Process and system for resetting the manufacture of additive manufacturing parts

Abstract

The present invention relates to a process for resetting the manufacture of parts generated by additive manufacturing that allows a second part generated on a first part to be bonded on said first part. The parts are bonded by resistive heating with conductive means to which a current that causes said resistive heating is applied. For this purpose, the energy flow to be supplied via the conductive means is determined, the conductive means are placed in at least one of the parts and the ideal temperature for bonding the parts is generated with control means. The invention further relates to a system for resetting the manufacture of additive manufacturing parts that carries out said method, comprising at least conductive means (110) as well as an electrical current control system to obtain the suitable parameters that ensure the quality of the bond.

Description

[0001] DESCRIPTION

[0002] ADDITIVE MANUFACTURING PARTS MANUFACTURING RESTART PROCESS AND SYSTEM

[0003] Technical sector

[0004] The present invention relates to the technical field of additive manufacturing. More specifically, it relates to a manufacturing process and system that allows the generation of a second part using additive manufacturing on a first part made of thermoplastic material.

[0005] State of the art

[0006] Additive manufacturing is a process that offers several significant advantages over other traditional manufacturing methods. These advantages include flexibility in generating geometries, faster manufacturing speed for single parts or small batches, and lower costs as it utilizes additive rather than extractive manufacturing, resulting in savings in raw materials.

[0007] Within additive manufacturing, there is a line of equipment development focused on the design of systems for the manufacture of large components. The use of these systems is beginning to spread, from the fields of tooling and complementary equipment manufacturing to manufacturing processes within sectors such as aeronautics, wind power, and naval, where certain needs exist that the process is capable of meeting. While some critical aspects for the efficient operation of these systems have been resolved—such as the elimination of heated chambers or the generation of systems with variable material deposition widths—there are still significant limitations that prevent further expansion.Additive manufacturing processes for large components involve time-consuming methods and the use of materials with considerable costs. Furthermore, the current robustness of these processes is still insufficient to guarantee a seamless process. Therefore, events may occur that lead to the manufacturing process being halted. This means that the part generated up to that point is no longer valid, typically resulting in its disposal, with the resulting costs and loss of material.

[0008] On the other hand, and related to the previous point, to achieve very large dimensions, there are currently processes that allow the mechanical joining of various components created through additive manufacturing processes. These are usually tedious processes that, when implemented, often lead to higher costs than equivalent products manufactured using traditional methods, which dilutes or eliminates the initial advantages of this type of process. Additionally, there may be sealing or mechanical strength requirements that require material continuity in the joining area. Therefore, a solution is required that allows for agile and efficient joining between components created through additive manufacturing, and even more so, that allows the resumption of manufacturing processes on the part in progress, so that this technology can at least partially overcome current barriers and offer its full benefits to interested sectors.

[0009] There are solutions in the industry for joining thermoplastic-based components through processes such as welding, although their application to additive manufacturing components has been very limited. However, the implementation of these common methods is not sufficient to achieve an acceptable joint between components manufactured by additive manufacturing, as they involve local tempering and joining that do not ensure final part geometry, adequate strength of the joining area, or tightness, among other aspects.

[0010] Object of the invention

[0011] Considering the purpose set forth in the previous section, one aspect of the present invention is a process for restarting the manufacturing of parts generated by additive manufacturing, allowing the continuation of the production of a part that has been interrupted. From that moment on, the process will consist of a first initial part already manufactured and a second part to be manufactured on top of that first part by means of additive manufacturing. The joining of the material layers is facilitated through a process that uses resistive heating with conductive means on the joining surface of the parts, that is, on the surface of the first part where the first layer of the second part is arranged. These conductive means will be connected to an electrical power supply system for the application of a current that causes this resistive heating. The process comprises the following steps.First, the energy flow to be supplied through the conductive means is determined to achieve proper tempering of the bonding surface between a first part and the first layer of a second part. The determination of the energy flow to be supplied through the conductive means and the arrangement of the conductive means will be based on the composition, structure of the conductive means, the geometry of the first manufactured part and the second part to be manufactured, the thermal conductivity of the material to be joined, the rheology of the material, the environmental conditions, and / or other parameters of the materials and the process. The conductive means are then placed in the determined area and arrangement. This arrangement may involve placing them on the bonding surface of the first part to be joined, preferably with said conductive means being fixed to the bonding surface of the first part.

[0012] Preferably, the conductive means are attached to the joining surface of the first part by welding the conductive means to the part's surface, for example, by adding material or directly to the part's base material; by adhesive means; by mechanical means such as clips or positioning elements; or by fitting the conductive means into cavities made for this purpose in the joining surface of the part to be joined.

[0013] Preferably, the fixing stage is implemented automatically through an automated system.

[0014] When the conductive media does not remain on its own on the surface, this fixation allows it to remain stable throughout the process.

[0015] Finally, the conductive means are connected to an electric current supply system, preferably by means of terminals that must be correctly located outside the piece to be accessible (although it is not ruled out that the terminals are embedded inside), and electric current is applied, by means of control means, which preferably control the voltage, intensity and frequency of the electric current, generating resistive heating of the conductive means by Joule effect and the consequent tempering of the joining surface of the first piece.The application of this electric current to the properly positioned conductive media allows the heat generation stage to be carried out in such a way that the temperature across the entire joining surface is homogeneous, avoiding the generation of internal tensions in the material and other undesirable aspects for the subsequent behaviour of the joint arising from non-homogeneous local heating in the joining process, and improving the cohesion, strength and subsequent tightness of the final joint piece in the joining area.

[0016] The second part to be joined is generated by additive manufacturing on the joining surface of the first part using a material application system, such as an extrusion nozzle. This configuration allows for the continuation of an interrupted additive manufacturing process for a part. Manufacturing of the part can be continued by heating the joining surface of the first part and applying new material, also to a temperature that allows the two parts to be joined, until manufacturing is complete.

[0017] Pressure can be applied to this second part generated by additive manufacturing on the first part for proper adhesion by the material application system, such as the extrusion nozzle, with the pressure applied being controlled by the control means. It is also contemplated, but not limited to, that said pressure be applied by pressure rollers connected for this purpose to said material application system, but it could also be applied by other compaction mechanisms such as a mobile tamper.

[0018] This creates a firm bond between the first part and the first layer of the newly manufactured part, allowing for the completion of its manufacturing. The process can be iterative and involve multiple restarts to complete the manufacturing of large parts.

[0019] Preferably, the procedure will be carried out for parts of the same material, although it is also contemplated for parts of different materials. In the latter case, the control means known to the materials will allow the temperature to be reached and maintained for the correct joining between parts.

[0020] According to another feature, to reach the joining temperature, an increasing electrical power supply is applied, gradually raising the temperature to the optimum temperature on the joining surface of the first part for restarting manufacturing, for example, in the form of a ramp. In this way, the heat flow on the joining surface is controlled by means of the intensity applied by the control means to ensure the quality of the joint between the first part and the start of the second part without generating stress, material degradation, or other undesired negative effects.

[0021] In a preferred embodiment of the invention, the conductive means are embedded, inserted or inlaid in the joining surface where they are integrated within the first piece, thus being able to constitute a structural element of reinforcement or additional mechanical resistance.

[0022] Another feature of the process of the invention relates to the fact that it is possible to reinforce the weld between the last layer of the first part and the first layer of the restarted portion of the second part in a subsequent process once the final part has been fully manufactured. To this end, the conductive means installed and embedded in the part allow the joining surface to be reheated by means of resistive heating to improve, if necessary, the interdiffusion of the polymer chains and achieve a higher-quality weld. In this post-welding process, it may be necessary to apply pressure such that the two joining surfaces are pressed together. Preferably, said pressure bringing the two layers together will be achieved through mechanical, pneumatic, or hydraulic systems, or any combination thereof.

[0023] This pressure can be applied manually or automated by means of control means.

[0024] Optionally, and depending on the condition of the bonding surface of the first part or base part, it is envisaged that the bonding surface of the first layer can be conditioned prior to the placement of the conductive means. In this stage of conditioning the bonding surface, actions such as surface machining of the base layer, generation of cavities, recesses or housings to accommodate - at least partially - the conductive means or to facilitate the automatic application process of the conductive means, cleaning of said bonding surface, or the application of conditioning coatings that facilitate or improve the bonding of both parts together, insulating coatings, protective coatings or adhesive agents, can be carried out.

[0025] Preferably, the conditioning of the bonding surface will be carried out by means of an automated process, using numerically controlled machining systems or other automated options for its implementation.

[0026] According to another aspect, the invention also relates to a manufacturing restart system for parts generated by additive manufacturing that performs a process according to the aforementioned characteristics. Said system comprises conductive means, forming a specific electrical circuit by connecting terminals to an electrical power supply system. The system also comprises a regulator of the power supplied to the conductive means for resistive heating thereof such that the appropriate temperature is generated for joining the parts by means of control means. And a material application system for generating the second part by additive manufacturing.

[0027] The conductive means comprise the connection terminals for coupling the power regulator, these connection terminals being in an accessible external position.

[0028] According to another characteristic of the system of the invention, when the second piece is generated by additive manufacturing on the joining surface of the first piece, the system comprises a material application system, such as an extrusion nozzle, and / or pressure application means in the form of a roller, the pressure application means being controlled by the control unit, such that they deposit a successive layer as they move along a determined path.

[0029] Another characteristic of the system is that the conductive media consists of systems of threads, cords, or veils made from materials such as carbon fiber and / or copper wire, allowing for resistive heating and, due to their properties, allowing them to be embedded in the bonding surface.

[0030] Regarding the material of the parts, it is preferably a thermoplastic material. This thermoplastic material may or may not be filled, and if filled, it may preferably be carbon fiber and / or fiberglass, either individually or in combination.

[0031] According to one feature of the invention, the conductive medium would be embedded within the joint, thereby improving its structural performance. Furthermore, as it is a typical composite reinforcement, a joining process is defined that also allows for proper impregnation of said carbon fiber-based conductive media, reinforcing and improving the mechanical response in the joint area.

[0032] According to another characteristic of the additive manufacturing system, the conductive means may comprise electrical insulation; this may comprise all the conductive means or only part of them. This electrical insulation may comprise a veil or fabric or jacket made of a structural material that does not conduct electricity, and it may preferably, but not exclusively, include fiberglass; the insulation may also comprise a non-conductive lacquer. Thus, it can be used for parts made with electrically conductive materials, to prevent dissipation of electricity from the conductive material toward the part or another point in the electrical circuit, which could modify the design parameters and generate, for example, unwanted current peaks. This insulation also makes it possible to eliminate contact problems when using conductive elements connected in parallel.

[0033] Additionally, the system is expected to include temperature sensors connected to the control means so that the ideal temperature is generated and maintained during the joining process of the parts.

[0034] Preferably, for applying pressure, the system comprises at least one pressure tool for actively applying bonding pressure to the first part, and / or at least one tool for applying pressure to the second part once manufacturing is complete, so that their contact surfaces achieve a firm and uniform bond. In particular, the pressure to be applied to the first part can be applied during manufacturing or once manufacturing is complete.

[0035] Preferably, the manufacturing system comprises a subsystem for automatically applying the conductive means to the bonding surface of the part, securing and positioning said conductive means. The subsystem comprises a conductive material unwinding module, a conductive material pulling module, a tempering module, a conductive material cutting module, and / or a conductive material compacting module. The conductive medium is conveyed from the unwinding module to the pulling module, which pulls the conductive material.

[0036] The tempering module allows the temperature of the surface and / or conductive medium to be raised so that the conductive medium can adhere to it, using infrared lamps, lasers, ultrasound or microwave systems, or any other technology that allows reaching the necessary operating temperatures, depending on the specific material of the parts to be manufactured. The tempering process of the conductive medium and / or surface can be carried out before or after the application of the conductive medium, and can be performed continuously or discretely along the surface.

[0037] The cutting module allows the conductive medium supply to be interrupted in the system to cut and restart the process if necessary. The cutting module will preferably be based on mechanical cutting with blades actuated by electronic, pneumatic, or hydraulic systems, although it could also be based on laser cutting systems or other equivalent technologies.

[0038] The compaction module ensures the necessary pressure for proper adhesion in the area where the conductive medium is applied to the part to be joined. In a preferred configuration, the compaction module consists of a compaction roller that also acts as a traction module, although other options, such as mobile rammers, are feasible.

[0039] According to another feature of the system, the subsystem for applying the conductive media incorporates a tension control system for the conductive media, through active means such as rockers or other options, or through passive means such as friction rollers, which allow the tension of the conductive media to be controlled during the application process.

[0040] According to another feature of the system, the conductive media application subsystem incorporates an adhesive or binder application system prior to applying the conductive medium, through spraying, pulverizing, or direct application through a nozzle or similar process. The adhesive or binder will be the material that fixes the conductive medium to the surface, and may or may not require surface tempering for proper operation or curing.

[0041] Preferably, the positioning system is expected to incorporate a series of vision means such as digital scanners that allow the initial evaluation of the surface to be covered, the system being able, in an automated manner, to identify the surface to be covered, define the path to be followed by the conductive medium application system and execute said material application.

[0042] According to an alternative of the invention, the system for applying the conductive medium is supported and moved through the use of an automated system, preferably a robot, although other movement systems such as Cartesian systems or gantry-type configurations are also viable for the implementation of the process.

[0043] It is envisaged that the conductive medium application system may be either integrated into the system for restarting parts generated by additive manufacturing, or arranged independently of it.

[0044] Description of the figures

[0045] The accompanying drawings illustrate, by way of non-limiting example, the manufacturing restart system for additively manufactured parts according to the invention. In said drawings:

[0046] Figure 1 is a block diagram of a preferred embodiment of the present invention.

[0047] Figure 2 is a generic circuit representing a preferred embodiment of a conductive media subsystem connected to a power regulator.

[0048] Figures 3a-ba and 6a-b represent four examples of conductive media subsystems arranged on a first base piece and their corresponding electrical circuits.

[0049] Figure 7 is a block diagram of an embodiment of the conductive means application subsystem. Figure 8 is an exemplary embodiment of the automated conductive means placement subsystem.

[0050] Detailed description of the invention

[0051] A detailed description of the invention will now be given with reference to the figures listed above and according to some non-limiting practical examples of the invention.

[0052] Figure 1 schematically shows a practical embodiment of a system (100) in which a first layer of material of a second piece (200b) is arranged on the joining surface of a first base piece (200a) as it is manufactured or generated, that is, the deposition of material continues to continue the additive manufacturing once the joining temperature of the first piece (200a) has been reached already manufactured. This generation or manufacture of the successive layer (200b) can be produced by any device or apparatus of the extruder or 3D printer type or similar, such as filament, pellet or continuous fiber extrusion, material deposition, material lamination or other options existing in the state of the art; in one of the preferred variants of this embodiment (shown in Figure 2), the device that generates the successive layer (200b) is an extrusion nozzle (140).This device (in this specific case, although not limited to, the nozzle (140)) will comprise displacement means to move over the geometry of the joining surface of the first base piece (200a). While it is moving, a pressure can be applied in a direction perpendicular to the joining surface of the first piece (200a) that can be applied by the nozzle (140) itself or by separate means such as the roller (150) illustrated in said figure.

[0053] Continuing with Figure 1, it also shows conductive means (110) that are arranged on the joining surface of the first base piece (200a) and are fixed to it. In accordance with one embodiment of the invention, a scanner is provided for recognizing said joining surface for the correct arrangement of the conductive means (110). These conductive means (110) are composed of elements provided with a certain electrical resistance that, by Joule effect, when an electric current is passed through them, manage to generate a heat flow to increase their temperature and that of their surroundings. This increase in temperature will be communicated to the first base piece (200a) and, combined with the aforementioned pressure in the direction of the first piece (200a), will produce their union.

[0054] According to a preferred embodiment, a pressure tool (130a) is incorporated which will apply pressure on the first piece (200a) once the second final piece (200b) has been manufactured forming the final piece assembly, and a compensation pressure can be additionally applied on the second piece (200b) by means of a pressure tool not shown in the figures, or only a pressure tool (not shown in the figures) can be incorporated only on the second piece (200b).

[0055] The conductive means (110) also comprise connection terminals (112) for coupling a power regulator (120) (regulation by intensity or voltage or power) that will allow the energy delivered to the conductive means to be adjusted to control its rate of temperature increase and the desired target value of this by means of the control means. The power regulator (120) can be a regulator that has the source that supplies the necessary current or power to be regulated incorporated, or it can be a simple regulator that is connected to a separate suitable source. In addition, the inclusion of sensors to determine the temperature of the pieces (200a, 200b) on the joining surface is planned. The connection terminals (112) are planned to be arranged on the outside of the physical contact or joining interface of the two pieces (200a, 200b), so that they are easily accessible for connection to the regulator (120).

[0056] Figure 2 shows a generic diagram of the conductive means (110) in the form of an electrical circuit connected to the power regulator (120). Each resistive element of the conductive means is represented by an electrical resistance in said circuit and specific examples of physical arrangements of the conductive means on the joining surface of the first base piece (200a) and their corresponding electrical circuits are illustrated in Figures 3 to 6.

[0057] As for the preferred material for electrical conductors, carbon fiber veil or roving is preferred. Roving refers to a strand of continuous fiber filaments. “Veil,” on the other hand, refers to short strands of fiber bundled together. In another embodiment, the conductive media (110) could be or comprise copper wires.

[0058] The material of the parts (200a, 200b) will preferably be a thermoplastic with or without carbon fiber, fiberglass or other fillers.

[0059] According to an alternative of the invention, the conductive element is electrically insulated by means of a veil or fabric made of a non-conductive structural material such as fiberglass, or, in the case of using copper, for example, by means of lacquer. In this way, it can be used for components manufactured with electrically conductive materials, in order to avoid dissipation of electricity from the conductive material towards the parts (200a, 200b) or towards another point of the electrical circuit, which could modify the design parameters and generate, for example, unwanted intensity peaks. This insulation in turn makes it possible to eliminate contact problems in the case of using conductive means (110) connected in parallel.

[0060] According to an alternative of the invention, the system (100) for restarting additive manufacturing parts comprises a subsystem for automatically placing and fixing the conductive means (110) to the part (200a, 200b), in order to dispense with the need for an operator in the procedures in which it is viable. Thus, according to a practical embodiment of the invention, as can be seen in Figure 8, said subsystem (300) comprises an unwinding module (310), a traction module (320), a tempering module (330), a cutting module (340) and a compaction module (350) of the conductive material of the conductive means (110).

[0061] According to the block diagram in Figure 7, the subsystem (300) scans the surface, and the control means of the subsystem (300) according to the information received send a signal to the unwinding module (310) for the supply of conductive material by means of a traction module (320). Preferably, for this objective, the subsystem (300) comprises vision means such as digital scanners that allow the initial evaluation of the surface to be covered, the system being able, in an automated manner, to identify the surface to be covered, define the path to be followed by the conductive medium application system and execute said material application.

[0062] Subsequently, before its application, a tempering module (330) raises the temperature of the surface of the piece (200a, 200b) and / or of the conductive medium through infrared lamps, lasers, ultrasound or microwave systems, or any other technology that allows reaching the necessary operating temperatures depending on the specific material of the pieces to be joined. Next, a compaction module (350) ensures the necessary pressure so that the adhesion is carried out correctly in the application area of ​​the conductive medium (110) on the piece (200a, 200b) to be joined. Preferably, the compaction module comprises a compacting roller that also performs the functions of a traction module, although other options such as mobile rammers are feasible.

[0063] Finally, a cutting module (340) allows the supply of the conductive medium (110) to be interrupted in order to cut and restart the process if necessary. The cutting module (340) comprises blades actuated by electronic, pneumatic or hydraulic systems, although it could also be based on laser cutting systems or other equivalent technologies.

[0064] According to a design option, the subsystem (300) comprises a tension control system (360) of the conductive medium, through active means such as rockers or other options, or through passive means such as friction rollers, which allow controlling the tension of the conductive media in the application process thereof.

[0065] Furthermore, it is contemplated that the subsystem (300) may be both integrated into the system (100) for restarting parts generated by additive manufacturing, and may be arranged independently of it.

Claims

CLAIMS 1. Process of restarting the manufacturing of parts generated by additive manufacturing, applying resistive heating to said parts with conductive media (110), which comprises the following stages: - determine the energy flow to be supplied through the conducting media (110), - arranging the conductive means (110) on the joining surface of a first piece (200a) manually or automatically, - applying an electric current by means of control means to the conductive means (110) so that they generate heat by Joule effect, reaching a temperature suitable for joining the first piece (200a) and a second piece (200b), - applying a first layer of material of the second part (200b) on the tempered joining surface of the first part (200a), by means of an additive manufacturing system, so that it is joined to the joining surface of the first part (200a), - apply successive layers of material after the first layer of material of the second piece (200b) until the manufacturing is complete.

2. Process for restarting the manufacturing of parts generated by additive manufacturing according to the previous claim, in which the conductive means (110) are embedded between the joining surface of the first part (200a) and the second part (200b), forming part of the finished product or part.

3. Process for restarting the manufacturing of parts generated by additive manufacturing according to any of the preceding claims, in which the heat generation stage is carried out by progressively raising the temperature to the joining temperature between the first part (200a) and the second part (200b).

4. Process for restarting the manufacturing of parts generated by additive manufacturing according to any of the preceding claims, wherein the heat generation step is carried out such that the temperature across the entire joining surface is homogeneous.

5. Process for restarting the manufacturing of parts generated by additive manufacturing according to any of the preceding claims, comprising a step of applying pressure to join the first part (200a) and the second part. (200b).

6. Manufacturing restart process for parts generated by additive manufacturing according to claim 5, in which the application of pressure for the union between the first part (200a) and the second part (200b) is carried out by the material application system.

7. Process for restarting the manufacturing of parts generated by additive manufacturing according to any one of the preceding claims, comprising a step of applying pressure and temperature to the joining area after the end of manufacturing, said pressure being applied through mechanical, pneumatic or hydraulic means or any combination of the above controlled by the control means.

8. Process for restarting the manufacturing of parts generated by additive manufacturing according to any of the preceding claims, comprising a prior stage of conditioning the bonding surface of the first part (200a).

9. System (100) for restarting the manufacturing of parts generated by additive manufacturing, applying resistive heating to said parts according to a method according to any one of the preceding claims, comprising conductive means (110) with terminals (112) for connection to an electrical power supply system, a regulator (120) of power supplied to the conductive means (110), with a material application system for the generation by additive manufacturing of the second part (200b), and with control means for regulating the power so that the appropriate temperature is generated for the union of the first part (200a) with the first layer of the second part (200b).

10. System according to claim 9, comprising pressure application means on the first layer of material of the second part (200b) arranged in the material application system and / or pressure application means in the form of a roller (150), said pressure application means being controlled by the control unit.

11. System (100) according to claims 9 and 10, comprising at least one pressure tool (130a) for applying bonding pressure to the first part (200a), and / or a pressure tool for applying pressure to the second part (200b) once manufacturing is complete.

12. System (100) according to any one of claims 9 to 11, comprising a subsystem (300) for applying the conductive means (110) automatically, comprising a conductive material unwinding module (310), a conductive material traction module (320), a tempering module (330), a conductive material cutting module (340) and / or a conductive material compaction module (350).

13. System (100) according to the preceding claim, wherein the subsystem (300) comprises a tension control module (360) for active or passive tension control of the conductive material.

14. System (100) according to the previous claim, wherein the subsystem (300) comprises a system for applying adhesive or binder prior to the application of the conductive medium (110).

15. System (100) according to the previous claim, wherein the subsystem (300) comprises vision means configured to evaluate the surface of the first piece (200a) to be covered.

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