METHOD FOR MANUFACTURING A PART

Abstract

A method for manufacturing a part layer-upon-layer using Additive Manufacturing technology suitable for structural applications. The method includes selectively depositing at least a first type filament and a second type filament, wherein the second type filament differs from the first type filament at least in the cross-sectional dimension.

Claims

1. A method for manufacturing a part layer-upon-layer using an additive manufacturing technology, wherein the method comprises: depositing a first type of filament, wherein at least a first portion of the first type of filament is deposited adjacent a second portion of the first type of filament such that a channel is formed between the first and second portions, and depositing at least a portion of a second type filament in or along the channel; wherein the second type of filament differs in least a cross-sectional dimension from the first type of filament.

2. The method for manufacturing according to claim 1, wherein the first type of filament is larger in cross section than the second type filament.

3. The method for manufacturing according to claim 1, wherein at least one of the first type filament and the second type filament has shape in cross section that is a circular, triangular or ellipsoidal.

4. The method for manufacturing according to claim 1, wherein at least one of the first type of filament and the second type of filament is a fibrous material reinforcement embedded within a meltable material or thermoplastic material.

5. The method for manufacturing according to claim 1, wherein the second type of filament is deposited as pellets or spheres.

6. The method for manufacturing according to claim 1, wherein the second type of fibrous material is formed of fibrils, nanofibers, carbon fillers and short fibers.

7. The method for manufacturing according to claim 1, wherein the first type filament has a fiber volume content of at least 50%, and the second type filament has a fiber volume content below 50%.

8. The method for manufacturing according to claim 1, wherein at least a portion of the second type filament is deposited alongside the first portion of the first type filament, and the channel is formed depositing the second portion of the first type of filament after the second type of filament is deposited.

9. The method for manufacturing according to claim 1, wherein a cross-sectional dimension and/or length of the second type filament is sufficient to infill the channel.

10. The method for manufacturing according to claim 1, wherein the first type filament is deposited at a first temperature while the second type filament is deposited at a second temperature different from the first temperature.

11. The method for manufacturing according to claim 10, wherein the method further comprises cooling the part at a predefined cooling rate.

12. The method of claim 11, wherein the predefined cooling rate achieves a degree of crystallization of at least 32% in the part.

13. The method for manufacturing according to claim 1, wherein a portion of the part is manufactured by repeatedly alternating the performance of the forming and the depositing steps.

14. The method for manufacturing according to claim 1, further comprising depositing at least a portion of the second type filament along the channel formed by the first type filaments to form part of an outer wall of the part.

15. The method for manufacturing according to claim 14, wherein the outer wall of the part is formed entirely by at least one layer of the second type filament.

16. A method to form a party by additive manufacturing comprising: depositing a first type of filament by additive manufacturing to form a first layer, wherein a channel is formed between a first portion of the first type of filament and a second portion of the first type of filament which is adjacent the first portion; and at least partially filling the channel by depositing a second type of filament, wherein the second type of filament has a cross-sectional dimension which is smaller by at least a factor of two to a corresponding cross-sectional dimension of the first type of filament.

17. The method of claim 16, wherein the second type of filament is deposited parallel to the first type of filament.

18. The method of claim 16, wherein the second type of filament is deposited after the deposition of the first portion of the first filament and before the deposition of the second portion of the first type of filament.

19. The method of claim 16, wherein the first portion of the first type of filament is in a layer different than a layer of the second portion of the first type of filament.

20. The method of claim 19, wherein the second type of filament is deposited along a direction offset from a direction of the layers of the first type of filaments.

Description

DESCRIPTION OF THE DRAWINGS

[0078] These and other characteristics and advantages of the invention will become clearly understood in view of the detailed description of the invention which becomes apparent from an embodiment(s) of the invention, given just as an example and not being limited thereto, with reference to the drawings.

[0079] FIG. 1 shows layers made by first type filaments deposited alongside each other with process-induced triangular voids.

[0080] FIG. 2 shows layers made by first type filaments deposited alongside each other with process-induced kite-shaped voids.

[0081] FIGS. 3a and 3b show a cross-sectional view of (FIG. 3a) two layers each formed by depositing first and second type filaments, and (FIG. 3b) shows the same layers as in FIG. 3a but with the second type filaments being deposited as a melted, e.g., liquid, filament that filling the channels and thereby avoids the formation of voids.

[0082] FIG. 4 shows layers made by first and second type filaments wherein the second type of filaments are deposited in an offset external dimension as compared to the first type of filaments.

DETAILED DESCRIPTION

[0083] The person skilled in the art should recognize that aspects described herein can be embodied either as a method for manufacturing a part, or as the part itself.

[0084] A method for manufacturing a part layer-upon-layer using Additive Manufacturing technology has been invented and disclosed herein. The method includes performing at least once the steps of: (a) forming a layer by depositing first type filaments, at least a portion of the first type filaments (1) being deposited alongside each other thus creating at least one channel (3), and (b) depositing at least a portion of a second type filament (2) along, e.g., in, said channel (3), wherein the second type filament (2) differs from the first type filament (1) at least in the cross-sectional dimension.

[0085] The method may use an additive manufacturing tool comprising a printing chamber housing a build sheet and at least one print head configured to move over the build sheet and to deposit selectively the first type of filament(s) (1) and the second type of filament(s) (2).

[0086] The print head may be equipped with different nozzles interchangeable during the printing process or a single nozzle with variable geometry and/or dimension. As mentioned, the print head(s) may also comprise a heater block for heating the meltable filaments (1, 2) to temperature, such as to melt the filament prior to be deposited to form a part.

[0087] The print tool may further comprise spool(s) for storing the filaments (1, 2).

[0088] In an embodiment, the print head is configured to be moved over the build sheet in the three-translational axes (X, Y, Z) and/or rotations (around X, Y, Z) for printing more complex geometries. Optionally, the print head(s) may be limited to move over the build sheet just in horizontal directions (X, Y) while the movement in vertical Z-direction is performed by the build sheet, thus implementing 2.5D fabrication. These movements may be performed by actuators and/or servos, one for each direction and/or rotations.

[0089] FIG. 1 depicts layers made by first type filaments (1) deposited alongside each other and having created triangular voids (3.1). This process-induced triangular voids (3.1) occurs when a single first type filament (1) is deposited over a channel (3) created by two filaments (1) of the same type deposited alongside each other.

[0090] A channel (3) is created when two filaments (1) of the same type, e.g., first type, are deposited alongside each other, while the process-induced void (3.1) requires further filament(s) (1) to be disposed above them, i.e. a closed perimeter. Thus, the channel (3) becomes a void (3.1) when a layer of filaments is deposited over the side-by-side portions of the first type of filaments in the lower layer shown in FIG. 1. The formation of voids can be avoided using the method disclosed herein.

[0091] FIG. 2 depicts layers made by first type filaments (1) deposited alongside each other and having created kite-shaped voids (3.2).

[0092] Kite-shaped, e.g., rhombus, voids (3.2) occur when portions of first type filaments (1) are deposited over a channel (3) created by filaments (1) of the same type in a previously deposited layer.

[0093] FIGS. 1 and 2 depict the deposited first type filaments (1) flattened due to gravitational and temperature-related mechanisms that take place during cooling and hardening.

[0094] FIG. 3a depicts a cross-sectional view of a hypothetical situation where layers made by first type filaments (1) are alternated with layers made of second type filaments (2) but without having being fused yet.

[0095] It can be observed that, in this example, both the first type filaments (1) and the second type filaments (2) have a circular cross-sectional shape. Nevertheless other cross-sectional shapes can be selected or combined to maximize infill.

[0096] As visible in FIG. 3a, a second type filament (2) has been deposited along a channel (3) formed by a pair of first type filaments (1) deposited alongside each other underneath. Additionally, two second type filaments are shown, which have been deposited on two respective first type filaments, along them, so as to infill a channel to be created by a subsequent pair of first type filaments deposited over it alongside each other.

[0097] The first type filaments (1) may have a greater cross-sectional dimension than the second type filaments (2), such that the cross-sectional dimension, e.g., diameter, of the first type of filament is several times, e.g., twice, triple, five times or ten times, the cross-sectional dimension, e.g., diameter, of the second type of filament. The cross-sectional dimension of the second type filaments by be chosen to infill the channel and fill any voids (3.1, 3.2) that would have been formed but for the second type of filament. The cross-sectional dimension of the second type of filament may be selected to infill the channel and void, wherein the selection accounts for thermal expansion and/or shrinkage of the first and second type of filaments (1, 2) during the fusing and hardening of the filaments.

[0098] FIG. 3b shows the second type filaments (2) infill what would have been voids between two layers of the first type of filaments.

[0099] A third or further types filaments may be selectively deposited together with the first type filament and the second type filament to achieve the desired infilling of channels and voids.

[0100] FIG. 4 depicts a first layer of a first type filaments (1) which will be adjacent a second layer also of the first type of filaments. Between the two layers is a second type filaments (2) which fills a channel between the two layers of the first type of filament. The layers of the first type of filaments are oriented in a first direction/plane perpendicular to a second direction of the second type of filaments. Thus, the layers made by the second type filaments (2) are oriented to be offset the external dimensions of the layers formed by the first type of filaments.

[0101] The channel formed by layers of the first type of filaments may be at an outer surface of a part. The channel is infilled by depositing the second type of filaments along a direction at an angle to, e.g., perpendicular, to the direction of the first type of filaments. The outer surface, e.g., outer wall, is formed by the first and second types of filaments.

[0102] The second type filaments (2) may be oriented in a second direction to facilitate the printing process and to be used as support material for the layer(s) formed by the first type of filaments. Layers of first type filaments (1) may be oriented according to directions of expected loads applied to the part to achieve good structural properties of the part. The layer(s) of the second type filaments (2) may be deposited along directions which allow the second type of filaments to fill channels and need not be along directions to provide structural support for the part. As a result, the strength requirements of a part can be satisfied by the first type of filaments and the dimensional tolerances of the part can be satisfied with both the first and second types of filaments.

[0103] In addition, the method may comprise a step of depositing at least a portion of a second type filament (2) along channels (3) formed by first type filaments (1) forming part of an outer wall of the part. Thus, the second type of filament (2) forms part of the outer wall with the first type of filament (1). This embodiment may be of application, for instance, for producing a local roving or fill and thus create any required area to get the final shape of the part allowing the production of more complex shapes.

[0104] In aeronautical parts, especially for ‘T-profile’ composite parts such as stringers, a roving is a composite filler adapted to fill the space between both feet (i.e. the diverting point of both halves of the ‘T-profile’ composite part). Therefore, a ‘roving’ will be understood as a bundle of second type filaments which may be unidirectional and unspun or otherwise shaped into patterns to provide structural continuity and void avoidance.

[0105] Furthermore, if the outer wall of the part is made entirely by layer(s) of second type filaments (2), not only dimensional tolerances are improved but the resulting tightness prevents water ingestion and de-bonding.

[0106] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.