Method and system for surface treatment of a fastener element, using a high-power pulsed magnetron sputtering device.

Abstract

- Method and system for surface treatment of a fastener, using a high-power pulsed magnetron spraying device. - The method for treating a fastener, in particular a rivet (3), includes a surface treatment step to treat the surface (23) of at least a portion (22) of the fastener (3) using a high-power pulsed magnetron spraying device (2) so as to obtain a surface (23) that is both cleaned and provided with engravings whose shape and thickness can be controlled, thus providing a surface (23) with properties that promote good paint adhesion and do not require prior cleaning. Figure for the abstract: Fig. 1

Description

Title of the invention: Method and system for surface treatment of a fastener element, using a high-power pulsed magnetron sputtering device. technical field

[0001] The present invention relates to a method and a system for surface treatment of a fastening element, in particular a rivet. State of the art

[0002] It is known that the external surface of an aircraft fuselage, for example a transport aircraft, is covered with a layer of paint. Typically, the external surface of the fuselage includes the heads of fasteners, in particular rivets, which are used to fasten different sections of the fuselage together or to attach components to the fuselage. This surface, as well as the heads of the fasteners, are coated with paint.

[0003] To improve paint adhesion to the heads of fasteners, rivets are generally subjected, after a cleaning operation, to a treatment in the form of sulfuric acid anodizing. However, despite this treatment, paint adhesion to the heads of the fasteners is not perfect. In particular, the heads can be subject to a phenomenon called "rivet rash," which causes the paint to delaminate. This situation occurs particularly, though not exclusively, on rivet heads, especially those with a metal base, used in aircraft fuselage structures.

[0004] There is therefore a need to have an effective solution for obtaining fastener surfaces with improved adhesion properties for the application of paint. Description of the invention

[0005] The present invention aims to provide a solution to meet the aforementioned need. It relates to a method for processing a fastening element.

[0006] According to the invention, said method comprises a surface treatment step for treating the surface of at least a portion of the fastener using a high-power pulsed magnetron sputtering device. Advantageously, the surface treatment is implemented to obtain a surface of said portion of the fastener that is both cleaned and engraved.

[0007] Thus, thanks to the invention, the process uses a high-power pulsed magnetron sputtering device, of the HiPIMS type (for "High-Power Impulse"). Magnetron Sputtering (in English), which allows obtaining a surface with engravings whose shape and thickness can be adapted, as specified below, in order to obtain in particular deep and homogeneous engravings, which makes it possible to generate a surface with properties that promote good adhesion of a paint.

[0008] In addition to producing an engraved surface, the surface treatment also results in a cleaned surface, particularly by removing the natural oxide layer. Therefore, it is not necessary to perform a preliminary surface cleaning operation before treatment.

[0009] In a preferred embodiment, the surface treatment step includes a tuning operation to adjust at least one parameter of the high-power pulses to be generated by the high-power pulsed magnetron sputtering device. Advantageously, the parameter(s) to be adjusted of the high-power pulses represent at least one of the following parameters: - the pulse power; - the duration of the pulses; - the pulse frequency.

[0010] Furthermore, advantageously, the surface treatment step performs a surface treatment of a head of the fastening element.

[0011] The present invention also relates to a system for processing a fastening element.

[0012] According to the invention, said system comprises a high-power pulsed magnetron spraying device, for performing a surface treatment of at least a part of the fastening element.

[0013] Advantageously, the high-power pulsed magnetron spraying device includes a control unit configured to allow an operator to set at least one parameter of high-power pulses to be generated by the high-power pulsed magnetron spraying device. Brief description of the figures

[0014] The accompanying figures will clearly illustrate how the invention can be implemented. In these figures, identical reference numerals designate similar elements.

[0015] Fig. 1 is a schematic view of a particular embodiment of a surface treatment system comprising a high-power pulsed magnetron sputtering device.

[0016] Fig. 2 is a perspective view of a fastening element corresponding to a rivet, which has been treated by the surface treatment system.

[0017] The [Fig.3] is the synoptic diagram of a process for treating a fastening element using the surface treatment system. Detailed description

[0018] System 1, which illustrates the invention and is schematically represented in a particular embodiment in [Fig. 1], is intended to handle a fastening element.

[0019] More specifically, although not exclusively, the fastening element is a fastening element used on an aircraft, in particular on a transport aircraft.

[0020] System 1 is particularly well suited to a fastener corresponding to a rivet 3 as shown in [Fig. 2]. It can also be applied to other fasteners such as bolts, screws, etc. These fasteners can be made of various metallic materials, such as, but not limited to and by way of example only, titanium-based or aluminum-based metals.

[0021] To this end, the system 1 comprises a high-power pulsed magnetron sputtering device (hereinafter "device 2") of the HiPIMS type (for "High-Power Impulse Magnetron Sputtering"). This device 2 is used to perform a surface treatment on at least a portion of the fastening element.

[0022] In the application to a rivet 3 as shown in [Fig.2], which includes a head 20 and a cylindrical body 21, the treatment is carried out on the external surface 22 of the head 20, i.e. on the surface of the head 20 opposite to that connected to the body 21.

[0023] As shown in [Fig. 1], the device 2 comprises a chamber 4 forming a closed and gas-tight enclosure. This chamber 4 is provided with a cathode 5 comprising a magnetron 6. The magnetron 6 is typically provided with an array 7 of magnets 8. A target material (or donor material) 9, specified below, is associated with the magnetron 6.

[0024] Chamber 4 is also provided with an anode 10 facing the cathode 5. The anode 10 receives the fastening element to be treated. By way of non-limiting illustration, a plurality of fastening elements (in this case rivets 3) are shown in [Fig. 2]. The anode 10 is connected to ground or to a reference potential.

[0025] The device 2 also includes a vacuum pump 11 connected via a valve 12 to the chamber 4. The vacuum pump 11 is configured to generate a vacuum in the chamber 4. The vacuum pump 11 makes it possible to create a controlled environment for surface treatment.

[0026] The device 2 further comprises a gas supply system 13, which is connected via a valve 14 to the chamber 4. The system 13 is configured to supply chamber 4 with gas, namely an inert gas 15 as specified below, which is illustrated by black dots on [Fig.1].

[0027] Furthermore, device 2 includes a power supply system 16. The power supply system 16 is connected to the cathode and is capable of generating high-power pulses. The parameters of these pulses (duration, frequency, power) are adjusted, as specified below, particularly according to the characteristics of the surface treatment to be performed.

[0028] Device 2 also includes a control unit 17. The control unit 17 is, in particular, provided with a human-machine interface 17A enabling an operator to perform commands and adjustments, and in particular the adjustment of parameters of the pulses generated by the system 16. The control unit 17 is configured to control device 2. More particularly, the control unit 17 is capable of controlling the power supply system 16, as illustrated by an arrow 18 in [Fig. 1], as well as other elements of device 2, as illustrated by an arrow 19.

[0029] The system 1, as described above, is suitable for implementing a process P for processing a fastener element, in particular a rivet 3. To do this, the process P includes in particular the steps described below.

[0030] The process P includes, as shown in [Fig.3], a preparation step El during which the target material 9, generally a metallic material, is installed in the chamber 4. In addition, the fasteners to be treated are also introduced into the chamber 4 and are positioned so that their surface to be treated is located opposite the target material 9, as shown in the example in [Fig.1] where the surfaces 22 of the rivets 3 are located opposite the target material 9.

[0031] Then, a vacuum is created in chamber 4 using the vacuum pump 11, in order to remove all unwanted air particles from chamber 4.

[0032] Furthermore, chamber 4 is supplied with gas by means of the gas supply system 13. The gas introduced into chamber 4 is an inert gas 15 which must behave in a chemically neutral manner and is used to generate a plasma. By way of illustration, argon or nitrogen can be used as the inert gas. The inert gas 15 is introduced into chamber 4 until a suitable pressure is reached therein.

[0033] The process P then comprises a surface treatment step E2. This surface treatment step E2 includes plasma generation. To do this, high-power pulses (for example, on the order of several kilowatts to megawatts) are applied by the power supply system 16 to the cathode 5 for a very short duration (for example, from a few microseconds to a few milliseconds). The pulse frequencies range, for example, from a few Hz to a few kHz.

[0034] These pulses create an intense electric field around the cathode 5, which ionizes the atoms of the inert gas 15 introduced into the chamber 4, generating a particularly dense plasma. These pulses make it possible to form a highly energetic plasma.

[0035] The gas ions (thus formed) are directed towards the cathode 5, as illustrated by arrows Fl in [Fig. 1]. These gas ions bombard the surface 9A of the target material 9 arranged at the cathode 5. This bombardment removes atoms from the target material 9.

[0036] Magnetic fields are generated in the device 2 by means of the magnets 8. These magnetic fields bend the paths of the electrons so that they strike as many gas atoms near the target as possible to ionize them. This creates a high concentration of gas ions near the target material 9, which strike said target material 9 through the applied voltage. The higher the applied voltage, the greater the energy with which the gas ions strike or bombard the target material 9.

[0037] The atoms that are removed from the target material 9 are ionized to a large extent due to the high density of the plasma. The removed and ionized atoms move towards the fasteners to be treated, namely the rivets 3, as illustrated by arrows F in [Fig. 1], and act on the surfaces 22 of the rivets 3 to be treated, in order to treat them.

[0038] The surface treatment, thus implemented, makes it possible to obtain surfaces 22, which are both cleaned and provided with engravings.

[0039] The engravings 23 obtained on the surface 22 of a rivet 3 are represented very schematically on [Fig.3] by thin lines.

[0040] Thanks in particular to the adaptation of the high-power pulse parameters and possibly the adjustment of other parameters of the device 2, the shape and thickness of the engravings 23 can be precisely controlled so that they exhibit the desired characteristics. In particular, the high ionization of the metallic plasma makes it possible to generate deep engravings. This allows for the creation of surfaces 22 with deep and homogeneous engravings 23, resulting in surfaces 22 with properties that promote good paint adhesion.

[0041] In addition to obtaining a surface with engravings 23, the surface treatment also makes it possible to obtain a cleaned surface 22, in particular by the elimination (by the surface treatment implemented) of the natural oxide layer, initially present on the surface 22. Therefore, with the process P, it is not necessary to carry out a preliminary cleaning operation of the surface before its treatment.

[0042] The properties of the surface treatment thus carried out (on the surfaces 22 of the rivets 3 in the example of [Fig.1]) can be adapted.

[0043] More specifically, to obtain the treatment appropriate to the application under consideration, various parameters can be adjusted and adapted. In particular, several parameters of the high-power pulses (generated by the system 16) can be adjusted by an operator, using the human-machine interface 17A, and in particular: - the pulse power, which has an influence, in particular, on the plasma density and the sputtering rate. Higher power results in higher ionization and more effective surface treatment; - the duration of the pulses, which influences the effectiveness of the treatment and the heat generated; and - The pulse frequency influences the treatment frequency and thus the overall duration of the surface treatment. A higher frequency allows for faster surface treatment.

[0044] Other parameters of the device 2 can also be adjusted, in particular the pressure of the chamber 4, which influences the trajectory of the sprayed atoms. In particular, a lower pressure promotes more direct trajectories, thereby increasing the uniformity of the surface treatment.

[0045] Device 2 thus presents, in particular, the following advantageous characteristics: - high ionization; - precise control, particularly of the thickness and shape of the engravings; - uniform processing.

[0046] The device 2 of the system 1 therefore uses high-power pulses which make it possible to generate a dense plasma and to improve the quality of the surface treatment carried out, while allowing precise control of the characteristics of said surface treatment.

[0047] System 1 is particularly well suited to metallic rivets 3, which are used in structures, for example, but not limited to, composite or aluminum structures, particularly aircraft fuselages, and which are particularly susceptible to the phenomenon of "rivet rash". The surface treatment thus achieved by system 1 significantly improves the adhesion of paint applied after the surface treatment, which greatly reduces the occurrence of paint delamination, while eliminating the need for a preliminary cleaning operation required in conventional treatments.

[0048] System 1 and method P, as described above, thus make it possible to obtain a surface (of a fastening element) provided with engravings, including in particular the shape and the thickness can be controlled, which have properties that promote good adhesion of paint to this surface.

[0049] In addition, the surface treatment also makes it possible to obtain a cleaned surface so that it is not necessary to carry out a preliminary cleaning operation of the surface before its treatment, which makes it possible to reduce the number of operations to be carried out as well as the total time of the operations carried out on the fastening elements.

Claims

Demands

1. A method for treating a fastener, in particular a rivet, characterized in that it comprises a surface treatment step (E2) for treating the surface of at least a part (22) of the fastener (3) using a high-power pulsed magnetron spraying device (2).

2. A method according to claim 1, characterized in that the surface treatment is carried out to obtain a surface (22) that is both cleaned and provided with engravings (23) of said part (22) of the fastening element (3).

3. A method according to any one of claims 1 and 2, characterized in that the surface treatment step (E2) includes a tuning operation to adjust at least one high-power pulse parameter to be generated by the high-power pulsed magnetron sputtering device (2).

4. A method according to claim 3, characterized in that the parameter(s) to be set for high-power pulses represent at least one of the following parameters: - the power of the pulses; - the duration of the pulses; - the frequency of the pulses.

5. A method according to any one of the preceding claims, characterized in that the surface treatment step (E2) performs a surface treatment (22) of a head (20) of the fastening element (3).

6. Fastening element treatment system, characterized in that it comprises a high-power pulsed magnetron spraying device (2) for performing surface treatment of at least a portion (22) of the fastening element (3).

8. System according to claim 7, characterized in that the high-power pulsed magnetron sputtering device (2) comprises a control unit (17) configured to allow an operator to adjust at least one parameter of high-power pulses to be generated by the high-power pulsed magnetron sputtering device (2).

Images