DE102017119364A1 - Method and device for layered application of a plastic melt - Google Patents

Abstract

Device (1) for the layered application of a plastic melt (2), comprising at least one nozzle (3) which is arranged on at least one inlet (4) for the plastic melt (2) and for the plastic melt (2) can be flowed through, wherein the at least a nozzle (3) has at least one outlet (5) with an outlet width (6) which is adjustable in a multistage or continuous manner between at least one adjusting device (7) of the nozzle (3) between a minimum and a maximum. Furthermore, methods for the production of thermoplastic components are specified with such a device.

Description

The invention relates to a device and a method for the layered application of a plastic melt, in particular for producing a thermoplastic component.

In various technical areas, additive manufacturing processes for the manufacture of predefined components have meanwhile taken hold. Here, in particular, the 3D printing is highlighted. The alternative manufacturing methods include a process whereby the design data for the part is given digitally in the form of 3D design data. An apparatus then builds the component in layers according to this 3D design data by depositing material. Depending on the field of application, different starting materials for the layer structure can be selected here, for example also metals and / or plastics and / or composite materials.

Obviously, such a layered construction of a component takes time. Further, it should be noted that increasing the build speed of the layers may result in a deterioration in detail imaging capability. This means, for example, that with increasing build speed, the dimensional accuracy or shape tolerances for the component to be produced can no longer be met. In addition, it should be noted that the tools required for the layer structure must be moved regularly, so that here also inertias, vibration or the like can lead to a deterioration of the dimensional accuracy.

To achieve a better surface quality and / or increased component quality, thin layer thicknesses would be desirable. However, when using low layer thicknesses inevitably increases the production time.

The reduction of production time with consistent quality can therefore be regarded as a central challenge of additive manufacturing processes. This is especially true in the field of plastic-based additive manufacturing processes.

On this basis, it is an object of the present invention, at least partially solve the problems explained with reference to the prior art. In particular, it should be achieved that in such additive manufacturing process, the body speed and component quality can be better coordinated. In addition, a variable use of such additive manufacturing processes is to be achieved, in particular in the case of plastic-based additive manufacturing processes.

These objects are achieved with the features of claim 1. Advantageous embodiments, in particular parent assemblies or operating methods, result from the dependent claims. It should be noted that the features listed individually in claims in any technologically meaningful manner can be combined with each other and specify other embodiments of the invention. The description, in particular also in connection with the figures, explains these technical features and other embodiments of the invention.

To this end, a device contributes to the layered application of a plastic melt, as described below. The device comprises at least one nozzle, which is arranged on at least one inlet for the plastic melt and can be flowed through for the plastic melt. The at least one nozzle has at least one outlet with an outlet width which can be adjusted in a multistage or continuous manner between at least one adjusting device of the nozzle between a minimum and a maximum.

The device mentioned here may, for example, be a print head of a 3D printer. The device may include one or more nozzles. Each of the nozzles can be equipped with at least one inlet for a plastic melt. Usually one feed per nozzle will be sufficient. The optionally in the nozzle or previously heated plastic melt can flow through the nozzle at predetermined times. For this purpose, the nozzle has at least one, possibly centrally arranged, outlet. Through the outlet, the plastic melt can flow out of the nozzle, forming a kind of (partially) continuous strand and, for example, then laid down in layers. The outlet has an outlet width. The outlet width characterizes the (largest) extension of the outlet (transverse to the flow direction of the plastic melt), which can be traversed by the plastic melt. If the outlet has, for example, a cylindrical shape, the outlet width can be equated with the diameter. If the outlet has an angular or polygonal cross-sectional shape, the maximum distance between opposite points of this cross-section can be considered below the outlet width.

Next, the nozzle now has at least one adjusting device, which can adjust the outlet of the outlet. It is possible that each nozzle is associated with a single adjustment device. It is further possible that, as far as a plurality of nozzles are provided, an adjusting device for several or all nozzles is provided. The adjusting device can be arranged on the nozzle and / or integrated in the nozzle. The adjusting device is in particular associated with a specific nozzle or a specific number of nozzles. The adjusting device can be designed as a separate unit, which is positioned in and / or at an orifice of the outlet. The adjusting device is set up so that it can influence the outlet in such a way that the outlet width is variable. The adjusting device can vary the outlet width in such a way that, starting from a minimum value, it is variable to a maximum value and then back again in a multistage or continuous manner. The maximum of the outlet width can be several times greater than the minimum, z. B. by at least a factor of 2.0 or even at least a factor of 3.5. The minimum value of the outlet width may be, for example, 0 millimeters (fully closed) or z. B. to a maximum of 1.0 millimeters. The maximum value of the outlet width can be for example at least 1.2 millimeters, 2.5 millimeters or 4 millimeters.

"Multi-stage" in this context means that the outlet width is adjustable to a plurality of intermediate values between the minimum value and the maximum value. The number of intermediate values is preferably greater than 5 or 10. In this context, "continuous" means that the adjusting device can set the outlet width to essentially any value between minimum and maximum, in particular if this results in application-specific differences with regard to the outflow behavior of the plastic melt and / or the mechanics to control the adjustment revealed. The adjusting device can act on the outlet width in such a way that it is influenced from the outside and / or from the inside. For example, an inner and / or an outer region of the outlet can be partially closed or extended.

The adjusting device may comprise one or more movable and / or (elastically) deformable adjusting elements, which act on the outlet or the current outlet width. Movable adjusting elements may be flaps, tabs, conical sleeves or rings or the like, which are at least partially movable for adjusting the outlet width. An (elastically) deformable adjusting element can be provided in the manner of an elastic sleeve, an annular disc or the like, which can be compressed and / or widened.

The at least one adjusting device may comprise a diaphragm arrangement, with which the outlet of the nozzle is partially coverable. It is preferred that the diaphragm arrangement comprises a plurality of mutually coordinated movable blades.

The diaphragm arrangement is in particular designed such that it covers (only), starting from the outer circumference of the outlet peripheral regions. The diaphragm arrangement is in particular designed or set up so that it can not completely close the outlet. The diaphragm arrangement is arranged in particular in the region of the mouth of the nozzle.

The diaphragm arrangement may have a drive unit, with which a plurality of fins, which may be mounted in the peripheral region of the nozzle, are pivoted simultaneously or in a coordinated manner. In each case, radially inwardly oriented sections of the lamellae each partially form an aperture which is smaller than the cross section of the outlet, as a result of which the overall outlet width can be reduced.

It is preferable that the outlet has a polygonal cross section. Such a polygonal cross-section of the outlet means that the edges on the component to be produced can be sharper and more accurate. This results in particular a greater flexibility and detail accuracy. It is preferred that the cross-section is at least hexagonal or even at least dodecagonal.

• - mindestens ein Reservoir für eine Kunststoffschmelze, das mit einem Zulauf einer Düse einer Vorrichtung der hier vorgeschlagenen Bauart verbunden ist,
• - eine Fördereinheit zur Förderung der Kunststoffschmelze hin zu der Düse,
• - einen Bewegungsapparat zum räumlichen Verfahren der mindestens einen Düse, eine Steuereinheit, eingerichtet zum abgestimmten Betrieb der Fördereinheit der mindestens einen Verstelleinrichtung und des Bewegungsapparats.

Furthermore, an arrangement for producing a thermoplastic component is proposed, which comprises at least the following:

• at least one reservoir for a plastic melt, which is connected to an inlet of a nozzle of a device of the type proposed here,
• a conveyor unit for conveying the plastic melt towards the nozzle,
• a musculoskeletal system for spatially moving the at least one nozzle, a control unit, arranged for the coordinated operation of the conveying unit of the at least one adjusting device and the musculoskeletal system.

The arrangement proposed here can be designed, for example, in the manner of a 3D printer for industrial applications. The reservoir can be designed in the manner of a tank, container or the like. The reservoir, the inlet and / or the nozzle may be associated with a heater, so that optionally a storage of plastic granules is possible and melted by a heating device, the plastic granules and in a flowable state is transferred. The reservoir may comprise the storage container for the plastic and the supply lines up to the nozzle.

The conveying unit for conveying the plastic melt can be designed, for example, in the manner of a screw extruder, a feed pump or the like. Valves may also be included here which realize a temporally and / or spatially predefined flow path for the plastic melt towards the one or more nozzles.

The musculoskeletal system can be set up such that it can spatially displace the nozzle and / or still adjacent components, in particular also the adjusting device. Here, the musculoskeletal system is at least arranged so that it realizes predefined traversing paths in a spatial plane, so that, for example, drive components are available that allow movement in a vertical coordinate system. It is also possible that the musculoskeletal system additionally detects a third dimension. The relative movement of the nozzle perpendicular to a base on which the thermoplastic component is to be created, allows the positioning of the plastic melt in a layer. In addition, the musculoskeletal system can still set a delivery relative to the pad, so that each delivery begins a new shift.

Furthermore, the control unit is provided, which is set up in particular for receiving, storing and / or processing 3D design data for the production of the component. The control unit is data-conducting so connected to the conveyor unit, the adjustment and the musculoskeletal system that this allows a coordinated operation. Thus, for example, the movement speed which is set with the musculoskeletal system can be adjusted by the control unit to a setting of the adjusting device which is suitable for this purpose and thus to the outlet width of the nozzle. In addition or as an alternative to one of the two operational specifications, the inflow of plastic melt towards the nozzle can also be adapted at specific times.

The arrangement can then be supplemented by a number of other components, such as sensors (push button, cameras, etc.), a nozzle changing station, a thermal treatment unit, etc., where these additional components may also be associated with the control unit data leading and the coordinated operation of the conveyor unit, the at least one adjusting and / or the musculoskeletal system are tuned thereto.

1. a. Bereitstellen einer Kunststoffschmelze,
2. b. Bereitstellen eines Schichtmodells des Bauteils,
3. c. Erzeugen mehrerer zumindest teilweise aufeinander aufbauender Schichten der Kunststoffschmelze auf einer Unterlage, wobei die Schichten zumindest teilweise mit verschiedener Auslassweite der Düse erzeugt werden,
4. d. Verfestigen der Kunststoffschmelze.

In particular, a method for producing a thermoplastic component is also proposed, wherein the arrangement described here is used. The method comprises at least the following steps:

1. a. Providing a plastic melt,
2. b. Providing a layered model of the component,
3. c. Producing a plurality of at least partially mutually constituent layers of the plastic melt on a base, wherein the layers are generated at least partially with different outlet width of the nozzle,
4. d. Solidifying the plastic melt.

It should first be noted that the numbering of the method steps does not necessarily dictate an order of the individual method steps. Rather, it is possible that the steps can be performed at least partially in parallel or temporally overlapping or in a different order. This applies in particular to the case where these method steps are repeated several times (individually and / or in combination with one another).

Step a. may include, in particular, that the plastic melt is produced from a plastic granules. For this purpose, a plastic granulate may optionally be mixed with additives. In addition to a mixing process, a heating process may additionally be used beforehand and / or afterwards, so that the plastic is present in the form of a melt, that is, capable of flowing. This can be done in the arrangement proposed here or externally.

The layer model of the component can be supplied in particular as a data record in electronic form of the arrangement, namely in particular the control unit.

The layer model, which in particular comprises the 3D design data, can be stored in the control unit.

Based on this layer model, step c. generates a component, wherein a plurality of at least partially mutually constituent layers of the plastic melt are produced on a substrate. This particularly addresses an adaptive production method, in particular so-called 3D printing. Usually, such a component, depending on the complexity, constructed with a plurality of layers. Insofar as undercuts, protrusions or the like are required, the layers can project beyond each other, wherein usually the layers are always supported against one another. According to step c. is provided that individual layers complete and / or individual layers are at least partially generated so that while a different outlet width of the nozzle is set. In other words, this means that during the production of a layer or between the generation of several layers, the adjustment of the nozzle is activated, and thus the outlet of the nozzle at least once, preferably several times, is adjusted between the minimum and the maximum. This can be recognized directly on the layers produced, because there is a respective changed shape of the plastic melt strand is recognizable.

So that the thermoplastic component finally obtains its structural integrity or stability, solidification of the plastic melt takes place. This can be done for example via a curing process at room temperature or use of additives, but it is also a thermal treatment possible.

The production of a thermoplastic component can be carried out in particular by means of an FDM process or an FFF process. "FDM" stands for "Fused Deposition Modeling". This plastic is heated until it reaches an almost liquid state of aggregation and thus can be pressed through a nozzle. The resulting, possibly extremely fine thread then serves to produce the individual layers. "FFF" stands for "fused filament fabrication" in which molten plastic is also built up layer by layer into a component. The raw materials used here are, for example, ABS filaments (ABS: acrylonitrile-butadiene-styrene) or PLA filaments (PLA: polylactate), which are wound on spindles (filaments). These filaments are brought into contact with a hot nozzle so that they can be melted and applied in layers.

The plastic used is in particular at least one of the following thermoplastics: acrylonitrile-butadiene-styrene (ABS), polyamides (PA), polylatate (PLA), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene (PE) , Polypropylene (PP), polystyrene (PS), polyetheretherketone (PEEK) and polyvinyl chloride (PVC).

In this respect, the use of the device described here for the layered application of a plastic melt for the production of a thermoplastic component is preferred. Such a use is particularly suitable when the production of the thermoplastic component takes place by means of an FDM process or an FFF process.

With the invention proposed here it is possible to produce layer thicknesses of different thicknesses. The nozzle proposed for this purpose is used in particular in the FDM or FFF process for vector-based layer-by-layer application of plastic melt for the production of thermoplastic components. The structure of the nozzle is in particular such that varies by a diaphragm system, the diameter variation for the effluent plastic melt and thus a different layer thickness can be generated. The combination of different layer thicknesses with a skin core strategy increases the build-up rate of the process while maintaining the same quality.

• 1: eine schematische Darstellung einer Anordnung zur Herstellung eines thermoplastischen Bauteils,
• 2: eine Düse mit Verstelleinrichtung mit eingestellter maximaler Auslassweite,
• 3: eine Düse mit Verstelleinrichtung bei eingestellter minimaler Auslassweite, und
• 4: eine Draufsicht auf eine Ausgestaltungsvariante einer Verstelleinrichtung.

The present invention and the technical environment will be explained in more detail with reference to FIGS. It should be noted that the figures are schematic in nature and are not intended to limit the scope of the invention. As far as a number of technical features are shown in combination in a figure, the technical features can be extracted individually and combined with other technical features of the description or other figures, as far as this is not explicitly excluded. Show it:

• 1 FIG. 2: a schematic representation of an arrangement for producing a thermoplastic component, FIG.
• 2 a nozzle with adjusting device with set maximum outlet width,
• 3 : a nozzle with adjusting device with the minimum outlet width set, and
• 4 : A plan view of a design variant of an adjustment.

1 shows very schematically an arrangement 11 for producing a thermoplastic component. The component is here in particular by successive layers 16 generated, which on a pad 17 be filed.

For this deposition process, the device has a nozzle 3 on, the at least one inlet 4 for a plastic melt 2 is arranged and so even for the plastic melt 2 can be flowed through.

The arrangement 11 or nozzle 3 is a reservoir 12 assigned, from the plastic or plastic melt 2 towards the inlet 4 the nozzle can be supplied. This can be done in particular by using a conveyor unit 13 be accomplished to promote the plastic melt or the plastic.

So that the nozzle 3 different areas of the underlay 17 and thus the formation of even layers 16 can produce, is the nozzle 3 movable. The planar or spatial movement can be via a musculoskeletal system 14 will be realized. Regarding relative movement of nozzle 3 and documents 17 It should be noted that this is the nozzle 3 and / or the documents 17 (up / down, left / right, front / back) can be moved.

The order 11 also includes a device 1 , which next to the nozzle 3 at least one adjusting device 7 includes, with the outlet 6 the outlet 5 the nozzle 3 between a maximum and a minimum multistage or continuously adjustable. For this purpose, the adjusting 7 for example, in the manner of a diaphragm arrangement 8th be executed, which has an associated drive unit 19 can be adjusted.

Next is still a control unit 15 provided, via data lines 18 with the conveyor unit 13 , the adjusting device 7 and the musculoskeletal system 14 is connected, and is set up so that these have a coordinated operation of conveyor unit 13 , Adjusting device 7 and musculoskeletal system 14 guaranteed.

2 shows an embodiment of a nozzle 3 with an outlet 5 , Front side near the mouth of the nozzle 3 is an adjusting device 7 arranged, which has an outlet 6 Are defined. In 2 a state is shown in which the adjusting device has a maximum value of the outlet width 6 has set.

3 again shows the variant of a nozzle 3 to 2 , in which case the adjusting device 7 the nozzle 3 is set up so that these have a minimum value of the outlet width 6 the outlet 5 Are defined.

4 shows an embodiment of an adjustment device in the manner of a diaphragm arrangement 8th , It can be seen that the aperture arrangement 8th a variety of swiveling blades 9 includes, in the central area each partially a cross section 10 the outlet and thus the Auslassweite 6 define. The cross section is polygonal. In addition, a drive unit 19 formed, with the same time and in a coordinated manner, the slats 9 are pivotable, so hereby multi-stage or continuous the outlet 6 is adjustable.

LIST OF REFERENCE NUMBERS

1

contraption

2

Plastic melt

3

jet

4

Intake

5

outlet

6

Auslassweite

7

adjustment

8th

diaphragm arrangement

9

lamella

10

cross-section

11

arrangement

12

reservoir

13

delivery unit

14

musculoskeletal

15

control unit

16

layer

17

document

18

data line

19

drive unit

Claims (8)

Device (1) for the layered application of a plastic melt (2), comprising at least one nozzle (3) which is arranged on at least one inlet (4) for the plastic melt (2) and for the plastic melt (2) can be flowed through, wherein the at least a nozzle (3) has at least one outlet (5) with an outlet width (6) which is adjustable in a multistage or continuous manner between at least one adjusting device (7) of the nozzle (3) between a minimum and a maximum. Device (1) according to Claim 1 in which at least one adjusting device (7) comprises a diaphragm arrangement (8) with which the outlet (5) of the nozzle (3) can be partially covered. Device (1) according to Claim 2 in which the diaphragm arrangement (8) comprises a plurality of mutually coordinated movable blades (9). Device (1) according to one of the preceding claims, in which the outlet (5) has a polygonal cross-section (10). Arrangement (11) for producing a thermoplastic component, comprising a reservoir (12) for a plastic melt (2), which is connected to an inlet (4) of a nozzle (3) of a device (1) according to one of the preceding claims, a conveyor unit (13) for conveying the plastic melt (2) towards the nozzle (3), a movement apparatus (14) for spatially moving the at least one nozzle (3), and a control unit (15) arranged for the coordinated operation of the Delivery unit (13), the at least one adjusting device (7) and the musculoskeletal system (14). A method for producing a thermoplastic component with an arrangement (11) according to Claim 5 comprising at least the following steps: a. Providing a plastic melt (2), b. Providing a layered model of the component, c. Producing a plurality of at least partially mutually constituent layers (16) of the plastic melt (2) on a base (17), wherein the layers (16) are at least partially produced with different outlet width (6) of the nozzle (3), d. Solidifying the plastic melt (2). Use of a device (1) according to one of the preceding Claims 1 to 4 for producing a thermoplastic component. Use after Claim 7 wherein the production of the thermoplastic component takes place by means of an FDM process or an FFF process.

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