DE102022127575A1 - Additively manufactured components of an extruder - Google Patents

Abstract

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, wherein at least two of the components are at least partially in engagement with one another. According to the invention, it is provided that at least one of the components is designed with computer support, computer-supported manufacturing data predominates for this component and the component is additively manufactured on the basis of this manufacturing data, wherein the components manufactured in this way 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 of the medium. The invention also relates to a related method and a component.

Description

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, wherein at least two of the components are at least partially in engagement with one another. The invention further relates to a method for producing the component and the component itself.

Such devices are known from the state of the art. For example, in the Internet publication on Chemitechnik.de, in the report from September 8, 2011 by Thomas Malzahn, a device for dispersing and specifically controlling the temperature of plastic mass in a planetary roller extruder is described.

The device of the planetary roller extruder resembles a planetary gear with an extremely wide toothing and a spiral toothing. When the central spindle rotates, the planetary spindles roll on the central spindle and the internally toothed roller cylinder and rotate like a planet. During this process, the material is captured, rolled out into thin layers by the spindle teeth dipping into the corresponding tooth gaps and transported forward with the help of the spiral toothing. This repeated thin-layer rolling enables precise temperature control and dispersion throughout the entire processing process.

By manufacturing cylinder liners using deep erosion, cylinder liners can be manufactured with a special wall thickness minimization. The thin outer wall enables improved temperature control of the medium via the cylinder liner.

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.).

The space available for machining the inner cylinder surface considerably limits geometric design options.

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

The advantages of interlocking components with a different geometry along their length were already disclosed in Kunststoffe 05/2005 by Carl Hanser Verlag. There, a multi-zone screw is described in which a pair of screws is replaced by a central screw, into which a small screw engages on each opposite side.

The object of the invention is to enable and simplify the production of complex components using extrusion technology in such a way that process engineering requirements can be implemented and manufacturing costs and production time of the components can be minimized. The object also includes offering an extruder using the components produced and a corresponding process for producing such components.

• • ideale Dispergierung des Mediums,
• • thermisches Homogenisieren mit einer gezielten Temperatursteuerung des Mediums,
• • mechanisches Homogenisieren des Mediums,
• • Aufschmelzen des Mediums.

The solution to the problem with regard to the device is characterized in connection with the preamble of claim 1 in that at least one of the components is designed with computer support, computer-supported manufacturing data prevail for this component and the component is additively manufactured on the basis of this manufacturing data, wherein the components manufactured in this way 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 of the medium.

A large number of components are possible which are in contact with one another and can be manufactured according to the invention. For example, the components of a planetary roller extruder can be adapted to the process engineering requirements much more closely. Analogous to the screw designs of single and twin screw extruders. It is important that the invention can be used to produce components which can 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 is used for the additive manufacturing of the components in a similar way to the manufacture of parts using CNC machines. In additive manufacturing, material is applied layer by layer, thus creating a three-dimensional object.

Using additive manufacturing, also known as 3D printing, very complex components can be manufactured, since accessibility to connection points does not have to be taken into account when assembling individual components. The traditional consideration of the manufacturability of the component plays a subordinate role, since additive manufacturing creates new possibilities for producing even very complex designs using this process.

According to the development, the contour and/or geometry is designed 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 dwell times can be realized within a construction segment. In the case of PWE in particular, gaps in the gearing are usually used. The planetary spindle can move freely within this gap. The freedom of movement of the planetary spindle can be restricted using the options described here. Another advantage is that, analogous to the multi-zone screw, different process steps, e.g. pressure build-up, melting, thermal and mechanical dispersion, can be realized over the screw length in the single or double-screw extruder.

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

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 in engagement with both the central spindle and the planetary roller cylinder.

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

According to a further development, it is proposed to partially design the planetary spindle without any gearing, so that it only has a general geometry, for example a cylindrical one. The planetary spindle is then still guided safely in the system, but much narrower gaps are created, which can be beneficial for the fulfillment of required functionalities according to the invention.

The weirs known today can also be implemented using a large-diameter cylinder section on the planetary spindle. The advantage over the state of the art is that, in the case of weirs implemented using a large-diameter cylinder section on the planetary spindle, the invention enables a dynamic weir to be implemented that is much easier to clean.

The planetary spindle can also be complex and completely or partially hollow. This creates a larger volume and achieves better mixing, but the gearing is retained.

This of course applies to one or more planetary spindles.

According to a further development, the additive manufacturing of the components according to the invention means that certain components can already be provided with openings that can be used as temperature control channels, for injection, for degassing or for other functions. There are hardly any limits to the design of such openings. Conventional holes are always cylindrical and straight, but additive manufacturing allows them to change their diameter or be bent, i.e. to be adapted to the requirements of the desired function. Another advantage is that no additional seals are required. Air or water can be fed through these openings, for example, or they can be used for measurement technology.

The solution to the problem with regard to the method is given in claim 9. It is important to ensure that the functionalities to be fulfilled are fulfilled within a certain 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 dwell time is too long, or if foodstuffs are mixed with fats in the extruder, these then become unusable.

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

Ideally, the computer-aided geometry is created using a targeted flow simulation. This can be repeated several times to improve the geometry in agile processes. This is the only way to ensure in advance the desired objectives: homogeneous melting; cooling and heating as well as dispersion as optimally as possible.

Advantageous further developments arise from the subclaims.

• 1 zeigt symbolisch einen Extruder,
• 2 zeigt schematisch einen Planetwalzenextruder,
• 3 zeigt einen Schnitt gemäß 2,
• 4 zeigt schematisch zwei im Eingriff stehende komplexe Bauteile und
• 5 zeigt beispielhaft einen Teilschnitt durch ein komplex bauendes Planetwalzenteil
• 6 beispielhaft komplex bauendes Planetwalzenteil mit einer Planetpindel ohne komplette Verzahnung
• 7a-d zeigen beispielhaft Ausführungsformen einer komplexen Planetspindel

The drawings show schematically a device according to the invention:

• 1 symbolically shows an extruder,
• 2 shows schematically a planetary roller extruder,
• 3 shows a section according to 2 ,
• 4 shows schematically two complex components in engagement and
• 5 shows an example of a partial section through a complex planetary roller part
• 6 exemplary complex planetary roller part with a planetary spindle without complete gearing
• 7a -d show exemplary embodiments of a complex planetary spindle

1 shows an extruder 1 with a first component 2, which is shown here as an example of an extruder housing made up of several sleeves, and a second component 3, which also shows an example of an extruder screw that is set in rotation by means of a drive 5. Medium is added to the extruder 1 via the filling funnel 4, which medium is kneaded in the spaces between the components, mixed and/or conveyed in the extrusion direction 6 to the end of the extruder 1, where it is subjected to further processing.

2 shows an example of an extruder 1 that is 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 by means of its gearing 11, so that these two components are in engagement with one another. The planetary spindle 8 also meshes with the central spindle 9, so that in this embodiment even three components are in engagement with one another.

3 essentially corresponds to the 2 , identical components are again marked with the same reference number. Here, too, a planetary roller extruder is shown, but in a sectional view. In this sectional view, a design is shown in which the gearing 11 is changed over the length of the components 2, 3. As an example, three different gearings A, B and C are shown here, which are marked with the reference numbers 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 possible under certain circumstances. With regard to the internal geometry, as required for the planetary roller cylinder 8, classic production (turning, erosion, etc.) reaches its limits due to a lack of accessibility. Additive manufacturing does not have such limits, since the layer-by-layer structure means that almost any conceivable contour can be produced.

4 again shows a first component 2 which is in engagement with a second component 3 via the gear teeth. Both components 2, 3 have different gear teeth A, B and C which are again identified with the reference numbers 12, 13 and 14.

In the representation according to 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.

In all figures in which a planetary roller extruder 7 is shown, only one planetary spindle 10 is shown for the sake of clarity. Of course, the invention also includes embodiments in which several planetary spindles 10 are arranged around the central spindle 9 and engage with the central spindle 9 and, if necessary, also with the planetary roller cylinder 8. Several modules shown in this way can be arranged one behind the other in series in the extrusion direction and thus provide a very complex extruder 1.

Planetary roller extruders are generally used with meshing gear geometries, whereby the gear geometry has a pitch, usually called helical gearing. The profile and pitch of these geometries are usually essentially constant over the length of the component. It is known that individual teeth or even several teeth are completely or partially removed. It is also known that an additional geometry is introduced (knob spindle).

In 6 , a geometry is presented schematically in which the components, as in the 2 to 5 , do not have a constant pitch. The same components are marked with the same position numbers. Different pitches can be used within a planetary roller system or they can have opposite pitches. The transitions can be smooth or abrupt, which in turn can only made possible by additive manufacturing processes. The basic geometry can remain constant, but can also be changed, for example by changing the gear module or by designing it completely differently, as shown here. This version is just an example, but a large number of freely created geometries are conceivable. For example, a simple circular geometry can be created for a planetary spindle that is then no longer in engagement with one another (item 15), i.e. no longer meshes with one another, just as any other geometry can be reproduced, provided the kinematics of the rotating parts allow it.

In 7a a planetary spindle 10 is shown which has a cavity 16 in which an additional spindle 17 predominates. This additional spindle 17 is integrated in the planetary spindle 10 and floats in it, so to speak. Due to the additive manufacturing, the planetary spindle 10 can be one-piece and closed on both sides, since the additional spindle 17 does not have to be mounted. This creates a larger volume in order to produce improved mixing. The gearing is retained.

• Diese Gestaltung ist prädestiniert für das adaptive Fertigungsverfahren, aber nicht auf Planetwalzenextruderbauteile beschränkt. Denkbar ist auch eine Kombination solch einer hohlen Form mit z.B. üblichen Geometrien an Extruderschnecken, wie beispielhaft bei Scher- und Mischteilen einzusetzen.

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

• This design is ideal for the adaptive manufacturing process, but is not limited to planetary roller extruder components. It is also conceivable to combine such a hollow shape with, for example, the usual geometries of extruder screws, for example in shearing and mixing parts.

List of reference symbols:

1

Extruders

2

First component of the extruder

3

Second component of the extruder

4

Filling funnel

5

drive

6

Extrusion direction

7

Planetary roller extruder

8th

Planetary roller cylinder

9

Central spindle

10

Planetary spindle

11

Gearing

12

Gearing A

13

Gearing B

14

Gearing C

15

Geometry of 10 that is no longer in engagement

16

Cavity in 10

17

Additional spindle

Claims (11)

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 in engagement with one another, characterized in that at least one of the components (2, 3) is designed with computer support, computer-aided manufacturing data prevail for this component (2, 3) and the component is additively manufactured on the basis of this manufacturing data, wherein the components manufactured in this way 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 of the medium. Extruder 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). Extruder to Claim 2 , characterized in that the contour changing over the length of the additively manufactured component (2, 3) comprises a modified toothing (11). Extruder 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. Extruder 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 in engagement with both the central spindle (9) and the planetary roller cylinder (8). Extruder to Claim 5 , characterized in that the planetary spindle (10) partially has no teeth and thus only comprises a general geometry. Extruder to Claim 5 , characterized in that the planetary spindle (10) is complex build and is completely or at least partially hollow. 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. Process for producing a component for an extruder according to Claim 1 , characterized in that the component (2, 3) is designed with computer support, computer-supported manufacturing data are generated therefrom, the component (2, 3) is additively manufactured on the basis of these manufacturing data, wherein the component manufactured in this way 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 of the medium. Component of an extruder according to Claim 1 , characterized in that the component (2, 3) is designed with computer support and thus computer-aided manufacturing data predominate and the component (2, 3) is additively manufactured on the basis of these manufacturing data. 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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