3D printing device including in situ radiation treatment around the heat-activated material supply head

Abstract

The present invention relates to a system for depositing a heat-activatable material on a receiving substrate comprising a device for preparing a heat-activatable material having a supply head movable along several axes relative to a support of the receiving substrate, a heating means orientable towards a first point of the deposit zone of said heat-activatable material on said receiving substrate and a contactless thermal measuring device providing a thermal image of a first part of the deposit zone of said heat-activatable material. Characterized in that it comprises: at least one second heating means orientable towards a second point of the deposit zone of said heat-activatable material. Said system comprising a computer for controlling a first orientation of said first heating means and a second orientation of said second heating means and for controlling the activation,the modulation of energy flow and / or the deactivation of each of said heating means. Figure 1,

Description

Title of the invention: 3D printing device including in situ radiation treatment around the head for supplying thermoactivatable material Field of the invention

[0001] The present invention relates to the field of additive manufacturing (3D printing) making it possible to create volume parts by adding material by beads of fusible material through a nozzle movable relative to a printing support.

[0002] Printer nozzles generally move along 3 axes (3 spatial translations: width (X), depth (Y), height (Z). Some 3D printers, particularly robotic ones, add 2 rotations to the nozzle head (A and B) facilitating the design of the supports required for certain parts.

[0003] 3D printing of heat-activated materials may require that layers fuse to create a strong, void-free structure. The quality of the resulting structure is generally determined by the integrity of the bond between the printed layers. It is desirable that materials in adjacent layers fuse completely, so that the resulting structure has the same physical strength and mechanical properties as the underlying material. If the bond between layers is incomplete, the layer-to-layer bond may exhibit flaws and brittleness that degrade the ultimate physical strength of the resulting structure.

[0004] In general, each heat-activatable material has an optimal temperature range and a bond with the underlying material which is itself at a temperature resulting from its previous heat treatments and its local thermal inertia: when an area is printed, it begins to cool. The cooling rate depends on several factors, including the material itself, the temperature of the material during printing, the temperature of the underlying layer, the temperature of the environment in which the part is printed and the physical shape of the component to be printed. These different parameters are constantly changing, and it is very difficult to control additive printing under optimal conditions ensuring appropriate thermal conditions at all times, regardless of the shape of the part to be manufactured.

[0005] It is known to carry out real-time acquisition of the local temperature using a thermographic camera. This allows the operator to visually monitor the overall temperature of the part during its printing and to adjust the temperature of the heat-activatable material at the nozzle outlet and / or the nozzle movement speed.

[0006] In the context of this patent, the term "heat-activatable material" will be used to designate a material whose state changes depending on the temperature, for example a thermofusible material, a thermo-reactive material, a thermoplastic material, a thermosensitive material, etc.

[0007] The term "delivery head" will mean any means which brings the heat-activatable material into a local area, for example and without this being restrictive by projection, or extrusion or any other method of depositing materials. State of the art

[0008] Known in the prior art is patent application EP4056351 describing an additive manufacturing apparatus, comprising an extruder configured to receive a thermoplastic material and an applicator assembly downstream of the extruder. The applicator assembly comprises a nozzle for depositing the thermoplastic material in the form of a plurality of layers, a temperature sensor configured to detect a temperature of at least a portion of a deposited layer. A positioning assembly is configured to modify an angular position of the temperature sensor; and a controller is configured to receive temperature signals from the temperature sensor, compare the detected temperature to a previously detected temperature, modify a movement speed of the applicator assembly when the detected temperature is lower than the previously detected temperature by a first temperature difference.The second temperature signal is ignored when the second temperature is lower than the previously detected second temperature by a second temperature difference that is greater than the first temperature difference.

[0009] US Patent 10265911 describes an image-based monitoring and feedback system for three-dimensional printing. A camera captures images of objects being printed and an image processing system compares the images with reference images to detect and correct differences between the object and the reference. The correction may be in real time or applied to a subsequent print. Other aspects include a calibration system that prints predefined test objects and compares them to references to ensure that the printer's operating parameters are correctly set. The comparison may be performed manually by a user or automated as part of the image processing system.

[0010] Patent application WO2023086250 describes a method for 3D printing a part with an additive manufacturing system which consists of printing a first part of a part in layers and analyzing a topology of the first part of the part. The method consists of determining a toolpath for printing a second part of the part on a surface of the first part of the part, and preheating the first part of the part along the toolpath based on the topological analysis of the first part of the part. The method involves printing the second part of the part along the toolpath.

[0011] Application EP3500417 proposes a multi-axis robotic additive manufacturing system, comprising a robotic arm movable according to six degrees of freedom;

[0012] a build platform movable in at least two degrees of freedom and independent of the movement of the robotic arm for positioning the part being built to counteract the effects of gravity based on the geometry of the part. An extruder is mounted at one end of the robotic arm and configured to extrude at least a portion of the material with a plurality of flow rates, wherein the movement of the robotic arm and the build platform is synchronized with the flow rate of the extruded material to build the 3D part. Alternatively, a preheater, for example a laser beam, is configured to locally preheat a portion of the previously printed portion of the part along a tool path prior to extrusion of the material along the tool path by the extruder.

[0013] Patent FR3126633 describes an additive manufacturing method consisting of controlling the movement on the surface of a part of equipment comprising at least one laser whose beam is focused on the output of a feed head delivering at least one metal wire of a diameter D. This equipment is controlled to move the zone of interaction of the laser beam with at least one wire along a main trajectory representative of the geometry of the part to be manufactured.The movement of the interaction zone is modulated by a 2-axis scan in a longitudinal direction parallel to the speed vector of said main trajectory and a transverse direction, normal to the speed vector in the focal plane, said deviation defining a swept curve with a speed greater than the speed of movement along said main trajectory, said 2-axis scan being controlled by a control system comprising means for parameterizing for each production the control law of said 2-axis scan.

[0014] Patent US9095928B2 relates to a system and method for use in brazing, coating, buildup, filling, matting, welding, and joining applications. Said system includes a first laser beam system that directs a first laser beam onto a surface of at least one workpiece to create a molten pool on the surface, and a wire feeder that advances a non-durable article to the molten pool such that the non-durable article contacts the molten pool. The system also includes a power supply that outputs a heating signal, and the heating signal is directed onto the non-durable article to heat the non-durable article before the non-durable article enters the bath. The system further includes a second laser beam system that directs a second laser beam at the non-durable article before the non-durable article enters the bath, and a controller that controls an output of the power supply and the second laser beam system. Disadvantages of the prior art

[0015] The solutions of the prior art are not entirely satisfactory because they do not allow all thermal artifacts to be processed around the extruded bead deposition area. Indeed, the extrusion head or filler head partially masks the optical field of the thermal camera or of a heating laser, leaving certain points poorly controlled from a thermal point of view or requiring a rotation that is not very responsive to the entire heating device or even to the filler head itself and / or requiring multiple continuous printing revolutions that are not very compatible with cable routing, for example. Solution provided by the invention

[0016] In order to overcome these drawbacks, the present invention relates in particular to a system for depositing a heat-activatable material on a receiving substrate comprising a device for preparing a heat-activatable material having a supply head movable along several axes relative to a support of the receiving substrate, a heating means orientable in the direction of a first point of the deposit zone of said heat-activatable material on said receiving substrate and a non-contact thermal measurement device providing a thermal image of a first part of the deposit zone of said heat-activatable material

[0017] Characterized in that it comprises: - at least one second heating means orientable towards a second point in the area of ​​deposit of said heat-activatable material - Said system comprising a computer for controlling a first orientation of said first heating means and a second orientation of said second heating means and for controlling the activation, modulation of energy flow and / or deactivation of each of said heating means.

[0018] The non-contact thermal measuring device may be composed of one or more cameras to cover the deposit area.

[0019] The camera perception area is not necessarily the same as the drop-off area.

[0020] Advantageously, said two heating means are arranged on either side of said device for preparing a heat-activatable material.

[0021] According to a variant, the deposition system further comprises an additional non-contact thermal measuring device providing a second thermal image of a second part of the deposit zone of said heat-activatable material, complementary to said first part with respect to the supply head,

[0022] According to one variant, at least one of said heating means consists of a laser or a focused radiant lamp.

[0023] Advantageously, said heating means consist of a single laser, a beam splitter and two galvanometric mirror scanning systems.

[0024] According to another variant, said heating means consist of a single laser and an optical fiber arranged around the supply head, and having a plurality of outputs.

[0025] According to a particular embodiment, the system further comprises a camera providing a textured image of said area of ​​deposit of said heat-activatable material.

[0026] Detailed description of a non-limiting example of embodiment

[0027] The present invention will be better understood on reading the following description, concerning non-limiting examples of embodiment illustrated by the appended drawings where:

[0028] [Fig-1] [Fig.l] represents a schematic view of a first example of a system according to the invention

[0029] [Fig.2] [Fig.2] represents a schematic view of a second example of a system according to the invention

[0030] [Fig.3] [Fig.3] represents a schematic view of a third example of a system according to the invention

[0031] [Fig.4] [Fig.4] represents a schematic view of a fourth example of a system according to the invention. General principles of the invention

[0032] The system according to the invention comprises, in a known manner, a device for preparing the heat-activatable material (10), for example an extruder, comprising a supply head (11) delivering a bead of heat-activatable material along a trajectory defined by the relative movement of the supply head (11) with respect to the support (20) of the printing substrate. The installation comprises two infrared cameras (31, 32) arranged on either side of the extruder (10) so as to acquire two planes or zones respectively (41, 42) slightly overlapping at the outlet of the supply head (11).

[0033] More generally, any type of non-contact thermal measuring device can be used, a thermal camera being a simple example of such a device.

[0034] Preferably, the two infrared cameras (31, 32) are arranged symmetrically with respect to the longitudinal axis of the extruder (10), on a transverse axis corresponding to the instantaneous direction of the relative movement of the extruder (10) with respect to the support (20), so that the optical field respectively (51, 52) of each of the infrared cameras (31, 32) includes the point of deposit of the thermoactivatable material by the supply head (11).

[0035] This configuration makes it possible to acquire two thermal images with an overlap, and to construct a dynamic map of the temperatures of the zone of deposition of the thermoactivatable material by the supply head (11), as well as of the surfaces upstream and downstream of this zone.

[0036] The system also comprises two heating means formed by two lasers or by a single laser (1) associated with a beam splitter (2) and two galvanometric mirror scanning systems (3, 4).

[0037] These heating means are controlled on the one hand to activate or deactivate the two beams, and to direct them in a direction close to the zone of deposit of the heat-activatable material by the supply head (11), in particular upstream of the zone of deposit of the heat-activatable material for one of the beams and downstream of the zone of deposit of the bead of heat-activatable material for the other beam.

[0038] Actuators (5, 6; 7, 8) controlled by a computer control the orientation and wobbling of the corresponding beams, i.e. a scan of low excursion in lateral and / or longitudinal directions relative to the axis of the segment of the bead upstream or downstream of the zone of deposition of the bead of heat-activatable material to modulate the surface and the heating temperature. Operating principle

[0039] The aim of the invention is to enable the temperature of the substrate upstream of the deposition of a bead of heat-activatable material and / or the temperature of the bead deposited downstream to be adjusted in real time and dynamically.

[0040] In order to be able to cover 360° around the feed head (11), the heating source (1) is cut into at least two, so that the partial heat treatment zones (26) and (27) illustrated in [Fig. 2] are complementary and their union is continuous around said feed head. Thus, the routing of the heating source as required to an area upstream of the depositing point or an area downstream of the depositing point. These two zones have an overlap (intersection between the partial zones (26) and (27) in the case of a cut in two).

[0041] In the description, the use of the term “extruder” must be understood as designating a non-limiting example, any other means of preparing the material to be deposited being able to be used in the invention.

[0042] Heat sources allow: - to add a heat flow just before depositing the new material input (filament, etc.) to promote inter-layer cohesion - control the post-deposition cooling of the new deposit to promote coalescence and spreading of the material in the molten state on the substrate - adjust the crystallization times of the material concerned by the phenomenon

[0043] This solution also makes it possible to avoid heating the environment or to reduce its heating, and to compensate for a lower ambient temperature by local heating (energy saving benefit, elimination of a global thermal enclosure). Thermal mapping of the entire deposit area including the upstream and downstream parts makes it possible to control the heating means in real time.

[0044] Positioning of the laser and cameras relative to the feed head

[0045] The radiative heat sources of the laser type, without being limiting, are arranged on either side of the device for preparing the thermoactivatable material, in a fixed manner, or with the possibility of rotation relative to the longitudinal axis of the device for preparing the thermoactivatable material, with an amplitude less than or equal to 360°.

[0046] Each of the scanning beams is controlled by a computer to determine its main orientation and its wobbling trajectory, relative to the main direction of the trajectory for depositing the heat-activatable bead; as well as its activation, its thermal flux modulation or its deactivation.

[0047] This makes it possible to assign one of the beams to a function of preheating the area of ​​the substrate upstream of the bead deposit point and / or another beam to a function of controlling the cooling of the bead which has just been deposited, downstream of the bead deposit area. This also makes it possible to reverse the function assigned to each of the beams according to the orientation of the main direction of the deposit trajectory, to avoid masking by the supply head (11).

[0048] When the system uses two cameras (31, 32), they can be kept fixed in the same frame of reference as the removal device, or mobile in rotation relative to the longitudinal axis of the removal device, with an angular travel limited to 360°, to cover the entire area of ​​interest thanks to the partial overlap of the fields of the cameras [Fig.l] (41, 42). Control context illustrated by Figure 1

[0049] In this first operating mode, the first source beam (12) is active, and oriented and modulated by the scanning system (4) in a direction upstream of the point of deposit of the heat-activatable material in order to ensure preheating of the substrate.

[0050] In the example, the laser (1), fixed in the reference of the supply head (11), ensures the function of preheating the substrate upstream of the deposition. The guidance of the beam (22) is ensured by galvano mirrors (17, 18) and can point or scan the substrate on the Deposition trajectory. The power and frequency of the upstream laser beam (22) are controlled in a closed loop or by a specific algorithm according to the thermal setpoint to be achieved and the temperatures of the Substrate read by the IR camera device (31 32). In the case where the substrate to be preheated is on the other side, then the beam (23) would be directed towards this area. The pre-heating zone is controlled in a closed loop by the 360° measurements of the IR cameras and located on the area of ​​the substrate close to the point of deposition of the heat-activatable bead.

[0051] Advantages: The system is responsive and fast because there is no need to rotate the laser (1) and / or the effector carrying the extruder (10) to point at the local area to be heated. A single laser (1) is capable of providing a function (here pre-heating) on ​​either side of the feed head (11). Advantageously, the beam which provides the pre-heating function will treat the substrate close to the feed head in order to limit thermal losses between the exit from the treatment zone and the start of actual deposition of thermo-activatable material. Command context illustrated by Figure 2

[0052] In order to be able to cover 360° around the deposition nozzle (11), a laser source (1) is cut out in order to route local heating to enlarged areas of the substrate (26, 27) as required. The areas (26, 27) have an overlap.

[0053] The second laser beam (13), fixed in the reference of the supply head, is active and ensures the “cooling control” function in zone (27). The guidance of the beam (23) is ensured by galvano mirrors (8, 18) and can point or scan the Substrate on its trajectory. The power and frequency of the beam (23) are controlled in a closed loop or by a specific algorithm according to the thermal setpoint to be achieved and the thermal measurements of the IR camera device.

[0054] In the case where the substrate to be preheated is in Zone (26), then the beam (22) would be directed towards this zone, the state of the laser beam splitter (2) then being reversed.

[0055] The “pre-heating” function illustrated by the operating mode of [Fig.l] is essential for the quality of the interface / welding.

[0056] The function illustrated by [Fig.2] makes it possible to adapt the cooling profile over a larger scanning area; the ambient temperature and the effective temperature of the newly deposited rope are involved in setting the parameters of the scanning laser beam.

[0057] Advantageously, the configurations of [Fig.l] and [Fig.2] respectively ensuring the functions of “pre-heating” and “cooling control” can coexist around the supply head (11) in order to simultaneously fulfill these two functions and this at 360° around the supply head. Command context illustrated by Figure 3

[0058] The two IR cameras (31, 32) provide thermal reading of the zones (41, 42) to provide information to the computer controlling the actuators (4 to 8) of the galvano mirrors (7, 17; 8, 18) to add a thermal flux to the substrate on the future deposition trajectory with a laser control loop using the thermal measurements. Command context illustrated by Figure 4

[0059] In this example, the system comprises a laser (1) dedicated to preheating and a laser (5) dedicated to controlling cooling downstream.

[0060] The device provides for ensuring both the “pre-heating” Function (upstream) and Function 2 of “cooling control downstream”.

[0061] For this, the supply head (11) can be rotated around its axis so that the zone (26) intended for pre-heating actually points at the substrate regardless of the deposition trajectory. An infrared camera (31) locally measures the temperature of the substrate slightly before the zone (26) of the laser treatment as well as the heating that it generates in order to carry out closed-loop regulation.

[0062] The area (36) can be more restricted because it is located close to the deposition point. A high frequency camera is desirable. Galvano mirrors are an option to perform a specific scan on the substrate.

[0063] Downstream, the zone (42) is wider because the portion of the new deposit being cooled is longer and more sinuous. As the filler head rotates on itself, galvano mirrors are necessary so that the Cooling Control Function Laser adapts to the change in orientation of the head and the complex shape to be treated.

Claims

Claims

1. - System for depositing a heat-activatable material on a receiving substrate comprising a device for preparing a heat-activatable material having a supply head (11) movable along several axes relative to a support of the receiving substrate (26, 27), a heating means (1) orientable towards a first point of the deposit zone of said bead on said receiving substrate (26, 27) and a thermal measuring device (31, 32), without contact, providing a thermal image of a first part of the deposit zone of said heat-activatable material Characterized in that it comprises: - at least one second heating means orientable towards a second point of the deposit zone of said heat-activatable material - Said system comprising a computer for controlling a first orientation of said first heating means and a second orientation of said second heating means (31, 32) and for controlling the activation,the modulation of energy flow and / or the deactivation of each of said heating means (31,32),.,

2. - System for depositing a heat-activatable material on a receiving substrate according to claim 1 characterized in that said two heating means are arranged on either side of said device for preparing a heat-activatable material.

3. - System for depositing a heat-activatable material on a receiving substrate according to claim 1 characterized in that it further comprises an additional contactless thermal measuring device providing a second thermal image of a second part of the deposit zone of said heat-activatable material, complementary to said first part with respect to the supply head (11),

4. - System for depositing a thermoactivatable material on a receiving substrate according to claim 1 characterized in that at least one of said heating means consists of a laser or a focused radiant lamp.

5. - System for depositing a thermoactivatable material on a receiving substrate according to claim 1 characterized in that said heating means consist of a single laser, a beam splitter (2) and two galvanometric mirror scanning systems.

6. - System for depositing a thermoactivatable material on a receiving substrate according to claim 1 characterized in that said heating means consist of a single laser and an optical fiber arranged around the supply head (11), and having a plurality of outputs.

7. - System for depositing a heat-activatable material on a receiving substrate according to claim 1, characterized in that it further comprises a camera providing a textured image of said deposit area of ​​said heat-activatable material.

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