Three-dimensional moulded body, device and method for producing a three-dimensional moulded body

Abstract

The invention relates to a method for producing a preform for producing three-dimensional moulded bodies, a method for producing a three-dimensional moulded body (1) and a device for producing a three-dimensional moulded body (1). The invention also relates to a three-dimensional moulded body (1), consisting of filling material (5), wherein the filling material (5) is injected into an at least two-part preform and is connected by means of pressing and / or the application of heat and / or binder. A preform part (2) is thus formed. Essential to the invention is that the preform part (2) offers higher flexibility for a subsequent deformation. In an at least two-part end mould with an end press lower mould (8) and an end press upper mould (7), the preform part (2) is pressed and thus forms the three-dimensional moulded body (1).

Description

[0001] Three-dimensional molded body, device and method for producing a three-dimensional molded body

[0002] Description

[0003] The invention relates to a three-dimensional shaped body according to the preamble of claim 10, a method for producing a three-dimensional shaped body according to the preamble of claim 1 and a device for producing a three-dimensional shaped body according to the preamble of claim 6.

[0004] Known three-dimensional molded bodies are made from filler material that is blown into a multi-part mold by an air stream. The filler material adheres to the inner wall of the mold and is bonded together by compression and / or heat application and / or a binding agent. Such molded bodies have the advantage that individual three-dimensional shapes can be produced that are both lightweight and stable. Three-dimensional molded bodies are used, for example, for soundproofing, thermal insulation, or in the automotive industry. The molded bodies can be used to line vehicle interiors or as supports. Typically, single-piece parts with the largest possible surface area are used. Fiber material, material flakes, or binding fibers are used as filler materials. Resin and / or starch are used as binding materials.

[0005] Such molded bodies are known as fiber molded parts from the prior art, for example, DE 103 24 735 and DE 10 2012 019 534. To avoid repetition, reference is explicitly made to the content of these documents, particularly with regard to the manufacturing process.

[0006] Alternatively, airlaid processes are known from the prior art for the production of nonwovens. In these processes, the fibers are compressed into nonwovens by rollers. A disadvantage of the previously known molded bodies from the prior art is that they must have a minimum wall thickness due to production requirements, which prevents the formation of thin-walled molded bodies, especially with high material density. This is due, on the one hand, to the material properties of the filling material and, on the other hand, to the difficult handling of particularly thin-walled molded bodies during the manufacturing process.

[0007] The present invention is therefore based on the object of proposing a manufacturing method for preforms for producing a three-dimensional molded body and for the three-dimensional molded body, which three-dimensional molded body is characterized by a thin wall thickness.

[0008] It is a further object of the invention to propose such a three-dimensional shaped body and a device for producing such a three-dimensional shaped body.

[0009] This object is achieved by a method for producing a preform for the production of a three-dimensional molded body according to claim 1 and a device for producing a three-dimensional molded body according to claim 6 as well as by a three-dimensional molded body according to claim 10. Preferred embodiments of the method according to the invention can be found in claims 2 to 5.

[0010] Preferred embodiments of the invention according to the device can be found in claims 7 to 9. The wording of all claims is hereby explicitly incorporated into the description by reference.

[0011] The method according to the invention for producing a preform for the production of a three-dimensional shaped body comprises the following process steps:

[0012] A Production of a preform with a shape that is structured at least in some areas and offers increased flexibility for subsequent deformation, with at least the following process steps:

[0013] A.1 Providing an at least two-part preform comprising an upper mold and a lower mold, wherein the upper mold and / or the lower mold have on an inner side at least in some areas a negative of the structured shape of the preform part to be achieved,

[0014] A.2 Blowing in filling material by means of an air flow into the at least two-part preform, wherein the air escapes through openings in the at least two-part preform, so that the blown-in filling material accumulates on the inner sides of the at least two-part preform or inserting a fleece of filling material;

[0015] A.3 Combining and structuring the filling material to form a preform by pressing and / or applying heat and / or by means of a binder;

[0016] A.4 Opening the at least two-part preform and removing the three-dimensional preform part;

[0017] It is essential that in a process step A the upper mold and / or the lower mold have on an inner side, at least in some areas, a negative of the structured shape of the preform to be achieved.

[0018] This results in the advantage according to the invention that the partially structured shaping of the preform enables increased flexibility of the preform for subsequent deformations.

[0019] Within the scope of the invention, the structured shape can be considered a surface profile with which the preformed part is to be provided in certain regions or is provided after its production. In particular, the surface profile can comprise a plurality of profile elements that are to be or are formed at least in certain regions in a regular arrangement on the preformed part. In particular, the profile elements can each be elongated, i.e., with a main extension axis.

[0020] The surface profile can be designed to influence a mechanical property, in particular a dimensional stiffness, of the preform compared to an unstructured, in particular unprofiled, component region of the preform. In particular, an anisotropic dimensional stiffness can be set in this way, wherein the dimensional stiffness is higher around and / or along a first axis than around and / or along a second axis. An advantage that can be achieved in this way can be that the preform has increased flexibility in certain regions and can be removed from the preform with little effort by deforming this region. At the same time, the preform can have increased stiffness in certain regions, so that this region is not deformed or is only slightly deformed during the said removal of the preform from the preform.This improves the handling of the preform, which particularly facilitates handling by means of an automated handling device.

[0021] The preform preferably has a substantially rotationally symmetrical shape. A circumferential wall is connected to a base and has an opening on a side opposite the base. The wall is preferably inclined with respect to a rotation axis, such that the preform is conical. Furthermore, the wall has the structured shape, wherein the above-mentioned profile elements are elongated and run between the base and the opening. The profile elements furthermore each have a height profile along their respective longitudinal axis, wherein the height of the profile elements is lower in the region of the base than in the region of the opening. The profile elements can be formed on an inner side and / or an outer side of the wall. Accordingly, the preform is formed, at least in regions, as a negative of the shape of the preform part described above.In particular, the profile elements can each have a pointed edge and / or a rounded cross-section, for example in the form of a triangle, a curve or a wave section.

[0022] To produce the three-dimensional molded part, further processing can then preferably be carried out using the following process steps:

[0023] B Providing the preform in an at least two-part final mold with a lower press mold and an upper press mold, wherein the inner contour of the at least two-part final mold corresponds at least partially to the outer contour of the three-dimensional molded body to be achieved, C Pressing the preform to form the three-dimensional molded body, wherein the preform following the structured shaping forms the three-dimensional molded body;

[0024] D Opening the final mold, which consists of at least two parts, and removing the three-dimensional molded body.

[0025] In an advantageous embodiment of the process, the filling material injected in process step A.2 achieves a compression ratio of greater than 1.5 and less than 2.5 before bonding and structuring in process step A.3. The compression ratio describes the ratio of the injection density of the filling material to the loose bulk density of the filling material.

[0026] The advantage resulting from this degree of compression is that, in contrast to loose filling, the filling material remains in the desired position and thus the contour is maintained.

[0027] In an advantageous embodiment of the process, the filling material of the three-dimensional molded body is compressed in process step C by pressing the molds of the at least two-part final mold with a contact force of 500 N to 70,000 N, preferably 2,000 N to 50,000 N. The level of the contact force depends in particular on the shape and size of the molded body. For smaller molded parts, such as yogurt cups, the contact force is preferably 1,500 N to 3,000 N; alternatively, for larger molded parts, the contact force is preferably 10,000 N to 70,000 N, preferably 40,000 N to 70,000 N.

[0028] By compressing the filler material of the three-dimensional molded body with the contact force, which leads to compaction, a dimensionally stable preform is formed. The compaction can take place locally or affect the entire fiber molded part. For this purpose, for example, an auxiliary mold can be attached which has a different inner contour and thus leads to a locally deviating density distribution. This method is described in DE 10 324 735 B3. The details of the method, in particular with regard to the creation of an inhomogeneous density distribution, are hereby incorporated by reference. In a preferred embodiment, fiber material and / or material flakes are blown in as filler material, preferably that binding fibers and / or binding material, preferably resin and / or starch, are blown in. Typically, the ratio of binding fiber / binding powder to the fibers regulates the strength of the component, as is known from the prior art.The ratio of binding fibers to fiber material has a significant influence on other properties such as dimensional stability.

[0029] In an advantageous embodiment of the method, the preform is heated in a method step C.1 before method step C to a temperature of 100 °C to 200 °C, in particular of 150 °C to 300 °C.

[0030] The advantage here is that heating the preform changes the material properties of the binding fibers of the filler material. This change activates the binding properties by reaching the melting point of the binding material. This melting point of the binding material is therefore crucial for the temperature window in process step C.1.

[0031] Preferably, in process step C, which comprises pressing the preform to form the three-dimensional molded body, the structured shape on the preform produced in process steps A1 to A4 is at least reduced, preferably completely eliminated. In particular, a substantially smooth, i.e., unprofiled surface is produced instead of the structured molded body. One advantage here is that the structured shape of the preform does not have to be embodied on the produced three-dimensional molded body. In this respect, for example, visible surfaces or functional surfaces of the molded part to be produced can be provided with the structured shape only during production of the preform in order to achieve the desired advantages for handling without impairing the appearance or function of the molded body to be produced.

[0032] In particular, the density of the preform is, at least in some areas, lower than the density of the three-dimensional molded part. The above-described object is further achieved by a device according to claim 6.

[0033] The device according to the invention comprises, as is known per se, at least one at least two-part preform comprising an upper mold and a lower mold, wherein the upper mold and / or the lower mold have, at least in some areas, a negative of a desired structured shape of the preform on an inner side. Furthermore, the device comprises at least one two-part final mold comprising a lower pressing mold and an upper pressing mold, wherein the inner contour of the at least two-part final mold corresponds, at least in some areas, to the outer contour of the desired three-dimensional molded body.

[0034] What is essential is that this device comprises a preform and a final mold. The preform is used to produce a preform part which has different properties than the three-dimensional molded body produced using the final mold. The preform part is characterized by its flexibility, which is achieved despite its dimensional stability. This flexibility is created by the shaping structure formed in certain regions on the upper mold and / or the lower mold. The structured shaping creates the flexibility by means of a shell surface allowance. This can be understood as a local excess of material in the preform part, which can be compacted and / or distributed during the pressing of the three-dimensional molded body in order to form a substantially flat surface of the three-dimensional molded body. The shell surface allowance therefore makes it possible to form the three-dimensional molded body using the final mold.The advantage is that thin-walled three-dimensional molded bodies can be formed which have a high or low material density in some areas.

[0035] The method according to the invention is preferably designed for implementation by means of the device according to the invention and / or a preferred embodiment thereof. The device according to the invention is preferably designed for implementation of the method according to the invention and / or a preferred embodiment thereof. In an advantageous embodiment of the device according to the invention, the negative of the structured shape of the at least two-part preform (hereinafter also referred to as the structure of the two-part preform) is rippled, waved, or ribbed. Alternatively, the structure of the at least two-part preform can have regions with different structures.

[0036] The advantage here is that the flexibility and dimensional stability of the preform can be varied by designing the negative of the structured mold. The structure of the at least two-part preform also influences the release of the preform part from the preform.

[0037] An advantageous embodiment of the at least two-part preform has different interstitial volume sections. These different interstitial volume sections arise from a changing distance between the lower mold and a lower injection mold. The different interstitial volume sections allow for uneven filler material deposition during injection of the filler material. After injection, the upper injection mold is preferably removed and replaced with an upper mold.

[0038] An advantage of this design is that it allows for targeted material reinforcement of the preform in specific areas. This targeted reinforcement increases the stability of the three-dimensional molded body.

[0039] A further advantageous embodiment is directed to the at least two-part final shape, wherein the at least two-part final shape can be heated to a temperature deviating from the ambient temperature, preferably in the range from 100 °C to 200 °C, in particular from 150 °C to 300 °C.

[0040] An advantage of this embodiment is that the filling material of the preform can be heated, for example to melt the binding fibers in order to activate the binding property.

[0041] The above-described object is further achieved by a three-dimensional molded body according to claim 10. The three-dimensional molded body according to the invention is formed from a filler material. According to the invention, the three-dimensional molded body is produced using the above-described method and the above-described device.

[0042] It is essential that the three-dimensional molded body is created from a preform.

[0043] An advantageous embodiment of the three-dimensional shaped body comprises a shaped body which has regions of different wall thicknesses.

[0044] These areas, which differ in wall thickness, are advantageous because a targeted reinforcement of the molded body is achieved without providing the entire molded body with a thick wall thickness.

[0045] Other options for activating the fibers include heating the mold with contact heat using hot plates, introducing hot steam from a steam generator, or using microwaves. Additionally or alternatively, an adhesive can be introduced into the preform. This can be achieved, for example, by mixing the filler material with an adhesive powder or hot melt adhesive before blowing. After the mixture is blown in, the adhesive is thermally activated.

[0046] The three-dimensional shaped body according to the invention as well as the device according to the invention and the method according to the invention are basically suitable for applications in which three-dimensional shaped bodies are used or produced which are to have special properties, for example with regard to thin wall thicknesses and high material densities.

[0047] The fiber molded part according to the invention is therefore preferably designed for use in packaging technology. Achievable wall thicknesses range, for example, from 0.5 mm to 5 mm. Natural fibers (e.g., hemp, water hyacinth, miscanthus, grass), cellulose fibers or flakes, as well as purified recycled material, for example, in the form of leather waste fibers or shredded packaging material, can be used as filler material. These can have properties such as food safety, such as industrially produced cellulose fibers and flakes, or biologically tanned leather fibers.

[0048] Further advantageous features and embodiments of the method and device according to the invention are explained below with reference to exemplary embodiments and the figures. Herein:

[0049] Figure 1 with the partial images a to i shows the method steps of an embodiment of a method according to the invention.

[0050] Figure 2 with the partial images a to e shows a schematic sectional view of various embodiments of an upper mold for producing a preform for producing a three-dimensional molded body according to the invention;

[0051] Figure 3 with the partial images a and b are schematic representations of a preform produced by the method according to the invention and by the device according to the invention;

[0052] Figure 4 is a schematic sectional view of a three-dimensional shaped body produced by the method and device according to the invention;

[0053] Figure 5, with partial images a to d, shows a schematic sectional view of various exemplary embodiments of the structured shapes of the lower mold of the device according to the invention for producing a preform for producing a three-dimensional molded body according to the invention; Figure 1, with partial images a to i, shows the process steps of one embodiment of a process according to the invention.

[0054] To produce three-dimensional molded bodies, a preform is first produced, shown in Figures 1a to 1f. The preform has a structured shape, at least in some areas, which offers increased flexibility for subsequent deformation. The preform is pressed into a final shape to form the three-dimensional molded body, shown in Figures 1g to 1i.

[0055] The production of the preform comprises the following process steps, shown in Figures 1a to 1f:

[0056] In method step A.1, an at least two-part preform comprising an upper mold 3 and a lower mold 4 is provided, wherein the upper mold 3 and / or the lower mold 4, in this case the lower mold, have on an inner side at least in regions a negative of the structured shape of the preform part 2 to be achieved.

[0057] In this case, the lower mold is round and features a zigzag geometry in an outer area surrounding a free, round inner area. This zigzag geometry determines the subsequent structured shape of preform part 2.

[0058] In process step A.2, filling material 5 is blown into the at least two-part preform by an air flow, wherein the air escapes through openings in the at least two-part preform, so that the blown-in filling material 5 is deposited on the inner sides of the at least two-part preform.

[0059] The filling material used in this case is fibers made from hemp, leather waste fibers, cellulose, or viscose, or mixtures thereof. A thermoplastic binder, either in powder form with grain sizes ranging from 0.1 mm to 0.5 mm or binding fibers in lengths ranging from 3 mm to 51 mm, is added to the fibers.

[0060] The fiber material is deposited in the space between the inner surfaces of the upper and lower molds. Excess air is released from the preform through air vents, which are not shown for clarity.

[0061] In process step A.3, the filling material 5 is connected and structured to form a preform by pressing and / or applying heat and / or by a binder;

[0062] This enables the production of a preform with a structured wall, which offers greater flexibility for subsequent deformation during compression. The preform is formed circularly by the exemplary lower mold and, in this case, has a zigzag pattern in an outer area, similar to a muffin tin.

[0063] In the further course of the process, the preform 2 is pressed into a final shape to form the three-dimensional molded body, shown in the partial figures 1g to i:

[0064] In a process step B, the preform part 2 is transferred into a two-part final mold with a final press lower mold 8 and a final press upper mold 7, shown in Figure 1g.

[0065] The two-part final mold has an inner contour that corresponds to the outer contour of the desired three-dimensional molded body 1. In this case, the final press lower mold 8 is cup-shaped, and the final press upper mold 7 is fitted as a negative to the final press lower mold 8.

[0066] The preform part 2 adapts to the inner contour of the final mold in its final shape and folds the structured shape, in this case the zigzag geometry in the outer area, to the inner side of the final press mold 8. Due to the structured shape, in this case in the form of the zigzag geometry, the preform part has increased flexibility for the subsequent deformation.

[0067] In the following process step C, the preform 2 is pressed into the three-dimensional molded body 1, wherein the preform 2, following the structured shaping, forms the three-dimensional molded body 1, shown in Figure 1h. In a final process step D, the two-part final mold can be opened and the three-dimensional molded body 1 can be removed, shown in Figure 1g.

[0068] Figures 2a to 2e show different embodiments of schematic representations of an upper mold for producing a preform for producing a three-dimensional molded body according to the invention.

[0069] The design of the upper mold 3a is shown in a sectional view in Figures 2b and 2a. The design of the upper mold is shown schematically as a trapezoid. The trapezoidal shape determines the shape of the preform to be produced, since the trapezoidal contour is crucial for forming the intermediate space, which leads to targeted filler material deposition during the process step of blowing in the filler material. The exemplary embodiment shown includes air escape openings 3a.1. These openings are necessary because in process step A2 the filler material is blown in via an air stream, which introduces the filler material and must then escape. The openings 3a.1 are selected to be correspondingly small so that the filler material can accumulate within the intermediate space and is not carried out of the at least two-part preform with the air stream.

[0070] To avoid repetition, only the differences to Figures 2a and 2b will be discussed below with regard to Figures 2c to 2e.

[0071] Figure 2c shows a version of the upper mold 3b that features additional bevels. These steps lead to a change in the resulting interstitial volume.

[0072] Figure 2d shows a version of the upper mold 3c that has additional recesses. These recesses lead to a section-by-section change in the resulting interspace volume. Figure 2e shows a version of the upper mold 3d, which is schematically depicted as rectangular. This embodiment does not exhibit a positive contour for shaping.

[0073] Figure 3 shows a schematic representation of a preform part 2. The preform part 2 is made of filler material, in this case a fiber mixture of fibers, binding fibers, and binder. The preform part 2 has sections marked with the capital letter A. A structure is formed in these sections. In this example, the structure is zigzag-shaped. The structure causes the sections to develop increased flexibility. The zigzag-shaped structure runs in a ring shape in the lateral surface of the regions marked with A. Figure 3b shows a plan view showing the regions with the zigzag-shaped structure.

[0074] Figure 4 shows a schematic representation of a three-dimensional molded body 1 according to the invention. The molded body 1 is manufactured from the preform 2 in process step C. By attaching it to the outer contour and pressing it together, the structured shape "disappears," and a uniform surface of the three-dimensional molded part is created. The three-dimensional molded body 1 according to the invention also has a contour that differs from the preform 2. Due to the pressing, the wall thickness of the three-dimensional molded body 1 according to the invention is thinner than that of the preform 2, which can be seen in Figure 3, and the wall material density is higher.

[0075] Figures 5a to 5d show examples of the structure of the negative of the structured shape to be achieved of the preform part for the upper mold and / or lower mold of the two-part preform for producing a preform part. These structural shapes 9 shape the structure A, which is formed on the preform part 2 in Figure 3. These structural shapes are formed in regions on both the lower mold 4 and the upper press mold 6. The outer contour of the structural shape 9, which forms the actual structure, is decisive for the shape. Figure 5a shows a structural shape 9a; this structural shape 9a is characterized by the fact that the contour has a repeating geometry. What is important about this geometry is that it has a rising and a falling flank; these flanks are at right angles to one another.At the intersection points of the rising and falling flanks of the contour geometry, a radius is formed; these radii are advantageous because they improve the release properties of preform 2.

[0076] Figure 5b shows a structural shape 9b. This structural shape 9b is characterized by a contour with a repeating geometry. A key feature of this geometry is that it has a rising and a falling flank, and these flanks are at right angles to each other.

[0077] Figure 5c shows a structural shape 9c. This structural shape 9c is characterized by a contour with a repeating geometry. A key feature of this geometry is that it comprises a circular arc. The center angle in this embodiment is between 45° and 90°.

[0078] Figure 5d shows a structural shape 9d, this structural shape 9d is characterized by the fact that the contour is sinusoidal.

Claims

Claims Method for producing a preform for producing three-dimensional shaped bodies comprising the following process steps: A Production of a preformed part with a shape that is structured at least in some areas and offers increased flexibility for subsequent deformation, comprising at least the following process steps: A.1 Providing an at least two-part preform comprising an upper mold (3) and a lower mold (4), wherein the upper mold (3) and / or the lower mold (4) have on an inner side at least in some areas a negative of the structured shape of the preform part (2) to be achieved, A.2 Blowing in filling material (5) by means of an air flow into the at least two-part preform, wherein the air escapes through openings in the at least two-part preform, so that the blown-in filling material (5) accumulates on the inner sides of the at least two-part preform, or inserting a fleece of filling material; A.3 Connecting and structuring the filling material (5) to form a preform (2) by pressing and / or applying heat and / or by means of a binder; A.4 Opening the at least two-part preform and removing the three-dimensional preform part (2); Method for producing three-dimensional molded bodies according to claim 1, characterized in that the following further method steps are carried out: B Providing the preform part (2) in an at least two-part final mold with a final pressing lower mold (8) and a final pressing upper mold (7), wherein the inner contour the at least two-part final shape corresponds at least partially to the outer contour of the three-dimensional shaped body (1) to be achieved, C pressing the preform part (2) to form the three-dimensional shaped body (1), wherein the preform part (2) forms the three-dimensional shaped body (1) following the structured shaping; D Opening the final mold, which consists of at least two parts, and removing the three-dimensional molded body (1).

3. Method according to claim 1, characterized in that filling material is blown in in method step A.2 until the filling material (5) reaches a degree of compression of greater than 1.5 and less than 2.5 before the connection in method step A.

3.

4. Method according to one of the preceding claims, characterized in that the pressing of the filling material (5) of the three-dimensional shaped body (1) in method step C takes place by pressing the molds of the at least two-part final mold with a contact force of 2000N to 70000N, in particular of 40000N to 50000N.

5. Method according to one of the preceding claims, characterized in that in a method step C.1 before method step C, the preform (2) is heated to a temperature in the range from 100 °C to 200 °C, in particular from 150 °C to 300 °C.

6. Method according to one of the preceding claims, characterized in that fiber material and / or material flakes are blown in as filling material (5), preferably that binding fibers and / or binding material, preferably resin and / or starch, are blown in.

7. Device for producing three-dimensional shaped bodies, characterized in that the device comprises at least: an at least two-part preform for producing a preform part with an upper mold (3) and lower mold (4), wherein the upper mold (3) and / or the lower mold (4) have on an inner side at least in regions a negative of a structured shape to be achieved of the preform part (2), and a two-part final mold with a final pressing lower mold (8) and a final pressing upper mold (7), wherein the inner contour of the at least two-part final mold corresponds at least in regions to the outer contour of the three-dimensional shaped body to be achieved.

8. Device according to claim 6, characterized in that the structure of the at least two-part preform is rib-shaped or wave-shaped or rib-shaped or that the structure of the at least two-part preform has regions with different structures.

9. Device according to one of the preceding device claims, characterized in that the at least two-part preform has different intermediate space volume sections which lead to an uneven deposition of filler material when filling material is blown in.

10. Device according to one of the preceding device claims, characterized in that the at least two-part final shape can be heated to a temperature deviating from the ambient temperature, preferably from 100 °C to 200 °C, in particular from 150 °C to 300 °C.

11. Three-dimensional shaped body (1) produced by a method according to one of claims 1 to 7. Three-dimensional shaped body (1) according to claim 10, characterized in that the shaped body (1) has regions of different wall thickness.

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