Press mold for filling fibrous blank and method for reducing water content of fibrous blank

Abstract

Disclosed is a press mold (20) for filling a fibrous blank, in particular a container (100, 100 ', 100' ') or a fibrous closure element (300) of said container (100), for use in a microwave cavity (40). The pressing die (20) can be penetrated by microwaves. When the pressing die (20) is in a closed state, at least one gap (21) is formed in the pressing die (20), and water can escape through the gap (21). In addition, the invention further discloses a method for reducing the water content of the fibrous blank.

Description

[0001] The invention relates to a pressing die for filling fibrous blanks, in particular a pressing die for filling containers or fibrous closing elements, and a method for reducing the moisture content of fibrous blanks, in particular a method for reducing the moisture content in a container or a fibrous closing element for a container according to the preamble of the independent claim.

[0002] WO 2012 / 139590 A1 discloses a fibrous blank in the form of a container. To produce such a container, so-called pulp is injected into an inverted mold and pressed against the corresponding wall layer by a flexible balloon in the mold and compressed accordingly. In the process, the pulp is compressed and heated to a temperature of about 180° C. in order to dry the container. It is also known to produce closure elements for containers from pulp.

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

[0004] The above method is time-consuming and requires a lot of energy. Therefore, it has been suggested to improve it. WO 2018 / 020219A1 discloses another method for drying wet fibrous blanks. The blank here also refers to a container. Here, the wet pulp is also compacted in the mold with a flexible balloon. Next, the container pre-processed in this way together with the balloon located therein is demolded and placed on a conveyor belt. The balloon is removed from the cold-formed container. Next, microwaves are applied to the container to dry it. Before drying, the blank is very sensitive to forces and must be handled with great care. During the drying process, the container may be deformed, for example due to uneven drying or due to inconsistent wall thickness, or the container may be damaged due to external influences.

[0005] The object of the present invention is to eliminate at least one disadvantage of the prior art. In particular, a device and a method are to be provided which make it possible to dry wet fibrous blanks, in particular containers such as bottles, cups, bowls or plates or wet fibrous closure elements, with low energy consumption and in the process ensure that they remain dimensionally stable.

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

[0007] The device according to the invention is realized by a pressing die for filling a fibrous blank. The fibrous blank can be in particular a container or a fibrous closing element for a container. The pressing die is designed to be used in a microwave cavity. For this purpose, the pressing die is microwave-permeable. In the closed state of the pressing die, at least one gap is formed inside the pressing die, through which moisture can escape.

[0008] By providing the fibrous blank with a microwave-transparent pressing mold, the wet fibrous blank can be kept in the mold during the drying process, i.e. during the application of microwaves. This protects the blank from external influences and avoids damage or deformation. By placing the wet fibrous blank in the microwave-transparent pressing mold, it is also achieved that the blank is exposed to microwaves on all sides and can then be dried on all sides. After this drying step, the moisture content of the wet fibrous blank is about 5% to 12%.

[0009] In the present method, the wet fibrous blank is usually formed according to methods known in the prior art. In other words, the pulp is poured into a porous mold or a solid mold with drainage channels, the input end of which is covered with a screen or has openings small enough to prevent the pulp fibers from penetrating, and the pulp fibers are deposited on the inner wall of the mold, thus forming a wall layer of the blank. Once the wall layer is thick enough, the alluvial deposition of the pulp is completed. The now semi-finished product, i.e. the wet fibrous blank, is removed from the mold and placed in a pressing mold, microwave-proofed so that it can be used in the pressing mold. At this point, the moisture content of the wet fibrous blank is about 75% or less, so that it can be transported between processing stations while maintaining a stable shape.

[0010] The wet fibrous blank is removed from the casting mold using a suitable transfer device. Next, the wet fibrous blank is placed in the open pressure mold. After placement, the pressure mold is closed. Preferably, the pressure mold is designed to consist of two parts. For removal and placement, it may be necessary to blow out and / or suck in the blank by means of negative pressure or overpressure. For this transfer operation, purely mechanical grippers can also be used.

[0011] Typically, the compression mold can have an inner wall which has a better surface quality than the inner wall of the casting mold.

[0012] Preferably, after the fibrous blank is prepared in the die, an expandable tool is placed into the fibrous blank. By expanding the expandable tool, the first step is to reduce the moisture content of the fibrous blank by compressing the wall layer of the blank. At this time, the moisture content of the wet fibrous blank is about 50% to 60%.

[0013] Through at least one gap in the die, the squeezed-out moisture (mainly water in this case) can escape from the die.

[0014] Accordingly, it is not necessary to design the die to be water-permeable. On the one hand, this allows the production of a die with a higher surface quality and, on the other hand, eliminates the need for tedious cleaning of possible die pores or channels after use of the die.

[0015] It is also possible to discharge water in a targeted manner through the gaps, or to select the area from which water is to be discharged in a targeted manner.

[0016] Through the gap, it is also possible to remove the water in a later step, i.e. during the application of microwaves. However, in this step, the water is usually present in the form of steam.

[0017] The gap as used herein refers to an opening having a long strip-shaped extension. In other words, the length of the opening is several times, in particular more than twenty times, the width. In addition, the gap is arranged in such a way that moisture can escape from the inside of the die, i.e. from the die cavity. In other words, the gap is an opening that provides a passage arranged radially relative to the longitudinal axis of the die.

[0018] Can be designed as, at least one gap is formed in a specific area of ​​the pressing die, this specific area corresponds to an area on the fibrous blank, this area can be removed before using the product made of the fibrous blank. Here, can be designed as to arrange other gaps on the pressing die.

[0019] In some cases, the gaps can leave machining marks on the blank surface. This does not pose any problem if the gaps are formed in areas that are later separated from the blank. Possible surface changes are therefore not visible in the finished product, as these areas are separated accordingly.

[0020] Here, it can be provided in particular that at least one gap is formed in a stamping area corresponding to the neck of the blank.

[0021] The neck of the blank can be designed to be correspondingly longer than the finished product, and the protruding part can be easily separated.

[0022] As mentioned above, the die can be designed to be composed of two or more parts. It has one or more die interfaces accordingly. Here, it can be designed to form a gap on at least one of the die interfaces. As mentioned above, as an alternative or additionally, the gap is arranged in the area that will be separated from the blank later.

[0023] By designing the gap at the mold interface, it is possible to easily process the gap because the tool can easily contact the mold interface during production. In addition, the gap located at the mold interface can be easily and efficiently cleaned.

[0024] If the die interface of the die extends in the same region as the die interface of the corresponding casting mold, the corresponding defective parts of the blank that appear after casting can be processed at the same position of the die. In this way, the blank does not need to bear unnecessary loads.

[0025] In particular, it can be designed that the gap is divided equally between the two elements of the mold interface. In other words, for a two-part mold, the two parts of the mold each account for half. However, it is also possible and conceivable to design the gap only on one of the two mold halves.

[0026] In other words, the two die halves do not touch in the cavity region, i.e. on the inner wall of the cavity, but are kept at a certain distance by a gap. In the radial direction outwards, the gap can widen and form a channel, which narrows again as the radial distance from the die center increases. The two die halves are then brought together one above the other, closing the channel. In other words, when the die is completely closed, the die interface forms a gap in the direction of the die interior.

[0027] Preferably, at least one gap is formed along the entire mold interface in the circumferential direction.

[0028] This increases the open cross section through which moisture can escape. Furthermore, by arranging the gaps over the entire mold interface, the entire blank is also essentially accessible from all sides. This is also advantageous because, due to the casting process, visible marks can form in this area of ​​the product. By arranging the gaps at the same position, additional machining marks can be avoided.

[0029] It is conceivable to design the stamp in the region of the container body as two parts and additionally have a separate integral shoulder region and / or a separate integral bottom region.

[0030] As mentioned above, at least one gap can lead to a moisture discharge channel, which is arranged in the wall layer of the die. In other words, the gap can extend and widen / increase towards the inside of the die, thereby forming a corresponding channel. Moisture can be discharged inside the moisture discharge channel.

[0031] By providing such a channel, it is ensured that even relatively large amounts of water can be discharged without blockages forming in the gap region. Through a corresponding channel, a forced flow can also be achieved to discharge the water.

[0032] The width of the at least one gap may be between 0.04 and 0.1 mm, in particular not more than 0.4 mm. The preferred width is between 0.6 mm and 0.25 mm.

[0033] On the one hand, such a value should be large enough to allow a corresponding amount of water to be discharged, but on the other hand, small enough to ensure that no marks are left on the fibrous blank.

[0034] The length of the gap is several times the width, preferably at least 20 times, more preferably 100 times. In particular, the gap extends along the die, preferably in the axial direction, i.e. in the longitudinal direction of the die or the fibrous blank formed therein, over a length of at least 25% of the inner contour.

[0035] Here, it can be designed to add additional openings or gaps in or on the die to drain water. In particular, for a specific blank geometry, in addition to the gaps on the die interface, it may be necessary or advantageous to drain water at other key locations.

[0036] The moisture discharge channel can be connected to a device that generates negative pressure or overpressure, so that a specific flow can be formed in the moisture discharge channel. In this way, moisture can be discharged more quickly and more specifically.

[0037] In addition, also can be designed to the fluid in this passage and carry out tempering and / or drying.If the corresponding temperature is designed in the passage, for example the temperature of raising, just can avoid as the steam of moisture condensation in the passage in the form of water.

[0038] Opening, for example directly connected to outside hole or passage, can be passed in the moisture discharge channel, so that can discharge moisture more quickly.In addition, corresponding passage also enables moisture to be discharged on the specific position of moisture discharge channel, thereby can accelerate moisture discharge in preferred regions.

[0039] The pressing die may have a substantially uniform wall thickness, which ensures that the microwaves can be applied substantially uniformly to the blank located in the pressing die, and that the microwaves act on the blank accordingly uniformly.

[0040] Additional support elements can be provided on the die to support the die. Typically, the die wall is relatively thin and / or at least partially made of elastic material. Deformation of the die can be avoided by corresponding support elements.

[0041] The microwave transparent stamp can be made from one of a range of materials, specifically including polyetherimide, polyimide, polyethylene, polyoxymethylene, polyetheretherketone, wood, polytetrafluoroethylene, ceramic, glass and polypropylene.

[0042] A method for reducing the moisture content in a fibrous blank according to the present invention, in particular a method for reducing the moisture content in a fibrous container or a fibrous container closure element, comprises the following steps:

[0043] - providing a wet fibrous blank in a die, in particular a die as described herein;

[0044] - placing an expandable tool into the wet fibrous blank;

[0045] - expanding the expandable tool, so that the squeezed-out water is discharged through at least one gap in the die by the expansion.

[0046] In this way, it is possible to discharge water from the blank in a targeted manner and to reduce the moisture content of the blank accordingly, so that the residual moisture content is below 15%, in particular between 6% and 12%.

[0047] Preferably, the fibrous blank is placed in a microwave-transparent pressing mould.

[0048] Preferably, microwaves are applied to the wet fibrous blank after being placed in the die.

[0049] The expandable tool may be designed to remain expanded during the application of microwaves.

[0050] The wall pressure on the wet fibrous blank can be maintained. In addition, by retaining the expandable tool in the wet fibrous blank, the blank is supported from the inside and accidental deformation is avoided. In addition, this can also improve the surface quality of the blank.

[0051] In particular, microwaves may be applied to the blank when pressure is applied to the expandable tool and the tool expands.

[0052] By applying microwaves, in particular the moisture in the fibers can be converted into a vapor phase, thereby enabling it to escape from the fibers. This vapor phase or gas phase is preferably discharged through at least one gap.

[0053] Here, it can be designed to discharge water by forced flow. By forced flow, the water discharge can be accelerated.

[0054] By means of the forced flow, in particular water can be discharged from the microwave cavity.

[0055] Additionally or alternatively, a moisture drainage channel can be designed in the die for this purpose, and at least one gap can be introduced into it. In this moisture drainage channel, flow can be generated by negative pressure or overpressure. By conveying moisture into the moisture drainage channel, it is possible to reliably avoid clogging of the moisture at the gap.

[0056] The blank portion that at least one die gap passes into can be separated from the blank after reducing the water content or reducing the moisture content. Accordingly, the traces formed can be removed from the finished product so that it has a uniform surface.

[0057] Openings, such as holes or channels directly connected to the outside, can lead to the moisture drainage channel to enable faster drainage of moisture. In addition, corresponding openings also allow moisture to be discharged at specific locations of the moisture drainage channel, thereby accelerating moisture drainage in preferred areas. As described herein, the channel can be formed in the area of ​​the mold interface.

[0058] Before the microwaves are applied, the fibrous blank can be placed in a microwave cavity which reflects the microwaves, in particular together with a pressing die.

[0059] This can enhance the effect of the microwaves. Microwaves that are not directly absorbed by the wet fibrous blanks are usually reflected on the inner walls of the microwave cavity, thereby increasing the probability that these microwaves hit the blanks that need to be dried.

[0060] It is well known that the excitation of microwaves can cause molecular vibrations, and heat is generated by such vibrations. For example, the natural frequency of water is 2.45 GHz. Therefore, microwaves are preferably generated at this frequency as well. In order to remove water or residual moisture from the wet fibrous blank, the water is preferably excited and heated until it evaporates and accordingly escapes from the wet blank.

[0061] In order to accelerate the drying process, it can be provided that the press mold and / or the microwave cavity are preheated to a temperature higher than 60° C., but preferably lower than 160° C.

[0062] This also prevents moisture escaping from the wet fibrous blank, in particular moisture escaping through gaps in the die, from condensing again in the immediate vicinity of the blank, for example inside the microwave cavity, and condensing in the form of droplets. Such condensation would lead to reduced efficiency, since this condensate would be continuously and repeatedly heated by the energy input.

[0063] For example, the heating or preheating of the die and / or the microwave cavity can be carried out by conventional resistance heating devices. Additionally or as an alternative, it can be considered to blow in a corresponding heated fluid, such as air, so that the components reach the required temperature.

[0064] An additional or alternative method for preheating the mold can also be that the mold itself absorbs the microwave radiation partially in a targeted manner, not more than 10%, preferably not more than 5%, or by discharging the steam energy generated during drying to the mold.

[0065] It can be designed to discharge moisture through strong exhaust. The moisture here can be water vapor, but it can also be liquid water.

[0066] If moisture drainage channels are provided on the pressure die, additionally or as an alternative, a strong exhaust air flow can also be formed in these channels.

[0067] By forced drainage, the moisture content inside the device can be kept low and condensation of moisture or reheating of moisture, for example heating of water droplets by microwave radiation, can be avoided or at least reduced.

[0068] In order to better dry and / or evaporate the moisture in the wet fibrous blank, it can also be designed to rotate the blank during the application of microwaves.

[0069] In this way, the energy input to the wet fibrous blank is more uniform and overheating of local locations of the blank can be avoided.

[0070] It can be designed to apply microwaves to multiple blanks at the same time. To this end, it can be designed to put multiple blanks, especially multiple pressing molds each having one blank, into the microwave cavity at the same time. This shortens the cycle time or increases the number of blanks dried per unit time, thereby improving the efficiency of microwave use.

[0071] The blanks can be rotated around their respective axes and / or around the same axis, which can improve the utilization efficiency of microwaves and input energy into the blanks more evenly.

[0072] Additionally or alternatively, it is also possible to design one or more dies that can simultaneously load a plurality of blanks. This simplifies the device because if the blanks are located in a multi-cavity die, each blank does not need to be handled individually.

[0073] A plurality of individual dies with blanks can be arranged in any spatial relationship to one another in the microwave cavity. This arrangement has no influence on the uniformity of the energy input.

[0074] Additionally or alternatively, it can be provided that a rotating element, a so-called stirrer, is arranged, in particular, inside the microwave cavity or at the transition from the waveguide to the microwave cavity and that the microwaves are swirled by means of this element. The stirrer can disrupt the static propagation of the microwaves in the drying chamber, i.e. the microwave cavity, and minimize the microwave regions with higher intensity.

[0075] Such an arrangement also has a positive effect on uniform energy input.

[0076] Another way to improve quality is to time the microwave application according to the moisture content of the wet fibrous blank. Timing can reduce power consumption. Usually, the moisture content in the wet fibrous blank is low near the end of the drying process, and too much energy may cause the blank to overheat in certain places. This can be avoided by reducing the power.

[0077] The die can be designed to be porous, or solid with channels for moisture drainage, or designed with a fine mesh material.

[0078] The method and the pressing die according to the invention are preferably used in combination with a device for reducing the water content in a fibrous blank, in particular in combination with a device for reducing the water content in a fibrous blank according to the invention. The device has a microwave cavity for placing a wet fibrous container and at least one device for generating microwaves. In addition, the device also has a device for feeding a medium into the microwave cavity and discharging a medium from the microwave cavity. In particular, this involves the feeding and discharging of compressed air and moisture.

[0079] One or more devices for feeding and draining a medium can be arranged, during use according to the invention, in connection with the moisture drainage channel of the die.

[0080] By means of such an input device and a discharge device, a specific airflow can be formed inside the microwave cavity, whereby moisture generated by applying microwaves and intruding into the microwave cavity or even into the moisture discharge channel can be discharged.

[0081] The device for generating microwaves can be connected to the microwave cavity by means of a waveguide.

[0082] By means of this connection, the device for generating microwaves can be arranged at a certain spatial distance from the microwave cavity, and the microwave radiation generated by the device can be introduced into the microwave cavity in a targeted manner.

[0083] Preferably, the waveguide has a rectangular cross section, wherein its longer side is generally oriented in the direction of the longitudinal axis of the microwave cavity. The longitudinal axis of the microwave cavity substantially coincides with the longitudinal axis of the fibrous blank or the container. The longitudinal axis is determined by the connection between the blank bottom and the blank or container gate.

[0084] It can be designed that a stirrer is arranged inside the microwave cavity, especially at the transition between the waveguide and the microwave cavity, and the microwaves are swirled by the stirrer.

[0085] Additionally or alternatively, openings connected to the microwave cavity can be arranged along the waveguide, and microwaves can propagate into the microwave cavity through these openings. This can reduce the structural size of the entire unit.

[0086] The device can have a cover plate for closing the microwave cavity. In this case, an exhaust opening can be arranged in the cover plate. Therefore, the opening is equivalent to a medium input and discharge device of the microwave cavity, in particular an input and discharge device for compressed air and moisture.

[0087] The cover plate can realize convenient sealing of the microwave cavity and accurate orientation of the exhaust port, so that a directional airflow can be generated in the device, that is, in the microwave cavity.

[0088] It can be designed to have multiple exhaust ports, which increases the capacity on the one hand and provides multiple airflows on the other.

[0089] Additionally or alternatively, the microwave cavity can be divided such that it consists of two identical housing parts or of housing parts of different size and shape.

[0090] Here, can be designed as each pressing die half mould is matched with the half cavity of a microwave cavity respectively. Here, each pressing die half mould can be connected together with the half cavity corresponding to the microwave cavity.

[0091] Additionally or alternatively, the microwave cavity can have a base plate. A large number of openings are arranged in the base plate for applying air to the microwave cavity. These openings thus act as a medium input and discharge device for the microwave cavity, in particular an input and discharge device for compressed air and moisture.

[0092] Such an opening can also be designed as an integral part of the die. In this case, the bottom plate of the microwave cavity can also constitute a component of the die, in particular the bottom plate of the die. Preferably, the bottom plate of the die ends in the microwave-proof tube. This can prevent microwaves from leaking out of the microwave cavity on the one hand, and on the other hand, simultaneously realize the discharge of moisture and / or the input of compressed air to form a forced flow.

[0093] The device for reducing the water content of the fiber container can be designed to have a plurality of devices for generating microwaves. Each of the plurality of devices for generating microwaves can be connected to the microwave cavity through a waveguide.

[0094] In this way, the various devices for generating microwaves can feed the generated microwave radiation into the microwave cavity at different locations. Each device can be controlled individually and emit microwave radiation at different powers. Accordingly, the drying of the blank can be carried out in a targeted manner, wherein, if necessary, microwaves can also be applied at different powers at different locations, so that the drying process can be carried out uniformly overall. In this case, uniform means that the wet fibrous container reaches a predetermined moisture content simultaneously over the entire container.

[0095] For this purpose, the waveguides may be arranged at different angles and / or at different heights along the longitudinal axis and / or the waveguides may have different orientations of the longer sides of their rectangular cross sections when arranged relative to the longitudinal axis.

[0096] Preferably, the device has a fixing device for the microwave-transmitting die. In this way, the microwave-transmitting die can be arranged and / or supported inside the device, especially the microwave cavity.

[0097] It can be designed to apply microwaves to multiple blanks at the same time. To this end, the device can be designed to have multiple fixing devices so as to fix multiple dies in the microwave cavity at the same time. This can shorten the cycle time and achieve more efficient use of microwaves.

[0098] The fixing devices can be respectively designed to rotate around respective axes and / or around the same axis. This can improve the utilization efficiency of microwaves and can input energy into the blank more evenly.

[0099] As an alternative, it is also possible to consider designing a fixture that can fix a plurality of pressing dies or a multi-cavity pressing die at the same time. This simplifies the device because if the pressing die is located in the microwave cavity, each pressing die does not need to be operated separately.

[0100] Here, the fixing device can also be designed so that it forms an effective connection with a corresponding supporting element on the pressure die, so that the pressure die is supported evenly and does not cause deformation thereof.

[0101] The blank can be configured as a container, in particular a bottle, a dish, a cup, a (coffee) capsule, a tray or a can. In addition, container closures can be processed by means of the method according to the invention and the device according to the invention.

[0102] A press die and a method for reducing the moisture content of a wet fibrous blank as well as a corresponding device are explained with the aid of schematic diagrams. In the drawings:

[0103] Figure 1 : shows a device having a die before microwave application;

[0104] Figure 2 : shows the period of microwave application Figure 1 The device shown;

[0105] Figure 3 : shows a perspective view of a die in an alternative device;

[0106] Figure 4 : shows a cross-sectional view of the die;

[0107] Figure 5 : shows a perspective view of an alternative die;

[0108] Figure 6 : shows a perspective view of an alternative die;

[0109] Figure 7 : shows a perspective view of an alternative die;

[0110] Figure 8 : Schematically shows other typical fibrous containers that can be produced using the method of the present invention;

[0111] Fig. 9 : A typical fibrous bottle cap that can be produced using the method described in the present invention is shown by way of example.

[0112] Figure 1 The device 200 for reducing the moisture content of a fibrous blank before applying microwaves is shown. In this example, the fibrous blank is a bottle-shaped container 100.

[0113] The device 200 has a microwave cavity 40 which is closed by a cover plate 41. An exhaust port 42 is provided in the cover plate 41, through which compressed air and / or moisture (e.g. water or water vapor) can be discharged. The microwave cavity 40 also has a bottom plate 43. A large number of openings 44 are arranged in the bottom plate, through which the supplied air can be introduced into the microwave cavity 40. The device 200 also has a device 50 for generating microwaves. In this example, the device 50 is designed as a magnetron. The device 50 for generating microwaves is connected to the microwave cavity 40 via a waveguide 51. The waveguide 51 is designed in a rectangular shape.

[0114] In the device 200, a die 20 is arranged in a microwave cavity 40. A wet fibrous container 100 is arranged inside the die 20. The container 100 has been taken out of a casting mold before being placed in the die 20, and the water content at this time is about 75%. After the wet fibrous container 100 is placed in the die 20, an expandable tool 30 is placed inside the wet fibrous container 100. Through the expansion of the expandable tool 30, the wall of the container 100 is pressed onto the inner wall of the die 20, and the water in the wet fibrous container 100 or the moisture therein is partially squeezed out therefrom. For this purpose, the die 20 is designed to be water-permeable. Water permeability can be achieved by porosity. In this example, various channels or openings in the form of gaps are designed in the die. Water can therefore be discharged through the gaps or openings on the demolding portion of the die. The discharged water or the discharged moisture is discharged at Figure 1 The water droplets are shown in simplified form in FIG. These water droplets can drip onto the bottom plate 43 of the microwave cavity and be discharged through the opening 44. After this step, the water content of the fibrous container 100 is about 50%.

[0115] Figure 2 The wet fibrous container 100 is shown during the application of microwaves. Figure 1 That is, Figure 2 The actual drying process is shown. Microwaves are generated in the device 50 for generating microwaves and are fed into the microwave cavity 40 via the waveguide 51. The water in the fibrous container 100 is heated by the microwaves, in other words, the molecules begin to vibrate. The water begins to evaporate and is discharged from the container 100 through the microwave-transparent die 20. Figure 2In the figure, the expandable tool 30 is shown in an unexpanded state, but the expandable tool 30 can also remain in an expanded state during the process shown here. The moisture shown here by the wavy lines enters the microwave cavity 40. In order to prevent this moisture from condensing in the microwave cavity 40, air is blown in through the opening 44 in the bottom plate 43 of the microwave cavity 40. The blown air flows out of the microwave cavity 40 through the exhaust port 42. In this way, an air flow is formed inside the microwave cavity 40, and the moisture can be discharged from the microwave cavity 40 through this air flow.

[0116] If the die has a channel for discharging moisture, to which the gap can lead, moisture will not flow out of the die 20 from various places and flow into the microwave cavity 40 as shown in the figure, but will be collected in the moisture discharging channel. Accordingly, moisture can be directly discharged from the die 20 to the outside of the microwave cavity 40. Such a design will be described below.

[0117] In this example, the fixing device of the microwave-transparent die 20 is designed to be integral with the cover plate 41. However, it is also conceivable that the device 200 is designed to be composed of two parts, that is, two halves and, if necessary, a separate bottom plate. In this case, the die 20 can be fixed and pressed together by corresponding elements on each half of the device 200. Figure 3 A corresponding design is shown.

[0118] Figure 3 200. The die 20 is arranged inside the device 200. In this example, the die 20 is designed to consist of three parts. The first half 20A of the die is shown, which is connected to the second half 20B of the die (see FIG. 20B ) at the die interface T. Figure 4 In the lower region of the die 20 a base part 24 is arranged which has a die interface with the two die halves 20A and 20B of the die 20 .

[0119] and Figure 1 Similarly, the device 200 has a microwave cavity 40 closed by a cover plate 41. The upper end of the die 20 passes through the cover plate 41. The bottom plate 24 of the die 20 also forms the downward end of the microwave cavity 40. The bottom plate part 24 incorporates a microwave-proof tube 25. Figure 3 The mold interface on the die half 20A is shown, which has a moisture drainage channel 22 arranged therein, which opens into a gap 21 (see FIG. 2 ) which is not shown in detail here. Figure 4 ).

[0120] A plurality of openings 23 open into the moisture discharge channel 22, and the moisture accumulated in the channel 22 can be discharged through these openings 23. As an alternative, pressure can also be applied to the channel 22 through these openings 23.

[0121] In the region of the mold interface between the bottom plate 24 and the die halves 20A, 20B, openings 23 can also be seen in the bottom plate 24. These openings 23 also open into moisture drainage channels 22, which are arranged in the bottom plate 24 in the region of the mold interface between the bottom plate 24 and the die halves 20A, 20B. The channels 22 are arranged circumferentially in the bottom plate part 24. In the die half 20A, the channels 22 are also formed continuously along the entire mold interface and open into the corresponding gaps.

[0122] It is also possible to drain moisture and / or to apply pressure to the channel 22 via the openings 23 in the bottom plate 24 .

[0123] Figure 4 Shows Figure 3 A detail of the cross-section of the die 20 is shown. The cross-section is parallel to the die interface between the base plate 24 and the die halves 20A, 20B (see Figure 3 ) extends. Shown and described in the figure are two die halves 20A and 20B, which are in contact with each other along the die interface T. It can be seen that the two die halves 20A and 20B form a mold cavity for filling the corresponding blank. It can be seen that a gap 21 is formed on the mold interface in the mold cavity area, which leads to a moisture discharge channel 22 toward the interior direction of the die 20, that is, toward the wall layer of the die 20. Both the gap 21 and the channel 22 are formed in half in the die halves 20A and 20B. In other words, the interior of the die, that is, the die cavity, is connected to the channel 22 in the radially outward direction through the gap 21. In the closed state, the die halves 20A and 20B are closely attached to each other behind the channel 22 in the same direction.

[0124] Figure 5 , 6 7 and 8 show perspective views of an alternative die 20, respectively. All dies 20 have die halves 20A and 20B (not shown) and a bottom plate 24. In all embodiments, the bottom plate 24 leads to a microwave-proof tube 25. The design of the bottom plate 24 is similar to that of the conventional die 20. Figure 3 The design of the bottom plate 24 described in is exactly the same. Figure 5 In the embodiment shown, the moisture drainage channel 22 in the die half 20A has no other openings. Figure 6 In the embodiment shown, the moisture discharge channel 22 has openings 23 in the upper region. These openings correspond to Figure 3 The opening 23 described in FIG. Figure 6 The embodiment shown corresponds to Figure 3 As for the moisture discharge channel 22, Figure 7 The embodiment shown corresponds to Figure 5The embodiment shown. That is, no other openings are designed in the channel 22. The difference is that additional gaps 21 are designed in the upper area of ​​the die 20 (in this case, the neck area), which directly lead into the die cavity of the die 20. However, these gaps 21 are arranged in an area of ​​the die, which corresponds to the area separated from the blank after the water content is reduced. Obviously, Figure 7 The embodiment shown can also be used with Figure 6 The exemplary embodiments shown can be combined with one another.

[0125] Figure 8 Other typical fibrous containers that can be produced using the methods described herein are shown by way of example. For example, container 100 can be seen, which is similar to Figure 1 and 2 The container 100 described is consistent. The container 100 is also bottle-shaped and additionally has a thread at the neck. The container 100 'is in the form of a bowl, while the container 100" is in the form of a cup.

[0126] Fig. 9 A typical bottle cap 300 that may be produced using the methods described herein is shown schematically.

Claims

1. A pressing die (20) for filling a fibrous blank, in particular for filling a container (100, 100', 100") or a fibrous closing element (300) of the container (100), for use in a microwave cavity (40), wherein: The pressing die (20) is capable of being penetrated by microwaves and is characterized in that, when the pressing die (20) is in a closed state, at least one gap (21) is formed on the pressing die (20) and moisture can escape through the gap (21).

2. The die (20) according to claim 1, characterized in that The at least one gap (21) is formed in a specific area of ​​the die (20), which corresponds to an area on the fibrous blank that is removed before using a product made from the fibrous blank.

3. The die (20) according to claim 2, characterized in that The at least one gap (21) is formed in a region of the die (20) corresponding to a neck of the blank.

4. The pressing die (20) according to any one of claims 1 to 3, characterized in that The die is composed of multiple parts and has one or more die interface (T) respectively, wherein the at least one gap (21) or the additional gap (21) is formed on at least one of the die interface (T).

5. The die according to claim 4, characterized in that The at least one gap (21) is formed in the circumferential direction along the entire mold interface (21).

6. The pressing die (20) according to any one of claims 1 to 5, characterized in that The at least one gap (21) leads to a moisture discharge channel (22) which is arranged in the wall layer of the die (20).

7. The pressing die (20) according to any one of claims 1 to 6, characterized in that The width of the at least one gap (21) is between 0.04 mm and 0.1 mm.

8. The pressing die (20) according to any one of claims 1 to 7, characterized in that Additional openings are added to the die 20 for draining moisture.

9. The pressing die (20) according to any one of claims 6 to 8, characterized in that The moisture discharge channel (22) is connected to a device for generating negative pressure or overpressure, so that a specific flow can be formed in the moisture discharge channel (22).

10. The pressing die (20) according to any one of claims 1 to 9, characterized in that The compression mold has a substantially uniform wall thickness.

11. The pressing die (20) according to any one of claims 1 to 10, characterized in that A supporting element is provided on the pressing die (20) so as to support the pressing die (20).

12. A method for reducing the moisture content in a fibrous blank, in particular a container (100, 100', 100") or a fibrous closing element (300) of said container (100), comprising the following steps - providing a wet fibrous blank in a pressing die, in particular a pressing die according to any one of claims 1 to 11; - placing an expandable tool (30) into the wet fibrous blank; - expanding said expandable tool (30), It is characterized in that The squeezed water is discharged through at least one gap (20) on the die by expansion.

13. The method according to claim 12, characterized in that After being placed in the compression mold (20), microwaves are applied to the wet fibrous blank.

14. The method according to claim 13, characterized in that The remaining moisture in the blank is converted into a gas phase by microwaves and discharged through the at least one gap (20).

15. The method according to any one of claims 12 to 14, characterized in that Remove moisture through strong exhaust ventilation.

16. The method according to claim 15, characterized in that For this purpose, at least one moisture discharge channel (22) opening into the gap is provided in the pressure die, wherein a flow is established in the moisture discharge channel (22) by means of negative pressure or positive pressure.

17. The method according to any one of claims 12 to 16, characterized in that After the water content is reduced, the portion of the blank introduced into at least one gap (21) of the die (20) will be separated from the blank.

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