EP1408177A1 - Apparatus for removing putty - Google Patents

Abstract

The tool has a mastic removing tip (28) with a shaft (36) and a head (38) reciprocated by a pneumatic vibration motor (32) operating at a frequency of 120Hz and enclosed in a casing (30). The head, which has a bevelled end with a preferable angle of 30 deg, is made from a polymer material with an optional filler of carbon or glass fibres. The tool is stowed in a container with spaces for cables and a compressed air connector and regulator.

Description

The present invention relates to a demixing device, in particular for the repair of joints in aircraft tank structures.

The invention also covers the intervention container.

Reservoirs, in particular in aircraft, are directly constituted by free volumes in the wings.

Indeed, the wings are made from a structure composed of ribs, of stiffeners, with passages of the different organs but most of the structure is empty. Plates are then reported on this structure in kind of realize a closed volume, with the adapted forms and presenting the mechanical characteristics necessary for the flight.

The volume is thus mechanically closed but it is not waterproof since the plates are screwed or riveted and if physical continuity is ensured, the joints between the plates are not hermetic.

If one wishes to use these volumes thus realized to constitute reservoirs of fluids and in particular of fuel, it is necessary to quench the joints and all the passages of fastening means such as aeronautical screws or rivets.

This seal is obtained by depositing cords of mastic on all joints and mastic stubs on all through-passages, including fastening means.

This putty is deposited by means of a pistol in more or less viscous form then polymerized in situ at room temperature with a suitable hygrometry.

If the temperature is too low or to speed up the operation, it is possible to use a thermoreactor marketed especially under the name "SUNAERO" so as to emit infrared radiation located in the absorption zone of the types of putty retained. The polymerization is thus accelerated.

This sealant deposit is necessarily made once the wing is complete. However, given the number of reinforcing elements, cross stiffeners and others equipment, and taking into account the dimensions of the wings, in particular in thickness, there is little room for an operator to move and even less to work.

It is indeed necessary to access all the points of passage of means of fixation and to all joints, exhaustively and some are very difficult access.

For the removal of a cord with a pistol, if the operation is delicate, it requires only reasonable physical effort, the difficulty resulting rather from the uncomfortable position of the operator and the necessary accuracy.

These mastics used are adapted to resist fuel and are very sophisticated because they resist significant differences in temperature, have certain qualities of hardness while allowing flexibility sufficient to prevent breakage during movements and vibrations experienced by the different rooms.

The adhesion power is in any case very important to remove any risk of detachment. Very rigorous procedures must be put in place work knowing that the mastic adheres not on the metal but on the layers of covering and protection paint whose different parts are coated.

Nevertheless, defects may occur and in the course of Cracks appear and cause fuel leaks.

This problem often occurs in the most stressed areas as the root of the wings or the right of the support structure means of propulsion.

The operators remedy these defects during systematic visits of maintenance or specific interventions, if necessary.

During this repair step, first flush the wing volume concerned, vent it and locate the leak. Access to the interior volume is made by a manhole in the wing from which the hatch must be removed following specific procedures.

To ensure repair, the used sealant must be removed from the affected area and replace it with new putty.

This is where there are significant problems that the present invention propose to solve in the best way possible.

Indeed, the mastic is composition even with a power of adhesion very high, power that gets stronger as time goes by. In addition, the mastic hardness increases with aging.

As has been explained, the access conditions for certain areas are delicate and to remove the putty, it is necessary this time to spend an energy i important.

Fortunately, leak detection procedures with localization a leak can be used to circumscribe the area and limit the extent of the repair of the waterproofing.

The solution is currently a mechanical scraping process using polycarbonate spatulas for example, which are sharpened and manipulated by operators in order to better scrape the areas concerned. This operation is therefore manual. Electrical appliances or likely to generate sparks are prohibited since even after ventilation, the atmosphere can stay punctually explosive.

It should also be noted that only chips are allowed in order to be able to recover and remove them from the body of the wing unlike sawdust sawdust that could generate sanding. Sawdust or residual dust could then foul the kerosene filters and are therefore prohibited.

Similarly solutions have been experimented with chemical solutions. The products used must be neutral for the operator but also for constituent materials of the wing. Moreover, after having used them, we notice at best, we get a softening of the mastic that we still need remove mechanically.

As for this cleaning with chemical solutions, it remains delicate because it is impossible to determine when the product stops working, which disrupts the filling of the tanks.

Ultrasound like water jets require too large equipment and it is necessary to be able to realize systems of simultaneous recovery of the waste for it necessarily produces projections. In addition, water penetration in the interpositions of structure can generate points of corrosion difficult to detect.

Trials were conducted with cryogenic products to make the brittle mastics hoping to facilitate manual operation. But there are health and safety issues with operators. The effectiveness of a such method is very limited.

Another constraint is due to the fact that the surfaces are coated, usually a protective primer that must be left on the metal. In addition to this delicate coating, it is imperative to avoid any scratching of the metal would be a potential breakthrough. As the material is usually an aluminum alloy, the stripes can be unfortunately easily generated.

The area must be thoroughly cleaned to follow the procedure of remixing and obtain a good seal after removal of the new cord or putty block to polymerize. The duration of this phase represents substantially half of the time required for the complete intervention.

These constraints, associated with the working conditions for the operators, impose a more comfortable solution for operators and more effective for operators. Such a solution is sought by the operators for many years.

The intervention of the operators is long or the immobilization of an aircraft is extremely expensive. When repairs are made in masked time during maintenance, this is less problematic although expensive in the case of a punctual intervention on a poorly equipped airport, urgently, far from the basics, the financial loss can be very high.

The present invention overcomes the above disadvantages and the adapted container authorizes rapid interventions anywhere, with quality of intervention compatible with the needs and standards of aeronautics.

• figure 1, une vue d'une portion d'aile d'aéronef avec des joints et des moyens de fixation recouverts de mastic,
• figure 2A, une vue de détail d'une vis aéronautique, en perspective,
• figure 2B, une vue en coupe de la vis de la figure 2A,
• figure 3A, une vue du dispositif selon l'invention,
• figure 3B, une vue agrandie d'un embout,
• figure 3C, une vue de détail d'une variante d'embout, et
• figure 4, une vue d'un container d'intervention.

The present invention is now described with reference to the appended drawings which represent a preferred but non-limiting embodiment of the device of the present invention, the various figures representing:

• FIG. 1, a view of an aircraft wing portion with seals and fixing means covered with mastic,
• FIG. 2A, a detailed view of an aeronautical screw, in perspective,
• FIG. 2B, a sectional view of the screw of FIG. 2A,
• FIG. 3A, a view of the device according to the invention,
• FIG. 3B, an enlarged view of a mouthpiece,
• FIG. 3C, a detail view of a tip variant, and
• Figure 4, a view of an intervention container.

FIG. 1 shows an aircraft wing portion 10 with a zone complex comprising a joint with three plates 12-1, 12-2 and 12-3 forming a angle, the three cords 14-1, 14-2 and 14-3 of Putty 14 meeting at intersection.

This schematic representation also shows a series of means 16 of fixing plates, in this case aeronautical screws 18.

These screws, as can be seen in FIGS. 2A and 2B, pass through holes 20 that must be sealed.

Therefore, the solution consists of a putty deposit 14, in the form of a stud 14-4 covering the assembly of the screw 22 and its nut 24. Note that this stud extends beyond the nut to adhere to the surface of the plate.

These deposits of putty 14 perfectly marry the surfaces on which they are deposited, which makes the withdrawal all the more complicated.

It is recalled that aluminum and its alloys which are aeronautical materials par excellence, corrode under the action of oxygen in the presence of a medium acid, water, chloride, which requires the coating of the whole of the structure by a barrier primary that must necessarily be preserved during demoulding operations.

As for scratches, we must ban them because aluminum and its alloys have a particular behavior. A scratch is indeed a beginning of rupture; the corrosion focuses on this specific point and develops right from this point low. This concentration of corrosive action is a danger.

One of the important problems is therefore the choice of the disbonding tool because it must also determine a material that is as resistant to wear as possible for reasons of economy but for reasons of efficiency because it is not possible for the operator to constantly change tools or to see the quality of this tool during work, the duration of intervention would be increased proportionally.

As for the inadvertent withdrawal of primary, it can be remedied by the laying of a new coating on the degraded area but in this case, the duration intervention is elongated, which is undesirable.

The present invention relates to a device comprising means 26 for placing vibratory reciprocating motion and a tool 28 integral with these means.

The means 26 for vibratory reciprocating movement comprise a body Including a motor 32 and a mandrel 34 adapted to receive said tool 28.

Advantageously, the motor is of the pneumatic type and the connection is a fast connection of the type marketed under the name "STAUBLI". The vibratory frequency is around 120 Hz to give a order of idea.

The tool 28 comprises in this embodiment a rod 36 and a head 38.

The rod is intended to be mounted in the chuck 34 while the head 38 is the body in contact with the putty and the surface of the wing, intended to walk to the interface.

This head must be made of a material whose hardness is sufficient to cut mastic chips and to resist wear but not too much to not cause scratches under the effects of the vibratory alternating movement.

These two parameters being antithetical, we understand why so far such a device has not been developed because the person skilled in the art is dissuaded from resort to such means.

Many tests have been done and some materials particularly well adapted. It is then necessary to check the performance of these tools, which may allow guidance on the final choice for this or that user.

Among the materials giving the best results are the polyetheretherketones known as PEEK (polyetheretherketone), polyoxymethylenes, polyetherimides or epoxy resins.

With regard to performance, preference is given to polyetheretherketones loaded with carbon or fiberglass.

When the load is carbon, although the quantities are very limited, the aviation industry remains reluctant because carbon creates corrosion in contact with aluminum and its alloys.

The preference is rather for polyetheretherketones loaded with 30% fiber of glass.

With regard to these materials, the shape of the area should also be analyzed work of the head.

The simplest and most used form is the bevel shape, especially with a reciprocating vibratory motion in the working axis.

Cutting angles of this bevel are analyzed 30 °, 45 ° and 60 °, symmetrical and asymmetric

The angle of 30 ° in symmetrical or asymmetrical gives satisfaction by generating very little dust, producing good quality chips, without generating rebounds harmful to operators under vibratory movements alternative.

This is the representation that is made in Figure 3B.

FIG. 3C shows a so-called special head as it can be realized, especially for certain angles even more difficult to access. The shapes are then guided by the applications.

Practical tests have shown that the operator does not need to exercise a significant effort on the device, a pressure of a few bars is sufficient to hold the tool in abutment on the sealant, vibrating oscillatory movement ensuring the detachment of the sealant or the formation of chips.

In any case, a pressure control valve is provided pneumatic when it comes to this type of power source in order to get the adequate pressure at the end of the tool.

It should be noted that the pneumatic way is preferred because the risks of leakage do not have consequences like that could be the case with a fluid hydraulic.

In addition, which says hydraulic also says specific center while the compressed air is available in any workshop, even the least well equipped.

An electric motor is banned because of the metallic environment driver and possibly explosive atmosphere.

The invention also provides an intervention container 40, adapted to provide the overall demixing service.

Such a container 40 comprises at least one device according to the present invention with a reserve 42 of tools considered consumable, flexible adapted in particular a hose 44 for connection to an air source 46 local tablet when not supplied, a housing 48 regulating the delivered air pressure, a suction system 50 venturi connected on the same source of compressed air supply.

This container may also include individual protections such as glasses, gloves, masks and hearing protection.

Thus, during an intervention, the operator moves to the airport that has received the immobilized aircraft with this container. All he needs is a source of compressed air to connect its devices.

After the preparation of use of the tanks such as emptying, degassing, opening of the manhole, leak detection, operations which can be conducted prior to his arrival, he is sufficient access through the manhole corresponding to the area concerned.

He carries with him, in the wing, the complete device connected to the air source under pressure after having adjusted the pressure, the suction hose 50 and possibly some spare tools.

To give an order of magnitude, the life of a tool is estimated at about half an hour.

The operator actuates the control lever by applying with a moderate effort the head against the block or bead of mastic to be removed, thus generating shavings.

After doing some or all of the work, vacuuming these chips keeps the area clean.

The working conditions for the operator are greatly improved and the speed of execution is incommensurate with an operation of manual spreading.

Even when the area is very difficult to access, the operator has no effort important to provide can reach it and exert sufficient pressure on the device to achieve the desired result.

In addition, the working time is much shorter because the frequency of vibration allows the operator to generate chips as with a chisel to wood.

The head comes into contact with the primary and removes the sealant without degrading this because of the nature of the material, the angle of the head, the frequency and the power of vibrations. The thickness of putty intervenes only little since the power of the tool allows to cut the sealant in the mass if necessary, including aged mastic. The operator therefore performs a reduced number of passes.

At the end of the removal of the putty in the area concerned, it is necessary to remake, this which is not an operation concerned by the present invention but which is indicated for information.

This step consists in a simplified way to ensure cleaning of the area concerned with a solvent to have a perfectly clean surface.

The bead or mastic pads are made with a dispensing gun. This removal is followed by an accelerated polymerization of this mastic by means of a heating with infrared radiation.

Sealing being achieved, it is possible to repeat a leak test in particular by means of the helium test equipment described in the application French Patent No. 02 07554 in the name of the same holder before filling in new the tank.

There are commercial tools to generate movements vibratory alternatives but they remain relatively heavy.

Specific tools with a material body should be developed lightened without this tool being too light because it is necessary nevertheless a some inertia to ensure anti-recoil and efficiency at each vibration, also limiting the efforts of the operator.

In addition to the device according to the present invention, it may be useful to developing a variety of finishing brushes, including rotary ones with fibers with characteristics similar to those of the heads. In this case generated dust remains very limited since it concerns finishing and means suction can allow simultaneous suction.

Claims (10)

Device for removing the grout, in particular for repairing joints in aircraft tank structures, characterized in that it comprises means (26) for vibratory reciprocating movement and a tool (28) integral with these means. Dispensing device according to claim 1, characterized in that the means (26) of vibratory reciprocating movement comprises a body (30) including a motor (32) and a mandrel (34) adapted to receive said tool (28). Dispensing device according to claim 1 or 2, characterized in that the motor is of the pneumatic type with a vibratory frequency of 120 Hz. Dispensing device according to claim 2 or 3, characterized in that the tool (28) comprises a rod (36) intended to be mounted in the mandrel (34) and a head (38) intended to be in contact with the surface to be unmasked. Dispensing device according to any one of the preceding claims, characterized in that the head is made of a material chosen from polyetheretherketones, polyoxymethylenes, polyetherimides or epoxy resins. Dispensing device according to claim 5, characterized in that the material is a polyetheretherketone loaded with carbon or fiberglass. Dispensing device according to claim 6, characterized in that the material is a polyetheretherketone loaded with 30% glass fibers. Dispensing device according to any one of claims 4 to 7, characterized in that the head is bevel-shaped and has an angle of 30 °, 45 ° or 60 ° preferably 30 °. Container (40) comprising at least one device according to any one of preceding claims with a reserve (42) of tools, adapted hoses in particular a hose (44) for connection to a source (46) of compressed air, a housing (48) for regulating the delivered air pressure. Container (40) according to claim 9, characterized in that it comprises a venturi suction system (50) connected to the same source of compressed air supply.

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