EP0406783B1 - Process for making hollow articles from lignocellulosic fibres - Google Patents

Process for making hollow articles from lignocellulosic fibres Download PDF

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Publication number
EP0406783B1
EP0406783B1 EP90112631A EP90112631A EP0406783B1 EP 0406783 B1 EP0406783 B1 EP 0406783B1 EP 90112631 A EP90112631 A EP 90112631A EP 90112631 A EP90112631 A EP 90112631A EP 0406783 B1 EP0406783 B1 EP 0406783B1
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Prior art keywords
mold
water
suspension
bonding agents
formed element
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German (de)
French (fr)
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EP0406783A3 (en
EP0406783A2 (en
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Eckhard Dipl.-Volkswirt Jagdt
Paul Dipl.-Ing. Buchholzer
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Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
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Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
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Priority claimed from DE19893922382 external-priority patent/DE3922382A1/en
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21J—FIBREBOARD; MANUFACTURE OF ARTICLES FROM CELLULOSIC FIBROUS SUSPENSIONS OR FROM PAPIER-MACHE
    • D21J3/00—Manufacture of articles by pressing wet fibre pulp, or papier-mâché, between moulds

Definitions

  • the invention relates to a method for producing molded parts with a spatial shape from lignocellulose-containing fibers according to the preamble of the main claim.
  • the production of molded parts with a spatial shape from lignocellulose-containing chips and fibers is preferably carried out in the pressing process using the required strengths, i.e. the spreading process is followed by the pressing process.
  • the strengths of the molded parts produced in this way are also sufficient for larger dimensions. These are mostly synthetic resin-bonded molded parts with a resin content of 4 to 20%. These molded parts are expensive. Environmentally harmful substances are emitted when such molded parts are burned. Both are disadvantageous.
  • a casting process is known, according to which molded parts are produced from fibers containing lignocellulose (porous fiberboard) without subsequent pressing.
  • the fiber suspension is placed in a casting box and the excess water is then expelled using a vacuum or gravity.
  • These panels have a strength which, due to the low material density, is not sufficient for a wide range of applications. If it is used to produce spatial molded parts of larger dimensions, in which heavy objects may also have to be transported, the strengths are not sufficient. If you want to achieve higher strengths, the walls and the bottom of such molded parts must have a disproportionately large wall thickness. This is disadvantageous, the applicability or usability of such molded parts is thereby limited.
  • the coffin industry relies on making coffins from solid wood, since the use of coffins from lignocellulose-containing chips and fibers has so far failed for the reasons mentioned above (no emission-free, high costs, insufficient strength).
  • a further production process for molded parts made of lignocellulose-containing fibers is known (VDI-Nachschreib (No. 32 / August 12, 1988).
  • An aqueous slurry of lignocellulose-containing material is then poured into a casting mold and the water is then sucked off with a vacuum.
  • the raw mass dries into With this procedure it is important that the resulting pressure drop acts evenly over the entire cross-section of the mold. If this is not done, a molded part with an uneven thickness and material density distribution is created.
  • nonwovens / fibreboards are used in the production Corresponding baffles are used. This possibility does not exist in the production of molded parts.
  • molded parts made of cast fiber according to the known method have inaccurate dimensions and uneven density distribution. This is disadvantageous.
  • the object of the invention is to provide a method for producing molded parts with spatial shaping from lignocellulose-containing fibers, according to which the molded part is easy to produce and has controllable strengths even with complicated profiling while maintaining uniform density distribution and dimensions.
  • the molded part By producing the molded part by the process according to the invention in such a way that the water-binder fiber suspension is introduced into a mold under pressure, it is achieved that a molded part with a uniform density distribution is produced both in the bottom section and in the walls. Even with molded parts with a complicated profile, a uniform density distribution can be achieved in the entire molded part.
  • a variable part with the desired strength is produced by the variable setting of the pressure and the negative pressure required to extract the excess water.
  • the application of pressure makes it possible to control the thickness of the floor and the walls. By introducing the suspension by pouring under pressure and simultaneously sucking off the excess water using a vacuum pump, much less vacuum is required than when pouring without pressure. This reduces the energy requirement.
  • the molded parts produced by casting with pressure application have no points which are not sufficiently compressed and thereby lower the strength of the molded part.
  • the fiber content of the suspension can be increased, so that the volume of the material to be introduced is significantly smaller than in the manufacturing process without pressure. Due to the application of pressure, the entire manufacturing process takes considerably less time than comparable processes without the application of pressure. In this way, the economy of the manufacturing process can be significantly increased.
  • smaller mold dimensions are required when the suspension is introduced under pressure than during the manufacturing process without applying pressure.
  • the bottom section of the molded part can be produced separately from the walls. This is particularly advantageous if e.g. the floor should have different strengths or material density than the walls. Furthermore, this method of producing the molded part in two steps is particularly advantageous when it concerns molded parts with a large floor area.
  • the procedure can be such that the suspension introduced into the mold is additionally mechanically compressed.
  • One way of carrying out the compression process is to lower a compression stamp into the mold.
  • the additional mechanical compression is always chosen when the molded parts to be manufactured are subject to particularly high demands in terms of strength and density.
  • the density of the moldings according to the invention is preferably 150 kg / m3 to 350 kg / m3.
  • the corresponding bending strength values are between 1.2 N / mm2. It can be determined by the fiber mass to be dosed and the choice of the pressure and vacuum to be used. This specified material density can be adhered to exactly by the method according to the invention.
  • a manufacturing method for molded parts with spatial shaping from lignocellulosic fibers in which the suspension introduced into a mold is compressed twice.
  • the individual compression processes are independent of each other; the first compression process serves to compress the bottom section of the molded part, the second compression process serves to compress the walls of the molded part to be produced.
  • the density of the walls and the bottom section can be the same or different.
  • the strengths of these two parts of the molded part can also be the same or different. This can be easily achieved by using the two-stage compression process.
  • the mechanical compression takes place by means of stamps which can be lowered into the mold.
  • the first punch which can be lowered into the mold and which serves to compress the bottom section is selected such that it also serves as a rough shape for the walls.
  • the variation of the thickness dimensions of the bottom section and the walls can be realized either by appropriate travel paths of the punches or by using different punches.
  • the former alternative is particularly inexpensive and simple in terms of device.
  • the water is expelled by gravity or vacuum.
  • the part is preferably dried at 180 ° C. In the case of parts with an average wall thickness of approximately 2 cm, the drying time is approximately one and a half to two hours. If the molded part remains in the outer or inner mold during the drying process, the convex wall deformations occurring in the direction of the molded part center due to the tensile stresses during drying are prevented.
  • the economy of the process according to the invention is significantly increased by the fact that the water-binder suspension is used in the recycling process.
  • the fiber suspension used to manufacture the molded parts can consist of 100% defibrator wood pulp with vegetable binders. It is advantageous if the binding and adhesive agent forms a neutral colloidal solution with water, at the same time performing the function of a suspending agent.
  • the molded parts produced by the process according to the invention have the advantages already described, such as uniform density distribution in the entire molded part, uniform strength in the entire molded part or uniform density and strength distribution only in the base section or only in the walls, i.e. a targeted reinforcement of a part of the molded part is possible.
  • the molded part has further stiffeners, the insertion of reinforcements on the bottom or side is not problematic in the manufacturing process.
  • the methods according to the invention are not limited to the production of molded parts of smaller dimensions. Molded parts can be produced which have a complicated profile and have a size of a few meters. This is possible because, due to the application of pressure or compression during the manufacturing process, much higher strengths of the molded part are achieved than when manufacturing without pressure and without compression. In addition, the strength of the molded part can be adjusted according to the requirements by varying the pressure and the negative pressure.
  • the processing of the finished molded part is possible as with solid wood.
  • the methods according to the invention can preferably be used for the production of molded parts for the coffin industry.
  • these processes are suitable for the production of molded parts for the packaging industry, gardening supplies or insulation purposes.
  • the mold for producing the molded parts consists of two parts, an inner and an outer mold. This advantageous design is particularly useful when the wall thickness or the base thickness of the molded part is to be varied while maintaining the external dimensions.
  • the outer shape advantageously has perforations on the bottom and on the sides. These allow a simple drainage process due to negative pressure or gravity.
  • a device which has a stamp which can be lowered from above into an outer mold perforated on the side and / or bottom. At the same time, this stamp has the function of limiting the filling space for the suspension.
  • a device which has an outer shape provided with bottom and side perforations and has a pouring plunger that can be lowered from above.
  • the casting ram compresses the bottom section and, in cooperation with the outer shape, represents a raw contour for the walls of the molded part.
  • a further ram that can be lowered into the outer shape is provided to compress the walls.
  • the device for carrying out the method has a casting box 1, consisting of a lower part 1 'and upper part 1' ', an outer mold 2 provided with perforations on the side and bottom and a compression ram 3.
  • feed channels 4 are provided for entering the suspension.
  • the process sequence is as follows: The suspension 5 is introduced through the channels 4 into the outer mold 2 under pressure. If the filling space 5 ', which is delimited by the walls of the outer mold 2 and the inner walls of the stamp 3, is filled with suspension, the stamp 3 is lowered and the supply of suspension is interrupted. At the same time, the excess water is expelled from the suspension 5 by means of negative pressure, which is facilitated by the perforations made in the outer mold 2. The molded part 6 thus produced is then dried at elevated temperature and heat treated.
  • the device has the following components: a mixer 7, a metering pump 8, an outer mold 10, which is attached in a casting box 9 and is perforated on the bottom and sides, a separator 11, a vacuum reservoir 12, a vacuum pump 13, a casting die 14, a pressing die 15, a separate, perforated inner mold 16 and a drying cabinet 17.
  • the procedure is as follows: A suspension in the mixer 7 is produced from the constituents water (A), fibers (B) and binder (C) with the addition of the expelled water with binder constituents (D). The suspension is poured into the perforated outer mold 10, which is inserted between the upper and lower part of the casting box 9.
  • the casting process is interrupted and the sedimentation of the fibers is waited until no more water flows out of the separator 11.
  • the casting die 14 is placed centrally in the outer mold 10, the cast fiber flow being compressed by its own weight and / or mechanical pressure.
  • the molding base 18 is produced by this process.
  • Molded walls 19 are then produced by pouring the suspension into the space between the outer contour of the die 14 and the inner contour of the outer mold 10 up to the height where the die 14 has the greatest width.
  • the sedimentation of the fibers is waited until no more water flows out of the separator 11.
  • the die 5 is now removed from the mold and the die 15 is retracted. Only the walls 19 of the molded part are compressed by the mechanical pressure.

Abstract

A process for making hollow articles from lignocellulosic fibres with vegetable binders is presented, by which it is possible to make articles (20) which have a uniform density distribution even in the case of complicated profiling. The dimensions of the articles (20) and their strength can be controlled by the production process presented. A specific setting of the density and of the strength in the article is possible by the process described. The features of the production process are: introducing the suspension into the mould under pressure and compressing the parts (18, 19) of the article. <IMAGE>

Description

Die Erfindung betrifft ein Verfahren zur Herstellung von Formteilen mit räumlicher Formgebung aus lignocellulosehaltigen Fasern gemäß dem Oberbegriff des Hauptanspruches.The invention relates to a method for producing molded parts with a spatial shape from lignocellulose-containing fibers according to the preamble of the main claim.

Die Herstellung von Formteilen mit räumlicher Formgebung aus lignocellulosehaltigen Spänen und Fasern erfolgt bei den geforderten Festigkeiten vorzugsweise im Preßverfahren, d.h. an den Streuvorgang schließt sich der Vorgang des Pressens an. Die Festigkeiten der so hergestellten Formteile reichen auch für größere Abmessungen. Es handelt sich dabei meistens um kunstharzgebundene Formteile mit Harzanteilen von 4 bis 20%. Diese Formteile sind teuer. Bei der Verbrennung solcher Formteile werden umweltbelastende Stoffe emittiert. Beides ist nachteilig.The production of molded parts with a spatial shape from lignocellulose-containing chips and fibers is preferably carried out in the pressing process using the required strengths, i.e. the spreading process is followed by the pressing process. The strengths of the molded parts produced in this way are also sufficient for larger dimensions. These are mostly synthetic resin-bonded molded parts with a resin content of 4 to 20%. These molded parts are expensive. Environmentally harmful substances are emitted when such molded parts are burned. Both are disadvantageous.

Daneben ist ein Gießverfahren bekannt, nach dem Formteile aus lignocellulosehaltigen Fasern (poröse Faserplatten) ohne anschließendes Pressen hergestellt werden. Dabei wird die Faser-Suspension in einen Gießkasten eingebracht und das überschüssige Wasser anschließend mittels Vakuum oder durch Schwerkraft ausgetrieben. Diese Platten weisen eine Festigkeit auf, die durch die geringe Materialdichte bedingt, nicht für eine breite Palette von Anwendungen ausreicht. Werden daraus räumliche Formteile von größeren Abmessungen hergestellt, in denen eventuell auch schwere Gegenstände transportiert werden müssen, reichen die Festigkeiten nicht aus. Will man höhere Festigkeiten erreichen, so müssen die Wandungen und der Boden solcher Formteile eine unverhältnismäßig große Wandstärke aufweisen. Dies ist nachteilig, die Anwendbarkeit, bzw. Verwendbarkeit solcher Formteile wird dadurch begrenzt. So ist z.B. die Sarg-Industrie darauf angewiesen, Särge aus Massivholz herzustellen, da die Verwendung von Särgen aus lignocellulosehaltigen Spänen und Fasern bisher aus den obengenannten Gründen (keine Emissionsfreiheit, hohe Kosten, nicht ausreichende Festigkeiten) scheiterte.In addition, a casting process is known, according to which molded parts are produced from fibers containing lignocellulose (porous fiberboard) without subsequent pressing. The fiber suspension is placed in a casting box and the excess water is then expelled using a vacuum or gravity. These panels have a strength which, due to the low material density, is not sufficient for a wide range of applications. If it is used to produce spatial molded parts of larger dimensions, in which heavy objects may also have to be transported, the strengths are not sufficient. If you want to achieve higher strengths, the walls and the bottom of such molded parts must have a disproportionately large wall thickness. This is disadvantageous, the applicability or usability of such molded parts is thereby limited. For example, the coffin industry relies on making coffins from solid wood, since the use of coffins from lignocellulose-containing chips and fibers has so far failed for the reasons mentioned above (no emission-free, high costs, insufficient strength).

Aus der US A -162 3731 ist eine Vorrichtung zur Herstellung von dünnwandigen Formteilen aus celluosehaltigem Material bekannt. Als Ausgangsmaterial wird hier Papierzellstoff verwendet. Da das Material sehr fein ist, sind für die Entwässerung des Materials bei der Herstellung von dünnwandigen Teilen hohe Kräfte notwendig. Während des Herstellungsprozesses wird das feine cellulosehaltige Material im unteren Absaugbereich so verdichtet, welches das überschüssige Material, welcher darüber gestaut ist, nicht abgesaugt werden kann. Deshalb müssen die aus diesem Material hergestellten Teile dünnwandig ausgestattet werden; dickwandige Teile können nach diesem Verfahren überhaupt nicht entwässert werden.From US A -162 3731 a device for the production of thin-walled molded parts from cellulose-containing material is known. Paper pulp is used as the starting material here. Since the material is very fine, high forces are required to drain the material when producing thin-walled parts. During the manufacturing process, the fine cellulose-containing material in the lower suction area is compressed so that the excess material that is stowed over it cannot be suctioned off. Therefore, the parts made from this material must be thin-walled; thick-walled parts cannot be dewatered at all using this method.

Es ist ein weiteres Herstellungsverfahren für Formteile aus lignocellulosehaltigen Fasern bekannt (VDI-Nachrichten (Nr. 32/ 12. August 1988). Danach wird ein wässriger Brei aus lignocellulosehaltigem Material in eine Gießform gegossen und das Wasser anschließend mit Vakuum abgesaugt. Die Rohmasse trocknet in einem Trockenkanal. Bei dieser Vorgehensweise ist es wichtig, daß das entstehende Druckgefälle gleichmäßig über den ganzen Querschnitt der Form wirkt. Geschieht dies nicht, so entsteht ein Formteil mit ungleichmäßiger Dicke und Materialdichteverteilung. Um dies zu vermeiden, werden bei der Herstellung von Vliesen/Faserplatten entsprechende Leitbleche eingesetzt. Bei Herstellung von Formteilen besteht diese Möglichkeit nicht. Somit weisen die nach dem bekannten Verfahren hergestellten Formteile aus Faserguß ungenaue Abmessungen und ungleiche Dichteverteilung auf. Dies ist nachteilig.A further production process for molded parts made of lignocellulose-containing fibers is known (VDI-Nachrichten (No. 32 / August 12, 1988). An aqueous slurry of lignocellulose-containing material is then poured into a casting mold and the water is then sucked off with a vacuum. The raw mass dries into With this procedure it is important that the resulting pressure drop acts evenly over the entire cross-section of the mold. If this is not done, a molded part with an uneven thickness and material density distribution is created. To avoid this, nonwovens / fibreboards are used in the production Corresponding baffles are used. This possibility does not exist in the production of molded parts. Thus, molded parts made of cast fiber according to the known method have inaccurate dimensions and uneven density distribution. This is disadvantageous.

Aufgabe der Erfindung ist es, ein Verfahren zur Herstellung von Formteilen mit räumlicher Formgebung aus lignocellulosehaltigen Fasern anzugeben nach dem das Formteil einfach herzustellen ist und auch bei einer komplizierten Profilierung unter Einhaltung gleichmäßiger Dichteverteilung und Abmessungen kontrollierbare Festigkeiten aufweist.The object of the invention is to provide a method for producing molded parts with spatial shaping from lignocellulose-containing fibers, according to which the molded part is easy to produce and has controllable strengths even with complicated profiling while maintaining uniform density distribution and dimensions.

Diese Aufgabe ist gemäß der Erfindung durch die kennzeichnenden Merkmale der Ansprüche 1 und 4 gelöst. Die Unteransprüche stellen vorteilhafte Weiterbildungen dar.This object is achieved according to the invention by the characterizing features of claims 1 and 4. The subclaims represent advantageous developments.

Durch die Herstellung des Formteiles nach dem erfindungsgemäßen Verfahren derart, daß die Wasser-Bindemittel-Faser-Suspension unter Druck in eine Form eingebracht wird, wird erreicht, daß ein Formteil mit gleichmäßiger Dichteverteilung sowohl im bodenseitigen Abschnitt als auch in den Wandungen entsteht. Auch bei Formteilen mit einer komplizierten Profilierung ist dadurch eine gleichmäßige Dichteverteilung im gesamten Formteil erreichbar. Durch die variable Einstellung des Druckes und des zum Absaugen des Überschußwassers notwendigen Unterdruckes wird ein Formteil mit gewünschter Festigkeit hergestellt. Des weiteren ist durch die Druckanwendung erreichbar, daß die Stärke des Bodens und der Wandungen kontrollierbar ist. Durch das Einbringen der Suspension durch Gießen unter Druck und gleichzeitiges Absaugen des Überschußwassers mittels einer Vakuumpumpe wird wesentlich weniger Vakuum benötigt, als beim Gießen ohne Druck. Somit sinkt der Energiebedarf. Die durch Gießen mit Druckanwendung hergestellten Formteile weisen keine Stellen auf, die nicht genügend verdichtet sind und dadurch die Festigkeit des Formteiles senken. Durch die Anwendung des Druckes kann der Faserstoffgehalt der Suspension erhöht werden, so daß das Volumen des einzubringenden Materials wesentlich kleiner ist als beim Herstellungsvorgang ohne Druck. Das gesamte Herstellungsverfahren dauert durch die Druckanwendung wesentlich kürzer als vergleichbare Verfahren ohne Druckanwendung. Die Wirtschaftlichkeit des Herstellungsprozesses kann auf diese Weise also wesentlich gesteigert werden. Außerdem werden bei gleichgroßen Formteilen bei Einbringen der Suspension unter Druck kleinere Formabmessungen benötigt als beim Herstellungsvorgang ohne Druckanwendung.By producing the molded part by the process according to the invention in such a way that the water-binder fiber suspension is introduced into a mold under pressure, it is achieved that a molded part with a uniform density distribution is produced both in the bottom section and in the walls. Even with molded parts with a complicated profile, a uniform density distribution can be achieved in the entire molded part. A variable part with the desired strength is produced by the variable setting of the pressure and the negative pressure required to extract the excess water. Furthermore, the application of pressure makes it possible to control the thickness of the floor and the walls. By introducing the suspension by pouring under pressure and simultaneously sucking off the excess water using a vacuum pump, much less vacuum is required than when pouring without pressure. This reduces the energy requirement. The molded parts produced by casting with pressure application have no points which are not sufficiently compressed and thereby lower the strength of the molded part. By applying the pressure, the fiber content of the suspension can be increased, so that the volume of the material to be introduced is significantly smaller than in the manufacturing process without pressure. Due to the application of pressure, the entire manufacturing process takes considerably less time than comparable processes without the application of pressure. In this way, the economy of the manufacturing process can be significantly increased. In addition, with molded parts of the same size, smaller mold dimensions are required when the suspension is introduced under pressure than during the manufacturing process without applying pressure.

Gemäß Lösungsvorschlag des Anspruches 2 wird erreicht, daß der bodenseitige Abschnitt des Formteiles getrennt von den Wandungen hergestellt werden kann. Dies ist besonders dann von Vorteil, wenn z.B. der Boden andere Festigkeiten bzw. Materialdichte aufweisen soll als die Wandungen. Weiterhin ist dieses Verfahren der Herstellung des Formteiles in zwei Schritten besonders dann vorteilhaft, wenn es sich um Formteile mit einer flächenmäßig großen Bodenausdehnung handelt.According to the proposed solution of claim 2 it is achieved that the bottom section of the molded part can be produced separately from the walls. This is particularly advantageous if e.g. the floor should have different strengths or material density than the walls. Furthermore, this method of producing the molded part in two steps is particularly advantageous when it concerns molded parts with a large floor area.

In Ausgestaltung des erfindungsgemäßen Herstellungsverfahrens kann so vorgegangen werden, daß die in die Form eingebrachte Suspension zusätzlich mechanisch verdichtet wird. Eine Möglichkeit der Ausführung des Verdichtungsvorganges ist das Absenken eines Verdichtungsstempels in die Form. Die zusätzliche mechanische Verdichtung wird immer dann gewählt, wenn an die herzustellenden Formteile besonders hohe Anforderungen bezüglich Festigkeit und Dichte gestellt werden.In an embodiment of the production method according to the invention, the procedure can be such that the suspension introduced into the mold is additionally mechanically compressed. One way of carrying out the compression process is to lower a compression stamp into the mold. The additional mechanical compression is always chosen when the molded parts to be manufactured are subject to particularly high demands in terms of strength and density.

Die Dichte der erfindungsgemäßen Formteile beträgt vorzugsweise 150 kg/m³ bis 350 kg/m³. Die entsprechenden Biegefestigkeitswerte liegen zwischen 1,2 N/mm². Sie kann durch die zu dosierende Fasermasse und die Wahl des anzuwendenden Druckes und Unterdruckes bestimmt werden. Diese vorgegebene Materialdichte kann nach dem erfindungsgemäßen Verfahren genau eingehalten werden.The density of the moldings according to the invention is preferably 150 kg / m³ to 350 kg / m³. The corresponding bending strength values are between 1.2 N / mm². It can be determined by the fiber mass to be dosed and the choice of the pressure and vacuum to be used. This specified material density can be adhered to exactly by the method according to the invention.

Gemäß dem Lösungsvorschlag des Anspruches 4 ist ein Herstellungsverfahren für Formteile mit räumlicher Formgebung aus lignocellulosehaltigen Fasern angegeben, bei dem die in eine Form eingebrachte Suspension zweimal verdichtet wird. Die einzelnen Verdichtungsvorgänge sind unabhängig voneinander; der erste Verdichtungsvorgang dient zur Verdichtung des bodenseitigen Abschnittes des Formteiles, der zweite Verdichtungsvorgang dient zur Verdichtung der Wandungen des herzustellenden Formteiles. Die Dichte der Wandungen und des bodenseitigen Abschnittes kann gleich oder unterschiedlich sein. Auch die Festigkeiten dieser beiden Teile des Formteiles können gleich oder unterschiedlich sein. Dies ist durch die Verwendung des zweistufigen Verdichtungsvorganges einfach erreichbar. Die mechanische Verdichtung erfolgt mittels in die Form absenkbarer Stempel. Dabei ist der erste in die Form absenkbare Stempel, welcher zur Verdichtung des bodenseitigen Abschnittes dient, so gewählt, daß er gleichzeitig als Rohform für die Wandungen dient. Die Variation der Dickenabmessungen des bodenseitigen Abschnittes und der Wandungen ist entweder durch entsprechende Verfahrwege der Stempel realisierbar oder durch Einsatz verschiedener Stempel. Die erstgenannte Alternative ist besonders kostengünstig und vorrichtungsmäßig einfach.According to the proposed solution of claim 4, a manufacturing method for molded parts with spatial shaping from lignocellulosic fibers is specified, in which the suspension introduced into a mold is compressed twice. The individual compression processes are independent of each other; the first compression process serves to compress the bottom section of the molded part, the second compression process serves to compress the walls of the molded part to be produced. The density of the walls and the bottom section can be the same or different. The strengths of these two parts of the molded part can also be the same or different. This can be easily achieved by using the two-stage compression process. The mechanical compression takes place by means of stamps which can be lowered into the mold. The first punch which can be lowered into the mold and which serves to compress the bottom section is selected such that it also serves as a rough shape for the walls. The variation of the thickness dimensions of the bottom section and the walls can be realized either by appropriate travel paths of the punches or by using different punches. The former alternative is particularly inexpensive and simple in terms of device.

Das Austreiben des Wassers findet statt durch Schwerkraft oder Vakuum.The water is expelled by gravity or vacuum.

Die Trocknung des Teiles findet vorzugsweise bei 180° C statt. Bei Teilen von einer mittleren Wandstärke von etwa 2cm beträgt die Trocknungszeit ca. eineinhalb bis zwei Stunden. Verbleibt das Formteil während des Trocknungsprozesses in der Außen- oder auf der Innenform, so werden die durch die Zugspannungen während der Trocknung auftretende konvexe Wandverformungen in Richtung Formteilmitte verhindert.The part is preferably dried at 180 ° C. In the case of parts with an average wall thickness of approximately 2 cm, the drying time is approximately one and a half to two hours. If the molded part remains in the outer or inner mold during the drying process, the convex wall deformations occurring in the direction of the molded part center due to the tensile stresses during drying are prevented.

Die Wirtschaftlichkeit des erfindungsgemäßen Verfahrens wird nicht zuletzt wesentlich dadurch gesteigert, daß die Wasser-Bindemittel-Suspension im Recyclingverfahren verwendet wird. Die zur Herstellung der Formteile verwendete Faser-Suspension kann aus 100% Defibrator-Holzfaserstoff mit pflanzlichen Bindemitteln bestehen. Es ist vorteilhaft, wenn das Binde- und Klebemittel mit Wasser eine neutrale kolloidale Lösung bildet, wobei zugleich die Funktion eines Suspendiermittels erfüllt wird.Last but not least, the economy of the process according to the invention is significantly increased by the fact that the water-binder suspension is used in the recycling process. The fiber suspension used to manufacture the molded parts can consist of 100% defibrator wood pulp with vegetable binders. It is advantageous if the binding and adhesive agent forms a neutral colloidal solution with water, at the same time performing the function of a suspending agent.

Die nach den erfindungsgemäßen Verfahren hergestellten Formteile weisen die bereits beschriebenen Vorteile auf, wie gleichmäßige Dichteverteilung im gesamten Formteil, gleichmäßige Festigkeit im gesamten Formteil oder gleichmäßige Dichte und Festigkeitsverteilung nur im Bodenabschnitt bzw. nur in den Wandungen, d.h. eine gezielte Verstärkung eines Teiles des Formteiles ist möglich.The molded parts produced by the process according to the invention have the advantages already described, such as uniform density distribution in the entire molded part, uniform strength in the entire molded part or uniform density and strength distribution only in the base section or only in the walls, i.e. a targeted reinforcement of a part of the molded part is possible.

Sollte das Formteil noch weitere Versteifungen aufweisen, so ist die Einlegung von bodenseitigen bzw. seitlichen Armierungen beim Herstellungsprozeß nicht problematisch.If the molded part has further stiffeners, the insertion of reinforcements on the bottom or side is not problematic in the manufacturing process.

Die erfindungsgemäßen Verfahren sind nicht auf Herstellung von Formteilen kleinerer Abmessungen beschränkt. Es können Formteile hergestellt werden, die eine komplizierte Profilierung aufweisen und eine Größenordnung von einigen Metern besitzen. Dies ist dadurch möglich, weil aufgrund der Druckanwendung bzw. der Verdichtung während des Herstellungsprozesses wesentlich höhere Festigkeiten des Formteiles erreicht werden als beim Herstellen ohne Druck und ohne Verdichtung. Außerdem kann die Festigkeit des Formteiles durch die Variation des Drucks und des Unterdruckes den Anforderungen entsprechend eingestellt werden.The methods according to the invention are not limited to the production of molded parts of smaller dimensions. Molded parts can be produced which have a complicated profile and have a size of a few meters. This is possible because, due to the application of pressure or compression during the manufacturing process, much higher strengths of the molded part are achieved than when manufacturing without pressure and without compression. In addition, the strength of the molded part can be adjusted according to the requirements by varying the pressure and the negative pressure.

Die Bearbeitung des fertigen Formteiles ist wie bei Massivholz möglich.The processing of the finished molded part is possible as with solid wood.

Die erfindungsgemäßen Verfahren können bevorzugt zur Herstellung von Formteilen für die Sargindustrie angewendet werden. Daneben eignen sich diese Verfahren zur Herstellung von Formteilen für die Verpackungsindustrie, dem Gärtnereibedarf oder Isolationszwecke.The methods according to the invention can preferably be used for the production of molded parts for the coffin industry. In addition, these processes are suitable for the production of molded parts for the packaging industry, gardening supplies or insulation purposes.

Die Form zur Herstellung der Formteile besteht aus zwei Teilen, einer Innen- und einer Außenform. Diese vorteilhafte Ausbildung kommt besonders dann zum Tragen, wenn unter Beibehaltung der äußeren Abmessungen, die Wanddicke bzw. die Bodendicke des Formteiles variiert werden soll. Die Außenform besitzt vorteilhaftenweise bodenseitige und seitliche Perforationen. Diese erlauben einen einfache Entwässerungsvorgang durch Unterdruck oder Schwerkraft.The mold for producing the molded parts consists of two parts, an inner and an outer mold. This advantageous design is particularly useful when the wall thickness or the base thickness of the molded part is to be varied while maintaining the external dimensions. The outer shape advantageously has perforations on the bottom and on the sides. These allow a simple drainage process due to negative pressure or gravity.

Zur Durchführung des Verfahrens nach Anspruch 3 ist eine Einrichtung notwendig, die einen Stempel aufweist, welcher von oben in eine seitlich und/oder bodenseitig perforierte Außerform absenkbar ist. Gleichzeitig hat dieser Stempel die Funktion der Begrenzung des Füllraumes für die Suspension.To carry out the method according to claim 3, a device is necessary which has a stamp which can be lowered from above into an outer mold perforated on the side and / or bottom. At the same time, this stamp has the function of limiting the filling space for the suspension.

Zur Durchführung des Verfahrens nach Anspruch 4 ist eine Einrichtung vorgesehen, die eine mit bodenseitigen und seitlichen Perforationen versehene Außenform und einen von oben in diese absenkbaren Gießstempel aufweist. Der Gießstempel verdichtet den bodenseitigen Abschnitt und stellt mit der Außenform zusammenwirkend eine Rohkontur für die Wandungen des Formteiles dar. Zur Verdichtung der Wandungen ist ein weiterer in die Außenform absenkbarer Stempel vorgesehen.To carry out the method according to claim 4, a device is provided which has an outer shape provided with bottom and side perforations and has a pouring plunger that can be lowered from above. The casting ram compresses the bottom section and, in cooperation with the outer shape, represents a raw contour for the walls of the molded part. A further ram that can be lowered into the outer shape is provided to compress the walls.

Ausführungsbeispiele der erfindungsgemäßen Verfahren sind in den nachfolgenden Zeichnungen dargestellt. Es zeigen:

Fig.1
Eine schematische Darstellung des Verfahrensablaufes beim Einbringen der Suspension unter Druck mit einer gleichzeitigen mechanischen Verdichtung.
Fig.2
Eine schematische Darstellung des Verfahrensablaufes bei Herstellung der Formteile mit zweimaliger Verdichtung.
Exemplary embodiments of the method according to the invention are shown in the following drawings. Show it:
Fig. 1
A schematic representation of the process flow when introducing the suspension under pressure with a simultaneous mechanical compression.
Fig. 2
A schematic representation of the process flow in the production of the molded parts with two compression.

Die Einrichtung zur Durchführung des Verfahrens weist einen Gießkasten 1, bestehend aus einem Unterteil 1' und Oberteil 1'', eine mit seitlichen und bodenseitigen Perforationen versehene Außenform 2 und einen Verdichtungsstempel 3 auf. An dem Gießkasten 1 sind Zufuhrkanäle 4 für die Eingabe der Suspension vorgesehen. Es ergibt sich folgender Verfahrensablauf: Die Suspension 5 wird durch die Kanäle 4 in die Außenform 2 unter Druck eingegeben. Ist der Füllraum 5', der durch die Wandungen der Außenform 2 und die Innenwandungen des Stempels 3 begrenzt ist, mit Suspension gefüllt, so wird der Stempel 3 abgesenkt, die Suspensionszufuhr wird unterbrochen. Gleichzeitig wird das überschüssige Wasser aus der Suspension 5 mittels Unterdruck ausgetrieben, was durch die in der Außenform 2 angebrachten Perforationen erleichtert wird. Das so hergestellte Formteil 6 wird anschließend bei erhöhter Temperatur getrocknet und wärmevergütet.The device for carrying out the method has a casting box 1, consisting of a lower part 1 'and upper part 1' ', an outer mold 2 provided with perforations on the side and bottom and a compression ram 3. On the casting box 1, feed channels 4 are provided for entering the suspension. The process sequence is as follows: The suspension 5 is introduced through the channels 4 into the outer mold 2 under pressure. If the filling space 5 ', which is delimited by the walls of the outer mold 2 and the inner walls of the stamp 3, is filled with suspension, the stamp 3 is lowered and the supply of suspension is interrupted. At the same time, the excess water is expelled from the suspension 5 by means of negative pressure, which is facilitated by the perforations made in the outer mold 2. The molded part 6 thus produced is then dried at elevated temperature and heat treated.

Zur Durchführung des in Fig. 2 dargestellten Verfahrensablaufes weist die Einrichtung folgende Bestandteile auf: Einen Mischer 7, eine Dosierpumpe 8, eine in einem Gießkasten 9 angebrachte, bodenseitig und seitlich perforierte Außenform 10, einen Abscheider 11, einen Vakuumvorratsbehälter 12, eine Vakuumpumpe 13, einen Gießstempel 14, einen Preßstempel 15, eine gesonderte, perforierte Innenform 16 und einen Trockenschrank 17 auf. Der Verfahrensablauf ist folgender: Aus den Bestandteilen Wasser (A), Fasern (B), und Bindemittel (C) unter Zugabe des ausgetriebenen Wassers mit Bindemittelanteilen (D) wird eine Suspension im Mischer 7 hergestellt. Die Suspension wird in die perforierte Außenform 10 gegossen, die zwischen das Ober- und Unterteil des Gießkastens 9 eingelegt ist. Nachdem die eingegebene Suspensionsmenge für den Bodenabschnitt ausreichend ist, wird der Gießvorgang unterbrochen und die Sedimentation der Fasern abgewartet, bis kein Wasser mehr aus dem Abscheider 11 fließt. Der Gießstempel 14 wird zentrisch in die Außenform 10 eingelegt, wobei durch sein Eigengewicht und/oder einen mechanischen Druck das gegossene Faserfließ verdichtet wird. Durch diesen Vorgang wird der Formteilboden 18 hergestellt. Anschließend werden Formteilwandungen 19 durch das Gießen der Suspension in den Zwischenraum zwischen der Außenkontur des Gießstempels 14 und der Innenkontur der Außenform 10 bis zu der Höhe, wo der Gießstempel 14 die größte Breite aufweist, hergestellt. Die Sedimentation der Fasern wird abgewartet, bis kein Wasser mehr aus dem Abscheider 11 fließt. Der Gießstempel 5 wird jetzt aus der Form herausgenommen und der Preßstempel 15 eingefahren. Durch den mechanischen Druck werden ausschließlich die Wandungen 19 des Formteiles verdichtet. Sobald der Preßstempel auf dem Gießkasten 9 aufliegt, wird Vakuum angelegt und das Formteil 20 durch Anlegung von Unterdruck entwässert. Hierdurch sinken die Faserrückstellkräfte des Formteiles 20, so daß am Ende des Herstellungsvorganges kein mechanischer Druck mehr erforderlich ist. Zu diesen, Zeitpunkt wird das Vakuum abgeschaltet und der Preßstempel 15 herausgenommen. Das Formteil 20 wird nochmals mittels Vakuum entwässert. Anschließend wird das Formteil 20 mit der Außenform 10 aus dem Gießkasten 9 herausgenommen und auf eine perforierte Innenform 16 aufgelegt. Die perforierte Außenform 10 kann nun zur Herstellung eines weiteren Formteiles eingesetzt werden. Auf der Innenform 16 aufgelegt, wird das Formteil 20 wärmevergütet.2, the device has the following components: a mixer 7, a metering pump 8, an outer mold 10, which is attached in a casting box 9 and is perforated on the bottom and sides, a separator 11, a vacuum reservoir 12, a vacuum pump 13, a casting die 14, a pressing die 15, a separate, perforated inner mold 16 and a drying cabinet 17. The procedure is as follows: A suspension in the mixer 7 is produced from the constituents water (A), fibers (B) and binder (C) with the addition of the expelled water with binder constituents (D). The suspension is poured into the perforated outer mold 10, which is inserted between the upper and lower part of the casting box 9. After the entered If the amount of suspension is sufficient for the bottom section, the casting process is interrupted and the sedimentation of the fibers is waited until no more water flows out of the separator 11. The casting die 14 is placed centrally in the outer mold 10, the cast fiber flow being compressed by its own weight and / or mechanical pressure. The molding base 18 is produced by this process. Molded walls 19 are then produced by pouring the suspension into the space between the outer contour of the die 14 and the inner contour of the outer mold 10 up to the height where the die 14 has the greatest width. The sedimentation of the fibers is waited until no more water flows out of the separator 11. The die 5 is now removed from the mold and the die 15 is retracted. Only the walls 19 of the molded part are compressed by the mechanical pressure. As soon as the press ram rests on the casting box 9, vacuum is applied and the molded part 20 is dewatered by applying negative pressure. As a result, the fiber restoring forces of the molded part 20 decrease, so that no mechanical pressure is required at the end of the manufacturing process. At this point in time, the vacuum is switched off and the press ram 15 is removed. The molded part 20 is dewatered again by means of a vacuum. The molded part 20 with the outer mold 10 is then removed from the casting box 9 and placed on a perforated inner mold 16. The perforated outer mold 10 can now be used to produce a further molded part. Placed on the inner mold 16, the molded part 20 is heat treated.

Claims (10)

  1. Method of producing thick-walled formed elements consisting of a bottom portion and one or several wall segments and presenting a small materials density with three-dimensional shaping of lignocellulose-bearing fibres with vegetable bonding agents, characterized in that a suspension of a water, bonding agents and fibers (5) is introduced under pressure into a mold (2), and that the water and the bonding agents bonded therein are largely expelled by means of vacuum whereupon the formed element (6) is dried and treated at a temperature of 180 °C approximately.
  2. Method according to claim 1, characterized in that first said suspension (5) for the bottom of the formed element is introduced under pressure into said mold (2) and that the water, inclusive of the bonding agent bonded therein, is largely expelled by means of vacuum, whereupon another suspension quantity for the walls is introduced under pressure into said mold and is dehydrated by vacuum, and that subsequently the formed element (6) is dried and treated at a temperature of 180 °C approximately.
  3. Method according to claim 1, characterized in that the suspension (5) introduced into said mold (2) is subjected to additional mechanical compression.
  4. Method of producing thick-walled formed elements consisting of a bottom segment and one or several wall segments and presenting a small materials density with three-dimensional shaping of lignocellulose-bearing fibres with vegetable bonding agents, characterized in that a suspension of a water, bonding agents and fibers (5) is introduced under pressure into a mold (10) and that, following the expulsion of water, the introduced quantity, which is sufficient approximately for producing the bottom-side segment (18), is subjected to mechanical compression, and that subsequently another quantity of suspension, which is sufficient for producing the wall segments (19), is introduced into said mold (10) and, following the expulsion of the water, is subjected to mechanical compression, and and that the excess water is expelled from the entire formed element (20) by vacuum, whereupon whereupon the formed element (20) is dried and treated.
  5. Method according to claim 3 or 4, characterized in that the mechanical compression is carried out by means of rams (3, 14, 15) adapted to be lowered into said mold (2, 10).
  6. Method according to one or several of claims 1 to 5, characterized in that the expelled water, inclusive of the bonding agents (D) bonded therein, is used for a water/bonding agent suspension (A, B, C, D) to be freshly produced.
  7. Thick-walled formed element with three-dimensional shaping and a small materials density, consisting of lignocellulose-bearing fibers, preferably 100% defibrator wood-fiber material, with vegetable bonding agents, in particular starch and/or methyl cellulose, realizable by introducing, under pressure, a suspension (5) of water, bonding agents, fibers into a mold (2), expelling the water and the bonding agents bonded therein from said suspension by means of vacuum, and by subsequently drying and heat-treating said formed element (6) at a temperature of 180°C approximately.
  8. Thick-walled formed element with three-dimensional shaping and a small materials density, consisting of a bottom-side segment and one or several wall segments of lignocellulose-bearing fibers with vegetable bonding agents, realizable by introducing, under pressure, a suspension (5) of water, bonding agents, fibers into a mold (2), in a quantity sufficient for producing the bottom-side segment (18), by expelling the water from said suspension, by mechanically compressing same, by introducing another quantity of suspension into said mold in a quantity sufficient for producing the wall segments (19), by expelling the water, by mechanically compressing said wall segments (19), by expelling the water from the entire formed element (20) by means of vacuum, and by subsequent treatment and drying.
  9. Device for carrying out the method according to Claim 3, characterized in that said mold comprises an outside mold (2) at the bottom side with lateral perforations, and a ram (3) adapted to be lowered from above into said mold and constituting a definition of the charging space (5) of said mold.
  10. Device for carrying out the method according to Claim 4, characterized in that an outside mold (10) at the bottom side and having lateral perforations, as well as a casting ram (14) are provided, with the latter being adapted to be lowered from above into said mold, and that between the walls of said outside mold (10) and those of said casting ram (14) a space is provided which conforms to the contour of the rough shape of said walls (19) of said formed element (20), and that another ram (15) is provided which is adapted to be lowered from above into said outside mold (10) and which has a contour so selected that the space between its walls and those of said outside mold (10) corresponds to the final shape of said formed element (20).
EP90112631A 1989-07-07 1990-07-03 Process for making hollow articles from lignocellulosic fibres Expired - Lifetime EP0406783B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE19893922382 DE3922382A1 (en) 1989-07-07 1989-07-07 Wood fibre moulding
DE3922382 1989-07-07
DE8910860U 1989-09-12
DE8910860U DE8910860U1 (en) 1989-07-07 1989-09-12

Publications (3)

Publication Number Publication Date
EP0406783A2 EP0406783A2 (en) 1991-01-09
EP0406783A3 EP0406783A3 (en) 1991-09-04
EP0406783B1 true EP0406783B1 (en) 1995-05-24

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EP90112631A Expired - Lifetime EP0406783B1 (en) 1989-07-07 1990-07-03 Process for making hollow articles from lignocellulosic fibres

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EP (1) EP0406783B1 (en)
AT (1) ATE123094T1 (en)
DE (2) DE8910860U1 (en)

Cited By (1)

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Publication number Priority date Publication date Assignee Title
WO2005012640A1 (en) * 2003-08-01 2005-02-10 Ecologico Packaging Sdn Bhd Device and manufacturing process for forming articles from plant fibre

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Publication number Priority date Publication date Assignee Title
EP0466653B1 (en) * 1990-07-11 1995-03-01 Alois Koch Procedure for manufacture of a coffin from formed pulp material
DE4330151A1 (en) * 1993-09-07 1995-03-09 Markus Brink Coffin for cremations and burials made of mechanical wood pulp fibre - a material recovered from 100% recycling paper - or similar materials (cellulose), including material-related carrying technique
FR2711998A1 (en) * 1993-11-04 1995-05-12 Chanard Alain Process for recycling waste paper for an ecological and economical insulating objective
DE19508434A1 (en) * 1995-03-09 1996-09-12 Duerener Sargfabrik Jacobs Kli Coffin made using natural fibers and process for its manufacture
NL1001959C2 (en) * 1995-12-21 1997-06-24 Univ Delft Tech Processing waste flower bulb for cardboard material using adhesive
GB9722547D0 (en) * 1997-10-25 1997-12-24 Pinco 976 Limited Improvements relating to forming machines
US6210531B1 (en) 1998-10-26 2001-04-03 Px Technologies, Ltd. Forming machines
US7074302B2 (en) * 2003-12-05 2006-07-11 Sonoco Development, Inc. Apparatus and process for forming three-dimensional fibrous panels

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GB261529A (en) * 1925-10-19 1926-11-25 Richard Ellis Hall Improvements in or relating to the manufacture of reinforced hollow ware articles or containers made from fibrous material
US1623731A (en) * 1926-04-02 1927-04-05 Hutchens Edward Pulp-forming press
CH183698A (en) * 1935-07-04 1936-04-30 Yngve Hedqvist Oskar Device for the production of box-like objects from a mass which contains fibers suspended in water.
DE879354C (en) * 1942-06-24 1953-06-11 Norddeutsche Homogenholz Ges M Process for the production of molded fibrous bodies
DE855196C (en) * 1945-04-14 1952-11-10 Norddeutsche Homogenholz Ges M Process and device for the production of molded fibrous bodies
US4034447A (en) * 1975-10-02 1977-07-12 Idra Ag Papier-mache coffin

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005012640A1 (en) * 2003-08-01 2005-02-10 Ecologico Packaging Sdn Bhd Device and manufacturing process for forming articles from plant fibre

Also Published As

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EP0406783A3 (en) 1991-09-04
DE59009115D1 (en) 1995-06-29
EP0406783A2 (en) 1991-01-09
ATE123094T1 (en) 1995-06-15
DE8910860U1 (en) 1990-11-08

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