Method for treating sealing membrane suitable for tank and corresponding device

Abstract

The invention relates to a method for treating a sealing membrane (2) for a tank for containing a liquid gas, using a treatment tool (72) mounted on a movable device (70), the treatment method comprising: a step of generating a profile of a portion of the sealing membrane (2) on a predetermined path of the movable device (70) on the sealing membrane (2); a step of dividing the predetermined path into treatment regions between which at least one change is required to be made to the configuration of the movable device (70) and / or of the treatment tool (72); a step of treating the sealing film (2); -at least one sub-step of changing the configuration of the movable device (70) and / or of the treatment tool (72) between two of the treatment areas during the treatment step.

Description

Technical Field

[0001] The present invention relates to the field of tanks for liquid gases, such as liquefied natural gas (LNG), in particular for marine or river transport or for shore containers. More specifically, the present invention relates to a method for treating sealing films suitable for such tanks. Background Art

[0002] Each of these transport tanks has a capacity of several thousand cubic meters of liquid gas, or even tens of thousands of cubic meters of liquid gas. Ships that transport liquefied gas have cargo holds specially equipped to accommodate these tanks, and their cargo holds are usually divided into several tanks. Such tanks can also be built outside the ship for land-based storage of liquid gas. The gas remains liquid at atmospheric pressure, for example at -163°C (degrees Celsius) for LNG. Therefore, it must be watertight and thermally insulated. As a result, the inner surface of such a tank is covered with a sealing membrane, which is usually made of an assembly of metal sealing plates (usually stainless steel) welded together, each sealing plate being part of the sealing membrane of the tank.

[0003] In order to weld these metal sheets together, using a welding machine, the operator has to follow the edges of these sealing plates, which are arranged two by two in part next to each other (riveted joint), using a guide. The operator runs the program on the machine, and the machine, equipped with a welding torch, welds the edges of the sealing plates as they pass over them, while all the time adjusting the distance between the welding torch and the parts to be welded using a positioning sensor mounted on the machine.

[0004] This operation is then followed by the stripping of the weld bead, since the welding operation has produced metal oxides on the edges of the sealed plates, which may eventually damage the integrity of the membrane (corrosion). The stripping operation uses a machine equipped with a position sensor and a laser stripping head that gradually strips the weld bead produced by the welding machine using the same guide rails. The position sensor allows positioning the laser stripping head as the machine moves along the rails.

[0005] These welding and stripping operations are very time-consuming. Since the convex parts of the sealing film must be taken into account, the machine moves gently along the edge of the sealing plate to be welded or stripped. The correct positioning of the welding torch or laser stripping head takes time and slows down the welding or stripping operation.

[0006] Therefore, there is a need to improve the execution time of welding and / or peeling operations on sealing films of tanks for conveying liquid gases. Summary of the invention

[0007] The present invention at least partially remedies the drawbacks of the prior art by providing a method for treating a sealing film suitable for a tank intended to contain a liquid gas, the method allowing to facilitate the treatment performed on the sealing film of the tank for the liquid gas. To this end, the present invention proposes a method for treating a sealing film suitable for a tank intended to contain a liquid gas, the method using a treatment device for treating the sealing film, the treatment device comprising a movable device and at least one treatment tool mounted on the movable device, the treatment method comprising the step of treating the sealing film by the treatment tool along a predetermined path of the movable device, the treatment method comprising:

[0008] A preliminary generation step of generating a profile of at least a portion of the sealing film on a predetermined path using a movable support equipped with a position sensor and passing the position sensor over the sealing film, during which the following sub-steps are repeated:

[0009] determining a distance between a reference point of the position sensor and at least one point of the sealing membrane portion,

[0010] Record the distance determined,

[0011] moving the movable support,

[0012] The contour of the sealing film portion is generated according to the distance recorded during the recording sub-step,

[0013] The processing method is characterized in that it further comprises:

[0014] a step of dividing the predetermined path into processing areas of the sealing film according to the profile generated during the generating step, requiring at least one modification of the configuration of the movable device and / or the processing tool between the processing areas, and

[0015] During the processing step, at least one sub-step of modifying the configuration of the movable device and / or the processing tool between two of the processing areas.

[0016] In particular, if the position sensor is an optical sensor, the sub-step of determining the distance comprises the following sub-steps:

[0017] sending an initial optical signal to a point on the surface of the sealing film,

[0018] receiving a return optical signal corresponding to the initial optical signal, and

[0019] A distance between a reference point of the position sensor and a point on the surface of the sealing film is determined based on the initial optical signal and the return optical signal.

[0020] The generated contour is, for example, a two-dimensional contour of the sealing film portion in a plane orthogonal to a main extension plane of the sealing film portion.

[0021] The predetermined path may be derived from an analysis step of analyzing the contour generated in a previous contour generation step.

[0022] Thanks to the invention, the contour of the sealing film portion is produced and can be used for a subsequent processing step of the sealing film portion, the execution of which will be accelerated by the a priori knowledge of the contour of the film. By means of the invention, the subsequent processing step does not use position sensors to determine the distance between the processing tool and the sealing film and the positioning of the processing tool relative to the film, although the processing step can use other sensors, for example to confirm the position of the processing tool along a predetermined path.

[0023] In one embodiment of the present invention, the sealing film includes a first sealing plate and a second sealing plate arranged against each other, the sealing film portion is the edge of the first sealing plate, a portion of the edge of the second sealing plate is arranged below the edge of the first sealing plate, and the position sensor is passed through a point that is also suitable for determining the distance between the edge of the second sealing plate and the reference point of the position sensor, and the generation step generates the contour of the edge of the first sealing plate and the contour of the edge of the second sealing plate. The edge of the second sealing plate means the peripheral area of ​​the second sealing plate. More specifically, the edge of one sealing plate is arranged on a portion of the other sealing plate (hereinafter, although not necessarily at the periphery of the plate, the portion may also be referred to as the edge of the plate).

[0024] In this embodiment of the invention, the movable support is mounted on a track fixed to the sealing membrane, for example along the edges of the first and second sealing plates. When the sealing membrane comprises corrugations to assist in the deformation of the can, these corrugations form a grid on the sealing membrane, the track is fixed, for example, to at least two nodes of the grid, and the distance between the edges of the sealing plates of the sealing membrane and the track is substantially constant, i.e. constant within + / - 3 mm.

[0025] According to an advantageous feature of the invention, the position sensor is a scanning laser sensor, the sub-step of determining the distance corresponds to the sub-step of determining several distances for one and the same position of the movable support, and the generating step produces a three-dimensional profile of the sealing film portion. In the case where the sealing film portion comprises two sealing plate edges resting against each other, the three-dimensional profile therefore comprises the profile of each sealing plate edge of the sealing film portion.

[0026] The movable device is preferably also a movable support and therefore comprises both the position sensor and the processing tool, although the position sensor is not used during the processing step.The processing device may comprise tracks on which the movable device travels and / or a remote server.

[0027] According to an advantageous feature of the processing method according to the invention, the processing step comprises at least one sub-step of modifying the configuration of the movable device and / or the processing tool, and the processing step is preceded by a step of dividing the predetermined path into processing areas of the sealing film according to the profile generated during the generation step, between which processing areas said at least one sub-step of modifying the configuration of the movable device and / or the processing tool is necessary. Thus, a priori knowledge of the profile of the sealing film portion allows sequential processing of the treatments, each processing sequence corresponding to a processing area for which no modification of the configuration of the movable device and / or the processing tool is required, such a configuration modification sub-step being implemented only between each processing sequence.

[0028] The processing zones are preferably ordered by the processing device in a processing sequence that allows minimizing the processing time of the processing device on the sealing film. The sequence may correspond to a discontinuous treatment of the sealing film during the first pass of the movable device over the sealing film, where several passes through the predetermined path are required to process the entire sealing film.

[0029] In one embodiment of the treatment method according to the invention, the treatment corresponds to an operation of stripping the weld bead at the level of two sealing plate edges of the sealing film, the sealing film portion being the edge of a first sealing plate against which the edge of a second sealing plate is placed.

[0030] In one embodiment of the processing method according to the invention, the configuration modification sub-step generates a displacement of the movable device and / or the processing tool, during which the processing is interrupted. In other words, the configuration modification sub-step corresponds to an "empty" movement of the movable device and / or the processing tool, i.e. without any processing.

[0031] In an embodiment of the processing method according to the invention, the sealing film comprises corrugations which form a grid on the sealing film, and the processing tool is a laser stripping head positioned on a predetermined path for stripping the weld bead, the configuration modification sub-step is triggered to position the impact point of the laser beam projected by the laser stripping head on the area located at the foot of the corrugations of the sealing film. Thus, the configuration modification sub-step allows the processing tool to be positioned so that it can fully process the processing area, in which case the laser stripping head is positioned so that the impact point of the laser beam can scan the entire area located at the foot of the corrugations of the sealing film.

[0032] The processing areas are, for example, configured to allow ablation on each of the processing areas using only laser scanning without requiring any additional movement of the movable device or the laser ablation head.

[0033] In another embodiment of the processing method according to the invention, the processing step comprises at least one sub-step of modifying the configuration of the movable device and / or the processing tool, and the processing step comprises a sub-step of reading the profile generated during the generating step, determining the triggering of said at least one sub-step of modifying the configuration of the movable device and / or the processing tool. In this other embodiment of the invention, the profile reading sub-step is performed completely before the processing step, or when the processing step is implemented. The reading of the profile determines the moment when it is necessary to modify the configuration of the movable device and / or the processing tool when implementing the processing step.

[0034] In this further embodiment of the treatment method according to the invention, the treatment corresponds for example to a welding operation at the level of two sealing plate edges of the sealing membrane, the sealing membrane portion being the edge of a first sealing plate against which the edge of a second sealing plate is arranged.

[0035] For example, in this further embodiment of the processing method according to the invention, the sealing film comprises corrugations which form a grid on the sealing film, and the processing tool is a welding tool, the modification sub-step corresponds to a change in the speed of the movable device when the movable device reaches the corrugations of the sealing film. In this example, the reading sub-step can thus allow the detection of the foot of the corrugations of the sealing film portion to be welded, which allows the speed of the movable device to be adjusted.

[0036] The treatment step is optionally followed by a further step of generating a profile of the sealing film portion that has just been treated, which allows implementing a method for controlling a sealing film comprising the following steps:

[0037] generating a contour of at least a portion of the sealing film using the method for generating a contour according to the invention,

[0038] A comparison is made between the distance obtained using the previously generated contour and the corresponding distance of a pre-registered template of the sealing film portion.

[0039] The absolute value difference between these distances is compared, for example, with a predetermined threshold, and if the difference is greater than the predetermined threshold, an abnormality is detected.

[0040] The invention uses, for example, a device for generating a profile of at least a portion of a sealing film suitable for a tank configured to contain a liquid gas, the generating device comprising a movable support provided with a position sensor, the generating device also comprising:

[0041] determining means for determining the distance between a reference point on the position sensor and at least one point on the sealing membrane portion,

[0042] recording means for recording said distance determined by said determining means,

[0043] moving means for moving the movable support along a predetermined path above the sealing membrane,

[0044] and generating means for generating a profile of the sealing film portion based on the distance recorded by the recording means along the predetermined path.

[0045] The generating means may comprise tracks on which the movable support travels and / or a remote server. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Other characteristics and advantages of the invention will emerge more clearly on reading the following description on the one hand and on reference to a number of exemplary embodiments given in an indicative and non-limiting manner on the other hand in the attached schematic drawings, in which:

[0047] [ Figure 1 ] shows, in one embodiment of the invention, means for generating a profile of at least a portion of the sealing film during a step in which the position sensor passes over the sealing film,

[0048] [ Figure 2 ] represents a step of generating a profile of at least a portion of a sealing film according to the invention in one embodiment of the invention,

[0049] [ Figure 3 ] represents a device for welding a sealing film in an embodiment of the present invention, which implements the step of welding a sealing plate to an adjacent sealing plate,

[0050] [ Figure 4 ] shows the steps in a method for welding a sealing membrane according to the present invention in one embodiment of the present invention,

[0051] [ Figure 5 ] represents a device for peeling off a sealing film in one embodiment of the present invention, which implements the step of peeling off the sealing film,

[0052] [ Figure 6 ] shows Figure 5 The impact area of ​​the laser beam of the peeling device is shown.

[0053] [ Figure 7 ] shows a stripping head for the laser beam, including a reflective module,

[0054] [ Figure 8 ] shows the steps in a method for peeling off a sealing film according to the present invention in one embodiment of the present invention,

[0055] [ Fig. 9 ] indicates that Figure 8 The peeling method includes peeling the corrugated portion of the sealing film during the peeling step, and

[0056] [ Fig.10 ] show the steps in a method for controlling a sealing membrane in one embodiment of the present invention. DETAILED DESCRIPTION

[0057] according to Figure 1 The embodiment of the invention shown uses a contour generating device 1 to generate a contour of a portion of a sealing film 2 suitable for a tank configured to contain a liquid gas. In this embodiment of the invention, the sealing film 2 is made of 1.2 mm thick metal plates that are welded together or to be welded together.

[0058] The tank is usually defined by the inner hull of a transport vessel and has a capacity of several thousand cubic meters of liquid gas, or even tens of thousands of cubic meters of liquid gas. The sealing film 2 covers the entire inner surface of the tank of such a transport vessel. In order to compensate for the deformation of the tank due to temperature changes or navigation conditions, the sealing film 2 includes ribs or corrugations 24 that intersect the surface of the sealing film 2. Viewed in profile in a plane parallel to the longitudinal direction L and the transverse direction T orthogonal to the longitudinal direction L, the sealing film thus includes a flat area 22 and a corrugation 24.

[0059] The profile generating device 1 comprises a movable support 11 equipped with a position sensor 12 which measures the distance separating a reference point on the device from the impact point on the membrane. The position sensor 12 is a class 2 laser distance sensor with a measuring frequency of 300 to 600 Hz (Hertz). Alternatively, the position sensor 12 may be a LVDT (Linear Variable Differential Transformer) type sensor.

[0060] In this embodiment of the invention, the movable support 11 is mounted on a track 3 positioned about ten centimeters above the surface of the sealing membrane 2, opposite the edge of the sealing plate 2-1 of the sealing membrane 2. In this embodiment of the invention, the contour of the edge of the sealing plate 2-1 of the sealing membrane 2 is generated.

[0061] The track 3 follows this edge of the sealing plate 2-1 arranged in the longitudinal direction L, the distance between the edge of the sealing plate 2-1 and the track 3 being constant within a few centimeters, the track being able to be several tens of meters long, for example thirty meters, and possibly made in several pieces. The track 3 is held by a clamp 4, for example attached to the nodes of the grid formed by the corrugated portion of the sealing membrane 2.

[0062] The step 200 of generating the contour of the edge of the sealing plate 2-1 is implemented by the generating device 1 through software and / or hardware, and Figure 2 Shown in.

[0063] The step 200 of generating the profile is preceded by the step 100 of passing the position sensor 12 over the edge of the sealing plate 2 - 1 .

[0064] Passing the position sensor 100 comprises a first sub-step 102 of determining the distance d between a reference point of the position sensor 12 and a point on the surface of the sealing plate 2-1. The point on the surface of the sealing plate 2-1 is perpendicular to the position sensor 12. In this embodiment of the invention, the position sensor 12 measures in a vertical direction V relative to the position sensor 12, the vertical direction V being orthogonal to the longitudinal direction L and the transverse direction T. In this determination sub-step 102, the generating device 1 reads the measurement value returned by the position sensor 12. The generating device 1 comprises a software module that interfaces with the input and output of the position sensor 12. In this embodiment of the invention, the sub-step 102 itself therefore comprises sub-steps implemented by the position sensor 12, which are:

[0065] An initial optical signal is sent 1022 to a point on the surface of the edge of the sealing plate 2-1. The initial optical signal is, for example, a laser pulse.

[0066] receiving 1024 a return optical signal corresponding to the initial optical signal, the return optical signal being, for example, a reflection of a laser pulse initially sent to the surface of the sealing plate 2-1, and

[0067] The distance d between a reference point of the position sensor 12 and a point on the surface of the edge of the sealing plate 2-1 is measured 1026 from the initial and return optical signals; the measurement typically uses the time between sending a laser pulse and receiving a reflected laser pulse.

[0068] Alternatively, other types of sensors may be used, such as infrared optical sensors or capacitive sensors.

[0069] A subsequent sub-step 104 of step 100 of passing the position sensor 12 is to record the distance d determined in sub-step 102 in a memory of the generating device 1 .

[0070] Finally, the last sub-step 106 of the step 100 through which the position sensor 12 passes is the displacement of the movable support 11. The generation means 1 comprise a software module interfacing with the actuator of the movable support 11. The combination of the speed of movement of the movable support 11 and the pulse frequency of the laser beam results in a movement step length, for example a tenth of a millimeter, and in this embodiment of the invention the speed of movement of the movable support 11 is between 100 and 200 mm / s (millimeters per second).

[0071] Sub-steps 102 to 106 of step 100 of passing the position sensor 12 are repeated until the movable support 11 reaches the end of the track 3 or any stop instruction or command.

[0072] When the end of the track is reached, which is detected by the generating means 1, for example by the detection of a stop on the track 3, or by the detection of reaching a predetermined distance travelled on the track 3, programmed in the generating means 1, the generating means 1 implement a step 200 of generating the profile of the edge of the sealing plate 2-1 according to the distance recorded during the recording sub-step 104. The generating step 200 is performed in a software module of the generating means 1, which may comprise a remote server.

[0073] In this embodiment of the invention, during this generation step 200, the generation means 1 generate the profile of the edge of the sealing plate 2-1 in the form of a point in a reference system situated in a plane orthogonal to the main extension plane of the sealing membrane 2, that is, in a plane parallel to the vertical direction V and the longitudinal direction L. The profile generated is therefore a profile having at least two dimensions, one of which corresponds to the position reached by the movable support 11 on the rail 3 since the start of step 100, and the other dimension corresponds to the distance d determined by the generation means 1 during sub-step 102 when the movable support 11 is in this position reached on the rail 3.

[0074] According to the use of the generated profile, the generating means 1 filters the distances d recorded during sub-step 104 and the generated profile then comprises only certain points corresponding, for example, to the distances d recorded at the borders of the flat areas 22 and at the tops of the corrugations 24 of the sealing membrane 2 .

[0075] In an alternative embodiment of the invention, the position sensor 12 is a scanning laser sensor which, for the same position of the position sensor 12 on the rail 3, measures the distances between a reference point of the position sensor 12 and various points on the surface of the sealing membrane 2 located on a section parallel to the transverse direction T, these distances being measured in a vertical plane passing through the position sensor 12, parallel to the transverse direction T and the vertical direction V. In this variant embodiment, the generating means 1 determine in each sub-step 102 for the same position of the movable support 11 a distance vector which is recorded in a sub-step 104. In this variant embodiment, the profile generated in step 200 is therefore a three-dimensional profile of the edge of the sealing plate 2-1.

[0076] The edge of the sealing plate 2-1 is arranged on the edge of another sealing plate 2-2 (at Figure 6 In the case of welding to the other edge, for example, the three-dimensional contour generated in this other embodiment variant is, for example, the contour of the edge of the first sealing plate 2-1 and the edge of the second sealing plate 2-2.

[0077] In another embodiment of the invention, the movable support 11 is not arranged on the track 3 and travels along at least a portion of the sealing membrane 2, moving directly on the surface of the sealing membrane 2, moving along a predetermined or adaptive path, depending on the obstacles encountered by the movable support 11 on its path.

[0078] An example of a method for processing a sealing film 2 using the step 200 of generating a profile according to the invention is now described. Figure 3 In the example of use shown, the processing method is a method for welding the edge of the sealing plate 2 - 1 to the edge of the sealing plate 2 - 2 , which is implemented by the welding device 7 in hardware and / or software.

[0079] The welding device 7 comprises a track 3 following the edge of the sealing plate 2-1 and a movable device 70 on which a welding torch 72 is mounted. The welding device 7 may also include a remote server. Alternatively, the welding device 7 comprises a movable device consisting of a movable support 11 of the generating device 1, in which case the movable support 11 is equipped with a welding torch in addition to the position sensor 12 and, optionally, with a laser stripping head 52 for a subsequent stripping operation (e.g. Figure 5 as shown).

[0080] Depend on Figure 4 The welding method implemented by the welding device 7 shown in FIG. 1 comprises first steps 100 and 200 of passing the position sensor 12 and generating the profile of the edge of the sealing plate 2-1, thereby implementing the previously described Figure 1 and Figure 2 Describes the steps for generating contours.

[0081] The next step 600 of the welding method is a step of firmly welding the edges of the sealing plates 2-1, 2-2 using the welding torch 72. During this welding step, the sealing plates 2-1 and 2-2 are welded by melting the material from the edge of the sealing plate 2-1 to the edge of the sealing plate 2-2, and this melting is performed as the movable device 70 advances along the track 3.

[0082] The first sub-step 602 is to read the profile of the edge of the sealing plate 2-1 generated during the step 200 of generating the profile. The profile generated here is a two-dimensional profile in a plane parallel to the longitudinal direction L and the vertical direction V, and includes a division of the predetermined path into areas to be welded, which are flat areas 22 or corrugated areas 24, which allows positioning of the corrugated areas 24 and flat areas 22. The profile includes, for example, giving, for each position of the movable device 70 on the track 3, the value of such a parameter, the value of which indicates the nature of the area vertically above the welding torch 72, for example, a value of 0 is associated with a flat area 22, and a value of 1 is associated with a corrugated portion 24.

[0083] The reading sub-step 602 is performed continuously while the movable device 70 travels along the track 3, or before the movable device 70 travels along the track 3. In fact, the reading sub-step 602 allows detecting the positions of the movable device 70 for which the speed of the movable device 70 must be modified during the welding of the sealing plates 2-1 and 2-2 of the sealing membrane 2. Thus, these positions can be predetermined so as to distinguish between the flat areas 22 and the corrugated portions 24.

[0084] In this embodiment of the welding method according to the invention, as the mobile device 70 advances along the track 3, a reading substep 602 is performed. As long as the properties of the vertical area of ​​the welding torch 72 detected during this reading substep 602 do not change, the speed of the mobile device 70 remains constant. When the properties of the vertical area of ​​the welding torch 72 detected during this reading substep 602 change, the reading substep 602 triggers a substep 604 for changing the speed of the mobile device 70. In particular, during this substep 604:

[0085] - when the reading sub-step 602 has detected the foot of the transition from the flat area 22 to the corrugated portion 24, the speed of the movable device 70 is reduced and the orientation of the welding torch is modified by adapting the parameters;

[0086] When the reading sub-step 602 has detected the transition from the foot of the corrugations 24 to the flat area 22 , the speed of the movable device 70 is increased again and the orientation of the welding torch is modified by adapting the parameters.

[0087] Based on the three-dimensional profile generated as described above, during the reading sub-step 602, any deviation in the position of the film can be detected and lateral corrections can be made for the correct positioning of the welding torch.

[0088] Another example of a method for processing a sealing film 2 using the step 200 of generating a profile is now described. Figure 5 In the other example of use shown, the processing method is a method for stripping the weld bead 26 between the edge of the first sealing plate 2 - 1 and the edge of the second sealing plate 2 - 2 , which is implemented by the stripping device 5 through hardware and / or software.

[0089] The stripping device 5 comprises a track 3 following the edge of the sealing plate 2-1.

[0090] and a movable device consisting of the movable support 11 of the generating device 1, comprising both the position sensor 12 and the laser stripping head 52. The stripping device 5 may also comprise a remote server.

[0091] Advantageously, the stripping device 5 may also include a suction nozzle (not shown) to allow oxide dust or smoke generated during stripping of the sealing film 2 to be sucked up. It should be understood that the stripping device 5 implements pickling via a laser beam projected onto the area to be pickled.

[0092] The laser stripping head 52 can be tilted on the movable support 11 so that it projects the laser beam 6 at an angle of incidence 27 of the order of a few degrees relative to the normal 25 of the surface of the sealing film 2. This allows to prevent the reflection of the laser beam 6 projected by the laser stripping head 52 from damaging it due to the return of the incident beam. In practice, the laser stripping head 52 projects a class 4 laser beam 6 (according to standard 1EC60825-1) with a power preferably between 20 W and 200 W, a pulsed emission frequency preferably between 100 kHz and 200 kHz and produces a beam with a wavelength of 1064 nm. These characteristics of the laser beam 6 allow the impurity layer or oxide layer 28 formed on the weld bead 26 to be stripped.

[0093] The movable support 11 comprises an electric motor 53 capable of rotating a rotation axis 51 fixed to a laser stripping head 52. In this way, the laser stripping head 52 can be rotationally moved relative to the movable support 11, which allows the incident angle 27 of the laser beam 6 to be modified relative to the normal 25 of the surface of the sealing film 2. Therefore, the stripping device 5 comprises means for modifying the inclination of the laser stripping head 52 relative to the normal 25 of the surface of the sealing film 2.

[0094] The stripping device 5 also comprises means, not shown, for varying the height h of the rotation axis 51 on the movable support 11 and thus the height in the vertical direction V of the laser stripping head 52 .

[0095] These means for modifying the inclination and the height of the head 52 are means for modifying the configuration of the laser stripping head 52 on the movable support 11 . Alternatively, the stripping device 5 comprises means for modifying the height of the movable support 11 relative to the rail 3 .

[0096] The stripping device 5 also comprises means for moving the movable support 11 on the rails 3 , the same means as for moving the device 1 for generating a profile, namely software interfacing with at least one actuator of the movable support 11 .

[0097] The laser stripping head 52 comprises at least one focusing lens 54, the focal length of which is between 80 mm and 360 mm, thereby allowing the laser beam 6 to be focused on an impact area 61 on the surface of the sealing film 2. The laser beam 6 is scanned across the impact area 61, and each pulse generates Figure 6The impact points 63 are shown, and the impact points 63 overlap to ensure that the weld bead 26 is completely stripped. The impact area 61 is approximately two centimeters wide (in the transverse direction T), which means that a weld bead 26 of approximately one centimeter width can be completely stripped.

[0098] pass Figure 7 The structure of the laser stripping head 52 shown enables this scanning. The stripping device 5 includes a laser beam generator 56, which projects a laser beam 6 onto a reflective module 57 at the free end of the laser stripping head 52. For ease of explanation, the laser stripping head 52 is Figure 7 . The laser beam generator 56 is actually outside the laser stripping head 52, and it is the optical fiber 9 that brings the generated beam into the laser stripping head 52. The reflection module 57 is, for example, an assembly of mirrors that deflects the trajectory of the laser beam 6 leaving the beam generator in a direction D1 included in a plane parallel to the longitudinal direction L and the vertical direction V, or in a direction D2 included in a plane parallel to the transverse direction T and the vertical direction V. Alternatively, the reflection module is located outside the laser stripping head 52 on the movable support 11. Therefore, the stripping device 5 comprises means for modifying the orientation of the laser beam 6 independently of the orientation of the laser stripping head 52.

[0099] The method for stripping the weld bead 26 implemented by the stripping device 5 comprises a first step 100 and a step 200 for passing the position sensor 12 and for generating a profile of the edge of the sealing plate 2-1, such as Figure 8 As shown in , and implementing the previous Figure 1 and Figure 2 Describes the method used to generate contours.

[0100] The next step 400 is to divide the predetermined path of the stripping device 5 along the track 3 (corresponding to the path along the portion to be treated of the sealing film 2) into processing areas of the sealing film 2, in this case the areas to be stripped, according to the profile generated in step 200, for which it is necessary to reconstruct the laser stripping head 52 or the movable support 11 before stripping the area to be stripped in question.

[0101] In order to increase the stripping speed of the edges of the sealing plates 2-1, 2-2, in units of mm / s, it is preferred to limit the movement of the movable support 11 and the laser stripping head 52 as much as possible. To this end, the stripping method sequentially strips the areas to be stripped that have been cut during step 400, which are configured to allow stripping on each of these areas to be performed using only laser scanning implemented by the reflection module 57, without any additional movement of the movable support 11 or the laser stripping head 52. To achieve this, the size of the area to be stripped is predefined to keep the incident angle 27 small enough to allow effective stripping of the area to be stripped. In particular, this incident angle allows the focal length of the focusing lens 54 to be maintained within an acceptable tolerance range. For example, for a focusing lens 54 with a focal length of 330 mm (millimeters), the tolerance margin is 3 mm.

[0102] Therefore, in step 400, each of the flat areas 22 is divided into two halves, and each of the corrugated portions 24 is divided into six areas to be peeled off, such as Fig. 9 More specifically, when the movable support 11 moves in the direction 55 of the longitudinal direction L, it first peels off the slope 241 of the corrugated portion 24. In order to effectively peel off this slope 241, the laser beam leaving the reflection module 57 has an incident angle 27 of almost zero on the surface of the corrugated portion 24. To this end, the laser peeling head 52 uses a rotation axis 51 that allows the laser beam 6 to have an angle of 70° or 50° counterclockwise relative to the vertical direction at the output of the laser peeling head 52.

[0103] Thus, the first area 243 to be peeled off at the foot of the ramp 241 is defined to be attacked by the laser beam 6 at an angle of 70° relative to the vertical direction V, which allows the radius of curvature of the foot of the corrugation 24 to be matched to within a few degrees.

[0104] The second area 245 to be peeled off in the middle of the slope 241 is also defined to be attacked by the laser beam 6 at an angle of 50° relative to the vertical direction V, which allows matching the normal of the surface of the corrugation within a few degrees on the central area of ​​the slope 241.

[0105] Finally, a third zone 247 to be peeled off is defined at the top of the ramp 241 so that it can be attacked by the laser beam 6 at an angle of 50° relative to the vertical direction V, which allows matching the radius of curvature of the top of the corrugation 24 within a few degrees.

[0106] Similarly, when the movable support 11 moves in the other direction 59 of the longitudinal direction L, it peels off the other slope 242 of the corrugated portion 24 in a similar manner to the peeling off of the slope 241 of the corrugated portion 24. In particular, it starts to peel off the fourth area 244 at the foot of the slope 242, the laser beam 6 has an angle of 70° clockwise relative to the vertical direction V, then peels off the fifth area 246 in the middle part of the slope 242, the laser beam 6 has an angle of 50° clockwise relative to the vertical direction V, and finally peels off the sixth area 248 at the top of the slope 242, the laser beam 6 has an angle of 50° clockwise relative to the vertical direction V.

[0107] The regions 243 , 245 , 247 , 244 , 246 , 248 to be stripped partially overlap one another at at least one of their lateral edges, so that stripping is performed uninterruptedly over the entire weld bead 26 along a predetermined path.

[0108] At the end of step 400, the stripping device 5 stores data in a ROM (read-only memory) or RAM (random access memory) memory, the predetermined path being divided into areas to be stripped, each area to be stripped being associated with a single configuration of the movable support 11 and / or the laser stripping head 52. During the stripping of the areas to be stripped in step 400, the movable support 11 and the laser stripping head 52 remain stationary. The areas to be stripped are also sorted in a list by the stripping device 5 according to a processing order that allows minimizing the time taken to strip the sealing film 2 by the stripping device 5. As will be seen later, this sorting does not correspond to a continuous stripping along the predetermined path.

[0109] It should be noted that, alternatively, the segmentation step 400 is at least partially performed in parallel with the contour generation step 200 .

[0110] The next step is a processing step of the sealing film 2 by a processing device, in this case a stripping step 500 implemented by a stripping device 5 along a predetermined path. This processing step comprises at least one sub-step of modifying the configuration of the movable device and / or the processing tool of the processing device, in this case a sub-step 502 of modifying the configuration of the movable support 11 and / or the laser stripping head 52. In particular, the sub-step 502 corresponds to modifying the height of the laser stripping head 52, and / or the position of the movable support 11 on the track, and / or the angle of the laser stripping head 52 relative to an axis orthogonal to the main extension plane of the sealing film 2.

[0111] Contrary to the prior art, the peeling step 500 does not use a position sensor relative to the sealing film 2 .

[0112] More specifically, at the beginning of the stripping step 500, the stripping device 5 places the movable support 11 longitudinally on the rail 3 and orients the laser stripping head 52 to be able to strip the first area to be stripped in the list of areas to be stripped resulting from the dividing step 400, without any further movement of the movable support 11 and the laser stripping head 52. This modification of the configuration of the movable support 11 and / or the laser stripping head 52 corresponds to a first configuration modification sub-step 502 on the current area to be stripped, which at the beginning of the step 500 is the first area to be stripped.

[0113] The second sub-step 504 of the peeling step 500 is the peeling of the current peeling area, which is scanned by the laser beam 6 in the current peeling area. As an indication, the peeling speed in this embodiment is 7 cm 2 / s (square centimeters per second).

[0114] Finally, the third sub-step 506 of the stripping step 500 is to change the current area to be stripped if the list of areas to be stripped has not been completely covered, otherwise the stripping step 500 is terminated. If the list of areas to be stripped has not been completely browsed, the current area to be stripped is replaced with the area to be stripped immediately after the current area to be stripped in the list of areas to be stripped, and the next sub-step of the stripping step 500 is a new configuration modification sub-step 502 considering the new area to be stripped.

[0115] Sub-steps 502 to 506 are thus repeated until the weld bead 26 is completely stripped.

[0116] In this example of use of the present invention, the configuration modification sub-step 502 corresponds to:

[0117] - longitudinal displacement of the movable support 11, and / or

[0118] - a change in the orientation of the laser lift-off head 52, and / or

[0119] - The height of the laser lift-off head 52 relative to the sealing film 2 is changed.

[0120] These configuration modification sub-steps are performed without projecting the laser beam 6, ie "null". This reduces the ablation time compared to the prior art.

[0121] In other examples of use of the present invention, this configuration modification sub-step 502 may include other types of movement, such as lateral movement of the movable device and / or the processing tool.

[0122] Thus, the stripping method is carried out sequentially, wherein between each stripping sequence on the area to be stripped a configuration modification step 502 is performed in between. Successive stripping sequences do not necessarily correspond to adjacent areas of the sealing film 2.

[0123] For example, during step 100, the movable support 11 makes a continuous pass along a predetermined path on the track 3 at the edge of the sealing plate 2-1 in the direction 55 of the longitudinal direction L. This continuous pass is performed empty. The dividing step 400 is then performed by the stationary generating device 1 of the stripping device 5. In step 500, the stripping device 5 then performs a first run in the direction 59, during which the stripping device 5 strips all the inclined surfaces 242 of the corrugated portion 24 it encounters, as well as the first half 221 of the flat area 22 it encounters (in Figure 5 ). The stripping device 5 then performs a second run in direction 55, during which the stripping device 5 strips all the inclined surfaces 241 of the corrugated portion 24 it encounters, as well as the second half 222 of the flat area 22 it encounters.

[0124] The stripping device 5 first performs a first run, during which it strips the slope 241 of the corrugation 24, said slope 241 being an ascending slope in the direction 59 of this first run, and then performs a second run, during which it strips the slope 242 of the corrugation 24, said slope 242 being an ascending slope in the direction 55 of this second run, which allows to increase the speed of execution of the stripping method, in particular the rotation time of the laser stripping head 52. In fact, if the stripping device 5 strips each corrugation 24 in a single unidirectional run along the track 3, the laser stripping head 52 will have to perform several 140° rotations, which is not the case in this example of the stripping method according to the invention. The stripping method according to this example is optimized in terms of the longitudinal movement and rotation of the laser stripping head 52 for equally dividing the predetermined path into the areas to be divided.

[0125] Of course, other variations of the embodiment of the stripping method according to the present invention are possible, in particular, as an alternative, the corrugated portion 24 of the sealing film 2 is only divided into four to-be-stripped areas, and then each of the inclined surfaces 241, 242 is divided into two to-be-stripped areas, one covering the foot of the inclined surfaces 241, 242, and the other covering the top of the inclined surfaces 241, 242. In this case, the to-be-stripped areas corresponding to the foot of the corrugated portion are stripped at a laser beam angle of 70° relative to the vertical direction V, and the to-be-stripped areas corresponding to the top of the corrugation are stripped at a laser beam angle of 50° relative to the vertical direction V.

[0126] Now about Fig.10 A method for controlling a sealing membrane 2 is described. The control method comprises a first step 100 of passing a position sensor 12 and a step 200 of generating a profile of at least a portion of the sealing membrane 2, which implements the previous description of Figure 1 and Figure 2 Describes the method used to generate contours.

[0127] The next step 700 of the control method is the comparison between the distances obtained using the contours generated in the generation step 200 and the corresponding distances of the pre-registered template of the sealing film portion 2. These distances correspond, for example, to:

[0128] - distances measured on the sealing film 2 and corresponding distances obtained from the pre-registered template,

[0129] - or the distance measured in the vertical direction V between a point on the reference axis (eg the track 3 ) and the sealing membrane, and the corresponding distance from a pre-registered template.

[0130] The comparison calculates the difference between the distance obtained using the generated contour and the corresponding distance of the pre-registered template. The difference calculated in step 700 is then compared with a predetermined threshold. The predetermined threshold is, for example, one or two millimeters and is used to detect incorrect positioning of the corrugated portion 24 on the sealing film 2, or deformation of the corrugated portion 24 on the sealing film 2.

[0131] In the next step 800, if the absolute value of the distance calculated in step 700 is less than a predetermined threshold, steps 700 and 800 are repeated on other distances of the contour generated in step 200 and the pre-recorded template until the generated contour has been fully run or an anomaly is detected in step 800.

[0132] On the other hand, if the absolute value of the distance calculated in step 700 is greater than a predetermined threshold, an abnormality in the sealing membrane 2 is detected, which triggers, for example, in step 800 the step of recording the abnormality and / or sending an alarm to a user interface.

[0133] Of course, the invention is not limited to the examples described above and many modifications may be made to these examples without departing from the scope of the invention.

Claims

1. A method for processing a sealing film (2), the sealing film (2) being suitable for a tank for containing liquid gas, using a processing device (5, 7) for processing the sealing film (2), the processing device (5, 7) comprising a movable device (70, 11) and at least one processing tool (72, 52) mounted on the movable device (70, 11), the processing method comprising a step (600, 500) of processing the sealing film (2) by the processing tool (72, 52) along a predetermined path of the movable device (70, 11), the processing method comprising: A preliminary generation step (200) of generating a profile of at least a portion of the sealing film (2) on the predetermined path using a movable support (11) equipped with a position sensor (12) and passing the position sensor over the sealing film (2) (100), during which the following sub-steps are repeated: determining (102) a distance (d) between a reference point of the position sensor and at least one point of the sealing membrane portion (2), Record the distance (d) determined by (104), moving (106) the movable support (11), generating (200) a profile of the sealing film portion (2) based on the distance (d) recorded during the recording sub-step (104), The processing method is characterized in that it further comprises: a step (400) of dividing the predetermined path into processing areas (243, 244, 245, 246, 247, 248) of the sealing film (2) according to the profile generated during the generating step (200), between which at least one modification (502) of the configuration of the movable device (11) and / or the processing tool (52) is required, and During the processing step, at least one sub-step (502) of modifying the configuration of the movable device (11) and / or the processing tool (52) between two of the processing areas.

2. The processing method according to claim 1, wherein: The sealing film (2) comprises a first sealing plate and a second sealing plate arranged against each other, the sealing film portion (2) being an edge of the first sealing plate (2-1), the edge of the first sealing plate (2-1) being arranged on a portion of an edge of the second sealing plate (2-2), and wherein passing the position sensor (12) through (100) is also suitable for determining a distance (d) between a point of the edge of the second sealing plate (2-2) and a reference point of the position sensor, the generating step (200) generating a profile of the edge of the first sealing plate (2-1) and the edge of the second sealing plate (2-2).

3. The processing method according to claim 1 or 2, wherein: The position sensor (12) is a scanning laser sensor, the sub-step of determining (102) the distance (d) corresponds to the sub-step of determining (102) a plurality of distances (d) for the same position of the movable support (11), and the generating step (200) produces a three-dimensional profile of the sealing membrane portion (2).

4. The processing method according to any one of claims 1 to 3, wherein: Each processing area (243, 244, 245, 246, 247, 248) corresponds to a processing sequence of processing steps (600, 500), during which the configuration of the movable device (11) and / or the configuration of the processing tool (52) does not need to be modified (502).

5. The processing method according to any one of claims 1 to 4, wherein: The dividing step (400) is followed by sorting the processing areas (243, 244, 245, 246, 247, 248) according to a processing order.

6. The processing method according to claim 5, wherein: The treatment sequence corresponds to a discontinuous treatment of the sealing film (2).

7. The processing method according to any one of claims 1 to 6, wherein: The configuration modification sub-step (502) generates a displacement of the movable device (11) and / or the processing tool (52), the processing being interrupted during the configuration modification sub-step (502).

8. The processing method according to any one of claims 1 to 7, wherein: The treatment corresponds to an operation of stripping the weld bead (26) at the level of two sealing plate edges (2-1, 2-2) of the sealing film (2), the sealing film portion (2) being the edge of a first sealing plate (2-1) against which the edge of a second sealing plate (2-2) is arranged.

9. The processing method according to any one of claims 1 to 8, wherein: The sealing film (2) comprises corrugated portions (24) which form a grid on the sealing film (2), and wherein the processing tool (52) is a laser stripping head positioned on the predetermined path for stripping the weld bead (26), and the configuration modification sub-step (502) is triggered to position the impact point (63) of the laser beam (6) projected by the laser stripping head on the area (243, 244) located at the foot of the corrugated portion (24) of the sealing film (2).

10. The processing method according to claim 9, wherein: The processing areas are configured to allow stripping using only laser scanning on each of the processing areas (243, 244, 245, 246, 247, 248) without any additional movement of the movable device (11) or the laser stripping head.

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