OPTICAL HEAD FOR POWDER SPRAY 3D PRINTING

Abstract

A powder dispensing head (1) for an additive manufacturing machine comprises a through-opening designed to allow the passage of a high-energy beam towards the melting point, a body (2) comprising N powder conveying ducts uniformly distributed about the through-opening and converging towards the melting point, a dispensing member (3) comprising a powder dispensing chamber having a powder inlet, and N powder outlets uniformly distributed about the through-opening, the body (2) and the dispensing member (3) being configured to be able to move relative to one another so as to fluidically connect or disconnect the powder outlets with respect to the respective powder conveying ducts according to the relative position of the dispensing member (3) with respect to the body (2).

Claims

1.-11. (canceled)

12. A powder dispensing head for an additive manufacturing machine, the powder dispensing head comprising: a through-opening configured to allow the passage of a high-energy beam toward a melting point; a body comprising N powder conveying ducts leading toward the melting point, the ducts being uniformly distributed about the through-opening and converging toward the melting point; a dispensing member comprising at least one powder dispensing chamber having an inlet for powder transported by a gas; and N powder outlets uniformly distributed about the through-opening in such a way that each powder outlet can be connected to a respective powder conveying duct, wherein the body and the dispensing member are configured to be able to move relative to one another so as to fluidically connect or disconnect a powder outlet with respect to a powder conveying duct according to a relative position of the dispensing member with respect to the body, and wherein N is greater than or equal to 2.

13. The powder dispensing head according to claim 12, wherein the dispensing member comprises: a first powder dispensing chamber having a first powder inlet and N first powder outlets uniformly distributed about the through-opening; and a second powder dispensing chamber having a second powder inlet and N second powder outlets, wherein the body and the dispensing member have at least one position in which the first powder outlets or the second powder outlets are fluidically connected to respective powder conveying ducts.

14. The powder dispensing head according to claim 12, wherein the dispensing member comprises: a first powder dispensing chamber having a first powder inlet and N first powder outlets uniformly distributed about the through-opening; a second powder dispensing chamber having a second powder inlet and N second powder outlets, wherein the dispensing member further comprises one or more powder mixing means simultaneously connecting a first powder outlet and a second powder outlet to a common powder conveying duct.

15. The powder dispensing head according to claim 13, wherein the body further comprises a powder recycling circuit configured to remove the powder to a recycling container, the dispensing member being configured to fluidically connect the first powder outlet or the second powder outlet to the recycling circuit when this outlet is disconnected from the conveying duct.

16. The powder dispensing head according to claim 15, wherein the body comprises two recycling circuits, each one configured to remove a powder to a respective recycling container, each first outlet and each second outlet being configured to be connected to a respective recycling circuit when they are disconnected from a powder conveying duct.

17. The powder dispensing head according to claim 15, wherein the dispensing member further comprises a purge gas dispensing chamber having a gas inlet and N gas outlets, the body and the dispensing member having at least one position in which the gas outlets are fluidically connected to a powder conveying duct, to the first recycling circuit, or to the second recycling circuit.

18. The powder dispensing head according to claim 13, wherein the body comprises N external powder conveying ducts configured to communicate fluidically with the powder outlets and configured to convey first powder or second powder toward the melting point.

19. The powder dispensing head according to claim 17, wherein the body comprises a number N of powder conveying ducts which are uniformly distributed about the through-opening and converge toward the melting point, the first recycling circuit and the second recycling circuit each having N inlets, each one adjacent to an inlet of a powder conveying duct, and wherein the first and second powder dispensing chambers and the gas chamber each have N outlets distributed on the ring so that each of the N outlets faces one of the N inlets of the body, N being greater than or equal to 2.

20. The powder dispensing head according to claim 12, further comprising a cooling circuit configured to circulate a liquid coolant between a liquid inlet and a liquid outlet.

21. The powder dispensing head according to claim 20, wherein the powder dispensing head being obtained by additive manufacturing and the cooling circuit being in a form of an inbuilt network passing through various external and internal parts of the body.

22. A powder jetting additive manufacturing machine comprising the powder dispensing head according to claim 12.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0067] The invention will be better understood and further features and advantages will become apparent from reading the description which will follow, the description referring to the attached drawings, among which:

[0068] FIG. 1 is a schematic and partial view of a known 3D printing facility according to the prior art;

[0069] FIG. 2 is an overall view of a printing head according to the invention;

[0070] FIGS. 3 and 4 respectively depict a dispensing member and a main part of a body of the head according to FIG. 2;

[0071] FIGS. 5 and 6 are vertical cross sections of the dispensing member of FIG. 3 and of the main body of FIG. 4, respectively;

[0072] FIG. 7 is a view in vertical section of the printing head according to FIG. 2;

[0073] FIG. 8 is an exploded view of a body of a printing head according to the invention;

[0074] FIGS. 9 and 10 are two variants of the head of FIG. 2;

[0075] FIG. 11 is a view in section of a printing head equipped with means for mixing two powders;

[0076] FIG. 12 and FIG. 13 depict a variant of the head of FIG. 11 allowing a mixture of powders to be created in the cold state.

DETAILED DESCRIPTION

[0077] FIG. 1 shows an example of a known powder jetting 3D printing facility of the prior art. The facility comprises a printing head T connected to a first source A of powder PA, and to a second source B of powder PB. To manufacture an object M, a conveying duct P conveys the powders PA, PB as far as a melting point F at which a beam emitted by a laser source L melts these powders separately or in the form of a mixture. With each powder being transported by a carrier gas, a recycling system allows the unused powders PA, PB to be recovered in respective powder recovery containers RA, RB.

[0078] In other instances, which have not been illustrated, the facility may be a single-material facility or else may comprise a greater number of powder sources.

[0079] The facility also comprises a source of purge gas G, as well as a powder dispensing system, also known as a switchover system C. This system allows the sources A, B of powder PA, PB and the source of gas G to be connected to and disconnected from the conveying duct P or the powder recovery containers RA, RB.

[0080] The facility finally comprises a movement system Z for moving the printing head T and a movement system D designed for moving the object M particularly during manufacture in the two directions of the plane X, Y. Finally, a control system CT controls the facility.

[0081] The facility may also comprise a device, not illustrated, for metering the powders PA and PB.

[0082] The powders may be metallic powders such as: carbon steels and stainless steels, or any metal alloys, for example: nickel bases, cobalt bases, alloys of titanium, of copper or of aluminium, ceramics, intermetallic compounds, and also polymers or other composites. They may be used separately or in distinct layers to manufacture complete components, to repair worn components or to surface-coat metallic components.

[0083] Furthermore, in the example illustrated, the powder dispensing system is in the facility but distant from the head T. However, in most known 3D printers, the powder dispensing system is outside the printer.

[0084] FIG. 2 shows an overall view of a powder dispensing head 1 according to a first embodiment of the invention. The head 1 comprises a body 2 of conical overall shape, and a dispensing member 3.

[0085] FIG. 3 shows a first exemplary embodiment of a dispensing member 3. In this exemplary embodiment, the dispensing member 3 is in the form of a ring.

[0086] In other exemplary embodiments which have not been illustrated, the dispensing member may have a shape different from that of the ring. For example, the dispensing member may have the shape of a disc or a rectangular shape.

[0087] FIG. 4 depicts a partial view of a body 2. More specifically, FIG. 4 shows part of the body that will be referred to as main body 2A in the remainder of this description.

[0088] The main body 2A in the example illustrated is of cylindrical overall shape and has a bore 20 in the form of a ring intended to accept the ring of the dispensing member 3. It also has a through-opening 0 through which the laser beam L passes, as described with reference to FIG. 1.

[0089] The ring of the dispensing member 3, when the head is assembled as illustrated in FIG. 2, is in contact with the main body 2A. More specifically, the ring is inserted into the bore 20 of the main body 2A. The two components 2A and 3 are arranged in such a way that the ring can rotate with respect to the main body or, vice versa, if the ring is fixed, then it is the main body that rotates with respect to the ring.

[0090] FIG. 5 shows a view in vertical section passing through the axis of rotation of the ring 3. As has been shown, the ring 3 has an annular first chamber 31 intended for dispensing a first powder PA. The first chamber 31 has a powder inlet 311 intended to be connected to a source of the first powder PA. It also has a plurality of powder outlets 312 enabling the powder PA to be dispensed.

[0091] The ring 3 also has a second chamber 32 intended for dispensing a second powder PB. The second chamber 32 has a powder inlet 321 intended to be connected to a source of the second powder PB. It also has a plurality of powder outlets 322 enabling the second powder PB to be dispensed.

[0092] The ring 3 furthermore has a third chamber 33 intended for dispensing a purge gas G, such as argon. The third chamber 33 has a gas inlet 331 intended to be connected to a source of the purge gas. It also has a plurality of gas outlets 332 enabling the purge gas G to be dispensed.

[0093] The outlets of the three chambers 31, 32, 33 are arranged uniformly so that each set of three successive outlets has to comprise a first outlet 312 of the first chamber 31, a second outlet 322 of the second chamber 32, and a third outlet 332 of the third chamber 33.

[0094] FIG. 6 shows a view in vertical cross section through the main body 2A of FIG. 4 and passing substantially through the central axis thereof.

[0095] The main body 2A has a plurality of powder conveying ducts 21 which carry the powder as far as the melting point. Each duct 21 has an inlet 221 designed to face a powder outlet 312, 322 or a gas outlet 332. One of these ducts 21 is visible in FIG. 6.

[0096] The main body 2A also comprises two powder recycling circuits 22, 23 configured to remove the powder to recycling containers RA, RB respectively.

[0097] The first recycling circuit 22 has a plurality of inlets 221 and an outlet 222 as shown in FIG. 4. The second recycling circuit 23 has a plurality of inlets 231 and an outlet 232 as shown in FIG. 4. The outlets 222 and 232 are intended to be connected to the recycling containers RA, RB respectively.

[0098] Advantageously, the number of powder conveying ducts 21, and the number of inlets 221, 231 of each recycling circuit 22, 23 is equal to the number of powder outlets 312, 322 and to the number of gas outlets 332. The inlets 211, 221, 231 of the conveying ducts 21 and of the recycling circuits 22, 23 are arranged uniformly so that each set of three successive inlets has to comprise an inlet 211 of a conveying duct, an inlet 221 of the first recycling circuit, and an inlet 231 of the second recycling circuit.

[0099] By way of example, as the dispensing ring 3 rotates with respect to the body 2, the following configurations are possible.

[0100] Configuration 1: injection of the first powder PA.

[0101] Each first outlet 312 for powder PA is fluidically connected to a powder conveying duct 21. In this case, the component is manufactured based on the first powder PA;

[0102] each second powder outlet 322 is connected to an inlet 231 of the second recycling circuit 23 to recycle the second powder PB; and

[0103] each gas outlet 332 is connected to an inlet 221 of the first recycling circuit 22 so as to purge this circuit of the residue of the first powder PA, which residue is sent to the container RA.

[0104] According to an alternative usage, when the powder PB is not needed, its supply can be cut off.

[0105] Configuration 2: injection of the second powder PB.

[0106] Each second outlet 322 for powder PB is fluidically connected to a powder conveying duct 21. In this case, the component is manufactured based on the second powder PB;

[0107] each first outlet 312 for powder PA is connected to an inlet 221 of the first recycling circuit 22 to recycle the first powder PA; and

[0108] each gas outlet 332 is connected to an inlet 231 of the second recycling circuit 23 so as to purge this circuit of the residue of the second powder PB, which residue is sent to the container RB.

[0109] According to an alternative usage, when the powder PA is not needed, its supply can be cut off, and the recycling gas can be cut off as soon as the circuit is purged.

[0110] Configuration 3: injection of powder cut off.

[0111] Each gas outlet 332 is fluidically connected to a powder conveying duct 21. In that case, the injection of powder at the melting point is cut off;

[0112] each first outlet 312 for powder PA can be connected to an inlet 221 of the first recycling circuit 22 to recycle the first powder PA; and

[0113] each second powder outlet 322 can be connected to an inlet 231 of the second recycling circuit 23 to recycle the second powder PB.

[0114] As shown in FIGS. 4 and 6, the main body 2A may also comprise a cooling circuit 24 configured to circulate a liquid coolant between a liquid inlet 241 and a liquid outlet 242. Likewise optionally, the main body may comprise a duct 27 for supplying the through-opening 0 with a stream of gas. This stream of gas serves to prevent powder from being drawn back into the through-opening 0.

[0115] The main body may also comprise a supply duct 28 supplying a stream of gas to the melting point. This stream of gas serves to adapt the size of the area covered by the powder, particularly by preventing it from being focused too narrowly into a point. This contributes to better melting of the powder by the laser beam.

[0116] FIG. 7 shows a vertical cross section through the printing head 1 illustrated in FIGS. 2 to 6. This view shows the layout of the body 2 with the dispensing member 3 as described hereinabove.

[0117] In the embodiment of FIG. 7, the body 2, as also illustrated in FIG. 8, is of conical overall shape and comprises three parts:

[0118] a main body 2A which comprises a base 25 of the cone and an upper part 21A of the powder conveying duct(s) 21;

[0119] an intermediate body 2B of conical shape, comprising a lower part 21B of the powder conveying duct(s) 21; and

[0120] an outer body 2C that fixes the intermediate body 2B to the main body 2A and that forms the vertex of the cone 26.

[0121] This advantageous configuration simplifies the maintenance of the printing head in comparison with the existing models.

[0122] FIG. 9 illustrates a variant of the 3D printing head according to the invention. This head 1′, with a 90° elbow, is chiefly intended for the addition of material, for example in order to make a repair, inside a tube TB, particularly tubes having an inside diameter greater than or equal to 100 millimetres.

[0123] The main difference compared with the printing head 1 described hereinabove lies in its shape having a 90° elbow reducing the height of the connections and other components known from the prior art situated above the dispensing member 3. These connections are arranged mainly on one side of the dispensing member 3. This allows easy insertion inside a tube.

[0124] More specifically, the head 1′ comprises a mirror MR able to reflect the laser beam L towards the melting point.

[0125] FIG. 10 illustrates a variant of the 3D printing head 1′ of FIG. 9. The head 1″ further comprises a quick-coupling system CR on the base of the head 1″. This quick-coupling system CR allows for rapid head maintenance and replacement.

[0126] FIG. 11 illustrates a second embodiment in which the head 5 comprises a body 6 substantially similar to the body 2 of the head 1 of FIG. 2. The main difference lies in the dispensing member 7. In the example shown in FIG. 11, the dispensing ring 7 comprises two dispensing chambers 71, 72 having powder inlets 711, 721 respectively. It also comprises a mixing means configured to send into the powder conveying ducts 21 a mixture made up of a proportion of the first powder PA leaving the first chamber 71 and a proportion of the second powder PB leaving the second chamber 72.

[0127] The mixing means may, for example, comprise pairs of canals, one connected to the first chamber 71 and the other to the second chamber 72 and which converge (crossed convergence) towards an inlet 211 of a powder conveying duct 21.

[0128] The proportional metering of two powders PA, PB allows the manufacture of parts that are variable according to the concentrations of the powders PA and PB.

[0129] In that case, a device, which has not been illustrated, for metering the powders PA and PB is provided outside the head 5.

[0130] In embodiments which have not been illustrated, proportional mixtures of 3 or more powders are used.

[0131] FIGS. 12 and 13 depict a variant of the head of FIG. 11 allowing the creation of a mixture of powders in which mixture one of these powders is not heated as strongly because it is passed through the exterior ducts 92.

[0132] Alternatively, only the exterior ducts 92 are supplied with powder.

[0133] The powder dispensing head 8 comprises a body 9 and a dispensing member 10.

[0134] The dispensing member 10 is substantially similar to the dispensing member 7 of the head 5 described previously. The dispensing member 10 differs in that it does not comprise a mixing means allowing a mixture of powders to be carried to the powder conveying duct 21.

[0135] The dispensing member 10 comprises a first powder dispensing chamber 101 with a powder inlet 1011 and one or more powder outlets (which are not visible in FIG. 13), each of which is intended to inject the first powder PA into a powder conveying duct 21. It also comprises a second powder dispensing chamber 102 with an inlet 1021 for powder PB and one or more powder outlets 1022.

[0136] The body 9 is similar to the body 6 described with reference to FIG. 11. It comprises a main body 9A, an intermediate body 9B and an external body 9C. The main body 9A further comprises internal ducts 91 allowing the outlets 1022 to be connected to the periphery of the main body 9A.

[0137] The body 9 further comprises an additional body 9D, for example in the form of a ring which is screwed around the main body. The additional body 9D comprises powder-conveying external ducts 92 designed to communicate fluidically with the powder outlets 1022 via the internal ducts 91. In this way, the second powder PB is conveyed to the melting point via the external ducts 92 and mixed, cold, into the molten pool.