Method, casting mold and production device

Abstract

The invention relates to a method and a casting mould for producing a fibrous blank made of pulp (40). The method comprises the following steps: providing a casting mold; filling the casting mould with a process liquid in such a way that a liquid reserve (31) is formed in the casting mould; and applying the pulp (40) to the liquid reservoir (31) in the casting mould.

Description

Technical Field

[0001] The invention relates to a method for producing a fibrous blank made of paper pulp, in particular a method for producing a container or a fibrous closure element for a container, a casting mold for producing a fibrous blank made of paper pulp and a production device comprising a casting mold according to the preamble of the independent claim. Background Art

[0002] WO 2012 / 139590 A1 proposes a fibrous container. To produce such a container, so-called pulp is injected into an inverted mold by jetting, and a flexible balloon in the mold presses the pulp against the corresponding mold wall and compresses it accordingly. In the process, the pulp is compressed and heated to about 180° C. in order to dry the container.

[0003] Pulp is a mixture of fibers and water, in particular natural fibers such as hemp, cellulose or flax or mixtures thereof. If necessary, the pulp has additives which, for example, improve the hardening of the compressed pulp or influence the subsequent appearance or generally change the properties of the pulp or the subsequent container.

[0004] Since the pulp consists of different components with potentially different properties, the spraying process is also very difficult to control. In particular, the type and amount of pulp deposits in the mold are largely random. The deposits can be deposited on the finished container with different properties, for example with different wall thicknesses and thus with different strengths, or with different surfaces. Summary of the invention

[0005] The object of the present invention is to eliminate at least one or several disadvantages of the prior art. In particular, a method and a casting mould should be provided which enable the deposition of pulp to be controlled and preferably regulated.

[0006] This object is achieved by the method and the device defined in the independent claims. Further embodiments are derived from the dependent claims.

[0007] The method for producing a fibrous blank made of pulp according to the invention comprises the following steps:

[0008] - providing a casting mold;

[0009] - filling the casting mold with a process liquid, in particular water, so that a liquid reserve is formed in the casting mold;

[0010] - The pulp is applied to the liquid reserve in the casting mould.

[0011] By filling the casting mould with process liquid, specific process conditions can be created in the casting mould. The liquid reserve provides a static liquid column which is substantially free of turbulence and / or eddies.

[0012] By applying pulp to the liquid reserve, two media with similar properties are combined. If water is used as process liquid, for example, the liquid reserve also consists of water. And pulp is also essentially a water-based mixture. That is, if pulp is applied to the liquid reserve, the two media do not mix with each other. The liquid reserve is actually filled with pulp. That is, the liquid reserve provides a static liquid column, and applying pulp to this water column only prolongs it.

[0013] Typically, the fibrous blank casting mold is permeable to liquid and has two mold halves that can be separated from each other. The two mold halves provide a mold cavity that is filled with pulp. For example, the casting mold can be designed simply as a metal mesh, which has an outer boundary that is impermeable to liquid, so that a liquid reserve can be provided inside the casting mold. For example, the outer boundary can be simply realized by a container, wherein the container can be filled.

[0014] The mold cavity corresponds essentially to the negative image of the blank to be produced and, like the blank, has a corresponding pouring opening. The pulp is accordingly filled through the pouring opening. For bottle-shaped containers, the pouring opening is a pouring opening at the neck of the bottle. However, the blank can also be, for example, a container that is open upwards without a specific opening, such as a plate, a cup or a tray. These containers have an opening that, in normal use, is mostly facing upwards. Accordingly, the pulp is poured in through the opening cross section corresponding to the opening. However, for such wide-necked containers (e.g. cups), it is also possible to design the casting mold to be closed with a lid in the area of ​​the opening and to design a separate pouring opening here for pouring the pulp into the casting mold.

[0015] After the pulp has been applied to the liquid reserve, the liquid reserve can be replaced by draining the liquid reserve in a targeted manner through the casting mold. By draining the liquid reserve, the pulp flows into the casting mold.

[0016] The drainage process can be controlled by the excess pressure exerted on the pulp. Additionally or alternatively, it can be provided that the liquid reserve is removed in the casting mold by means of negative pressure, so that the pulp is sucked into the casting mold.

[0017] The discharge of the liquid reserve can also be controlled, for example, by means of a baffle, so that the discharge rate can be limited or regulated by limiting the discharge amount.

[0018] By draining the liquid reserve, in particular a flow of pulp can be generated within the casting mold, and the subsequent inflow of pulp can in the process be deposited on the inner wall of the casting mold, ie on the mold cavity.

[0019] As the pulp is deposited on the inner wall of the mold, the wall of the later blank will be formed. Through the control or regulation of pressure or volume as described above, the deposition process can be influenced and the formation of the wall can be influenced accordingly.

[0020] Additionally or alternatively, different pulps can be introduced into the casting mold in sequence. By injecting different pulps in this way, a layered structure of the blank can be formed in the casting mold. For example, pulps that differ in color or pulps that differ in properties, in particular fiber properties or functional properties (e.g. barrier properties) can be used.

[0021] Can be designed to discharge liquid storage from casting mold on a plurality of positions.At this, these positions can correspond to the blank later, then the different sections or the zone of corresponding casting mold.

[0022] By draining the liquid reserve at multiple locations, the flow of the pulp inside the mold can be directed, so that the deposition of the pulp can also be regulated and controlled. This allows the wall of the blank to be formed in a targeted manner and the amount and exact location of the precipitated or deposited pulp to be controlled in a targeted manner.

[0023] The deposition of pulp here refers in particular to the deposition of fibers in the pulp, specifically on the inner wall of the casting mold in the mold cavity.

[0024] It can be designed to drain the liquid reserve from the mold through multiple locations in a specific time sequence.

[0025] This allows the flow of the pulp to be precisely controlled and the fibers to be distributed in a targeted manner. Accordingly, the structure of the blank wall can be controlled in a targeted manner and a fiber distribution that meets specific requirements can be achieved in the blank wall.

[0026] For example, in areas subject to high forces, a thicker structure can be realized than in other parts of the blank. This makes it possible, for example, to realize container blanks which are optimized, for example, in terms of weight or stackability (top load) or fiber orientation. By means of targeted fiber deposition, it is possible to avoid large amounts of fiber being deposited in areas that are almost unloaded. This is not possible with conventional methods. Typically, the wall thickness of the blank and the wall thickness of the container always corresponds to the required wall thickness in order to withstand the maximum forces, and with the conventional methods used, it is not possible to control the fiber deposition process in a targeted manner.

[0027] The corresponding casting mold can be designed to have a plurality of discharge ports opened in a specific time sequence. The expression "discharge" here specifically refers to removing liquid from the casting mold.

[0028] Preferably, the pulp is injected into the casting mold with an overpressure, in particular after the pulp has been applied to the liquid reserve, ie during the draining of the liquid reserve. The pressure can in particular be built up before draining the liquid reserve.

[0029] By building up an overpressure, the flow of the pulp can be controlled more precisely.

[0030] Before the pulp is injected, the mold can be backwashed by filling it with process liquid. The process liquid can be discharged through the mold gate corresponding to the gate of the blank. This makes it possible to backwash the mold conveniently, wherein the backwashing liquid and the process liquid are preferably the same. Once the backwashing process has stopped, the mold has been filled with the aforementioned liquid reserve and pulp can be immediately applied to the liquid reserve.

[0031] This simplifies the entire process. Fibers still in the backwashing liquid have no negative impact and can at most be directly reused in the next step and deposited accordingly in the mold. Since no further process steps are required between backwashing and applying the pulp, this method is also comparatively faster.

[0032] Another aspect relates to a casting mold for producing a fibrous blank made of paper pulp, which is used in particular for implementing a production process for a fibrous blank made of paper pulp according to the method described herein. The casting mold is permeable to liquids and has at least one closable drain opening for draining liquid from the interior of the casting mold, in particular from a cavity. The casting mold has in particular a mold cavity that is permeable to liquids.

[0033] By means of the closable drain opening, it is possible to provide a liquid reserve within the casting mold and to build up pressure there, since the casting mold can be closed by means of the drain opening. Furthermore, if the liquid reserve located in the casting mold is replaced by pulp by draining, the drain opening enables a specific flow within the casting mold. By means of the correspondingly formed specific flow, the deposition of the fibers in the pulp can be controlled in a targeted manner.

[0034] Alternatively, the casting mold can also be designed to have a plurality of closable discharge openings, so that the liquid can be discharged from the interior of the casting mold at a plurality of locations.

[0035] As described, a specific distribution of the pulp can be achieved by means of a plurality of discharge openings, i.e. the fibers in the pulp are forced to settle in a specific manner within the casting mold. This allows a specific and targeted structure of the container wall. By opening or closing individual discharge openings in a targeted manner, it is possible in particular to change the flow within the casting mold and to direct the flow in a chronological order to different locations or sections of the casting mold.

[0036] From the opening of the blank to the bottom of the blank, each discharge port can be arranged at a corresponding position of the mold at different heights in this direction. In addition, the discharge ports can be distributed on the circumference of the blank. In this way, for example, multiple discharge levels can be achieved.

[0037] The closable outlet openings can be designed as valves, in particular squeeze valves. On the one hand, this allows targeted opening and closing of the outlet openings, and on the other hand, by varying the flow rate, the volume discharged through the corresponding outlet opening can be controlled. In this way, the flow direction and the flow rate can be directly influenced.

[0038] As mentioned above, the casting mold has an outer limit structure that is impermeable to liquid. In this way, the discharge ports can be arranged in the outer limit structure so that specific flow enhancement locations are achieved on the casting mold. These locations are where the discharge ports are located.

[0039] A further aspect relates to a production device having a casting mold as described herein for producing a fibrous blank made of paper pulp, in particular a casting mold for producing a fibrous blank according to the method as described herein.

[0040] The production device preferably has a control device for controlling the discharge opening.

[0041] By providing a production device, a system that matches one another can be provided, in which all components are preset to one another. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The method according to the invention is explained on the basis of the schematic drawings, in which:

[0043] Figure 1 : a casting mold;

[0044] Figures 2A to 2E : various method steps;

[0045] Figure 3 : exemplarily shows other representative fibrous containers that can be produced by the method of the present invention;

[0046] Figure 4 A representative fibrous bottle cap that can be produced by the method of the present invention is shown by way of example. DETAILED DESCRIPTION

[0047] Figure 1 A casting mold 20 for a bottle-shaped container blank is shown. The casting mold 20 has two mold halves, wherein Figure 1 Only one half of the mold is shown in the figure. A mold cavity 22 is arranged inside the mold 20, which is surrounded by a liquid-impermeable outer boundary structure 23. The mold cavity 22 is permeable to liquids and is formed here by a metal mesh or screen. The liquid-impermeable outer boundary structure 23 has a cavity 24 in which the mold cavity 22 is arranged. The mold 20 has a plurality of drain ports 21. The drain ports 21 connect the outside of the mold 20 with the cavity 24. In addition, the mold 20 has an injection port 25 that directly opens into the interior of the mold cavity 22. The drain ports 21 are arranged at different heights so that different drainage levels can be defined.

[0048] Here according to Figure 1The illustration shown in defines the height position designations so that they are defined on the container in its intended state, ie upright with the outlet facing upwards and the container bottom facing downwards, wherein the container here stands upright on the container bottom.

[0049] Valves are arranged on both the injection port 25 and the discharge port 21 to close the corresponding openings.

[0050] As shown here, the filling opening 25 can have a flow divider 26 which is likewise closable.

[0051] exist Figures 2A to 2E The various method steps or process steps are shown in the accompanying drawings. Figure 1 A simplified cross section of the casting mold 20 is shown in FIG. Figure 2A As shown in FIG, the casting mold 20 is filled with process liquid 30, so that a liquid reserve 31 is formed inside the casting mold 20. The casting mold 20 is closed here, that is, the drain opening 21 is closed. The liquid reserve 31 completely fills the cavity 24 and also flows through and fills the mold cavity 22.

[0052] The casting mold 20 is connected to a corresponding material pool through an injection port 25, and the pulp 40 is located in the material pool. Figure 2A In FIG. 4 , the pulp 40 is applied to the liquid reservoir 31 in the casting mold 20. The diverter 26 on the injection port is closed.

[0053] Now, if Figure 2B As shown in the figure, the liquid reserve 31 is discharged from the casting mold 20 in a targeted manner, more precisely, in this case in the direction of the arrow P1 through the discharge openings 21 arranged at the top in this figure. For this purpose, these discharge openings are opened. Now, the pulp 40 flows into the interior of the mold cavity 22 through the injection opening 25. The fibers in the pulp 40 will remain in the interior of the casting mold 22, more precisely, on the inner wall of the mold cavity 22. This will form the wall 101 of the subsequent blank. In fact, the fibers will be filtered out of the pulp, and only the liquid part of the pulp will flow into the cavity 24. This is shown by the hatching that is different from the pulp 40. By opening or closing the discharge openings 21 accordingly, a corresponding flow can be set inside the casting mold 20 so that the fibers are deposited at the desired position or position in the mold cavity 22.

[0054] As soon as, for example, sufficient pulp has been deposited in the upper region, as shown here, the now open discharge opening 21 can be closed and the other discharge openings 21 opened. Figure 2C Here, relative to Figure 2BThe drain port 21 shown opened in FIG. 2 opens the drain port 21 located further down. The process liquid 30 now flows out of the mold in the direction of arrow P2, and the pulp 40 is deposited at other locations in the mold cavity 22. The wall 101 will continue to form. Next, the drain port 21 located at the bottom can be opened. This Figure 2D . Now, the process liquid 30 still remaining in the casting mold 20 will be completely squeezed out by the pulp 40 and flows in the direction of the arrow P3. The structure of the wall 101 of the blank 100 is now complete.

[0055] Next, the valve at the injection port 25 is closed so that no more pulp can flow in. The liquid still remaining in the mold 20 is completely drained and the formed blank 100 is demoulded. The mold 20 is now empty, wherein fiber residues from the pulp 40 may still adhere to the mold cavity 22. These fiber residues can be backwashed. In the process, process liquid 30 is injected into the mold 20 through the drain port 21. This is done in Figure 2E The fiber residues are released from the mold cavity 22 by injecting process liquid and discharged via the diverter 26, as indicated by arrow P5. For this purpose, the injection opening 25 is closed and the diverter 26 is opened. This prevents process liquid from being flushed into the stock pool. After a period of time, the discharge opening 21 is closed and the flushing process is finished. At this point, Figure 2A As shown in FIG, the interior of the casting mold, namely the cavity 24 and the mold cavity 22, is refilled with process liquid 30. The diverter 26 can be closed and new pulp is applied to the liquid reserve by opening the injection valve 25.

[0056] Figure 3 Other representative fibrous containers that can be produced using the methods described herein are shown as examples. Figure 1 The container 100 is consistent with the container 100 described in 2. The container 100 is also bottle-shaped and has additional threads at the neck. The container 100' is disc-shaped, and the container 100" is cup-shaped.

[0057] Figure 4 A representative bottle cap 300 that can be produced using the method described herein is shown by way of example.

Claims

1. A method for producing a fibrous blank made of pulp (40), in particular a container (100, 100', 100") or a fibrous closing element (300) of said container (100, 100', 100"), comprising the following steps - providing a casting mold (20); - filling the casting mold (20) with a process liquid (30), in particular water, so that a liquid reserve (31) is formed in the casting mold (20); - Applying the paper pulp (40) to the liquid reserve (31) in the casting mold (20).

2. The method according to claim 1, characterized in that: After the paper stock (40) has been applied to the liquid reserve (31), the liquid reserve (31) is replaced by draining the liquid reserve (31) in a targeted manner through the casting mold (20).

3. The method according to claim 2, characterized in that The flow of the pulp (40) is generated by draining the liquid reserve (31), and in the process the subsequent inflow of pulp is deposited on the inner wall of the casting mold (20).

4. The method according to claim 2 or 3, characterized in that: The liquid reserve (31) is drained from the casting mold (20) at a plurality of locations.

5. The method according to claim 4, characterized in that The liquid reserve (30) is drained from the casting mold (20) through a plurality of locations in a specific time sequence.

6. The method according to any one of claims 2 to 5, characterized in that After replacing the liquid reserve (31), the container (100) formed by the deposition of the pulp (40) is removed from the casting mold (20).

7. The method according to any one of claims 1 to 6, characterized in that The pulp (40) is injected into the casting mold (20) using overpressure.

8. The method according to any one of claims 1 to 7, characterized in that Liquid reserves are removed in the casting mold (20) by means of negative pressure, so that the pulp (40) is sucked into the casting mold (20).

9. The method according to any one of claims 1 to 8, characterized in that Different pulps are injected into the casting mold (20) in sequence, so that a layered structure of the blank can be formed in the casting mold.

10. The method according to any one of claims 1 to 9, characterized in that By filling the casting mould (20) with the process liquid (30), the casting mould (20) is backwashed before injecting the paper pulp (40).

11. A casting mold (20) for producing a fibrous blank made of pulp (40), in particular for carrying out a method according to any one of claims 1 to 10, wherein: The casting mold (20) is permeable to liquids and is characterized in that the casting mold has at least one drain opening (21) which is closable and allows draining of liquid from the interior (22) of the casting mold (20).

12. The casting mold (20) according to claim 11, characterized in that The casting mold has a plurality of closable drain openings (21), so that liquid can be drained from the interior of the casting mold (20), in particular from the cavity (24), at a plurality of locations.

13. The casting mold (20) according to claim 12, characterized in that The plurality of closable discharge openings (21) are arranged at different levels along the casting mold (20).

14. The casting mold (20) according to any one of claims 11 to 13, characterized in that The closable outlet opening (21) is designed as a valve, in particular a squeeze valve.

15. The casting mold (20) according to any one of claims 11 to 14, characterized in that The casting mold has an outer limit structure (23) which is impermeable to liquid.

16. A production device comprising a casting mould (20) for producing a fibrous container (100) made of pulp (40) according to claims 11 to 15, in particular produced according to the method according to claims 1 to 9.

17. The production device according to claim 16, characterized in that The production device has a control device for controlling the discharge port (21).

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