INDUCTION WELDING PROCESS FOR WELDING TWO PARTS USING AT LEAST ONE SUSCEPTOR COMPRISING DISCONTINUOUS CONDUCTIVE ELEMENTS, AND ASSEMBLY OF AT LEAST TWO PARTS OBTAINED USING SAID INDUCTION WELDING PROCESS

Abstract

Induction welding process for welding two parts using at least one susceptor including discontinuous conductive elements, and assembly of at least two parts obtained using the induction welding process. An induction welding process can join at least first and second parts, and the process can include a step of positioning at least one susceptor, including discontinuous conductive elements, between the first and second contact faces of the first and second parts, and steps of holding the first and second parts pressed against each other and of producing an electromagnetic field to generate an induced current that engenders heating of the susceptor. An assembly of two parts can be obtained using the process.

Claims

1. An induction welding process for joining at least first and second parts having first and second contact faces joined by at least one induction weld, the induction welding process comprising: positioning at least one susceptor between the first and second contact faces; holding the first and second parts pressed against each other; and producing an electromagnetic field to generate an induced current that engenders heating of the susceptor, wherein the susceptor comprises a plurality of discontinuous conductive elements.

2. The induction welding process according to claim 1, wherein each discontinuous conductive element takes a form of a closed loop.

3. The induction welding process according to claim 2, wherein each discontinuous conductive element is a circular closed loop and is inscribed in a square with a side length shorter than or equal to 7 mm.

4. The induction welding process according to claim 1, wherein the susceptor takes a form of a sheet, the discontinuous conductive elements being positioned in a plane of the sheet.

5. The induction welding process according to claim 4, wherein the sheet has a thickness smaller than or equal to 2 mm.

6. The induction welding process according to claim 1, wherein the discontinuous conductive elements cover from 20 to 40% of a total area of the susceptor.

7. The induction welding process according to claim 1, wherein the discontinuous conductive elements are made of copper.

8. The induction welding process according to claim 1, wherein the inductor is parameterized so that the electromagnetic field has a frequency lower than 50 kHz.

9. The induction welding process according to claim 1, wherein the induction welding process comprises generating at least one complementary electromagnetic field, in addition to the field generated by the inductor.

10. The induction welding process according to claim 1, used to assemble at least one stiffener and one panel, the stiffener being positioned against a contact face of the panel, wherein the inductor is positioned opposite the contact face of the panel when it generates the electromagnetic field that produces the induction weld.

11. An assembly of at least first and second parts, the assembly being obtained by the induction welding process according to claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0022] Other features and advantages will become apparent from the following description of the disclosure herein, which description is given merely by way of example, with reference to the appended drawings, in which:

[0023] FIG. 1 is a side view of an induction welded assembly of two parts, illustrating one embodiment of the prior art;

[0024] FIG. 2 is a top view of the assembly shown in FIG. 1;

[0025] FIG. 3 is a curve of temperature in a cross-sectional plane of the assembly shown in FIG. 1 at the moment of the induction welding;

[0026] FIG. 4 is a side view of an induction welded assembly of two parts, illustrating one embodiment of the disclosure herein;

[0027] FIG. 5 is a top view of the assembly shown in FIG. 4;

[0028] FIG. 6 is a temperature curve in a cross-sectional plane of the assembly shown in FIG. 4 at the moment of the induction welding;

[0029] FIG. 7 is a cross-section of an assembly of two parts joined by induction welding, illustrating one embodiment of the disclosure herein;

[0030] FIG. 8 is a top view of a pattern of a susceptor, illustrating a first embodiment;

[0031] FIG. 9 is a top view of a pattern of a susceptor, illustrating a second embodiment;

[0032] FIG. 10 is a top view of a pattern of a susceptor, illustrating a third embodiment;

[0033] FIG. 11 is a top view of a susceptor, illustrating one embodiment of the disclosure herein;

[0034] FIG. 12 is a top view of a susceptor, illustrating another embodiment of the disclosure herein; and

[0035] FIG. 13 is a perspective view of a complementary electromagnetic circuit, illustrating one embodiment of the disclosure herein.

DETAILED DESCRIPTION

[0036] FIG. 7 shows an assembly 22 comprising at least first and second parts 24, 26 that have first and second contact faces F24, F26 joined by at least one induction weld 28. Below, by an interface 30 of the first and second parts 24, 26, what is meant is the zone located between the first and second contact faces F24 and F26 and in which at least one induction weld 28 is produced.

[0037] According to one embodiment, the weld 28 is obtained using an induction welding process that comprises steps of holding the first and second parts 24, 26 pressed against each other and of producing an electromagnetic field 32 so as to generate an induced current that engenders heating at the interface 30 of the first and second parts 24, 26.

[0038] The tool used to implement the induction welding process comprises a clamping system for holding the first and second parts 24, 26 pressed against each other, and an inductor 34.

[0039] According to one embodiment, the clamping system comprises at least one peripheral seal, positioned on the periphery of the interface 30 in order to isolate it, and a pumping mechanism configured to generate a vacuum in the interface so as to hold the first and second parts 24, 26 pressed against each other.

[0040] According to another embodiment, the clamping system comprises, on the one hand, a bladder that covers at least one of the first and second parts 24, 26, at least one peripheral seal positioned on the periphery of the bladder so as to isolate a cavity in which the interface 30 is positioned and, on the other hand, a pumping mechanism configured to generate a vacuum inside the cavity so as to hold the first and second parts 24, 26 pressed against each other.

[0041] Of course, the disclosure herein is not limited to this embodiment as regards the clamping system, the latter being configured to generate a contact pressure that is substantially uniform over all the area of the first and/or second contact face(s) F24, F26.

[0042] The inductor 34 is configured to generate an electromagnetic field at the interface 30.

[0043] The assembly 22 comprises at least one susceptor 36 positioned in the interface 30, between the first and second contact faces F24, F26. The presence of a susceptor 36 allows the heating to be concentrated in the susceptor 36 and the temperature levels in the first and second parts 24, 26 to be limited. Thus, the induction welding process comprises a step of positioning at least one susceptor 36 in the interface 30, between the first and second contact faces F24, F26.

[0044] According to one feature of the disclosure herein, the susceptor 36 comprises a plurality of discontinuous conductive elements 38, which do not extend from one edge to the other of the susceptor 36. This configuration limits the appearance of a temperature gradient between the center and edges of the susceptor 36. Thus, as illustrated in FIG. 6, the temperature is substantially uniform over all the area of the susceptor 36.

[0045] The discontinuous conductive elements 38 are separate and each takes the form of a closed loop. Thus, the closed-loop shape allows the induced current generated by the electromagnetic field to be looped back onto itself.

[0046] The discontinuous conductive elements 38 may each describe a square or rectangular pattern, as illustrated in FIG. 8; a circular pattern, as illustrated in FIG. 9; or a triangular pattern, as illustrated in FIG. 10. Of course, the disclosure herein is not limited to these patterns as regards the closed loops.

[0047] The susceptor 36 takes the form of a sheet comprising a plurality of discontinuous conductive elements 38 positioned in the same plane, that of the sheet. This sheet has a thickness smaller than or equal to 2 mm. In one configuration, the sheet has a thickness of about 80 m.

[0048] According to another feature, the discontinuous conductive elements 38 cover from 20 to 40% of the total area of the susceptor 36. In one configuration, the discontinuous conductive elements 38 cover 30% of the total area of the susceptor 36.

[0049] According to one embodiment, to obtain a temperature that is uniform over a zone of the susceptor 36, the susceptor 36 has, in this zone, identical uniformly-distributed discontinuous conductive elements 38, as illustrated in FIGS. 11 and 12.

[0050] According to one embodiment shown in FIG. 11, the discontinuous conductive elements 38 are circular closed loops that are each inscribed in a square of 7 mm side length.

[0051] According to a second embodiment shown in FIG. 12, the discontinuous conductive elements 38 are circular closed loops that are each inscribed in a square of 3.5 mm side length.

[0052] Whatever the embodiment, each discontinuous conductive element 38 is inscribed in a square with a side length shorter than or equal to 7 mm.

[0053] The susceptor 36 is made of metal. According to one optimized embodiment, the susceptor 36 (and more particularly the discontinuous conductive elements 38) is made of copper.

[0054] The susceptor 36 may comprise discontinuous conductive elements 38 that are all identical, and that are distributed uniformly over all the area of the susceptor 36. As a variant, the susceptor 36 may comprise a plurality of zones each with discontinuous conductive elements 38, with different patterns from one zone to the next and/or with different distributions from one zone to the next. This configuration allows the susceptor 36 to be adapted depending on the geometry of the first and second parts 24, 26.

[0055] According to one embodiment, the inductor 34 may be identical to those of the prior art. The same inductor 34 may be used for various configurations of parts. According to the disclosure herein, it is the susceptor 36 that is adjusted depending on the configuration of the parts to be assembled and not the inductor 34.

[0056] In one configuration, the inductor 34 is parameterized so that the electromagnetic field has a frequency lower than 50 kHz, and preferably comprised between 20 and 30 kHz.

[0057] In order to obtain a power of 100 W at the susceptor 36, with a frequency of 50 kHz, an electromagnetic field of about 18400 A/m is necessary.

[0058] According to one embodiment, the tool for implementing the induction welding process comprises, in addition to the clamping system and the inductor 34, at least one complementary magnetic circuit 40 configured to generate a complementary electromagnetic field 42, as illustrated in FIG. 13. Thus, the induction welding process comprises a step of generating at least one complementary electromagnetic field 42, in addition to the field generated by the inductor 34. This configuration allows the power required for the induction welding to be obtained with a low-frequency, using an existing inductor 34.

[0059] In one application, the first part 24 is a stiffener that has an L-shaped cross section and the second part 26 is a panel, such as for example the skin of an aircraft. In this application, the inductor 34 is positioned opposite the contact face F26 when it generates the electromagnetic field that produces the induction weld. This configuration, combined with a low-frequency, allows the temperature in the first and second parts 24, 26 to be limited.

[0060] While at least one example embodiment of the invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the example embodiment(s). In addition, in this disclosure, the terms comprise or comprising do not exclude other elements or steps, the terms a, an or one do not exclude a plural number, and the term or means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.