FR3073761A1 - IMPROVED TOOLS FOR ADDITIVE MANUFACTURE - Google Patents

Abstract

The invention relates to a tool (100) for the additive manufacturing of a part by powder deposition, the tooling comprising a powder ejection nozzle (10) having a first passage (26) to be traversed by the powder (2) to be deposited, and an ultrasound emitting device (40) associated with the nozzle (10) to vibrate and prevent clogging of the first passage (26).

Description

IMPROVED TOOLS FOR ADDITIVE MANUFACTURING DESCRIPTION

TECHNICAL AREA

The present invention relates to the field of additive manufacturing, and more particularly to the tools allowing the implementation of this manufacturing technique, also called 3D manufacturing.

It relates more specifically to the tools allowing a deposition of powder layer by layer, intended to be partly solidified using a laser beam.

STATE OF THE PRIOR ART

Conventional tools intended to implement such an additive manufacturing technique usually have an ejection nozzle, for example equipped with a passage of conical shape for ejecting the powder onto the powder layers previously deposited. More specifically, the nozzle allows the addition of powder directly into a liquid bath formed by a laser beam, which passes through a set of optical elements generally located within the nozzle.

Depending on the morphology and the particle size of the powder which passes through the nozzle, the dedicated passage within the nozzle is subject to a risk of total or partial clogging, in particular due to the formation of agglomerates of particles. In such a situation, the powder no longer flows from the nozzle, or only with a reduced flow rate compared to that expected, or even with a heterogeneous distribution of particle densities within the powder bundle. Consequently, the laser beam no longer interacts correctly with the powder, and it is reflected in the liquid bath until possibly weakening the laser source, which induces a risk for the user as well as for the tools. The manufacturing process must then be stopped, and the part discarded.

Furthermore, there are also cases in which particles are deposited in the passage of the nozzle, which can disturb the flow of carrier gas usually passing through this passage. The occasional lack of particles can be a source of porosity within the room. In addition, these particles trapped within the nozzle can subsequently detach under the effect of the carrier gas and / or the flow of powder, and then come to contaminate a part made of a different material.

STATEMENT OF THE INVENTION

To respond at least partially to the drawbacks identified above, the invention firstly relates to a tool for the additive manufacturing of a part by powder deposition, the tool comprising a powder ejection nozzle having a first passage intended to be crossed by the powder to be deposited, a second passage intended to be crossed by a laser beam, as well as an ultrasonic emitting device associated with the nozzle to make it vibrate.

The invention thus cleverly provides for coupling the ejection nozzle with an ultrasonic emitting device in order to vibrate this nozzle, and thus limit the risks of the formation of agglomerates of particles within the first passage. The risks of clogging are thus reduced, without drastically complicating the design of the tool. Indeed, the ultrasonic emitting device can be perfectly integrated into the design of the tool, and easily adapts to existing tools.

The invention thus makes it possible to extend the range of projectable materials, in particular in terms of particle size and powder morphology. It also guarantees better stability of the powder mass flow for long spraying times, thanks to the reduction of powder agglomerates in the nozzle.

Finally, since the vibrations generated by the ultrasonic emitting device also reduces the risks of particle deposition on the walls of the first passage of the nozzle, the risks of cross contamination are advantageously limited during the successive use of different materials.

The invention preferably provides at least any one of the following optional characteristics, taken individually or in combination.

The ultrasonic emitting device comprises a generator and a transducer supplied by the generator. Thus, conventionally, the transducer forms an excitation member which receives an electrical signal produced by the generator. The transducer then preferably constitutes the device member which is coupled to the powder ejection nozzle, to cause it to vibrate.

According to a first preferred embodiment, the transducer is fixed around the nozzle or integrated into it.

According to a second preferred embodiment, the tool comprises a system for cooling the nozzle, the system comprising at least one cooling channel running in the nozzle as well as a reservoir of cooling fluid supplying said channel. In addition, the transducer is associated with said reservoir to ultrasonically activate the cooling fluid which is in the reservoir, said transducer preferably being an ultrasonic emitting rod.

This solution has the advantage of reducing the size of the nozzle, by transmitting vibrations to it via the cooling fluid which passes through it.

Said ultrasonic emitting device is designed to deliver an ultrasonic signal at a frequency between 25 and 40 kHz, at a power of 750W.

The powder ejection nozzle also has a third passage intended to be traversed by a flow of gas protecting the powder.

The powder ejection nozzle is produced using several coaxial cones defining between them said first and second passages, and preferably also the third passage described above.

Finally, provision is made for the cooling channel to pass through the thickness of at least one of the cones forming the ejection nozzle.

The invention also relates to a method for producing an aircraft turbomachine part by additive manufacturing, said method comprising a powder deposition step carried out using a tool as described above.

Other advantages and characteristics of the invention will appear in the detailed non-limiting description below.

BRIEF DESCRIPTION OF THE DRAWINGS

This description will be made with reference to the accompanying drawings, among which;

- Figure 1 shows a front view schematically the implementation of a method of producing an aircraft turbomachine part by additive manufacturing;

- Figure 2 shows a schematic view of a tool according to a first preferred embodiment, for the implementation of the process shown schematically in the previous figure;

- Figure 2a shows a view similar to the previous one, showing an alternative embodiment;

- Figure 3 shows a view similar to that of Figure 2, according to a second preferred embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring first to Figure 1, there is shown schematically the implementation of a method for producing a part 1 of an aircraft turbomachine, by additive manufacturing.

It can be any part of a turbomachine produced for example from metallic and / or ceramic powder, such as a retention hook for a turbine casing.

The technique used is conventional, the method according to the invention being distinguished essentially from the prior techniques by the use of a tool specific to the invention, which will be described below.

The additive manufacturing targeted by the present invention implements a powder deposition. It is also called 3D manufacturing, and comes in different forms, for example called LMD (from the English "Laser Metal

Déposition "), LENS (from" Laser Engineered Net Shaping ", DMD (from English" Direct Métal Déposition), or CLAD ("Construction Laser Additive Directe").

This technology allows the construction of a part 1 by direct addition of powder 2 into a liquid bath 4, formed by a laser beam 6 on the surface of a substrate 8. The substrate 8 and the powder 2 can be two different materials or identical. The substrate can be a support which is then removed by machining, or a part to be repaired, or even a part on which an addition of function is carried out.

To manufacture the piece 1 progressively layer by layer, the tool 100 employed comprises a powder ejection nozzle 10 controlled by a device 12 for controlling and setting in motion the nozzle 10. The nozzle is shown only schematically in the figure 1. It allows the powder to be ejected, as well as the passage of the laser beam 6 in the direction of the liquid bath 4. The beam comes from a laser source 14 which is also part of the tool.

In practice, the manufacturing process includes a powder deposition step using the nozzle 10, the deposited powder being fused under the action of the laser beam 6, at the areas of the powder layer which must be solidified. to later form part 1.

FIG. 2 represents a first preferred embodiment of the ejection nozzle 10. Its design is based on the combination of several coaxial cones, here three cones nested one inside the other so as to define between them functional conical passages.

More specifically, it is an outer cone 20, a central cone 22, and an inner cone 24. Between the outer cone 20 and the central cone 22, there is defined a first conical passage 26 intended for be crossed by the powder to be deposited, the flow rate of which is regulated by the tool control device.

Furthermore, the central cone 22 internally defines a second passage 31 centered on the axis 30 of the nozzle, this axis also corresponding to the direction of the laser beam 6.

In addition, between the inner cone 24 and the central cone 22, there is defined a third conical passage 32 intended to be traversed by a flow of gas 34 protecting the powder. In fact, this gas flow 34 is interposed radially between the powder 2 and the laser beam 6, and thus allows the powder particles not to be melted before reaching the liquid bath at the level of the layers already deposited.

One of the features of the invention resides in the implementation of an ultrasonic emitting device 40 coupled to the nozzle, so as to cause it to vibrate and thus prevent clogging of the first passage 26 by agglomerates of powder, or else prevent particles from settling on the walls of this first passage 26.

The ultrasound emitting device 40 comprises a generator 42 and a transducer 44. The generator 42 transmits an electrical signal to the transducer 44, via appropriate wiring 48. The transducer is then placed in contact with the outer cone 20 of the nozzle, for example at an upper shoulder 50. The mechanical retention of the transducer is effected by means of a clamp 46 disposed around the shoulder 50, and preferably centered on the axis 30. According to an alternative , the transducer 44 is integrated into the nozzle, preferably in a housing 52 of the shoulder 50, as has been shown diagrammatically in FIG. 2a.

It is noted that in this first preferred embodiment, the transducer 44 could be in contact with another part of the outer cone 20, or even in contact with one of the other two cones 22, 24, without departing from the scope of the invention.

A second embodiment is shown in FIG. 3. In this mode, the ultrasound is not directly transmitted by the transducer 44 to the external cone 20, but transmitted to a coolant 56.

The tool 100 in fact comprises a system 55 for cooling the nozzle, which comprises a cooling channel 58 running through the outer cone 20 of the nozzle, in the thickness of the latter. The channel 58 extends for example in helical form all along this cone, being supplied by a liquid reservoir 60 with which it communicates. A pump makes it possible to supply this power, while a heat exchanger is also provided for cooling the heated fluid leaving the cone 20 and joining the reservoir 60. The exchanger (not shown) could moreover be arranged at this tank.

The transducer 44 is coupled to the tank 60 to ultrasonically activate the cooling fluid 56 which is in this tank. This transducer can be fixed to the wall of the reservoir 60, or else immersed in a sealed manner in the liquid located within this reservoir. It preferably takes the form of a rod emitting ultrasound.

In this second embodiment, the nozzle has a reduced bulk, while being subjected to vibrations transported by the coolant 56 which circulates in the channel 58.

Here again, it is indicated that the cooling channel 58 could be provided alternately or simultaneously on the other two cones 22, 24, without departing from the scope of the invention.

Finally, for optimal vibration generation, the emitting device 40 is preferably designed to deliver an ultrasound signal at a frequency between 25 and 40 kHz, at a power of 750W.

Of course, various modifications can be made by those skilled in the art to the invention which has just been described, only by way of nonlimiting examples.

Claims (9)

1. Tool (100) for the additive manufacturing of a part (1) by powder deposition, the tool comprising a nozzle (10) for ejecting powder having a first passage (26) intended to be traversed by the powder (2) to be deposited, as well as a second passage (31) intended to be crossed by a laser beam (6), characterized in that the tool also includes an ultrasonic emitting device (40) associated with the nozzle ( 10) to make it vibrate. 2. Tool according to claim 1, characterized in that the ultrasonic emitting device (40) comprises a generator (42) and a transducer (44) supplied by the generator. 3. Tool according to claim 2, characterized in that the transducer (44) is fixed around the nozzle (10) or integrated therein. 4. Tool according to claim 2, characterized in that it comprises a system (55) for cooling the nozzle, the system comprising at least one cooling channel (58) passing through the nozzle as well as a fluid reservoir for cooling (60) supplying said channel, and in that the transducer (44) is associated with said reservoir (60) to ultrasonically activate the cooling fluid (58) which is in the reservoir, said transducer (44) being preferably a ultrasonic bar. 5. Tool according to any one of the preceding claims, characterized in that said ultrasonic emitting device (40) is designed to deliver an ultrasonic signal at a frequency between 25 and 40 kHz, at a power of 750W. 6. Tool according to any one of the preceding claims, characterized in that the powder ejection nozzle (10) also has a third passage (32) intended to be traversed by a stream (34) of powder protective gas . 7. Tool according to any one of the preceding claims, characterized in that the powder ejection nozzle (10) is produced using several coaxial cones (20, 22, 24) defining between them at least said first and second passages (26, 31). 8. Tool according to the preceding claim combined with claim 4, characterized in that the cooling channel (58) travels in the thickness of at least one of the cones (20, 22, 24) forming the nozzle ejection (10). 9. Method for producing a part (1) of an aircraft turbomachine by additive manufacturing, said method comprising a powder deposition step (2) carried out using a tool (100) according to any one of the preceding claims.