Method for manufacturing an inductor and associated inductor

Abstract

Method for manufacturing an inductor and associated inductor. Method for manufacturing an inductor (25) for the surface treatment of a mechanical part (1), comprising the steps of: - making a preform (9) adapted to follow an external contour (3) of the part (1), according to an additive manufacturing method, having an internal surface (11) facing the external contour (3), - deposition on the preform (9) of a thin layer (13) of a first metal, according to a chemical reduction method by spraying, - deposition of a first layer (15) of a second metal, over the thin layer, according to an electrolytic method, - placement of at least one first elongated sensor (17) extending over the first layer (15), facing the internal surface (11) of the preform (9), - deposition of a second layer (19) of the second metal, over the first layer (15), and - destruction of the preform (9) and obtaining the inductor (25). Figure to be published with the abbreviation: 7

Description

Title of the invention: Method for manufacturing an inductor and associated inductor Technical field of the invention

[0001] The invention relates to a method for manufacturing an inductor for the heat treatment of a mechanical part. The invention also relates to an inductor obtained by implementing this manufacturing method. Prior art

[0002] Gear-type power transmission parts are often heat-treated to harden their surface, particularly to meet dimensional requirements.

[0003] The use of induction heat treatment instead of thermochemical treatments offers several advantages: speed of execution, repeatability, good fatigue performance of the treated parts, and better compliance with environmental requirements.

[0004] Such a process is implemented by placing a conductive structure, called an inductor, in contact with the part, and by generating a magnetic field in the part by means of said inductor connected to a generator.

[0005] However, induction heating of complex geometry parts such as gears reveals other problems, such as controlling heating profiles and homogeneity of treatment in the functional areas of the part.

[0006] Process conformity is directly related to the interaction between the magnetic field generated by the inductor and the workpiece. Therefore, in addition to optimizing the electrical parameters, designing the correct shape for the inductor relative to the requirement and ensuring its manufacturability are key points for developing the process.

[0007] Thus, it is desirable to be able to manufacture inductors that precisely conform to the contours of the parts, in order to improve the homogeneity of the treatment on the surfaces of said parts. Such inductors are sometimes difficult to manufacture and require weld or braze points, which constitute areas of weakness in the inductor and generate significant losses in performance and efficiency.

[0008] From an industrial perspective, controlling the reproducibility of the treatment from one part to another under identical conditions (identical process parameters) is made more complicated by inductor wear, variations in cooling efficiency over time, and small variations in the relative positioning of the inductor and the part, which can lead to significant field variations. magnetic.

[0009] Furthermore, conformity control is carried out on parts at an advanced stage of the manufacturing process and deviations are only detected after the production of a significant quantity of non-conforming parts. Presentation of the invention

[0010] The invention aims to overcome these drawbacks by proposing a method for preparing an inductor suitable for the heat treatment of parts with complex geometries, without presenting any weak points. The resulting inductor also allows for better control of the part hardening process.

[0011] To this end, the invention relates to a method for manufacturing an inductor for the heat treatment of a mechanical part, the method comprising the following steps:

[0012] - production of a preform adapted to follow an external contour of the part, according to an additive manufacturing method, where the preform has an internal surface facing the external contour of the part.

[0013] - deposition on the preform of a thin layer of a first metal, according to a method by chemical reduction via spraying,

[0014] - deposition of a first layer of a second metal, over the thin layer, according to an electrolytic method,

[0015] - installation of at least one first elongated sensor extending over the first layer, facing the internal surface of the preform,

[0016] - deposition of a second layer of the second metal, on top of the first layer and at least part of the first elongated sensor, and

[0017] - destruction of the preform and obtaining the inductor.

[0018] Such a process makes it possible to manufacture a complex-shaped inductor without weak points, thanks to the combination of additive manufacturing and electroforming. Furthermore, it allows for the simple integration of at least one elongated sensor, enabling continuous and localized monitoring of temperature variations in the inductor and the workpiece being processed.

[0019] The first sensor is arranged in particular to control the efficiency of the cooling during the use of the inductor.

[0020] The process may include, after the step of depositing the second layer of the second metal, the following steps:

[0021] - placement of at least one second elongated sensor on the second layer, facing the internal surface of the preform, and

[0022] - deposition of a third layer of the second metal, on top of the second layer and at least part of the second elongated sensor.

[0023] The second elongated sensor is arranged to measure the processing temperature of the room via the heat irradiated by the room and perceived by the inductor.

[0024] The first layer and the third layer may have respective thicknesses of less than or equal to 50 micrometers, in particular less than or equal to 20 micrometers, and wherein the second layer has a thickness greater than or equal to 200 micrometers, in particular greater than or equal to 500 micrometers.

[0025] This feature allows the first elongated sensor to be close to the internal surface of the inductor and therefore to the external contour of the part during the use of the inductor and the second sensor further away from the part and close to the cooling fluid.

[0026] Each elongated sensor may include an optical fiber, and in particular is a Bragg grating optical fiber sensor or a Rayleigh backscatter optical fiber sensor.

[0027] Such a feature makes it possible to monitor the temperature at a plurality of points with a single elongated sensor, along its extent.

[0028] Each elongated sensor may include a copper capillary radially surrounding the optical fiber.

[0029] Such a feature makes it possible to mechanically protect the optical fiber, which prevents the appearance of parasitic signals due to mechanical stresses, and also to facilitate its integration into the electroformed metallic layer.

[0030] Each optical fiber may have an external diameter less than or equal to 100 micrometers and has a profile adapted so that the fiber can achieve a radius of curvature less than or equal to 5 millimeters.

[0031] Such a feature allows better tracking of the external contour of the part by the optical fiber.

[0032] The preform can be made of polymer material, the preform being destroyed by chemical or thermal dissolution.

[0033] Such a preform is easy and quick to manufacture and can be removed simply, without having to keep an opening in the inductor allowing its passage.

[0034] The first metal can be silver and the second metal can be copper.

[0035] The invention also relates to an inductor comprising a hollow structure, made of a second metal, defining an internal conduit, the inductor having an internal surface shaped to follow an external contour of a mechanical part, the inductor comprising at least one elongated sensor embedded in the structure and extending between the internal conduit and the internal surface, parallel to said internal surface.

[0036] The inductor may include at least one control module connected to each elongated sensor, each control module being configured to collect information provided by said at least one sensor during the operation of the inductor. Brief description of the figures

[0037] [Fig-1] Fig. 1 is a perspective view of a part that can be induction hardened,

[0038] [Fig.2] [Fig.2] is a perspective view of a first manufacturing step of an inductor according to the invention adapted to the part of [Fig.1],

[0039] [Fig.3] [Fig.3] is a detailed view of the first step shown in [Fig.2],

[0040] [Fig.4] [Fig.4] is a schematic cross-sectional view of a second stage and a third stage of the manufacturing process.

[0041] [Fig.5] [Fig.5] is a schematic cross-sectional view of a fourth and fifth stage of the manufacturing process,

[0042] [Fig.6] [Fig.5] is a schematic cross-sectional view of a sixth and seventh step of the manufacturing process,

[0043] [Fig.7] [Fig.7] is a schematic cross-sectional view of the inductor obtained by the manufacturing process according to the invention. Detailed description of the invention

[0044] A mechanical part 1 is shown in [Fig.1], which includes an external contour 3 on which an induction heat treatment is to be applied.

[0045] In this example, part 1 is a gear wheel, comprising teeth 5 and grooves 7 which separate them, the outer contour 3 to be hardened following the teeth 5 and the grooves 7.

[0046] The external contour 3 is a complex and closed contour, exhibiting significant tortuosity, for which it is difficult to manufacture an inductor not comprising welding or brazing which would constitute a point of weakness.

[0047] A method for manufacturing an inductor for part 1 will now be described with reference to Figures 2 to 7.

[0048] In a first step, shown in figures 2 and 3, a preform 9 is formed, which follows the external contour 3 of the part 1.

[0049] The preform 9 is for example formed from a polymer material, using an additive manufacturing method.

[0050] The preform 9 completely and continuously surrounds the part 1, and has an internal surface 11 which extends near the contour 3, without direct contact.

[0051] The internal surface 11 extends in particular to a substantially constant distance d from the external contour 3, as shown in [Fig.3].

[0052] The distance d is for example between 1 millimeter and 10 millimeters, depending on the desired thickness of the inductor.

[0053] The preform 9 can be manufactured directly on the part 1, or by example from an imprint or a three-dimensional image of part 1.

[0054] The preform 9 is then coated with a thin layer 13 made of a first metal, following a conventional chemical reduction method via spraying.

[0055] The first metal is, for example, silver.

[0056] The thin layer 13 completely covers the preform 9 and has a thickness eO of, for example, between 0.1 micrometer and 1

[0057] The thin layer 13 is intended to allow subsequent metal deposition by electrodeposition.

[0058] The process then includes a step of depositing a first layer 15 of a second metal, on top of the thin layer 13.

[0059] The second metal is advantageously copper.

[0060] Alternatively, the second metal can be any conductive metal compatible with an electrodeposition technique.

[0061] The thin layer 13 and the first layer 15 are shown in [Fig.4], which is a cross-sectional view of the inductor after the two deposition steps.

[0062] The first layer 15 is deposited by electrodeposition in an electrolytic bath and completely covers the thin layer 13. It has a substantially constant thickness el, less than or equal to 50 micrometers, and in particular less than or equal to 20 micrometers. The thickness el of the first layer 15 is, for example, substantially equal to 5 micrometers.

[0063] The process then includes a step of placing a first elongated temperature sensor 17 on the first layer 15, on the side of the internal surface 11 of the preform 9.

[0064] The first elongated sensor 17 extends along the internal surface 11 over an entire internal periphery of the first layer 15.

[0065] The first elongated sensor 17 is, for example, an optical fiber adapted to be part of a Bragg grating optical fiber temperature sensor or a Rayleigh backscatter optical fiber sensor.

[0066] The optical fiber is advantageously housed in a copper capillary, which protects it during installation and facilitates its integration into the electroformed copper layers.

[0067] According to an unrepresented variant, several optical fibers can be put in place, extending along the internal surface 11 over portions of the internal periphery that are different from each other.

[0068] The optical fiber advantageously has an external diameter D of less than 100 micrometers and a profile adapted so that the fiber can achieve a bending radius of less than or equal to 5 millimeters. This allows the optical fiber to follow a tortuous path closely following the internal surface 11.

[0069] It is recalled that the principle of a Bragg grating fiber consists of locally modifying the refractive index of the fiber core, thus creating a series of gratings (Bragg gratings). Each grating reflects a specific wavelength, different from the other gratings. Each grating allows for the local measurement of a temperature. It is therefore possible to measure a multitude of temperature points on a single optical fiber.

[0070] It is also worth noting that a Rayleigh backscatter fiber exploits the imperfections inherent in the fiber (due to heterogeneities generated during manufacturing). These imperfections induce backscattering along the entire length of the fiber (similar to the presence of weakly reflective mirrors along the fiber). Exploiting this backscattering signal makes it possible to measure a physical phenomenon (temperature or deformation) and its location.

[0071] A second layer 19 of the second metal is then deposited over the first layer 15 and the first elongated sensor 17, by electroforming.

[0072] The second layer 19 is a thick layer, which has a thickness e2 greater than or equal to 200 micrometers, in particular greater than or equal to 500 micrometers, and for example substantially equal to 1 millimeter.

[0073] The second layer 19 completely covers the first layer 15 and the elongated sensor 17. Its thickness ensures the structural integrity of the inductor. Furthermore, the elongated sensor is embedded in the second layer 19, and thus has very good thermal contact with the inductor.

[0074] The steps of setting up the first elongated sensor 17 and of depositing the second layer 19 are shown schematically in [Fig.5].

[0075] The process then includes a step of fixing a second elongated sensor 21 on the second layer 19, opposite the internal surface 11 of the preform 9.

[0076] The second elongated sensor 21 is substantially identical to the first elongated sensor 17 and extends substantially parallel to it. It is also laterally offset relative to the first elongated sensor 17, in a direction perpendicular to their extent.

[0077] The second elongated sensor 21 is in particular an optical fiber, which advantageously has the same diameter D as the optical fiber of the first elongated sensor 17.

[0078] A third layer 23 of the second metal is then deposited over the second layer 19 and the second elongated sensor 21, by electrodeposition.

[0079] The third layer has a substantially constant thickness e3, less than or equal to 50 micrometers, and in particular less than or equal to 20 micrometers. The thickness e3 of the first layer 15 is for example approximately equal to 10 micrometers.

[0080] The third layer 23 completely covers the second layer and the second elongated sensor 21. The second elongated sensor 21 is covered by the third layer 23, which ensures good thermal contact with the inductor, as well as a durable fixing.

[0081] The result of the steps of setting up the second elongated sensor 21 and of depositing the third layer 23 is shown schematically in [Fig.6].

[0082] The process then includes a step of destroying the preform 9, by chemical and / or thermal dissolution, and of obtaining an inductor 25.

[0083] The inductor 25 is schematically represented on [Fig.7], during a hardening operation of an external contour 3 of the part 1, opposite which it is positioned.

[0084] The destruction of the preform 9 releases an internal channel 27 in the inductor 25, intended to accommodate a flow of coolant 29 during the operation of the inductor 25.

[0085] During the operation of the inductor 25, the first elongated sensor 17 and the second elongated sensor 21 are connected to respective control modules 31, 33, in order to provide temperature information during the induction thermal hardening process.

[0086] More specifically, the first elongated sensor 17 is located in the vicinity of the internal channel 27, and provides information relating to the cooling efficiency of the inductor 25.

[0087] The second elongated sensor 21 is located in the vicinity of an internal surface 35 of the inductor 25, which faces the part 1.

[0088] The second elongated sensor 21 therefore collects information relating to the heat flux 37 emitted by radiation from part 1, and thus makes it possible to monitor the changes in the surface temperature of part 1.

[0089] The temperature information for part 1 collected by the first and second sensors 17, 21 allows for real-time monitoring of the temperature distributions of part 1 during the operation of the inductor 25, which is thus a connected inductor. This makes it possible to adjust the heat treatment in real time in order to reduce the risk of overheating and obtain an improved result.

[0090] The described process thus makes it possible to manufacture in a simple way an inductor of complex shape, which does not have any point of weakness which would reduce its efficiency, and in which temperature sensors are integrated allowing detailed and localized monitoring of the hardening process.

[0091] The integration of the sensors into the electroformed layers of the inductor allows for better durability and long-term reliability, as well as improved thermal contact.

Claims

Demands

1. A method for manufacturing an inductor (25) for the surface treatment of a mechanical part (1), the method comprising the steps of: - producing a preform (9) adapted to follow an external contour (3) of the part (1), according to an additive manufacturing method, the preform (9) having an internal surface (11) facing the external contour (3) of the part (1), - depositing a thin layer (13) of a first metal onto the preform (9), according to a chemical reduction method by spraying, - depositing a first layer (15) of a second metal, over the thin layer, according to an electrolytic method, - positioning at least one first elongated sensor (17) extending over the first layer (15), facing the internal surface (11) of the preform (9), - depositing a second layer (19) of the second metal, over the first layer (15) and at least a portion of the first elongated sensor (17),and - destruction of the preform (9) and obtaining the inductor (25).

2. A method according to claim 1, wherein the method comprises, after the step of depositing the second layer (19) of the second metal, the steps of: - placing at least one second elongated sensor (21) on the second layer (19), facing the internal surface (11) of the preform (9), and - depositing a third layer (23) of the second metal, over the second layer (19) and at least a part of the second elongated sensor (23).

3. A method according to the preceding claim, wherein the first layer (15) and the third layer (23) have relative thicknesses (e1, e3) less than or equal to 50 micrometers, in particular less than or equal to 20 micrometers, and wherein the second layer (19) has a thickness (e2) greater than or equal to 200 micrometers, in particular greater than or equal to 500 micrometers.

4. A method according to any one of the preceding claims, wherein each elongated sensor (17, 21) comprises an optical fiber, and in particular is a Bragg grating optical fiber sensor or a Rayleigh backscatter optical fiber sensor.

5. Method according to the preceding claim, wherein each elongated sensor (17,21) comprises a copper capillary radially surrounding the optical fiber.

6. Method according to claim 5 or 6, wherein each optical fiber has an external diameter (D) less than or equal to 100 micrometers and has a profile adapted so that the fiber can achieve a radius of curvature less than or equal to 5 millimeters.

7. A method according to any one of the preceding claims, wherein the preform (9) is made of polymer material, the preform (9) being destroyed by chemical or thermal dissolution.

8. A method according to any one of the preceding claims, wherein the first metal is silver and the second metal is copper.

9. Inductor (25) comprising a hollow structure, made of a second metal, defining an internal conduit (27), the inductor (25) having an internal surface (35) shaped to follow an external contour (3) of a mechanical part (1), the inductor (25) comprising at least one elongated sensor (17, 21) embedded in the structure and extending between the internal conduit (27) and the internal surface (35), parallel to said internal surface (35).

10. Inductor (25) according to the preceding claim, wherein the inductor comprises at least one control module (31, 33) connected to each elongated sensor (17, 21), each control module (31, 33) being configured to collect information provided by said at least one sensor (17, 21) during the operation of the inductor (25).

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