Method and apparatus for the production of products from fibrous materials

Abstract

In a process for producing products (5) from fibrous materials, a fibrous material web (3) is formed in a first step from a fibrous raw material and water. The fibrous material web (3) or an intermediate product produced therefrom is formed in its moist state immediately after its formation in a forming device (4) into the fibrous product (5).

Description

[0001] The invention relates to a method for producing products from fibrous materials, wherein, in a first step, a fibrous material web is formed from a fibrous raw material and water. It also relates to an apparatus for producing products from fibrous materials, comprising a device for forming a fibrous material web from a fibrous raw material and water. Furthermore, the invention relates to a forming device for forming fibrous material webs or the intermediate products produced therefrom, comprising an upper tool and a lower tool.

[0002] Recently, there have been increasing efforts to replace components and products previously made of plastic materials with those made of natural fibers. These often involve products based on plant fibers, such as wood fibers.

[0003] Some of these components or products are manufactured using fiber casting, a primary molding process. The fiber is drawn from a suspension onto a screen mold and then pressed and dried.

[0004] This fiber casting process is inherently very slow, meaning only a small number of components can be produced in a given time. Therefore, for most components, this process is not competitive with plastic injection molding or similar processes. Furthermore, the tools used for fiber casting require very complex and expensive manufacturing, so fiber casting is only economically viable for large quantities.

[0005] Furthermore, processes for forming fibrous materials, for example, by compression molding, hydroforming, or drawing, are known from the general state of the art. These processes use paper or cardboard in a dry or slightly moistened state as the starting material.

[0006] The disadvantages of these forming processes are the limited degree of forming due to the bond-intensive nature of paper, as well as the comparatively severe formation of wrinkles, which arise due to the paper's lack of flowability due to the existing hydrogen bonds. These wrinkles lead to capillaries and leaks, which is why the molded parts produced using these forming processes have very limited use in packaging for products with a limited shelf life.

[0007] With regard to such processes and devices for converting paper and cardboard, reference is made, for example, to DE 195 09 863 A1 or DE 40 40 925 A1.

[0008] DE 101 56 590 A1 and DE 102 31 567 A1 disclose tools for the production of foam components. These sometimes have porous, vapor-permeable surfaces.

[0009] It is an object of the present invention to provide a method and a device for producing products from fibrous materials, with which products with almost any contour and a high degree of accuracy can be produced, wherein the method should be as simple as possible to carry out and the device should be as simple as possible to manufacture.

[0010] According to the invention, this object is achieved by the features mentioned in claim 1.

[0011] According to the invention, the fibrous material web or an intermediate product produced therefrom is formed in a forming device in its moist state immediately after its formation into a fibrous product. In contrast to known solutions for forming fibrous material webs, in which these are formed in a dry or slightly moistened state, according to the invention the forming takes place in the moist or initially wet state of the fibrous material web or the intermediate product produced therefrom immediately after its formation. In this moist state, the bonds resulting from hydrogen bonds between the individual fibers within the fibrous material web or the intermediate product produced therefrom areThe resulting intermediate product's friction is far less pronounced, and the fibers can therefore slide against each other much better than is the case with the prior art procedure, in which the fibrous material web is formed more or less in a dry state. This enables better flow of the fibrous material web or the intermediate product produced from it, and thus not only multidimensional stretching of the same, but also significantly higher degrees of deformation.

[0012] In contrast to known solutions, the forming process carried out in the inventive method allows the material of the fibrous material web or the intermediate product produced therefrom to flow, thus allowing for significantly better forming, which also requires less energy than known solutions. Furthermore, the significantly increased moisture content of the fibrous material web or the intermediate product produced therefrom also results in significantly lower friction between the material web or the intermediate product produced therefrom and the forming device, which further increases the deformability of the material web or the intermediate product produced therefrom and contributes to energy savings.

[0013] Compared to conventional forming processes, this enables a different type of shaping with significantly higher quality of the fiber-containing end product and a significantly higher process speed. Compared to fiber casting, up to ten times the process speed can be achieved.

[0014] A further advantage of the process according to the invention is that, compared to known solutions, less raw material is required to form the final product, yet the same strength can be achieved. Furthermore, the previously partially performed moistening of the fibrous material web can be omitted, leading to further cost savings.

[0015] Furthermore, the process according to the invention allows for significantly higher precision in the final product, allowing it to be used for applications whose requirements could previously only be met with plastic-based materials. In particular, the product manufactured using the process according to the invention is free of wrinkles, which was not possible with the known processes.

[0016] The statement “the fibrous material web or an intermediate product produced therefrom” refers to the fact that, although the fibrous material web is usually formed directly with the method according to the invention, it can be advantageous for certain reasons to produce an intermediate product from the fibrous material web and to form this intermediate product. Such an intermediate product can be a preform which is separated from the material web which is in a moist or initially wet state and is therefore itself in a moist or initially wet state. This separation of the material web, which can be carried out, for example, by punching and is carried out immediately after the web has been formed, can be particularly advantageous in the case of molded parts orThis can be useful for fibrous products with a high degree of deformation, in order to reduce tensile stresses and prevent cracks resulting from these tensile stresses, which can potentially occur when the entire material web is formed or handled in its web-like state. It is also possible, especially if the fibrous product to be manufactured has a large number of cavities, to make stress-relieving incisions in the material web in order to reduce the tensile stress on the material web.

[0017] In a very advantageous development of the invention, the dry content of the fibrous material web or the intermediate product produced therefrom during its forming can be 15 to 65%, preferably 20 to 60%. Such a dry content of the fibrous material web or the intermediate product produced therefrom, which is significantly lower than in known solutions, has proven to be a very good compromise with regard to good formability of the material web or the intermediate product produced therefrom, on the one hand, and sufficient strength of the same, on the other.

[0018] Furthermore, it can be provided that the fibrous material web or the intermediate product produced therefrom is heated and / or dewatered before forming. By heating the fibrous material web or the intermediate product produced therefrom before forming, its energy level is increased, i.e. the temperature of the water contained in the fibrous material web or the intermediate product produced therefrom is increased, whereby a more rapid evaporation of the water contained in the material web or in the intermediate product and thus a more rapid drying of the fibrous material web or the intermediate product produced therefrom can be achieved in the subsequent steps. This heating can be carried out, for example, using a suitable radiation dryer, i.e. a contactless heating device.Alternatively, or simultaneously with heating, dewatering of the material web or the intermediate product produced from it prior to forming is also possible. This allows the desired degree of dryness of the material web or intermediate product to be adjusted for forming. This involves basic dewatering of the fibrous material web or the intermediate product produced from it, which can save energy during subsequent drying.

[0019] In order to reduce the time required for the process according to the invention, it can further be provided that the fiber-containing product is dried after forming. Such final drying of the fiber-containing product, which can be carried out, for example, using microwaves as an alternative to the generally known drying methods, can be useful if, for example, for time or cost reasons, complete drying cannot or should not be carried out during forming.

[0020] A higher strength of the fibrous end product produced using the process according to the invention results when a portion of the fibrous raw material contains fibers with a length of more than 3 mm. Furthermore, higher degrees of deformation can be achieved, whereby the maximum fiber length is limited by the processability of the fibrous material web or the intermediate product produced therefrom. The maximum fiber length is preferably 20 mm.

[0021] Furthermore, it can be provided that the basis weight of the fiber-containing end product does not exceed 300 g / m 2Such a comparatively low basis weight not only enables easier forming of the fibrous material web or the intermediate product produced from it, but also saves raw materials, while achieving at least the same strength as known solutions with a higher basis weight. The basis weight of the fibrous final product is preferably at least 30 g / m 2 . In the forming process according to the invention, the ratio of the length of the fibrous material web or of the intermediate product produced therefrom to the basis weight of the same is maintained, which is not the case with known forming processes.

[0022] A further advantageous embodiment of the method according to the invention can consist in the fibrous material web moving continuously during the process, and in the forming device moving along with the movement of the fibrous material web. Although this requires adapting the movement of the forming device to the movement of the material web, no additional precautions regarding the movement of the material web are otherwise required.

[0023] Alternatively, it is also possible for the fibrous material web to be fed into a web storage device after its formation, with the forming device remaining essentially stationary during the forming of the fibrous material web, and with the fibrous material web being fed from the web storage device into the forming device during the forming process. Although this requires the creation of a web storage device or a similar device, no major intervention in the design of the forming device is necessary, as it remains stationary.

[0024] Particularly for the production of corrugated cardboard and similar products, it can be advantageous if the forming device is designed as a rotating pair of rollers into which the fibrous material web is continuously fed. This enables a further reduction in process time.

[0025] A further advantageous embodiment of the invention can consist in heating the fibrous material web or the intermediate product produced therefrom during forming by means of the forming device. By heating the fibrous material web or the intermediate product produced therefrom by means of the forming device, the glass transition temperature of the web can be exceeded, which leads to improved formability. In particular, higher degrees of forming can be achieved with less force. For this purpose, the forming device can be heated to temperatures of 200–400°C.

[0026] Claim 11 specifies an apparatus for producing products from fibrous materials.

[0027] By means of this device, which has a device for forming the fibrous material web from a fibrous raw material and water and a forming device immediately downstream of this device for forming the fibrous material web or an intermediate product made therefrom immediately after the formation thereof in its moist state into a fibrous end product, the method according to the invention can be carried out particularly easily.

[0028] By arranging the forming device directly after the device for forming the fibrous material web, the forming of the material web or the intermediate product produced therefrom can be carried out in a moist or wet state, which, as already mentioned above, enables significantly higher degrees of forming. The device according to the invention can have a comparatively simple structure and, in particular, can be integrated into existing devices.

[0029] In a very advantageous development of the device, the forming device can be heated. Heating the forming device heats the fibrous material web or the intermediate product produced from it during its forming process, thereby enabling even higher degrees of forming while simultaneously achieving a certain degree of drying.

[0030] In order to dissipate any water vapor that may be generated during the heating of the fibrous material web or the intermediate product produced therefrom during its forming, the forming device can furthermore be provided with a vapor-permeable structure for supplying and / or discharging water vapor to and / or from the material web to be formed or the intermediate product produced therefrom. Furthermore, this allows, if necessary, the supply of water vapor to the material web to be formed or to the intermediate product produced therefrom, thereby reducing the dry content of the same, if necessary, and setting the desired conditions for forming the material web or the intermediate product produced therefrom.The radiant energy of the heated surfaces of the forming device creates water vapor in the form of vapor cushions within the fibrous material web or the intermediate product produced from it, preventing direct contact between the forming device and the fibrous material web or the intermediate product produced from it. This also helps avoid tribological problems during the forming of the fibrous material web or the intermediate product produced from it into the multidimensional, fibrous product.

[0031] A forming device for forming fibrous material webs or intermediate products made therefrom is specified in claim 14.

[0032] This comprises an upper tool and a lower tool, at least one of which is heated. By heating the upper and / or lower tool, the temperature of the fibrous material web or the intermediate product produced from it can be increased, thus achieving the desired degree of forming. Compared to conventional solutions, the components of the forming device are significantly simpler and therefore more cost-effective.

[0033] In an advantageous development of the forming device, a vapor-permeable structure can be provided for supplying and / or removing water vapor to and / or from the fibrous material web to be formed or the intermediate product produced therefrom, in order to remove any water vapor that may be generated during heating of the material web or the intermediate product produced therefrom during its forming. Furthermore, this allows the supply of water vapor to the material web to be formed or to the intermediate product produced therefrom, thereby potentially reducing the dry content of the same and establishing the desired conditions for forming the material web or the intermediate product produced therefrom.

[0034] In the following, embodiments of the invention are shown in principle with reference to the drawing.

[0035] It shows: Fig. 1 a very schematic structure of an apparatus for carrying out the method according to the invention; Fig. 2 a first step in carrying out the method according to the invention; Fig. 3 a second step in carrying out the method according to the invention; Fig. 4 a third step in carrying out the method according to the invention; Fig. 5 a section through a forming device according to the invention; Fig. 6 a perspective view of a part of the forming device from Fig. 5; Fig. 7 shows a further embodiment of the device according to the invention; Fig. 8 an alternative to the embodiment of Fig. 7; Fig. 9 another alternative to the embodiment of Fig. 7; Fig. 10 another alternative to the embodiment of Fig. 7; Fig. 11 an example of a device provided with one of the devices according to Fig. 7 to 10 manufactured fibrous end product; Fig. 12 a first variant of the fibrous end product from Fig. 11; Fig. 13 a second variant of the fibrous end product from Fig. 11; Fig. 14 a third variant of the fibrous end product from Fig. 11; Fig. 15 a fourth variant of the fibrous end product from Fig. 11; and Fig. 16 a fifth variant of the fibrous end product from Fig. 11.

[0036] Fig. 1 shows a very schematic illustration of a device 1 for producing fibrous components or products. The device 1 comprises a device 2 for forming a fibrous material web 3 from a fibrous raw material (not shown) and water. Furthermore, the device 1 comprises a forming device 4, immediately downstream of the device 2 for forming the material web 3 in the process direction designated by "x", for forming the material web 3 or an intermediate product (not shown) produced from the material web 3 immediately after formation thereof in its moist state into a fibrous product 5. The fibrous product produced by the device 1 and the process carried out therewith can be designed, for example, as a cup or bowl, but also as a technical component.

[0037] The following describes only embodiments in which the fibrous material web 3 is formed. However, in almost all embodiments, it is also possible to first produce an intermediate product from the fibrous material web 3 and to form this in the same or at least a similar manner as described for the fibrous material web 3. Such an intermediate product can be a preform that is separated from the material web in a moist or initially wet state and is thus itself in a moist or initially wet state. For the sake of simplicity, the term "or an intermediate product produced therefrom" is omitted in each case.

[0038] The fibrous raw material preferably comprises natural fibers, such as cellulose and / or wood fibers. However, it is also possible to combine different fibers and, if necessary, to use synthetic or semi-synthetic fibers, such as viscose. The device 2 for forming the fibrous material web 3 is designed similarly to a wet-laid nonwoven system or a headbox of a paper or board machine and has a screen (not shown) onto which the suspension of the fibrous raw material and the water is applied. The screen is, in particular, an inclined screen, which enables the formation of a fibrous material web 3 with essentially isotropic properties.

[0039] If anisotropic material properties of the fibrous material web 3 are to be achieved, this can be achieved by varying the speed of the screen and the fabric application of the wet-laid nonwoven machine. Such anisotropic material properties of the fibrous material web 3 may be desired, for example, if certain properties of the fibrous product 5, such as its tensile strength, are desired only in one direction.

[0040] Since the basic functioning of a headbox, which as mentioned can be compared with the device 2 for forming the fibrous material web 3, is known per se, it will not be discussed in more detail here.

[0041] Because the forming device 4 is arranged directly downstream of the device 2 for forming the fibrous material web 3, the fibrous material web 3 enters the forming device 4 in its moist or initially wet state and can therefore be formed much better than in known solutions in which a paper or cardboard web produced at another location and wound onto a roll is formed in its dry or possibly slightly moistened state in a separate forming device.

[0042] The dry matter content of the fibrous material web 3 during its forming process can be 15 to 65%, preferably 20 to 60%. In other words, the moisture content of the fibrous material web 3 during its forming process is 35 to 85%, preferably 40 to 80%. This moisture content is thus significantly higher than in known solutions.

[0043] Part or all of the fibrous raw material may contain fibers with a length of more than 3 mm and less than 20 mm.

[0044] In the present case, a device 6 is located between the device 2 for forming the fibrous material web 3 and the forming device 5, with which the fibrous material web 3 can be heated and / or dewatered before forming. The device 6 can, for example, be a blower or similar device with which heat is introduced into the fibrous material web 3. In principle, the device 6 can also have one or more press rollers. The device 6 serves not only to introduce heat and thus energy into the fibrous material web 3, but also to be able to adjust the above-mentioned dry content of the same. If necessary, the device 6 for heating and / or dewatering the fibrous material web 3 before forming can also be dispensed with.

[0045] Further, a drying device 7 is arranged downstream of the forming device 4, with which the fibrous product 5 formed in the forming device 4 can be dried. Further devices (not shown) for laminating, embossing, and / or punching the fibrous product 5 can be connected to the drying device 7 or the forming device 4. Depending on the dry content of the fibrous material web 3, the drying already performed in the preceding steps, in particular during the forming itself, and the requirements of the fibrous product 5, the drying device 7 can also be omitted.

[0046] The basis weight of the fibrous product 5 is preferably not more than 300 g / m 2 and preferably at least 30 g / m 2 .

[0047] In the Fig. Figures 2 to 5 illustrate several steps in the forming of the fibrous material web 3 by means of the forming device 4. First, it can be seen that the forming device 4 comprises an upper tool 4a and a lower tool 4b. In the present case, the lower tool 4b is rigid and the upper tool 4a is movable according to the arrow "z". By inserting the upper tool 4a into the lower tool 4b, as shown in Fig. 3, the fibrous material web 3 formed in the device 2 is transformed into the fibrous product 5.

[0048] In a manner not shown, the forming device 4 can have several stages in which the fibrous material web 3 is formed into the fibrous product 5 in several forming steps.

[0049] In the present case, the forming device 4 is heated in a manner not shown. This can be achieved by heating the upper tool 4a and / or the lower tool 4b, for example, by means of electrical current, so that the surfaces thereof facing the fibrous material web 3 are brought to a desired temperature. By heating the forming device 4 in this way, the fibrous material web 3 can be heated and at least partially dried during the forming process. If necessary, the drying device 7 arranged downstream of the forming device 4 can be dispensed with by a corresponding design of the heating device (not shown) of the forming device 4.

[0050] The Fig. 5 and Fig. 6 show further details of the forming device 4. It can be seen that the forming device 4, in this case both the upper tool 4a and the lower tool 4b, has a vapor-permeable structure for supplying and / or removing water vapor to and / or from the material web 3 to be formed. In this case, the vapor-permeable structure is formed by a plurality of bores in the upper tool 4a and the lower tool 4b. However, it is also possible to manufacture the entire upper tool 4a and / or the entire lower tool 4b from a sintered material, which forms the vapor-permeable structure. The manufacture of the upper tool 4a and / or the lower tool 4b using a 3D printing process to form the vapor-permeable structure is also conceivable.This design of the forming device 4 allows, among other things, the water vapor that is generated by heating the material web 3 to be formed by means of the radiant energy of the heated surfaces of the upper tool 4a and the lower tool 4b to be removed.

[0051] To control or regulate the supply and discharge of steam to and from the forming device 4, a control or regulating device (not shown) can be provided, with which the steam pressure, the temperature, as well as the closing speed and the closing pressure of the forming device 4 can be controlled or regulated. For this purpose, the control or regulating device can have one or more valves that open or close the bores in the upper tool 4a and the lower tool 4b or generally open or close access to the steam-permeable structure.

[0052] During the forming of the fibrous material web 3, it can be provided that it moves continuously in the direction designated "x" during the process, and that the forming device 4 moves along with the movement of the material web 3. The movement back to the starting point of the forming device 4 can occur at a higher speed. This movement of the forming device 4 can be controlled by a control device, by means of which the accelerations and decelerations can be carried out harmoniously.

[0053] Alternatively, however, it is also possible to guide the material web 3 into a web storage device (not shown) after its formation in the device 2. This allows the forming device 4 to remain stationary during the forming of the material web 3, and the material web 3 can be fed to the forming device 4 from this web storage device during the forming process.

[0054] If, as indicated above, the intermediate product produced from the fibrous material web 3 is formed instead of the fibrous material web 3, this intermediate product can be formed discontinuously after being separated from the material web 3.

[0055] In the Fig. 7 to 10 show several embodiments of the forming device 4, in which the device is designed as a rotating roller pair comprising two rollers 4c and 4d, into which the material web 3 is continuously fed. In all embodiments according to the Fig. 7 to 10, the rollers 4c and 4d of the roller pair forming the forming device 4 are each provided with a plurality of elevations 8, which serve to form the fibrous material web 3. The difference between the individual embodiments of the Fig. 7 to 10 consists in the arrangement of the essentially hemispherical elevations 8 on the two rollers 4c and 4d, which in this case are essentially hemispherical, which results in different fiber-containing products 5, particularly with regard to their flexural rigidity. For the supply and / or removal of steam, the rollers 4c and / or 4d can have suitable rotary passages on their respective shaft ends.

[0056] In the case of the fibrous product 5, which is made with the Fig. The corrugated cardboard produced by the forming device 4 shown in Figures 7 to 10 is a type of corrugated cardboard which, unlike conventional corrugated cardboard, does not have a preferred folding direction. Rather, the corrugated cardboard is isotropic and thus, in principle, torsionally rigid in every direction, resulting in a significantly higher bending strength. The torsionally rigidity of the cardboard produced by the forming device 4 according to Figure 1 is Fig. 7 to 10 also depends in particular on the arrangement, size and mutual spacing of the elevations 8 on the two rollers 4c and 4d.

[0057] In the Fig. 11 to 16 are various embodiments of the forming device 4 according to the Fig. 7 to 10 manufacturable fiber-containing product 5.

[0058] Here, the Fig. 11, Fig. 12 and Fig. 13, the fiber-containing products 5 are each formed only on one side. Fig. The embodiment of the fibrous product 5 shown in Figure 12 is additionally covered on one side. Fig. The embodiment of the fiber-containing product 5 shown in Figure 13 is covered on both sides.

[0059] The Fig. 14, Fig. 15 and Fig. The embodiments of the fibrous product 5 shown in Figure 16 are each formed on two sides. Fig. 15 is additionally covered on one side and the Fig. The embodiment shown in 16 is covered on both sides.

[0060] In addition, it would be possible to use a foaming agent to increase the stiffness of the fiber-containing product 5 and / or to achieve a certain damping effect with it so that it can be used as a cushioning material or the like. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 195 09 863 A1

[0007] DE 40 40 925 A1

[0007] DE 101 56 590 A1

[0008] DE 102 31 567 A1

[0008]

Claims

[1] Method for producing products (5) from fibrous materials, wherein in a first step a fibrous material web (3) is formed from a fibrous raw material and water, characterized by that the fibrous material web (3) or an intermediate product made therefrom is formed into the fibrous product (5) in a forming device (4) immediately after its formation in its moist state. [2] Method according to claim 1, characterized by that the dry content of the fibrous material web (3) or of the intermediate product produced therefrom during its forming is 15 to 65%, preferably 20 to 60%. [3] Method according to claim 1 or 2, characterized by that the fibrous material web (3) or the intermediate product produced therefrom is heated and / or dewatered before forming. [4] Method according to one of claims 1 to 3, characterized bythat the fiber-containing product (5) is dried after forming. [5] Method according to one of claims 1 to 4, characterized by that part of the fibrous raw material contains fibres with a length of more than 3 mm. [6] Method according to one of claims 1 to 5, characterized by that the basis weight of the fibrous product (5) does not exceed 300 g / m 2 amounts. [7] Method according to one of claims 1 to 6, characterized by that the fibrous material web (3) moves continuously during the process, and that the forming device (4) moves along with the movement of the fibrous material web (3). [8] Method according to one of claims 1 to 6, characterized bythat the fibrous material web (3) is guided into a web storage device after its formation, wherein the forming device (4) remains substantially stationary during the forming of the fibrous material web (3), and wherein the fibrous material web (3) is fed from the web storage device into the forming device (4) during the forming. [9] Method according to one of claims 1 to 6, characterized by that the forming device (4) is designed as a rotating pair of rollers (4c, 4d) into which the fibrous material web (3) is continuously fed. [10] Method according to one of claims 1 to 9, characterized by that the fibrous material web (3) or the intermediate product produced therefrom is heated during the forming process by means of the forming device (4). [11] Device (1) for producing products (5) from fibrous materials, comprising a device (2) for forming a fibrous material web (3) from a fibrous raw material and water, characterized by a forming device (4) immediately downstream of the device (2) for forming the fibrous material web (3) for forming the fibrous material web (3) or an intermediate product produced therefrom immediately after the formation of the same in its moist state into a fibrous product (5). [12] Device according to claim 11, characterized by that the forming device (4) is heated. [13] Device according to claim 11 or 12, characterized by that the forming device (4) has a vapor-permeable structure for supplying and / or removing water vapor to and / or from the fibrous material web (3) to be formed or the intermediate product produced therefrom. [14] Forming device (4) for forming fibrous material webs (3) or intermediate products made therefrom, with an upper tool (4a) and a lower tool (4b), characterized by that the upper tool (4a) and / or the lower tool (4b) is heated. [15] Forming device (4) according to claim 14, characterized by a vapor-permeable structure for supplying and / or removing water vapor to and / or from the fibrous material web (3) to be formed or the intermediate product produced therefrom.

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