WO2006097134A1 - Shoe and device for stripping surfaces having a curvature by directed spraying a discharge of a flow of particles - Google Patents

Abstract

In order to eliminate, during stripping, the losses of particles and to prevent their being redeposited, the invention provides for a stripping shoe comprising at least one spray nozzle (11) with longitudinal axis (XX'), an input adapted to be connected to an intake of a fluid supplying pipe and an output located proximate a so-called active zone of the surface to be treated. Said shoe forms a substantially sealed chamber (12), except for a surface having an opening (35) adapted to be applied opposite the surface (S) to be stripped while observing the curvature of said surface, and wherein extend the spray nozzle (11) and the suction pipe (25) connected to a vacuum generator (30), the nozzle and the suction pipe being substantially inclined in opposite direction relative to the open surface (35). The longitudinal axis (XX') of the nozzle (11) and a plane (T) tangent to the active zone form a leading edge (a) ranging between 35° and 60°, preferably between 40° and 55°, typically between 45° and 50°. The shoe can be connected to a functional assembly (100) whereto the flexible pipes (9, 19, 27) are connected, said assembly (100) further comprising a device (15, 16) for ionizing air, having an output connected to a conduit (17) which terminates in a channel (22) inside the chamber (12) emerging on the opposite side of the suction channel (25).

Description

 SABOT AND SURFACE CUTTING MACHINE

POSSIBLE TO PRESENT A CURVATURE BY PROJECTION

AND ORIENTED EVACUATION OF A PARTICLE STREAM

The invention relates to a stripping shoe made by directed projection and evacuation of a particle stream for stripping surfaces that may have a certain curvature. It also relates to a stripping machine equipped with such a shoe.

A known pickling method consists in projecting on the surface of an object to be treated a two-phase flow, namely a flow of fluid, generally a gaseous flow, containing solid particles, in order to clean the object by erosion of the particles. surface particles caused by the multiple impacts of solid particles, this operation therefore consisting of stripping.

The biphasic flow is forcefully projected by means of a nozzle whose position must be of high precision with respect to the surface of the object to be treated, both in distance and in inclination, according to the work to be done.

Depending on the size and characteristics of the objects to be treated, the operation takes place in a closed cabin or in the open air.

The use of a cabin makes it possible to avoid the dispersion in the atmosphere of the solid particles that have been projected on the surface to be stripped, various means being used for the recovery of these particles and, possibly, their reuse.

But it is obviously possible to use a cabin for objects of relatively small dimensions and easy to handle. When objects are large, such as aircraft surfaces, the projected particles can not be captured effectively and a large proportion of it is lost to the atmosphere.

In addition to the actual pollution, these particles form a dust that tends to be deposited on the entire environment and this obviously has serious drawbacks.

The object of the present invention is both to suppress the losses of particles and to prevent them from being deposited either on the surface or on the parts of the projection device, so that the surface of the object is not only pickled but perfectly clean, which allows to cover it without further treatment with paint or any coating. The invention also aims to recover the particles from the stream for recycling.

In addition, the object of the invention is to allow the etching of a surface having a slight curvature and defects without slowing it down.

In order to achieve these goals, or at least one of them, the invention proposes to form a shoe according to an open envelope adapted to the surface to be treated and to specifically guide the projection and evacuation of the flow at look at the surface to be treated. More specifically, the present invention relates to a projection and evacuation stripping shoe oriented a flow of fluid-borne particles for stripping surfaces that may have a certain curvature, having a projection nozzle extending along a longitudinal axis, an input capable of being connected to a supply inlet of particle-laden fluid supply and an outlet situated close to a so-called active zone of the surface to be treated, called a pickling front, the hoof forming an enclosure substantially watertight, with the exception of a main face having an aperture adapted to be applied to the surface to be etched so as to respect the possible curvature of said surface, and in which extend on the one hand the nozzle of projection and on the other hand a suction pipe connected to a vacuum generator, the nozzle and the suction pipe being substantially inclined in opposite directions with respect to the open face, respectively for projecting and discharging the charged fluid after projection, enclosure in which the longitudinal axis of the nozzle and a plane tangential to the active zone form an angle of attack of between 35 ° and 60 °, preferably between 40 ° and 55 °, typically between 45 ° and 50 °.

According to preferred embodiments: adjustment means are provided for adjusting the angle of attack of the solid particles and / or the distance which separates the nozzle outlet from the surface to be treated; - The enclosure is formed of several parts articulated together by transverse pivots, to adjust their relative inclination to match the curvature of the surface to be treated;

- A central part of the chamber is provided with a transverse rolling member located in the middle part of this part to remain in contact with the surface to be treated;

the enclosure is maintained at a predetermined distance from the surface to be treated by rolling members, in particular rollers, capable of being placed and held by an operator in contact with the surface to be treated in order to roll on this surface during a relative displacement between said enclosure and said surface, these members being able to ensure a tight and mobile seal during the relative movement;

- Each rolling member is associated with a cylindrical brush connected to a rotating drive mechanism and having outer active elements of particle recovery in contact with the corresponding roller, these active elements may also be in contact with the surface to be treated;

the drive mechanism of each rotary brush is mono directional, with a view to printing with a brush a direction of constant rotation and independent of the corresponding rolling direction;

- The direction of rotation of each brush is such that any brush portion located closer to the surface to be treated moves to the active area;

each roller and each brush are partially engaged in a fairing except in the areas where each brush is in contact with the corresponding roller and possibly with the surface to be treated;

- An auxiliary duct is formed in the chamber and connects on the one hand the area where a brush is in contact with the corresponding roller and, on the other hand, the suction line;

the enclosure is surrounded by a peripheral frame associated with a means of pressure, pressure, hydraulic or electromagnetic means, which constantly urges it towards the surface to be treated beyond the walls of the enclosure and which is provided with a filter means in contact with the surface to be treated, the filter means being able to let air through without passing the particles of the flow;

the filter means is a peripheral brush whose active elements are bristles, a synthetic foam, a natural foam or a combination thereof;

- The enclosure contains at least one deflector attached to the transverse edges of the open bottom portion and inclined to the plane of the open bottom.

The invention also relates to a pickling machine comprising the preceding pickling shoe and a functional assembly to which the flexible hoses are connected, the enclosure thus being capable of movement relative to this assembly, these flexible hoses being adjustable in length. by drums or the like. This assembly also comprises a device for the ionization of air, having an output connected to a conduit which leads to a channel inside the enclosure opening opposite the suction pipe, so that the ionized air reaches the particles of the flow and is evacuated by suction in said suction line.

Other particular embodiments of the invention are defined in dependent claims and other characteristics and advantages will appear on reading the detailed description below, made with reference to the appended figures which represent respectively:

• Figure 1, a schematic view of a pickling machine according to the invention; • Figure 2 is a schematic sectional view of an enclosure of a shoe according to the invention, illustrating its operation when the shoe is effectively stripping the surface of an object;

• Figure 3, a schematic sectional view of the same chamber when the shoe is in operation but the stripping action is interrupted, in particular for a lateral shift of the enclosure on the surface to be treated; • Figure 4, a schematic view of the shoe according to the invention, in a position where it is remote from the surface to be treated, especially in approach thereof;

• Figure 5, a view similar to the previous one, showing the shoe according to the invention coming into contact with the surface to be treated;

• Figure 6, a view similar to the previous one, showing the abutment of the shoe according to the invention, in order to establish a sealed contact between it and the surface to be treated; and

FIGS. 7a to 7c, stripping edge profiles showing a stripping nozzle speed that is too high (FIG. 7a) or too weak

(Figures 7b and 7c, Figure 7c being a sectional view Y'Y according to Figure 7b) with respect to the particle projection speed.

With reference to FIG. 1, a machine according to the invention comprises a reservoir 1 containing a certain quantity of solid particles having a particle size adapted to the work to be performed, which depends, in particular, on the physicochemical characteristics of the products to be removed, in particular paint in the illustrated examples, as well as characteristics of the support that is to say the surface of the object to be treated, an aircraft cell in these examples. This tank 1 is fed by any known means from an inlet pipe 2 and is pressurized and closed, so that the inlet pipe 2 does not discharge the solid particles by simple gravity but cyclically when the quantity of particles that the reservoir 1 contains reaches a lower limit. Then, the tank 1 is depressurized and is filled from the supply line 2, the corresponding valve controls can obviously be automatic.

At the base of the tank 1, there is an outlet duct 3 which leads to a connecting flange 8 for a flexible pipe 9 which terminates in a connection 10 making it possible to connect the flexible pipe 9 to a rigid nozzle 11. This nozzle 11 is engaged in a housing of an enclosure 12 which maintains it in a precise position, as will be explained in detail below. The machine also comprises an air ionization chamber 15 connected to a high voltage direct current power supply 16 and connected to an outlet 17 terminating in a connecting flange 18. A flexible pipe 19 is connected to the flange 18 and leads to a connector 20 for connecting the flexible pipe 19 to the endpiece 21 of an internal channel 22 to the enclosure 12.

Opposite the central part of the enclosure 12 is a suction pipe 25 at the external outlet from which there is a connection 26 for a flexible pipe 27 which is attached to a connection flange 28 to which a pipe follows. 29 on which is placed a device 30 called "cyclone" which simultaneously separates between on the one hand the reusable solid particles which return to the tank 1 by a pipe 31 and on the other hand the waste and the fragmented solid particles too fine particle size, for evacuation through a pipe 32. A vacuum pump (not shown) establishes a vacuum in the pipe 29 for the suction of solid particles according to the arrow F1. Any other device for inducing movement of the particles in the direction of arrow F1, such as a fan, may be added or substituted for the vacuum pump.

A mixed line circumscribes a space which schematizes a functional assembly 100 which may be a mobile or fixed installation, or a self-contained apparatus and to which the flexible hoses 9, 19 and 27 are connected, the enclosure 12 thus being able to move relative to each other. to this assembly 100, for which reason the connecting pipes of the enclosure 12 are flexible hoses which, in addition, can be adjustable in length by well known means such as reels (not shown). The enclosure 12 is substantially sealed, with the exception of an open bottom portion 35 capable of being applied to the surface S of the airframe A. In the enclosure 12, on the one hand, the nozzle projection 11 and on the other hand the suction pipe 25 connected to the vacuum generator 30, substantially inclined relative to the open bottom part 35, respectively for projecting and for discharging the fluid after projection.

The enclosure 12 is positioned on the surface S so that its open central bottom portion 35 is applied in a sealed manner, but simultaneously the inside of the chamber 12 must be depressed to prevent any projection of solid particles from the chamber 12, any dust or solid particle suspended in the immediate vicinity of the chamber 12 being biased in the direction of the outside towards it and not the other way around.

The open part 35 allows the surface S to be accessible to a stream of solid particles 36 set in motion by the combined action of the pressurization of the tank 1 and the suction of the vacuum pump (not shown) according to the arrow F1 , the solid particles contained in the tank 1 moving along the arrows F2 and F3 in the pipe 3 and in the pipe 9 to reach the nozzle 11 from which they emerge at a short distance from the open central portion 35, to be projected with force on the surface S. Thus, the channel 22 inside the chamber 12 opens out opposite the suction pipe 25, so that the ionized air reaches the particles of the stream 36 and is evacuated by suction in said pipe. suction 25.

The particles of the flow 36 bounce off this surface S and carry with them fragments of the paint layer K covering the surface S of the airframe A, the whole being sucked along the arrow F4 by means of the cyclone 30, by the 25, the flexible pipe 27 and the pipe 29. The solid particles are thus removed immediately after being active by shock and friction on the surface of the aircraft cell A, without spreading in the atmosphere, and therefore without cause pollution.

It should be noted that the flow of air sucked according to the arrows F1 and F4 by the cyclone 30 is greater - for example of the order of 80 to 90 cubic meters per minute (πvVmin) - that the flow of air admitted by the nozzle 11 - for example of the order of 2 to 3 m ³ / min - to create a vacuum inside the chamber 12 and deliberately create "leaks" of ambient air to the interior of the enclosure 12. This ensures that particles can not be misplaced and accidentally travel to the ambient air, which eliminates any risk of pollution or presence of dust in the vicinity of the work site. The mobile enclosure 12 and its components will be described in detail, with reference to FIGS. 2 to 6, in which the same elements as those of FIG. 1 bear the same references.

The chamber 12 is determined by two longitudinal walls (only the wall 41 is visible in Figures 2 and 3) and by transverse walls 42 and 43 forming a rectangular contour belt.

The upper part of the enclosure 12 is closed by different parts more or less careened and receiving the nozzle 11, the nozzle 21 and the suction pipe 25. The central lower part 35 is open and laterally limited by the longitudinal walls ( the wall 41 and its opposite wall parallel not visible in the drawing) and transversely by rolling members which are constituted here by two rollers 44 and 45 whose surface must be sufficiently flexible to ensure an elastic and sealing contact with the surface S For this, the rollers 44 and 45 may be made entirely of a material such as an elastomer, or metal covered with elastomer, or in the form of an inflatable flexible enclosure.

The enclosure 12 thus rests on the object to be treated by the rollers 44 and 45 and these roll on the surface S when the enclosure 12 is moved. The running gear can be either kinematically associated with a motor drive device, or mounted free on their bearing axis.

The enclosure 12 is thus maintained at a predetermined and invariable distance from the surface S by the rollers 44, 45 able to be put and held by an operator in contact with the surface S of the airframe A in order to ride on this surface. surface S during the relative displacement between said enclosure 12 and said surface S.

Thus, the stream 36 strikes the surface S, removes the coating by very small fragments, and is sucked by the pipe 25 without loss or leakage of solid particles into the atmosphere.

On the other hand, the solid particles being very fine, some of them can escape from the suction current and infiltrate under them. rollers 44 and 45, for which reason each is associated with a rotating cylindrical brush 46 and 47, respectively, connected to a rotary drive mechanism and having external active elements for collecting particles in contact with the roller 44 , 45 corresponding. The active elements are selected from the group consisting of bristles, synthetic foam, natural foam and a combination thereof. The bristles rub on the rollers 44 and 45 to remove any solid particles that could have infiltrated under these rollers 44 and 45.

So that the action of the brushes 46 and 47 is the best possible and there is no loss of air, each roller 44, 45 and each brush 46, 47 are partially engaged in a fairing respectively 44a, 45a and 46a, 47a which individually wraps them except opposite areas where each brush 46, 47 is in contact with the corresponding roller 44, 45.

According to a preferred embodiment, the outer active elements are also in contact with the surface S to improve the collection of solid particles. In this case, each roller 44, 45 and each brush 46, 47 are partially engaged in a fairing, respectively 44a, 45a and 46a, 47a, which surrounds them individually except in the areas where each brush 46, 47 is in contact with the roller 44, 45 corresponding and with the surface S.

This brushing action assumes that there is a relative movement between each roller 44, 45 and its brush 46, 47 and as the rollers rotate according to the relatively slow speed of the displacement of the enclosure 12, the brushes 46 and 47 are rotated at a speed much higher than those of the rollers 44, 45, for example of the order of 100 revolutions / minute, and always in the same direction, regardless of that of the displacement of the enclosure 12: from front to back "or" from back to front "by considering the longitudinal axis of the enclosure 12. Thus, the drive mechanism of each rotary brush 46, 47 is monodirectional, in order to print at the brush 46, 47 a direction of rotation constant and independent of the direction of rolling of the transverse roller 44, 45 corresponding. The rotational direction of each brush 46, 47 is such that the portion of the brush 46, 47 closer to the surface S is moved to the active area. In the drawings, assume the right front and the left rear, so that the arrow F5 of Figure 2 indicates a displacement of the chamber 12 forward.

In this direction of movement, the roller 44 rotates clockwise according to the arrow F6 and the brush 46 rotates in the same direction along the arrow F7, but at a higher speed, and while letting pass the air from the outside to the inside of the enclosure 12. It pushes inwards and upwards the solid particles that could have accidentally passed under the roller 44 (in particular by adherence with it) and directs them towards the mouth of an auxiliary conduit 48 opening into the suction pipe

25, so that these solid particles are sucked into the flow 36 in motion, towards the cyclone 30.

With this structure, the solid particles mislaid out of the main stream 36 are recovered and returned to the suction whereby even these solid particles are prevented from dispersing into the atmosphere and any pollution is avoided.

It is known that the stripping of the coated surfaces can create a phenomenon of static electricity, in particular because of the friction due to the impacts of the solid particles on the surface S, and that this superficial static electricity has the adverse effect of attracting and retain solid particles of low density, which reduces the recycling efficiency.

This phenomenon can also pose serious problems when moving the shoe because charged particles that remain on the surface S can cause, on the one hand, scratches on the lower surface, and on the other hand, prevent the user from good distinguish the edge of the stripping band.

To overcome this problem, ionized air is sucked according to the arrows F8 by the vacuum prevailing in the chamber 12, thus arrives through the flexible pipe 19 and the channel 22 and passes through all the spaces that remain between the various organs and internal parts, up to the surface S, in the immediate vicinity of the arrival of the flow 36 leaving the nozzle 11.

This ionized air puts at the same electric potential the air which contains the solid particles and the surface S of the cell A itself, so that the solid particles are prevented from adhering to this surface S. Their detachment and aspiration along the arrow F4 are favored. The ionizer air also allows a better takeoff, by the brush 47, particles that could have passed under the roller 45. Thus, when the shoe is passed, the edge of the stripping band is clean and allows a careful adjustment of the roller when stripping the next strip.

The roller 45 rotates in the same direction as the roller 44, according to the arrow F9, since both roll under the effect of the displacement of the entire enclosure 12. On the other hand, the brush 47 rotates in the opposite direction, according to the arrow

F10 and, in the same manner as described above, the brush 47 rotates fairly fast, traps the solid particles that could have passed under the roller 45, then propels them into the stream of ionized air, according to the arrow F8, while by allowing the air to pass easily from the outside to the inside, to ensure the continuity of a current of air set in motion by the suction due to the action of the depression by the vacuum pump.

Maintaining the depression inside the chamber 12 assumes that there is a seal between the open central portion 35 of the chamber 12 and the cell A, but that there remain spaces allowing the ambient air to flow from the outside to the inside of the enclosure, as explained above about rotating brushes 46 and 47.

For this, the shoe of the invention is completed by an outer peripheral frame 50 formed of a profile which has a skirt 51, a return 52 and a guide 53, and slidably mounted around the enclosure 12. This structure forms a continuous corridor 54 surrounding the enclosure

12 and below which are fixed brushes 55 providing a contact without constraint with the surface S of the cell A, which allows to apply the invention to surfaces and fragile objects to be treated.

Above the frame 50, a peripheral support 56 is fixed to the walls of the enclosure. This support serves as a stop for springs 57 which permanently urge the frame 50 towards the surface S. The peripheral frame 50 is provided with a filter means in contact with the surface S, the filter means being adapted to let the air pass without letting the particles of the flow pass. The filter means is a lower peripheral brush 55 whose active elements are selected from the group consisting of bristles, synthetic foam, natural foam and a combination thereof. The corridor 54 receives the rare solid particles that have escaped the direct suction of the pipe 25, and the brushes 46 and 47, which accidentally penetrate but are quickly taken up by the permanent air flow that exists between the outside of the enclosure and the interior, as explained above.

The operation of the machine which has just been described is as follows. The chamber 12 is placed on the surface S of the airframe A, in the desired orientation so that the longitudinal displacement of the chamber 12 allows to go through, in successive passes, the entire surface to be stripped.

At this time, the seal is ensured between the surface S and the open central portion 35 of the enclosure 12. The cyclone 30 is then triggered, and the combined action of the depression generated downstream by the latter and the pressure generated upstream in the tank 1 causes the arrival of the biphasic fluid through the nozzle 11 and forces the solid particles of the stream 36 to hit the paint layer K of the surface S by the central opening 35 and then start immediately, almost instantly, by suction in the pipe 25.

According to various parameters, such as particle size of the solid particles, state of the coating to be removed, characteristics of the surface S and the object to be treated, etc., the enclosure 12 is moved more or less rapidly.

The symmetry of the chamber 12 and the elements which it carries allow its longitudinal displacement in the two opposite directions according to the arrow F5 (FIG. 2) and in the opposite direction, being recalled that with the example represented in this FIG. the conventional sense of displacement is that of arrow F5.

In order to observe in real time the active zone, that is to say the pickling front, during treatment, the enclosure 12 has a control window situated above the open bottom 35 and provided with a transparent waterproof wall 60 through which the quality and progress of the work can be examined, for example visu. According to one embodiment, the stripping shoe comprises an observation device 61, such as an optical or digital camera, located opposite the window, outside of it.

To improve the quality of the observation, the stripping shoe comprises a lighting device for the active part, the lighting device being chosen from the group consisting of visible wavelength illumination, UV illumination, grazing lighting and polarizing lighting.

Generally, the outflow of stripping nozzles of the state of the art has a heterogeneity of energy. For example, some nozzles create a flow whose particles are faster outside the center of the flow. Thus, when the pickling nozzle advances too rapidly the pickling front FD has a profile P1 in C as shown in FIG. 7a, and when the nozzle advances too slowly, the pickling front FD has a P2 profile in D as represented Figure 7b. In the latter case, Z grooves may appear on the edges of the etched portion, as shown in the sectional view Y'Y of Figure 7c, thus materializing the stripping of a lower layer. This is unacceptable for some applications where only one layer must be stripped.

To overcome this problem, the rollers 44, 45 are kinematically associated with a motor drive device and the observation apparatus is connected to a computer comprising a digital processing and image analysis circuit. This determines, in use, the quality of the pickling by analyzing the appearance of the pickling front and slaves the motor drive device of the rollers 44 - 45 to adjust the rotational speed of these bodies.

When the digital processing circuit detects a C-shaped profile it automatically controls the decrease in the speed of rotation of the rollers, and when it detects a D-shaped profile, it controls the acceleration of the rotational speed of the rollers. In order to modify the general direction of the flow 36 and facilitate its evacuation after rebound of the solid particles on the surface S, the chamber 12 comprises deflectors 62, 63 and 64 fixed on the transverse edges of the lower part 35 open and inclined on the plane of the open bottom 35. The deflectors 62 to 64 and directs the flow 36 to the outlet pipe 25 while helping to oppose the release of solid particles from the enclosure 12.

The three deflectors 62, 63 and 64 provided here have an inclination with respect to the surface S which is larger for the second 63 than for the first 62 and for the third 64 than for the second 63.

For example, the deflector 62 has an inclination of 60 °, the deflector 63 an inclination of 75 ° and the deflector 64 an inclination of 85 °. Theoretically, the only deflector 62 is sufficient to straighten the flow 36 in its entirety but the path of each solid particle considered individually is subject to numerous hazards that prevent considering that each particle of the flow 36 has an exactly predictable path, this flow being all is homogeneous at the outlet of the nozzle 11 and is dissociated by the action of solid particles on the surface S. In fact, each particle detaches a small piece of coating more or less resistant and more or less heavy, and can fragment but without changing its shape, its surface always having as many tips and sharp edges, which is why some of them can be reused. In other words, the particles diminish but do not dull, so that their caliber and mass vary from one to another and, therefore, also their ballistic trajectory.

Therefore, there is a high statistical probability that particles will escape the bulk of the normally aspirated flow 36 and may remain in a small stationary vortex zone in front of the fairing 44a. The deflectors prevent the formation of this vortex, promote the elevation of solid particles and their evacuation, being reminded that the depression inside the chamber 12 promotes the entry of outside air and opposes the output of solid particles.

The action of the deflectors 62 to 64 is obviously determined as a function of the angle of attack of the solid particles and the distance that separates the nozzle outlet from the surface S. The longitudinal axis XX 'of the nozzle 11 and a tangent plane T to the active zone form an angle of attack (α) of between 35 ° and 60 °, preferably between 40 ° and 55 °, typically between 45 ° and 50 °. A value of 45 ° to 50 ° is recommended for the angle of inclination of the nozzle 11, said nozzle 11 being positioned so that its virtual axis meets the face S in the center of the lower open part 35. For obtaining an optimum result, the distance between the outlet of the nozzle 11 and the surface S must be different depending on the state of the surface S and the shoe having to adapt to different cases, it is good to be able to adjust the position of the nozzle 11 with respect to the enclosure 12.

The position and the inclination of the nozzle 11 substantially improve the quality of the pickling and, finally, it depends both on the geometry of the active elements that cooperate with each other and also on an optimum balance in the control of the flow 36, from its exit from the nozzle 11 to its evacuation via the pipe 25.

One of the advantages of the invention lies precisely in the fact that the enclosure 12 makes it possible to maintain the position and the inclination of the nozzle 11 with respect to the surface S of the airframe A, and also the position and the inclination of the discharge pipe 25, while adjusting the instantaneous action of the solid particles of a given particle size.

Thus, the pickling shoe comprises adjusting means for adjusting the angle of attack of the solid particles and / or the distance between the nozzle outlet and the surface of the object to be treated.

The area of the section A1 of the discharge pipe 25 is sufficiently greater than that of the section A2 of the nozzle 11 to allow a depression. Preferably, the area of the section of the exhaust pipe 25 is three times larger than the section of the nozzle 11. In one embodiment, a plurality of nozzles may be arranged in parallel in the shoe.

In this case, the area of the section A1 of the discharge pipe 25 is equal to three times greater than the sum of the areas of the sections A2 of the nozzles 11. For example, a shoe comprising four section area nozzles A2 has a sectional area A1 of the exhaust pipe 25 equal to twelve times A2.

In particular, the section A2 of the nozzle 11 may be of the type described in British Patent Specification No. 2,372,718 in the name of the Applicant. The The shape of the section A1 of the exhaust pipe 25 is not important. Only the difference in area must be large enough to allow depression.

The balance of the moving biphasic fluid must be maintained during all the movements that the work requires, including when the enclosure is moved laterally, which is necessary to cover a large area because the enclosure is narrow and stripping is required. performs in juxtaposed tapes as precisely as possible.

To avoid any disturbance of the flow 36, the invention provides that the interruption of stripping is not carried out by stopping the flow 36, but by diverting it in order to neutralize it without stopping it, so that the mechanical elements in question : cyclone, valves, pumps, etc. always work continuously, which is a factor not only of continuity but also of stability and ease of control. For this, according to the invention, the enclosure 12 contains a retractable flap 65 which is located near the outlet of the nozzle 11, upstream of the open central portion 35, and which is mounted to move between two extreme positions, one said "erasure" corresponding to the withdrawal of the shutter 65 and the other so-called "active" corresponding to its actuation across the flow 36 exiting the nozzle 11, in order to deflect it before the solid particles n ' reach the open central portion 35, so that the flow 36 is directed directly to the outlet pipe 25 without having any contact with the surface of the object to be treated (Figure 3).

The stripping action is thus completely neutralized without stopping the operation of the shoe.

The flap 65 has a pin 66 engaged in a slot 67 of a lever 68 pivotally mounted on an axis 69 and to which is connected a pivot 70 of a tab 71 fixed to the rod 72 of a double-acting jack 73.

A control fluid controlled by solenoid valve (not shown) drives the cylinder 73 to extract the rod 72 to turn the flap 65 into the active position (FIG. 3), or to retract it to put the flap 65 in the erased position (FIG. 2). Figures 1 to 3 and 5 show a surface S with a large radius of curvature, which could be the case of an aircraft cell whose paint is to be removed. But the same enclosure 12 must be able to adapt to different curvatures, since even a single object to be treated presents most of the time zones of different curvatures and flatnesses.

In order to be able to fit substantially tightly on surfaces S of different curvatures, the chamber 12 is articulated transversely in three segments: a central segment 12a and two end segments 12b and 12c joined by two pivots 12d. The central segment 12a of the chamber 12 is provided with a transverse rolling member 13 located in the middle portion of this segment 12a and to be in contact with the surface S. This rolling member is here constituted by a roller 13 located in the middle part, that is to say in the center of the shoe, mounted on a pivot 14 transverse to the chamber 12 and whose lower generatrix exceeds the lower contour of the central segment 12a, in order to come into contact with the surface to be treated S by maintaining said contour slightly above this surface to avoid damage by friction.

At rest, the end segments 12b and 12c are inclined with respect to the central segment 12a. The virtual axes X1, X2 and X3 indicate the relative orientation of the three segments 12a, 12b and 12c and when no pressure is applied to the shoe, the central axis X1 is vertical while the end axes X2 and X3 are divergent (see Figures 4 and 5).

The entire shoe is lowered to the surface to be treated S (FIG. 5) and the rollers 44 and 45 are applied to the surface S in a weight-dependent manner which is sufficient to ensure a sealing contact between the shoe and said shoe. S surface, sealed contact that remains during the movements of the chamber 12 since the rollers 44 and 45 roll on the surface S without discontinuity and without loss of adhesion (Figures 5 and 6). The central roller 13 is the last element that makes contact with the surface to be treated A, at its most prominent point relative to the shoe. FIG. 5 shows the case where the two segments 12b and 12c are not rigorously symmetrical since the virtual axis X2 is slightly inclined outwards, that is to say that it is divergent by relative to the central axis X1 remained vertical, while the virtual axis X3 is substantially vertical. This situation reveals that the surface S is not symmetrical with respect to its medium, located at the base of the central axis X1. Thus the shoe adapts to different curves of the objects to be treated, including different areas of the same object to be treated.

In an extreme position -not of a flat surface-, the three segments 12a, 12b and 12c are aligned by turning on the pivots 12d, their lower elements all being substantially in the same plane P (Figure 6).

In this position, the central axis X1 is vertical while the end axes X2 and X3 are convergent.

The interior of the enclosure has partitions and solid parts which determine passages which make it possible to order the flow of air around the functional elements which constitute obstacles to the displacement of the air: rollers 44, 45 and brushes 46, 47 in particular, in order to promote the movement of air towards the suction pipe 25.

It emerges from the description above that the invention makes it possible to confine the two-phase flow as close as possible to the work zone and to recover all the solid particles which have been admitted into the enclosure, so that not only does it not there is no air pollution but there is no waste or residue on the surface S, which has the considerable advantage of allowing the establishment of a coating (including paint) on the surface S, immediately after it has been stripped, thus gaining a lot of time and obtaining a high quality result since the coating is applied to the perfectly clean surface S, before it could have been soiled, oxidized, wet, etc.

The invention is not limited to the examples described and shown. For example, according to other embodiments of the invention: • the pressure means of the peripheral frame is selected from the group consisting of a set of springs, a hydraulic means, and an electromagnetic means. • The flap 65 has a curvature for guiding the flow to the suction pipe.

Claims

1. A surface-cleaning shoe capable of having a curvature by a fluid charged with solid particles, comprising at least one projection nozzle (11) extending along a longitudinal axis (X'X), an inlet capable of being connected to a fluid supply line inlet and an outlet located near a so-called active area of the surface to be treated, called pickling front, characterized in that it forms a substantially sealed enclosure (12), at the except for a face having an opening (35) adapted to be applied with respect to the surface (S) to be etched so as to respect the possible curvature of said surface, and in which the projection nozzle extends on the one hand (11) and on the other hand a suction pipe (25) connected to a vacuum generator (30), the nozzle and the suction pipe being substantially inclined in opposite directions with respect to the open face (35), respectively to project and evacuate the f a slidably loaded slid, an enclosure in which the longitudinal axis (XX ') of the nozzle (11) and a tangent plane (T) to the active zone form an angle of attack (α) of between 35 ° and 60 ° preferably between 40 ° and 55 °, typically between 45 ° and 50 °. The pickling shoe of claim 1, wherein adjusting means are provided for adjusting the leading angle of the solid particles and / or the distance between the nozzle outlet and the surface (S). 3. pickling shoe according to one of claims 1 or 2, wherein the enclosure (12) is formed of several segments (12a, 12b, 12c) articulated together by transverse pivots (12d), in order to adapt their relative inclination to conform to the curvature of the surface (S) of the object to be treated (A). 4. Stripping shoe according to claim 3, wherein a central segment (12a) of the enclosure (12) is provided with a transverse rolling member (13) located in the middle portion of this segment (12a) and disposed in contact with the surface (S) of the object to be treated (A). The pickling shoe according to any one of the preceding claims, wherein the enclosure (12) is maintained at a predetermined distance from the surface (S) of the object to be treated (A) by rolling members (44, 45) capable of being held by an operator in contact with the surface (S) so as to roll on this surface (S ) during relative movement between said enclosure (12) and said surface (S). 6. pickling shoe according to claim 5, wherein the rolling members are constituted by rotary transverse rollers (44, 45) whose surface is sufficiently flexible to permanently create between the inside of the enclosure (12) and the surface (S) an elastic contact providing a seal and movable during the relative movement between said enclosure (12) and the object to be treated (A). The pickling shoe according to any one of claims 5 or 6, wherein each transverse roller (44, 45) is associated with a cylindrical brush (46, 47) connected to a rotating drive mechanism and having elements external particles recovery assets in contact with the corresponding roller (44, 45). 8. stripping shoe according to claim 7, wherein the outer active elements are also in contact with the surface (S). A pickling shoe according to any of claims 7 or 8, wherein the drive mechanism of each rotating brush (46, 47) is unidirectional, for the purpose of brushing (46, 47) a direction constant and independent rotation of the rolling direction of the transverse roller (44, 45) corresponding. 10. stripping shoe according to claim 9, wherein the rotational direction of each brush (46, 47) is such that the portion of the brush (46, 47) closest to the surface (S) of the object to treat (A) is moved to the active area. 11. stripping shoe according to any one of claims 7 to 10, comprising two transverse rollers (44, 45) located on either side of a median plane (P) between the nozzle and the suction pipe. and two brushes (46, 47) located closer to the transverse ends of the enclosure (12) than said rollers (44, 45). The pickling shoe of any of claims 7, 9 to 11, wherein each roller (44,45) and each brush (46,47) are partially engaged in a shroud (44a, 45a; 46a, 47a). which wraps them individually except in the areas where each brush (46, 47) is in contact with the corresponding roller (44, 45). A pickling shoe according to any of claims 8 to 11, wherein each roller (44,45) and each brush (46,47) are partially engaged in a fairing (44a, 45a; 46a, 47a) which casing individually except for areas where each brush (46, 47) is in contact with the corresponding roller (44, 45) and with the surface (S). 14. stripping shoe according to any one of claims 12 or 13, wherein an auxiliary duct (48) is formed in the chamber (12) and connects on the one hand the area where a brush (46) is in contact with the corresponding roller (44) and, on the other hand, the suction line (25). 15. pickling shoe according to any one of claims 1 to 15, wherein the enclosure (12) is surrounded by a peripheral frame (50) associated with a pressure means which constantly urges it towards the surface to be treated (S) beyond the walls of the enclosure (12) and which is provided with a filter means in contact with the surface (S) of the object to be treated (A), the filter means being adapted to let the air pass without letting the particles of the flow pass. The pickling shoe of claim 16, wherein the pressing means is selected from the group consisting of a set of springs, a hydraulic means, and an electromagnetic means. The pickling shoe of claim 16, wherein the filter means is a lower peripheral brush (55) whose active elements are selected from the group consisting of bristles, synthetic foam, natural foam and a combination of those -this. A pickling shoe according to any one of claims 1 to 18, wherein the enclosure (12) contains at least one baffle (62, 63, 64) attached to the transverse edges of the open bottom (35) and inclined on the plane of the open bottom (35). 19. stripping shoe according to any one of claims 1 to 19, comprising a flap (65) mounted movably between an active position, in which it is on the normal path of the fluid (36) projected by the nozzle (11). at the exit thereof, and an erase position out of this path, means (66 to 73) being provided to move the flap (65) from its active position to its erasing position and vice versa. 20. stripping shoe according to any one of claims 1 to 20, wherein the enclosure (12) has a control window located above the open bottom portion (35) and provided with a transparent waterproof wall ( 60). 21. stripping shoe according to claim 21, characterized in that it comprises an observation apparatus (61) located opposite the window, outside thereof. The pickling shoe according to claim 21 or 22, comprising a lighting device of the active part, the lighting device being selected from the group consisting of visible wavelength illumination, lighting UV, grazing lighting and polarizing lighting. The pickling shoe according to any one of claims 5 to 23, wherein the rolling members are kinematically associated with a motor drive device. 24. stripping shoe according to any one of claims 5 to 23, wherein the rolling members are mounted free. 25. Stripping shoe according to any one of claims 22 to 24, wherein the observation apparatus is connected to a computer comprising a digital processing and image analysis circuit capable of determining the quality of the pickling stripping. analyzing the appearance of the pickling front and slaving the motor drive device of the rolling members to adjust the rotational speed of these bodies. The pickling shoe according to any one of the preceding claims, comprising one to four nozzles mounted in parallel. 27. Pickling machine comprising a pickling shoe according to any one of the preceding claims and a functional assembly (100) to which the hoses (9, 19, 27) are connected, the enclosure (12) being thus movable relative to this assembly (100), these flexible hoses being adjustable in length by drums or the like , this assembly also comprising a device (15, 16) for the ionization of air, having an output connected to a conduit (17) which leads to a channel (22) inside the enclosure (12) opening to the opposite of the suction line (25), so that the ionized air reaches the particles of the flow (36) and is sucked out in said suction line (25).