Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
  • B29C70/38—Automated lay-up, e.g. using robots, laying filaments according to predetermined patterns
  • B29C70/386—Automated tape laying [ATL]
  • B29C70/388—Tape placement heads, e.g. component parts, details or accessories

Definitions

• the present invention relates to a method of inspecting fibers draped by means of a fiber placement machine, to check the drape quality and / or to perform calibration operations of said fiber placement machine, in particular operations. calibration of cutting systems and rerouting systems of the placement head of such a machine.
• the fibers conventionally used are continuous flat fibers, also called wicks, generally unidirectional, and comprising a multitude of filaments.
• the deposited fibers may be dry fibers or fibers pre-impregnated with thermosetting or thermoplastic resin.
• the fibers typically have widths of 1/8, 1/4 or 1/2 inches.
• the term "fibers” also refers to fibers of greater width, greater than 1/2 inch, conventionally referred to as a strip in placement technology.
• the parts are manufactured automatically by fiber placement machines which conventionally comprise a placement head moving system, said head having a compaction roll for contacting the mold for applying the fibers, and a guiding system for guiding the application fiber (s) onto said roll.
• fiber placement machines which conventionally comprise a placement head moving system, said head having a compaction roll for contacting the mold for applying the fibers, and a guiding system for guiding the application fiber (s) onto said roll.
• the guide system makes it possible to bring the fibers substantially edge to edge on the roll in the form of a strip.
• the head further comprises cutting systems for cutting the fibers, and re-routing systems to reroute each fiber that has just been cut to the roll, so that at any time it can stop and resume the application of a band, as well as choose the width of the band. Locking systems may further be provided to block each fiber that has just been cut.
• Each cutting system conventionally comprises for each fiber a blade operated by a pneumatic actuator type actuator cooperating with a counterblade or against a tool.
• Each rerouting system conventionally comprises for each fiber a counter-roller operated by a pneumatic jack type actuator for pressing the fiber against a roller or driving roller positively rotated.
• cutting systems and rerouting systems need to be calibrated to take into account in particular the reaction times of the actuators, as well as the length of fiber between the cutting blade and the zone or line of contact between the roller and the surface of the draping, this length of fiber being called cutting length or re-routing length.
• the minimum cutting and re-routing accuracies sought for fiber placement in the aeronautical sector are generally of the order ⁇ 2.5mm.
• one or more strips are draped on the flat layup surface of a plate between two reference lines, and for each fiber, the gaps at the beginning of the fiber and at the end of the fiber are visually identified and manually measured at the foot. slider. When these deviations are out of tolerance, compensation is applied to parameterize the actuators concerned. This calibration operation is long and tedious.
• the proféllo materials comprises a transmitter capable of emitting a linear laser beam on the draping surface, and a receiver or camera which simultaneously retrieves an image of the projected beam, an analysis system then makes it possible to analyze the projected beam , which represents the profile of the surface at the analyzed area, and to deduce the position of the fiber end.
• the Profilometer is used to perform fiber start position measurements and end positions of fibers, these measured positions are then compared to theoretical positions and a Error message is sent to the operator when the deviations are outside a tolerance range.
• This profilometer measurement process reduces the measurement time and avoids measurement errors.
• This method requires a very accurate Cartesian-type displacement system, perfectly calibrated, so that the measured position, which is deduced from the programmed position of the profilometer, can be compared to a programmed theoretical position.
• the fold and / or the piece is inspected to check the quality of draping, including the positioning of the fold by controlling the contour of the fold, it is that is, by controlling the position of the cutting edges of the fibers, at the beginning and at the end of the path, and / or the position of the longitudinal edges of the outer fibers of the folds.
• This inspection of the folds can be done manually or automatically by automatic inspection systems, as described above, based on the use of precise displacement system.
• the object of the present invention is to provide a fiber inspection solution to overcome the aforementioned drawbacks, which is applicable to any type of fiber placement machines.
• the present invention provides a method of inspecting fibers draped by means of a fiber placement machine, said machine comprising a fiber placement head and a displacement system adapted to perform relative movements of the head. relative to a drape surface for performing draping operations, characterized in that it comprises
• the position of a fiber edge is detected with a detection system mounted on the machine, preferably on the fiber placement head, and is compared to the position of a reference mark corresponding to the desired theoretical position of the fiber edge or representative of the latter, this position of the reference mark being detected with the same detection system.
• the reference mark can be any reference mark.
• a mark present on the draping surface of a draping tool for example a groove engraved on the draping surface or a different colored line present on the draping surface;
• the fiber edge inspection can be performed to check the draping quality, for example the outline of a workpiece or a fold of a workpiece, including a patch of a workpiece.
• Inspection of the fiber edges can also be performed to calibrate the fiber placement machine, in particular for calibrating the cutting systems and the fiber re-routing systems, by inspecting the cutting edges of the fibers, also called edges of fibers. end of the fibers, and designating the fiber start edges and the fiber end edges.
• the method according to the invention proposes a solution for inspecting fibers, and in particular for calibrating a fiber placement machine, which is effective, whatever the displacement system used, in particular poly-articulated robot-type displacement systems. , whose accuracy may be less good, than that of a Cartesian displacement system conventionally used in machine tools, but whose repeatability of the precision error is very good.
• the draped fibers may be continuous flat fibers, of the wick type, in particular carbon fibers, consisting of a multitude of carbon threads or filaments.
• the fibers may be so-called dry fibers, provided with a binder, or fibers pre-impregnated with a thermosetting or thermoplastic polymer or resin.
• step b) comprises comparing the reference position and the actual position to determine if the actual position of the fiber edge is within a tolerance range, step c) comprising generating an alert information if the actual position is outside the tolerance range.
• the warning information may be in various forms, for example in the form of a report, and / or an audible signal and / or a light signal, and / or a light mark projected on the fiber edge whose position is not in conformity, and / or information communicated to a control system to automatically perform correction operations, especially in the case of a calibration of the head.
• the detection of the reference position comprises the detection of the position of a reference line present on the drape surface, for example a line engraved on the application surface of a tool.
• the detection of the reference position comprises the detection of the position of a projected reference line on the drape surface and / or the previously draped fibers, preferably a line projected by a laser projector.
• the reference position and the real position are detected by means of a camera, with an image analysis to compare the two positions and possibly measure the distance between the two positions.
• the reference position and the real position are detected by means of a profilometer, with an image analysis of the projected linear laser beam recovered by the profilometer camera to compare the two positions and possibly measure the distance between the two positions.
• step a) comprises, successively, - the detection of the reference position
• the detection of the real position of an edge of the draped fiber makes it possible in particular to use reference marks present on the draping surface that can be covered after draping.
• step a) comprises, successively,
• the method comprises
• the draping of at least one fold the detection of the position of at least one reference line, preferably in a closed loop, the detection of the actual positions of the beginning edges of the fibers and of the end edges of the fibers and possibly longitudinal edges of outer fibers of the fold,
• the method comprises
• the method comprises, for the calibration of each re-routing system of the fiber placement head,
• the method comprises draping a fiber between two reference lines in a path perpendicular to the two reference lines.
• the comparison step comprises measuring the difference between the reference position and the actual position said method further comprising automatically correcting the control of the cutting system and / or the rerouting system as a function of this measured deviation, and preferably a reiteration of steps a) to c).
• the calibration method according to the invention is used to calibrate each cutting system and each re-routing system associated with each fiber.
• the placement head comprises fiber locking systems
• the calibration of cutting systems and / or rerouting systems generally comprises corrections of the control of said locking systems.
• the method comprises
• FIG. 1 is a partial schematic side view of a placement head equipped with a profilometer for the implementation of a placement head calibration method according to the invention, said head being in the process of detecting reference positions on a calibration plate;
• FIG. 2 is a schematic view from above of the calibration plate
• FIGS. 3 and 4 are enlarged views of the details A ( and A 2 of FIG. 2) illustrating the step of detecting the reference positions;
• FIG. 5 is a schematic view of the image recovered by the profilometer camera from which a reference position will be defined;
• FIG. 6 is a top view of the calibration plate after draping a test strip with the fiber placement head
• FIGS. 7 and 8 are enlarged views of the details A 3 and A 4 of FIG. 6 illustrating the step of detecting the positions of the fiber start edges and the end edges of the fibers;
• FIGS. 9 and 10 are diagrammatic views of two images retrieved by the profilometer camera from which the positions of two fiber end edges of the strip will be defined;
• FIG. 11 is a top view of the calibration plate according to an alternative embodiment, with draping of a second fiber strip made after calibration of the head;
• FIG. 12 is a diagrammatic view from above of a draping tool illustrating a method of inspection of fold contours according to the invention.
• FIG. 13 is a partial schematic enlarged view from above of the draping tool of FIG. 12 illustrating a method of inspection of fold contours according to an alternative embodiment of the invention.
• Figures 1 to 11 illustrate a calibration method of the placement head according to the invention using a profilometer and a calibration plate.
• the fiber placement machine allows automatic draping in contact with strips formed of one or more fibers.
• the fiber placement head 2 known per se, comprises a compacting roller 21 for applying the fibers to contact on a drape surface.
• the fibers enter the head in the form of two plies of fibers, and the head comprises a guide system 22 for guiding the fibers to the compaction roller in the form of a fiber web in which the fibers are arranged sideways. side by side, for example substantially edge to edge.
• the head comprises, on either side of the guiding system, cutting systems 23 for individually cutting each fiber passing in the guiding system, locking systems 24 arranged upstream of the cutting systems with respect to the direction. fiber advance, to block each fiber just cut, and rerouting or drive systems 25, arranged upstream of the cutting systems, to individually drive each fiber, this in order to be able to stop and resume at any time applying a fiber, as well as choosing the width of the strip.
• the draping of a strip is achieved by relative movement of the head relative to the substantially planar draping surface of a draping tool.
• the head comprises for example a support structure (not shown) on which is mounted the guide system and by which the head can be assembled to a displacement system, able to move the head in at least two directions perpendicular to each other. 'other.
• the displacement system comprises for example a robot comprising a wrist or poly-articulated arm at the end of which is mounted said head.
• the head is fixed and the mold is adapted to be moved relative to the head to perform the draping operations.
• the head is for example designed to receive eight fibers, and allow the application of strips of 8 fibers 6.35 mm (1/4 inch) wide, for example carbon fibers, consisting of a multitude of son or carbon filaments, the head comprising for each fiber a cutting system, a locking system and a re-routing system.
• the head is equipped with a heating system (not shown) for heating during draping the fibers to be draped and / or the surface of the drape or fibers previously draped, just upstream of the roller relative to the direction of advance of the head, to at least soften the resin or binder, and thus promote the adhesion of the strips together and / or to the draping surface.
• the heating system is, for example, of the infrared type for draping fibers pre-impregnated with a thermosetting resin, or of the laser type for dry fibers provided with a thermoplastic binder or binder, or for fibers pre-impregnated with a thermoplastic resin. .
• the head is further equipped here with a profilometer for performing calibration of the head by inspecting the fibers of a band previously draped on the draping surface the plane of a plate 1 called calibration.
• the profilometer represented schematically under the reference 26, comprises, in a manner known per se, a laser emitter capable of emitting a linear laser beam on an analysis zone of the draping surface, and a receiver or camera which retrieves images of the beam projected on the area of analysis. An analysis system then makes it possible to analyze these images in order to deduce the positions of fiber edges.
• the calibration plate 1 has a rectangular closed-loop engraved reference line or groove 10 formed of four engraved reference lines 11, 12, 13, 14 arranged parallel to the edges of the plate and forming a rectangle. Calibration of the head is performed by draping a strip of fibers between two opposed etched reference lines, for example a first line 11 and a second line 12.
• the first line corresponds to the desired theoretical positions of the fiber start edges, namely the programmed positions
• the second line corresponds to the programmed positions of the end edges of fiber.
• a first step the head is moved along a first trajectory 31 above the first reference line 11, in order to recover by means of the profilometer images at different positions of the head along this trajectory, and to obtain several positions. reference of fiber start edges, each associated with a position of the head along the path.
• Figure 5 schematically illustrates the projected beam recovered by the profilometer camera, on which the engraved line clearly stands out.
• head is moved along a second path 32 above the second reference line 12 in order to retrieve images at different positions of the head along this path, and obtain several reference positions of end edges of fibers, each associated at a position of the head.
• test strip 40 is then draped over the calibration plate, from the first reference line 11 to the second reference line 12, by moving the head along a path 33, as illustrated in FIG. 6.
• Each of the fibers is conveyed at the beginning of the trajectory to the compaction roller via its associated rerouting system, and is cut at the end of its trajectory by its associated cutting system.
• the head is then moved again according to the first trajectory 31 above to retrieve images at different positions of the head along this trajectory, said positions of the head corresponding to those used to recover the reference positions of the fiber start edges. , these images for detecting the actual positions of the fiber start edges.
• the head is then moved along the second trajectory 32 to retrieve images at different positions of the head along this trajectory, said positions of the head corresponding to those used to recover the reference positions of the end edges of the fiber, these images to detect the actual positions of the end edges of fiber.
• the actual position of each fiber start edge is compared to a reference position obtained for the same position of the head.
• the difference between the actual position and the reference position is measured, and corresponding correction information is created to correct the control of the rerouting system associated with said fiber.
• the actual position of each end edge of fiber is compared to a reference position obtained at the same position of the head.
• the difference between the actual position and the reference position is measured, and corresponding correction information is created to correct the control of the cutting system associated with said fiber.
• FIG. 9 illustrates the image of the projected beam recovered by the camera for a first position of the head, on which appears the leading edge of the first fiber 41 of the test strip.
• This image is compared to the image of the projected beam recovered by the camera for the same position of the head on which the reference position appears.
• the comparison of the two images makes it possible to recover the difference e 1 between the real position and the reference position.
• the fiber has been rerouted too early, the measured gap is used to correct the rerouting system in order to reroute the first fiber later.
• FIG. 10 illustrates the image of the projected beam recovered by the camera for a second position of the head, on which appears the start edge of the second fiber 42 of the test strip.
• This image also shows the reference position of the reference line.
• the difference e 2 of the actual position relative to the reference position can be deduced from this image, without requiring comparison with an image of the reference position recovered before draping.
• the fiber has been rerouted too late, the measured gap is used to make a correction to the rerouting system to reroute the second fiber earlier.
• FIG. 11 illustrates a calibration plate according to an alternative embodiment, comprising on either side of the reference line 10, so-called tolerance lines 81, 82, also etched, each forming a rectangle. These tolerance lines allow an operator to visually check whether the positions of the fiber start edges and the finished end edges of fibers are within the tolerance range. If not, the operator can restart a calibration operation.
• the method is described with a single reference position and a single actual position detected by fiber.
• several reference measurements and several real positions are measured and compared.
• a description of a ply contour inspection method of a part according to the invention will now be made with reference to FIG. 12.
• the part is obtained by superimposing several plies in defined orientations, each pleat being made by draping one or more strips in one orientation.
• a fold contour inspection is performed after draping each fold.
• a first fold 5 is draped, for example at 0 °, on the draping surface 101a of a tool 10, formed here of a plate.
• a laser projector is used to project on the draping surface a pattern or reference line 110 corresponding to the desired contour of the fold, i.e. at the reference positions of the fiber edges.
• the projector here projects a reference line 110 formed of four rectilinear reference lines arranged in a rectangle, of which a first line 111 and a second line 112 respectively corresponding to the reference positions of the end edges of the fiber and to the reference positions of the edges of the fiber. beginning of fiber of the different fiber bands draped side by side, and a third line 113 and a fourth line 114 respectively corresponding to the reference positions of the outer longitudinal edge of the outer fiber of the first draped strip 51 and the outer longitudinal edge of the outer fiber of the last strip 52 draped.
• the laser projector is for example fixed on the ground.
• the laser projector can be mounted to move on said linear axis.
• the robot is for example mounted on a carriage slidably mounted on the linear axis, and the laser projector is fixedly mounted on said carriage.
• the head equipped with a camera, is moved over the drape surface, along paths corresponding to the projected reference lines 111-114, to recover images of the projected lines and edges of fibers.
• An image analysis makes it possible to compare the position of the fiber edges with respect to the position of the reference lines. Alert information is issued when the difference between the actual position of a fiber edge and a reference position is above a maximum value.
• the strip or strips containing non-compliant fiber edge positions may then be removed to be re-draped.
• a second fold 6, here consisting of a 45 ° fiber patch is then used to drape a second fold 6, here consisting of a 45 ° fiber patch. After draping this fold at 45 °, a reference line 120 formed of four straight lines and corresponding to the position of the desired contour, is projected, and the head is moved above the tool to recover images containing the edges of fibers and projected lines, to deduce as previously described possible deviations.
• the projector is used to project two reference lines, each in a rectangular closed loop, corresponding to the upper and lower limits for the fiber edge positions.
• a first projected reference line 130 is disposed at a tolerance distance + ⁇ of a virtual reference line, shown schematically at 7, corresponds to the programmed theoretical reference positions.
• a second projected reference line 140 is arranged at a tolerance distance - ⁇ of the virtual line 7.
• the criterion applied is that, for each fiber, any end edge of detected fiber is arranged between the two reference lines 130, 140.
• the criterion applied is that at least the outermost corner of each fiber, namely the upper corner 161a of each fiber 61 in FIG. 13, is disposed between the two reference lines 130, 140.

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• Engineering & Computer Science (AREA)
• Robotics (AREA)
• Chemical & Material Sciences (AREA)
• Composite Materials (AREA)
• Mechanical Engineering (AREA)
• Moulding By Coating Moulds (AREA)
• Treatment Of Fiber Materials (AREA)

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• 2015
  • 2015-03-06 FR FR1500444A patent/FR3033280B1/fr active Active
• 2016
  • 2016-03-02 WO PCT/FR2016/000031 patent/WO2016142589A1/fr unknown
  • 2016-03-02 EP EP16713509.4A patent/EP3265297A1/de not_active Withdrawn

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