WO2006097133A1

WO2006097133A1 - Device and method for nozzle stripping by spraying a fluid loaded with solid particles forming an optimized stripping front

Info

Publication number: WO2006097133A1
Application number: PCT/EP2005/003289
Authority: WO
Inventors: Yvon Jaubertie
Original assignee: Workinter Limited
Priority date: 2005-03-14
Filing date: 2005-03-14
Publication date: 2006-09-21

Abstract

The stripping nozzles with flow of fluid loaded with solid particles can form a C- or D-shaped stripping front, causing a difference in stripping efficacy. Certain irregularities of thickness and/or hardness of the layer to be stripped can accentuate the deformation of the stripping front. The present invention aims at remedying drawbacks by coupling the nozzle to means controlling the stripping front in real time. The invention concerns a stripping device comprising a nozzle (100) coupled to at least one device for monitoring (102) the stripping front (FD) to adapt a forward moving speed increase of the nozzle (100) if the stripping front (FD) is D-shaped, and a forward moving speed decrease of the nozzle (100) if the stripping front (FD) is C-shaped, so as to make the shape of the stripping front (FD) substantially rectilinear.

Description

DEVICE AND METHOD FOR NOISE STRIPPING BY PROJECTION OF A FLUID CHARGED WITH SOLID PARTICLES FORMING A FRONT

OPTIMIZED STRIPPING.

The invention relates to a nozzle stripping device projecting a concentrated diffusion of a fluid flow loaded with solid particles, the projection forming an optimized stripping front, and a stripping process for the implementation of such a device.

There are a multitude of types of surfaces to be stripped, some of which are relatively coarse and well known rustic processes for many years are sufficient.

Other surfaces, on the contrary, require special care and for these it is no longer possible to simply project irregular materials, very hard, very aggressive, or very messy. For example, the stripping of the surface of works of art such as painted canvases, plans and drawings, manuscripts and scrolls, frescoes, sculptures in wood or minerals, painted or gilded, stained glass, porcelain, faience, goldsmith, etc. requires a rigorous control. The same goes for the facades of buildings, especially to remove deposits, patinas and marks of time, stains or graffiti.

A very different field is the industry where there are a multitude of cases that require stripping, especially for reclamation and cleaning purposes.

For example, printing cylinders that have a very finely etched surface and which have very small cells or sluices that are loaded with ink and small impurities that require scrupulous cleaning that must be both complete and leave the print surface intact.

Mention may also be made of aircraft structures, competition car bodies and, more generally, any fragile or delicate structure which is coated with one or more layers of products which must later be able to be removed, in full or layer by layer, this last condition assuming that one can remove a layer without any damage to the one immediately below the previous one.

A known projectable media is particularly suitable for pickling of delicate surfaces, namely a starchy polymer derived from wheat and which is the subject of United States Patent No. 5,066,335.

This medium is projected with standard nozzles which have the disadvantage of creating an imprecise output stream, so that by stripping a large area in successive parallel strips and juxtaposed, each band has a central area fully stripped and irregular margins which force to create the adjacent band partially overlapping the neighboring margin created previously, which prevents to guarantee a real accuracy since the lateral part of the complementary media flow can certainly cause the stripping of the missing points but also stripping additional deep points already stripped, which may result in an attack of the lower layer.

A nozzle according to the patent document GB 2 372 718 in the name of the applicant makes it possible to create a "substantially constant" energy media stream, ie without irregular margins within the meaning of the present description. This makes it possible to juxtapose the successive stripped strips in a rigorous manner, without the need to provide an overlap zone leading to a risk of irregularities and accidental attack of a layer that it is desired to preserve.

However, if the nozzle according to patent GB 2 372 718 has greatly improved the regularity and uniformity of energy over the width of the flow compared to the state of the art, it nevertheless allows to persist a difference of energy between the edges and the center of the flow, relatively small but sufficient to cause a difference in efficiency of stripping.

There may also be some unevenness in the thickness and / or hardness of the stripping layer which may lead to either insufficient stripping or excessive stripping, thus attacking the lower layer. The present invention aims to overcome these drawbacks by providing a stripping nozzle allowing a regular etching over the entire width of the particle flow and the entire height of the pickling, by coupling to means of real-time control of the pickling front in order to to obtain a substantially rectilinear front.

The approach of the invention is then to adapt the speed of progression of the nozzle to allow stripping complete and regular throughout the movement of the nozzle.

The applicant has indeed found that for certain types of pickling edges for nozzles with substantially constant energy, the appearance of this edge reflects the pickling quality as a function of the speed of progression of the nozzle. In order to determine the direction and the amplitude of the speed variation to be applied to the nozzle, the invention proposes to observe the shape of the etching front and then to adapt the advance of the nozzle as a function of this observation.

More specifically, the invention relates to a nozzle stripping device for the projection of a fluid, such as a gaseous fluid, containing solid particles and forming a pickling front having a center and edges when the nozzle advances on an object to be etched, said nozzle leaving a persisting energy difference between the edges and the center of the fluid sufficient to cause a so-called C or D pickling front shape; in this pickling device, the nozzle is coupled to at least one pickling front observation device to adapt an increase in the speed of advance of the nozzle if the shape of the pickling front is at D, and a decrease of the speed of advance of the nozzle if the shape of the pickling front is C, in order to make the shape of the stripping front substantially rectilinear.

The invention also relates to a method of pickling by spraying a fluid containing solid particles onto an object by forming a pickling front, the method comprising the steps of: a) positioning at least one preceding nozzle, above the surface of the object to be stripped; b) supplying the nozzle with fluid; c) project the fluid on the surface of the object to be stripped; d) moving the nozzle in a pickling direction to form a stripping band; e) observe the shape of the pickling front; f) adapting an increase in the speed of advance of the nozzle if the shape of the pickling front is in D, and a decrease in the speed of advance of the nozzle if the shape of the pickling front is C, in order to make the shape of the etching front substantially rectilinear; g) moving the nozzle to form another stripping band; and h) repeating steps a) to g) to form further stripping strips until the surface of the object is fully stripped.

Particular embodiments of the invention are defined in secondary claims. Other features of the invention will be set forth in the following detailed description with reference to the appended figures which represent respectively:

• Figure 1 is a schematic longitudinal sectional view of an internal nozzle structure of a pickling device according to the invention;

• Figures 2, 3 and 4, schematic cross-sectional views of the nozzle of Figure 1;

• Figure 5, a schematic longitudinal sectional view of the same nozzle, made at 90 ° to the section of Figure 1;

• Figures 6, 7 and 8, schematic cross-sectional views of the nozzle of Figure 5; • Figure 9 is a schematic longitudinal sectional view of a pickling device nozzle according to the invention, according to a particular embodiment;

FIGS. 10, 11 and 12 are diagrammatic cross-sectional views of the nozzle of FIG. 9; • Figure 13, a schematic longitudinal sectional view of the same nozzle, made at 90 ° to the section of Figure 9; • Figures 14, 15 and 16, schematic cross-sectional views of the nozzle of Figure 13;

• Figures 17, 19 and 21, schematic cross-sectional views of three shape variants of the oblong neck of the nozzle; FIGS. 18, 20 and 22 are diagrammatic cross-sectional views of three variant shapes of the outlet orifice, each corresponding to the oblong neck shape shown opposite;

FIG. 23 is a diagrammatic perspective view of a pickling device according to the invention, the observation device of which is located near the outlet of the nozzle; ^• •

• Figure 24, a schematic perspective view of a pickling device according to the invention, the observation device is coupled to the nozzle by an adjustable arm;

FIGS. 25a to 25c, stripping edge profiles showing a stripping nozzle speed that is too high (FIG. 25a) or too low (FIGS.

25b and 25c, FIG. 25c being a sectional view Y'Y according to FIG. 25b) with respect to the projection speed of the particles;

FIG. 26, a schematic view of a profile along a calibration stripping strip according to a method of the invention; • Figure 27, a schematic perspective view of a pickling device according to the invention mounted on a rolling frame; and

• Figures 28a and 28b, schematic sectional views of a pickling device nozzle according to the invention provided with a flow diversion device. Referring to Figures 1 to 8, we see a nozzle according to the invention shown in one piece, it being specified that it could also be obtained by assembling several sections, in particular to facilitate the machining of a passage 10 internal axial whose section is variable, as will be described now. The nozzle is formed of a body 1 traversed by a longitudinal tubular passage 10, one end of which constitutes an inlet 2 to be connected to a supply pipe (not shown) to drive a media to the inlet 2 according to the arrow F1, media composed of solid particles in a gaseous medium, in particular air.

At the other end of the body 1, there is an outlet 3 through which the media is projected according to the arrows F2 on a surface to strip it of one or more layers it carries.

The section of the passage 10 between the inlet 2 and the outlet 3 is variable, and the body 1 is externally formed of two segments which are a cylindrical segment 4 from the inlet 2 and a flattened spout 5 connected to the cylindrical segment 4 Internally, the passage 10 has three parts which are successively: an inlet chamber 11 with a constant circular section along the entire length of said chamber 11, an intermediate duct 12 of continuously variable section, its walls being convergent from the chamber 11 until to an elongate neck 13, thus having a minor axis and a major axis, but whose area is equal to that of the chamber 11, and finally an outlet tube 14 with an oblong section of continuously variable section, is being diverging from the neck 13 to the outlet 3, constituted by the end of the spout 5, and forming an outlet orifice 15 which has an oblong section of a shape different from that of the neck 13, the shapes of the neck 13 and l the outlet orifice 15 being both coordinated so that, while having equal areas, the media flow is projected homogeneously and accurately, without experiencing parasitic wall effects which are the cause of irregular margins.

In FIG. 3, it can be seen that the oblong section of the neck 13 has a very simple shape, since it has two parallel rectilinear edges 21 and 22 connected by fillets 23 and 24. The spacing of the rectilinear edges 21 and 22 is constant. and the media stream is uniformly flat.

As a result, the flow rate and the speed of the flow must theoretically be constant along the entire passage section 10, whereas in reality this is not the case because of the wall effects which slow down the peripheral particles with respect to the speed. particles located in the central zone, which proves to be very unfavorable for obtaining blunt-edged strips. The passage section 10 of the outlet orifice 15 is coordinated with that of the neck 13 to rectify this defect.

In FIG. 2, it can be seen that the passage section 10 of the orifice 15 has a central portion with two parallel straight edges 25 and 26 connected not by fillet but by arcs of circle 27 and 28 of greater diameter, creating two longitudinal side channels 29.

The spacing of the rectilinear edges 25 and 26 is smaller than that of edges 21 and 22, the total area of the two channels 29 being correlatively greater so that the overall passage section 10 of the outlet orifice has a larger diameter. area equal to that of the neck 13.

The equal area of the passage sections 10 of the chamber 11, the neck 13 and the outlet 15 ensures a constant flow between the inlet 2 and the outlet 3, but the different shapes that the central passage 10 presents. from the outlet of the chamber 11 to the orifice 15, give the media flow a two-phase flow at a homogeneous energy over the entire passage section 10 of the outlet orifice through a rational distribution of the forms substantially compensating for the wall effects and homogenizing the flow.

This results in improved stripping, substantially uniform over the entire width of the expelled flow, without creating irregular margins, forming strips with sharp edges that can be very precisely juxtaposed in successive passes, so that stripping is substantially constant on surfaces as large as they can be, although it is obtained by a succession of narrow bands;

The outlet jet is formed according to a flattened brush in which the energy is substantially equally distributed, whether the nozzle is operated manually or mechanically by a slave device.

Referring now to Figures 9 to 16, there is another embodiment of the nozzle according to the invention. In these figures, the same elements bear the same references as in FIGS. 1 to 8. In the chamber 11, there are two oblique divers 31 and

32 that "disturb" the random flow of entry in order to homogenize it and to concentrate it to prepare it to approach the neck with oblong section. Moreover, the solid particles of the flux are charged in static electricity by the fact of their friction against the walls of the supply pipe and against the walls of the nozzle, which is very troublesome because the particles are attracted by the surface. stripping course and part of them remain stuck, so that we must proceed to a finish consisting of cleaning the stripped surface, meticulous work, painful and long.

According to the invention, this disadvantage is remedied by providing oblique passages 33 and 34 which pass through the wall of the spout 5 and which are connected conduits (not shown) from an ionized air source. This air is compressed and injected at a high speed, or even supersonic, according to the arrows F3, in the media that flows in the nozzle 5.

A pipe (not shown) feeds the air ducts and contains a crown of known type (not shown) producing in the air electric discharges that cause its ionization so that it contains as many negative ions as positive ions.

The air circulating in this pipe is advantageously conditioned to be slightly moist.

Those ions that have the same polarity as the surface to be stripped neutralize the media particles of inverse polarity that attracted them, so that these particles do not remain stuck to the surface to be stripped. Media particles whose polarity is the same as that of the surface to be stripped can obviously not adhere to it since the identical polarities repel. The ions of opposite polarity to that of the surface to be stripped are eliminated by the earth.

It should be noted that the nozzle according to the invention equipped with ionized air injectors provides great safety of use because the introduction of this air can not cause any electric discharge and therefore does not create conditions involving a risk of inflammation of the media because there is no creation of a potential difference, so no existence of an electric current and no rise in potential surfaces to be stripped. To carry out the etching of a surface, the nozzle is displaced in translation in the direction of its longitudinal axis, at a distance and at an angle of attack that depend on the substrate to be removed and the desired result.

In FIGS. 9 to 16, it has been decided to unblock the intermediate duct 12 in a neck 40 whose oblong cross-section is elliptical.

In accordance with the explanations given above, the section of the outlet orifice must have dimensions and shape coordinated with those of the neck 40, and it can be seen in FIGS. 10 and 14 that the outlet orifice 41 has a passage section. 10 whose form could be defined as a

"Counter-ellipse", that is to say that the passage section 10 of the orifice 41 is constituted by two curved longitudinal edges 42 and 43 opposite by their convexity and connected by enlarged curves 44 and 45 which create the longitudinal side channels 29, so that the central portion of the orifice 41 is narrower than the lateral parts, being reminded that the total area of the orifice 41 is equal to that of the neck 40.

Here, the curves 44 and 45 do not continuously connect the edges 42 and 43, in a circular arc for example, but are in a broken arc and create at their intersection an edge respectively 46 and 47, which creates a precise limit to the edges the outgoing media flow through the port 3.

The conjugate shapes of the neck 40 and the outlet orifice 3 again make it possible to distribute the energy of the flow substantially uniformly, by favoring the speed of the particles in the central zone of the spout 5 and the flow rate on its two short sides. This principle can be respected while modifying the shapes of FIGS. 6 and 7 on the one hand and 14 and 15 on the other hand.

This is shown schematically in Figures 17 to 22.

The neck 13 of FIG. 17 is that which has been described with the first embodiment of FIGS. 1 to 8. With reference to FIG. 17, it can be seen that the outlet orifice 15 coordinated with the neck 13 is also described with the first embodiment of Figures 1 to 8. FIG. 19 shows an oblong neck 50 which also has rectilinear edges, as in FIG. 17, but each of them is formed by two segments 51-52 and 53-54 angularly offset to have a variable spacing from a minimum on the sides to a maximum in the central area. With reference to FIG. 19, there is seen an exit orifice of opposite shape, namely that it has two straight edges each formed by two segments 55-56 and 57-58 angularly offset at the reverse of segments 51-52 and 53-54 whose gauge varies from a maximum on the sides to a minimum in the central zone. Finally, to allow a better comparison through the approximation of the views, there is shown in Figure 21 the neck 40 of Figure 15 and in Figure 22 the outlet of Figure 14.

It can thus be seen that the neck can have different shapes, from that of FIG. 17 with straight and parallel edges, to the perfectly geometrical ellipse shape of FIG.

Since the outlet orifices have a shape coordinated with that of the corresponding neck, this shape can also be made according to different variants, it being recalled that the area of the passage section 10 of the outlet orifice must be equal to that of the neck. An internal structure as previously described allows a sufficient energy difference to persist between the edges and the center of the flow to cause a difference in pickling efficiency leading to a shape of the "C" or "D" pickling front by relation to the direction of movement. A C-profile is a profile having a generally concave or recessed shape relative to the direction of movement, that is to say that the center of the stripping band is etched after the edges. A D-profile is a profile having a generally convex or convex shape with respect to the direction of movement, that is to say that the center of the stripping band is etched before the edges

U may also exist some irregularities of thickness and / or hardness of the layer to be stripped which can lead to either stripping insufficient either to a stripping too pronounced, thus attacking the lower layer.

The simple manipulation by an operator of the previously described nozzle can also lead to uneven stripping. FIG. 23 represents a nozzle 100 whose internal structure

(Not shown in Figure 23) is consistent with those shown in Figures 1 to 22. The nozzle 100 is coupled to a digital camera 102 constituting an observation device.

The observation device 102 is located near the outlet orifice 104 of the nozzle 100.

The observation device 102 is directed towards the pickling front FD constituted by the interaction zone between the particle stream 106 and the surface S1 of the object to be stripped. This observation device makes it possible to adapt an increase in the speed of advance of the nozzle 100 if the shape of the pickling front is in D, and a reduction in the speed of advance of the nozzle if the shape of the front of the nozzle stripping is C, in order to make the shape of the stripping front substantially rectilinear.

The term observation should not be understood as restricting to optical observation in visible wavelengths. In the example, the observation device 102 is an optical digital camera. As a variant, the observation device may also be chosen from radar sensors, thermal sensors-infra-red and near infra-red, ultrasonic sensors, and the like. For example, the interest of a radar observation device is the effective detection of terrain. A thermal observation device can, meanwhile, capture the temperature of the already pickled area which is warmer - because of the impact of the fluid on the surface - that the area not yet pickled.

According to another embodiment shown in the figure

24, the nozzle 200 is coupled to an observation device 202 of the pickling front FD by an adjustable arm 206. The adjustable position of the observation device 202 is thus adaptable so that it is substantially perpendicular to the etching front regardless of the position of the nozzle 200 in use.

This setting can be automatic or manual. The observation device 202 can be advanced or retracted according to the arrow F5, and its orientation modified according to the arrow F6 thanks to the ball 208.

The outflow of the pickling nozzles has a flux whose particles are faster outside than in 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. 25a, and when the nozzle advances too slowly, the pickling front FD has a profile P2 in D such that as shown in Figure 25b. 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 25c, thus materializing the stripping of a lower layer S2 (the dimensions have been artificially increased for the sake of clarity of the figures). This is unacceptable for some applications where only a layer S1 must be stripped.

When the edges of the flux have a slightly greater energy than the center of the flux, the stripping front has a C shape similar to that shown in Figure 25a. To overcome this problem, the displacement of the nozzle must be slowed so that the center of the stripping band is exposed longer to the stream in order to be stripped. But if the pressure of the flow is too great, the edges of the flow may attack the lower layer S2 and create grooves Z as shown in Figure 25c and can discover a lower layer S3. It is therefore necessary to carry out a calibration of the nozzle to limit the appearance of grooves Z in the layer S2 when the speed of the nozzle slows down while allowing sufficiently long exposure of the center of the stripping front FD so that it becomes the most rectilinear possible, that is to say that it is substantially perpendicular to the edges of the stripping strip D.

Figure 26 illustrates a calibration method on a test surface. It includes the steps of: a) choosing a fluid pressure suitable for pickling; this choice is made within a reasonable range of values, determined according to the nature of the layer to be etched and the particles used in the fluid; b) moving the nozzle along a defined _test distance X (typically between 0.6 meters and 1.5 meters) with a constant positive acceleration to obtain a pickling gradient (see Figure 26) as a function of the moving speed along the defined distance, between an overexposure of the surface S1 allowing the flux to attack the surface S2 (X ₀ ), and an under-exposure of the surface S1 leaving on the surface S2 a surface band S1 (Xtest); c) choose the pickling speed for the most efficient pickling. Practically the most effective pickling speed is at the distance X _oPt where the surface S2 is no longer etched and where the surface S1 is entirely removed; d) adjusting the flow pressure so that a lower displacement speed (X _opt -dX / 2) does not cause overexposure, and therefore attack, of the lower layer for a given time.

For a given distance X _test and a given acceleration, the pressure P1 of the flux determines the angle a of the stripping profile Pd with respect to the horizontal H. It is therefore advisable to choose the pressure P1 so that the slope is smooth and therefore that a decrease in the speed of displacement - marked at the distance X _opt - dX / 2 - to expose the center of the pickling front FD longer does not lead to overexposure. Symmetrically, a slight increase in the speed of displacement - marked at the distance X _opt + dX / 2 - does not lead to underexposure and allows good stripping.

The pressure must also be chosen so that stripping does not take too much time. For a given distance X _test and a given pressure P2, greater than P1, it is necessary to increase the value of the acceleration to obtain a slope similar to that shown in FIG. 26, and thus good pickling conditions. A sufficient length makes it possible to see an extended gradient so that when determining the most effective stripping aspect and thus the most effective speed, a lower speed does not lead to over-exposure and does not lead to a higher speed. attack of the lower layer for a given time interval (for example 5 seconds) necessary for complete stripping of the central zone of the stripping band.

Once the calibration is performed, the stripping comprises the steps of: a) positioning at least one nozzle 100 or 200 above the surface S1 of the object to be stripped; b) supplying the nozzle 100 or 200 with fluid; c) project the fluid on the surface S1 of the object to be stripped; d) moving the nozzle 100 or 200 selo ^'n a direction of etching to form a stripping band; . e) observe the shape of the pickling front FD; f) adapting an increase in the speed of advance of the nozzle if the shape of the pickling front is in D, and a decrease in the speed of advance of the nozzle if the shape of the pickling front is C, in order to make the shape of the etching front substantially rectilinear; g) moving the nozzle to form another stripping band; and h) repeating steps a) to g) to form further stripping strips until the surface S1 of the object is fully stripped.

To improve the quality of the observation, the nozzle 200 shown in FIG. 27 comprises an illumination device 210 of the pickling front FD, the lighting device 210 both selected from the group consisting of visible wavelength illumination, UV lighting, grazing lighting and polarizing lighting.

For ease of handling, the nozzle 200 is mounted on a frame 212 provided with rolling members 214 and a handle 216 for an operator M. The observation device is connected by a functional link L1 to a computer A for displaying the image of the pickling front FD. The operator M accelerates or decelerates its thrust movement in the direction of the stripping direction according to the arrow F7 as a function of the image of the stripping front displayed by the screen B of the computer A. In this embodiment, the running gear is mounted free on the chassis.

By functional link means any means of communication enabling the observation device 202 to communicate the observation data to the computer A. According to one embodiment, the observation device is connected to means for analyzing the data. the shape of the pickling front: the computer A comprises for this purpose a digital processing and image analysis circuit able to determine the quality of the pickling by analyzing the appearance of the pickling front and to display the result of analysis. The operator therefore no longer has to determine if the shape of the pickling front is distorted because the computer directly displays whether the speed is to be increased or decreased.

To improve control of the displacement of the nozzle 200, the rollers 214 are kinematically associated with a motor drive device 218. In the embodiment shown in FIG. 27, the computer A comprises a digital processing and analysis circuit. 'picture. During the displacement, the latter determines the quality of the etching by quantitative analysis of the aspect of the pickling front FD and slaves, thanks to a functional link L2, the motor drive device 218 of the rollers 214 to adjust their speed. rotation to converge to a straight profile. A display of the analysis is therefore unnecessary in this embodiment.

Similarly, the term "functional link" means any means of communication enabling the computer A to slave the motor drive device 218. In the example, the latter comprises a wave reception module and a circuit digital processing controlling the activation of the engine.

When the digital processing circuit detects a profile in C and its amplitude of deformation, it automatically controls, according to kinematics stored in the computer and set according to the characteristics of the nozzle, the frame 212 and the drive device 218, the optimized decrease in the speed of rotation of the rollers 214 in order to stretch as fast as possible to a rectilinear profile. When it detects a profile in D, it automatically controls, according to these same kinematics, the optimized acceleration of the speed of rotation of the rollers 214 to tend towards the rectilinear profile.

The position and the inclination of the nozzle 200 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.

One of the advantages of the invention lies precisely in the fact that the frame 212 makes it possible to maintain the position and the inclination of the nozzle 11 with respect to the surface S1 of the object to be stripped. In addition, the frame 212 may comprise adjustment 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.

According to one embodiment, step g) of the etching process further comprises a step of interrupting the projection of fluid on the surface of the object to be stripped, in particular by stopping the supply of the nozzle in fluid.

In a preferred embodiment, the interruption of the projection of fluid on the surface of the object to be stripped is obtained by maintaining the supply of the nozzle fluid and an activation of a bypass device to derive the fluid so that it is redirected in the direction of the arrow F8 to the fluid supply without being projected in the direction of the arrow F9 against the surface of the object.

Thus, to avoid any disturbance of the flux 106, the invention can provide that the interruption of stripping is not carried out by stopping the flow 106, but by diverting it in order to neutralize it without stopping it, so that the elements mechanics allowing the flow to move: cyclone, valves, pumps, etc. (not shown) always work continuously, this which is a factor not only of continuity but also of stability, ease of control and regularity of stripping.

For this, a nozzle 300 according to the invention, shown in FIGS.

28a and 28b, comprises a retractable shutter 310 located near the outlet of the nozzle 300, and mounted movably between two extreme positions, one said

"Deletion" (Figure 28a) corresponding to the removal of the flap 310 and the other so-called "active" (Figure 28b) corresponding to its ^' action across the flow

106 out of the nozzle 300, to deflect it before the solid particles reach the open central portion 312, so that the flow 106 is directed directly to the outlet pipe 314 without having any contact with the surface of the nozzle. the object to be treated.

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

The flap 310 may also be constituted by a mechanical iris. In all embodiments, the flap 310 is coupled to an operator-actuable control device for moving the flap to the active position or to the erasing position.

According to other features of the invention:

• the nozzle comprises a positioning stop for holding the nozzle, in the use position, at a determined distance from the surface. This stop is useful when the nozzle is not mounted on a frame. The stop may be adjustable and / or further comprise tilting means for holding the nozzle, in the use position, at a given angle relative to a plane tangential to the surface. These inclination means can also be adjustable.

• The chassis includes several nozzles connected to the observation device.

Claims

A nozzle stripping device for projecting a fluid stream, such as a gaseous fluid, containing solid particles and having a center and two edges to form a pickling front when the nozzle is advancing on an object to be stripped said nozzle leaving a difference in energy between the edges and the center of the flow, sufficient to cause a so-called C or D stripping face, characterized in that the nozzle (100, 200) is coupled to minus an observation device (102, 202) of the pickling front (FD) for adapting an increase in the advance speed of the nozzle (100, 200) if the shape of the pickling front (FD) is in D, and a decrease in the advance speed of the nozzle (100, 200) if the shape of the pickling front (FD) is C, in order to make the shape of the pickling front (FD) substantially rectilinear.

2. pickling device according to claim 1, wherein the nozzle comprises a body through which a longitudinal tubular passage having one end constitutes an inlet to be connected to the inlet of a fluid supply pipe, and the Another end constitutes an outlet of the fluid having passed through the nozzle, the section of the tubular passage being variable between the inlet (2) and the outlet (3), said passage has an internal structure in three successive parts which are:

An inlet chamber (11) with a constant section,

An intermediate duct (12) of variable section whose walls converge from the chamber (11) to an elongated neck (13-40-

50) which has a major axis and a minor axis and whose area is equal to that of the constant section of the chamber (11),

• an outlet tube (14) oblong and variable section whose walls are diverging from the neck (13-40) to an outlet (15) of oblong section having a major axis and a minor axis.

3. pickling device according to claim 2, wherein the inlet chamber has a constant circular section.

4. Pickling device according to any one of claims 2 or 3, wherein the oblong neck (13) of the nozzle has two edges (21 and 22) rectilinear and parallel to its major axis.

5. Pickling device according to any one of claims 2 to 4, wherein the oblong neck (40-50) of the nozzle has two edges (51-52 and 53-54) whose spacing is greater in the central zone than on the sides of the collar (40-50).

6. stripping device according to claim 5, wherein each of the two edges is formed of at least two rectilinear segments (51 and 52, 53 and 54).

7. pickling device according to claim 5, wherein the two edges are curved and joined to each other by lateral connecting fillet.

8. Pickling device according to claim 7, wherein the oblong neck (40) of the nozzle has an elliptical section.

9. Pickling device according to any one of claims 2 to 8, wherein the oblong section of the outlet tube (14) of the nozzle has two edges (25 and 26) rectilinear and parallel to its major axis.

The pickling device according to any one of claims 2 to 9, wherein the oblong section of the outlet tube (14) of the nozzle has two edges whose spacing is greater in the central zone than on the sides of the tube ( 14).

The pickling device according to claim 10, wherein each of the two edges is formed of at least two straight segments.

(55 and 56, 57 and 58).

12. Pickling device according to claim 10, wherein the two edges are curved and joined to each other by lateral connecting fillet.

13. Pickling device according to any one of claims 2 to 12, wherein the oblong section of the outlet tube (14). the nozzle has two edges (55-56, 57-58) whose spacing is greater on its sides than in its central zone.

14. pickling device according to claim 12, wherein the neck (40) having an elliptical section, the oblong section of the outlet tube has two edges (42 and 43) of the same curvature as those of the ellipse but opposed by their convexity and joined to each other by lateral connection fillets (44 and 45).

15. Pickling device according to any one of claims 9, 10 or 14, wherein the oblong section of the tube (14) is enlarged laterally by two longitudinal channels (29).

16. Pickling device according to any one of claims 2 to 15, wherein the inlet chamber (11) of the nozzle contains raised elements (31 and 32) constituting flow concentrators.

17. Pickling device according to any one of claims 2 to 16, wherein the outlet tube (14) of the nozzle is determined by a sealed wall (5) which is traversed by at least one passage (33-34). intended to be connected to a source of gas containing ionized particles and opening obliquely in said tube (14), from upstream to downstream by considering the direction of movement of the fluid.

18. Pickling device according to claim 17, wherein the gas source is associated with a high speed setting device.

The pickling device of claim 18, wherein the gas moving device is adapted to print a higher speed than the sound to the gas.

20. Pickling device according to claim 17, wherein the gas contains two substantially equal fractions of ionized particles of opposite polarities.

21. Pickling device according to claim 17, wherein the gas is moist air.

22. Pickling device according to any one of the preceding claims, wherein the observation device of the front of pickling (202) is coupled to the nozzle (200) by an adjustable arm (206) so that the viewing device (202) is substantially perpendicular to the pickling front (FD) regardless of the position of the nozzle (200). ) in use.

The pickling device of any one of claims 1 to 21, wherein the viewing device (102) is located near the outlet (104) of the nozzle (100).

A pickling device as claimed in any one of the preceding claims, comprising an illumination device (210) for the pickling front (FD), the lighting device (210) being selected from the group consisting of illumination in length. visible wave, UV light, grazing light and polarizing light.

25. Pickling device according to any one of the preceding claims, characterized in that it is mounted on a frame (212) provided with rolling members (214) and a handle (216) for an operator (M ).

The pickling device of claim 25, wherein the rolling members (214) are slaved kinematically to a motor drive (218).

27. Pickling device according to claim 25, wherein the rolling members are mounted free.

28. Pickling device according to any one of the preceding claims, wherein the observation device (202) is connected to analysis means (A) of the shape of the pickling front (FD).

29. Pickling device according to claim 28, wherein the observation device (202) is connected to a computer (A) comprising a digital processing and image analysis circuit able to analyze the shape of the pickling front. (FD) and, optionally, display the result of the analysis.

30. A pickling device according to claim 29 in combination with claim 25, wherein the digital processing and analysis circuit is also adapted to slave the rolling members (214) to adjust the rotational speed thereof. bodies (214).

31. Pickling device according to any one of claims 1 to 30, wherein the observation device (102, 202) is selected from radar sensors, thermal sensors, ultrasonic sensors and optical sensors.

The pickling device of any one of claims 1 to 31, including a bypass device (310) for diverting the fluid (106) so that it is redirected to the fluid supply without being thrown against the surface (S, S1) of the object.

33. A pickling device according to any one of claims 1 to 32, comprising a positioning stop for holding the nozzle, in the use position, at a determined distance from the surface.

34. A pickling process according to ^'Claim 33, wherein the stop is adjustable.

35. Pickling device according to any one of claims 33 or 34, wherein the stop comprises tilting means for holding the nozzle, in the use position, at a given angle relative to a plane tangential to the surface. .

36. Pickling device according to claim 35, wherein the tilting means are adjustable.

37. A method of stripping by projection on an object of a fluid containing solid particles, the projection forming a pickling front, characterized in that it comprises the steps of: i) positioning at least one nozzle (100, 200 , 300) according to any one of claims 1 to 36, above the surface (S, S1) of the object to be stripped; j) supplying the nozzle (100, 200, 300) with fluid (106); k) projecting the fluid on the surface (S, S1) of the object to be stripped;

I) moving the nozzle (100, 200, 300) in a pickling direction (F7) to form a stripping band; m) observe and analyze the shape of the pickling front (FD); n) adapting an increase in the advance speed of the nozzle (100, 200, 300) if the shape of the pickling front (FD) is in D, and a decrease in the speed of advance of the nozzle (100, 200, 300) if the shape of the pickling front (FD) is C, to make the shape of the pickling front (FD) substantially rectilinear; o) moving the nozzle (100, 200, 300) to form another stripping band; and p) repeating steps a) to g) to form further stripping strips until the surface (S, S1) of the object is fully stripped.

38. Pickling method according to claim 37, wherein step g) further comprises a step of interrupting the projection of fluid (106) on the surface (S, S1) of the object to be stripped.

39. Pickling method according to claim 38, wherein the interruption of the projection of fluid (106) on the surface (S, S1) of the object to be stripped is obtained by stopping the feeding of the nozzle. (300) in fluid (S, S1).

40. A pickling method according to claim 38, wherein the nozzle (s) (300) is / are according to claim 31, and wherein the interruption of the fluid projection (106) on the surface (S, S1) of the object to be stripped is obtained by maintaining the fluid supply (300) of the nozzle (300) and activating the bypass device (310) to divert the fluid (106) so that it is redirected to (F8) the fluid supply without being projected (F9) against the surface (S, S1) of the object.