METHOD FOR ADDITIVE MANUFACTURING AND MACHINE FOR ADDITIVE MANUFACTURING THAT CARRIES OUT THIS METHOD

Description

technical field

[0001] The present invention relates to a method and machine for additive manufacturing by depositing molten filament in successive layers onto a printing substrate in a manufacturing chamber to produce a three-dimensional part. Previous technique

[0002] The advantages of additive manufacturing technologies, also known as 3D printing, are numerous. They allow for the production of highly complex parts, inaccessible through standard manufacturing processes such as material removal (machining, cutting, etc.) or forming (molding, bending, thermoforming, etc.), and all this without additional cost. Overall, regardless of the geometry of the part to be produced, production costs are very low because no expensive tooling is required. All phases of design, development, and industrialization are also simplified. Part modifications can be made indefinitely without impacting production time or costs. In particular, these technologies can be used very early, from the initial design stages. Finally, they allow for the processing of a wide variety of materials, from polymers to metals and ceramics.

[0003] Within companies, these technologies are enabling a complete rethinking of the value chain, from engineering to production. A new phase is emerging in the history of product development and international sourcing strategy. From mass production, industry is now moving towards product customization and production flexibility, significantly increasing the need for small and medium production runs. This explains the high expectations manufacturers have for 3D printing. Indeed, the additive manufacturing market is one of the most promising for the coming years.

[0004] Despite a number of significant advantages, additive manufacturing technologies remain limited in their applications. Historically used for prototyping, they are still not competitive in production compared to standard manufacturing processes for producing large and / or serial parts. Indeed, current technologies primarily lack productivity: manufacturing time is too long, and the resulting parts require time-consuming post-processing for rework and / or adjustment. Furthermore, the accuracy of the resulting parts is relatively low, and fine tolerances are not directly achievable. Ultimately, these technologies only allow for the production of small parts in pre-production or very small batches.To manufacture large parts, defined by a significant volume of material (for example, 1 m³ or more), production time generally requires at least ten hours. Several solutions are currently being developed, but they always involve a compromise between production time and quality, meaning precision. In short, improving one parameter inevitably comes at the expense of the other.

[0005] Among the available technologies, additive manufacturing by filament deposition, known by the acronyms DFF (Fused Filament Fabrication), FFF (Fused Deposition Modeling), FDM (Fused Deposition Modeling), and FGF (Fused Granulated Fabrication or Fusion Granular Fabrication), is the dominant technology in terms of market share and is expected to maintain its leading position in the coming years with significant growth potential. Currently, three technologies are available: Large format additive manufacturing by filament deposition from spool filament; Large format additive manufacturing by pellet-based filament deposition; Large format additive manufacturing by concentrated energy material deposition.

[0006] Fused deposition modeling (FDM) technologies are distinguished by their relatively low production costs. However, they are rarely used in production, primarily due to their poor performance resulting from excessively long printing times. Furthermore, they are unable to produce large parts at high speeds while maintaining the required tolerances. FDM technologies are generally limited to a throughput of 0.3 kg / h. High speed can mean high throughput, i.e., throughputs exceeding 20 kg / h. For example, the travel speed of the extrusion head is considered high when it exceeds 300 mm / s. This is why the available technologies do not allow manufacturers to consider them for production.They remain interesting for meeting R&D, prototyping and research needs but do not allow for mass production in a competitive manner compared to standard processes.

[0007] Several examples of filament deposition technologies are described in publications CN 108 357 091 A, CN 111 633 978 A, CN 110 253 882 B, and EP 3 626 439 A1. However, none of these solutions offers the expected compromise to drastically increase the performance in terms of speed and accuracy of an additive manufacturing process, enabling it to compete with conventional industrial processes. The main reasons are related to the inertia of the material processing unit when it is integrated with the deposition unit, or to the lack of control over the rheology of the molten material throughout its transfer to the deposition unit when the processing unit is located remotely from the deposition unit. Description of the invention

[0008] The present invention aims to fill this gap by proposing a new design of additive manufacturing by molten wire deposition from granules, aiming to radically increase its execution performance, so that it can position itself as an efficient, cost-effective, flexible, responsive, reproducible, and competitive alternative to standard manufacturing processes for producing large parts and / or serial parts in an industrial environment, while guaranteeing compliance with the required manufacturing tolerances in order to minimize the rework operation when it proves necessary.

[0009] To this end, the invention relates to a method of the kind indicated in the preamble, comprising the following steps: a step of supplying at least one raw material, a step of transforming the raw material into molten material in a fixed processing unit located outside said manufacturing chamber, a step of transporting the molten material at its transformation temperature and viscosity in a flexible and heated pipe from said fixed processing unit to a mobile deposition unit located in said manufacturing chamber, and a step of deposition of said molten material in the form of a molten wire in successive layers onto said printing support by said mobile deposition unit until the part to be manufactured is obtained.

[0010] Thanks to this particular configuration of the invention, the speed of movement of the dispensing unit and its movements in space can be much smoother, more responsive, wider, and faster, since they are completely independent of the inertia and size of the processing unit. Indeed, the processing unit is no longer mounted on the dispensing unit as in the prior art, but is located outside the manufacturing chamber and connected to the dispensing unit by a heated flexible hose, which can follow the dispensing unit's movements in space without inertia or constraint.

[0011] Furthermore, the rheology of the molten material is perfectly controlled throughout its transfer from the remote processing unit to the deposition unit, regardless of the heating temperature in the processing unit, the transfer conditions (variations in flow rate and therefore residence time in the pipe, and variable cooling), and heat losses to the external environment (dependent on ambient temperature, atmospheric pressure, airflow in the manufacturing area, etc.). Indeed, the molten material transport pipe is no longer simply thermally insulated, as in previous systems, but heated by energy input via a heating system.In the configuration of the invention and in the absence of a heating system for the transport pipe, the material in transit would solidify in the pipe and form a plug impossible to remove, thus permanently sealing the pipe and making additive manufacturing by molten wire deposition impossible.

[0012] In a preferred embodiment of the invention, said deposition step consists of modifying the cross-section of the molten wire during the manufacture of said part, and of automatically and instantly adapting the printing rate to the required printing accuracy according to the manufactured parts of said part.

[0013] Thus, it is possible to achieve a completely innovative compromise between printing speed and printing quality, making it possible to achieve performance equivalent to, or at least comparable to, conventional industrial manufacturing processes.

[0014] In particular, said deposition step may consist of selecting a large section of molten wire deposited with a high printing rate and low printing accuracy to fill the core of said part to be manufactured, and selecting a small section of molten wire deposited with a low printing rate and high printing accuracy to form contours of said part to be manufactured.

[0015] Furthermore, said deposition step may consist of changing the raw material and / or the geometry of the molten wire during the manufacture of said part, to automatically and instantly adapt the raw material and / or the geometry of the molten wire according to the manufactured parts of said part.

[0016] Preferably, the said deposition step is sequenced to operate the changes in section and / or raw material and / or geometry of the molten wire according to the manufactured parts of said part.

[0017] For this purpose also, the invention relates to a machine of the type indicated in the preamble, comprising: a raw material feeding unit, a transformation unit arranged to change the state of the raw material into molten material, said transformation unit being fixed, located outside said manufacturing chamber, a flexible and heated hose arranged to transport the molten material at its transformation temperature and viscosity from said fixed transformation unit to a mobile deposition unit, a mobile deposition unit located in said manufacturing chamber and comprising at least one deposition nozzle arranged to deposit said molten material in the form of a molten wire in successive layers onto said printing support and along a predetermined trajectory until the part to be manufactured is obtained.

[0018] In a preferred embodiment of the invention, said processing unit comprises at least one screw extruder.

[0019] In addition, the machine may include a control device located downstream of the processing unit, between the processing unit and the heated flexible hose, or preferably between the heated flexible hose and the dispensing unit, and arranged to regulate the flow rate and pressure of the molten material at the outlet of the processing unit or preferably at the inlet of the dispensing unit. The heated flexible hose may be coupled to at least one electrical heating element, arranged around the hose and configured to reach and maintain a set temperature suitable for the molten material being conveyed, without this example being exhaustive.

[0020] In a preferred embodiment of the invention, the dispensing unit comprises a hot block having an inlet orifice connected to the heated flexible hose or the control device, and a rotating disc having at least two dispensing nozzles of different cross-sections, angularly offset. The rotating disc is, in this case, disposed downstream of the hot block and arranged to sequentially align an active dispensing nozzle with an outlet orifice of the hot block, thereby allowing the molten wire to exit.

[0021] Advantageously, said dispensing unit can be tilted relative to the vertical to present the active dispensing nozzle as close as possible to the printing support or the part to be manufactured, and to clear the other dispensing nozzle(s) that are waiting.

[0022] Said dispensing nozzles can be positioned on said rotating disc so that in working position, the axis of the dispensing nozzle which is active is preferably coincident with a vertical.

[0023] In the preferred embodiment, said hot block and said rotating disc can be coupled by a pressure surface contact, and said rotating disc can advantageously form a switch to sequentially open the hot block when a dispensing nozzle is aligned with its outlet orifice and close the hot block when its outlet orifice is located between two dispensing nozzles.

[0024] Said hot block can be mounted in a fixed support block, and can be secured by return mechanisms in the direction of said rotating disc allowing angular displacement of said rotating disc relative to said hot block during a sequential change of the active dispensing nozzle.

[0025] Depending on the embodiment and the part to be manufactured, the aforementioned at least two dispensing nozzles of the rotating disc may be supplied with different raw materials. In this case, at least the aforementioned feeding unit, the aforementioned processing unit, and the aforementioned heated flexible hose are duplicated to supply the said dispensing unit with the aforementioned different raw materials.

[0026] In addition, the said hot block may include an internal shutter arranged to sequentially open and close the said outlet orifice. Brief description of the drawings

[0027] The present invention and its advantages will become more apparent from the following description of several embodiments given by way of non-limiting examples, with reference to the accompanying drawings, in which: there figure 1 is a diagram of the manufacturing process according to the invention, the figure 2is a simplified perspective view of a manufacturing machine according to the invention, the figure 3 is an exploded view of a depositing unit of the manufacturing machine figure 2 , there figure 4 is a top view of the dispensing unit of the figure 3 , there figure 5 is an axial cross-sectional view of the dispensing unit of the figure 4 according to the VV cutting plan, the figure 6 is an enlarged view of detail VI of the dispensing unit of the figure 5 , there figure 7 is an axial cross-sectional view of a material nozzle belonging to the deposition unit of the figure 3 , there figure 8 is an axial cross-sectional view of a hot block of the dispensing unit equipped with a shutter in the closed position, the figure 9 is a view equivalent to the figure 8 showing the shutter in the open position, the Figure 10is a perspective view of a part manufactured according to the additive manufacturing process and machine of the invention, showing its constituent parts, and the figure 11 is a cross-sectional view of the part of the Figure 10 showing its various constituent parts. Description of the implementation methods

[0028] In the illustrated embodiments, identical elements or parts bear the same reference numbers. Furthermore, terms with a relative meaning, such as vertical, horizontal, right, left, front, back, above, below, etc., must be interpreted under normal conditions of use of the invention, and as shown in the figures.

[0029] With reference to the diagram of the figure 1 The manufacturing process according to the invention comprises the following steps: step 1: feeding of a solid raw material MP, step 2: transformation of the solid raw material MP into molten material MF, step 3: transport of the molten material MF, step 4: regulation of the flow of the molten material MF, and step 5: deposition of the molten material MF in the form of a molten wire FF in successive layers along a parameterized trajectory to manufacture a three-dimensional part.

[0030] Steps 3 and 4 can also be reversed as needed.

[0031] In step 1, the manufacturing process feeds a raw material into a feeding unit 11. This raw material, consisting of any type of polymer, composite or not, is suitable for transformation by lowering its viscosity following a temperature increase. Preferably, this raw material is composed entirely or partially of a thermoplastic polymer and may or may not contain any type of reinforcement, additives, and / or adjuvants. The raw material must have a viscosity that stabilizes at a "low" level, increasing its flowability, as soon as it is exposed to a transformation temperature. Conversely, as soon as the exposure temperature is lowered below the transformation temperature, the material's viscosity must return to a "high" level, reducing its flowability. This fluidization capacity facilitates the transfer of the raw material to the deposition step 5.It can be in various forms, such as vitreous or solid elements like fragments, granules, flakes, pellets, tablets, powder, and the like, or as a paste, or even as a non-Newtonian fluid. In the case of vitreous or solid elements, the raw material preferably has a relatively homogeneous particle size suitable for processing step 2. Furthermore, this is the form in which thermoplastic polymers are most widely used and utilized, at a price on average 10 times lower than their equivalent filament in spool form. This raw material can be transferred from the feed unit 11 to a processing unit 12 by any suitable means, whether manual, semi-automatic, or automatic, using standard plastics industry peripherals such as dryers, hoppers, suction systems, silos, etc.

[0032] In step 2, the transformation of the raw material, known as plasticization, consists of a change of state of the solid particles into a more homogeneous, uniform paste-like mass. In the case of a thermoplastic polymer, the input of thermal and mechanical energy leads to a rise in temperature and thus to a fluidization of the material. This plasticization is carried out using a processing unit 12, preferably a rotary screw extruder or any other similar plasticizing device. If it is an extruder, any type of extrusion screw geometry can be used. Screw extrusion technology has the advantage of rapidly reducing the viscosity of the thermoplastic polymer by combining: the temperature increase by heating collars and any input of thermal energy by equivalent means, the shearing between the threads of the screw and the tube of the extruder: the thermoplastic extrusion polymers are shear-thinning, that is to say that their viscosity decreases if the material is sheared, and the pressure increase at the end of the screw: the profile of the screw compresses the polymer, increases the pressure and therefore the temperature of the mixture to melt and mix the material even more efficiently.

[0033] Almost all polymers used in industry are designed to be processed using this extrusion method, which has the advantage of combining all these effects. No equivalent solutions exist other than screw extrusion that offer the same characteristics. Depending on the requirements, the invention can also utilize other types of processing units, such as a heated mixer or similar equipment, even if their performance and / or practicality are lower.

[0034] In the case of an extruder, the rotation of the extrusion screw(s) generates a displacement of material, thus creating a measurable volumetric flow rate. The extruder must be capable of providing a stable output flow rate over time, conforming to a pre-set target flow rate. The use of a screw extruder is therefore preferred because it allows for: A rapid and efficient polymer state change, a simplification of the material change process: simply insert a few purge granules to expel debris from the previous material before introducing the new material. Screw extrusion is thus particularly well-suited to production applications where material changes are frequent and must be very rapid, and above all, without debris from the previous material contaminating the new material. An optimized design of the processing unit 12, since a screw extruder generates an output flow without requiring a pump upstream of the pipe. In the invention, the pipe is directly connected to the extrusion outlet. The processing unit 12 is therefore very compact and simplifies multi-material printing configurations, which would normally require a separate screw extruder for each material.

[0035] The processing unit 12 is advantageously positioned in a fixed location, outside the build chamber 17. The extruder can therefore operate at its maximum capacity and does not negatively impact the movement speed of the deposition unit 16 in step 5, unlike state-of-the-art additive manufacturing machines. Indeed, in state-of-the-art designs, the extruder is positioned within the build chamber, directly coupled to the deposition unit. This necessitates moving a heavy and bulky assembly with very high inertia, limiting the deposition unit's movement speed and freedom of movement. Furthermore, because the extruder is fixed, it can potentially be much larger than state-of-the-art mounted extruders, and thus generate greater extrusion power.Positioning the extruder outside the printing area, i.e., away from the build chamber 17, also simplifies the design of the converting unit 12 and its operation in terms of maintenance, start-up, etc., by making the extruder(s) both easily accessible outside the build chamber 17 and highly modular. Finally, the converting unit 12 can be positioned away from the build chamber 17 without compromising the quality of the molten filament exiting the deposition unit 16, thanks to the flexible, heated transport tube 15.

[0036] In step 3, the molten material is transported from the fixed processing unit 12 to a mobile deposition unit 16 via a flexible hose 15 heated to a specific temperature. This heated flexible hose 15, of a defined length, can be made of several coaxial layers to perform its various functions, such as: flow of the molten material, heating the molten material to maintain it at a given viscosity or to bring it to a given viscosity if it differs from that at the extruder outlet, insulation of the hose from external devices, and control of the flow and temperature of the transported molten material. The structure and constituent layers of the heated flexible hose 15 are determined according to the material to be transported, its corrosive or abrasive nature, and its processing temperature.This flexible 15 hose is heated, for example, by electric heating elements such as heating collars, cables, and / or tapes, placed around the hose carrying the material, thus allowing the set temperature to be reached and stabilized. Using electric heating simplifies the design of the flexible 15 hose in terms of weight, dimensions, sealing, and insulation. Electric heating also allows for better temperature control because the heating elements are very responsive to changes in the set temperature, and it is suitable for certain applications subject to strict health and safety standards, such as in the medical field. Of course, any other heating method for the flexible 15 hose may be suitable depending on the application, such as steam, oil, induction, or similar methods.The pipe is designed to be flexible, allowing a certain range of movement to perform step 5 of removal relative to the fixed and remote transformation unit 12 of said manufacturing chamber 17.

[0037] In step 4, and in order to better control the characteristics of the molten material flow at the inlet of the deposition unit 16, a flow and pressure control device 13 can be provided downstream of the extruder, and preferably downstream of the heated flexible hose 15. This control device 13 may be necessary due to the path of the molten material beyond the extruder, and in particular through the heated flexible hose 15, which transports the molten material in step 3. The longer the path from the processing unit 12 to the deposition unit 16, the higher the pressure the extruder must provide. However, the stability of the extruder's outlet flow rate can be degraded, particularly depending on the rotational speed of the extrusion screw(s). The control device 13 therefore provides an interface between the heated flexible hose 15 and the deposition unit 16, which compensates for this potential flow rate instability.It can consist of a gear pump, also called a polymer pump, or any other equivalent means, which allows the flow rate of the molten material exiting the extruder to be regulated and maintained at a controlled and constant pressure, despite any pressure variations at the extruder outlet. The efficiency of the control device 13 is maximized closest to the point where the molten material is deposited. Therefore, the control device 13 can be mounted on the deposition unit 16.

[0038] In step 5, the deposition of the molten material in the form of molten wire requires a deposition unit 16 arranged to control and calibrate the molten material's output above a printing support 18 in a build chamber 17. The deposition unit 16 is also heated to maintain the molten material at a given viscosity. Furthermore, the deposition unit 16 is mobile and moved within the build chamber 17 relative to the printing support 18 along a pre-parameterized trajectory to build a three-dimensional part layer by layer using the additive manufacturing technique of fused filament deposition. The deposition unit 16 includes at least one deposition nozzle 24 ( figure 3) determining the cross-section of the deposited molten wire in terms of transverse dimension and geometry. The deposition unit 16 can be mounted on a trolley moving in space along 3 or more axes, on a numerically controlled machine or at the end of a multi-axis robotic arm depending on the part to be manufactured.

[0039] There figure 2 This schematically illustrates an example of a manufacturing machine 10 according to the invention. It comprises, in order: a feeding unit 11 in which the solid raw material is stored, for example in the form of granules, a processing unit 12, such as a screw extruder, fed, for example, automatically with solid raw material by the feeding unit 11, to transform it into molten material, a heated flexible hose 15 connected to the outlet of the screw extruder by a conduit 14 via an adapter 19, and to the inlet of the control device 13 to convey the molten material into the build chamber 17, a control device 13 for the flow and pressure of the molten material flow, connected to the outlet of the heated flexible hose 15 and to the inlet of the deposition unit 16, and a movable deposition unit 16 inside the build chamber 17 to deposit the molten material in the form of a molten wire onto a printing support 18 in successive layers until a part to be manufactured is obtained.

[0040] The manufacturing machine 10 of the invention differs from the prior art in that the processing unit 12 is positioned in a fixed location, outside the manufacturing chamber 17 and at a distance from the dispensing unit 16. Thanks to this configuration, the speed of movement of the dispensing unit 16 is not penalized by the mass or size of the processing unit 12, as is the case in the prior art. In addition, the dispensing unit 16 advantageously includes several dispensing nozzles 24 ( figure 3 ) interchangeable almost instantly and automatically during manufacturing. This capability allows the 24-point dispensing nozzle to be modified, thus adapting the printing flow rate and / or the material of the molten filament and / or the cross-section and / or the geometry of the molten filament deposited according to the parts of the part to be manufactured, as explained later.

[0041] Thus, the manufacturing machine 10 can be fed with a single raw material or several raw materials. In the latter case, either the system comprising the feeding unit 11, the processing unit 12, the heated flexible hose 15 and the regulating device 13 is duplicated according to the number of different raw materials and the depositing unit 16 is common with multiple inputs, or the entire feeding unit 11 to the depositing unit 16 is duplicated to have a complete system per material, with several depositing units 16 mounted on the moving part of the machine.

[0042] The dispensing unit 16 is illustrated in more detail in the figures 3 to 9It comprises a hot block 20 through which passes a channel 21 extending between an inlet orifice 22 connected to the heated flexible hose 15 by a sealed fitting (not shown), and an outlet orifice 23 communicating with a dispensing nozzle 24. The dispensing nozzle 24 is mounted on a rotating disk 25. This rotating disk 25 has several dispensing nozzles 24, for example, four dispensing nozzles 24, although this number is not limited. The dispensing nozzles 24 are distributed angularly among themselves, regularly or irregularly, on a circle passing through the outlet orifice 23 of the hot block 20. The dispensing nozzles 24 consist of a body through which passes a straight conduit with axis C, the cross-section of the conduit determining the cross-section of the molten wire exiting it. Each dispensing nozzle 24 is preferably different from the other nozzles in terms of its outlet cross-section, in transverse dimensions and / or geometry.The geometry of the nozzle outlet section can be a circle, rectangle, square, oval, or any other geometric shape, whether or not it is compatible with the printing requirements. The cross-sectional dimensions of the nozzle outlet can be defined by the diameter of a circle, the length and width of a rectangle, the side length of a square, the two cross-sectional dimensions of an oval, or any other cross-sectional dimension of a different geometric shape. Furthermore, the nozzles can be made from various materials, depending on the raw material(s) fed into the manufacturing machine and their abrasive or corrosive properties.

[0043] The dispensing unit 16 includes a support block 26 carrying the hot block 20 along an axis A and the rotating disc 25 along an axis B parallel to the axis A. The hot block 20 is mounted through a bore 27 of the support block 26 by means of a sliding fit at the level of the two guide zones 27a, 27b upper and lower, leaving one degree of freedom in axial translation of said hot block 20. In addition, the hot block 20 is secured in axial translation in the direction of the rotating disc 25 by return members. These return elements are constituted in the example shown, without this example being limiting, by two parallel prestressing screws 28, associated with two compression springs 29. The prestressing screws 28 pass through a collar 30 of the hot block 20 and are screwed into the support block 26. The compression springs 29 extend between the base of the heads of the prestressing screws 28 and said collar 30.In this way, when the preload screws 28 are tightened, they compress the compression springs 29, which then generate a restoring force that increases with their compression. This force is transmitted to the interface between the end of the hot block 20 and the rotating disk 25. The end of the outlet orifice 23 of the hot block 20 is therefore in permanent contact with the corresponding face of the rotating disk 25 through a pressure-bearing surface contact. This mechanical connection via pressure-bearing planar contact has the advantage of ensuring the seal of the interface between the hot block 20 and the rotating disk 25 against the pressurized molten material. It also has the advantage of allowing the rotating disk 25 to move relative to the hot block 20 only during the disk's rotation and without any additional mechanism.The rotating disc 25 then constitutes a simple switching means allowing the hot block 20 to automatically move from a closed position in which it is positioned between two dispensing nozzles 24 and the corresponding solid face of the disc closes its exit orifice 23 interrupting the dispensing of the molten wire, to an open position in which it is aligned on one of the dispensing nozzles 24 and the active dispensing nozzle 24 opens its exit orifice 23 allowing the dispensing of the molten wire.

[0044] In an alternative embodiment (not shown), the sealing of the interface between the outlet 23 of the hot block 20 and the rotating disc 25 can be achieved by a sliding mechanical fit between the two elements, thus inducing permanent surface contact near the dispensing nozzles 24. In this configuration, the hot block 20 can have, at its outlet 23, an enveloping shape that covers the edge of the rotating disc 25 and creates a double bearing surface with the rotating disc 25 so as to be in simultaneous contact with its upper and lower surfaces. This construction ensures controlled axial mechanical clearance at the interface. An alternative configuration can be considered with, conversely, an enveloping shape located on the rotating disc 25, thus containing the interface and the outlet 23 of the hot block 20.These different scenarios make it possible to ensure the sealing of the interface in an advantageous way, by containing the flow of the raw material without inducing contact pressure between the hot block 20 and the rotating disc 25, thereby minimizing friction and limiting the risk of blockage during the rotation of the disc 25.

[0045] The rotating disc 25 is attached to a drive shaft 31, which is mounted for rotation about axis B in a housing 32 of the support block 26 via ball bearings 33 or similar. It is axially locked by a clamping ring 34 or any other locking device. The drive shaft 31 is coupled to an actuator 35, such as a stepper motor, servomotor, rotary actuator, or similar device, to control the angular displacement of the rotating disc 25 about axis B and precisely position the selected active dispensing nozzle 24 opposite the outlet 23 of the hot block 20. The actuator 35 can be fixed to the support block 26 by means of a bracket 36 or any other suitable means.

[0046] In an alternative embodiment not shown, the rotating disc 25 can be provided with a toothed ring, arranged in a plane normal to the transmission shaft 31. The actuator 35 is then not coupled to the transmission shaft 31 but equipped with a toothed wheel driving directly or indirectly the toothed ring itself fixed to the rotating disc 25. In the case where the diameter of the toothed ring is greater than the diameter of the toothed wheel, this advantageously allows the transmitted torque to be maximized, thus limiting possible blockages due to friction at the interface between the rotating disc 25 and the hot block 20.

[0047] In another embodiment not shown, the actuator 35 is anchored on one side to the dispensing unit 16 and acts on the other side on the rotating disc 25 at a point on the latter not coinciding with the axis of rotation B of the transmission shaft 31, allowing, by the application of a tangential force, the generation of a rotational moment actuating the rotating disc 25. In the case where the distance between the point of application and the axis of rotation B is maximal, the transmitted rotational torque is favorably greater, thus limiting possible blockages due to friction at the interface between the rotating disc 25 and the hot block 20.

[0048] In the example shown in the figure 5The dispensing unit 16 is not vertical, but preferably inclined with respect to the vertical, for example at an angle between 0 and 90° (excluding these extreme values), and preferably at 20°, although these values ​​are not limiting. This inclination allows the outlet level of the molten material flow from the active dispensing nozzle 24 to be lowered as close as possible to the printing support 18 or the part being manufactured, and to clear the other dispensing nozzles 24, which are either on standby or passive, at a higher level. Of course, this embodiment is not limiting, and any other variant of a rotating disk, articulated or not, that performs the same function—namely, defining a working position for an active dispensing nozzle at a lower level than the standby positions for the other passive dispensing nozzles—could be suitable.The dispensing nozzles 24 are arranged on the rotating disc 25 such that, in the working position, the axis C of the active dispensing nozzle 24 coincides with a vertical line. Thus, the molten wire exiting the active dispensing nozzle 24 is also vertical and can be deposited precisely at the desired location.

[0049] Each of the 24 dispensing nozzles is temperature-controlled by a heating element (not shown). This could be a resistive heating collar with a thermocouple, a heating cartridge, or any other suitable heating element. Temperature control can be applied individually to each 24 dispensing nozzle, or it can be applied globally to a single target temperature for all nozzles.

[0050] These components can reach temperatures of several hundred degrees Celsius. To minimize heat exchange with other components of the dispensing unit 16, the areas surrounding the dispensing nozzles 24 can be hollowed out to further minimize thermal conduction. Temperature management throughout the dispensing unit 16 is improved by adding axial fans (not shown) advantageously positioned to cool certain areas of the rotating disc 25, the drive shaft 31, or the ball bearings 33, for example.

[0051] The hot block 20 is temperature-regulated by means of a heating element coupled to its outer surface. This can be a resistive heating collar 37, combined with a thermocouple as illustrated in the figure 7or any other suitable heating element. The hot block 20 can reach temperatures of several hundred degrees Celsius. To minimize heat exchange with the other components of the dispensing unit 16, the two guide zones 27a, 27b have small contact areas with the hot block 20. The material recess provided in the areas surrounding the guide zones 27a, 27b further minimizes heat conduction to the other components connected to the dispensing unit 16.

[0052] In a variant represented in the figures 8 and 9 The hot block 20 may include within its internal volume a shutter 38, in order to better control the flow of molten material. This may be a needle valve mounted axially in the hot block 20 and actuated by a mechanism (not shown) between a closed position shown in the figure 8 and an open position represented at the figure 9depending on the manufacturing sequences.

[0053] The support block 26 is the central, structural component of the dispensing unit 16, connecting all the components of the dispensing unit 16. Its lateral faces 39 allow the dispensing unit 16 to be coupled to an external element, for example, a mechanical actuator such as a trolley, a CNC machine, or a robotic arm (not shown), thus enabling the dispensing unit 16 to move. Furthermore, an additional module 40 can be mounted directly onto the support block 26, as illustrated in the Figures 4 and 5 In this case, it may be an additional module 40 interacting with the waiting or passive dispensing nozzles 24, such as a cleaning station or a heating station, these examples not being exhaustive.

[0054] The manufacturing machine 10 according to the invention thus makes it possible to produce a part industrially, regardless of its size, complexity, and / or quantity, by depositing material in a productive and competitive manner. The part to be manufactured is digitized, and software defines the trajectories in space that the deposition unit 16 must follow to build said part as accurately and with the highest possible quality. During digitization, the part to be manufactured is further broken down into different parts to be manufactured according to the required degree of precision, the type of material required, and / or the printing pattern for each constituent part.

[0055] THE Figures 10 and 11 illustrate, as an example, a toothed sprocket 50 to be manufactured. In this example, the toothed sprocket 50 can be broken down into at least three parts having different properties, such as: an outer part 51, called the shell or casing, of thin thickness, which requires both very high manufacturing precision and very high mechanical strength, because it must provide a gearing function with another part and transmit dynamic forces without backlash; a central part 52, called the core, which gives the volume to the part and requires mechanical strength but without high precision because the central bore is intended to mount the pinion on a transmission shaft by keying or other means of fixing; and an intermediate part 53, located between the outer part 51 and the central part 52, of medium thickness, which requires good precision and sufficient mechanical strength to form the teeth of the pinion and support the outer part 51.

[0056] In this example, it is possible to use three dispensing nozzles 24, with a circular outlet section and different diameters, which can be fed by the same raw material, such as: a first nozzle 24 of a very small diameter, for example equal to 0.4mm, which can correspond to the thickness of the wall, associated with a low printing flow rate, for example less than or equal to 1kg / h, allowing to guarantee a very high printing precision, for example a layer height (vertical precision) of about 0.1mm, to form the external part 51 of the part; a depositing nozzle 24 of a medium diameter, for example equal to 1mm, associated with an average printing flow rate of a few kilograms per hour, for example about 3kg / h, for a medium printing precision, for example a layer height of about 0.8mm, and to form the intermediate part 53 of the part;and a large diameter 24 dispensing nozzle, for example 10mm, combined with a very high printing rate of several tens of kilograms per hour, for example around 20kg / h, for low precision, for example a layer height of around 5mm, to form the central part 52 of the part. Of course, these values ​​are given only as an indication and may vary depending on the processing temperatures, the raw materials used, etc...;

[0057] To produce this part, the machine control software sequences the manufacturing process to automatically and instantly change the dispensing nozzle 24 depending on the part being manufactured. To achieve this, the rotating disc 25 is precisely angularly controlled by the actuator 35 to change the active dispensing nozzle 24, which is aligned with the outlet 23 of the hot block 20. This hot block is continuously supplied with pressurized molten material from the processing unit 12 via the heated flexible hose 15 and the regulating device 13. These nozzle dispensing nozzle changes have the advantage of being performed continuously without stopping the machine during the manufacturing process of the part.

[0058] The advantage of working with only one filing unit 16, as opposed to multiple filing units as in prior art, lies in: The simplification and compactness of the dispensing unit 16, which can accommodate, for example, at least four different dispensing nozzles 24 for a single material feed, and the speed of the changeover between two dispensing nozzles 24, which is almost instantaneous (~0.5 sec), are crucial factors since a 1m high part has at least 2000 superimposed layers of material. Therefore, if two different dispensing nozzles are used, this corresponds to a total of 4000 changes in this example. With two separate dispensing nozzles, the changeover time is several seconds (generally between 3 and 5), resulting in downtime of between 3.3 and 5.5 hours for changing the dispensing nozzle for each layer. With the solution of the invention, this downtime is reduced to only 0.5 hours. Furthermore, the repositioning accuracy between two dispensing nozzles is improved, as the machining accuracy in the invention is to the nearest hundredth of a millimeter (+ / -0.01mm).With two separate dispensing nozzles, as in prior art, this precision is either degraded, since conventional motion solutions generally have an accuracy on the order of a tenth of a millimeter (+ / - 0.1 to 0.3 mm), or it results in a significant additional cost to integrate and duplicate highly precise motion solutions. The manufacturing accuracy of the resulting part is therefore directly affected, it being understood that the values ​​given are only indicative.

[0059] The toothed gear 50 is given only as an example to illustrate how it is possible to rethink the manufacturing of industrial parts by breaking them down into sub-parts, in order to optimize and make the most of the additive manufacturing process by fused filament deposition, according to the invention. This process notably makes it possible to reduce printing times by a factor of 100 compared to market leaders, to produce larger parts, for example up to 8 m³, and multi-material parts, for example up to 10 different polymers simultaneously. These polymers can be combined, ranging from conventional to the most technical polymers, the process being flexible, scalable, and intelligent.

[0060] It is clear from this description that the invention achieves the stated objectives and brings additive manufacturing technology and its advantages into industrial production processes, offering a highly flexible and competitive alternative manufacturing solution. It can therefore be easily integrated into the industrial ecosystem, particularly in terms of raw material and connectivity standards. All these elements greatly facilitate the transition of 3D printing technologies from the design office to production units.

[0061] The technical characteristics of the different embodiments and variants mentioned above may be, in whole or in part, combined with each other, without departing from the annexed claims.

Claims

1. An additive manufacturing method by deposition of molten wire in successive layers on a printing support (18) in a manufacturing chamber (17) to manufacture a three-dimensional part, comprising the following steps: - a feeding step (1) of at least one raw material, - a step (2) of processing the raw material into molten material in a fixed processing unit (12) located outside said manufacturing chamber (17), - a step (4) of conveying the molten material at its processing temperature and viscosity in a flexible heating tube (15) from said fixed processing unit (12) to a mobile deposition unit (16) located in said manufacturing chamber (17), and - a step of depositing (5) said molten material in the form of a molten wire in successive layers on said printing support (18) by said mobile deposition unit (16) until the part to be manufactured is obtained.

2. The method according to claim 1, in which said deposition step (5) consists of modifying the section of the molten wire during the manufacture of said part, and automatically and instantaneously adapting the printing rate to the required printing precision as a function of the manufactured parts of said part.

3. The method according to any of claims 1 and 2, wherein said deposition step (5) consists of selecting a large section of molten wire deposited with a high printing rate and low printing precision to fill the core of said part to be manufactured and selecting a small section of molten wire deposited with a low printing rate and high printing precision to form contours of said part to be manufactured.

4. The method according to any of claims 1 to 3, wherein said deposition step (5) consists of changing the molten wire raw material during the manufacture of said part, to adapt the molten wire raw material automatically and instantaneously in accordance with the manufactured parts of said part.

5. The method according to any of claims 1 to 4, wherein said deposition step (5) consists of changing the molten wire geometry during the manufacture of said part, to automatically and instantaneously adapt the molten wire geometry in accordance with the manufactured parts of said part.

6. The method according to any of claims 1 to 5, wherein said deposition step (5) is sequenced to effect changes in section and / or raw material and / or molten wire geometry in accordance with the manufactured parts of said part.

7. An additive manufacturing machine (10) for depositing molten wire in successive layers on a printing support (18) in a manufacturing chamber (17) to manufacture a three-dimensional part, comprising: - a feed unit (11) for a raw material, - a processing unit (12) designed to change the state of the raw material into molten material, said processing unit (12) being fixed and located outside said manufacturing chamber (17), - a flexible heating tube (15) designed to convey molten material at its processing temperature and viscosity from said fixed processing unit (12) to a mobile deposition unit (16), - a mobile deposition unit (16) located in said manufacturing chamber (17) and comprising at least one deposition nozzle (24) designed to deposit said molten material in the form of a molten wire in successive layers on said printing support (18) and along a predetermined trajectory until the part to be manufactured is obtained.

8. The machine according to claim 7, characterized in that said processing unit (12) comprises at least one screw extruder.

9. The machine according to claim 7, characterized in that it comprises a regulating device (13) located downstream of said processing unit (12), between said processing unit (12) and said flexible heating tube (15), or preferably between said flexible heating tube (15) and said deposition unit (16), and designed to regulate the flow rate and pressure of said molten material at the outlet of the processing unit (12), or preferably at the inlet of the deposition unit (16).

10. The machine according to any of claims 7 to 9, characterized in that said flexible heating tube (15) is coupled to at least one electrical resistor, positioned around the tube, and designed to reach and stabilize a setpoint temperature adapted to the molten material being conveyed.

11. The machine according to any of claims 7 to 10, characterized in that said deposition unit (16) comprises a hot block (20) provided with an inlet orifice (22) connected downstream of said flexible heating tube (15), and a rotary disk (25) comprising at least two deposition nozzles (24) of different cross-sections, angularly offset, and in that the rotary disk (25) is located downstream of said hot block (20) and designed to sequentially align an active deposition nozzle (24) with an outlet orifice (23) of said hot block (20) and allow the molten wire to exit.

12. The machine according to claim 11, characterized in that said deposition unit (16) is inclined with respect to the vertical line to bring the active deposition nozzle (24) as close as possible to the print support (18) or the part to be manufactured, and to clear the other deposition nozzle(s) (24) which are on standby.

13. The machine according to any of claims 11 and 12, characterized in that the deposition nozzles (24) are positioned on said rotary disk (25) so that, in the working position, the axis (C) of the active deposition nozzle (24) is aligned with a vertical line.

14. The machine according to any of claims 11 to 13, characterized in that said hot block (20) and said rotary disk (25) are coupled by surface contact under pressure, and in that said rotary disk (25) forms a switch for sequentially opening the hot block (20) when a deposition nozzle (24) is aligned with its outlet orifice (23) and closing the hot block (20) when its outlet orifice (23) is located between two deposition nozzles (24).

15. Machine according to any of claims 11 to 14, characterized in that said hot block (20) is mounted in a fixed support block (26), and is secured by return members (28, 29) in the direction of said rotary disk (25) allowing angular displacement of said rotary disk (25) with respect to said hot block (20) during a sequential changeover of the active deposition nozzle (24).

16. The machine according to any of claims 11 to 15, characterized in that said at least two deposition nozzles (24) of the rotary disk (25) are fed with different raw materials, and in that at least said feed unit (11), said processing unit (12), and said flexible heating tube (15) are duplicated to feed said deposition unit (16) with said different raw materials.

17. The machine according to any of claims 11 to 16, characterized in that said hot block (20) comprises an internal shutter (38) designed to sequentially open and close said outlet orifice (23).