US-12617147-B2 - Method for the additive manufacture of an object from a powder layer

US12617147B2US 12617147 B2US12617147 B2US 12617147B2US-12617147-B2

Abstract

A method for the additive manufacturing of an object from a powder layer comprises the steps of: projecting ( 200 ) a beam of energy onto a surface of the layer of powder in the form of a spot so as to melt the powder, scanning ( 202 ) the surface with the beam of energy so that the spot travels over the surface in a movement made up of a translation in a longitudinal direction of scanning and of a wobbling movement having at least a component in a direction of wobble, and adjusting ( 204 ) the focus of the beam of energy during the scanning according to the translation in the longitudinal direction of scanning but without taking account of the component of the wobbling movement in the direction of wobble.

Inventors

Franck Denavit
Etienne Blanchet

Assignees

ADDUP

Dates

Publication Date: 20260505
Application Date: 20210511
Priority Date: 20200512

Claims (10)

1 . A method of additive manufacturing of an object from a layer of powder, the method comprising: projecting a beam of energy onto a surface of the layer of powder in the form of a spot so as to melt the powder; scanning the surface with the beam of energy so that the spot travels over the surface in a movement consisting of a translation in a longitudinal scanning direction and of a wobbling movement having at least one component in a wobbling direction; and adjusting a focus of the beam of energy during the scanning based on the translation in the longitudinal scanning direction but without taking account of the at least one component in the wobbling direction.
2 . The method according to claim 1 , wherein the wobbling movement comprises a transverse component in a transverse scanning direction perpendicular to the longitudinal scanning direction, and wherein the focus of the beam of energy is adjusted without taking account of the transverse component.
3 . The method according to claim 2 , wherein the transverse component of the wobbling movement oscillates at a frequency of at least 1 kHz.
4 . The method according to claim 2 , wherein the transverse component of the wobbling movement oscillates at an amplitude of between 100 micrometers and 2 millimeters.
5 . The method according to claim 1 , wherein the wobbling movement comprises a longitudinal component in the longitudinal scanning direction, and wherein the focus of the beam of energy is adjusted without taking account of the longitudinal component.
6 . The method according to claim 5 , wherein the wobbling movement comprises a transverse component in a transverse scanning direction perpendicular to the longitudinal scanning direction, and wherein the transverse component of the wobbling movement oscillates at a frequency of at least 1 kHz.
7 . The method according to claim 5 , wherein the longitudinal component of the wobbling movement oscillates at an amplitude of between 100 micrometers and 2 millimeters.
8 . The method according to claim 1 , wherein the spot travels a path comprising a succession of loops offset from one another in the longitudinal scanning direction.
9 . The method according to claim 1 , wherein the focus of the beam is adjusted using precalculated focusing parameter values calculated prior to the projecting of the beam of energy, each precalculated focusing parameter value being associated with a position of the spot on the surface.
10 . A device for additive manufacturing of an object from a layer of powder, the device comprising an energy source configured to project a beam of energy onto a surface of the layer of powder in the form of a spot so as to melt the powder, the energy source comprising a control unit configured to: cause the beam of energy to scan the surface so that the spot travels over the surface in a movement consisting of a translation in a longitudinal scanning direction and of a wobbling movement having at least one component in a wobbling direction; and adjust a focus of the beam of energy during the scanning based on the translation in the longitudinal scanning direction but without taking account of the at least one component in the wobbling direction.

Description

FIELD OF THE INVENTION The present invention relates to a method for the additive manufacturing of an object from a layer of powder, and to a device suitable for implementing such a method. PRIOR ART Additive manufacturing consists in producing an object by melting layers of powder that are superposed on one another. These layers correspond to various cross sections of the object that is to be manufactured. In order to melt a layer of powder, an energy source projects a beam of energy onto the surface of this layer of powder, in the form of a spot at which such melting occurs. The beam of energy is then controlled in such a way as to scan the surface in order to spread this melting over the entire surface of the layer. Conventionally, the beam of energy scans various zones of the surface in a longitudinal direction and in an outbound sense alternating with a return sense. Furthermore, it has been proposed for the energy source to be controlled in such a way that the spot travels over the surface not with a translational movement that is perfectly rectilinear in the longitudinal direction but in a movement made up of a translation in the longitudinal direction and of a wobbling movement. The wobbling movement notably oscillates at a high frequency and at a low amplitude in a transverse direction so as to enlarge the melt pool. The wobbling movement is typically obtained by orienting the beam at a range of angles, in the manner of a pendulum. It is furthermore desirable to exercise fine control over the size of the spot in order to avoid excessive fluctuations in the amount of energy applied to the layer per unit area. The size of the spot is dependent on the distance covered by the beam between the energy source and the surface, and this itself varies according to the angle of inclination of the beam with respect to the surface. The wobbling movement therefore contributes to causing the size of the spot to vary at high frequency. In order to illustrate this, FIG. 1 depicts the path of an energy beam projected onto a surface in a plane perpendicular to the longitudinal direction. In FIG. 1, the transverse direction is horizontal. The path of the beam is able to move about an axis parallel to the longitudinal direction and passing through a fixed point P. The notation used is as follows: S is the centre of the spot in the form of which the beam is projected onto the surface.r is the minimum distance between the points P and S.α is the half-angle of wobble of the beam.L is the distance between the point P and the surface S covered by the beam inclined at the angle α.A is the half-amplitude of wobble of the point S on the surface, in the transverse direction. During a wobble, the distance covered by the beam between the points P and the point S varies by a distance discrepancy d giving: d=L−r=√{square root over (r2+A2)}−r The value of this discrepancy d is very small. By way of example, for r=700 mm and A=0.3 mm, a value d=0.06 μm is obtained. In order to maintain a spot size that remains perfectly constant during the course of the scanning it would then be necessary for the focusing apparatus to take account of the wobble and therefore of this very small distance discrepancy d. SUMMARY OF THE INVENTION One object of the invention is to be able to exercise fine control over the amount of energy per unit area applied to a layer of powder by a beam of energy during the additive manufacturing of an object, while at the same time obtaining an enlarged melt pool, but without premature wearing of the energy source that emits the beam of energy. To this end, a first aspect of the invention proposes a method for the additive manufacturing of an object from a powder layer, the method comprising steps of: projecting a beam of energy onto a surface of the layer of powder in the form of a spot so as to melt the powder,scanning of the surface with the beam of energy so that the spot travels over the surface in a movement made up of a translation in a longitudinal direction of scanning and of a wobbling movement having at least a component in a direction of wobble,adjusting the focus of the beam of energy during the scanning according to the translation in the longitudinal direction of scanning but without taking account of the component of the wobbling movement in the direction of wobble. A focusing apparatus that adjusts the focus of the beam of energy according to the wobbling makes it possible to obtain a spot size that theoretically remains invariable over time. However, the inventors have found that a focusing apparatus configured in that way becomes worn very quickly because of the high frequency of the wobble oscillations and the low amplitude thereof. Therefore adjusting the focus of the beam of energy during the course of scanning without taking account of the component of the wobbling movement in the direction of wobble, as in the method according to the first aspect, makes it possible to avoid such premature wear