DOUBLE-BODY INDUCTOR FOR THE HEAT TREATMENT OF A PINION

Abstract

The present invention relates to an inductor (15) for the heat treatment of gear teeth, comprising: - a first inductor body (17.1) capable of generating a first alternating magnetic field, and - a second inductor body (17.2) capable of generating a second alternating magnetic field, - said first inductor body (17.1) and said second inductor body (17.2) being intended to be inserted within the same interdental space (12) of the gear. Figure for the abbreviation: Figure 6

Description

Title of the invention: DOUBLE-BODY INDUCTOR FOR THE HEAT TREATMENT OF A PINION

[0001] The present invention relates to a double-body inductor for the heat treatment of a pinion. The invention finds a particularly advantageous, but not exclusive, application in the field of aeronautics, for performing induction hardening of pinions used for the transmission of mechanical power inside an aircraft engine.

[0002] Induction hardening, as is known per se, consists of exposing a steel part to an alternating magnetic field, causing heat to penetrate superficially by a film effect. The energy of the magnetic field is transformed into heat on the part by ferromagnetism (through hysteresis and eddy current effects) so as to increase its surface temperature, which can reach the hardening temperature (on the order of 900°C) in a few seconds. Induction hardening makes it possible to strengthen the surface of power transmission parts.

[0003] There are two induction hardening technologies: rotary hardening and tooth-by-tooth hardening. With rotary hardening, a fixed inductor surrounds a workpiece to perform the heat treatment on the entire workpiece simultaneously. This technology is generally used with gears having a diameter of less than 200 mm and a straight tooth geometry.

[0004] Following the “tooth-by-tooth” technology, the inductor moves from one tooth to another to process the workpiece. This technology is implemented with gears having a diameter greater than 200 mm and a straight or helical tooth geometry.

[0005] Figure 1 shows an angular sector of a pinion 1 having a plurality of teeth 2 and a plurality of interdental spaces 3. An inductor 4 has a body 5 for cooperating in a complementary manner with an interdental space 3 of the pinion 1. The inductor 4 has a current input branch 6.1 and a current output branch 6.2. The body 5 of the inductor 4 is successively inserted inside the interdental spaces 3 in order to perform the heat treatment of the pinion 1. The two branches 6.1 and 6.2 can be arranged adjacent to each other to obtain a compensating effect.

[0006] During tooth-by-tooth heating, undesirable effects may occur, including heating of adjacent teeth, resulting in over-tempering of the steel. These effects may be due to the interaction of magnetic fields generated by the current input and output branches with the teeth. The larger the pinion module The smaller the helix angle of the teeth, the more pronounced this effect. The helix angle of the teeth can also influence this effect.

[0007] It is also known to use a small inductor that slides between the teeth according to the desired hardening profile. However, with large helix angles, particularly those exceeding 15°, controlling the inductor's movement becomes critical, and achieving a consistent treatment becomes impossible.

[0008] Fig. 2 shows an angular sector of a pinion 1 having hardened ZI zones and Z2 zones in which the steel has been locally softened due to over-tempering of the adjacent teeth.

[0009] Furthermore, overheating the flanks of the teeth 2 and underheating the tooth roots can lead to hardening of the flanks without affecting the bottoms of the interdental spaces 3. Figure 3 thus shows an angular sector of a pinion 1 having hardened ZI zones and Z3 zones located at the bottom of the interdental space 3 that are only slightly heated and therefore not hardened by individual tooth quenching. Extending the heating time could ensure hardening of the bottom of the interdental space 3 but would compromise the material integrity of the remaining teeth 2 due to a risk of melting or of reaching undesired metallurgical states.

[0010] The high temperatures generated by induction heating necessitate continuous cooling of the inductor by a water circulation circuit. Furthermore, an adequate copper cross-section is required to carry the electrical power through the inductor. Indeed, the smaller the gear modulus, the smaller the inductor cross-section, which limits the inductor's cooling capacity and its ability to carry sufficient electrical power to perform the heat treatment.

[0011] The invention aims to effectively remedy the aforementioned drawbacks by providing an inductor for the heat treatment of teeth of a pinion, said pinion comprising a plurality of teeth and a plurality of interdental spaces comprising: - a first inductor body capable of generating a first alternating magnetic field, and - a second inductor body capable of generating a second alternating magnetic field, - said first inductor body and said second inductor body being intended to be inserted within the same interdental space of the pinion.

[0012] The invention thus makes it possible, thanks to the double-body configuration, to better control the distribution of the magnetic flux during induction hardening to obtain homogeneous heating of the teeth of a low-modulus gear. This avoids overheating of the flanks, underheating of the bottom of the interdental space, and over-tempering of the teeth adjacent. The invention also makes it possible to improve the efficiency and effectiveness of the heating by adding the heating potentials of the magnetically active inductor bodies, which reduces the need for electrical power and facilitates the cooling of the inductor.

[0013] According to one embodiment of the invention, the first inductor body is intended to be disposed in a first zone of said interdental space extending between a bottom of said interdental space and a pitch diameter of the pinion and the second inductor body is intended to be disposed in a second zone of said interdental space extending between the pitch diameter of the pinion and an outer diameter of the pinion passing through free ends of the teeth.

[0014] According to one embodiment of the invention, said inductor further comprises at least one magnetic field concentrator to homogenize a magnetic flux density inside areas of the pinion located around the interdental space in which the first body and the second body of the inductor are arranged.

[0015] According to one embodiment of the invention, said inductor comprises a first magnetic field concentrator and a second magnetic field concentrator arranged on either side of the first inductor body so as to direct the magnetic field towards a bottom of the interdental space.

[0016] According to one embodiment of the invention, said inductor comprises a magnetic field concentrator disposed near the free end of the pinion teeth so as to limit magnetic radiation outside the interdental space in which the first inductor body and the second inductor body are disposed and to redirect the first magnetic field and the second magnetic field towards the inside of said interdental space.

[0017] According to one embodiment of the invention, the magnetic field concentrator(s) comprise(s) at least one magnetic field passage opening.

[0018] According to one embodiment of the invention, said inductor further comprises a current input branch and a current output branch directed towards the interior of the pinion.

[0019] According to one embodiment of the invention, the current input branch and the current output branch each form an angle between 0 and 90 degrees, preferably of the order of 45 degrees, with respect to a corresponding lateral face of the pinion.

[0020] According to one embodiment of the invention, the current input branch and the current output branch are each surrounded by a magnetic shield made of an electrically conductive material, in particular copper.

[0021] According to one embodiment of the invention, the current input branch and the current output branch are each surrounded by a magnetic field concentrator.

[0022] According to one embodiment of the invention, the first inductor body and the second inductor body are hollow to allow the passage of a coolant liquid within the first inductor body and the second inductor body.

[0023] The present invention will be better understood and other features and advantages will become apparent upon reading the following detailed description, which includes embodiments given by way of illustration with reference to the accompanying figures, presented by way of non-limiting examples, which may serve to complete the understanding of the present invention and the explanation of its implementation and, where appropriate, contribute to its definition, on which:

[0024] [Fig-1] Fig. 1, already described, is a perspective view of an inductor according to the state of the technique arranged inside an interdental space of a gable;

[0025] [Fig.2] Fig.2, already described, is a photograph of an angular sector of a pinion including areas at the top of teeth that have undergone over-hardening during a tooth-by-tooth tempering;

[0026] [Fig.3] The [Fig.3], already described, is a photograph of an angular sector of a pinion comprising areas located at the base of the tooth that are underheated and not affected by the tooth-by-tooth hardening;

[0027] [Fig. 4a] [Fig. 4b] Figures 4a and 4b are perspective views of a sector angular pinion and an inductor according to the invention inserted inside an interdental space of the pinion from two different viewing angles;

[0028] [Fig.4c] Fig.4c is a perspective view illustrating an angle formed by the current input and output branches relative to the axis of the inductor of the corresponding interdental space;

[0029] [Fig.5] The [Fig.5] is a detailed perspective view of an inductor according to the invention inserted inside an interdental space of a pinion;

[0030] [Fig.6] The [Fig.6] is a cross-sectional view of an inductor according to the invention disposed inside an interdental space;

[0031] [Fig.7] Fig.7 is a schematic representation of the generated magnetic field by the inductor according to the present invention;

[0032] [Fig.8] The [Fig.8] is a partial perspective view of an alternative embodiment of a double-body inductor according to the present invention.

[0033] It should be noted that, in Figures 4a to 7, the structural and / or functional elements common to the different embodiments may have the same reference numerals. Thus, unless otherwise stated, such elements have identical structural, dimensional and material properties.

[0034] Figures 4a, 4b, 5 and 6 show an inductor 15 for the heat treatment of teeth of a pinion 10 with axis X, partially represented in the figures. The pinion 10 comprises a pinion body 13, a plurality of teeth 11 and a plurality of interdental spaces 12, an interdental space 12 extending between two consecutive teeth 11. The inductor 15 comprises a first inductor body 17.1 capable of generating a first alternating magnetic field and a second inductor body 17.2 capable of generating a second alternating magnetic field. The second inductor body 17.2 is separate from the first inductor body 17.1. The first inductor body 17.1 and the second inductor body 17.2 are intended to be inserted within the same interdental space 12 of the pinion 10. The first inductor body 17.1 and the second inductor body 17.2 can be inserted simultaneously within the same interdental space 12.

[0035] The first inductor body 17.1 is intended to be disposed in a first zone ZA of the interdental space 12 extending between a bottom of said interdental space 12 and a pitch diameter Dp of the pinion 10. The second inductor body 17.2 is intended to be disposed in a second zone ZB of said interdental space 12 extending between the pitch diameter Dp of the pinion 10 and an outside diameter De of the pinion 10 passing through the free ends of the teeth 11. The first inductor body 17.1 and the second inductor body 17.2 are offset from each other radially with respect to the axis X of the pinion 10. There is thus a radial space between the two bodies 17.1, 17.2.

[0036] The inductor 15 also includes at least one current input branch 18.1 and at least one current output branch 18.2. The inductor 15 may have two current input branches 18.1, each associated with a corresponding inductor body 17.1, 17.2, and two current output branches 18.2, each associated with a corresponding inductor body 17.1, 17.2, as shown in [Fig. 5]. Each current input branch 18.1 is then connected to a first corresponding end of an inductor body 17.1, 17.2. Each current output branch 18.2 is connected to a second corresponding end of an inductor body 17.1, 17.2.

[0037] Alternatively, the inductor 15 has a single current input branch 18.1 and a single current output branch 18.2, each of which splits into two to be connected to a corresponding end of the first inductor body 17.1 and the second inductor body 17.2. In this case, the current input branch 18.1 has a junction connected on one side to a first end of the inductor body 17.1 and on the other side to a first end of the inductor body 17.2. The current output branch 18.2 has a junction connected on one side to a second end of the inductor body 17.1 and on the other side to a second end of the inductor body 17.2.

[0038] More specifically, the first inductor body 17.1 and the second elongated inductor body 17.2 are made of an electrically conductive material, preferably copper. The first inductor body 17.1 and the second body Inductor 17.2 may have an axial length equal to an axial length of interdental space 12.

[0039] As illustrated in [Fig.6], the first inductor body 17.1 and the second inductor body 17.2 are hollow to allow the passage of a coolant within the first inductor body 17.1 and the second inductor body 17.2.

[0040] In this case, a cross-section of the first inductor body 17.1 has a generally triangular shape. Alternatively, a cross-section of the first inductor body 17.1 has a square, rectangular, round, oval, or polygonal shape, or any other shape suitable for the application.

[0041] A cross-section of the second inductor body 17.2 has an elongated shape with a longitudinal elongation extending in an orthoradial direction with respect to the X-axis of the pinion 10. The cross-section of the second inductor body 17.2 can have various shapes, such as an overall oval shape or one with several convex portions, a rectangular, square, cylindrical, polygonal shape, or any other shape suitable for the application. The first inductor body 17.1 and the second inductor body 17.2 can have the same shape or different shapes. The dimensions of the inductor bodies 17.1 and 17.2 are adapted according to the desired power.

[0042] The inductor 15 further comprises at least one magnetic field concentrator 20.1, 20.2, 20.3 for homogenizing the magnetic flux density within areas of the pinion 10 located around the interdental space 12 in which the first inductor body 17.1 and the second inductor body 17.2 are arranged. A magnetic field concentrator 20.1-20.3 may, for example, comprise a matrix of electrically insulating material charged with particles of electrically conductive material. The matrix is, for example, made of an insulating material, in particular plastic (thermoplastic or thermosetting). The particles of conductive material are, for example, carbon or metal particles. Alternatively, a magnetic field concentrator 20.1-20.3 is made entirely of a ferromagnetic material, for example ferrite or any other material suitable for the application.

[0043] Advantageously, as can be clearly seen in [Fig. 6], a first magnetic field concentrator 20.1 and a second magnetic field concentrator 20.2 are arranged on either side of the first inductor body 17.1 so as to direct the magnetic field towards the bottom of the interdental space 12. Indeed, the magnetic field can pass through a gap between the two magnetic field concentrators 20.1, 20.2 positioned opposite the bottom of the interdental space 12. The first magnetic field concentrator 20.1 and the The second 20.2 magnetic field concentrator can each be made in one part or in several parts arranged longitudinally next to each other.

[0044] The first magnetic field concentrator 20.1 is disposed between the first inductor body 17.1 and a flank of a first tooth 11. The second magnetic field concentrator 20.2 is disposed between the first inductor body 17.1 and a flank of a second tooth 11 adjacent to the first tooth 11. The first magnetic field concentrator 20.1 and the second magnetic field concentrator 20.2 are separated from the flanks of the first tooth 11 and the second tooth 11 by a corresponding air gap El, for example less than 1mm, in particular less than 0.7mm.

[0045] According to one embodiment, the first inductor body 17.1 is separated from the bottom of the interdental space 12 by an air gap E2 of less than 1mm, in particular of the order of 0.8mm.

[0046] The first inductor body 17.1 extends radially from a radial end face of the magnetic field concentrators 20.1, 20.2. The projection distance L1 of the first inductor body 17.1 from the magnetic field concentrators 20.1, 20.2 is less than 0.5mm, for example on the order of 0.2mm.

[0047] The second inductor body 17.2 is separated from the flanks of the first tooth 11 and the second tooth 11 by a corresponding air gap E3. The air gap E3 is, for example, less than 2 mm and is, for example, 1.5 mm.

[0048] Furthermore, a magnetic field concentrator 20.3 is disposed near the free end of the teeth 11 of the pinion 10 so as to limit magnetic radiation outside the interdental space 12 in which the first inductor body 17.1 and the second inductor body 17.2 are disposed, and to redirect the first and second magnetic fields into said interdental space 12. The magnetic field concentrator 20.3 has the form of a thin plate extending in an orthoradial plane with respect to the X-axis of the pinion 10. The magnetic field concentrator 20.3 has a width extending between two teeth 11 in an orthoradial direction with respect to the X-axis of the pinion 10 and a length extending along a longitudinal extension direction of the teeth 11. The longitudinal extension direction is measured along the X-axis of the pinion for teeth straight. The magnetic field concentrator 20.3 is positioned outside the pinion 10 at a distance L2 less than 1mm, in particular on the order of 0.5mm from the outside diameter De of the pinion 10. .

[0049] Preferably, as illustrated in Figures 4a and 4b, the current input branch 18.1 and the current output branch 18.2 are directed towards the inside of the pinion 10, i.e., towards the body of the pinion 10 and not outwards as is conventionally the case for existing inductors (see [Fig. 1]). This configuration allows limiting interactions with the tips of teeth 11, leading to the phenomenon of local over-revenue of teeth 11.

[0050] The current input branch 18.1 and the current output branch 18.2 each form an angle Al (see [Fig. 4b]) between 0 and 90 degrees (exclusive), preferably on the order of 45 degrees, with respect to a corresponding lateral face of the pinion 10. "On the order of" means a variation of plus or minus 10% from the stated value. The first and second lateral faces of the pinion 10 each correspond to an axial end face of the pinion 10. The angle Al is measured from a lateral face of the pinion 10 to the corresponding current input / output branch 18.1, 18.2. As illustrated in [Fig.4c], the current input branch 18.1 and the current output branch 18.2 each form an angle A2 with respect to the axis XI of the inductor 17 of the interdental space 12 between 0 degrees and 90 degrees (exclusive), preferably on the order of a helix angle of the teeth.

[0051] Advantageously, the current input branch 18.1 and the current output branch 18.2 are each surrounded by a magnetic shield 21 made of an electrically conductive material, in particular copper. These magnetic shields 21 act as shielding, absorbing the magnetic field generated by the branches 18.1, 18.2 in the vicinity of the teeth 11 of the pinion 10.

[0052] Alternatively, the current input branch 18.1 and the current output branch 18.2 are each surrounded by a magnetic field concentrator 23. These magnetic field concentrators 23 minimize the magnetic radiation of the branches 18.1, 18.2 and direct the magnetic field of the branches 18.1, 18.2 towards the pinion body 13.

[0053] Fig. 7 shows that the use of two inductor bodies 17.1, 17.2 and magnetic field concentrators 20.1, 20.2, 20.3 makes it possible to homogenize the magnetic flux density represented by the lines B and thus to better control the heating of the teeth 11 including at the base of the tooth, i.e. in the bottom of the interdental spaces 12.

[0054] It is possible to provide one or more magnetic field passage openings 26 inside the lateral magnetic field concentrators 20.1, 20.2 so as to create hot spots on the tooth flank areas 11 arranged opposite said openings 26. The magnetic field passage openings 26 can have a dimension between 0.5 mm and 1 mm.

[0055] The magnetic field passage openings 26 may have parallel edges. Alternatively, the magnetic field passage openings 26 may have non-parallel edges so as to present a cross-section that increases with distance from the inductor body. Such a configuration optimizes the heating surface.

[0056] The configuration of the inductor bodies 17.1, 17.2 (size and power), of the concentrators 20.1-20.3 and of the magnetic field passage openings 26 depends on a specification defining the hardening zones according to the needs related to a given application.

[0057] It is possible to use a spraying device to spray water during heating in order to control a heating temperature on the tooth heads 11 and on the edges of the pinion 10.

[0058] Depending on the shape of the teeth, the use of a double-body inductor allows for optimization of the design and dimensions of each inductor body 17.1, 17.2 in order to improve heating in the respective zones ZA and ZB. Figure 8 shows a second example of a configuration in which the inductor body 17.1 located at the bottom of the interdental space 12 has a generally triangular cross-section, and the inductor body 17.2 located on the open side of the interdental space 12 has a cylindrical shape. The opening or spacing between the inductor bodies 17.1 and 17.2 allows the contribution of thermal radiation from the heated zones in order to homogenize the heating.

[0059] The use of a two-body inductor 17.1 and 17.2 allows an additive effect of the magnetic fields of each body 17.1 and 17.2, which improves the efficiency of the heating while reducing the consumption of electrical energy.

[0060] Of course, the different features, variants and / or embodiments of the present invention can be combined with each other in various ways insofar as they are not incompatible or mutually exclusive.

[0061] Furthermore, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms, and other variants that a person skilled in the art may consider within the scope of the present invention, and in particular all combinations of the different modes of operation described above, which may be taken separately or in combination.

Claims

Demands

1. Inductor (15) for the heat treatment of teeth of a pinion (10), said pinion (10) comprising a plurality of teeth (11) and a plurality of interdental spaces (12), characterized in that said inductor (15) comprises: - a first inductor body (17.1) capable of generating a first alternating magnetic field, and - a second inductor body (17.2) capable of generating a second alternating magnetic field, - said first inductor body (17.1) and said second inductor body (17.2) being intended to be inserted inside the same interdental space (12) of the pinion (10).

2. Inductor according to claim 1, characterized in that the first inductor body (17.1) is intended to be disposed in a first zone (ZA) of said interdental space (12) extending between a bottom of said interdental space (12) and a pitch diameter (Dp) of the pinion (10) and the second inductor body (17.2) is intended to be disposed in a second zone (ZB) of said interdental space (12) extending between the pitch diameter of the pinion (10) and an outside diameter (De) of the pinion (10) passing through free ends of the teeth (11).

3. Inductor according to claim 1 or 2, characterized in that it further comprises at least one magnetic field concentrator (20.1, 20.2, 20.3) for homogenizing a magnetic flux density inside areas of the pinion (10) located around the interdental space (12) in which the first body (17.1) and the second body (17.2) of the inductor (15) are arranged.

4. Inductor according to any one of claims 1 to 3, characterized in that it comprises a first magnetic field concentrator (20.1) and a second magnetic field concentrator (20.2) arranged on either side of the first inductor body (17.1) so as to direct the magnetic field towards a bottom of the interdental space (12).

5. Inductor according to any one of claims 1 to 4, characterized in that it comprises a magnetic field concentrator (20.3) disposed near the free end of the teeth (11) of the pinion (10) so as to limit magnetic radiation outside of the interdental space (12) in which the first inductor body (17.1) and the second inductor body (17.2) are arranged and redirect the first magnetic field and the second magnetic field towards the interior of said interdental space (12).

6. Inductor according to claim 3 or 4, characterized in that the magnetic field concentrator(s) (20.1, 20.2) has at least one magnetic field passage opening (26).

7. Inductor according to any one of claims 1 to 6, characterized in that it further comprises a current input branch (18.1) and a current output branch (18.2) directed towards the inside of the pinion (10).

8. Inductor according to claim 7, characterized in that the current input branch (18.1) and the current output branch (18.2) each form an angle between 0 and 90 degrees, preferably of the order of 45 degrees, with respect to a corresponding lateral face of the pinion (10).

9. Inductor according to claim 7 or 8, characterized in that the current input branch (18.1) and the current output branch (18.2) are each surrounded by a magnetic shield (21) made of an electrically conductive material, in particular copper.

10. Inductor according to claim 7 or 8, characterized in that the current input branch (18.1) and the current output branch (18.2) are each surrounded by a magnetic field concentrator (23).

11. Inductor according to any one of claims 1 to 10, characterized in that the first inductor body (17.1) and the second inductor body (17.2) are hollow to allow the passage of a coolant within the first inductor body (17.1) and the second inductor body (17.2).

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