METHOD FOR PRODUCING THREE-DIMENSIONAL MOLDED PARTS

Description

[0001] The present invention relates to a method for producing three-dimensional molded parts according to the preamble of the claim.

[0002] On the one hand, three-dimensional molded parts are needed in a wide variety of applications. For example, they are commonly used as insulation components, cladding, vehicle parts, and similar items. It is known that such molded parts can be manufactured from materials including fibers, plastics, polyurethane foams, and metals.

[0003] It is known from the prior art to produce such molded parts from fiber materials to which additives are mixed in order to influence the stiffness and other properties of the molded parts. For example, a method is described in DE 10 324 735 which discloses the preamble of main claim 1.

[0004] On the other hand, the issue of waste disposal and the sensible use or reuse of recycled materials are becoming increasingly urgent. The waste problem plays an ever more important role in both public perception and financial aspects of waste management logistics. However, the targeted recycling rates, especially for packaging materials such as composite packaging, for example in the form of beverage containers, are often not achieved. One reason for this is the lack of suitable uses for the packaging that needs to be recycled.

[0005] With the recycling methods known so far, a complex separation of the paper and film components of the packaging is necessary.

[0006] The present invention is therefore based on the objective of proposing a method that enables the use of recycled materials for the production of three-dimensional molded parts in a simple manner.

[0007] This problem is solved by a method for producing three-dimensional molded parts according to claim 1. Advantageous embodiments are found in dependent claims 2 to 9.

[0008] The inventive method for producing three-dimensional molded parts is carried out, as is known per se, using a multi-part mold. The mold comprises at least a lower mold, an upper mold for blowing in the mold, and a final mold. The mold has openings through which air blown into the mold can escape. The inner surface of the mold at least partially defines the contour of the molded part.

[0009] The procedure comprises the following steps: A. Providing the multi-part mold consisting of the lower mold and the injection mold; B. Injecting mold material elements into the multi-part mold by means of an airflow, whereby the air, as already described, escapes through openings in the multi-part mold so that the mold material elements adhere to the inner surfaces of the multi-part mold; C. Removing the injection mold; D. Placing the upper mold; E. Bonding the mold material elements to each other by applying heat and / or by using a bonding agent; F. Pressing the multi-part mold consisting of the upper and lower molds where recycled material is used as the molded part material elements.

[0010] The invention is thus based on the applicant's finding that any three-dimensional molded parts can be produced from recycled material using the method described above. This provides, firstly, an advantageous way to reuse recycled material in order to recycle it. Secondly, the recycled material represents a cost-effective material for the production of the three-dimensional molded parts.

[0011] Within the scope of the present invention, the term "recycling material" includes lightweight packaging (LVP) made of plastic, aluminum, tinplate or composite materials such as beverage cartons.

[0012] In an advantageous embodiment of the invention, the recycled material is shredded before being blown in. This allows the size of the molded part material elements to be precisely controlled. This improves the quality of the three-dimensional molded parts, since a homogeneous size of the molded part material elements contributes to the quality and stability of the three-dimensional molded parts.

[0013] Preferably, the molded part material elements have a size in the range of 5 mm to 50 mm, preferably 15 mm to 300 mm.

[0014] In a preferred embodiment of the invention, a binder, preferably in the form of a thermosetting powder, is added before and / or during process step B. Alternatively, a binding fiber or thermoplastic film remnants can also be added to the recycled material as a binder. This offers the advantage that recycled material can also be used as a binder. Polyethylene or polypropylene can be used as the fiber material, and epoxy or acrylic or similar materials with a melting point < 220° Celsius can be used as the powder. The binding fibers preferably have a length of between 3 and 60 mm, and the film remnants can be mixed in as flakes of 3 to 50 mm.

[0015] The addition of a binder can improve or control the bonding of the molded part material elements. However, it is equally within the scope of the invention to omit the addition of a binder. When using recycled materials, for example, conventional composite materials such as beverage carton cartons do not require a binder, as the polyethylene they contain acts as a binder, which is preferably activated by the heat generated during the manufacturing process.

[0016] To optimize the properties of the three-dimensional molded part, such as increasing its strength, fiber materials can be added to the recycled material. Preferably, bast fibers, glass, basalt, or aramid can be added to the recycled material before process step B to increase strength. The fibers should have a length of 30–150 mm.

[0017] Preferably, the molded part material elements or the molded part itself are pressed in a single process step, thereby compacting the molded part material elements and increasing the stability of the molded part. Preferably, the pressing takes place in process step F after process step D. However, it is also within the scope of the invention for the pressing to take place during or simultaneously with the placement of the upper mold in process step D. Process step D can therefore also take place after process step E. Alternatively, the pressing can be carried out by an additional process step before or after process step E.

[0018] In a further embodiment of the invention, the joining of the molded part material elements to one another by the application of heat in process step E and the pressing in process step F are carried out using different tools. A change from the blow-in upper mold to the upper mold can take place. Particularly preferably, a molded part blank can be transferred from a first tool to a second tool in an intermediate step after process step F. In the second tool, the molded part blank is then preferably pressed to form the three-dimensional molded part.

[0019] In a further preferred embodiment of the invention, the multi-part mold is heated at least partially before the injection of the mold material elements in process step B. Preferably, the lower and upper molds are heated before process step B. By heating the multi-part molds, the binder in the mold material elements is activated directly after injection and compression, and the mold material elements bond to one another.

[0020] Optionally, an injection frame can be used, which is also part of the multi-part mold. In this case, the multi-part mold consists of the lower mold, the injection upper mold, the injection frame, and the upper mold. Preferably, the molded part material elements and a binder are first injected into the multi-part mold consisting of the lower mold, injection upper mold, and injection frame until the multi-part mold is completely filled. The lower mold preferably defines the lower contour of the three-dimensional molded part.

[0021] The binder is then activated by heat. The molded part material elements bond together. After this step, a molded part blank is available.

[0022] In the next step, the blowing-in upper mold is removed and replaced with the upper mold. The upper mold preferably defines the upper contour of the finished molded part.

[0023] By placing the upper mold, the mold blank is pressed into its final three-dimensional shape. The finished three-dimensional mold can then be removed.

[0024] A device for producing three-dimensional molded parts comprises, as is known per se, a multi-part mold having openings, the inside of which at least partially defines the contour of the three-dimensional molded part. The mold consists of at least a lower mold, an injection mold, and an upper mold. Furthermore, a feed means for blowing molded part material elements into the multi-part mold is provided, as well as means for bonding the molded part material elements by means of a heat supply and / or by means of a feed means for a bonding agent.

[0025] It is essential that the feeding means are designed to blow recycled material into the multi-part mold as molding material elements.

[0026] In a preferred embodiment of the device, the multi-part mold is designed to form a three-dimensional molded part from the molded part material elements made of recycled material.

[0027] To ensure the transport of the recycled material, the feed elements, in particular the supply lines to the injection nozzles of the multi-part mold, are preferably adapted in size. Preferably, the supply lines to the injection nozzles have a diameter of approximately 100-125 mm.

[0028] Typically, additional feeding devices, preferably the material feed rollers in the filling chutes, are fitted with needles. The material feed rollers are preferably fitted with needles in such a way as to prevent them from becoming stuck with the recycled material. For this purpose, the distances between the needles are increased.

[0029] The device also exhibits the aforementioned advantages of the method according to the invention or of the described preferred embodiments of the method according to the invention.

[0030] Preferably, Tetra Pak® material or other recycled material in the form of packaging, beverage cartons or similar is used.

[0031] In a preferred embodiment, the device is configured as follows: The recycling material is shredded in a shredder and transported on a conveyor belt within the device. In an opener within the device, the recycling material is roughly opened, i.e., loosened and spread out, and then transported via the conveyor belt to a distribution station.

[0032] At the distribution station, the mixture is distributed to one or more filling chutes that lead to the multi-part molds. A binder can optionally be added here.

[0033] From the filling chutes, the material is blown through nozzles into the multi-part mold, which at this point consists of a lower mold and an upper blowing mold, as well as an optional blowing frame, using an airflow.

[0034] Once the multi-part mold is filled, the upper mold is removed and the lower mold, containing the blown-in part material elements, is transported to a heating and pressing station. In the heating station, the upper mold is placed on top, and the binder in the part material elements is heated. Typical heating times are 15–100 seconds. The part material elements fuse together, resulting in a molded part blank.

[0035] Simultaneously or after a definable heating period, preferably in the last third of the heating period, the molded part blank is pressed. After pressing, the three-dimensional molded part can be removed from the pressing station. Optionally, the three-dimensional molded part can be punched to a desired final contour if required.

[0036] Further preferred features and embodiments of the method and apparatus according to the invention are explained below with reference to exemplary embodiments and the figures. These exemplary embodiments are merely advantageous configurations of the invention and are not limiting.

[0037] This shows: Figure 1 shows the process steps of an embodiment of the method according to the invention, Figure 2 shows an embodiment of a device according to the invention for the production of three-dimensional molded parts.

[0038] Figure 1Figure 1 shows the process steps of an embodiment of the method according to the invention in several partial illustrations.

[0039] Figure 1a Figure 1 shows a schematic representation of the multi-part mold 1 with sub-mold 3, blowing-in upper mold 2, and a blowing-in frame 4 in process step A. The sub-mold 3 defines the lower contour of the three-dimensional molded part. The blowing-in frame 4 allows the blowing-in upper mold 2 to be placed on top as a temporary auxiliary mold, which differs from the final contour of the molded part. The various parts of the multi-part mold are not airtight; rather, the multi-part mold has openings through which air can escape.

[0040] Figure 1b Figure 1 shows the blowing in of the molded part material elements 5 in process step B. The molded part material elements 5 are deposited inside and on the inner sides of the multi-part mold 1, while the air escapes through openings in the multi-part mold.

[0041] Figure 1c shows a multi-part mold filled with mold part material elements 5.

[0042] In process step D, the blowing-in mold 2 is then removed. This is shown in Figure 1d The upper mold 6 is placed on the mold in process step D. The inner contour of the upper mold 6 defines the upper contour of the subsequent three-dimensional molded part. In process step E, the binder is activated by heat. This causes the molded part material elements 5 to bond together to form a molded part blank.

[0043] By pressing the upper form 6, the mold blank is pressed into the molded part.

[0044] Figure 1e Figure 7 shows the finished three-dimensional molded part after pressing.

[0045] Figure 2 shows a device for carrying out an embodiment of the method according to the invention.

[0046] The device comprises a conveyor belt 10 and a conveyor belt 12. Furthermore, an opener 11 and a transport fan 24 are provided. In the further production process, filling chutes 14 are provided, which are operatively connected to powder dispensers 15.

[0047] Starting from the filling shafts 14, blowers 16 and a heating-pressing station 18 are provided.

[0048] The recycled material is either shredded or delivered already shredded and transported on conveyor belt 10 to the opener 11. There, the recycled material is roughly opened and transported via conveyor belt 12 to the bunker 13 for storage and premixing.

[0049] The recycled material is distributed to the filling chutes 14. A binder, in this case a thermosetting powder, is added to the filling chutes 4 via the powder dispensers 15, if necessary.

[0050] Starting from the filling chutes, the recycled material is blown into the multi-part molds of the injection stations 18. The process is to Figure 1 described in detail.

[0051] For pressing, the filled multi-part mold can be transferred to the heating and pressing station 18. The upper mold is placed on top in the heating and pressing station. There, the thermosetting powder in the filled multi-part mold is heated and then pressed to its final dimensions.

[0052] The finished three-dimensional molded part 7 can be removed from the press station and, if necessary, punched to the final contour using a punch press.

Claims

1. A method for producing three-dimensional molded parts (7) with a multi-part mold consisting of a lower mold, an upper blow mold, and an upper mold (2, 3, 4, 6) with openings, the inner side of which at least partially determines the contour of the molded part (7), comprising the following method steps: A providing the multi-part mold consisting of at least a lower mold and an upper blow mold (2, 3), B blowing molded material elements (5) into the multi-part mold (2, 3, 4, 6) by an air flow, wherein the air escapes through openings in the multi-part mold (2, 3, 4, 6) so that the molded material elements (5) adhere to the inner surfaces of the multi-part mold (2, 3, 4, 6); C removing the upper blow mold (3); D applying the upper mold (6); E connecting the molded material elements (5) to each other by supplying heat and / or by a binder; F pressing the multi-part mold made of upper mold and lower mold (2, 6); characterized in that recycling material is used for the molded material elements (5).

2. The method according to claim 1, characterized in that the recycling material (5) is shredded before blowing.

3. The method according to claim 1 or 2, characterized in that the molded material elements (5) have a size between 5 and 50 mm, preferably in the range between 15 mm and 30 mm.

4. The method according to any one of the preceding claims, characterized in that in a method step G after the method step F, further molded material elements (5) are blown by a second air flow preferably in a second filling run.

5. The method according to any one of the preceding claims, characterized in that before or during the method step B, a binder, preferably in the form of a thermosetting powder or a binding fiber or thermoplastic film residues is added.

6. The method according to any one of the preceding claims, characterized in that before or during the method step B, the fiber material is blown in.

7. The method according to any one of the preceding claims, characterized in that the molded material elements (5) and / or the molded part (7) are pressed in method step G, so that the molded material elements (5) are compacted.

8. The method according to any one of the preceding claims, characterized in that the connecting of the molded material elements (5) to each other by applying heat in method step E and pressing in method step G is performed in different tools, in particular in that the molded blank is transferred from a first tool to a second tool in an intermediate step.

9. The method according to any one of the preceding claims, characterized in that the multi-part mold (2, 3, 4, 6) is heated at least partially before blowing in the molded material elements (5) in method step B, preferably in that the lower mold and upper mold are heated before method step B.