A method for separating a first machine part from a second machine part.

Abstract

The present invention relates to a method for separating a first mechanical component (12) from a second mechanical component (14), the second mechanical component (14) being bonded to the first mechanical component (12) by an adhesive film (16) along the bonding area, the first mechanical component (12) having a first specific thermal conductivity and the second mechanical component having a second thermal conductivity higher than the first thermal conductivity, the method being characterized in comprising at least one cooling step in which the second mechanical component (14) is cooled to a negative temperature and at least one stress application step in which the second mechanical component (14) is subjected to a mechanical stress in order to break the adhesive film (16).

Description

Technical Field

[0001] The present invention relates to a method for separating a first mechanical part from a second mechanical part. The present invention is particularly applicable to a method for separating a metal reinforcement from the leading edge of a turbo machine vane made of a composite material.

Background Art

[0002] A fan-mounted double-flow turbo machine is equipped with vanes that can be mainly made of an organic matrix composite material. These vanes are usually equipped with metal reinforcements made of titanium alloy that are joined to the vanes, for example, at the leading edge of the vanes.

[0003] During use, the metal reinforcements of one or more vanes may be damaged by various impacts when foreign objects such as birds or debris are sucked in by the fan. However, in this case, the corresponding vane is not necessarily damaged, so for the production of composite materials, replacing only the metal reinforcement and retaining the composite vane would be valuable because the latter has a high economic value.

[0004] Therefore, an object of the present invention is to develop a method for separating a metal reinforcement from a vane made of a composite material without damaging the vane.

[0005] Various techniques known from the prior art have been used so far to separate metal reinforcements from vanes.

[0006] French Patent Application Publication No. 2970197 discloses a method for inductively separating a first mechanical part from a second magnetic mechanical part joined to the first mechanical part by an adhesive film. In this method, by utilizing the magnetic properties of the second magnetic mechanical part, a magnetic field is generated in the joining region so that eddy currents are inductively generated in the second magnetic mechanical part, thereby heating the two parts and softening the joined adhesive film to enable separation of the mechanical parts.

[0007] A drawback of this method when applied to vane reinforcement is that the thickness of the vane is not uniform. In particular, the reinforcement has a high thickness at the level of the leading edge of the vane and becomes thinner in the extended region that extends inward from this leading edge and is bonded to the surface of the vane by an adhesive film.

[0008] The magnetic field used to reach a sufficient temperature rise in the reinforcement at the higher thickness regions can cause overheating in the lower thickness regions of the reinforcement. This overheating can transfer to the vane composite material, potentially degrading it.

[0009] The French Patent Application Publication No. 3056605 discloses a separation method by dissolution. In this method, a portion of a vane, which has a leading edge reinforcement made of titanium alloy, is immersed in a chemical treatment tank supplied by a closed circuit through which a chemical treatment composition circulates and a closed circuit through which a rinse composition circulates. The titanium alloy is dissolved by circulating the chemical treatment composition, and then the vane is rinsed.

[0010] This solution has the disadvantages of requiring relatively bulky and complex equipment and exhibiting long processing times due to the melting of the titanium reinforcement. Furthermore, since the latter material is melted, it cannot be recycled.

[0011] The U.S. Patent Application Publication No. 2014 / 030108 describes a method for separating an assembly comprising an adhesive film filled with a shape memory material by heating and applying mechanical stress, wherein the heating is performed at a temperature higher than the martensitic transformation temperature of the material. This highly specialized adhesive can only be used in very limited ways.

[0012] French Patent Application Publication No. 3025735 and French Patent Application Publication No. 2992243 describe a method of separating an assembly by cooling it and applying mechanical stress so that the entire assembly is cooled. In this configuration, it is not possible to utilize the differences in thermal conductivity between materials. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] French Patent Application Publication No. 2970197 Specification [Patent Document 2] French Patent Application Publication No. 3056605 [Patent Document 3] U.S. Patent Application Publication No. 2014 / 030108 [Patent Document 4] French Patent Application Publication No. 3025735 Specification [Patent Document 5] French Patent Application Publication No. 2992243 [Overview of the project]

[0014] The present invention improves upon this drawback by proposing a method that allows for the separation of a first mechanical component from a second mechanical component and the breakdown of the connection between the adhesive film and the second mechanical component having higher thermal conductivity.

[0015] More specifically, the present invention proposes a method for breaking the interface between the adhesive and the material of a second mechanical component by applying thermal stress to the second mechanical component on the one hand and mechanical stress to the second component on the other hand.

[0016] This second component has a higher thermal conductivity than the first component, and its high thermal conductivity allows it to rapidly transfer thermal stress, which, combined with mechanical stress, makes it possible to break the adhesive film.

[0017] For this purpose, the present invention proposes a method for separating a first mechanical component from a second mechanical component, wherein the second mechanical component is bonded to the first mechanical component by an adhesive along a bonding region, the first mechanical component has a first specific thermal conductivity, the second mechanical component has a second thermal conductivity higher than the first thermal conductivity, and the method comprises at least one cooling step in which only the second mechanical component is cooled to a negative temperature, and at least one stress application step in which the second mechanical component is subjected to mechanical stress to break the adhesive film.

[0018] According to other features of this method, - The cooling step and the stress application step are performed simultaneously. -During the stress application step, the second component is subjected to compressive stress in a direction substantially perpendicular to the surface of the adhesive film. - Compressive stress is applied by vibration means or projection means. - The vibration means is an ultrasonic hammering means, and the projectile projection means is a blasting means. - The cooling step is performed by projecting liquid nitrogen onto the second component. - The first component is a vane made of a composite material, and the second component is a metal reinforcement bonded to the leading edge of the vane, and the method comprises two simultaneous steps: cooling the metal reinforcement by projecting liquid nitrogen, and subjecting the reinforcement to mechanical stress by ultrasonic hammering in a direction substantially perpendicular to the surface of the adhesive film, - The method is carried out by a tool whose length is shorter than the length of the leading edge of the vane, which enables simultaneous cooling and stress application within the covering area of ​​the leading edge of the vane, and the tool is moved along the entire length of the leading edge of the vane. -Liquid nitrogen is projected at a temperature of substantially -200°C, and the ultrasonic hammering is performed at a frequency of 10kHz to 40kHz.

[0019] The present invention also relates to a tool for separating a first machine part from a second machine part by the method described above, the tool being characterized in that it includes an assembly that can move translationally along the free surface of the second machine part, the assembly comprising: - a stress application unit, a generator that converts the electric power supplied to the generator into a sine wave electric signal, a converter that converts the sine wave electric signal into a sine wave vibration wave, an amplifier that amplifies the vibration wave, a sonotrode adapted to transmit the vibration wave, at least one transmission finger arranged close to the second part and configured to receive the vibration waves of the sonotrode and mechanically transmit them to the second part, and a stress application unit that continuously includes the above, - a cooling unit, a pressurized nitrogen storage tank, an expander configured to receive nitrogen from the tank and supply this nitrogen at a predetermined pressure, a conduit extending near the second part to which pressurized nitrogen is supplied by the expander, a nozzle arranged at the end of the conduit and configured to spray liquid nitrogen on the surface of the second part, and a cooling unit that continuously includes the above, and includes.

[0020] Other details, features and advantages of the present invention will be better understood and more clearly revealed from the following description made with reference to the accompanying drawings as non-limiting examples.

Brief Description of the Drawings

[0021] [Figure 1] Figure 1 is a schematic cross-sectional view of a turbo machine blade. [Figure 2] Figure 2 is a schematic perspective view of the blade of Figure 1. [Figure 3] Figure 3 is a plan view of the tool according to the present invention during the implementation of the method according to the present invention. [Figure 4] Figure 4 is another plan view of the tool according to the present invention in the process of implementing the method according to the present invention. [Modes for carrying out the invention]

[0022] Figure 1 shows a turbomachinery vane assembly 10. As is well known, the vane assembly 10 consists of two parts 12 and 14 joined by an adhesive film 16, the thickness of which is exaggerated for the sake of understanding Figure 1. Thus, the adhesive film 16 defines a connection area 18 between the two parts.

[0023] The first mechanical part 12 has a specific thermal conductivity, and the second part 14 has a higher thermal conductivity 14 than the first part 12.

[0024] In the case of the turbomachinery vane assembly 10, the first component is a vane 12 made of a composite material, such as an organic composite material, and the second component is a metal reinforcement 14 made of a titanium alloy that is bonded to the leading edge 20 of the vane 12.

[0025] As shown in Figure 2, the reinforcing member 14 extends along the length L of the leading edge 20 of the vane 12.

[0026] Conventionally, separation methods known in the prior art involve either softening the adhesive film 16 by induction heating of the reinforcing material 14, or performing a chemical dissolution operation of the reinforcing material 14.

[0027] As can be seen from Figure 1, the thickness of the reinforcing material 14 is not uniform. The reinforcing material 14 caps the vane 12 and has a thickness E that is maximum at the level of the leading edge 20 and decreases to a minimum in the regions 26 and 28 where the reinforcing material joins the outer region 22 and the inner region 24 of the vane 12.

[0028] As a result, the induction heating of the reinforcing material 14 to sufficiently soften the adhesive film 16 at the leading edge height causes excessive heating in regions 26 and 28, which has the disadvantage of potentially leading to degradation of the vane 12 near these regions. Therefore, this technical solution is unsuitable.

[0029] Chemical dissolution of the reinforcing material 14 does not pose a risk of damaging the vane 12, but it has the disadvantage of being time-consuming and expensive.

[0030] The present invention improves upon these drawbacks by proposing a method that includes at least one cooling step in which the reinforcing material 14 is cooled to a negative temperature, and at least one stress application step in which the reinforcing material 14 is subjected to mechanical stress to break the adhesive film 16.

[0031] Cooling of the metal reinforcement 14, which has high thermal conductivity, allows the adhesive film 16 to cool in contact with the metal of the metal reinforcement 14, causing a decrease in its toughness, which changes its ductile mechanical behavior to brittle mechanical behavior. This reduces the mechanical energy input required to break the adhesive film 16, which in turn significantly reduces the risk of deterioration of the vane 12 when the reinforcement 14 is subjected to mechanical stress during the stress application step.

[0032] The change in the mechanical behavior of the adhesive film 16 depends on the adhesive used. Conventionally, the vanes 12 and reinforcing material 14 are assembled using epoxy adhesive, which becomes brittle when it reaches very negative temperatures, as the mobility of the polymer chains in the adhesive film 16 decreases. The cooling step of the method of the present invention allows the adhesive film to become more brittle.

[0033] In a preferred embodiment of the present invention, the cooling step and the stress application step are performed simultaneously. This configuration is not limiting to the present invention, and the stress application can be performed after the reinforcing material 14 has cooled, as long as the temperature does not rise sufficiently for the adhesive film 16 to recover its ductile behavior.

[0034] A tool 30 that enables these steps to be performed is shown in Figures 3 and 4.

[0035] The tool 30 comprises an assembly 32 that is translationally movable along a length L along the free surface 32 of the reinforcing member 14. The assembly 32 can be moved manually. However, within the scope of industrialization of this method, the assembly 32 is mounted on a movable carriage 36 in translational motion.

[0036] Assembly 32 preferably comprises a cooling unit 38 intended to perform a cooling step and a stress application unit 40 intended to perform a stress application step, moving from upstream to downstream in the direction of movement of assembly 30 as indicated by the arrows in Figure 3.

[0037] Thus, any region of the reinforcing member 14 that is cooled by the cooling unit 38 is immediately subjected to the stress of the stress application unit 40 as the assembly 30 is moved.

[0038] The cooling unit 38 comprises a tank 42 for pressurized cooling fluid and an expander 44 configured to receive fluid from the tank 42 and deliver it under a predetermined pressure. The expander is connected to a conduit 46 to which the pressurized cooling fluid is supplied, and this conduit extends in the vicinity of the reinforcing member 14. The end of the conduit 46 is equipped with a nozzle 48 configured to spray the cooling fluid onto the surface of the reinforcing member 14.

[0039] In a preferred embodiment of the present invention, the cooling step is performed by projecting a liquid nitrogen-based cooling fluid onto the reinforcing material 14.

[0040] Thus, the nozzle 48 is configured to spray liquid nitrogen mist onto the surface of the reinforcing material 14.

[0041] Liquid nitrogen is projected at a temperature of -200°C. The adhesive film 16 is cooled by heat conduction through the reinforcing material 14. Therefore, the duration of nitrogen application depends on the thickness and properties of the metal reinforcing material 14, as well as the desired temperature of the adhesive film 16 that causes it to rupture.

[0042] The main advantage of this method lies in the difference in thermal conductivity between the reinforcing material 14 and the adhesive film 16.

[0043] On the one hand, the reinforcing material 14 conducts heat rapidly, allowing the adhesive film 16 to cool quickly. However, the adhesive made of polymer material used in the adhesive film 16 is not very thermally conductive and therefore insulates the vane 12. As an example, applying nitrogen for a few seconds is sufficient to treat a metal reinforcing material less than 1 mm thick.

[0044] Several types of mechanical stresses can be considered during the stress application step, such as stress perpendicular to the chord of the vane. However, preferably, as shown in Figures 3 and 4, the second component, i.e., the reinforcing member 14, is subjected to compressive stress in a direction D substantially perpendicular to the surface of the adhesive film 16.

[0045] This compressive stress is a mechanical stress corresponding to an impact on the surface of the metal reinforcement 14. This compression wave has the advantage of being converted into a traction wave at the interface between the reinforcement 14 and the adhesive film 16 due to the difference in mechanical impedance between the reinforcement 14 and the adhesive film 16. In fact, it is known that a change in mechanical stiffness at the interface between the two materials induces the reflection of a portion of the incident compression wave into the traction wave.

[0046] Generally speaking, compressive stress can be created by vibration means or by projection means. Such vibration means include, for example, ultrasonic hammering means. Projection means include, for example, blasting means.

[0047] In a preferred embodiment of the present invention, the vibration means is an ultrasonic hammering means. For this purpose, the stress application unit 40 includes a chain of components intended to generate ultrasonic hammering.

[0048] These components include a generator 50, which converts an electrical energy source to be supplied to the generator into a sinusoidal electrical signal. This signal is supplied to a converter 52, which converts the sinusoidal electrical signal into a sinusoidal vibrational wave. These vibrational waves are transmitted to an amplifier 54, where they are amplified.

[0049] The amplifier 54 amplifies the vibration waves to a sonotrode 56, which is configured to mechanically transmit the vibration waves. At one end of the sonotrode 56 is at least one transmission finger 58, also called an "indenter," which receives the vibration waves from the sonotrode 56 and is positioned in contact with a reinforcing member 14 of a second component, thereby mechanically transmitting them to the reinforcing member 14.

[0050] Depending on the force of the chain of components, it is possible to have multiple transmission fingers 58, as in the cases of Figures 3 and 4. These fingers 58 not only allow ultrasonic waves to be driven into the leading edge of the reinforcing material 14, for example, but also allow regions 26 and 28 where the reinforcing material joins the extra regions 22 and 24 of the vane 12, for example, to allow the adhesive film 16 to be uniformly separated.

[0051] One or more transmission fingers 58 of the sonotrode 58 apply mechanical stress by ultrasonic hammering in a direction D substantially perpendicular to the surface of the adhesive film 16, as described above.

[0052] Ultrasonic hammering is performed, for example, at frequencies between 10 kHz and 40 kHz.

[0053] As described above, and as illustrated in Figures 3 and 4, the tool assembly 32 allows for both a cooling step and a stress application step to be performed simultaneously. These two actions are performed by the tool 30 within a coverage region C of the leading edge 20 of the vane 12, more specifically by the fingers 58 of the sonotrode 56 immediately after passing through the nozzle 48. Region C has a length l that is shorter than the length L of the leading edge 14 of the vane 12. Thus, the tool 40 is moved along the entire length L of the leading edge 14 of the vane 12, as illustrated in Figures 3 and 4. During movement, the cover region C is first cooled by the nozzle 48, and then, immediately afterward, mechanical stress is applied by the transfer fingers 58. The proximity of the fingers 58 to the nozzle 48 prevents the leading edge 20 from overheating and losing its cooling effect.

[0054] Therefore, separating the vane reinforcement 14 from the vane 12 can be done very easily by simply sweeping the latter with the tool 30.

[0055] This invention simplifies and makes such separation operations more reliable.

Claims

1. A separation method for separating a first machine component (12) from a second machine component (14), wherein the second machine component (14) is joined to the first machine component (12) by an adhesive film (16) along a connecting region (18), the first machine component has a first specific thermal conductivity, and the second machine component has a second thermal conductivity that is higher than the first thermal conductivity. The separation method is characterized by comprising at least one cooling step, in which a cooling fluid is projected onto the second mechanical part (14) so ​​that only the second mechanical part (14) is cooled to below 0°C, the adhesive film (16) is cooled to a desired temperature by heat conduction through the second mechanical part (14) so ​​that the adhesive film (16) becomes brittle, and the first mechanical part (12) is insulated so that it is maintained above 0°C by the adhesive film (16); and at least one stress application step, in which the second mechanical part (14) is subjected to mechanical stress to break the adhesive film (16).

2. The separation method according to claim 1, characterized in that the cooling step and the stress application step are performed simultaneously.

3. The separation method according to claim 1 or 2, characterized in that during the stress application step, the second mechanical component (14) is subjected to compressive stress in a direction (D) perpendicular to the surface of the adhesive film (16).

4. The separation method according to claim 3, characterized in that the compressive stress is performed by a vibration means or a projection means.

5. The separation method according to claim 4, characterized in that the vibrating means is an ultrasonic hammering means and the projectile projection means is a blasting means.

6. The separation method according to any one of claims 1 to 5, characterized in that the cooling step is performed by projecting liquid nitrogen onto the second mechanical component (14).

7. The separation method according to any one of claims 1 to 6, wherein the first mechanical component (12) is a vane made of a composite material, and the second mechanical component (14) is a metal reinforcing material bonded to the leading edge (20) of the vane (12), and the method includes two simultaneous steps: cooling the metal reinforcing material (14) by projecting liquid nitrogen, and stress application step in which the metal reinforcing material (14) is subjected to mechanical stress by ultrasonic hammering in a direction (D) perpendicular to the surface of the adhesive film (16).

8. The separation method according to claim 7, characterized in that the separation is carried out by a tool (30) that has a length (l) shorter than the length (L) of the leading edge (20) of the vane (12), enabling the simultaneous execution of two steps: cooling and stress application in the covering region (C) of the leading edge (20) of the vane (12), wherein the tool (30) is moved along the entire length (L) of the leading edge (20) of the vane (12).

9. The separation method according to claim 7, characterized in that the liquid nitrogen is projected at a temperature of -200°C, and the ultrasonic hammering is performed at a frequency of 10 kHz to 40 kHz.

10. A tool (30) incorporated into a method according to any one of claims 1 to 6 for separating a first machine component from a second machine component, comprising an assembly (32) that can translate along the free surface of the second machine component, wherein the assembly (32) - A stress application unit (40), A generator (50) that converts power to be supplied to the generator (50) into a sinusoidal electrical signal, A converter (52) that converts a sinusoidal electrical signal into a sinusoidal vibration wave, An amplifier (54) that amplifies vibration waves, A sonotrode (56) configured to transmit vibration waves, At least one transmission finger (58) positioned in close proximity to the second mechanical component (14) and adapted to receive vibration waves from the sonotrode (56) and mechanically transmit them to the second mechanical component (14), A stress application unit that continuously provides, - Cooling unit (38), Pressurized nitrogen storage tank (42), An expander (44) configured to receive nitrogen from a tank (42) and supply this nitrogen under a predetermined pressure, A conduit (46) extending near the second mechanical component (14) is supplied with pressurized nitrogen by an expander (44), A nozzle (48) is positioned at the end of the conduit (46) and configured to spray liquid nitrogen onto the surface of the second mechanical component (14), A cooling unit (38) that has a series of these, A tool (30) characterized by having the following features.

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