Patent Application
20250034816
Embodiments described herein relate to a mold body for a pre-pressing tool for pressing three-dimensional preforms made of a fiber-containing material and a pre-pressing station with a pre-pressing tool with at least one mold body.
Fiber-containing materials are increasingly used, for example, to produce packaging for food (e.g., trays, capsules, boxes, etc.) and consumer goods (e.g., electronic devices, etc.) as well as beverage containers. Everyday items, such as disposable cutlery and tableware, are also made from fiber-containing material. Fiber-containing materials contain natural fibers or artificial fibers. Recently, fiber-containing material is increasingly used that has or is made of natural fibers which can be obtained, for example, from renewable raw materials or waste paper. The natural fibers are mixed in a so-called pulp with water and optionally further additives, such as starch. Additives can also have an effect on color, barrier properties and mechanical properties. This pulp can have a proportion of natural fibers of, for example, 0.1 to 10 wt. %. The proportion of natural fibers varies depending on the method used for the production of packaging etc. and the product properties of the product to be produced.
The production of fiber-containing products from a pulp generally takes place in a plurality of work steps. For this purpose, a fiber processing device has a plurality of stations or forming stations. In a forming station, for example, fibers can be suctioned in a cavity of a suction tool, thus forming a preform. For this purpose, the pulp is provided in a pulp supply, and the suction tool is at least partially immersed in the pulp with at least one suction cavity whose geometry essentially corresponds to the product to be manufactured. During the immersion, suction takes place via openings in the suction cavity, which are connected to a corresponding suction device, wherein fibers from the pulp accumulate on the surface of the suction cavity. The suctioned fibers or a preform can subsequently be brought into a pre-pressing tool via the suction tool, and the preform is pre-pressed. For this purpose, for example, it is possible to use elastic mold bodies which are inflated in order to press and, in the process, exert pressure on the preforms. During this pre-pressing process, the fibers in the preform are compressed and the water content of the preform is reduced. Alternatively, preforms can be provided by means of scooping, wherein a scoop tool is immersed in the pulp and during startup fibers are deposited on molded parts of the scoop tool.
After this, preforms are pressed in a hot pressing device to form finished molded parts. In this process, preforms are inserted into a hot press tool which has, for example, a lower tool half and an upper tool half which are heated. In the hot press tool, the preforms are pressed in a cavity under heat input, with residual moisture being removed by the pressure and heat so that the moisture content of the preforms is reduced from about 60 wt. % before hot pressing to, for example, 5-10 wt. % after hot pressing. The steam produced during hot pressing is suctioned off during the hot pressing via openings in the cavities and channels in the hot press tool.
However, a disadvantage of the known devices for pre-pressing is that the elastic mold bodies are deformed only insufficiently and to different degrees over the geometry of preforms, such that pre-pressed preforms have different wall thicknesses and different moisture content. In addition, this leads to such preforms remaining adhering to the pre-pressing tool or suction tool and/or tearing. Furthermore, in the case of preforms with sections that are moist to different degrees, damage also occurs in a subsequent hot pressing process, since these sections dry at different rates.
Elastic mold bodies also require a support structure so that the mold bodies cannot collapse. However, due to the necessary support structures, the elastic material can be “inflated” only to an inadequate extent so that a uniform pressure cannot be applied over the entire surface of the preforms to be pressed. This therefore results in pre-pressed sections in preforms pressed to a different extent that have different wall thicknesses and/or moisture contents, which leads to damage and destruction of the (pre-) forms in subsequent processes (e.g. hot pressing) as well as a lengthening of cycle times (e.g. pressing time) and an increase in the tool temperature (e.g. hot pressing tool).
By way of contrast, an object is to provide a solution that eliminates the above problems and allows improved pre-pressing of fiber-containing preforms with a high water content, in which mold bodies for pre-pressing tools and pre-pressing tools are simply designed, and the costs relating to servicing, maintenance and operation are reduced. Another object is to provide an alternative to the devices known from the prior art for pre-pressing preforms made of a fiber-containing material
The above-mentioned object is achieved by a mold body for a pre-pressing tool for pressing three-dimensional preforms made of a fiber-containing material, wherein the mold body includes a deformable material and has a shell which substantially reproduces a geometry of a preform to be pressed, wherein the mold body has at least one support structure formed integrally with the shell and made of deformable material.
The integral formation of the support structure together with the shell makes it possible to provide inherent rigidity for the mold body without an additional rigid support structure, which in the prior art has so far been formed from a metal block, wherein such a metal block additionally has bores in order to form channels for supplying a medium, which medium is used to “inflate” the mold body so that the pressing effect on the fiber-containing material of a preform can be provided.
The deformable material can be an elastic, flexible material which is deformable and fundamentally tends to return to its original shape after deformation. Various materials can be used for this purpose, which is tailored to the substances and fiber-containing materials to which the material is exposed.
Depending on the design of the at least one support structure made of a deformable material, such a support structure can significantly influence the behavior or deformation (deformation behavior) so that a uniform pressure can be provided on a preform over the entire surface of the shell so that, after pre-pressing, the preform has a substantially uniform moisture content and a defined wall thickness. For this purpose, the support structure can, for example, have strut-like connecting strands which are connected, for example, to oppositely situated inner surfaces of the shell, wherein the deformation of the shell is influenced upon introducing a medium because the connecting strands counteract a deformation. Since the connecting strands, like the shell, are made of a flexible material, they can be deformed, in particular stretched, when pressure prevails in the interior of the shell, e.g. due to the introduction of a medium. However, the connecting strands counteract a deformation of the shell so that as a result, less deformation of the shell occurs in the section of connection points between the connecting strands and the inside of the shell than in sections of the shell which are not connected to connecting strands or whose distance from such connection points is greater. This makes it possible to exert a targeted influence on the deformability of the shell by mold bodies by designing and arranging support structures integrally formed with the shell.
The integral formation of at least one support structure with the shell enables the provision of inherent rigidity, for example via a plurality of connecting strands, without the shell collapsing or being negatively deformed under pressure from the outside, i.e. being pressed inwards by “inflating” against the intended direction of shape. In this case, a plurality of connecting strands can be arranged in such a way that external pressure is always counteracted by at least one internal connection via at least one connecting strand of the at least one support structure. In summary, by appropriately designing a support structure (e.g. in a tree-like manner with a plurality of branches, which themselves have further branches that are connected to the inside of the shell), any external influence due to the support structure can be counteracted by a force. Within the scope of the technical teaching disclosed herein, embodiments are thus included in which the shell can be pressed in locally by a small amount by external pressure, but automatically returns to its initial shape immediately after the application of pressure. This is achieved in particular by the deformable material of the support structure (and the shell), which is elastic.
Such a mold body can be produced, for example, in an additive manufacturing process, wherein very delicate designs of support structures can be produced using 3D printing, for example, which are integrally connected to the inside of the shell so that an optimized expansion of the shell can be provided. In particular, production in an additive manufacturing process enables adaptation to the actually required wall thicknesses, diameters and directions of action without compromise. In summary, this makes it possible to produce a mold body with a support structure that is precisely adapted to the requirements (e.g. shape behavior).
Furthermore, such a mold body already has a receptacle space for a medium which provides a deformation.
In further embodiments, connecting strands can have at their end a plurality of thread-like connecting threads that are thinner compared to a middle section, which extend over a relatively large area and are thus connected to the inside of the shell over a larger section so that the expansion of the deformable material can be additionally influenced and controlled.
In further embodiments, the deformable material of the at least one support structure and the deformable material of the shell can differ in terms of their elasticity, wherein the deformation behavior of the mold body, in particular of the shell, can be further influenced in this way.
In further embodiments, the shell can have at least one elevation on an outer surface used for pressing. The elevation can be used to press fiber-containing material, especially in transitions, e.g. a transition between a floor surface of a fiber-containing preform and a side wall, wherein no material accumulations of the fiber-containing material occurs in the section of the transition after the pre-pressing. It can also be used to create depressions in a fiber-containing material during the pre-pressing.
In further embodiments, the shell can have a greater wall thickness in a section of the at least one elevation compared to sections of the shell not having at least one elevation on the outer surface. This allows compression to be achieved in a targeted manner in these reinforced sections, which results from the formation of the elevation and not only from the expansion of the deformable material of the shell. The elevation can be pressed on its outside into a groove or depression (e.g. into a transition), wherein the inside of the shell in the section of the elevation is deformed to the same extent as adjacent sections without elevation. However, the elevation allows a targeted displacement of an outer surface of the shell into a depression, for which purpose the wall thickness of the shell in the section of the elevation is increased by the thickness (height) of the elevation. This is also advantageous for example in transitions as described above, because it does not lead to excessive material displacement and/or compression under excessive pressure, which could ultimately result in a location that is made too thin.
In other embodiments, the shell can be deformed to varying degrees depending on the wall thickness of the shell. This allows, on the one hand, specific sections of the preform to be pressed more or less strongly and, on the other hand, a constant pressure force to be set over the entire surface or a definable section of the preform when the shell is deformed during pre-pressing.
In further embodiments, the at least one support structure can have an open-pored structure and/or at least one hollow space, at least sectionally. An open-pored structure and a hollow space can weaken sections of the at least one support structure so that, for example, with the same diameter or cross-section, they are more easily deformable or more elastic than sections without an open-pored structure or hollow space. Hollow spaces can be formed in different ways and can be, for example, elongated, drop-shaped, or spherical.
In further embodiments, the shell can be perforated at least sectionally. As a result of the perforated design, a medium introduced for deformation (e.g. gas or a gas mixture, such as compressed or ambient air), which primarily presses a preform via the elastic shell against a corresponding wall of a cavity during prepressing in a pre-pressing tool, can additionally penetrate a moist preform and in the process support dewatering during pressing. Furthermore, excessively high pressure can thus be prevented, such that the elastic mold body can be deformed more uniformly. As a result, preforms can be drained better because the air flow through the preform, by its saturation, removes additional water.
In further embodiments, the at least one support structure can have at least one strut which is connected to the shell at at least a first end. Such a strut can for example be designed as a connecting strand, as described above.
In further embodiments, the at least one support structure can have at least one second end that can be connected to a pre-pressing tool. For example, the at least one support structure can be connected to a tool holder for a mold body of a tool plate, wherein the tool plate provides a counter-support during deformation.
In further embodiments, the at least one support structure can have a plurality of struts, wherein the elasticity and deformation behavior of the shell can be determined according to a position of the ends. The struts can be designed as described above, wherein the struts can also have connecting strands which have a tree-like structure with a plurality of branches.
In further embodiments, the mold body can have a connection section for a pre-pressing tool in which an integrated connection unit is arranged. Mold bodies can be detachably connected to a tool holder of a pre-pressing tool or connected to a tool holder via a connection section and a connection unit so that an exchange can occur for maintenance purposes, when changing products, etc.
The connection section is the location at which the mold body is connected to a pre-pressing tool and can be connected to a tool part via the connection unit. The mold body can be connected or connectable, for example to a tool component of a pre-pressing tool, for example a tool plate, via the connection unit. An integrated design of the mold body includes, for example, embodiments in which the connection unit is completely or almost completely surrounded by the flexible material of the mold body. High loads occur in the connection section during closing for the pressing of preforms so that sufficient rigidity, which also counteracts damage, is provided by means of a stronger design. In addition, a pre-pressing of preforms in an edge section can thereby take place. For this purpose, a sufficiently stable pressing surface, or a press-mating surface relative to a further tool, is provided by a stronger wall thickness and overall stronger design, which can be reinforced by at least one insert made of metal (e.g., the connection unit). The ability to replace a mold body via the connection unit enable a tool change and maintenance without e.g. a tool plate having a plurality of mold bodies as a whole having to be replaced or serviced.
In further embodiments, the at least one support structure can have an integrated connection unit for a connection to a pre-pressing tool.
In further embodiments, the shell and the at least one support structure can be connected to a common connection unit or can have a common connection unit.
In further embodiments, the shell can be closed in a connection section, wherein the connection section has at least one connector for introducing a medium. Such mold bodies with integrated support structures can be produced in particular by additive manufacturing processes, since internal structures can also be manufactured in essentially closed mold bodies.
In addition, the connection unit can include a metal or a metal alloy or can comprise such. In further embodiments, the connection unit can have at least one connection element, wherein the at least one connection element can be or have a groove, a threaded hole, a pin, a screw, or a latching opening. In further embodiments, the connection section of the mold body can extend for a pre-pressing tool in an edge section for a preform. In further embodiments, the mold body can have a substantially identical wall thickness in wall and floor sections of three-dimensional preforms. In further embodiments, the mold body can include silicone or thermoplastic elastomers, in particular thermoplastic polyurethanes (TPU), or can comprise silicone or thermoplastic elastomers. The materials named above have proven to be advantageous as material for pre-pressing since they can be used within a wide temperature range and, depending on the mixture and design, are sufficiently flexible but at the same time sufficiently withstand pressure for pre-pressing.
In further embodiments, the shell and/or the support structure can have a reinforcement. A reinforcement can for example serve to press the shell at least radially outwards. Such a reinforcement can be formed by the deformable, elastic material of the shell or the support structure, wherein the elastic material of the reinforcement is more poorly deformable than, for example, the shell so that an outward-directed force always acts on the shell via the reinforcement so that the shell retains its shape. For example for this purpose, the reinforcement can be helical and located on the inner wall of the shell. In further embodiments, the reinforcement can also be formed by a wire or the like that is integrated into the shell so that the shell holds itself in position and shape. By being integrated into the shell, the wire is also protected from the outside and is not attacked by moisture or gases. In further embodiments, a reinforcement can be achieved by fibers that are embedded in the elastic material. Such fibers can be, for example, aramid, glass, or carbon fibers. This allows the mechanical properties (e.g. the modulus of elasticity) of the deformable, elastic material to be altered, for example to make the material more resistant or less deformable, or to prevent or counteract damage to the material.
The above-mentioned object is also achieved by a pre-pressing station with a pre-pressing tool which has at least one first tool component with at least one tool holder for a mold body and at least one mold body for pressing three-dimensional preforms made of a fiber-containing material according to one of the embodiments described above, and with at least one second tool component which has at least one cavity for receiving preforms, wherein in the closed state of the pre-pressing station, a mold cavity for pressing preforms is formed between an outer surface of a shell of the mold body and an inner wall of the cavity, and wherein the at least one mold body is connected to the tool holder via at least one support structure formed integrally with the shell and a connection section of the shell.
By forming the mold body with an integral support structure made of a deformable material, in particular elastic material, on the one hand, support structures for mold bodies can be dispensed with and, on the other hand, an adjustable offset, i.e. distance between the surface of the shell and the inner wall of the cavity (molding surface), can be achieved during pressing when the mold body is deformed or the shell is pressed against a fiber-containing material in the cavity by a medium.
In further embodiments, the outer surface of the shell can have a shape that is substantially adapted to the surface profile of the inner wall of the cavity.
In further embodiments, the outer surface of the shell can have at least one elevation which is associated with a transition and/or a depression in the inner wall of the cavity so that a substantially uniform pressing of the fiber-containing material of a preform can also be achieved in such sections of the cavity so that the preform has a uniform wall thickness and/or moisture content after pressing.
In further embodiments, the mold body can have an integrated connection unit for connection to the tool holder in the connection section and/or in the at least one support structure.
In further embodiments, the first tool component can have at least one channel through which a gas or gas mixture can be introduced into the shell of the mold body in order to deform the shell and to press a preform introduced into the mold space against the inner wall of the cavity via the outer surface of the shell.
In further embodiments, the wall thickness of the deformable material of the shell and the arrangement of the at least one support structure can be designed according to a geometry of a preform to be pressed so that, during the pre-pressing between the outer surface of the shell of the mold body and the inner wall of the cavity in the closed state of the pre-pressing station, a substantially uniform pressure on the preform can be generated over the entire surface of the shell.
In further embodiments, in a non-deformed state of the mold body, in particular the shell, the distance between the surface of the shell and the inner wall of the cavity can be different in size, wherein a substantially uniform pressure over the entire surface of a preform by the shell is also achieved by the formation and connection of the support structure to the shell.
In further embodiments, the at least one cavity can have openings for draining water that escapes from preforms during a pre-pressing process.
Another object of the present disclosure is to provide a manufacturing method for environmentally-friendly formed parts made of natural fibers and a corresponding machine with which these products (formed parts) can be produced effectively, flexibly and with good quality in a reproducible manner.
According to a first aspect of the present disclosure, an object is achieved by a molding station for a fiber-forming system for molding a formed part made from environmentally-friendly-degradable fiber material in a fiber-forming process, comprising
The term “environmentally-friendly-degradable fiber material” refers to fiber materials that can be decomposed by environmental factors such as moisture, temperature and/or light, with the decomposition process taking place in the short term, for example, in the range of days, weeks or a few months. For the sake of simplicity, the “environmentally-friendly-degradable fiber material” is below sometimes simply referred as “fiber material”. Preferably, neither the fiber material nor the decomposition products should pose an environmental hazard or contamination. Fiber materials, which in the context of the present disclosure represent an environmentally-friendly-degradable fiber material, are, for example, natural fibers obtained from cellulose, paper, cardboard, wood, grass, plant fibers, sugar cane residues, hemp, etc. or from their components or parts thereof and/or correspondingly recycled material. However, environmentally-friendly-degradable fiber material can also refer to artificially produced fibers such as PLA (polylactide), etc., which correspond to the above fiber materials or have their properties. The environmentally-friendly-degradable fiber material is preferably compostable. The environmentally-friendly-degradable fiber material and the containers made from it are preferably suitable for introduction into the material cycle of the German organic compost bin and as a resource for biogas plants. The fiber materials and the containers made from them are preferably biodegradable in accordance with EU standard EN 13432.
The term “pulp” refers to fluid masses that contain fibers, here the environmentally-friendly-degradable fiber material. The term “liquid” refers here to the state of aggregation of the pulp, the liquid pulp comprising the environmentally-friendly-degradable fiber material in the form of fibers (liquid solution with the environmentally-friendly-degradable fiber material). The fibers can be present as individual fibers, as a fiber structure or as a fiber group composed of a number of connected fibers. The fibers represent the fiber material, regardless of whether they are in the pulp as individual fibers, as a fiber structure or as a group of fibers. The fibers are dissolved in the liquid solution in such a way that they float in the liquid solution as much as possible with the same concentration, regardless of location, for example, as a mixture or suspension of liquid solution and fiber material. For this purpose, for example, the pulp can be appropriately tempered and/or circulated in some embodiments. The pulp preferably has a low consistency, i.e., a proportion of fiber material of less than 8%. In one embodiment, a pulp with a proportion of environmentally-friendly, degradable fiber material of less than 5%, preferably less than 2%, particularly preferably between 0.5% and 1.0%, is used in the method described herein. This small proportion of fiber material can, among other things, prevent clumping of the fiber material in the liquid solution, so that the fiber material can still be molded onto the suction tool with good quality. Clumped fiber material can be sucked in by the suction tool, but would probably result in a formed part with a fluctuating layer thickness, which should be avoided in the production of the formed parts, if possible. In this respect, the proportion of fiber material in the pulp should be small enough so that clumping or chaining does not occur or occurs only to a negligible extent. The liquid solution can be any solution suitable for the fiber-forming process. For example, the pulp can be an aqueous solution containing the environmentally-friendly, degradable fiber material. An aqueous solution is, among other things, an easy-to-handle solution.
The fiber-forming process refers to the process steps that are involved in forming the formed part, beginning with providing the pulp, molding the formed part from the fiber material from the pulp in the molding station, preforming the formed part in the preforming station, hot-pressing the formed part in the hot-pressing station and optionally coating the formed part with functional coatings, wherein the coating can be arranged at any point in the fiber-forming process that is suitable for the respective coating to be applied.
The formed parts can have any shape, also referred to here as a contour, provided this shape (or contour) can be produced in the method described herein or the method is suitable for producing this shape (or contour). The components used for the fiber-forming process can be adapted to the respective shape (or contour) of the formed part. In the case of different formed parts with different shapes (or contours), different correspondingly adapted components such as the suction tool, the suction head, the prepressing station, the hot-pressing station, etc. can be used. The target contour of the formed part and thus the corresponding shaping components is preferably designed in such a way that all surfaces of the formed part have an angle α of at least 3 degrees to the pressing direction during hot-pressing. For example, a surface perpendicular to the pressing direction (maximum pressure) has an angle α=90 degrees. This ensures that the hot-pressing pressure can be applied to all surfaces of the formed part. No pressure can be applied to surfaces parallel to the direction of pressure during hot-pressing. Final-shaped formed parts can represent a wide variety of products, for example, cups, containers, vessels, lids, bowls, portion containers, casings or containers for a wide variety of purposes.
The suction tool refers here to the tool in which the suction head or heads are arranged for molding the formed part. With a single suction head, this is also the suction tool. If there are several suction heads that are operated simultaneously, they are all arranged in the common suction tool, so that when the suction tool is moved, the individual suction heads in the suction tool are also moved. The supply of media to the suction tool with a plurality of suction heads is routed in a suitable manner to the individual suction heads in the suction tool.
Placing the suction tool on the pulp means that all of the suction heads provided in the suction tool for the molding of formed parts at least come into contact with the pulp, in such a way that, due to the vacuum or suction pressure applied to the pulp with the suction tool, the fiber material is pulled out of the pulp or the pulp with fiber material dissolved therein is sucked in. During the partial immersion into the pulp, the suction tool is not only placed on the pulp, but immersed into it. The immersion depth of the suction tool in the pulp depends on the respective application and the respective fiber-forming process and can differ depending on the application and possibly the formed part to be formed.
The suction head can have a negative form. A negative form is a form where the suction side of the suction head, i.e., the side where the fiber material is deposited due to the suction effect of the suction head and thus molds the formed part, is on the inside of the suction head, so that this inside, after the suction head has been placed on the pulp or the suction head has been immersed in the pulp, forms a cavity into which the pulp with the fiber material is sucked (as shown in
The suction head can also have a positive form. A positive form is a form where the suction side of the suction head, i.e., the side where the fiber material is deposited due to the suction effect of the suction head and thus forms the formed part, is on the outside of the suction head, so that this outside after the suction head has been placed on the pulp or the suction head has been immersed in the pulp, does not form a cavity (as shown in
The molding of the formed part refers to a first preforming of the formed part, whereby this formed part is formed from fiber material formerly randomly distributed in the pulp by means of accumulation of the fiber material on the contour of the suction head with the corresponding contour. The molded formed part still has a large proportion, for example, 70%-80%, of liquid solution, for example, water, and is therefore not yet dimensionally stable.
By means of the molding station, a formed part is easily molded from a pulp with a fiber material, which can very flexibly deliver formed parts with a wide variety of contours, depending on the configuration of the contour of the suction head. The ratio of width or diameter to height of the formed part does not represent a limiting or critical parameter for the quality of the production of the respective formed part. The molding station described herein makes it possible to produce the formed parts in a very reproducible manner and with great accuracy and quality with regard to the shape and layer thickness of the individual formed part sections. The molding station is able to process fibers of all kinds, as long as they can be dissolved in such a way that extensive clumping of the fibers in the liquid solution can be avoided before processing. In particular, this way, stable formed parts can be produced easily, effectively and flexibly from environmentally-friendly-degradable fiber material with good quality and good reproducibility.
The molding station described herein thus enables, together with subsequent forming steps described herein, the production of environmentally-friendly formed parts from natural fibers in an effective, flexible and reproducible manner with good quality.
In a further embodiment, the suction head suction side of the suction head is formed by a porous screen on a suction side surface of the suction head, wherein, on the pulp side of the screen facing the pulp, the environmentally-friendly-degradable fiber adheres due to the suction. The screen must have a porosity such that the pulp together with the fiber material can be sucked through the screen and the liquid solution of the pulp can pass through the screen. However, the porosity of the screen must not be too large so that the fiber material can adhere to the pulp side.
In a further embodiment, the screen has a wavy structure with wave crests and wave troughs along the suction-side surface, wherein the screen rests at least during suction with the wave crests of its side facing the suction-side surface on the suction-side surface. As a result, the screen is mechanically supported in a simple manner during molding so that its shape does not change and therefore a reproducible shape of the formed part is ensured and on the other hand it can be made porous enough to ensure good suction behavior of the pulp.
In a further embodiment, the suction tool comprises a plurality of suction channels which terminate on the suction-side surface below the screen and are distributed over the suction-side surface in such a way that essentially the same suction power is enabled in all areas between the screen and the suction-side surface. Due to the plurality of suction channels, it is possible, among other things, to suck in pulp with fiber material over the entire surface of the screen, so that the formed part can mold itself on the surface of the screen. The term “substantially” refers here to a homogeneity of the suction power that is sufficient to achieve a uniformly molded formed part without significant layer thickness variations at the corners and edges of the formed part and over the surfaces of the formed part. As a result, the resulting molded formed part has a layer thickness variation of less than 7% from the desired layer thickness. In a further embodiment, the suction channels have openings in the suction-side surface with diameters of less than 4 mm.
In a further embodiment, the suction channels have an uneven distribution on the suction-side surface, with 40%-60% fewer suction channels in the area of negative edges in the formed part and/or 10%-30% more suction channels per unit area in the area of positive edges are arranged than on plane surfaces. As a result of this lower or higher density of suction channels in the area of edges (here refers to all corners and edges, indentations and more significant contour changes in the formed part, negative or positive edges refer to the contour as inner or outer edges), excess or shortage of material in the area of the edges relative to other material thicknesses on surfaces without edges are avoided.
In a further embodiment, the screen is fastened in the suction head only with reversible fastening means, preferably clamping means. As a result, the screens can be quickly and easily removed from the suction tool for cleaning processes or exchanged if necessary. This exchange is also favored, among other things, by the fact that the screen is already supported by it resting on the suction-side surface, which avoids additional brackets. In a further embodiment, the screen is fastened in at least some of the suction channels, if necessary.
In a further embodiment, the suction head comprises, on its end face facing the pulp, a collecting ring for receiving the liquid solution of the pulp sucked through the suction side of the suction head, which collecting ring is connected to a discharge channel for the liquid solution. Among other things, the liquid solution that has passed through the screen can be safely removed from the suction head and thus from the suction tool, so that this liquid solution does not negatively influence the suction power of the suction head.
In a further embodiment, the suction head suction side of the suction head is represented either as a negative form, the suction head inside, or as a positive form, the suction head outside. With regard to the terms “negative form” and “positive form”, reference is made to the explanations above. Depending on the desired shape or contour of the formed part and the further processing, negative forms or positive forms of the suction head can be advantageous.
In a further embodiment, the suction tool is a multi-tool with a plurality of suction heads. With a multi-tool, a plurality of formed parts can be formed simultaneously from a common pulp bath according to the number of suction heads, which increases the throughput of the fiber-forming system and thus allows the fiber-forming system to produce more economically.
In a further embodiment, the shapes of the suction heads in the suction tool can differ at least in part, preferably the same shapes of the suction heads are arranged adjacently in the suction tool. The different shapes can, for example, be arranged in modules in the suction tool. Such a suction tool is able to produce different formed parts simultaneously in the same fiber-forming process. For example, vessels such as cups and the associated lids can be simultaneously formed and further processed in the same suction tool.
In a further embodiment, the suction tool comprises a base plate with suction heads mounted thereon and a gas line system in the base plate, which distributes at least the vacuum provided by a vacuum pump to the suction heads for sucking in the fiber material. The base plate can be connected to the movement unit in a simple and standardized way, while the suction heads mounted on it can differ depending on the desired formed part. The base plate enables the suction heads to be exchanged quickly, if necessary. The vacuum pump can be positioned at a location remote from the suction tool and can distribute the vacuum generated to the suction heads via the gas line system.
In a further embodiment, the gas line system also includes compressed gas lines for applying compressed air to the suction heads. The formed parts can be ejected from the suction tool by a blast of compressed air, for example, after they have been transferred to a hot-pressing lower tool.
In a further embodiment, the gas line system for the vacuum comprises main gas lines and secondary gas lines, wherein the main gas lines are provided for generating a pre-vacuum and the secondary gas lines are provided as a supplement to the main gas lines for achieving the suction vacuum after the suction tool has come into contact with the pulp. In this way, a large volume of gas can be pumped out quickly in order to have a vacuum applied on the suction heads. The process vacuum required for the molding of the formed part can then be quickly adjusted via the suction power on the secondary gas lines, which represent additional pump-out lines to the main lines.
In a further embodiment, one or more valves are suitably arranged in the gas line system to switch off at least one suction pressure at the suction heads as soon as the suction tool has left the pulp and/or to switch on at least the secondary gas lines in addition to the main lines as soon as the suction tool is immersed in the pulp. As a result, the molding process can be made faster and more economical, among other things.
In a further embodiment, the movement unit comprises a robotic arm that can move freely in space and on which the suction tool is mounted. As a result, the molding station can easily and flexibly supply one or more preforming stations and/or one or more hot-pressing stations with molded or preformed formed parts. Thus, the manufacturing process can be accelerated or modified depending on the required production rate, among other things. In a further embodiment, the movement unit is therefore intended to transfer the formed parts in the suction tool to the prepressing station of a preforming station and/or to the hot-pressing station.
In a further embodiment, the robotic arm is connected to the suction tool with a suitable interface that comprises all media supply connections for the suction tool. This means that standardized suction tools can be used, which enable a quick exchange, if necessary.
In a further embodiment, the movement unit is provided for completely immersing the suction head or suction heads into the pulp for contact. Complete immersion is particularly suitable for a suction head as a positive form, since here, in contrast to a negative form: there is no internal cavity in the suction head in which suction pressure (vacuum) can be generated between the pulp and the suction side to suck in the fiber material. In order to ensure that the fiber material is sucked up as evenly as possible, it is advantageous, with a positive form, to completely immerse the suction head in the pulp.
In a further embodiment, the movement unit and the suction tool are configured to leave the molded formed parts in the prepressing station for prepressing in the suction tool after the transfer to the preforming station.
Since the formed part is still relatively moist when it is molded in the suction head and therefore not very dimensionally stable, it is advantageous for a fault-free and qualitatively good process to leave the formed part in the suction head at least until the completion of the prepressing to avoid tool changes for the formed part that could damage its shape. Since the suction tool is the prepressing upper tool in the preforming station, this also speeds up the preforming process.
In a further embodiment, the movement unit and the suction tool are configured to eject the molded formed parts in the hot-pressing station from the suction tool for the subsequent hot-pressing. This can be done, for example, by means of a pressure surge on the preformed formed parts in the suction tool, so that the formed parts can be quickly transferred to the hot-pressing station. In a further embodiment, the movement unit and the suction tool are therefore configured to eject the formed parts from the suction heads of the suction tool using compressed air.
According to a second aspect of the present disclosure, the object is achieved by a preforming station for a fiber-forming system for preforming a formed part from environmentally-friendly-degradable fiber material in a fiber-forming process, comprising
The pulp can contain no organic binder, preferably also no non-organic binder. Without a binder, the formed parts produced from originally environmentally-friendly-degradable fiber material are degradable in a particularly environmentally-friendly manner, since no environmentally-critical binder, preferably no binder at all, is used. The elimination of binders is made possible by the combination of molding, preforming and hot-pressing steps, which as a whole ensure good mechanical interlinking of the individual fibers with one another in the fiber material of the formed part. In the process described herein, the mechanical interlinking is so strong that for the dimensional stability of the formed part binders can be dispensed with. In one embodiment, the environmentally-friendly-degradable fiber material includes (e.g., essentially consists of) fibers with a fiber length of less than 5 mm. With fibers of this length, one obtains, among other things, a good, homogeneous solution of the fiber material in the liquid solution, so that the degree of clumping of the fibers in the pulp is sufficiently low for a good, reproducible fiber-forming process for the formed part. In one embodiment, the pulp is provided at a temperature of less than or equal to 80° C., preferably less than or equal to 50° C., particularly preferably at room temperature. These low temperatures allow, among other things, a simple process control, especially at room temperature. At higher temperatures, the hot-pressing process can be slightly accelerated.
By means of the preforming station, a preformed part that is sufficiently stable for further processing and has a further reduced proportion of liquid solution is produced in a simple manner from a mechanically still unstable part by means of prepressing. Here, too, the ratio of the width or diameter to the height of the formed part does not represent a limiting or critical parameter for the quality of the production of the respective formed parts. The preforming station described herein makes it possible to produce and further process the formed parts in a very reproducible manner and with great accuracy and quality with regard to the shape and layer thickness of the individual formed part sections. In one embodiment, the prepressing can be performed at a temperature of the prepressing station of less than 80° C., preferably less than 50° C., particularly preferably at room temperature. The prepressing reduces the liquid content in the formed part to approx. 55%-65% and the formed part is pre-solidified in such a way that it is sufficiently dimensionally stable for tool transfer. Too high a temperature would lower the liquid content in the formed part too much, which would make the material too stiff for the subsequent hot-pressing. It is exactly the combination of prepressing and hot-pressing that enables the reproducible production of good-quality formed parts with a low level of rejects. In another embodiment, the prepressing is performed at the prepressing pressure between 0.2 N/mm2 and 0.3 N/mm2, preferably between 0.23 N/mm2 and 0.27 N/mm2. These moderate pressures, which are lower than the hot-pressing pressure, enable gentle solidification of the formed part with a moderate reduction in liquid, which is advantageous for a low-waste hot-pressing process.
In particular, this way, stable formed parts can be produced easily, effectively and flexibly from environmentally-friendly-degradable fiber material with good quality and good reproducibility.
The preforming station described herein, together with preceding and subsequent forming steps described herein, thus makes it possible to produce environmentally-friendly formed parts from natural fibers in an effective, flexible and reproducible manner with good quality.
In one embodiment, the preforming station further comprises a pulp preparation and replenishment unit for replenishing the pulp for the reservoir. In this way, the pulp can be fed to the reservoir with controlled quality and constant concentration as it is consumed by molding. The liquid solution discharged during molding can thus be returned to the reservoir after processing, for example, by adding fiber material to set the desired concentration of fiber material in the pulp, and can thus be reused in the fiber-forming process. In a further embodiment, the pulp preparation and replenishment unit therefore fills the reservoir at least periodically, preferably continuously, depending on the pulp consumed by molding the formed part, in order to ensure that the reservoir is filled to the required level for molding.
In a further embodiment, the prepressing station is arranged and configured relative to the reservoir in such a way that the liquid solution removed from the formed part by the prepressing is fed back into the reservoir. In this way, pulp consumption can be reduced. In a further embodiment, the prepressing station is arranged in a vertical alignment thereto above the reservoir, so that the liquid solution removed from the formed part by the prepressing flows back into the reservoir from the prepressing station directly into the reservoir. Alternatively, the liquid solution flows back into the reservoir after preparation by the pulp preparation and replenishment unit of the preforming station.
In a further embodiment, the prepressing station comprises a prepressing lower tool, the shape of which is adapted to the formed part remaining in the suction tool in such a way that it can be placed on the prepressing lower tool in such a way that it is arranged between the prepressing lower tool and the suction tool, so that the suction tool can be pressed onto the prepressing lower tool with prepressing pressure. The suction tool can be pressed onto a stationary prepressing lower tool or the prepressing lower tool is pressed onto a stationary suction tool. The term “place” only refers to the relative movement of the suction tool to the prepressing lower tool. During prepressing, the suction tool represents the prepressing upper tool of the prepressing station. In one embodiment, the suction tool is placed on the prepressing lower tool and pressed onto the prepressing lower tool by means of a separate pressing unit, preferably a piston rod. Alternatively, the suction tool can also be attached to a robotic arm, which itself exerts the prepressing pressure on the prepressing lower tool via the suction tool. Analogously to a suction tool as a multi-tool, the prepressing station can also be designed as a multi-tool with a plurality of prepressing lower tools adapted to the suction tool as a multi-tool in order to apply the prepressing pressure to all molded formed parts of the suction tool simultaneously and thus the carry out the prepressing for all formed parts simultaneously. Alternatively, the prepressing can be performed as membrane pressing, wherein the prepressing lower tool is designed as a flexible membrane and the prepressing pressure is applied to the membrane as gas pressure, which membrane is then pressed onto the outer contour of the formed part. Membrane pressing is particularly suitable for geometries of the formed part where pressure is to be exerted on a large area. Membrane pressing can also be used to simultaneously apply the same pressure to surfaces that are perpendicular to one other in any spatial orientation, since in membrane pressing the prepressing pressure is generated by means of gas pressure, for example, by means of compressed air, which acts on the membrane irrespective of the direction. This would not be possible with a pressure piston rod, for example. Rubber membranes, for example, can be used as membranes. The membrane should have a contour fidelity of less than 20% and can be designed differently locally, for example, with thinner and thicker walls and/or arranged closer to the contour or further away from it.
In a further embodiment, the prepressing lower tool has a pressing surface facing the formed part, the pressing surface having a lower surface roughness than the screen. As a result, homogeneous pressure is exerted on the formed part. In addition, the adhesion between the prepressing lower tool and the formed part is lower than with structured surfaces of the prepressing lower tool, which ensures that the prepressed formed parts remain in the suction tool for transfer to the hot-pressing station without further technical measures and do not remain on the prepressing lower tool, which would cause a disruption in the production process. If necessary, the suction tool can generate a suitable vacuum in the suction tool for the transfer of the prepressed formed parts to the hot-pressing station in order to improve the adhesion of the formed parts to the suction tool.
In a further embodiment, the prepressing lower tool is made of metal or at least partially made of elastomer, preferably made of silicone. Metal prepressing lower tools are particularly suitable for cases where a temperature above room temperature or a particularly high prepressing pressure is to be applied during prepressing. Prepressing lower tools made of an elastomer or at least partly made of elastomer are advantageous for multi-tools as suction tool and prepressing lower tool, since the elastomer can still be easily deformed under pressure and thus adapts flexibly to a multi-suction tool that may bend under the prepressing pressure and thus improves the homogeneity of the shaping of the various formed parts in the multi-suction tool. For increased prepressing temperatures below 100° C., for example, silicone as an elastomer is also well suited as a temperature-resistant material in this range.
In a further embodiment of prepressing lower tools, at least partially made of elastomer, said prepressing lower tools have a cavity which is surrounded by a wall made of the elastomer as a pressing surface, wherein the prepressing station is configured to apply gas pressure to the cavity during prepressing in order to generate the prepressing pressure or at least support it. This “inflating” of the prepressing lower tool allows it to conform particularly well to the contour of the formed part, so that the quality of the preforming process is improved, particularly for the reproducible production of very identical formed parts.
In a further embodiment, the prepressing lower tools are arranged on a common carrier plate, which is configured as an interface to the prepressing station for reversible attachment to the prepressing station and/or for supplying the individual prepressing lower tools with gas pressure. Among other things, this means that the prepressing lower tool can also be quickly exchanged as a multi-tool if required.
In a further embodiment, the carrier plate additionally comprises a heating element, preferably a heating element extending over the surface of the carrier plate, for heating the lower prepressing tools. This modular structure facilitates the handling of the components and their exchangeability.
In a further embodiment, the molding station is part of the preforming station. As a result, the molding station can be connected to the preforming station via suitable lines in such a way that the liquid solution and/or fiber material that has passed through the suction head is fed back into the pulp via the preforming station.
In a further embodiment, the suction tool having the negative form as the suction head suction side is placed on the prepressing lower tool (with a corresponding positive form) or having the positive form as the suction head suction side is inserted in the prepressing lower tool (as a corresponding negative form).
The object is achieved according to a third aspect of the present disclosure by a hot-pressing station for a fiber-forming system for the final shaping of a formed part made of environmentally-friendly-degradable fiber material in a fiber-forming process, comprising a hot-pressing lower tool adapted to a contour of the formed part for receiving the formed part and a hot-pressing upper tool adapted accordingly to the formed part for placing onto or inserting into the formed part along a closing direction of the hot-pressing station, wherein the hot-pressing lower tool and/or the hot-pressing upper tool are provided for exerting a hot-pressing pressure on the formed part arranged between the hot-pressing lower tool and the hot-pressing upper tool during hot-pressing.
After prepressing has taken place, the preformed formed part is transferred to the hot-pressing station by means of the suction tool, with the formed part being removed from the suction tool for subsequent hot-pressing. The transfer is advantageous in that the hot-pressing is performed at a high temperature with a significantly higher pressure. If the formed part were to remain in the suction tool without being transferred for hot-pressing, the fiber material could get caught in the screen of the suction tool and, after hot-pressing, be removed from the suction tool only with difficulty, possibly only with damage. In addition, the screen could be damaged by the high pressure, so that the suction tool would then no longer be functional. The transfer can take place in such a way that the formed part or parts are transferred from the suction tool to the hot-pressing station either passively by depositing them or actively by means of an ejection pressure in the suction tool against the formed parts. With the hot-pressing of the prepressed formed part with a hot-pressing pressure, the formed part is final-shaped with a further reduction in the proportion of the liquid solution in the formed part, for example, to below 10%, preferably to approximately 7%, after which it is then stable and dimensionally stable. Preferably, the hot-pressing lower and upper tools are made of metal. The hot-pressing is performed at the hot-pressing pressure which is higher than the prepressing pressure, for example, at a hot-pressing pressure between 0.5 N/mm2 and 1.5 N/mm2, preferably between 0.8 N/mm2 and 1.2 N/mm2. The hot-pressing pressure can be applied for a pressing time of less than 20 s, preferably more than 8 s, particularly preferably between 10 and 14 s, even more preferably 12 s. The hot-pressing pressure is applied hydraulically to the hot-pressing station, for example, via a piston rod, which piston rod presses, for example, on the hot-pressing upper tool, which in turn presses on the stationary hot-pressing lower tool, with the formed part in between. The arrangement could also be reversed.
The hot-pressing station is a simple way of producing a preformed and still slightly variable formed part by means of hot-pressing a final-shaped formed part with a significantly reduced proportion of liquid solution for further processing. Here, too, the ratio of the width or diameter to the height of the formed part does not represent a limiting or critical parameter for the quality of the production of the respective formed parts. The hot-pressing station described herein makes it possible to produce and further process the formed parts in a very reproducible manner and with great accuracy and quality with regard to the shape and layer thickness of the individual formed part sections. In particular, it is possible in this way to produce end-stable formed parts in a simple, effective and flexible manner from environmentally-friendly-degradable fiber material with good quality and good reproducibility.
The hot-pressing station described herein, together with previous forming steps described herein, thus makes it possible to produce environmentally-friendly formed parts made of natural fibers in an effective, flexible and reproducible manner with good quality.
In one embodiment, in the case of a negative form of a suction tool, the hot-pressing lower tool also has a negative form and is provided as an inner tool, while the hot-pressing upper tool is placed on it as an outer tool for hot-pressing. In the case of a positive form of the suction tool, the hot-pressing lower tool also has a positive form and is provided as an outer tool, while the hot-pressing upper tool is inserted in the hot-pressing lower tool as an inner tool for hot-pressing. The two hot-pressing upper and lower tools can work together to apply high pressures at high temperatures to the formed part in between them.
In a further embodiment, the respective hot-pressing sides of the hot-pressing lower tool and the hot-pressing upper tool facing the formed part are heated by means of electric heating cartridges. Electric heating cartridges enable rapid heating of the hot-pressing lower tool and the hot-pressing upper tool when the tools are closed, after the tools have cooled down by opening the hot-pressing station to remove the final-shaped parts.
In a further embodiment, the heating cartridges in the hot-pressing lower tool and hot-pressing upper tool are configured and arranged in such a way that the hot-pressing sides are heated to temperatures greater than 150° C., preferably between 180° C. and 250° C. This means that the liquid (or moisture) in the formed part can be reduced quickly and reliably to below 10%.
In a further embodiment, the heating cartridges are controlled in such a way that the temperatures of the hot-pressing lower tool and the hot-pressing upper tool differ. Among other things, this gives the formed part a better surface, especially on the warmer side. Preferably, the hot-pressing upper tool has a higher temperature than the hot-pressing lower tool: the temperatures preferably differ by at least 25° C., preferably not more than 60° C., particularly preferably by 50° C.
In a further embodiment, the heating cartridges are arranged close to the contour of the formed part in the respective hot-pressing upper tools and hot-pressing lower tools. The heating cartridges that are close to the contour heat the hot-pressing side up to the process temperature more quickly, which speeds up the hot-pressing process. The respective hot-pressing upper tools and hot-pressing lower tools are preferably made of metal in order to support this by means of good heat conduction.
In a further embodiment, at least one heating cartridge with a first heating output is arranged in the inner tool, while a plurality of heating cartridges with second heating outputs are arranged in the outer tool around the hot-pressing side of the outer tool. With this arrangement, rapid heating is achieved with the smallest possible number of heating cartridges. For this purpose, the first heating output is preferably greater than the second heating output. In a further embodiment, in the case of a single heating cartridge in the inner tool, said heating cartridge is arranged centrally in the inner tool parallel to the closing direction, and/or in the case of several heating cartridges, said heating cartridges are arranged in the inner tool concentrically around the closing direction parallel to the hot-pressing side of the inner tool. In a further embodiment, a plurality of heating cartridges is arranged in the outer tool concentrically around the closing direction and parallel to the hot-pressing side of the outer tool.
In a further embodiment, the hot-pressing lower tools and/or the hot-pressing upper tools comprise a covering made of a thermally insulating material on the sides facing away from the formed part, to keep the process temperature as constant as possible and to keep the necessary heating output of the heating cartridges as low as possible.
In a further embodiment, the hot-pressing lower tool comprises channels on its hot-pressing side, with which the liquid solution can be at least partially discharged during hot-pressing. By reducing the liquid (or moisture) in the formed part from approx. 55%-60% to below 10%, a quantity of liquid is released, which at least partially evaporates due to the high temperatures during hot-pressing. This steam is discharged via the channels so that the formed part is not damaged by the steam, among other things. For this purpose, the channels preferably have a diameter of less than or equal to 1.0 mm, at least on the hot-pressing side.
In a further embodiment, both the hot-pressing lower tool and the hot-pressing upper tool are designed as a multi-tool with a plurality of hot-pressing lower tools and hot-pressing upper tools arranged on respective carrier plates for the respective hot-pressing lower tools and hot-pressing upper tools. In this way, after the transfer, the hot-pressing pressure can be applied to all preformed formed parts from the suction tool simultaneously, and the hot-pressing can thus be performed simultaneously for all formed parts.
In a further embodiment, the carrier plates in the hot-pressing station are laterally movably mounted to facilitate a tool change of the respective hot-pressing lower tools and hot-pressing upper tools as multi-tools outside of a process space of the hot-pressing station. This means that changes can be performed quickly and in a space-saving manner.
In a further embodiment, the carrier plate of the hot-pressing upper tools of the multi-tool is provided with gas lines in order to, depending on the process step, apply a vacuum in the respective hot-pressing upper tools to hold the formed parts in and/or an overpressure to eject the final-shaped formed parts from the hot-pressing upper tools.
In a further embodiment, expansion means are arranged between the carrier plate and a holder for the carrier plate to compensate for high temperatures and temperature fluctuations due to the opening and closing of the hot press station relative to the supports and other components.
In a further embodiment, thermally insulating material is arranged between the carrier plate and the holder in order to keep the process temperature as constant as possible and to keep the necessary heating output of the heating cartridges as low as possible.
The present disclosure also relates to a fiber-forming system for producing formed parts from environmentally-friendly-degradable fiber material, comprising at least a molding station described herein, a preforming station described herein, and a hot-pressing station described herein for producing a formed part from environmentally-friendly-degradable fiber material by means of a fiber-forming process performed in the fiber-forming system.
The combination of molding by means of pulp and a suction tool, prepressing by means of a preforming station, and hot-pressing by means of a hot-pressing station makes it easy to produce a formed part from a fiber material that, depending on the design of the contour of the suction head, can very flexibly deliver formed parts with a wide variety of contours. The ratio of width or diameter to height of the formed part does not represent a limiting or critical parameter for the quality of the production of the respective formed part. Through the combination of the suction tool for molding and the preforming and hot-pressing stations, the formed parts can be produced very reproducibly and with great accuracy and quality in terms of shape and layer thickness of the individual formed part sections. The fiber-forming system described herein is able to process fibers of the most varied types, provided that they can be dissolved in such a way that extensive clumping of the fibers in the liquid solution prior to processing can be avoided. In particular, this way, stable formed parts can be produced easily, effectively and flexibly from environmentally-friendly-degradable fiber material with good quality and good reproducibility.
The fiber-forming system described herein thus makes it possible to produce environmentally-friendly formed parts from natural fibers in an effective, flexible and reproducible manner with good quality.
In one embodiment, the fiber-forming system comprises a control unit for controlling at least the molding station, the preforming station and the hot-pressing station and their sub-components. The control unit can be designed as a processor, separate computer system or can be web-based and is suitably connected to the components of the fiber-forming system to be controlled, for example, via data cable or wirelessly using WLAN, radio or other wireless transmission means.
In a further embodiment, the fiber-forming system also comprises a coating unit for applying one or more functional coatings to the formed part. With such functional coatings, additional functionalities such as moisture, aroma, odor or taste barriers or barriers against fats, oils, gases such as O2 and N2, light acids and all substances that contribute to the perishability of food and/or non-food-grade substances are applied to the formed part. For this purpose, the coating unit can be arranged at any position in the process sequence for producing the formed part that is suitable for the coating to be applied. Depending on the application, the functional coating can be arranged in the suction process, after prepressing or after hot-pressing. The term “functional coating” refers here to any additional coating applied to the original fiber material that is applied both to an inner side and/or to an outer side of the formed part over the whole area or in partial areas.
In a further embodiment, the fiber-forming system additionally comprises an ejection unit for ejecting the final-shaped formed part. The ejection unit ejects the formed part for further transport or for further processing, for example, to subsequent cutting, inscribing, printing, stacking and/or packing stations, for example, with the aid of a conveyor belt.
The present disclosure also relates to a method for producing formed parts from environmentally-friendly-degradable fiber material by means of a fiber-forming process in a fiber-forming system described herein, comprising the following steps:
It should be expressly pointed out that, for the purpose of better readability, “at least” expressions have been avoided as far as possible. Rather, an indefinite article (“one”, “two” etc.) is normally to be understood as “at least one, at least two, etc.”, unless it follows from the context that “exactly” the specified number is meant there.
At this point it should also be mentioned that within the scope of the present patent application, the expression “in particular” is always to be understood in such a way that an optional, preferred feature is introduced with this expression. The expression is therefore not to be understood as “specifically” and not as “namely”.
It goes without saying that features of the solutions described above or in the claims can also be combined if necessary in order to be able to cumulatively implement the advantages and effects that can be achieved here.
In addition, further features, effects and advantages of the present disclosure are explained with reference to the attached drawing and the following description. Components which at least essentially correspond in terms of their function in the individual figures are identified by the same reference signs, with the components not having to be numbered and explained in all figures.
Exemplary embodiments of the technical teaching described herein are shown below with reference to the figures. Identical reference signs are used in the figure description for identical components, parts and processes. Components, parts and processes which are not essential to the technical teachings disclosed herein or which are obvious to a person skilled in the art are not explicitly reproduced. Features specified in the singular also comprise the plural unless explicitly stated otherwise. This applies in particular to statements such as “a” or “one.”
Pulp refers to an aqueous solution containing fibers, wherein the fiber content of the aqueous solution can be in a range of 0.1 to 10 wt. %. In addition, additives such as starch, chemical additives, wax, etc. can be contained. The fibers can be, for example, natural fibers, such as cellulose fibers, or fibers from a fiber-containing original material (for example waste paper). A fiber treatment plant offers the possibility of preparing pulp in a large quantity and providing a plurality of fiber processing devices 1000.
The fiber processing device 1000 can be used to produce, for example, biodegradable cups 3000, capsules, trays, plates, and other molded and/or packaged parts (e.g., as holder/supporting structures for electronic appliances). Since a fibrous pulp with natural fibers is used as the starting material for the products, the products manufactured in this way can themselves be used as a starting material for the manufacture of such products after their use, or they can be composted, because they can usually be completely decomposed and do not contain any substances that are harmful to the environment.
The fiber processing device 1000 shown in
The control unit 310 is in bidirectional communication with an HMI panel 700 via a bus system or a data connection. The HMI (Human Machine Interface) panel 700 has a display which displays operating data and states of the fiber processing device 1000 for selectable components or the entire fiber processing device 1000. The display can be designed as a touch display so that adjustments can be made manually by an operator of the fiber processing device 1000. Additionally or alternatively, further input means, such as a keyboard, a joystick, a keypad, etc. for operator inputs, can be provided on the HMI panel 700. In this way, settings can be changed and the operation of the fiber processing device 1000 can be influenced.
The fiber processing device 1000 has a robot 500. The robot 500 is designed as a so-called 6-axis robot and is thus able to pick up parts within its radius of action, to rotate them and to move them in all spatial directions. Instead of the robot 500 shown in the figures, other handling devices can also be provided that are designed to pick up and twist or rotate products and move them in the various spatial directions. In addition, such a handling device may also be otherwise configured, in which case the arrangement of the corresponding stations of the fiber processing device 1000 may differ from the exemplary embodiment shown.
A suction tool 520 is arranged on the robot 500. In the exemplary embodiment shown, the suction tool 520 has cavities formed as negatives of the three-dimensional molded parts to be formed, e.g., cups 3000, as suction cavities 522. The suction cavities 522 can have, for example, a net-like surface on which fibers from the pulp are deposited during the suction. Behind the net-like surfaces, the cavities are connected to a suctioning device via channels in the suction tool 520. The suctioning device can be realized, for example, by a suction device 320 or a fan. Pulp can be suctioned in via the suctioning device when the suction tool 520 is located within the pulp tank 250 in such a way that the suction cavities 522 are at least partially located in the aqueous fiber solution, the pulp. A vacuum, or a negative pressure, for suctioning fibers, when the suction tool 520 is located in the pulp tank 250 and the pulp, can be provided via the suction device 320. For this purpose, the fiber processing device 1000 has corresponding means at the supply units 300. The suction tool 520 has lines for providing the vacuum/negative pressure from the suction device 320 in the supply units 300 to the suction tool 520 and the openings in the suction cavities 522. Valves are arranged in the lines, which can be controlled via the control unit 310 and thus regulate the suction of the fibers. It is also possible for the suction device 320 to perform a “blow-out” instead of a suction, for which purpose the suction device 320 is switched to another operating mode in accordance with its design.
During the production of molded parts made of a fiber material, the suction tool 520 is immersed in the pulp and a negative pressure/vacuum is applied to the openings of the suction cavities 522 so that fibers are suctioned out of the pulp and are deposited for example on the network of suction cavities 522 in the suction tool 520.
Thereafter, the robot 500 lifts the suction tool 520 out of the pulp tank 250 and moves said tool together with the fibers that are adhering to the suction cavities 522 and still have a relatively high moisture content of, e.g., over 80 wt. % water, to the pre-pressing station 400 of the fiber processing device 1000, the negative pressure being maintained in the suction cavities 522 for the transfer. The pre-pressing station 400 has a pre-pressing tool with prepress molds 410. The prepress molds 410 can be formed, for example, as positives of the molded parts to be manufactured and have a corresponding size with regard to the shape of the molded parts in order to receive the fibers adhering in the suction cavities 522.
During the production of molded parts, the suction tool 520 is moved, with the fibers adhering in the suction cavities 522, to the pre-pressing station 400 in such a way that the fibers are pressed into or against the suction cavities 522. The fibers are pressed together in the suction cavities 522, so that a stronger connection is thereby produced between the fibers. In addition, the moisture content of the preforms formed from the suctioned-in fibers is reduced, so that the preforms formed after the pre-pressing only have a moisture content of, for example, 60 wt. %. To squeeze out water, flexible prepress molds 410 can be used, which are inflated, for example, by means of compressed air (process air), and in the process press the fibers against the wall of a suction cavity 522 in a further suction tool part. As a result of the “inflation,” both water is squeezed out, and the thickness of the sucked-in fiber layer is reduced.
During the pre-pressing, liquid or pulp can be extracted and returned via the suction tool 520 and/or via further openings in prepress molds 410 or pre-pressing tool parts (cavities).
After pre-pressing in the pre-pressing station 400, the preforms produced in this way are moved to a hot pressing station 600 on the suction tool 520 via the robot 500. For this purpose, the negative pressure is maintained at the suction tool 520 so that the preforms remain in the suction cavities 522. The preforms are transferred via the suction tool 520 to a lower tool body 620 which can be moved along the production line out of the hot pressing device 610. If the lower tool body 620 is in its extended position, the suction tool 520 is moved to the lower tool body 620 in such a way that the preforms can be placed on forming devices of the lower tool body 620. Subsequently, an overpressure is generated via the openings in the suction tool 520 so that the preforms are actively deposited by the suction cavities 522, or the suction is ended, so that the preforms remain on the forming devices of the lower tool body 620 due to gravity. By providing overpressure at the openings of the suction cavities 522, pre-pressed preforms resting/adhering in the suction cavities 522 can be released and dispensed.
Thereafter, the suction tool 520 is moved away via the robot 500 and the suction tool 520 is dipped into the pulp tank 250 in order to suction further fibers for the production of molded parts from fiber-containing material.
After the transfer of the preforms, the lower tool body 620 moves into the hot pressing station 600. In the hot pressing station 600, the preforms are pressed under heat and high pressure so as to produce finished molded parts, for which purpose an upper tool body 630 is brought onto the lower tool body 620 via a press. The upper tool body 630 has cavities corresponding to the forming devices. After the hot-pressing process, the lower tool body 620 and the upper tool body 630 are moved away from one another, and the upper tool body 630 is moved along the fiber processing device 1000 in the manufacturing direction: then, after the hot pressing, the molded parts are suctioned in via the upper tool body 630 and thus remain within the cavities. Thus, the manufactured molded parts are brought out of the hot pressing station 600 and deposited via the upper tool body 630 after traveling on a transport belt of a conveying device 800. After the molded parts are deposited, the suction via the upper tool body 630 is ended and the molded parts remain on the transport belt. The upper tool body 630 moves back into the hot-pressing station 600, and a further hot-pressing process can be carried out. Alternatively, the lower tool body 620 can be moved in an opposite direction prior to being extended to receive the preforms in order to move the manufactured products/molded parts out of the hot pressing device for further transport.
The fiber processing device 1000 further has a conveying device 800 with a transport belt. The manufactured molded parts made of fiber-containing material can be placed on the transport belt after the final molding and the hot pressing in the hot pressing station 600 and discharged from the fiber processing device 1000. In further embodiments, after placing the molded parts on the transport belt of the conveying device 800, further processing can take place, such as filling and/or stacking the products. The stacking can take place, for example, via an additional robot or another device.
The fiber processing device 1000 from
The elastic material 442 is perforated and has a plurality of small openings, as indicated schematically in
In the embodiment of
In contrast to designs known from the prior art, the mold body 420 does not require a support structure made of a metal block or the like to support the mold body 420. So that the mold body 420 cannot collapse, the mold body 420 has an internal support structure 440 which is formed integrally with a shell 480 and includes (e.g., essentially consists of) an elastic material. The shell 480 and the support structure 440 can be made of the same material and can be manufactured for example using an additive manufacturing process (e.g., 3D printing) to provide the integral formation of the shell 480 and the support structure 440. Silicones or thermoplastic elastomers, especially thermoplastic polyurethanes (TPU), can be used as the elastic material.
The support structure 440 has a plurality of struts 460 which are connected or integrally formed with the inside of the shell 480 via a first end in a connection section 462. In the shown embodiment, second ends are connected to the tool body 402 in connection sections 464.
The ends in the connection sections 462 can be connected here in accordance with the shape of the shell 480, wherein the shell 480 itself substantially has the geometry of a molded part to be produced or of the preform to be pressed. In the connection sections 462, the material of the shell 480 is held back more strongly than in sections of the shell 480 which are not connected to a strut 460. Therefore, an optimal distribution and dimensioning of the connection sections 462 is crucial for determining the deformability of the shell 480, in addition to the material of the shell 480 and of the struts 460. In addition, a targeted arrangement and connection of struts 460 can counteract a collapse of the shell 480 if the struts 460 jointly ensure that the shell 480 retains its basic structure. Although external pressure on the shell 480 can cause it to be slightly deformed and pressed inward, the shell 480 automatically returns to its initial position after the pressure application has ceased due to the flexible material of the shell 480 and the support structure 440 and their design.
The support structure 440 and its struts 460 can, in all embodiments, have sections that are open-pored and/or have hollow spaces in order to influence the mechanical properties of the support structure 440 and/or struts, 460 and/or to save weight and material.
A supply (feed) channel 404 is provided in the tool body 402, through which compressed air can be introduced. The introduced compressed air then flows out into an interior space 490 and causes a deformation or “inflation” of the flexible material 422 of the shell 480 of the mold body 420. Depending on the thickness and the employed material for the flexible material 422, the pressure and volume flow of the introduced compressed air, as well as other factors such as the perforation of the flexible material 422, the deformability of the shell 480 can be influenced and controlled. Furthermore, the deformability is determined by the number and design of the struts 460 as well as their connection to the inside of the shell 480.
In the shown embodiment, the shell 480 has sections with substantially the same wall thickness and sections with elevations 470. The elevations 470 are located in sections which are situated opposite transitions in the mold surface of the suction cavity 522, as shown schematically in
The previously indicated wall thickness of the shell 480 extends substantially over the surface of the mold body 420 (product section) that is in contact with the preform to be pressed during the pre-pressing.
The connection unit 432 also has an opening 434 which, in the connected state of the pre-press mold 410 and the tool body 402, is congruent with the feed channel 404 so that a medium (gas, gas mixture) can be introduced into the interior space 490 in order to deform the shell 480.
The connection unit 432 can additionally have connecting elements such as threaded holes, etc., so that the connection unit 432 and thus the entire pre-press mold 410 can be reversibly connected to the tool body 402.
In further embodiments, the connection units 432 shown in the figures can also be reversibly connected to a tool body 402 via clamping, locking, or snap connections.
On the one hand, the elevations 470 press into the transitions in a targeted manner and, on the other hand, the deformation of the shell 480 is significantly influenced by the support structure 440, since the struts 460 counteract deformation.
During pre-pressing, the suction tool 520 with the suction cavities 522 is moved to the pre-pressing tool. Fibers from the pulp are deposited on nets or other similarly designed surfaces in the suction cavities 522.
After the tool body 526 has come into contact with the tool body 402, the pre-pressing process can be started, for which purpose, for example, compressed air is introduced into the interior space 490 of the mold body 420 for the deformation. Uniform deformation of the flexible material 422 takes place in the process and thus a uniform pre-pressing.
After the mold body 420 is arranged in the suction cavity 522 with the fiber-containing material 900 previously suctioned in, the pre-pressing process starts, and the fiber-containing material 900 or the preform is pressed and dewatered, wherein the wall thickness of the preform is reduced. Preforms are located within the mold cavity shown in
The figures show only a partial view of a prepress mold 410 and a suction cavity 522. In further embodiments, a pre-pressing tool and a suction tool 520 can be designed as multi-cavity tools and thus have a plurality of suction cavities 522 and corresponding prepress molds 410.
In all embodiments shown in the figures, the elastic material of the shell 480 can be perforated and have openings 428, as shown schematically in
The formation of mold bodies 420 described herein makes it possible to pre-press fiber-containing material 900 which rests on a surface (e.g. mesh) of a suction cavity 522 of a suction tool 520 and, as shown schematically in the figures, can often have varying layer thicknesses, in such a way that the fiber-containing material 910 after pre-pressing, or the resulting preforms, have a defined wall thickness over the entire geometry of the preform, and the moisture content is significantly reduced. The teaching described herein enables optimization with regard to the pre-pressing effect, since this depends strongly on the product geometry and the material. This includes the product-specific, local adjustment of stiffness, geometry, porosity, as well as the offset (distance between the tools before inflation). This enables significantly higher (>40%, up to 50%) and more uniform dry contents across the product surface to be achieved compared to known pre-pressing stations. In addition, the pre-pressing time can be reduced because the entire surface is acted on with the same elevated efficiency (pressure, air flow).
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2019 127 562.8 | Oct 2019 | DE | national |
| 10 2024 118 514.7 | Jul 2024 | DE | national |
The present application is a continuation-in-part of U.S. application Ser. No. 17/754,791, entitled “FIBRE MOULDING PLANT FOR PRODUCING MOULDED PARTS FROM ENVIRONMENTALLY DEGRADABLE FIBRE MATERIAL,” filed Apr. 12, 2022 (now U.S. Pat. No. 12,071,731), which is a 371 filing of International Patent Appl. PCT/DE2020/000230, filed Oct. 1, 2020, and claims priority to German Patent Application No. DE 10 2019 127 562.8, filed Oct. 14, 2019, the disclosures of which are incorporated by reference herein in their entirety. The present application also claims priority under 35 U.S.C. § 119 to German Patent Application No. DE 10 2024 118 514.7, filed Jul. 1, 2024, the disclosure of which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17754791 | Apr 2022 | US |
| Child | 18807263 | US |
