Tool for Processing Fiber-Containing Material, Molding Plant and Method for Manufacturing Fiber-Containing Products

The present application claims priority under 35 U.S.C. § 119 to German Patent Application No. DE 10 2024 107 894.4, filed Mar. 20, 2024, the disclosure of which is incorporated by reference herein in its entirety.

A tool for processing fiber-containing material for the manufacture of three- dimensional products, a molding plant for manufacturing fiber-containing products and a method for the manufacture of fiber-containing products are described.

Fiber-containing materials are sometimes 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 that can be obtained, for example, from renewable raw materials or waste paper.

Fiber-containing materials can be processed in a moist state in a so-called “wet fiber” molding process, whereby natural fibers are mixed, for example, in an aqueous fiber suspension (pulp) and possibly other additives such as starch. This pulp can for example have a proportion of natural fibers of, for example, 0.5 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. Additives in a pulp can also have effects on color, barrier properties and mechanical properties.

To produce three-dimensional products from the pulp, the fibers are suctioned via a suction tool, where the fibers then adhere to the surface (suction surface) of a suction body, which substantially corresponds to the geometry of a product to be manufactured. In so doing, the suction also causes a dewatering of the suctioned fiber mat or the preform resulting therefrom. As a rule, such a moist preform has a moisture content of 50 to 70 wt. % after suction.

A device and a manufacturing method for manufacturing products from fibers are known from DE 10 2019 127 562 A1, for example.

After the fibers have been suctioned, it has been suggested to pre-press the fiber mat in order to further dewater and strengthen it. For this purpose, it is also known to spray the underside of the suction tool with water using a spray bar in order to remove or align fibers in the edge section of the suction body so that the fiber mats have a smooth edge formation without fringes etc. even before pre-pressing, which consequently improves the formation of the edge of fiber-containing products in the subsequent manufacturing method.

When fibers are suctioned, especially two types of undesirable fiber deposits can arise that remain throughout subsequent processing and lead to protruding fibers in the edge section of the finished product. The fibers that collect on the suction surface during suction in the cavity of a suction body of the suction tool and form a composite there, show a tendency in the edge section to settle along the direction of movement on a stripping edge (type I). In order to remove fiber protrusions on an inner edge of the cavity, pre-pressing bodies of a pre-pressing tool can have a lip that pushes protruding fibers along the stripping edge towards the cavity. If fibers protrude beyond the area in which the lip grips into the edge section, it pinches them off. This results in fiber protrusions. These usually remain throughout the process and ultimately lead to excess fiber on the outer edge of the final product. The excess appears there in the form of frayed and wavy edges.

During suctioning, the suction tool dips into a pulp tank in the direction of the bottom. When leaving this tank, another form of undesirable fiber deposits (Type II) arises, where fiber lumps from the pulp are deposited on the tool surface. If lumps settle in the edge section of the cavities, they are usually also clamped by the lip of a pre-pressing body. The resulting overhangs remain throughout the process and form large protrusions on the final product.

However, known designs of a spray bar do not ensure reliable cleaning of a product edge section since a spray bar only moves along a linear axis from the upper cavity end to the lower one. The linear axis leads to different relative speeds at the differently aligned stripping edges. An edge that is aligned perpendicular to the movement of the spray bar is generally cleaned less reliably than an edge that runs horizontal to the spray axis movement.

Furthermore, it is not possible to specifically clean the edge section of cavities with a spray bar. Instead, a carrier plate for the cavities is sprayed completely, along with all the cavities installed thereon. Depending on the size and number of installed cavities, only a comparatively small part of a jet falls on the critical edge section. This also means that the interior section of the cavities that are already filled with fibers at this point, are sprayed with the jet. This resoftens the fibers. Furthermore, lumps of fibers can come loose and partially deposit in the edge section that was originally supposed to be freed of fibers. Furthermore, such a fiber displacement not only causes the contamination of the edge section but also a contamination of the machine compartment.

As a result, it is therefore still necessary to rework the edges of such products. Furthermore, a high use of resources (water, energy, etc.) and complex machine design are required. Ultimately, this leads to a major soiling of machines and machine components.

In contrast thereto, it is an object to provide a solution that eliminates the disadvantages of the prior art. It is another object to optimize the edge formation as early as possible in a fiber processing process. Furthermore, it is an object to keep the effort and installation space for edge formation low. Moreover, it is an object to keep the use of resources low.

The above-mentioned objects are achieved by a tool for processing fiber-containing material for the production of three-dimensional products, having a mold body with a three-dimensional surface that substantially reflects the shape of a product to be molded, where the mold body has a peripheral edge section, further having a spray arrangement via which a medium for aligning fibers in the edge section of the mold body and/or for aligning fibers in an edge section of an opposing tool with an further mold body can be dispensed.

The integration of a spray arrangement into the tool (suction tool or pre-pressing tool) for processing fibers offers the advantage of discharging a medium as a media flow in a targeted manner and bringing it to a section that is essential for edge formation. This means that irrelevant sections are not sprayed, and the spraying only strikes the relevant sections in the desired alignment and strength for the given application.

The employed medium can be, for example, water, a gas or gas mixture (e.g., air) or an air-water mixture. In other embodiments, other media (liquids) or additives for the above-described media can also be used, in order for example to influence the connection of fibers and/or (barrier) properties.

The media flow exiting via the spray arrangement, which for example can have several outlets, can be directed, for example, onto another opposing tool so that the fibers on the opposing tool can be pressed into a cavity in an edge section. Alternatively or additionally, fibers that protrude beyond an edge section on the opposing tool can be sprayed away. As a result, a clear edge is formed without protruding fibers. During subsequent processing, the edge only becomes drier and firmer so that no impairment of edge formation thereby occurs. Accordingly, final products have an edge formation without fraying.

The spray arrangement can be designed in such a way that a media flow emerging via, for example, several outlets specifically strikes sections of, for example, an opposing tool and fibers, and thereby deflects and/or moves them.

The outlets themselves can be designed in other embodiments, for example as nozzles. Instead of nozzles, simple holes, slots, etc. can also be outlets that enable “spraying”.

In other embodiments, the mold body and the further mold body of an opposing tool can be designed differently. For example, a corresponding pair of tools can be a suction tool and a pre-pressing tool. Instead of completely spraying the underside of a suction tool with the aid of a spray bar after suction, as previously known from the prior art, a media flow is dispensed via the spray arrangement on one of the tools at a determinable distance between the pre-pressing tool and the suction tool. Since the two tools are coordinated with each other with regard to the design of the products to be manufactured, the media flow in the edge section always strikes a corresponding edge section of the opposing tool. Furthermore, in one of the two tools, the spray arrangement and the amount of dispensed medium can be specifically tailored to the design of the other tool corresponding to the alignment of outlets, e.g., nozzles.

In other embodiments, the spray arrangement can have outlets that are arranged at regular intervals so that uniform spraying can take place.

In other embodiments, the spray arrangement can have a common reservoir for providing a medium for the outlets (e.g., nozzles) so that pressure equalization is provided, and the pressure or media output is uniform at all outlets.

In other embodiments, the spray arrangement can have at least one supply to the reservoir. In still other embodiments, multiple feeds can be provided that are evenly, preferably arranged symmetrically distributed so that the delivery of a uniform media flow at all outlets is further supported.

In other embodiments, the spray arrangement can have at least one deflection arrangement for deflecting and/or fanning out an emerging media flow. The deflection arrangement can, for example, have a deflection tongue. This makes it possible to fan out a media flow. In addition, this allows the direction of the dispensed media flow to be set with regard to the design of a corresponding tool (opposing tool).

In other embodiments, the deflection arrangement can have a continuous deflection edge running parallel to the edge section of the mold body. The deflection arrangement can, for example, have a circumferential deflection edge. The deflection edge can be designed in such a way that a circulating media flow is emitted via outlets of the spray arrangement, which, like a “curtain,” strikes the edge section of an opposing tool substantially evenly.

In other embodiments, the deflection arrangement can have a deflection angle for a media flow exiting the spray arrangement of 0 to 85° relative to the exit direction.

In other embodiments, the deflection arrangement can have a plurality of deflection tongues. Each outlet (e.g., nozzle) can be assigned a deflection tongue. The exiting and deflected or fanned out media flows can overlap in sections, where overall, a “curtain” can also be formed.

In other embodiments, outlets can be designed as holes in the spray arrangement, and/or the outlets can be nozzles, in particular two-fluid nozzles and/or tongue nozzles. The formation of outlets as holes allows for individual and simple design. For example, holes can be introduced into a ring that has a common supply line (reservoir) for a medium. The arrangement and design of the openings (diameter, cross-section, exit angle and orientation relative to an opposite spray surface) can be specifically adjusted. Tongue nozzles have the advantage that they allow a fanning out of an exiting media flow.

In further embodiments, the mold body can have a stripping lip in the edge section. Such a stripping lip enables, for example, scraping off protruding fibers when closing the pre-pressing tool of a pre-pressing station, where a pre-pressing tool with at least one pre-pressing body and a suction tool with at least one suction body are moved relative to each other. As the distance between the suction body and the pre-pressing body decreases, for example a circumferential stripping lip, which can include a flexible material (e.g., silicone), can come into contact with the edge section of the suction body in the edge section. Any remaining fibers that protrude beyond the edge section of a suction surface of the suction body after spraying are scraped off, and the edge of the fiber mat is pressed. A suction tool usually has a suction surface with a plurality of openings by which the fibers and liquid of a pulp are suctioned. The suctioned liquid is discharged via channels in the suction tool. In the edge section, a ring surrounds the suction surface, where the inside of the ring defines the outer edge of the fiber mat/preform and accordingly of the product to be produced. The stripping lip can have an outer diameter that substantially corresponds to the inner diameter of the ring so that the stripping lip can dip into the ring and scrape off the fibers as well as press the edge of the fiber mat. To facilitate the “dipping” of the stripping lip into the ring, the ring can have a dipping section with a larger diameter. The stripping lip can have a varying diameter at its outer edge with respect to the closing direction, which supports the scraping off and pressing of fibers. In other embodiments, the height of the stripping lip can be at least as large as the height of a ring in the closing or pressing direction.

In other embodiments, the tool can be a pre-pressing tool for pressing three-dimensional preforms or suctioned fibers/fiber mats made of a fiber-containing material and the mold body can be a pre-pressing body, where the three-dimensional surface is a pressing surface of the pre-pressing body, and where the pre-pressing body includes a flexible material (e.g., silicone or silicone-containing plastic mixture).

In other embodiments, the tool can be a suction tool for suctioning fibers from a fiber-containing suspension, and the mold body can be a suction body, where the three-dimensional surface is a suction surface of the suction body.

The above-mentioned object is also achieved by a molding plant for manufacturing fiber-containing products, having a pre-pressing station for pressing three-dimensional preforms made of a fiber-containing material with at least one pre-pressing tool and a suction station with at least one suction tool, where at least one spray arrangement is arranged on the at least one pre-pressing tool or the at least one suction tool, and outlets of the at least one spray arrangement are aligned with an edge section of the at least one opposite suction tool or the at least one opposite pre-pressing tool.

A molding plant with an integrated spray arrangement in a tool (suction tool or pre-pressing tool) offers the above-described advantages and enables faster processing by shortening the cycle time because spraying takes place during the closing of a suction tool and a pre-pressing tool. In the prior art, spraying is carried out as a separate process step before closing opposing tools that requires cycle time. Furthermore, the integration of the spray arrangement offers optimal alignment and spraying of fibers since there is no overspray of points that are not needed (e.g., underside of the carrier plate tool and fiber mat outside the edge section). In addition, the outlets of a spray arrangement can be specifically aligned and designed to the design of suction bodies and individually to products without compromise solutions.

In other embodiments, a molding plant can have at least one pre-pressing tool that is designed according to one of the above embodiments, or at least one suction tool that is designed according to one of the above embodiments.

In other embodiments, a molding plant can have a device for supplying media, which has at least one actuator for controlling the supply of media to the at least one spray arrangement, where the at least one actuator is arranged directly in front of a reservoir for providing a medium within the spray arrangement and/or directly in front of openings of the spray arrangement. The actuator can be, for example, a valve, a motor, a throttle valve, etc. The immediate arrangement of the actuator in front of a reservoir or the openings of the outlets of the spray arrangement allows a rapid response of the outlets to deliver a media flow. In addition, this can make controlling the actuator easier.

In other embodiments, the suction surface of the suction body and suction channels in the edge section for suctioning fibers can have different permeabilities for a reduced suction effect compared to the rest of the suction body. The different permeability can be achieved by a different design and distribution of openings in the suction surface (e.g., a mesh structure of a suction tool that rests on a suction surface of a suction body, where the suction body has suction channels). For example, the edge section of a suction surface in particular can have a smaller number of openings and/or a smaller opening width as well as different cross-sections at the openings than the remaining area of a suction surface so that overall fewer fibers are suctioned in the edge section, and there is also less protruding and excess fiber material. The section in which fewer fibers are suctioned can explicitly refer only to an outer edge section so that the edge of a product to be formed does not necessarily have to be thinner than the remaining area of the product.

The above-mentioned object is also achieved by a method for manufacturing fiber-containing products having a pre-pressing station for pressing three-dimensional preforms made of a fiber-containing material with at least one pre-pressing tool and a suction station with at least one suction tool, where at least one spray arrangement is arranged on the at least one pre-pressing tool or the at least one suction tool, and outlets of the at least one spray arrangement are aligned with an edge section of a suction body of the at least one opposite suction tool or a pre-pressing body of the at least one opposite pre-pressing tool, where a medium (media flow) is cyclically dispensed via the outlets in accordance with a control via an actuator when the distance between the suction surface of the suction tool and the pressing surface of the pre-pressing tool reaches a value between 1 and 30 mm.

The spraying of the fibers in the edge section of an opposing tool already takes place before the surfaces of the opposing tools touch each other. In particular, the delivery of a medium via the outlets (e.g., nozzles) can also be terminated before the surfaces of the opposing tools touch each other. The distance between the tools allows the edge section of an opposing tool to be exposed to a uniform media flow, where the influence of overlaps of the media flows of adjacent outlets, especially in the case of fan-shaped media flows, on the overall media flow is low.

In other embodiments, the media flow can be dispensed as a flat jet.

In other embodiments, the relative pressure for providing the media flow can be between 0.1 and 10 bar, preferably between 1 and 3 bar.

In other embodiments, the media flow can be dispensed for a period of 0.5 to 5 seconds in accordance with a relative movement of the pressing surface of the pre-pressing body of the at least one pre-pressing tool and the suction surface of the suction body of the at least one suction tool. In other embodiments, the duration and pressure of the media flow output is determined according to the distance between opposing surfaces of the involved tools.

The solution presented here enables material savings in the manufacture of products made of a fiber-containing material since only as much material (fibers) is suctioned at the edge as is actually needed. Moreover, a faster manufacturing method is provided since no interruption/waiting time is required as is necessary with classic prior art spray bars. Furthermore, less water is used because the spraying is targeted. Furthermore, there is no contamination of a molding plant or dilution of the pulp by spray water bouncing or dripping off as in the prior art when using spray bars. In addition, punching is no longer required since perfect edge quality is provided. Finally, a stable edge is provided since the edge is shaped, that is, the fibers in the edge are bound while a punch creates “angel hair” (loose fibers).

Further features, embodiments and advantages result from the following illustration of exemplary embodiments with reference to the figures.

Various 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 that are not essential to the technical teachings disclosed herein or that are obvious to a person skilled in the art are not explicitly reproduced. Features specified in the singular also include the plural unless explicitly stated otherwise. This applies in particular to statements such as “a” or “one.” The exemplary embodiments shown here do not represent any restriction with regard to further embodiments and modifications of the described embodiments.

shows a schematic representation of a molding plantfor manufacturing three-dimensional products from a fiber material, according to some embodiments. The fiber material for production can be provided by a fiber processing plant and made available to the molding plant. The provision and the making available can for example take place via supply lines, in which liquid pulp is fed from a fiber preparation plant to a storage container or pulp tankof the molding plant, for example continuously or discontinuously. Alternatively, pulp can be prepared in a pulp tankof the molding plant. For this purpose, for example, water and fibrous materials and, if necessary, additives can be introduced into a pulp tankvia a liquid supply, and the pulp can be treated in the pulp tankby mixing the individual components under heat input and by auxiliary means, such as an agitator.

Pulp refers to an aqueous solution containing fibers, where the fiber content of the aqueous solution can be in a range of 0.5 to 10 wt. %. In addition, additives such as starch, chemical additives, wax, etc. can be present. The fibers can be, for example, natural fibers, such as cellulose fibers, or fibers from a fiber-containing original material (for example waste paper).

The molding plantcan be used to produce, for example, biodegradable cups, 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 molding plantshown inhas a framethat can be surrounded by a cladding. The supply unitsof the molding plantinclude, for example, interfaces for the supply of media (for example, water, pulp, compressed air, gas, etc.) and energy (power supply), a central control unit, at least one suction device, line systems for the various media, pumps, valves, lines, sensors, measuring devices, a bus system, etc., and interfaces for bidirectional communication via a wired and/or wireless data connection. Instead of a wired data connection, there can also be a data connection via a fiber optic line. The data connection can be, for example, between the control unitand a central controller for multiple molding plants, to a fiber preparation plant, to a service point, and/or subsequent devices. It is also possible to control the molding plantvia a bidirectional data connection via a mobile device, such as a smartphone, tablet computer, or the like.

The control unitis in bidirectional communication with an HMI panelvia

a bus system or a data connection. The HMI (human-machine interface) panelhas a display that displays operating data and states of the molding plantfor selectable components or the entire molding plant. The display can be designed as a touch display so that adjustments can be made manually by an operator of the molding plant. 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. In this way, settings can be changed and the operation of the molding plantcan be influenced.