Automatic composite material strip deposition head

Abstract

An automatic deposition head for composite material strips onto a mold surface, and the head comprising: - a placement device; - a feeding mechanism; - a cutting mechanism; and in that the placement device further comprises a compaction mechanism, said compaction mechanism being characterized in that it comprises at least 3 compaction rollers, of which: - a fixed central roller integral with the placement device, - at least 2 peripheral rollers arranged rearward and laterally relative to the central roller, each peripheral roller being self-adjusting radially along a plane coplanar to an XY plane in response to a change in the inclination of the mold deposition surface on which compaction is performed for that peripheral roller. Fig. 1

Description

Title of the invention: Automatic deposition head for composite material strips. TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to the field of composite material deposition and lamination techniques suitable for manufacturing composite structures. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Until recently, large composite structures were generally created using manual lamination techniques involving the manual placement of mats or plies of reinforcing fibrous material in large molds. Several layers of fibrous material are arranged in the mold. The fibrous material is usually in the form of strips containing glass or carbon fibers. Once the strips are arranged in the mold, resin is introduced using a technique such as resin transfer molding (RTM) or vacuum-assisted resin transfer molding (VARTM). Alternatively, the mats can be pre-impregnated with resin, i.e., prepreg, which eliminates the need to supply resin to the mold. In all cases, the layup is generally subjected to a consolidation and curing process under vacuum and temperature control.

[0003] The presence of profile differences, particularly curved ones, on molds during deposition forces any deposition machine to make many additional passes and adapt the position of the deposition head, severely limiting production productivity.

[0004] The use of composite fiber placement or deposition allows the production of so-called double-curvature parts, that is, parts whose Gaussian curvature is non-zero, unlike ruled surfaces such as cylinders or cones. It should be noted, however, that tape draping also allows the manufacture of complex parts. However, if the variations in Gaussian curvature become too significant, it is impossible to produce the draped part while maintaining a certain level of quality.

[0005] Current deposition heads also have a significant mass, imposing significant mechanical stresses on their movement and orientation mechanism, promoting wear of this mechanism, as well as high energy consumption.

[0006] Five-axis machines comprising an automatic composite material deposition head are known, which can adjust their inclination and position in the space in such a way as to allow the deposition of composite material on a deposition surface via a compaction mechanism having a straight roller.

[0007] Such machines have the disadvantage of requiring a number of head movements in position and orientation, as well as a very large number of head passes when it comes to covering large parts or parts with evolving curved profiles.

[0008] By evolving curved profiles, we mean a part having a non-zero Gaussian curvature that varies over the surface of said part.

[0009] Such machines have the disadvantage of not allowing the roller equipping these deposition heads to have satisfactory contact on the deposition surface since the said roller is limited to a compaction force along an orientation normal to the center of the roller with respect to the deposition surface, which poses problems when the profile of the deposition surface is curved by introducing a difference in contact between the center of the roller and its ends.

[0010] The present invention remedies these drawbacks. Summary of the invention

[0011] The invention relates to an automatic deposition head for strips of composite material onto a mold surface, and the head comprises: -a placement device for placing a strip of composite material onto the surface of the mold; -a feeding mechanism to bring the strip along a path extending from a composite material feed to the placement device; -a cutting mechanism capable of cutting the strip of composite material to a chosen length.

[0012] According to a general definition of the invention, the placement device for the deposition head further comprises a compaction mechanism, said compaction mechanism being characterized in that it comprises at least three compaction rollers, of which:

[0013] - a fixed central roller integral with the placement device, said central roller having an axis of revolution X perpendicular to an axis Y representing the orientation of the placement device with respect to a mold deposition surface; and

[0014] -at least two peripheral rollers arranged rearward in a direction of progression of the deposition head at the level of the deposition surface of the mold 100 and laterally with respect to the central roller, each peripheral roller being self-adjusting radially along a plane coplanar to an XY plane in response to a change in the inclination of the mold's depositing surface on which compaction is implemented for this peripheral roller.

[0015] Advantageously, the deposition head according to the invention allows real-time adaptation of the material strip deposition to surface variations of the part mold, while allowing increased adaptability of the deposition on surfaces with significant curvature, thus minimizing the number of passes of the head required over the surface to obtain the target part.

[0016] In practice, the compaction rollers are arranged in a V-shaped formation, in which the central roller is located in front of the peripheral rollers in a direction of progression of the deposition head at the level of the deposition surface of the mold.

[0017] In addition, each peripheral roller is pivotally mounted on the placement device via a fixed proximal end attached to the placement device, and having a distal end movable radially along the plane coplanar to an XY plane on which translation means are mounted, said translation means comprising a fixed end and an end attached to the distal end of each peripheral roller, said translation means being configured to radially adjust each peripheral roller along the plane coplanar to an XY plane and maintain a chosen applied force when said peripheral rollers are radially self-adjusting.

[0018] Such a structure allows increased adaptability of the deposit on surfaces with significant curvature, but also when the deposit surface includes asymmetrical curvature / inclination variations with respect to the deposit path of the head according to the invention.

[0019] In practice, the translation means have pneumatic control following at least one setpoint value of compaction pressure chosen maintained continuously over the entire length of the strip, said pneumatic control being configured to be self-regulating if a measured pressure value exceeds a given threshold range.

[0020] Advantageously, the pneumatic control of the translation means of each peripheral roller is individually self-regulated.

[0021] For example, the means of translation are of the pneumatic type.

[0022] According to an embodiment according to the invention, the distance separating the proximal end of each peripheral roller is less than the length of the central roller.

[0023] Such a configuration makes it possible to limit the accumulation of air pockets during compaction by allowing the lateral evacuation of air potentially trapped between the deposition surface and the material strip.

[0024] In practice, the cutting mechanism is of the straight cut type.

[0025] By way of non-limiting example, the strip of material to be deposited comprises a width of between 300mm and 500mm.

[0026] According to a particular embodiment of the invention, the strip of material to be deposited comprises a width of 400mm.

[0027] Advantageously, the deposition head according to the invention allows for deposition whose compaction parameters are controlled so as to be reactively adapted to the actual curvature of the deposition surface, whether on the mold itself or on a layer of material already deposited, and thus minimize the number of orientation changes of the deposition head for the same deposition. Furthermore, the adaptability to the actual curvature of the deposition surface makes it possible to take into account a deposition surface whose curvature evolves along a given placement path.

[0028] The head according to the invention also makes it possible to minimize the number of passes of the head over a given deposition surface, making it possible to reduce the complete wear of the head movement system, reduce the time required to obtain the same part as well as to minimize the energy consumed during the deposition operation. BRIEF DESCRIPTION OF THE FIGURES

[0029] Other advantages and features of the invention will become apparent upon examination of the description and drawings in which: - [Fig. 1] schematically represents the placement device for the deposition head according to the invention; - [Fig.2] schematically represents the head placement device deposit conforming to the invention; - [Fig.3] schematically represents the front face of the placement device of the deposition head according to the invention - [Fig.4] schematically represents the deposition head according to the invention; - [Fig.5] schematically represents the deposition head in use according to a first position conforming to the invention; - [Fig.6] schematically represents the deposition head in use according to a second position according to the invention; - [Fig.7] schematically represents the deposition head in a profile view in accordance with the invention; and - [Fig. 8] schematically represents an enlarged portion of the feeding mechanism for the deposition head according to the invention; and - [Fig.9] schematically represents the guiding means of the device placement of the deposition head according to the invention. DETAILED DESCRIPTION

[0030] With reference to Figures 1 to 9, the automatic composite material strip 2 deposition head according to the invention comprises a composite material feeder configured to store at least one composite material strip 2 in the form of reels, a feeding mechanism 4 for bringing the strip 2 along a path extending from the composite material feeder to a placement device 3, a cutting mechanism 5 capable of cutting the composite material strip 2 to a chosen length, and a placement device 3 being capable of placing and compacting the composite material strip 2 on a deposition surface such as a mold 100.

[0031] The head placement device 3 according to the invention comprises a compaction mechanism 6, said compaction mechanism 6 comprising a support 8 on which are mounted at least three compaction rollers 61, 62, 63.

[0032] In practice, the compaction mechanism 6 comprises at least one central roller 61, and at least two peripheral rollers 62,63 coplanar arranged behind and laterally with respect to the central roller 61.

[0033] According to a particular embodiment according to the invention, the compaction rollers 61, 62, 63 are arranged in a V-shaped formation, in which the central roller 61 is located in front of the peripheral rollers 62, 63 in a direction of progression of the deposit head at the level of the deposit surface of the mold 100 and the peripheral rollers 62, 63 are arranged coplanarly.

[0034] The compaction mechanism 6 includes first of all at least one fixed central roller 61 attached to the placement device 3, said central roller 61 having an axis of revolution X perpendicular to an axis Y representing the normal orientation of the placement device 3 with respect to a deposit surface.

[0035] The compaction mechanism 6 then includes at least two peripheral rollers 62,63 arranged behind and laterally with respect to the central roller 61, each peripheral roller 62,63 being self-adjusting radially along a plane coplanar to an XY plane in response to a change in the inclination of the mold deposition surface 100 on which compaction is implemented for this peripheral roller 62,63.

[0036] Each peripheral roller 62,63 includes at least one right position, according to which it has an axis of revolution X' parallel to the axis of revolution X of the central roller 61 and perpendicular to the axis Y.

[0037] Each peripheral roller 62, 63 further comprises an adjusted position according to which it has an axis of revolution X” inscribed in a plane X'Y coplanar with the XY plane and having a chosen adjustable inclination with respect to to the X' axis function of the radial adjustment made in response to a change in the inclination of the mold deposition surface 100.

[0038] According to one embodiment of the invention, the axis of revolution X” is perpendicular with respect to the normal of the deposition surface on which said peripheral roller 62, 63 is fitted.

[0039] In practice, each peripheral roller 62, 63 is pivotally mounted on the support 8 of the placement device 3 via a fixed proximal end 641,651 attached to the support 8.

[0040] Each peripheral roller 62, 63 further has a distal end 642,652 which is radially movable along the X'Y plane and on which translation means 7 are mounted.

[0041] By way of example, the distance separating the proximal end 641, 651 from each peripheral roller 62, 63 is less than the length of the central roller 61.

[0042] Said translation means 7 comprise a fixed end 71 attached to a central attachment zone 73 of the support 8, and a movable end 72 in translation, attached to the distal end 642, 652 of each peripheral roller 62,63, said translation means 7 being configured to radially adjust each peripheral roller 62,63 by varying the inclination of the axis of revolution X” with respect to the axis X' in the X'Y plane, and thus maintain a chosen applied force when said peripheral rollers 62,63 are radially self-adjusting.

[0043] By way of non-limiting example, the translation means 7 are of pneumatic type, preferably of cylinder type.

[0044] According to one embodiment of the invention, each cylinder of the translation means 7 includes a long stroke, on the order of 50mm, allowing it to absorb the differences between the actual part and the programmed trajectory of the depositing head.

[0045] According to a particular embodiment of the invention, the central roller 61 also has translation means 7 mounted perpendicularly to the axis of revolution X of said central roller 61 and configured to ensure regulation of the force exerted by the central roller 61 on the band 2 of composite material during deposition.

[0046] In practice, the translation means 7 have pneumatic control following at least one setpoint value of compaction pressure chosen maintained continuously over the entire length of the strip, said pneumatic control being configured to be self-regulating if a measured pressure value exceeds a given threshold range.

[0047] Advantageously, the pneumatic control of the translation means 7 of each peripheral roller 62,63 is individually controlled.

[0048] By way of example, the pneumatically type translation means 7 comprise, for each peripheral roller 62, 63, an air supply whose pressure is between 5 and 7 bar, a filtration system, an accumulator to ensure the responsiveness of the air regulation, and a manual pressure regulator to guarantee pressure smoothing in the translation means 7 and thus ensure precise control of the force applied to each of the peripheral rollers 62, 63. The translation means 7 also have at least one controllable solenoid valve configured to control the translation towards the deposit surface and from the deposit surface towards the deposit head of the moving end 72.

[0049] In practice, the deposition head includes processing means configured to convert a setpoint force parameter to be applied in Newtons, into an equivalent pressure value.

[0050] The processing means are further configured to send at least one compaction command to the controllable pressure regulator.

[0051] The compaction command includes at least one control command for the pressure sent into an upper chamber of the cylinder, the cylinder having a lower chamber at atmospheric pressure during the compaction action, a constant back pressure is created in the cylinder.

[0052] Advantageously, the precise regulation of this counter-pressure allows the precise self-adjustment of the force exerted on the band 2 of composite material by each peripheral roller 62, 63 for the chosen inclination of the X” axis.

[0053] According to one embodiment of the invention, the regulation of the translational stroke of the translational means 7 and of the pressure in the pneumatic translational means 7 is dissociated, and allows for more precise adjustment of the position of each peripheral roller 62.63 and the applied force.

[0054] According to one embodiment, the regulation of the translational stroke of the translational means 7 and of the pressure in the pneumatic translational means 7 is dissociated and controlled jointly.

[0055] According to a first embodiment, the force applied on the central roller 61 and on the peripheral rollers 62,63 is substantially equal during deposition.

[0056] According to an alternative embodiment, the force applied to the central roller 61 is greater than the force applied to the peripheral rollers 62,63.

[0057] By way of example, the force applied to the composite material strip 2 is variable depending on the material used and the trajectory of the deposition head and is between 20 Kg and 100 Kg.

[0058] Advantageously, the pneumatic control as described allows the compaction pressure to be maintained continuously at a stable value according to the setpoint and allows pneumatic self-regulation of each peripheral roller 62, 63 along the entire length of the belt 2, taking into account surface imperfections on the workpiece such as an imperfection on the mold, an irregularity of the belt 2, a crushing of the resin or a variation in the thickness of the strip compared to the calculated theoretical thickness.

[0059] According to one embodiment of the invention, the placement device 3 further includes guiding means 43 for the strip 2 of material to be deposited.

[0060] These guiding means 43 are arranged upstream of the compaction mechanism 3 in the direction of feeding of the belt 2, and are suitable for guiding the belt to said compaction means 6.

[0061] The guiding means 43 include, but are not limited to, a fixed part 431, arranged centrally and a movable part 432 radially arranged laterally on each side of the fixed part 431.

[0062] The fixed part 431 includes at least one contact surface 434 projecting in the direction of the path of the strip 2, said contact surface 434 being configured to allow contact with the strip 2.

[0063] The movable part 432 includes on each side of the fixed part 431, at least one contact surface 434 disposed on the lateral end a support 435 configured to allow contact with the band 2.

[0064] The support 435 is pivotally mounted 433 to the fixed part 431 and has a lateral end mounted with a connecting rod mounted on the fixed part 431 and capable of moving the lateral end from a low position, in which each contact surface 434 of each moving part 432 is aligned with the contact surface(s) 434 of the fixed part 431, to a high position in which each contact surface 434 of each moving part 432 is raised relative to the contact surface(s) 434 of the fixed part 431, and vice versa.

[0065] The lateral end making a radial movement in the XY plane.

[0066] The high position allows a twist to be applied to the strip before placement to prevent it from disengaging due to gravity in certain placement angles, particularly when the placement surface is vertical.

[0067] In practice the contact surfaces 434 are fixed, and have an external layer covered with a non-adherent material such as Teflon.

[0068] According to a particular embodiment of the invention, the cutting mechanism 5 of the deposition head is suitable for cutting the strip 2 of composite material according to a chosen length and is of the straight cut type.

[0069] The deposition head according to the invention is configured to operate with a tape 2 of composite material in the form of a reel loaded into the composite material feed belonging to the group formed by pre-impregnated carbon fiber tapes conditioned on a support, pre-impregnated unidirectional carbon fiber tapes conditioned on a support, pre-impregnated glass fiber tapes conditioned on a support, other pre-impregnated fiber tapes.

[0070] According to one embodiment of the invention, the strip 2 of material to be deposited has a width of between 300mm and 500mm.

[0071] According to a preferred embodiment of the invention, the strip 2 of material to be deposited has a width of 400mm.

[0072] According to a preferred embodiment of the invention, the strip 2 of material to be deposited has a thickness of 0.6 mm.

[0073] The feeding of the deposition head according to the invention for storing at least one strip 2 of composite material comprises a first reel 21 configured to integrate a roller from which the strip 2 of composite material is conveyed.

[0074] The feed further includes means for separating the strip 2 of material with a protective film, said protective film being recovered by a second reel 22.

[0075] The strip 2 is then conveyed via the feeding mechanism 4 along a path extending from the feed through the cutting mechanism 5, and to the placement device 3.

[0076] In practice, the feeding mechanism 4 comprises a gripper 42 that moves in translation along a defined path between the feed and the cutting mechanism 5 via translational conveying means 4L

[0077] The clamp 42 is configured to move from a high position in which the clamp 42 is disposed on an end close to the feed, to a low position in which the clamp 42 is close to the cutting mechanism 5, and vice versa.

[0078] The clamp 42 is further configured to move from an open position in which the strip 2 of material passes freely through the clamp 42 and a closed position in which the strip 2 is immobilized between at least one support 421 and at least one counter-support 422.

[0079] By way of non-limiting example, the counter-support 422 includes a contact surface with the band 2 whose coating is of the Teflon type in order to minimize the adhesion of said band 2.

[0080] In practice, the support(s) 421 are arranged linearly along the length of the strip 2, and each has a reduced contact area with the strip 2, less than 1cm2-2cm2.

[0081] The clamp 42 further comprises at least one pair of rollers 423, each roller 423 being arranged coplanarly and close to each other in the upper position of the support 421 and the counter-support 422, so as to allow the passage of the strip 2. Advantageously, when the clamp 42 moves from a closed position to an open position, the strip bears against at least one roller 423 and makes it possible to induce a tension in the strip 2 sufficient to detach the surface of said strip 2 from the support 421.

[0082] The cutting mechanism 5 of the head according to the invention includes straight cutting means adapted to cut the strip 2, and a fixed clamp adapted to immobilize the strip 2 to allow cutting, the fixed clamp being adapted to move from an open position according to which the strip 2 of material passes freely and a closed position according to which the strip 2 is immobilized, and vice versa.

[0083] The deposition head according to the invention therefore makes it possible to reduce the number of trajectories required to depose a given surface, while allowing the use of a material of greater thickness than the thicknesses normally used and also makes it possible to increase the productivity of the composite material deposition process and less time-consuming while allowing to satisfy deposits on surfaces having curved profiles up to half-cylinders.

Claims

Demands

1. Automatic deposition head for composite material strips onto a mold surface (100), the head comprising: - a placement device (3) for placing a composite material strip (2) onto the mold surface (100); - a feeding mechanism (4) for bringing the strip (2) along a path extending from a composite material feed to the placement device (3); - a cutting mechanism (5) capable of cutting the composite material strip (2) to a chosen length;and in that the placement device (3) further comprises a compaction mechanism (6), said compaction mechanism (6) being characterized in that it comprises at least three compaction rollers (61, 62, 63), of which: - a fixed central roller (61) integral with the placement device (3), said central roller (61) having an axis of revolution X perpendicular to an axis Y representative of the orientation of the placement device (3) with respect to a mold deposition surface; and - at least 2 peripheral rollers (62, 63) arranged rearward in a direction of progression of the deposition head at the level of the deposition surface of the mold (100) and laterally with respect to the central roller (61), each peripheral roller (62, 63) being self-adjusting radially along a plane coplanar to an XY plane in response to a change in the inclination of the deposition surface of the mold (100) on which compaction is implemented for this peripheral roller (62, 63).;

2. Deposition head according to claim 1, characterized in that the compaction rollers (61,62,63) are arranged in a V-shaped formation.

3. Deposition head according to claim 1 or 2, characterized in that each peripheral roller (62, 63) is pivotally mounted on the placement device (3) via a fixed proximal end (641, 651) integral with the placement device (3), and having a distal end (642, 652) movable radially in a plane coplanar with an XY plane on which translation means (7) are mounted, said translation means (7) comprising a fixed end (71) and an end integral (72) with the distal end distal (642, 652) of each peripheral roller (62,63), said translation means (7) being configured to radially adjust each peripheral roller (62,63) along the plane coplanar to an XY plane and maintain a chosen applied force when said peripheral rollers (62,63) are radially self-adjusting.

4. Deposition head according to claim 3, characterized in that the translation means (7) are of pneumatic type.

5. Deposition head according to claim 4, characterized in that the translation means (7) have pneumatic control following at least one setpoint value of compaction pressure chosen, said pneumatic control being configured to be self-regulating if a measured pressure value exceeds a given threshold range.

6. Deposition head according to claim 5, characterized in that the pneumatic piloting of the translation means (7) of each peripheral roller (62,63) is individually self-regulated.

7. Cutting head according to any one of the preceding claims characterized in that the distance separating the proximal end (641, 651) from each peripheral roller (62,63) is less than the length of the central roller (61).

8. Deposition head according to one of the preceding claims, characterized in that the cutting mechanism (5) is of the straight cut type.

9. Deposition head according to one of the preceding claims, characterized in that the strip (2) of material to be deposited has a width between 300mm and 500mm.

10. Cutting head according to claim 9, characterized in that the strip (2) of material to be deposited is 400mm wide.

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