WO2024099777A1

WO2024099777A1 - Three-dimensional moulded body, device and method for producing a three-dimensional moulded body

Info

Publication number: WO2024099777A1
Application number: PCT/EP2023/079821
Authority: WO
Inventors: Egon FÖRSTER
Original assignee: Fiber Engineering Gmbh
Priority date: 2022-11-07
Filing date: 2023-10-25
Publication date: 2024-05-16
Also published as: DE102022129362A1

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

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

Description

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

Known three-dimensional molded bodies are made of filler material that is blown into a multi-part mold by an air flow. The filler material is deposited on the inner wall of the mold and is bonded by pressing and/or heat supply and/or a binding agent. Such molded bodies have the advantage that individual three-dimensional shapes can be produced that are light on the one hand and stable on the other. Three-dimensional molded bodies are used, for example, for soundproofing, thermal insulation or in the automotive industry. The molded bodies can be used to cover vehicle interiors or as supports. Usually, one-piece parts with the largest possible surface area are used. Fiber material, material flakes or binding fibers are used as filler material. Resin and/or starch are used as binding material.

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. The content of these documents is explicitly referred to, particularly with regard to the manufacturing process, in order to avoid repetition.

Alternatively, airlaid processes are known from the state of the art for the production of fiber fleeces. In these processes, the fibers are pressed into fiber fleeces by rollers. The disadvantage of the previously known molded bodies from the state of the art is that they require a production-related Must have a minimum wall thickness, which does not allow 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 filler material and on the other hand to the difficult handling of particularly thin-walled molded bodies during the manufacturing process.

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.

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.

This object is achieved by a method for producing a preform for producing a three-dimensional molded body according to claim 1 and a device for producing a three-dimensional molded body according to claim 6 and 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.

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.

The method according to the invention for producing a preform for the production of a three-dimensional molded body comprises the following method steps:

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:

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 are have at least in some areas a negative of the structured shape of the preform to be achieved,

A.2 Blowing filling material into the at least two-part preform by means of an air flow, the air escaping 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 made of filling material;

A.3 Joining and structuring the filling material to form a preform by pressing and/or applying heat and/or by means of a binding agent;

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

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 part to be achieved.

This results in the advantage according to the invention that the region-wise structured shaping of the preform part enables increased flexibility of the preform part for subsequent deformations.

Within the scope of the invention, the structured shape can be viewed as a surface profile with which the preformed part is to be provided in some areas or is provided after its manufacture. In particular, the surface profile can comprise a plurality of profile elements which are to be or are formed at least in some areas in a regular arrangement on the preformed part. In particular, the profile elements can each be elongated, i.e. with a main extension axis.

The surface profile can be designed to influence a mechanical property, in particular a dimensional rigidity, of the preform part in comparison to an unstructured, in particular unprofiled, component area of the preform part. In particular, this can result in an anisotropic Form stiffness can be adjusted, whereby the form stiffness around and/or along a first axis is higher than around and/or along a second axis. An advantage that can be achieved in this way can be that the preform part has increased flexibility in some areas and can be removed from the preform with little effort by deforming this area. At the same time, the preform part can have increased stiffness in some areas, so that this area is not or only slightly deformed when the preform part is removed from the preform. This improves the handling of the preform part, which particularly facilitates handling using an automated handling device.

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 relative to a rotation axis, so that the preform is conical. The wall also has a structured shape, with the above-mentioned profile elements being elongated and running between the base and the opening. The profile elements also each have a height profile along their respective longitudinal axis, with the height of the profile elements being lower in the area of the base than in the area of the opening. The profile elements can be formed on an inner and/or outer side of the wall. The preform is accordingly formed at least in some areas as a negative of the shape of the preform described above. In particular, the profile elements can each have a pointed edge and/or rounded cross section, for example in the form of a triangle, a curve or a wave section.

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

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

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

In an advantageous embodiment of the method, the filling material which is blown in in process step A.2 reaches a degree of compression of greater than 1.5 and less than 2.5 before being connected and structured in process step A.3. The degree of compression describes the ratio of the blown-in density of the filling material to the loose bulk density of the filling material.

The advantage of 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.

In an advantageous embodiment of the method, the filling material of the three-dimensional molded body is pressed in method 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, for example yoghurt cups, preferably 1,500 N to 3,000 N, alternatively preferably for larger molded parts from 10,000 N to 70,000 N, preferably 40,000 N to 70,000 N.

By pressing the filling material of the three-dimensional molded body with the contact force, which leads to compaction, a dimensionally stable preformed part is formed. Compaction can take place locally or affect the entire fiber molded part. For this purpose, for example, an auxiliary mold can be placed on top that has a different inner contour and thus leads to a locally different density distribution. This process is described in DE 10 324 735 B3. Reference is hereby made to the details of the process, in particular with regard to the creation of an inhomogeneous density distribution. In a preferred embodiment, fiber material and/or material flakes are blown in as filler material, preferably binding fibers and/or binding material, preferably resin and/or starch, are blown in. The ratio of binding fiber/binding powder to the fibers usually 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.

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

The advantage here is that the binding fibers of the filling material change their material properties when the preform is heated: This change leads to the activation of the binding property by reaching the melting point of the binding material. This melting point of the binding material is therefore decisive for the temperature window in process step C.1.

Preferably, in process step C, which includes pressing the preform part to form the three-dimensional molded body, the structured shape on the preform part 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 part does not have to be embodied in the three-dimensional molded body produced. In this respect, for example, visible surfaces or functional surfaces of the molded part to be produced can only be provided with the structured shape during the production of the preform part in order to achieve the desired advantages for handling without the appearance or function of the molded body to be produced being impaired.

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.

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 on an inner side at least in regions a negative of a structured shape of the preform part to be achieved. The device further comprises at least one 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 in regions to the outer contour of the three-dimensional molded body to be achieved.

It is essential that this device comprises a preform and a final form. The preform is used to produce a preform part which has different properties than the three-dimensional molded body produced using the final form. The preform part is characterized by its flexibility, which is present despite its dimensional stability. The flexibility is created by the shaping structure formed in certain areas on the upper mold and/or the lower mold. The structured shaping creates the flexibility by adding a surface area. This can be understood as a local excess of material in the preform part, which can be compressed and/or distributed when the three-dimensional molded body is pressed in order to form a substantially flat surface of the three-dimensional molded body. The surface area addition therefore makes it possible to form the three-dimensional molded body using the final form. The advantage is that thin-walled three-dimensional molded bodies can be formed which have a high or low material density in certain areas.

The method according to the invention is preferably designed to be carried out by means of the device according to the invention and/or a preferred embodiment thereof. The device according to the invention is preferably designed to carry out 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 the structure of the two-part preform) is ripple-shaped, wave-shaped or rib-shaped. Alternatively, the structure of the at least two-part preform can have regions with different structures.

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

An advantageous embodiment of the at least two-part preform has different space volume sections. These different space volume sections arise from a changing distance between the lower mold and a blowing lower mold. The different space volume sections allow for uneven filling material deposition when the filling material is blown in. After blowing in, the blowing upper mold is preferably removed and replaced by an upper mold.

An advantage of this design is that a targeted material reinforcement of the preformed part can be achieved in specific areas. This targeted reinforcement serves to increase the stability of the three-dimensional molded body.

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.

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.

The above-described object is further achieved by a three-dimensional shaped body according to claim 10. The three-dimensional molded body according to the invention is made of a filling material. The three-dimensional molded body is produced according to the invention using the method described above and the device described above.

It is essential that the three-dimensional molded body is produced from a preform.

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

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.

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

The three-dimensional molded 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 molded bodies are used or produced which are to have special properties, for example with regard to thin wall thicknesses and high material densities.

The fiber molded part according to the invention is therefore preferably designed for use in packaging technology. The wall thicknesses that can be achieved are, for example, in a range 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 leftover leather fibers or shredded packaging material, can be used as filling material. These can have properties such as food safety, such as industrially produced cellulose fibers and flakes, or biologically tanned leather fibers.

Further advantageous features and embodiments of the method according to the invention and the device according to the invention are explained below using exemplary embodiments and the figures.

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

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 part for producing a three-dimensional molded body according to the invention;

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

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

Figure 5 with the partial images a to d shows a schematic sectional view of various 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 the partial images a to i shows the method steps of an embodiment of a method according to the invention.

To produce three-dimensional molded bodies, a preform is first produced, shown in the partial 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 in a final shape to form the three-dimensional molded body, shown in the partial figures 1g to 1i.

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

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.

In this case, the lower mold is round and has a zigzag geometry in an outer area around a free round inner area. This zigzag geometry determines the later structured shape of the preform part 2.

In method 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.

The filling material used here is fibers made from hemp, leather waste fibers, cellulose or viscose, or mixtures thereof. A thermoplastic binder is added to the fibers, in the form of powder in grain sizes from 0.1 mm to 0.5 mm or binding fibers in lengths from 3 mm to 51 mm.

The fiber material is deposited in the space between the inner sides of the upper and lower molds. The excess air is Air outlet openings, which are not shown for reasons of clarity, are left out of the preform.

In process step A.3, the filling material 5 is connected and structured to form a preformed part by pressing and/or supplying heat and/or by a binding agent;

This enables the production of a preform with a structured wall that offers greater flexibility for subsequent deformation by pressing. The preform is formed in a circular shape by the lower mold described as an example and in this case has a zigzag structure in an outer area, similar to a muffin mold.

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

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.

The two-part final mold has an inner contour that corresponds to the outer contour of the three-dimensional molded body 1 to be achieved. In the present case, the final press bottom mold 8 is cup-shaped and the final press top mold 7 is fitted as a negative to the final press bottom mold 8.

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

In the following process step C, the preform part 2 is pressed into the three-dimensional molded body 1, wherein the preform part 2 forms the three-dimensional molded body 1 following the structured shaping, 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.

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.

The design of the upper mold 3a is shown in Figures 2b and 2a in a sectional view. The design of the upper mold is shown here schematically as a trapezoid. The trapezoid shape determines the shape of the preform to be produced, since the trapezoid contour is crucial for the formation of the interspace volume, which leads to a targeted deposit of filler material during the process step of blowing in the filler material. The 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 escape. So that the filler material can accumulate within the interspace volume and is not carried out of the at least two-part preform with the air stream, the openings 3a.1 are chosen to be correspondingly small.

In order to avoid repetition, only the differences between Figures 2c to 2e and Figures 2a and 2b will be discussed below.

Figure 2c shows a version of the upper mold 3b that has additional bevels. These gradations lead to a change in the resulting gap volume.

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 an embodiment of the upper mold 3d, which is shown schematically as rectangular. This embodiment does not show any positive contour for shaping.

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 binding agent. The preform part 2 has sections which are 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 areas marked with A. Figure 3b shows a plan view which shows the areas with the zigzag-shaped structure.

Figure 4 shows a schematic representation of a three-dimensional molded body 1 according to the invention. The molded body 1 is manufactured in process step C from the preform 2. By attaching it to the outer contour shape and pressing it, 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. As a result of 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 has a higher material density of the wall.

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 decisive factor for the shape is the external contour of the structural shape 9, which forms the actual structure. Figure 5a shows a structural form 9a. This structural form 9a is characterized by the fact that the contour has a repeating geometry. The essential feature of this geometry is that it has a rising and a falling flank, these flanks are at right angles to each other. A radius is formed at the intersection points of the rising and falling flanks of the contour geometry. These radii are advantageous because they improve the release properties of the preform 2.

Figure 5b shows a structural form 9b. This structural form 9b is characterized by the fact that the contour has a repeating geometry. The essential feature of this geometry is that it has a rising and a falling flank, these flanks are at right angles to each other.

Figure 5c shows a structural form 9c. This structural form 9c is characterized by the fact that the contour has a repeating geometry. The essential feature of this geometry is that it has a circular arc. The central angle in this embodiment is between 45° and 90°.

A structural form 9d is shown in Figure 5d. This structural form 9d is characterized by the fact that the contour is sinusoidal.

Claims

Claims Method for producing a preform for producing three-dimensional molded bodies comprising the following process steps:

A Manufacturing a preform 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 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) is deposited 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 supplying heat and/or by means of a binding agent;

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 form with a final press lower mold (8) and a final press 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 mould, which consists of at least two parts, and removing the three-dimensional moulded 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 is carried out 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 the 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 molded 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 press lower mold (8) and a final press 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 molded body to be achieved.

8. Device according to claim 6, characterized in that the structure of the at least two-part preform is corrugated 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 filling 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 molded 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 thicknesses.