EP3481582A1

EP3481582A1 - Additive manufacturing process using discrete surface elements

Info

Publication number: EP3481582A1
Application number: EP17742505.5A
Authority: EP
Inventors: Olivier Martin; Arnaud De Ponnat
Original assignee: Mecachrome France SAS
Current assignee: Mecachrome France SAS
Priority date: 2016-07-08
Filing date: 2017-07-07
Publication date: 2019-05-15
Also published as: FR3053631B1; WO2018007769A1; FR3053631A1

Abstract

The present invention concerns an additive manufacture process for manufacturing a blank of a metal object from a digital object, by adding metal material to a support that is itself metal, combined with a supply of energy. The metal material is added in the form of several discrete surface elements (1, 1', 2), the energy supply allowing the elements to be welded to the support (3) in at least two passes, i.e. a first pass and a second pass, each surface element being defined by a length (L, l) along which it is welded to the support, a height (h) by which it protrudes from the support after being welded thereto, and a thickness (e) in a plane substantially perpendicular to that defined by the height (h) and the length (L, l) of the element, the height of the element being greater than the thickness of same, the process comprising a step of removing material, carried out in the dry state, from at least one of the elements of the first pass before carrying out the second pass.

Description

ADDITIVE MANUFACTURING METHOD USING DISCRETE SURFACE ELEMENTS

The present invention relates to the technical field of additive manufacturing.

Classically, this term denotes the set of methods for making by adding material, layer by layer, a physical object from a previously defined digital object.

These additive manufacturing processes are the opposite of material removal or subtractive processes, which make it possible to obtain metal objects from thick plates or hollow cylinders.

Metal objects can also be obtained from forged blanks or foundry crudes near the ribs.

However, all these methods require the use of a large amount of material relative to that present in the final part. The corresponding ratio can be as high as 30: 1, particularly in the field of aeronautics, where it is called "Buy to Fly ratio" in English terminology.

In addition, they require the implementation of heavy industrial means and lead to very high realization costs that increase with the dimensions of the object to be manufactured.

This is why additive manufacturing processes are developed to obtain metallic objects which proceed by local supply of metal for example in the form of powder or wire, and energy for example in the form of a laser beam, of an electron beam, an electric arc or plasma. These methods are commonly referred to as DMD (Direct Metal Deposition) in English terminology.

It is thus possible to provide a flow of gas driving metal powder, moving above a metal support with a laser beam that causes the powder to melt, which is deposited in the molten state on the support itself. slightly melted and solidifies on this one. Each movement of the beams creates a layer that is superimposed on the previous ones. In general, the height of each layer after melting is less than the thickness of the deposited bead.

These methods are in particular proposed in the field of aeronautics to reduce the amount of total material used relative to that of the final part and generally reduce manufacturing costs.

These methods, however, have disadvantages.

Indeed, the deposition of molten metal leads to high stresses during its solidification and thus the deformation of the support.

In addition, the control of the melting is difficult and the deposited material may, after solidification, have defects. That is why it is necessary to practice a nondestructive control of any volume built on the support.

In addition, the rate or rate of removal of the metal is relatively low. By way of example, for titanium TA6V, the deposition rate can only reach 5 to 10 kg / h, when producing metal parts for the aeronautical industry.

Finally, the cost of metal in the form of powder or wire is relatively high, which further contributes to making the implementation of additive manufacturing processes expensive.

The object of the invention is to overcome these drawbacks by proposing a radically different additive manufacturing process of high efficiency.

Thus, the invention relates to a method of additive manufacturing of a blank of a metal object from a digital object, by supplying metallic material on a support itself metal, combined with a supply of energy, characterized in that the supply of metallic material in the form of a plurality of discrete surface elements is provided, the supply of energy making it possible to weld said elements to said support in at least two passes, namely a first pass and a second pass , each surface element being defined by a length in which it is welded to said support, a height in which it protrudes from said support after having been welded thereto, and a thickness in a substantially perpendicular plane to that defined by the height and length of the element, the height of the element being greater than its thickness, the method comprising a step of removing material, r dry-stamped at least one of said elements of the first pass before making the second pass.

This method makes it possible to rough out a metal object more rapidly, the removal rate metal being much more important when it is brought in the form of discrete surface elements whose height is greater than the thickness, than when it is in the form of powder or wire.

Moreover, the cost of the material in the form of surface elements is much lower than that of a material in powder or wire form.

Finally, the metal support and the surface elements can come from the same room, which allows the blank to be made with a single material from the same batch material.

In advantageous embodiments, one and / or the other of the following provisions is also used:

at least one of said elements of the first pass comprising at least one face by which it is intended to be soldered to an element of another pass, the step of removing the material is carried out on said at least one face;

- The elements of the first pass are welded to the support, spaced from each other;

the removal of material is of the type assisted by a cryogenic fluid;

the removal of material is carried out with an addition of liquid nitrogen or C0 ₂ ;

- The elements are welded successively, a material removal step being performed after the deposition of an element, for at least a portion of said elements;

- The elements are welded in a first series of which at least two are spaced and a second series being interposed in the space or spaces formed between the elements of the first series, a material removal step performed at dry being provided in said one or more spaces, between the welding of the first series and that of the second series;

a step of removing material is carried out on the support;

this step is performed before the welding of discrete surface elements on the support and consists of delimiting the areas of the support intended to receive said elements to achieve an end-to-end assembly;

this step is performed between two elements welded successively on the support, in a direction substantially perpendicular to the direction in which said elements extend;

at least two elements are welded together before being welded to the support;

welding is performed without fusion;

said elements and said support come from the same piece.

The invention also relates to a device for the additive manufacturing of a blank of a metal object from a digital object, said device comprising means for welding discrete metal surface elements on a metal support itself and means to perform a removal of material on said elements and / or said support.

It also relates to a method of manufacturing a metal object from a blank obtained by the method according to the invention described above, this manufacturing method comprising a step of removing material on this blank to obtain said metal object. The invention finally relates to a blank of a metal object and a metal object obtained by the methods according to the invention.

In particular, the invention relates to a metallic component of an aircraft obtained by the methods according to the invention, that is to say a component of the structure of the aircraft or its propulsion means.

The invention will be better understood and other objects, advantages and characteristics thereof will appear more clearly on reading the following description of non-limiting examples of implementation of the invention, with reference to the accompanying drawings. on which ones :

Figures 1 to 4 are perspective views illustrating the implementation of the method according to the invention on a plane support.

Figure 4A illustrates a detail of Figure 4.

Figures 5 to 9 are perspective views illustrating a variant of the implementation of the method according to the invention on a plane support.

Figure 10 is a view of the metal object obtained from the blank shown in Figures 4 and 9.

Figure 11 is a perspective view illustrating the implementation of the method according to the invention on a cylindrical support, with discrete surface elements.

Figure 12 is a top view of detail A of Figure 11.

Figure 13 is a perspective view illustrating the implementation of another variant of the method according to the invention on a cylindrical support with discrete surface elements. FIG. 14 is a view from above of detail A of FIG. 13.

Figures 15 to 18 are perspective views illustrating another alternative embodiment of the invention on a plane support.

Figure 19 is a perspective view illustrating another alternative embodiment of the method according to the invention on a plane support.

Figures 20 and 21 are two perspective views, illustrating another variant of the method illustrated in Figures 5 to 9.

Fig. 22 is a perspective view illustrating another step of the method according to the invention.

The elements common to the different figures will be designated by the same references.

A first example of implementation of the method according to the invention will be described with reference to Figures 1 to 4A.

This additive manufacturing process is intended to obtain a blank of the metal object illustrated in FIG.

In the first place, this object is decomposed into discrete surface elements.

Preferably, these discrete elements have the largest possible dimensions, given the geometry of the object to be obtained and the welding capacity of the technology implemented.

In the example illustrated in FIGS. 1 to 4, the discrete surface elements 1, 1 'and 2 have a trapezoidal shape. Thus, the elements 1 and 1 have an isosceles trapezoidal section, while the elements 2 have a rectangular trapezoidal section. The element 1 is defined by two faces 16 forming an isosceles trapezium, with two parallel bases 10 and 11, the length L of the base 10 being greater than the length 1_ of the base 11.

The two bases 10 and 11 are connected by two sides 12 and 13 having the same inclination with respect to the base 10 and relative to the base 11.

Each pair of sides 12 or 13 defines a side face 14, 15 extending between the bases 10 and 11.

Each element 1 has a height h corresponding to the distance between the bases 10 and 11.

Each element 1 also has a thickness e which is counted between the two faces 16 or in a plane substantially perpendicular to that defined by the height h and the length L or _1.

Element 2 is illustrated in more detail in Figure 4A.

It is defined by two substantially flat faces 26 and having the shape of a rectangle trapezium.

Each trapezoidal face is defined between two parallel bases 20 and 21, the base 20 having a length L ₂ greater than the length I ₂ of the base 21.

These two bases are connected by sides 22 and 23, the angle formed by the side 22 with the base 20, on the one hand and the base 21, on the other hand, being a right angle.

The element 2 has a height h corresponding to the distance between the bases 20 and 21 and a thickness e corresponding to the distance between the two trapezoidal faces 26 and which is therefore measured in a plane substantially perpendicular to that defined by the height h and the length L or _1. Each pair of sides 22 or 23 defines a side face 24, 25 extending between the bases 20 and 21. The face 24 is perpendicular to the bases 20 and 21.

Moreover, the bases 20 define a face 27 and the bases 21 a face 28, the faces 27 and 28 being substantially parallel.

This element 2 can be obtained by cutting an element 1.

In general, the height h of the elements 1 or 2 is greater than their thickness e.

The discrete surface elements are then made, for example by cutting in a metal sheet.

FIG. 1 illustrates a first step of the method in which metal elements 1 are welded to the support 3, also metallic, in a first arc of a circle. This is a T (or L) assembly.

The elements 1 are welded to the support 3 by their face 17 defined by the bases 10, that is to say along their great length L.

Moreover, they are spaced from each other by a distance corresponding to their short length 1.

This step corresponds to a first pass.

The welding of the elements 1 can be carried out by any suitable method and in particular a linear friction welding (LFW for Linear Friction Welding in the English terminology) or a pressure method using high temperature plasmas (for example an SPS process) for Spark Plasma Sintering in English terminology or a process of sputter welding or flash butt welding in English terminology). In a known manner, a linear friction welding process is a solid phase welding process, the materials not being melted, and which does not require filler materials.

The assembly is performed by rubbing against one another the surfaces to be assembled, under a controlled pressure. The advantages of solid state welding are the preservation of the properties of the materials as well as the possibility of assembling between heterogeneous materials.

However, the linear friction welding process leads to the formation of burrs at the interface of the welded parts, here between the elements 1 and the support 3.

Also known, a method of the SPS type is based on the use of high temperature plasmas, momentarily generated between powder particles, by an electric discharge. The heating and cooling speeds are high and the temperature maintenance is generally short. The densification of the material can therefore be done at a relatively low temperature, which qualifies this method of fusion welding process.

It therefore has the same advantages as non-fusion welding processes. Compared to a method of the LFW type, it has the additional advantage of avoiding the backflow of material at the interface between two welded parts and thus the formation of burrs. It can nevertheless cause deformations.

Once the elements 1 welded on the support 3, according to the first pass illustrated in Figure 1, the next step of the process consists of a removal of material, such as a machining, on the elements 1. The removal of material can also be achieved by grinding. This step is illustrated in Figure 2.

This material removal step is performed dry.

It may especially be assisted by a cryogenic fluid, that is to say with a liquid nitrogen supply or C0 ₂ .

In this respect, it should be noted that a machining lubricant is intended to reduce friction on cutting objects and to remove some of the heat generated by deformation, breakage, and friction during cutting. .

However, a cryogenic fluid necessarily has the effect of evacuating heat efficiently and quickly and without contaminating the support.

Thus, the cryogenic fluid performs the function of a machining lubricant, which does not pollute the support.

This step of removing material is intended to remove the burrs that may result from the previous welding step and, in general, to prepare the side faces 14 and 15 of the elements 1 already welded which will be in contact and be welded with other elements that will be welded to the support in a second pass.

In the method illustrated in Figure 2, at least the faces 14 and 15 facing two successive elements 1 of the first series of elements welded to the support will be machined. The removal of material on the faces 14 and 15 makes it possible to remove the burrs at this level and to adjust the clearances for the subsequent welding of the elements (see FIG. 3). Similarly, the support 3 will be subjected to a material removal step, such as machining, between two successive elements 1 of this first series and in a direction substantially perpendicular to that in which these elements 1 extend. passage of the material that will escape from the interface between the elements welded in a second pass and the support 3. Similarly, a portion of the two faces 16 of an element 1 will be machined. Thus, the references 16b and 16c identify the two zones of the faces 16 of an element 1 which are machined. These two lateral zones are in the extension of the faces 14 and 15 and surround the central zone 16a which protrudes with respect to these lateral zones.

FIG. 3 illustrates the next step of the method, in which the second pass consists in welding a second series of elements 1 'which are interposed in the spaces formed between the elements 1 of the first series, illustrated in FIG. 1 This is made possible by the fact that all the elements 1, 1 have the same shape and the elements 1 are spaced by a length _1.

These elements are identical to elements 1 and the references concerning the elements will be the same as those concerning the elements 1, affected by the index '' '.

FIG. 3 thus illustrates the elements 1 of the first series and the elements 1 'of the second series which are all welded on the support 3 with the exception of a single element 1'.

Figure 3 shows that the elements are welded to the support 3 by their short length _1, or by their face 18 'defined between their bases 11', and on the faces 15, 14 of the adjacent elements 1 by their faces 15 'and 14'. The elements 1 and the are therefore arranged head to tail.

The elements are welded to both the support and the elements 1 by any suitable welding process and, preferably, by a non-fusion welding process, as previously described.

With this step of the method, a full arc 4 is obtained.

The method according to the invention is again implemented to obtain the second arc 5 formed of three elements 1, welded to the support by their long length L or by their face 17 and by two elements welded to the support by their short length _1, corresponding to their face 18 ', the elements being interposed between two elements 1 spaced from the length _1.

As described previously with regard to FIG. 2, a step of removing material is carried out on the elements 1 and on the support 3, between the elements 1 previously welded, before proceeding to the welding of the elements 1 'on the support 3 and on the elements 1.

This second arc 5 is concentric to the first arc 4 and has a length less than that of the latter.

The bar 6 connecting the two circular arcs 4 and 5 is obtained by welding on the support 3 an element 1 ', by its base 11 of length 1, and both on the support and on the element 1' and an element 1 of the arc 4 or the arc 5, an element 2 as shown in Figure 4A.

Similarly, between the welding of the element 1 'and the welding of the elements 2, a material removal step is carried out on the element 1' and on the support 3, in particular for eliminating burrs and machining the surfaces 14 'and 15' of the element 1 '.

FIG. 4 illustrates the result obtained which consists of a blank of the object 9 illustrated in FIG.

Of course, the invention is not limited to the method which has just been described and, in particular, the elements 1, 1 'may not be welded in two successive series but for example be welded successively or by series comprising a lower number of elements or a higher number of series (or passes). Similarly, two elements could be previously welded together before being welded to the support. This can, for example, be the case for the element 1 'and the two elements 2 forming the bar 6.

In addition, instead of an element 2, could be provided an element 2 'as illustrated in Figure 19.

This element 2 'is obtained from a block extracted from a support 3' whose thickness is greater than that of the support 3 (for example equal to twice this thickness) thanks to machining operations.

It is understood that this element 2 'is used in place of an element 1 and an element 2.

Furthermore, the method is not limited to the shape of the elements 1, 1 'and 2 which have been illustrated in Figures 1 to 4A. It is understood that the shape of the discrete surface elements can be adjusted according to the final object to obtain. In particular, the elements successively welded to the support do not necessarily have identical shapes.

It should however be noted that the method can advantageously be implemented with elements which are, in a very large proportion, of identical or almost identical size and shape. These standard elements may represent at least 90% of the metallic material provided to produce an object with the method according to the invention.

Of course, the size and shape of these standard elements depend on the welding capacity of the technology used and can be adapted to the specificities of the object to be manufactured. These standard elements can therefore vary in shape and dimensions from one object to another.

Furthermore, it is appropriate that the elements are defined so that the surfaces to be welded have a substantially identical shape and dimensions.

Finally, the blank of the object to be produced could comprise more than one layer of elements welded to the support, that is to say at least two successive layers, as is conventional in an additive manufacturing process.

When constituting the circular arcs 4 and 5 and the bar 6, the material removal steps do not cause pollution of the support or the welded elements since they are made dry.

Furthermore, these steps do not cause deformation of the support or surface elements when they are assisted by a cryogenic fluid.

Reference is now made to FIGS. 5 to 9 which illustrate an alternative embodiment of the method illustrated in FIGS. 1 to 4.

First, according to this method, the discrete surface elements 1, 1 'and 2 described with reference to FIGS. 1 to 4A are taken directly from the support 3.

The recesses 31 correspond to elements 1 or 1', while the recesses 32 correspond to the elements 2.

Thus, the elements and the support come from the same piece, which contributes to the quality of the object finally obtained.

This method also differs from the previous one in that removal of material is carried out on the support 3 before any discrete surface element is assembled thereon. This removal of material, including machining, consists of delimiting the areas of the support on which the discrete surface elements will be welded.

Thus, the zone 33 of the support is at the same level as the rest of the upper face 30 of the support and is surrounded by a zone 34 (shown shaded) whose level is lower than that of the upper face 30 of the support.

The zone 33 thus delimited comprises a first zone 34 in an arc whose concavity and length correspond to the first arc of circle 4 of the blank; a second zone 35 in an arc substantially concentric with the zone 34 and whose length corresponds to the second circular arc 5 and a right zone 36 connecting the zones 34 and 35 and corresponding to the positioning and the length of the bar 6 of the 'draft.

The thickness E of each zone 34, 35, 36 corresponds substantially to the thickness e of each element 1, 1 ', 2.

This prior machining of the support 3 will allow for an end-to-end assembly of the elements of discrete surface on the support, that is to say an assembly in which the contact surfaces of two welded parts are identical.

FIG. 6 illustrates the next step of the method in which the metal elements 1 are welded to the first arcuate zone 34 as well as to the second arcuate zone 35.

The elements 1 are spaced from each other, an element 1 being present at each end of the zones 34 and 35.

The elements 1 are welded to the zones 34 and 35 by their face 17 defined by the bases 10, that is to say along their great length L.

Furthermore, the elements 1 are spaced from each other by a distance corresponding to their short length _1.

This step corresponds to a first pass of the process.

As explained previously with reference to FIGS. 1 to 4, the welding of the elements 1 is preferably carried out by a non-fusion welding process.

Once the elements 1 welded to the zones 34 and 35 of the support, the next step of the process consists of a removal of material on the elements 1.

As explained above, this material removal step is carried out dry and it is preferably assisted by a cryogenic fluid.

This material removal step concerns the faces 14 and 15 facing two successive elements 1 of the first series of elements welded to the support, as well as the faces 16 of the elements 1.

As shown in FIG. 7, the faces 16 of the elements 1 are only partially machined so as to delimit a central zone 16a which protrudes with respect to the zones 16b and 16c located on either side of this central zone 16a and in the extension of the lateral faces 14 and 15.

Similarly, the first and second zones 34 and 35, as well as the right zone 36, are subjected to a step of removal of material between two successive elements of this first series. This removal of material is carried out in a direction substantially perpendicular to that in which the elements 1 extend.

In general, these material removals (shown with hatching) are intended to prepare the surfaces of elements 1 already welded which will be in contact and welded with other elements, welded in a second pass.

FIG. 8 illustrates the result obtained after welding of the second series of elements 1 'which are positioned in the spaces formed between the elements 1 of the first series.

As explained above with respect to FIG. 3, these elements are welded to the first zone 34 or the second zone 35 by their surface 18 'defined between their bases 11'.

At the end of this second pass, are obtained a first and a second circular arcs 4 and 5 complete.

FIG. 8 illustrates the beginning of the third pass in which an element 1 'and two elements 2 will be soldered on the right zone 36 to obtain a bar 6.

Thus, the third pass of the method according to the invention consists here in welding an element 2 on one of the elements 1 located on either side of the zone 36, so that its right face 24 is welded to the zone 16a of the element 1 and that its base

20 is welded to the zone 36.

Preferably, the surface of the zone 16a coincides with the right face 24 to make an end-to-end connection.

The element is then welded, this element being welded to the zone 36 by its face 18 'and on the inclined face 25 of the element 2 already welded, by its face 15'.

Finally, the second element 2 is welded to both the zone 36 by its face 27, on the face 14 'of the element 1' and on the face 16a of the element 1 already welded and present on the second zone 35. .

It is understood that the inclined face 25 of the element 2 advantageously makes an angle with its bases 20 and 21 which is complementary to that made by the inclined faces 14 'and 15' with the bases 10 'and 11' of the element 1 '.

FIG. 9 illustrates the blank obtained at the end of this third pass of the method and which corresponds to the object illustrated in FIG.

This sketch is similar to that shown in Figure 4.

Reference is now made to FIGS.

21 which illustrate an alternative embodiment in which a bar 6 as illustrated in Figures 4 and 9 is obtained from elements 1 and 1 ', without elements 2 are necessary.

Figure 20 is a view similar to Figure 6 in which the elements 1 have a greater thickness. These elements have been welded according to the two arcuate zones 34 and 35, as illustrated in FIG. 6.

A material removal step is then carried out on the faces 14 and 15 facing two successive elements 1 as well as the faces 16 of the two elements 1 facing each other and present on the zones 34 and 35. This removal of material is performed on the central portion of the faces 16 so as to create a face 16d complementary to the face 15 'of the element 1' which will subsequently be welded.

Moreover, the removal of material is also performed on the right zone 36 and the arcuate zones 34 and 35, between two elements 1 already welded.

FIG. 21 is a view similar to FIG. 9 and illustrates the result obtained after elements 1 'have been placed in the spaces formed between the elements 1 of the first series (illustrated in FIG. 20) and welded on the zones 34 and also on the elements 1. Furthermore, an element has also been welded to the right zone 36 between the two elements 1 vis-à-vis to form the bar 6. Its size is adapted to the space between the two elements 1.

FIG. 22 illustrates a second layer of elements 1 and partially formed on the first layer illustrated in FIG. 9 and more precisely on the first circular arc 4.

This second layer 4 'is, like the first, made by first welding the elements 1 on the first layer, removing the material on the side faces 14 and 15 of the elements 1 vis-à-vis and possibly on their faces 16 and by welding the elements 1 'on the elements 1 already welded.

This second layer may or may not extend along the entire arc 4 and it may also be performed on all or part of the bar 6 and / or the second arc 5.

The object 9 illustrated in Figure 10 is obtained by cutting the support 3 and proceeding to a suitable material removal step.

It is understood that, during this step, the amount of material that will be removed will be very small compared to that which would result from the machining of a blank rough forging or a foundry blank.

Moreover, compared to additive manufacturing processes in which the metal supply is carried out in powder or wire form, the process according to the invention is much less expensive to implement, the discrete surface elements being a low realization cost given the volume provided, compared to a metal powder, for example.

Moreover, the rate of metal deposition is considerably increased compared with conventional processes using a powder or wire, insofar as the metallic material is provided in the form of a surface element whose height is substantially greater than the thickness. .

Finally, as underlined above, the variant of the method according to the invention described with reference to FIGS. 5 to 9 makes it possible to produce the entire object from the same material batch, which contributes to the good mechanical properties presented by this object. . Reference is now made to FIGS. 15 to 18 which illustrate another variant of the method illustrated in FIGS. 1 to 4.

For the sake of simplification, this variant is described relative to the single arc 4, consisting of elements 1 and 1 '.

As in the variant of the method illustrated in FIGS. 5 to 9, material is removed on the support 3 before any discrete surface elements are assembled on it. However, this removal of material is not carried out along the entire length of the arc 4 as in the variant of the method illustrated in FIG. 5, but only on portions of an arc having a length L 'slightly greater than the long length L of an element 1, the.

Thus, FIG. 15 illustrates a series of six pairs of grooves 37a, 38a of length L '.

The grooves 37a extend along a first arc 37.

The grooves 38a extend along a second arc 38 whose radius is smaller than that of the first arc 37.

Two adjacent pairs of grooves 37a, 38a are spaced from each other by a distance l less than the short length 1 of an element 1, 1 '.

The thickness E of the support 3 between two grooves 37a, 38a of the same pair is substantially equal to the thickness e of each element 1, 1 ', 2.

FIG. 16 illustrates the next step of the method in which each metal element 1 is welded to an arcuate zone 39 delimited between two grooves 37a and 38a. The elements 1 are welded to the zones 39 by their face 17 defined by the bases 10, that is to say along their great length L.

This step corresponds to a first pass of the process.

Once the elements 1 welded on the zones 39 of the support, the next step of the process consists of a removal of material on the elements 1.

This material removal step concerns the faces 14 and 15 facing two successive elements

1 of the first series of elements welded on the support, as well as the faces 16 of the elements 1.

As shown in FIG. 17, the faces 16 of the elements 1 are machined only partially so as to delimit a central zone 16a projecting from the zones 16b and 16c situated on either side of this zone. Central 16a.

Similarly, the support 3 is subjected to a material removal step between two successive elements of this first series. This removal of material is carried out in a direction substantially perpendicular to that in which the elements 1 extend. In general, these material removals (shown with hatching) are intended to prepare the surfaces of elements 1 already welded which will be in contact and welded with other elements, welded in a second pass.

FIG. 18 illustrates the result obtained after welding of the second series of elements 1 'which are positioned in the spaces formed between the elements 1 of the first series.

As explained previously with regard to the figure

3, these elements are welded to the support 3 by their surface 18 'defined between their bases 11'.

At the end of this second pass, a complete arc 4 is obtained.

Reference is now made to FIGS. 11 and

12 which illustrate the implementation of the method according to the invention on a cylindrical metal support 7.

The method according to the invention is implemented to produce a flange 70 on the periphery 71 of one of these ends.

This flange 70 is here formed using three types of discrete surface elements: elements 1 and 1 which have previously been described, in particular with reference to FIGS. 1 to 4A (represented with hatching), and another type of element 8 which is defined by two substantially flat faces 86 and having the shape of a parallelogram. Each face 86 is defined by two parallel bases 80 and 81 which have the same length L. These two bases 80 and 81 are connected by two pairs of sides 82 and 83 which are parallel and which have a length 1. less than L.

Each pair of sides 82 or 83 defines a side face for an element 8. The method consists firstly in welding an element 8 on the support 7 at the periphery 71.

This first element 8 is welded along its base 80, that is to say along its length L.

As explained above, the method then consists in proceeding to a material removal step to prepare the lateral surface defined between the sides 83 and for the support 7 to have a passage for the material that will escape from the interface between the 8 next element which will be welded on the support, in the counterclockwise direction.

A first series of elements 8 is welded to the support 7, the elements 8 being welded one after the other.

The dimensions of the elements 8 are chosen so that between the first element 8 of the series and the last element 8 welded on the support 7, a space corresponding to the bulk of two elements 1 can be arranged head-to-tail .

The last step of the method consists in welding the element 1 on the first element 8 of the series as well as on the support 7, via its surface 17, defined between its two bases 10; the element 1a on the last element 8 of the series, as well as on the support 7 via its surface 18 'defined between its bases 11' and the two elements 1 and 1 'by their faces 15 and 15' in vis-à-vis.

The flange blank thus obtained may be subject to a subsequent machining step to obtain a metal object. Reference is now made to FIGS. 13 and 14 which illustrate a variant of the method illustrated in FIGS. 11 and 12.

In this variant, the flange 72 is obtained from discrete surface elements, of the type of the element 1 described with reference to the preceding figures.

The method is implemented by first welding on the cylindrical support 7 a first series of elements 1 (represented with hatching) by their face 17 defined between the bases 10, that is to say according to their large size. length L.

They are spaced from each other by a distance corresponding to their short length _1.

As explained above with reference for example to FIGS. 1 to 4A, a material removal step is then performed on both the elements 1 and the support 7.

The method then consists in welding a second series of elements 1 ', both on the support 7 and on the elements 1, the elements being interposed in the spaces formed between the elements 1 of the first series.

Figures 13 and 14 show that the elements 1 and the are arranged head to tail.

Once the second series of elements welded, a flange 70 is obtained.

The blank thus obtained may also be machined to obtain the desired object.

It is understood that depending on the diameter of the cylindrical support 7 and the lengths L and 1, it may be necessary to make the bases 10, 10 '; 11, 11 'and 80, 81 of the elements 1, 1' and 8 slightly concave. In addition, the flanges could also be obtained by producing at least two successive layers.

Advantageously, the metal elements used for the implementation of the process are made of a titanium alloy or a nickel alloy, known to be difficult to machine.

The examples which have been described show that the method according to the invention is particularly well suited to the production of metal object blanks comprising curved or arcuate portions. This is particularly enabled by the use of discrete elements of relatively small thickness and length or, on the contrary, of greater thickness and length.

As is obvious and as also follows from the above, the present invention is not limited to the embodiments more particularly described. On the contrary, it embraces all variants.

Claims

1. A method of additive manufacturing of a blank of a metal object from a digital object, by supplying metallic material on a support itself metal, combined with a supply of energy, characterized in that the the supply of metallic material in the form of a plurality of discrete surface elements (1, 1 ', 2, 8) is carried out, the energy supply making it possible to weld said elements to said support (3, 7) in at least two passes namely a first pass and a second pass, each surface element being defined by a length (L, 1) according to which it is welded to said support, a height (h) according to which it protrudes with respect to said after being welded to it, and a thickness (e) in a plane substantially perpendicular to that defined by the height (h) and the length (L, 1) of the element, the height of the element being greater than its thickness, the method comprising a step of removing dry material of at least one of said elements of the first pass before making the second pass.

2. Method according to claim 1, characterized in that at least one of said elements of the first pass comprising at least one face (14, 15,16, 14 ', 15', 16 ') by which it is intended to be welded to an element of another pass, the material removal step is performed on said at least one face.

3. Method according to claim 2, characterized in that the elements of the first pass are welded to the support (3, 7), spaced apart from each other.

4. Method according to any one of claims 1 to 3, characterized in that the material removal step is of the type assisted by a cryogenic fluid.

5. Method according to claim 4, characterized in that the material removal step is carried out with an addition of liquid nitrogen or CO ₂ .

6. Method according to any one of claims 1 to 5, characterized in that the elements (1, 1 ', 2, 8) are welded successively, a material removal step being performed after the deposition of an element. , for at least a part of said elements.

7. Method according to any one of claims 1 to 5, characterized in that the elements are welded in a first series (1), at least two of which are spaced apart and a second series (1 ') interposed in the space or spaces formed between the elements of the first series, a dry material removal step being provided in said gap or spaces, between the welding of the first series and that of the second series.

8. Method according to any one of claims 1 to 7, characterized in that a material removal step is also performed on the support (3, 7).

9. The method of claim 8, characterized in that this step is performed before the welding of discrete surface elements on the support and consists of delimiting the areas of the support (33, 39) for receiving said elements to achieve an assembly. end to end.

10. The method of claim 8, characterized in that this step is performed between two elements welded successively on the support, in a direction substantially perpendicular to the direction in which said elements extend.

11. Method according to one of claims 1 to 10, characterized in that the welding is carried out without melting.

12. Method according to any one of claims 1 to 11, characterized in that said elements (1, l ', 2) and said support (3) come from the same room.

13. Apparatus for additive manufacturing of a blank of a metal object from a digital object, said device comprising means for welding discrete metallic surface elements on a support itself metal and means for carrying out a removal of material on said elements and / or said support.

14. A method of manufacturing a metal object from a blank obtained by the method according to any one of claims 1 to 12, comprising a step of removing material on the blank to obtain said metal object.

15. A blank of a metal object obtained by the method according to any one of claims 1 to 12.

Metal object obtained by the process according to claim 14.

17. A metallic component of an aircraft obtained by the process according to claim 14.