Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21J—FIBREBOARD; MANUFACTURE OF ARTICLES FROM CELLULOSIC FIBROUS SUSPENSIONS OR FROM PAPIER-MACHE
  • D21J7/00—Manufacture of hollow articles from fibre suspensions or papier-mâché by deposition of fibres in or on a wire-net mould

Definitions

• the present invention concerns a method for the manu ⁇ facture 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 mate ⁇ rial, 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.
• the object of the invention is to indicate how this in itself suitable production technique may be used not only to manufacture relatively small and light objects but also to manufacture large, rather heavy objects characterized by extremely high load capacity which are substantially based on a corresponding thickness of the material layer deposited on the moulding foundation.
• 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 object by mutually supporting each other.
• the stated objective is a- chieved by applying to the foundation an easily drainable pulp made of the fluidized fibre raw material in such quan ⁇ tity and by controlling the suction in such a way that a fibre raw material layer of such thickness as to provide substantially the load capacity desired for the element.
• the depositing of a fibre raw mate ⁇ rial 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 out ⁇ side of the material layer directed towards the mould sur ⁇ face and which will have a reinforcing effect as it is placed at a distance from the through-going centre plan of the deposited object.
• the layer thickness of the element thus manu ⁇ factured its load capacity may according to the invention also be increased by procuring in the fibre raw material layer and distributed over this one or more variations in the layer thickness by correspondingly locally varying the suction effect during a joint suction process for the fibre pulp volume necessary for the manufacture of the whole ele ⁇ ment.
• the depositing of the fibre raw mate ⁇ rial on the moulding foundation i.e. the depositing of the fibre raw mate ⁇ rial on the moulding 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 material object forming the element.
• such a structure will for in ⁇ stance be able to be shaped as a connected structural pat- tern with a thicker layer thickness compared with the parts of the element.
• a suitable way for the car ⁇ rying through of the method is characteristic in that, for suction of an easily drainable pulp of the fibre raw mate- rial in the desired thickness, a mould is used which at ne ⁇ gative pressure is permeable by a gaseous active working me ⁇ dium and which has a by the working medium permeable mould surface the permeability of which is adjusted to the thick ⁇ ness of the fibre raw material layer to be deposited by suc ⁇ tion of the pulp on this surface.
• a mould having a mould surface with a permeability varying in accordance with the layer thickness of the local varia ⁇ tion or variations respectively or the coherent structural pattern of the easily drainable fibre pulp layer deposited on the mould surface by suction may be used according to the invention.
• an embodiment of this me- thod may be characterized by the use for suction of an easily drainable pulp of the fibre raw material in the de ⁇ sired thickness of a mould which at negative pressure is permeable by a gaseous active working medium which at least as regards the outline-forming part consists of a partial composite material the particles of which are fixed together for the formation of a contour-stable mould surface at the same time as they together limit passages open to the work ⁇ ing medium, which passages extend through the composite ma ⁇ terial to the outside surface of the mould, and that the thickness of at least the composite material layer forming the mould surface is adjusted according to the thickness of the fibre raw material layer to be deposited by suction of the pulp to this 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 produc ⁇ tion of a small number of products.
• a mould may, according to the latter procedure, be used in which the composite material formed by the mould surface has a thick ⁇ ness that varies in accordance with the layer thickness of the local variation or variations, respectively, or the de ⁇ sired coherent structural pattern of the easily drainable fibre pulp layer deposited on the mould surface by suction.
• a mould may be used the per ⁇ meable mould surface of which is composed of particles with varying particle size, the particle size being small in the part forming the mould surface of the mould and larger in an underlying supporting layer for this part.
• 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 which may contain adhesion-improving agents and by hardening the mould manufactured by such mixture by for instance heat treatment. Also wedging between the particles may be used to give the mould strength.
• a mould having at the bottom a basic part in which the composite particles are linked together by a real fusion compound whereas the particles in the rest of the mould are linked together by a hardening conglutinating compound.
• Such a mould is characterized by good strength which will also enable it to resist considerable working pressure. It is also within the scope of the invention to use a mould the mould surface of which is shaped with such strength that the mould may be used for the finishing pres ⁇ sing of a moulded element.
• Finishing pressing may not only be used for quick removal of water from the pulp layer de ⁇ posited on the mould surface, but also to achieve an espe ⁇ cially 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 be achieved by an appropriate choice of the size and distribution of the particles of which the permeable mould surface may be com ⁇ posed both to obtain favourable conditions for the fixing compound between the particles and for a suitable dimension- ing of the porosity in order to avoid an undesired pressure drop through a building material which is unnecessarily dense.
• 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 pro- **d 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 pro- cess, exposing for cleaning purposes the mould surface to an air current passing through the mould passages for a ga ⁇ seous medium.
• a mould used in accordance with the invention and con ⁇ structed by a particle composite material may be manufac- tured in such a way that it may after use or in case of wear be regenerated as the particle-shaped building material of the mould may be recycled.
• a starting material containing long fibres may be used which is processed to a pulp partly by means of a shake-out in a pulper, partly by a preceding, separate, controlled dry grinding by which the starting material is divided into dosage amounts and divided into-its fibres whereupon the object is manufactured from the pulp thus cre ⁇ ated.
• a pulper as an essential step in the proces ⁇ sing of the fibre raw materials for the creation of a pulp from which the desired objects are to be manufactured takes place among other things in cases where the fibre raw mate ⁇ rials 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 o- ther and is thereby divided and the raw materials separated into fibres.
• the method according to the invention achieves that to the pulper is at least partly added a fibre raw material the fibres of which are already to a substantial degree se- parated into single fibres why they are more instant and at the same time susceptible to the self-grinding effect and mixing effect obtained in the pulper.
• the pulper proces ⁇ ses a more uniform raw material also the grinding degree ob ⁇ tained in the pulper through self grinding may be adjusted to be more uniform and the above-mentioned binding of water in the pulp leaving the pulper will thus be more control ⁇ lable.
• Recycled paper waste exists in many different qualities and gradings. If this material prior to the shake-out in the pulper is exposed to a separate, controlled dry grinding, it is often possible to use a poorer and thus cheaper mate ⁇ rial quality, than if the division process was only carried out as a shake-out in the pulper. It lies within the scope of the invention to carry out the preceding separate dry grinding as mentioned above as a multiple-stage process whereby it is possible to separate the starting material in dosage amounts in a special effi ⁇ cient manner. In this particular way also e.g. waste paper material containing plastic, water resistant paper, plastic laminated cartons and paper, to the degree desired can 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 following production pro ⁇ cess.
• a long fibre starting material having been subjected to a separate controlled dry grinding be added to an already in the pulper formed pulp and be subjected to a joint time-limited shake-out with this.
• the separate, controlled dry grinding suggested accord- ing 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 objects to be manufactured must be shrink proof and measure proof.
• a starting material with a high content of wooden fibre causes less shrinkage that if the fibre were cellulose fibre. It has turned out that by applying the me ⁇ thod 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 mate ⁇ rial a pulp which causes no undesired shrinkage of the ob ⁇ jects manufactured.
• auxiliary materials such as filling material and chemicals and binding agents.
• the auxiliary materials decide whether the objects manufactured shall be more or less strong, hard or transpa ⁇ rent, or weak, soft and absorbing.
• the present invention is also advantageous in connection with the application of such auxiliary materials.
• auxiliary materials at different stages of the total ma/iu- facturing process.
• the achieved open structure of the final pulp obtained as a result of this particular invention, even facilitates a better access for auxiliary materials so that e.g. a binding material may be applied more or less in ⁇ tegrating on the surface of the objects in order to increase the weight.
• auxiliary material under the preceding separate, controlled dry grinding will in a espe- cially good manner be able to further a particular uniform distribution of the auxiliary materials in the manufactured fibre mass. It is of course also still possible to add the auxiliary materials to the pulper.
• the shake-out in the pulper is carried out as a manu ⁇ facturing process dependent on the preceding separate, con ⁇ trolled grinding.
• the obtained degree of self grinding in the pulper can be adjusted in accordance with the degree of the grinding which according to the circum- stances has been carried out at the preceding dry grinding stage(s) .
• a paper pulp which in the pulper " is separated into a normal, at self grinding obtained grin ⁇ ding degree of 60° SR (Schopper-Riegler) , 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.
• 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 ma ⁇ nufacturing objects with large wall thickness.
• Waste paper also called return paper
• Waste paper may be very com- posite, and contain fibre with a large variety of fibre lengths.
• the ave ⁇ rage fibre length is so large that the above mentioned ad ⁇ vantages especially as regards drainage and structure may be obtained when this paper material forms part-of the ma- nufacturing process.
• the method according to the invention will also be a- vailable for the processing of so-called virgin material.
• Fig. 1 diagrammatically shows a survey of process pro ⁇ ceedings summing up the proceeding phases which may take place during the proceeding of a process for the manufacture of for instance a pallet,
• Fig. 3 an inclined presentation of a first embodiment for a load-carrying element in the form of a pallet manufac ⁇ tured 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 pal ⁇ let.
• FIG. 6 schematic cross section through a fourth embo- diment for a pallet
• Fig. 7 inclined presentation of a fifth embodiment for a pallet.
• FIG. 8 schematic cross section through a sixth embo ⁇ diment for a pallet
• Fig. 9 schematic pallet with a tension rope.
• Fig. 10 schematic pallet with a wooden support rail.
• Fog. 11 schematic pallet with a support rail of fibre raw material.
• Fig. 12 schematic cross section through a pallet con- structed from elements of varying layer thickness.
• Fig. 14 a third embodiment for a pallet containing a single element of varying layer thickness.
• Fig. 15 a cross section through an embodiment for "the supporting legs of a pallet
• Fig. 16 schematic a mould with deposited element of fibre raw material, both the mould surface and thus also the deposited element having varying layer thickness.
• Example 2 15 Phase 1 up to and including phase 5 is carried out fol ⁇ lowed by phases 8 and 9 and finally phases 11 to 14 are car ⁇ ried out.
• One production line is used from phase 1 to phase 5 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 pro ⁇ duction line.
• the work is continued with usually several of
• the pallets are manufactured by means of the pro ⁇ cess according to the invention.
• 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.
• 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 nega ⁇ tive suction pressure used for depositing of the pulp on the foundation is controlled in such a way that a fibre raw ma-
• 10 terial layer is deposited on the foundation in such thick ⁇ ness that this in all essentials achieves the load capabi ⁇ lity desired for the element, i.e. in the present case the pallets.
• the water content of the applied pulp may be up to 75
• the pallets 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
• the invention comprises 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 ⁇ gether with similar products form part of another end pro-
• Fig. 3 shows schematically part of a pallet 10 designed with integrated legs and with strengthening ribs.
• Example a) 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 b) 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 substan ⁇ tially 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 c) 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 d the under side 16 of the pallet is designed with “wet” weight 7.5 kg and weight after drying 2.5 kg, and 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 e) The pallet has a three dimensional centre, part 26 with “wet” weight 6 kg and weight after drying 2 kg as well as two cover plates 28 each shaped on an even mould ⁇ 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- sembling of cover plates and legs 0.05 kg. Finished product weight: 6.95 kg.
• Fig. 7 shows a pallet, measurements 800 x 1200 x 150.
• Example f) The pallet is composed of two uniform, three dimensional plate elements 32 each having hollow pro ⁇ jections 34 projecting transversely to the plate part. The plate elements are mounted with their projections 34 point- ing 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 to 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 of these plates.
• Both the trapeze shaped and the even plates 36 and 40, 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 pos ⁇ sible to choose a larger og smaller number of plate layers which furthermore, owing to the pressing process, only re ⁇ sults in low drying costs.
• Example g) Two trapeze profiled fillers 36 with “wet” weight after moulding 4.5 kg, “wet” weight after pressing 3.0 kg and weight after drying 1.5 kg. Two even cover plates 40 with “wet” weight after moulding 4.5 kg, “wet” weight af ⁇ ter pressing 3.0 kg and weight after drying 1.5 kg. Nine legs (not shown) each with “wet” weight after moulding 0.3 kg and weight after drying 0.1 kg. Glue for assembling 0.05 kg.
• the plate parts and legs of the pallets may be shaped together in a joint suction opera ⁇ tion or they may be shaped in separate suction operations.
• the legs may also, where desired, be manufactured from an ⁇ other material than fibre raw material but experience has shown that by using the procedure according to the invention it is possible to manufacture legs with sufficient load capacity and robustness and at the same time low weight, as stated in the examples.
• 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.
• Figs. 9 to 11 show some examples of load-carrying e- lements in the form of pallets as a common support rail 44 of for example wood is placed, as for instance shown in Fig. 10, 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 mate ⁇ rial as the pallet's plate part 52.
• the invention's characteristic de ⁇ positing 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 ca ⁇ pability in the way that in the fibre raw material layer va ⁇ riations are made in the layer thickness, for instance as a coherent structural pattern.
• 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, «per- meable by the working medium, with a permeability varying in accordance with the desired variations in the layer thickness of the layer.
• Fig. 12 shows a cross section of a pallet constructed from two rib profiled interior elements 54 which on the out ⁇ side are covered by to even cover plates 56.
• Each interior element 54 has been manufactured in one single working pro- cess from a fibre raw material which is deposited on the mould surface of the suction mould with a wall thickness va ⁇ rying 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 of the rib formation is an- gular 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 pal ⁇ let 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 bot ⁇ toms 58b lie against exterior, even cover plates 60.
• 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 smal ⁇ lest 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 single active working process through suction of a fibre raw material as described. Also this element has varying layer thickness and it is thicker at the bottom 62b.
• Fig. 16 illustrates how such variations in the layer thickness may be achieved according to the invention.
• a mould 64 which at negative pres ⁇ sure 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- face 66.
• a mould with 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.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Paper (AREA)
• Pallets (AREA)
• Buffer Packaging (AREA)
• Dry Formation Of Fiberboard And The Like (AREA)

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• 1989
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• 1991
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