50 composed by legs 46 and a common support rail 48 and manufactured from the same material as the pallet's plate part 52.

As already mentioned the invention's characteristic depositing of a fibre raw material layer of such thickness that this essentially produces the load capability desired for the element renders the opportunity of exploiting the layer thickness for an additional increase in the load capability in the way that in the fibre raw material layer variations are made in the layer thickness, for instance as :i a coherent structural pattern. This means that by means of 25 variations in the layer thickness, £fQ- instance rib-like formations are created in which the layer thickness of the elements is thicker than in the other arias of the element.

If the forming and arrangement of such or similar formations are suitable, an increased rigidity may be achieved in the 30 element whereby its load capacity is increased.

Figs. 12 to 15 show examples of such variations. As also mentioned above such variations are achieved by using a mould which at negative pressure is permeable by a gaseous active working medium which mould has a mould surface, permeable by the working medium, with a permeability varying in accordance with the desired variations in the layer thickness of the layer.

-18- Fig. 12 shows a cross section of a pallet constructed from two rib profiled interior elements 54 which on the outside are covered by two even cover plates 56. Each interior element 54 has been manufactured in one single woirking process from a fibre raw material which is deposited on the mould surface of the suction mould with a wall thickness varying from rib top to rib bottom the largest wall thickness being at the rib top 54a and the smallest at the rib bottom 54b. The cross section profile cl the rib formation is angular and the interior elements 54 are lying against each other at the top 54a.

Fig. 13 shows a cross section of the same type of pallet with the difference, however, that the interior elements 54 are lying' together at the bottom 54b so that the rib tops 54a carry the cover plates 56.

Fig. 14 shows a cross section of a pallet with only one single interior element 58, which with its tops 58a and bottoms 58b lie against exterior, even cover plates 60. As mentioned, also this interior element 58 is manufactured in one single working process with such variation in the layer thickness that this is largest at the rib top 58a and smallest at the rib bottom 58b.

Fig. 15 shows an example of a supporting leg 62 of a pallet. The leg 62 is pot shaped and manufactured in one 25 single active working process through suction of a fibre raw material as described. Also this element has varying layer thickness and it is ~hicker at the bottom 62b.

Fig. 16 illustiates how such variations in the layer thickness may be achieved according to the invention. As schematically illustrated a mould 64 which at negative pressure is permeable by a gaseous active working medium is used for suction onto the mould surface of the mould of an easily drained pulp created from fluidized fibre raw material, which mould has a by the working medium permeable mould sur- 35 face 66. In accordance with the creation of a rib profiled pallet element 68 in which the material layer is thick in the rib top 68a and thin in the rib bottom 68b a mould with -19 a rib profiled mould surface 66 with varying permeability is used, the mould surface 66 being thick at the mould surface tops 64b and thin at the mould surface bottoms 64a.

This results in the suction effect being weaker at the part of the mould surface created by the mould surface tops 64b than at the part created by the mould surface bottoms 64a.

This will in its turn result in less depositing during suction of the added fibre pulp of fibre material at the mould surface tops 64b which form the rib tops 68a whereby the layer thickness of these and consequently the rib formation created by them achieves a rather high degree of thickness and strength. This production teuhnique may in principle be used in connection with many different variations in the layer thickness and the above-mentioned is only meant as a typical example of this.

The applicability of the invention has been illustrated above by examples of pallets. It may with equal advantage be used also for the production of many other kinds of load carrying elements including wall elements for various purposes, building elements and insulating elements. Furthermore, the above shows that the process according to the invention has opened up for suitable employment of many kinds of starting materials and additives. The invention also opens up the possibility of unproblematic incorporation of foils or reticular objects in the outside of the created object.

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Claims (22)

1. Method for manufacture of load carrying elements, including pallets, by depositing of a fluidized fibre raw material on a form-giving foundation by means of suction of a pulp of the fibre raw material on the foundation, said method being characterised in that the pulp is prepared from raw moterial which has selectively been elected to contain a long-fibred starting material and which by making use of said long-fibred material provides improved n drainability, the pulp being applied to said foundation in such quantities, and the suction being carried out and controlled in such a way, that there is deposited a fibre raw material layer with such wall thickness that the element so obtained has the desired load capacity.

2. Method in accordance with claim 1, wherein the suction is applied to the pulp by way of a suction process, the intensity of the suction being variable across the extent of the layer to produce one or more variations in the wall thickness of the element.

3. Method in accordance with claim 2, wherein the fibre raw material is deposited with a thickness commensurate to :i the load capacity, there being formed connected regions that have a larger wall thickness in comparison with the other regions of the element.

4. Method in accordance with any one of claims 1 to 3, wherein, for suction of an easily drainable pulp of the -fibre raw material in the desired wall thickness, a mould is used which at negative pressure is permeable by a gaseous active working medium, and which has a mould foot, surface that is permeable by the working medium, the thickness of which mould surface is selected according to the thickness of the fibre raw material layer to be deposited by suction of the pulp on the surface.

5. Method in accordance with claim 4, for the carrying out of a method in accordance with claims 2 or 3, wherein a mould is used the mould surface of which has a permea- 21 bility which varies in accordance with the desired variation of the wall thickness or, respectively, with the desired configuration of connected regions of the easily drained fibre pulp layer deposited by the suction on the mould surface.

6. Method in accordance with claim 4, wherein at least a contour-forming part of the mould is built up from a particulate composite material which present in a flowable form, and the particles of which are bound together partially by means of a binding agent and/or provide a coherent supporting skeleton or framework connection with each other for the formation of a form- stable outline in a stable structure and between them define open passages for the working medium extending from the interior of the mould through the material of the mould and to the outer surface of the mould, the thickness of at least the composite material layer forming the mould surface being selected according to the thickness of the fibre raw material layer to be dep- osited by suction of the pulp on the mould surface.

7. Method in accordance with any of claims 4 to 6, wherein a mould is used, the permeable mould surface of which is composed of particles of different particles sizes, the particle size being small in a part providing S. the mould surface and larger in an underlying supporting layer for this part.

8. Method in accordance with claim 6, wherein a mould is used, the binding agent of which is thermo-setting.

9. Method in accordance with claim 6, wherein a mould of*f is used, the binding agent of which contains an adhesion- improving agent. off

10. Method in accordance with claim 7, wherein a mould is used, the particles of which have a rounded outline. l.

11. Method in accordance with claim 6, wherein a mould 35 is used, the particles of which are wedged against one another.

12. Method in accordance with claims 5 or 6, wherein there is used a mould having at the bottom a base in 22 which the composite particles are fused together while the particles of the rest of the mould are linked to each other by a hardening adhesive compound.

13. Method in accordance with any of the claims 4-12, wherein a mould is used, the mould surface of which is designed with such strength that the mould can be used for finishing pressing of a moulded element.

14. Method in accordance with any of the previous claims, wherein as fibre raw material at least partly a long fibre starting material is used which is processed into a pulp partly by means of a shake-out in a pulper, partly by a preceding, separate, controlled dry grinding process, by which the starting material is separated into portions and divided into fibres, the element being manufactured from the pulp thus created.

Method in accordance with claim 14, wherein the preceding, separate, controlled dry grinding process is carried out as a multiple-stage process.

16. Method in accordance with claim 14 or 15, wherein the shake-out in the pulper is carried out as a manufact- uring process in association with the separate, controlled dry grinding process.

17. Method in accordance with any of claims 14-16, Swherein a long fibre starting material that has been S, 25 subjected to a separate, controlled dry grinding process is added in portions to a pulp already created in the pulper and is subjected with said pulp to a shake-out of limited duration.

18. Method in accordance with any of claims 14-17, wherein auxiliary material is added to the fibre material VS S: in the separate dry grinding process. i

19. Method in accordance with any of claims 14-18, wherein auxiliary material is added to the pulp in the pulper. 35

20. Method in accordance with any of claims 14-19, wherein a pulp is manufactured as stated in claim 16, and portions of the pulp so obtained are combined with another already manufactured pulp, and the element is A 23 manufactured from the mixture thus created.

21. Load carrying element consisting of a fluidized fibre raw material, which element has been manufactured by means of a method in accordance with one or more of the claims 1 to

22. Pallet consisting of a plate part and~ connected supporting legs, which pallet has been manufactured by means of a method according to one or more of tLhe claims 1 to SB *eg So to t o o to S 4' 24 Procedure for the manufacture of load carrying elements, in- cluding pallets. SUMMARY By means of a procedure for the manufacture of load carrying elements, including pallets, a fluidized fibre raw material is deposited on a moulding foundation through suction of a pulp of the fibre raw material on that foundation. For this purpose the foundation is applied with an easily drainable pulp created by the fluidized fibre raw material in such an amount and the suction is carried out controlled in such a way that on the foundation through suction a fibre raw ma- terial is deposited having such wall thickness that substan- tially provides the desired load capacity of the element. (Fig. 16). 8-:6 o q 0 ::0 I So IS I