Additively manufactured components of an extruder

Abstract

The invention relates to an extruder consisting of several components, wherein between the components, a medium is kneaded, mixed and / or conveyed in the extrusion direction, wherein at least two of the components are at least partially in engagement with one another. According to the invention, at least one of the components is constructed in a computer-supported manner, computer-supported production data are available for this component and on the basis of said production data the component is additively manufactured, wherein the components manufactured in this manner fulfil at least one of the following functionalities: • ideal dispersion of the medium • thermal homogenisation with a targeted temperature control of the medium • mechanical homogenisation of the medium • melting of the medium. The invention also relates to a related method and to a component.

Description

[0001] Additively manufactured components of an extruder

[0002] Description:

[0003] The invention relates to an extruder consisting of several components, wherein a medium is kneaded, mixed, and / or conveyed in the extrusion direction between the components, with at least two of the components at least partially engaging with each other. Furthermore, the invention relates to a method for producing the component and the component itself.

[0004] Such devices are known from the state of the art. For example, in the article published on Chemitechnik.de on September 8, 2011, Thomas Malzahn describes a device for dispersing and controlled temperature control of plastic polymer mass in a planetary roller extruder.

[0005] The planetary roller extruder's mechanism resembles a planetary gear with extremely wide gear teeth and spiral teeth. As the central spindle rotates, the planetary spindles roll on the central spindle and the internally toothed roller cylinder, rotating in a planetary-like fashion. During this process, the material is gripped, rolled out into thin layers by the spindle teeth engaging the corresponding tooth gaps, and transported forward by the spiral teeth. This repeated thin-layer rolling enables precise temperature control and dispersion throughout the entire processing process.

[0006] By manufacturing cylinder liners using deep discharge machining, cylinder liners with a special, minimized wall thickness can be manufactured. The thin outer wall enables improved temperature control of the medium via the cylinder liner.

[0007] But especially in the case of the cylinder liner with the twisted internal toothing, there are clear manufacturing limitations with regard to the toothing design (module; pitch changes; targeted barrage; toothing with opposite pitch; etc.).

[0008] The space available for machining the inner cylinder surface significantly limits geometric design options.

[0009] This means that with a plant roller extruder, the design of the processing unit cannot be as individually tailored to the process engineering requirements as is the case with single and twin screw extruders today.

[0010] The advantages of interlocking components with different geometries along their length were already disclosed in Kunststoffe 05 / 2005 from Carl Hanser Verlag. This article describes a multi-zone screw in which a pair of screws is replaced by a central screw, into which a smaller screw engages on opposite sides. The object of the invention is to enable and simplify the production of complex components in extrusion technology in such a way that process engineering requirements can be implemented and manufacturing costs and production time for the components can be minimized. Furthermore, the object includes offering an extruder using the manufactured components and a corresponding process for producing such components.

[0011] The solution to the problem with regard to the device is characterized in conjunction with the preamble of claim 1 in that at least one of the components is designed with computer support, computer-aided manufacturing data prevail for this component and on the basis of these manufacturing data the component is manufactured additively, wherein the components thus manufactured fulfill at least one of the following functionalities:

[0012] • ideal dispersion of the medium,

[0013] • thermal homogenization with targeted temperature control of the medium,

[0014] • mechanical homogenization of the medium,

[0015] • Melting the medium.

[0016] A variety of interlocking components are possible and can be manufactured according to the invention. Thus, for example, the components of a planetary roller extruder can be adapted much more precisely to the process requirements, analogous to the screw designs of single- and twin-screw extruders.

[0017] What is essential is that the invention can be used to produce components that cover at least the functionalities specified in the claim or a combination of these. From the components designed using CAD, computer-aided manufacturing data is generated, which, similar to the production of parts using CNC machines, is used for the additive manufacturing of the components. In additive manufacturing, material is applied layer by layer, thus creating a three-dimensional object.

[0018] Additive manufacturing, also known as 3D printing, allows for the production of highly complex components, as accessibility to joints during assembly of individual components no longer needs to be considered. Furthermore, traditional consideration of component manufacturability plays a subordinate role, as additive manufacturing creates new possibilities for producing even highly complex designs using this process.

[0019] According to the further development, the contour and / or geometry is intended to change over the length of the additively manufactured component. This has the advantage of influencing the transport behavior in such a way that different residence times can be realized within a build segment. In particular, with PWE, gaps in the gearing are generally used. The planetary spindle can move freely within this gap. Using the options described here, the freedom of movement of the planetary spindle can be restricted. Another advantage is that, similar to the multi-zone screw, different process steps such as pressure build-up, melting, thermal and mechanical dispersion can be realized over the screw length in the single or twin-screw extruder.

[0020] According to a further development, the contour, which changes over the length of the additively manufactured component, includes a modified toothing, whereby the pitch of this toothing can change continuously, linearly, progressively, degressively, or abruptly. This has the advantage of being compact and flexible in the implementation of process-related specifications.

[0021] It is advantageous if the invention is implemented in a planetary roller extruder which consists of a planetary roller cylinder, a central spindle and several planetary spindles, wherein the planetary spindles are at least partially engaged with both the central spindle and the planetary roller cylinder.

[0022] Different pitches can be used within a planetary roller system, or even opposing pitches can be used. The transitions can be smooth or abrupt, which is only possible with the additive manufacturing process according to the invention. The basic geometry can remain constant but can also be changed, thereby changing the gearing module. However, a completely different design is also conceivable using additive manufacturing.

[0023] According to a further development, it is proposed to partially design the planetary spindle without any gearing, so that it only comprises a general, for example, cylindrical, geometry. The planetary spindle is then still securely guided in the system, but significantly narrower gaps are created, which can be beneficial for fulfilling the required functionalities according to the invention. The currently known dams can also be realized by a large-diameter cylindrical section on the planetary spindle. An advantage over the prior art is that with the dams realized by a large-diameter cylindrical section on the planetary spindle, the invention can thus create a dynamic dam that is significantly easier to clean.

[0024] The planetary spindle can also be complex and completely or partially hollow. This creates, among other things, a larger volume and achieves better mixing, while retaining the toothing.

[0025] This of course applies to one or more planetary spindles.

[0026] According to a further development, the additive manufacturing of components according to the invention makes it possible to provide certain components with openings that can be used as temperature control channels, for injection, degassing, or for other functions. There are hardly any limits to the design of such openings. Conventional holes are always cylindrical and straight; through additive manufacturing, these holes can be changed in diameter or be curved, thus adapting them to the requirements of the desired function. A further advantage is that no additional seals are required. These openings can be used, for example, to conduct air or water, or they can be used for measurement technology.

[0027] The solution to the problem regarding the method is set out in claim 9. Regarding the functionalities to be fulfilled, it is important to ensure that they are fulfilled within a specific time frame, because depending on the material used, this may be damaged if the fulfillment of the functionalities takes too long. For example, some plastics can be thermally damaged if the residence time is too long, or if foodstuffs are mixed with fats in the extruder, these fats become unusable.

[0028] The solution to the problem regarding the product is given in claim 10.

[0029] Ideally, the computational geometry is created using a targeted flow simulation. This can be repeated multiple times to improve the geometry in agile processes. Only in this way can the desired goals be achieved in advance: homogeneous melting, cooling and heating, and dispersion as optimally as possible.

[0030] Advantageous further training results from the subclaims.

[0031] The drawings show schematically a device according to the invention:

[0032] Fig. 1 shows symbolically an extruder,

[0033] Fig. 2 shows schematically a planetary roller extruder,

[0034] Fig. 3 shows a section according to Figure 2,

[0035] Fig. 4 shows schematically two complex components in engagement and

[0036] Fig. 5 shows an example of a partial section through a complex planetary roller part

[0037] Fig. 6 example of a complex planetary roller part with a planetary spindle without complete toothing

[0038] Fig. 7a-d show exemplary embodiments of a complex planetary spindle

[0039] Figure 1 shows an extruder 1 with a first component 2, which is illustrated here as an extruder housing constructed from several sleeves, and a second component 3, which also shows an extruder screw, which is set in rotation by means of a drive 5. Medium is added to the extruder 1 via the feed hopper 4, which medium is kneaded, mixed, and / or conveyed in the spaces between the components in the extrusion direction 6 to the end of the extruder 1, where it undergoes further processing.

[0040] Figure 2 shows an example of an extruder 1 designed as a planetary roller extruder 7. The first component 2 of the extruder 1 is a planetary cylinder 8, and the second component 3 is a planetary spindle 10. The planetary spindle 10 meshes with the planetary roller cylinder 8 via its gearing 11, thus engaging these two components. The planetary spindle 8 also meshes with the central spindle 9, so that in this embodiment, three components are engaged with each other.

[0041] Figure 3 essentially corresponds to Figure 2; identical components are again labeled with the same reference numerals. Here, too, a planetary roller extruder is shown, but in a sectional view. This sectional view shows a design in which the gearing 11 is varied along the length of components 2 and 3. Three different gearings A, B, and C are shown as examples, which are labeled 12, 13, and 14. Such complex designs are very difficult to manufacture. With regard to the external geometry, as required for the planetary spindle 10 or the central spindle 9, this may still be feasible under certain circumstances. With regard to the internal geometry, as required for the planetary roller cylinder 8, conventional manufacturing (turning, erosion, etc.) reaches its limits due to a lack of accessibility.Additive manufacturing does not have such limitations, as the layered structure allows almost any conceivable contour to be produced.

[0042] Figure 4 again shows a first component 2, which meshes with a second component 3 via the gear teeth. Both components 2 and 3 have different gear teeth A, B, and C, which are again designated by reference numerals 12, 13, and 14.

[0043] In the illustration according to Figure 5, only the planetary roller cylinder 8 is shown in section. Consequently, the complex structure with very different gearing of the central spindle 9 and the planetary spindle 10 can be seen. Here, too, the different gearings A, B, and C are marked with the reference numbers 12, 13, and 14.

[0044] In all figures depicting a planetary roller extruder 7, only one planetary spindle 10 has been shown for clarity. Of course, the invention also encompasses embodiments in which multiple planetary spindles 10 are arranged around the central spindle 9 and engage with the central spindle 9 and, if appropriate, also with the planetary roller cylinder 8. Several modules depicted in this way can be arranged one behind the other in series in the extrusion direction, thus providing a very complex extruder 1.

[0045] Planetary roller extruders are typically used with meshing gear geometries, where the gear geometry has a pitch, commonly called helical gearing. The profile and pitch of these geometries are usually essentially constant over the length of the component. It is common for individual teeth or even multiple teeth to be completely or partially removed. It is also known for an additional geometry to be introduced (a nub spindle).

[0046] Figure 6 shows a schematic representation of a geometry in which the components, as in Figures 2 to 5, do not have a constant pitch. Identical components are again marked with the same position numbers. Different pitches can be used within a planetary roller system, or they can have opposing pitches. The transitions can be smooth or abrupt, which in turn is only possible using additive manufacturing processes. The basic geometry can remain constant, but can also be changed, for example by changing the gear module, or it can be designed completely differently, as shown here. This design is just an example, but a multitude of freely createable geometries are conceivable. For example, a simple circular geometry can be created for a planetary spindle, which is then no longer in mesh with each other (item15), i.e. no longer mesh with each other, just as any other geometry can be mapped, provided the kinematics of the rotating parts allow it.

[0047] Figure 7a shows a planetary spindle 10 with a cavity 16 in which an additional spindle 17 predominates. This additional spindle 17 is integrated into the planetary spindle 10 and, so to speak, floats within it. Due to additive manufacturing, the planetary spindle 10 can be a single piece and closed on both sides, since the additional spindle 17 does not need to be assembled. This creates a larger volume to achieve improved mixing. The gearing is retained.

[0048] The inner contour can be freely designed, especially in the adaptive process:

[0049] This design is ideal for adaptive manufacturing, but is not limited to planetary roller extruder components. It is also conceivable to combine such a hollow shape with conventional extruder screw geometries, for example, for shearing and mixing parts.

[0050] List of reference symbols:

[0051] 1 extruder

[0052] 2 First component of the extruder

[0053] 3 Second component of the extruder

[0054] 4 filling funnels

[0055] 5 Drive

[0056] 6 Extrusion direction

[0057] 7 planetary roller extruders

[0058] 8 planetary roller cylinders

[0059] 9 Central spindle

[0060] 10 planetary spindle

[0061] 11 Gearing

[0062] 12 Gearing A

[0063] 13 Gearing B

[0064] 14 Gearing C

[0065] 15 geometry out of 10 that is no longer in engagement

[0066] 16 cavity in 10

[0067] 17 Additional spindle

Claims

Patent claims:

1. Extruder (1) consisting of several components, wherein a medium is kneaded, mixed and / or conveyed in the extrusion direction (6) between the components (2, 3), wherein at least two of the components are at least partially engaged with each other, characterized in that at least one of the components (2, 3) is designed with computer support, computer-aided manufacturing data predominates for this component (2, 3), and the component is additively manufactured on the basis of these manufacturing data, wherein the components thus manufactured fulfill at least one of the following functionalities: • ideal dispersion of the medium, • thermal homogenization with targeted temperature control of the medium, • mechanical homogenization of the medium, • Melting the medium.

2. Extruder according to claim 1, characterized in that the contour and / or the geometry can be changed over the length of the additively manufactured component (2, 3).

3. Extruder according to claim 2, characterized in that the contour changing over the length of the additively manufactured component (2, 3) comprises a modified toothing (11).

4. Extruder according to claim 3, characterized in that the toothing (11) which changes over the length of the additively manufactured component (2, 3) comprises the pitch, wherein the pitch changes continuously, linearly, progressively, degressively or abruptly.

5. Extruder according to claim 1, characterized in that the extruder (1) is a planetary roller extruder (7), consisting of a planetary roller cylinder (8), a central spindle (9) and several planetary spindles (10), wherein the planetary spindles (10) are at least partially engaged with both the central spindle (9) and the planetary roller cylinder (8).

6. Extruder according to claim 5, characterized in that the planetary spindle (10) partially has no toothing and thus only comprises a general geometry there.

7. Extruder according to claim 5, characterized in that the planetary spindle (10) is complex in construction and is completely or at least partially hollow.

8. Extruder according to one of the preceding claims, characterized in that the component (2, 3) has one or more openings which can be used as a tempering channel, for injection, for degassing or for other functions.

9. A method for producing a component for an extruder according to claim 1, characterized in that the component (2, 3) is designed with computer support, computer-aided production data are generated therefrom, the component (2, 3) is additively manufactured on the basis of these production data, wherein the component thus manufactured fulfills at least one of the following functionalities: • ideal dispersion of a medium, • thermal homogenization with targeted temperature control of the medium, • mechanical homogenization of the medium • Melting the medium.

10. Component of an extruder according to claim 1, characterized in that the component (2, 3) is designed with computer support and thus computer-supported manufacturing data predominates and the component (2, 3) is manufactured additively on the basis of these manufacturing data.

11. Component according to claim 10, characterized in that the component (2, 3) has one or more openings which are used as a temperature control channel, for injection, for degassing or for other functions.

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