METHOD AND DEVICE FOR PRODUCE A FIBER MOLDED BODY

Abstract

Method for producing a shaped body (10) from fibrous material, comprising the following process steps: - Suction of a fibrous fluid mixture with a suction form (1) having a porous wall (8, 9) to create a fibrous layer on the wall; - Compacting the fiber layer to form the molded body (10); - Drying of the molded body (10); where the wall (8, 9) of the suction mold (1) has a plurality of wall sections (A, B), wherein fiber material is drawn in through at least two of the wall sections (A, B) for different suction durations, so that sections of the fiber layer of different thicknesses are formed on these wall sections (A, B), characterized in that fiber material is drawn in through a first wall section (A) during a first suction period and fiber material is drawn in through a second wall section (B) during a second suction period, wherein the second suction period is shorter than the first suction period and wherein at least the drawing in through the second wall section (B) is timed so that the total suction period (T) is divided into several suction intervals which are interrupted by pauses, and wherein no drawing in through the second wall section (B) takes place during the pauses.

Description

Technical field

[0001] The invention relates to a method and a device for producing a shaped body from fibrous material. State of the art

[0002] Fiber molded parts are used for various purposes, particularly as transport packaging and for protecting sensitive goods. For example, fiber molded parts serve as an alternative to plastic trays, as molded inserts in packaging, and as food packaging. Increasingly, everyday items (e.g., drinking containers) are also being manufactured from fiber molds.

[0003] It is known to produce fiber-based molded bodies by drawing a mixture of fibrous material and a fluid through a suction mold having a porous wall. Fibrous material—also referred to as fiber stock—is a quantity of fibers, often formed from cellulose. In the known process, the shape of the wall is complementary to the contour of the fiber-based molded body to be produced, and the pores in the wall are generally smaller than the fibers. Thus, when the fibrous-fluid mixture is drawn through the suction mold, only the fluid of the fibrous-fluid mixture is drawn through the wall of the suction mold, while the fibers are deposited on the wall of the suction mold. The fiber content is increased and compacted on the wall of the suction mold during the drawing-in process.After a specific suction period, the fiber material is compressed into a layer against the mold wall by the suction of the fiber-fluid mixture, resulting in a fiber-molded body with the desired contour and wall thickness. If necessary, the fiber-molded body is reshaped (pressed) and dried after demolding from the suction mold.

[0004] A well-established process based on the above principle is fiber casting. In this process, a suction mold with a porous wall is immersed in a fiber-water mixture – also known as pulp or fiber slurry. The suction of the pulp creates a fiber-based body with a high water content on the porous wall. After demolding, the fiber-based body is further dried, increasing the dry matter content and thus solidifying it.

[0005] The described, known manufacturing process can be used to produce fiber-shaped bodies with complex contours that correspond to the contours of the porous walls of the suction mold. The wall thickness of such fiber-shaped bodies is essentially the same along the entire contour. In other words, these fiber-shaped bodies consist of a layer of fiber material with a substantially uniform thickness.

[0006] It has been shown that for certain applications of molded fiber bodies, it can be advantageous for a molded fiber body to have a fiber layer with multiple sections of varying wall thicknesses. For example, the fiber layer of a molded fiber body can be thicker in a localized section than in other sections, thus providing mechanical reinforcement. Similarly, a molded fiber body can have a locally restricted section with a reduced wall thickness in areas subject to low mechanical stress. This allows for material and weight savings in the molded fiber body.

[0007] Fiber-reinforced molded bodies with wall sections of varying thicknesses and manufacturing processes for such fiber-reinforced molded bodies are known in the prior art. For example, JP 2001-106220 A discloses a fiber-reinforced molded body and a manufacturing process in which a fibrous bottle is produced by the fiber casting process described above. In an additional process step, an upper section of the fibrous layer from which the bottle is formed is compressed vertically in the suction mold in the area of ​​an upward-facing bottle opening while still wet, using a movable plug. This locally increases the thickness of the fibrous layer in this area. Furthermore, an expandable core arranged on the plug is inserted through the opening into the bottle and expanded to compact the wet fiber-reinforced molded body. After compaction, the fiber-reinforced bottle is demolded from the suction mold and dried.

[0008] From JP 2001-032200 A, a fiber-molded bottle that is easily foldable for disposal purposes and a manufacturing process for this fiber-molded bottle are known. The easy foldability is achieved by having a reduction in the thickness of the fiber layer of the fiber-molded bottle on the inside of the bottle. The fiber-molded bottle is manufactured essentially according to the fiber casting process described above. Additionally, the wall through which the fiber-water mixture is drawn in is lined with cellophane tape or similar material in areas where sections of the fiber-molded bottle with reduced wall thickness are produced. Due to the cellophane tape, the amount of fiber deposited in these areas is less than in other, unlined sections of the wall. As a result, the wall thickness of the formed fiber-molded body is reduced in the lined sections compared to other sections of the fiber-molded body.

[0009] From JP 2004-183135 A, another fiber-shaped body and a further method for its production are known. The fiber-shaped body is intended to be particularly lightweight and to exhibit high strength. For this purpose, the fiber-shaped body has a section with a high wall thickness and a section with a low wall thickness. In the thin-walled section, as well as in the transition from the thin-walled to the thick-walled section, the density is higher than in the thick-walled section. The fiber-shaped body is produced essentially according to the fiber casting process described above, initially with a uniform wall thickness. In a further process step, the fiber-shaped body is pressed. The pressing process creates the thin-walled section and the high-density transition section.

[0010] Features of the method according to the preamble of claim 1 are evident from US 2001 / 0040016 A1 and DE 24 49 953.

[0011] The processes known from the prior art for producing fiber-shaped bodies with wall sections of different thicknesses are mostly complex because they include at least one additional process step compared to the known manufacturing processes for fiber-shaped bodies. Summary of the invention

[0012] The invention is based on the objective of providing a fast and technically simple method for producing fiber-reinforced molded bodies with stably bonded wall sections of varying wall thicknesses. A further objective is to provide a technically simple device for carrying out the method that can be flexibly adapted to different geometries of fiber-reinforced molded bodies.

[0013] According to the invention, this problem is solved by a method and by a device having the features of the independent claims. Advantageous embodiments are described in the dependent claims.

[0014] The process described here for manufacturing a shaped body from fibrous material comprises the following process steps: - Suction of a fiber-fluid mixture with a suction mold having a porous wall to create a fiber layer on the wall; - Compacting the fiber layer to form the molded body; - Drying of the molded body.

[0015] To solve the above problem, the wall of the suction mold has a plurality of wall sections. Fiber is drawn in through at least two of these wall sections for varying suction durations, resulting in fiber layer thicknesses being formed in these sections. In other words, the invention is based on the idea of ​​producing a fiber molded body with several wall sections of varying thicknesses by drawing in the fiber for different durations to create these different sections. This results in different amounts of fiber being accumulated in the respective wall sections to form a fiber layer, thus creating fiber layers of varying thickness.

[0016] In the process described here, the volumetric flow rate of the fiber-fluid mixture flowing through the porous wall is preferably essentially the same through all wall sections of the wall. The term volumetric flow rate refers to the volume of the fiber-fluid mixture flowing through a predetermined unit area of ​​the porous wall during a predetermined duration. The distribution of fiber in the fluid is preferably essentially homogeneous, so that with the same volumetric flow rate, the same amount of fiber is deposited to form a fiber layer at different locations within a section of the wall, and the density of the deposited fiber layer is essentially the same in all sections of the fiber layer. In the process described here, the suction time through the different wall sections of the suction mold, i.e.,The time during which the fiber-fluid mixture is drawn through the different sections of the porous wall varies. A long absorption time produces a thick-walled section of the fiber layer of a fiber molded body. A short absorption time produces a thin-walled section of the fiber layer of the fiber molded body.

[0017] The production of a fiber-based molded body using the method described here is particularly fast and simple. Unlike prior art solutions, neither a pre-process step (e.g., applying a cellophane band to locally reduce the flow rate) nor a post-process step (e.g., a pressing step to adjust the wall thickness) is required. Instead, the desired wall thickness of the different sections of a fiber-based molded body is achieved during the suction of the fiber-fluid mixture. To achieve this, it is sufficient to configure the suction mold, used for the production of fiber-based molded bodies preferably in series, only once such that different sections of the porous wall are subjected to negative pressure for varying suction durations, thus drawing in the fiber-fluid mixture.Following this initial setup of the suction mold, the fiber-based body is produced by drawing in a fiber-fluid mixture with varying wall thicknesses for different sections of time within the mold. As is known from the prior art, the deposited fiber layer on the mold wall is compacted during the suction process. Once the fiber-based body has formed on the porous wall of the mold, it is demolded with the desired wall thickness in the different sections of the fiber layer. The mold is then ready to produce another fiber-based body without requiring resetting. If necessary, the fiber-based body can be pressed and / or dried after demolding to increase its strength.

[0018] Fiber is drawn in through a first wall section during an initial suction period, and through a second wall section during a second suction period, which is shorter than the first. The suction through the second wall section is synchronized, so that the total suction period is divided into several suction intervals interrupted by pauses. No suction occurs through the second wall section during these pauses. This synchronized suction creates a stable connection between the wall sections with their different wall thicknesses, as explained in detail below.

[0019] In practice, the fiber-reinforced body can be impregnated with a biodegradable, cured impregnation that reinforces the fiber-reinforced body, at least locally. The impregnation can, for example, contain at least one of the following components: - Carnauba wax; - Beeswax; - Shellac; - Sugar cane wax.

[0020] Impregnation can increase the strength of fiber-reinforced molded parts. Fiber-reinforced molded parts typically contain pores into which moisture, water, or other liquids can penetrate. Fiber-reinforced molded parts usually have limited strength, especially when saturated with moisture. To increase the durability of the fiber-reinforced molded part, the pores can be sealed, at least in selected areas, with a hardening impregnation. In its hardened state, the impregnation can exhibit a higher strength than the fiber material from which the fiber-reinforced molded part is formed.

[0021] Additionally or alternatively, the fiber-shaped body can be coated with a coating solution. The coating solution can, for example, contain at least one of the following components: - Cellulose fibers; - Casein; - Whey; - Agar Agar; - Psyllium husks.

[0022] If the fiber-based molded part contains moisture, coating can take place, particularly after the moisture has been removed. Coating can be achieved by spraying a coating solution onto the fiber-based molded part in the suction mold, a compression mold, a counter-mold, and / or in a separate coating station. Additionally or alternatively, the fiber-based molded part can also be immersed in a coating solution, or it can be poured or rinsed with a coating solution. The coating can also be applied as a partial coating to only a portion of the fiber-based molded part's surface.

[0023] A coating can impart advantageous properties to the fiber-reinforced molded body. For example, a color layer or a water-repellent functional layer can be applied. The coating can also increase the density of the fiber-reinforced molded body and its resistance to moisture or aggressive substances. Finally, the coating can increase its strength.

[0024] In practice, the fiber-fluid mixture can be one of the following two alternatives: - a fiber-water mixture; - a fiber-air mixture.

[0025] The fluid of the fiber-fluid mixture can be water. In this case, the suction mold is immersed in a pulp, i.e., a mixture of water and fibers, according to known fiber casting processes, and the pulp is then drawn through the porous wall of the suction mold.

[0026] The inventor of the present invention proposed in the unpublished German patent application DE 10 2022 120 928.8 the use of a fiber-air mixture in which the fibers are deposited from a fluidized bed onto the porous wall of the suction mold. This eliminates the need for dewatering and drying. Here, too, a fiber layer with varying thicknesses can be created by using different sections of the suction mold wall through which suction is applied for different lengths of time.

[0027] In practice, the suction of the fiber-fluid mixture through all wall sections can begin and / or end simultaneously. In other words, the suction times for creating the different wall sections overlap at least partially. The different sections of the fiber layer are thus preferably formed not successively, but partially simultaneously. This results in stable bonding of the sections and a particularly fast manufacturing process. If the suction of the fiber-fluid mixture through all wall sections begins and ends simultaneously, the suction process can be interrupted by pauses in those wall sections of the suction mold through which fiber is drawn during shorter suction durations (hereinafter also referred to as pulsed suction or pulsed operation).For example, the maximum suction duration for producing the molded part—that is, the time at the first wall section of the suction mold through which fiber is drawn during the longest suction duration—can be divided into several equal intervals. The suction process at the wall sections of the suction mold through which fiber is drawn during shorter suction durations can be interrupted by pauses during some of these intervals, while suction through the first wall section continues uninterrupted. For instance, if suction occurs through a second wall section of the suction mold for only 50% of the maximum suction duration, the suction through this second wall section can be interrupted in every second interval. Similarly, the suction process can be interrupted by a pause at a wall section in every third interval of the maximum suction duration if this wall section is active for approximately...66% of the maximum suction time should be used.

[0028] In practice, each wall section can be assigned a suction line equipped with a valve. The suction line connects the wall section to a suction device for drawing in the fiber-fluid mixture. In the method described here, the valves for each suction line can be opened and closed at predetermined times to initiate suction through their assigned wall sections for the specified individual suction duration. When a valve of a suction line is in the open position, so that one of the wall sections is fluidly connected to the suction device via the suction line, the suction device draws in the fiber-fluid mixture through this wall section as intended. When the valve is in the closed position, suction through this wall section is interrupted.

[0029] The timed suction through those wall sections with shorter suction duration has the advantage that the thinner layers of fibrous material created in these wall sections are essentially connected over their entire thickness to the thicker fibrous layer of the adjacent wall section with greater thickness by interlocking fibers.

[0030] In practice, the fiber layer can be formed on the front side of the porous wall of the suction mold, and the fluid of the fiber-fluid mixture drawn in through the wall can be extracted from the rear side of the wall. A connection element for attaching one of the suction lines is arranged on at least one section of the rear side of the wall. This connection element is specifically designed as a chamber that can be pressurized with suction pressure and whose extent on the rear side of the suction mold wall essentially corresponds to the extent of the wall section. The edge of the chamber is tightly connected to the rear side of the suction mold wall. The suction line leads to the interior of the chamber and pressurizes it with the vacuum.When the suction device is activated and the valve in the suction line is open, the fiber-fluid mixture is drawn through the front face of the porous wall in the wall section defined by the chamber. As the fiber is deposited on the wall, the fluid flows through the pores in the wall into the chamber and from there through the suction line to the suction device. This chamber geometrically defines the section of the wall on the front face of the suction mold where a formed fiber layer has a predetermined, uniform thickness. Additional chambers can adjoin the rear face of further wall sections, allowing for different suction durations. These additional chambers are connected to further suction lines, which can be pressurized independently of the first chamber via their own valves.In this way, several wall sections can be formed on the front of the porous suction mold wall, through which suction is drawn for an individually defined suction duration, preferably by synchronized operation of the valves. Several chambers can also be connected to a common suction line and pressurized via a common valve, for example, when opposing sections of a split suction mold define a common section of the suction mold wall that is uniformly pressurized for a predetermined suction duration.

[0031] In practice, the suction mold can be a split suction mold with a wall section designed as an opening section for producing a hollow body with an opening. In the area of ​​the opening section of the suction mold, the fiber-fluid mixture can be drawn in for a longer suction duration than through at least one other wall section of the suction mold. The split suction mold can be designed such that a fiber-shaped body in the form of a container, particularly a bottle or a crucible, is formed on the wall. On the annular wall section designed as the opening section, a bottle neck or mouth area, encompassing the opening of a bottle, is then produced, for example. A thread can be produced on the outside of a jacket-shaped section of the molded body in the area of ​​the opening. The section of the fiber layer that forms the bottle neck or mouth area...The section forming the threaded end has a greater wall thickness than other parts of the bottle, such as the body, due to the longer suction duration. This mechanically reinforces the area surrounding the opening of the container, allowing a closure element to be securely and tightly fitted to the container. In a two-part suction mold divided along a longitudinal plane to form a bottle or other container, the mouth area or neck is formed by each half of the mold. In this case, the first section of the closed suction mold, starting at the mouth of the container, can be enclosed by chambers on both mold parts. These chambers are connected to a first suction line and pressurized via a first valve.The sections of the two suction moldings located axially away from the mouth together form a second wall section that is subjected to negative pressure for a shorter period.

[0032] In practice, the suction mold can also be a split suction mold with a wall section designed as a bottom section for producing a hollow body with a bottom. In this case, the fiber-fluid mixture can be drawn in through the bottom section for a longer suction duration than through at least one other wall section of the suction mold. In this context, explicit reference is made to the variations and advantages described above in connection with the suction mold having an opening section. If the bottom of the hollow body has a greater wall thickness than, for example, the body of a bottle, an injection-molded part can be placed within the bottom.

[0033] In practice, a prefabricated element can be inserted into the suction mold. This element has a connecting section with openings that runs parallel to a first wall section of the suction mold. Such a method is known from WO 2022 / 258707 A1 of the applicant. The prefabricated element can, for example, be an injection-molded part made of a biodegradable thermoplastic. The connecting section can be thin-walled and have the form of an open lattice that extends parallel to and at a small distance from the first wall section of the suction mold. When the fiber material is drawn in, a layer of fibers is deposited on the first wall section. The deposited fibers protrude through the openings of the connecting section and embed the lattice-shaped connecting section in the resulting fiber layer.The fiber-fluid mixture is drawn in through the first wall section for a longer suction duration than through at least one other wall section of the mold. This creates a particularly stable fiber layer in the area of ​​the connection section, ensuring a strong bond with the connection section of the pre-molded element. The pre-molded element could, for example, be a mantle-shaped neck section with a screw thread made of biodegradable plastic in the case of a fiber container. In principle, any functional element with a grid-like connection section can be anchored in a wall section of the molded part in this way. The injection-molded part can, for example, provide mechanical reinforcement to a section of the molded part if it has a higher strength than the fiber material.Furthermore, the injection-molded part can preferably be made of biodegradable, compostable and / or water-soluble material.

[0034] The process can be implemented with a device for producing a shaped body from fibrous material, in accordance with the process aspects described above. The device comprises at least the following components: - a space for receiving a fiber-fluid mixture; - a suction mold with a porous wall; - a suction device.

[0035] The wall of the suction mold has a plurality of wall sections, each of which is associated with a suction line containing a valve, which connects the wall section to the suction device. The valves of at least two of the suction lines can be opened and closed independently of each other. The device can also have more than one suction device. In this case, each wall section can be associated with a suction line and a suction device, and the wall sections are each connected to the suction device via the valve, allowing flow through them. The porous wall of the suction mold can, in particular, have a three-dimensional contour with multiple wall sections. The porous wall of the suction mold can, for example, be formed by a metallic wire mesh.However, it can also be manufactured, for example, as a solid wall with an open-pore structure, a sponge-like structure, and / or with separate bores. The wall sections can be flat, convex, and / or concave. The suction mold can also have multiple wall sections, each forming a fiber-shaped body. In this way, a single suction mold can produce multiple fiber-shaped bodies. Here, too, the suction mold can consist of two parts with opposing recesses, which, when closed, form a cavity for creating a molded body. In this case, each recess can have several sections through which suction is applied for varying durations. Opposing sections of the two suction mold parts can be connected to the same suction lines and pressurized via the same valves.The corresponding wall sections of each wall area, i.e., each cavity, can be fluidically connected in such a way that they are simultaneously subjected to a vacuum. In other words, the chambers on the back side of identical sections of several cavities are connected in a form such that these identical wall sections of the cavities are each simultaneously subjected to a vacuum. Each cavity has at least one further wall section, and these further wall sections of the multiple cavities are also fluidically connected in such a way that they are simultaneously subjected to a vacuum.

[0036] In practice, the space that accommodates the fiber-fluid mixture can be one of the following two alternatives: - a chamber filled with a fiber-air mixture; - a basin filled with a mixture of fiber and water (pulp).

[0037] If the space is a chamber filled with a fiber-air mixture, the device can be used to produce a fiber-shaped body using the dry molding process described above. In this case, the suction mold, whose wall corresponds to the contour of the fiber-shaped body to be produced, can be positioned in the chamber. A fiber-air mixture can be introduced into the chamber, and the fiber-air mixture can be drawn in through the porous wall of the suction mold.

[0038] In practice, the porous wall of the suction mold can have a front and a back, with a connection element, in particular a chamber, arranged on at least one section of the back of the wall, which allows the connection of a suction line. In this context, reference is made to the above description of the corresponding method. Brief description of the drawings

[0039] Further practical embodiments and advantages of the invention are described below in connection with the drawings. Fig. Figure 1 shows an isometric representation of a suction mold for the production of a molded body made of fibrous material. Fig. 2 shows a top view of the suction mold made of Fig. 1. Fig. Figure 3 shows a front view of the suction mold from the Fig. 1 and Fig. 2. Fig. 4 shows one along the section line IV-IV in Fig. 3. Cutaway view of the suction form from the preceding figures. Fig. 5 shows one of the Fig. 1. Corresponding representation of the suction mold in the open state with two molded bodies formed in the suction mold. Fig. Figure 6 shows a cutaway side view of the opened suction mold made of Fig. 5. Fig. Figure 7 schematically shows the division of the total suction time into different intervals. Fig. Figure 8 shows a prefabricated element that fits into the suction mold made from the Fig. 1 - 6 can be inserted. Description of the embodiments

[0040] In the Fig. Figures 1 to 6 show a suction mold 1, which has two suction mold parts 2 and 3. The first suction mold part 2 is shown lying at the bottom in the drawings. The second suction mold part 3 lies on top of the first suction mold part 2. However, the position of the suction mold parts 2 and 3 is of secondary importance for the function of the suction mold 1.

[0041] The suction molded parts 2, 3 are attached to retaining elements 4, 5. The retaining elements 4, 5 are pivotally connected to each other via a joint 6. Due to the pivotable connection, the suction molded parts 2, 3 can be moved from the closed position ( Fig. 1-4) into an open position ( Fig. 5 and Fig. 6) and move back again.

[0042] As particularly in Fig. As can be seen in Figure 4, each suction molding 2, 3 has a hollow housing. In the closed state, the suction moldings 2, 3 form a bottle-shaped cavity 7. This cavity 7 is bounded in the lower region by a porous wall 8 of the first suction molding 2. In the upper region, the cavity 7 is bounded by a porous wall 9 of the second, upper suction molding 3. The porous walls 8, 9 can have a sieve-like structure and be inserted into the housings of the suction moldings 2, 3 or be part of the housings themselves. It is also known to manufacture the suction moldings, or at least the areas of the suction moldings with the porous wall 8, 9, by additive manufacturing, in which case the porous wall 8, 9 can be produced by 3D printing.

[0043] Both suction mold parts 2, 3 are designed as hollow bodies, forming at least one chamber on the side of the porous wall 8, 9 facing away from the cavity 7. In the Fig. 4 and Fig. Figure 6 schematically indicates, with dashed lines, that the two porous walls 8, 9 are divided into front sections A and rear sections B. The front sections A of the porous walls 8, 9 border the opening of a molded body 10, which is formed in the shape of a bottle by means of the suction mold 1. This molded body 10 is in the Fig. 5 and Fig. 6 to recognize.

[0044] The rear sections B of the porous walls 8, 9 extend over approximately 6 / 7 of the total length of the porous walls 8, 9. The rear sections B comprise the area of ​​the porous walls 8, 9 that defines the bottom of the molded body 10.

[0045] Again in the Fig. 4 and Fig. Figure 6 shows that a first suction line 11 is connected to a rear chamber 12 in the lower suction mold part 2. The suction pressure supplied to the rear chamber 12 via the first suction line 11 draws fiber material through the rear section B of the porous wall 8 of the lower suction mold part 2. A front chamber 14 is provided in the front region of the suction mold part 2, which can be pressurized with negative pressure via a second suction line 13. The front chamber 14 is formed by a partition 15 in the lower suction mold part 2.

[0046] The upper suction molding section 3 is designed according to the preceding description. A partition 16 separates a front chamber 17 in the upper suction molding section 3 from a rear chamber 18. The front chamber 17 extends over the front section A of the porous wall 9 and can be pressurized with a vacuum. The rear chamber 18, which extends over the rear section B of the porous wall 9, can also be pressurized with a vacuum via a suction line. The front chamber 17 in the upper suction molding section 3 is connected to the front chamber 14 in the lower suction molding section 2 via a fluid line (not shown), so that the same pressure prevails in both front chambers 14 and 17. The rear chamber 18 in the upper suction molding section 3 is connected to the rear chamber 12 in the lower suction molding section 2 via a fluid line (not shown), so that the same pressure prevails in both rear chambers 12 and 18.In this way, a vacuum is applied simultaneously and for the same suction duration in the lower suction mold part 2 and in the upper suction mold part 3.

[0047] The drawings show, in particular, the Fig. 2 and Fig. 3. It can be seen that the suction lines 11 and 13 connected to the lower suction molded part 2 are connected to a vacuum port 20 via a three-way valve 19. The three-way valve 19 can either direct the vacuum from the vacuum port 20 to both suction lines 11 and 13, or selectively shut off one or 13 of the suction lines, or shut off both suction lines 11 and 13. Fig. Figure 2 additionally shows schematically that the vacuum port 20 is connected via a vacuum line 21 to a pump 22, which forms a suction device for drawing in the fibrous pulp. The suction device 22 is not shown in the other figures for the sake of clarity.

[0048] The three-way valve 19 is shown schematically with a switch knob with which the three-way valve 19 can be manually switched. It is obvious to the expert that, for practical use, a hydraulically or electrically switchable three-way valve may alternatively be provided.

[0049] When the three-way valve 19 connects the suction line 13 to the vacuum port 20, allowing flow through it, the front chamber 14 of the lower suction mold part 2 is pressurized with vacuum, and fibrous material, for example from a pulp, is drawn in through the front wall section A of the porous wall 8 of the lower suction mold part 2. The fibrous material is then deposited on the front wall section A of the porous wall 8 near the neck of the molded body to be formed. When the suction mold 1 is closed, the front chamber 17 of the upper suction mold part 3 is fluidically connected to the front chamber 14 of the lower suction mold part 2 via the aforementioned fluid line (not shown), and the same pressure prevails in both front chambers 14, 17, so that when negative pressure is applied, fibrous material is deposited on the wall sections A of the porous walls 8 and 9 (and thus on the entire front wall section A of the suction mold 1).

[0050] When the three-way valve 19 connects the suction line 11 to the vacuum port 20, the rear chamber 12 of the lower suction mold 2 is pressurized with a vacuum, and fibrous material, for example from a pulp, is drawn in through the rear wall section B of the porous wall 8 of the lower suction mold 2. The fibrous material is then deposited on the rear wall section B of the porous wall 8, which borders the base of the molded body. When the suction mold 1 is closed, the rear chamber 18 of the upper suction mold 3 is fluidically connected to the rear chamber 12 of the lower suction mold 2, and the same pressure prevails in both rear chambers 12 and 18. Therefore, when a vacuum is applied, fibrous material is deposited on the wall sections B of the porous walls 8 and 9 (and thus on the entire rear wall section B of the suction mold 1).

[0051] The front wall section A of the porous walls 8, 9 can be subjected to a vacuum during a first suction period. The rear wall section B, near the bottom of the molded body 10, can be subjected to a vacuum during a second suction period, which is shorter than the first. The fiber layer deposited on the porous walls 8, 9 is therefore thinner in the region of the rear wall section B than in the region of the front wall section A. In this way, the molded body 10 can be formed from fibrous material with sufficient stability in the area of ​​the mechanically stressed connection with the neck of the container to be manufactured. In the area formed on wall section B, less stability is required, so a thinner container wall is sufficient here.

[0052] The Fig. Figure 7 schematically and exemplarily shows the circuit states of the three-way valve 19. The total suction duration T is divided into fifteen equal intervals. The number of intervals can, of course, be smaller or larger. The first two intervals are designated as intervals of type I1 and are shown as narrow rectangular strips without hatching. During each interval I1, both the suction line 11 leading to the rear chambers 12, 18 and the suction line 13 leading to the front chambers 14, 17 are fluidically connected to the vacuum port 20. In this way, a vacuum prevails in all chambers 12, 14, 17, 18, and fibrous material is drawn in through both the front wall sections A and the rear wall sections B, with the fibrous material being deposited on the front wall sections A and the rear wall sections B.

[0053] In the third interval, represented as type I2, only the suction line 13 is connected to the vacuum port 20. The suction line 11 is closed off by the three-way valve 19. In this type I2 interval, fibrous material is therefore only drawn in through the front chambers 14 and 17 and deposited on the front wall sections A. Each I2 interval pauses the suction process in the area of ​​the rear wall sections B, while suction is continuous in the area of ​​the front wall section A.

[0054] It is in Fig. Figure 7 shows that the first three intervals are followed by two intervals of type I1 and one interval of type I2. In this way, fiber is drawn in through the front chambers 14, 17 for the entire suction duration T. Fiber is drawn in through the rear chambers 12, 18 for a suction duration that corresponds to 2 / 3 of the suction duration T.

[0055] In Fig. Figure 8 shows a prefabricated element 23 that forms a thread for a closure cap. The element 23 can be prefabricated, for example, from a biodegradable thermoplastic or from a coated fiber material. It has a grid-like connecting section 24 with a multitude of openings 25. When fiber material is drawn in through the front wall section A, the fibers are deposited in the area of ​​the openings 25 of the connecting section 24 and securely embed it in the formed fiber layer. This connection achieves the required strength through the extended suction duration in the front wall section A, as described above.

[0056] The features of the invention disclosed in this description, in the drawings, and in the claims can be essential for realizing the invention in its various embodiments, both individually and in any combination. The invention is not limited to the described embodiments. It can be varied within the scope of the claims and taking into account the knowledge of the person skilled in the art. List of reference symbols 1 suction form 2 Suction molded part 3 Suction mold part 4 retaining elements 5 retaining element 6 joint 7 Cavity 8 porous wall 9 porous wall 10 molded bodies 11 first suction line 12 rear chamber 13 second suction line 14 anterior chamber 15 partition wall 16 Partition wall 17 anterior chamber 18 rear chamber 19 Three-way valve 20 Vacuum connection 21 Vacuum line 22 Suction device, pump 23 prefabricated elements 24 grid-shaped connecting section 25 Breakthrough A front wall section B rear wall section I1 first interval type I2 second interval type Total suction time

Claims

[1] Method for producing a shaped body (10) from fibrous material, comprising the following process steps: - Suction of a fibrous fluid mixture with a suction form (1) having a porous wall (8, 9) to create a fibrous layer on the wall; - Compacting the fiber layer to form the molded body (10); - Drying of the molded body (10); where the wall (8, 9) of the suction mold (1) has a plurality of wall sections (A, B), wherein fiber material is drawn in through at least two of the wall sections (A, B) for different suction durations, so that sections of the fiber layer of different thicknesses are formed on these wall sections (A, B), characterized by, that fiber material is drawn in through a first wall section (A) during a first suction period and fiber material is drawn in through a second wall section (B) during a second suction period, wherein the second suction period is shorter than the first suction period and wherein at least the drawing in through the second wall section (B) is timed so that the total suction period (T) is divided into several suction intervals which are interrupted by pauses, and wherein no drawing in through the second wall section (B) takes place during the pauses. [2] Method according to claim 1, characterized by that the fiber-fluid mixture is one of the following two alternatives: - a fiber-water mixture; - a fiber-air mixture. [3] Method according to one of claims 1 or 2, characterized by, that the suction of the fiber-fluid mixture through all wall sections (A, B) is started and / or ended simultaneously. [4] Method according to any of the preceding claims, characterized by , that each of the wall sections is assigned a suction line (11, 13) having a valve (19) which connects the wall section (A, B) to a suction device (22) for drawing in the fiber-fluid mixture, wherein the valve (19) is switchable between a closed position and an open position. [5] Method according to claim 4, characterized by , that the fiber layer is formed at a front of the wall and the fluid of the fiber-fluid mixture drawn in through the wall is drawn off from a rear of the wall, wherein a connection element for connecting one of the suction lines (11, 13) is arranged on at least one section of the rear of the wall. [6] Method according to any of the preceding claims, characterized by , that the suction mold (1) is a split suction mold (1) with a wall section designed as an opening section for producing a hollow body (10) having an opening, wherein in the area of ​​the opening section the fiber-fluid mixture is drawn in for a longer suction period than through at least one further wall section of the suction mold (1). [7] Method according to any of the preceding claims, characterized by , that the suction mold (1) is a split suction mold (1) with a wall section designed as a bottom section for producing a hollow body having a bottom, wherein in the area of ​​the bottom section the fiber-fluid mixture is drawn in for a longer suction period than through at least one further wall section of the suction mold (1). [8] Method according to any of the preceding claims, characterized by, that a prefabricated element (23) is inserted into the suction mold (1), which has a connecting section (24) running parallel to a first wall section of the suction mold (1) with openings (25), wherein the fiber-fluid mixture is drawn in through the first wall section (A) for a longer suction period than through at least one further wall section (B) of the suction mold (1) and wherein the fibers deposited on the first wall section (A) protrude through the openings (25) of the connecting section (24). [9] Device for producing a shaped body (10) from fibrous material according to a method according to one of the preceding claims, comprising: - a space for receiving a fiber-fluid mixture; - a suction form (1) with a porous wall (8,9); - a suction device (22); characterized by, that the wall of the suction mold (1) has a plurality of wall sections (A, B), wherein each of the wall sections (A, B) is assigned a suction line (11, 13) having a valve (19), wherein the valve (19) in an open position connects the wall section (A, B) to the suction device (22) and in a closed position interrupts the connection. [10] Device according to claim 9, characterized by that the room is one of the following two alternatives: - a chamber filled with a fiber-air mixture; - a basin filled with a mixture of fiber and water. [11] Device according to one of claims 9 or 10, characterized by , that the wall has a front and a back, wherein at least one section of the back of the wall (8, 9) has a connection element for connecting one of the suction lines (11, 13). [12] Device according to claim 11, characterized by , that the connecting element is a chamber (12, 14, 17, 18) which extends in the area of ​​the wall section (A, B) along the rear side of the wall section (A, B) and is connected to a suction line (11, 12). [13] Device according to any one of claims 9 to 12, characterized by , that the suction mold (1) is a split suction mold (1) with a wall section (A) designed as an opening section for producing a hollow body (10) having an opening. [14] Device according to any one of claims 9 to 13, characterized by , that the suction mold (1) is a split suction mold (1) with a wall section designed as a bottom section for producing a hollow body having a bottom.

Images