DEVICE FOR UNWINDING A THREAD FROM A SPOOL

Description

technical field

[0001] This document relates to a device for unwinding a wick from a coil for a filament winding installation capable of winding at least one wick from a coil around an object such as a hollow mandrel intended to form a reservoir which can, for example, receive pressurized fluid, such as, in particular, hydrogen gas. Previous technique

[0002] Filament winding is a process for manufacturing composite materials into parts with an axis of revolution (cylinder, cone, etc.) using molding. This process is suitable for mass production and is mainly used to manufacture parts subjected to high mechanical stresses (tanks, pipes, etc.).

[0003] There figure 1This represents a filament winding installation 10, according to a known technique, comprising a mandrel 12 mounted for rotation on a frame 14 and about a substantially horizontal longitudinal axis A. The installation 10 includes a reel 16 movable in translation along the longitudinal axis A and carrying a plurality of reels 18 extending substantially perpendicularly to a panel of the reel and substantially horizontally. Each reel 18 comprises a strand 20, which are joined end-to-end at a dispensing head 22 to form a sheet. The dispensing head 22 is attached to the reel 16 by means of a carriage 24 movable in translation along the longitudinal axis A.

[0004] In certain configurations (not shown), the dispensing head can also move in a direction transverse to the axis of the chuck, rotate around said transverse axis, pivot around the longitudinal axis, or even move on the vertical axis.

[0005] Before starting the filament winding system, the fiber sheet is attached to the mandrel. The reel tensioners are activated to tension the fibers, minimize sagging, and compact the successive layers as best as possible. A layer is defined by a winding that deposits the fiber sheet over the entire surface of the mandrel to be covered. A helical layer can be created by depositing the fiber sheet in a spiral pattern to cover the entire surface of the cylinder and specific areas within hemispherical ends. A circumferential layer can also be created, where the fiber sheet is deposited almost perpendicular to the mandrel axis over all or part of the cylindrical area of ​​the mandrel.

[0006] Filament winding allows for the stacking of successive helical and / or circumferential layers to achieve the desired mechanical properties of the object. Generally, the machine is controlled by a numerical control system. This numerical control is often programmed by an operator using software specifically designed for filament winding.

[0007] We know of contact dispensing machines that allow the dispensing of short ribbons without risk of twisting. However, these machines do not allow the dispensing and holding of long, continuous fibers under tension or axial mechanical stress in the fiber direction that is imposed and regulated.

[0008] The known processes of this type are ATL for Automated Tape Layer and AFP for Automated Fiber Placement.

[0009] The ATL process uses wide tapes (generally 100 to 300 mm). This technique allows deposition on large, low-radius surfaces such as civil aircraft wings. The AFP process uses a juxtaposition of tapes less than 10 mm wide and assembles up to 32 tapes at the output of the printing head.

[0010] The main applications are the production of flat parts or parts with a large radius of curvature. The core idea is to replace manual labor for laying successive folds with defined fiber orientations.

[0011] All current systems use calibrated prepreg tapes (fiber / resin) with a separation film between the layers on the storage reel. These calibrated tapes are made from recut unidirectional prepreg sheets, which carries the risk of partially cutting the reinforcement at the edges. Material costs are significant, and a winding system for the separation film is necessary during draping operations.

[0012] None of these systems use standard prepreg fibers, meaning those without a separating film between layers for filament winding. It is not possible to apply continuous tensile tension (or stress) (in the direction of the fiber) to the strands because the strand(s) forming the web are cut at each end of the finished part.

[0013] To date, successive developments in the field of composite material implementation have largely focused on process automation. These developments are driven by the significant needs expressed in the automotive and aerospace sectors. The development of hydrogen storage technologies (for example, at 700 bar operating pressure), coupled with increasing gravimetric capacity (i.e., the ratio between the amount of hydrogen stored and the mass of the container), is pushing the limits of composite materials' applications.

[0014] Traditional filament winding processes (dedicated machines) and more automated methods (versatile machines) have never fully considered the impact of the process on performance loss. In most cases, the spool support is located far from the dispensing head, and the filaments pass through a significant number of guides and rollers before reaching the dispensing head.

[0015] Currently, filament winding systems (from the spools that store the material) on filament winding machines are designed without considering the effects of unwinding on the filament's geometry and mechanical performance. Most systems, whether mechanical (fixed tension applied to the filament) using springs or belts, or electronic (modulated tension applied to the filament), are simply filament unwinding systems. However, the filament on each spool is wound onto the spool's spool shaft at a cutting angle that induces movement along the shaft. When the spool's output guide is a guide rod, the filament moves along the rod. When the output guide is a guide roller, the filament forms an angle oscillating around 90°.In both cases, the movement of the drill bit relative to the return element is likely to twist the drill bit, which can lead to manufacturing defects when the drill bit is placed on the chuck.

[0016] This problem is further exacerbated when the spool wick is pre-impregnated with a partially polymerized, curable matrix such as a thermosetting or thermoplastic matrix. Indeed, the tackiness greatly limits, or even prevents, wick slippage, thus hindering any movement that could limit twisting once it has begun.

[0017] To limit the formation of twists, it is known to move the reels away from the return elements and therefore from the dispensing head, which poses a problem of the footprint of the filament winding machine.

[0018] US documents 2018 / 037433 A1 and JP S58 109227 A disclose a winding device according to the preamble of claim 1. Summary

[0019] A device for unwinding a wick from a spool is proposed, comprising: a platform carrying at least one reel holder extending along an axis substantially perpendicular to the platform and intended to receive a reel capable of rotating around said axis of the reel holder; means for moving the reel in translation along the axis of the reel holder; means for controlling the means of movement configured to allow the exit wick of the reel to be maintained at a substantially constant axial position, i.e. along the axis of the reel holder.

[0020] Controlling the spool's movement maintains the geometry of the spool's unwinding strand. It's understood that the spool's axial position isn't strictly constant in the mathematical sense, but it's kept substantially constant so that its position appears constant and prevents twisting.

[0021] The coil can be a wick coil made of a plurality of reinforcing fibers or filaments. The fibers can be carbon fibers.

[0022] The means of movement may include means for guiding in translation a connecting piece along an axis parallel to the axis of the reel holder, this connecting piece being connected to a reel support surrounding the reel holder, the reel support being coupled in rotation to the reel holder and free in translation along the reel holder.

[0023] The connecting piece can be connected in rotation around the longitudinal axis to the reel support and be fixed in translation along said axis of said reel support.

[0024] According to another characteristic, the guiding means may include at least one rod substantially perpendicular to the plate and in which the connecting piece is guided by sliding motion.

[0025] The means of movement may include a motor coupled in rotation by a belt to a worm gear driving the connecting part in translation.

[0026] The reel holder can be mounted to rotate relative to the connecting piece.

[0027] A bearing support can be mounted at the junction of the spool support and the connecting piece.

[0028] The spool holder includes ball bearings for the translational movement of the spool support.

[0029] The spool holder can be mounted to rotate on the platter.

[0030] The control means may include means for detecting the axial position of the wick exiting the coil.

[0031] The detection means may include two position sensors, for example of optical or other type, spaced axially apart from each other and configured to detect the passage of the drill bit.

[0032] Installation for winding at least one strand of a coil by means of a device according to one of the preceding claims. Brief description of the drawings

[0033] Other features, details, and advantages will become apparent upon reading the detailed description below and analyzing the attached drawings, on which: [ Fig. 1 ] there figure 1 , already described previously, is a schematic perspective view of a filament winding installation according to the prior art; Fig. 2 ] there figure 2 And [ Fig. 3 ] there figure 3 are schematic perspective views of a device according to this document, in two different orientations; [ Fig. 4 ] there figure 4 is a schematic perspective view of the spool holder with an enlargement on the right side of the area outlined in dotted lines; Fig. 5 ] there figure 5 is a schematic perspective drawing of a spool holder and a spool support surrounding the spool holder; Fig. 6 ] there figure 6 is a schematic view similar to that of the figure 5 in which the spool holder has been removed; [ Fig. 7 ] there figure 7 is a schematic perspective view of the spool holder with an enlargement on the right side of the area outlined in dotted lines, a partial section being made to show the connection between the connecting piece and the spool support; [ Fig. 8 ] there figure 8, is a schematic perspective view of a reel unwinding device mounted on a reel holder which is in a first position in figure 8A and in a second position 8B. Description of the implementation methods

[0034] We now refer to the figure 2 which represents a device 28 unwinding according to this document and which includes a plate 30. It is observed that a reel 31 is carried by the plate 30 and on one side which is opposite to that intended to support a depositing head (not shown).

[0035] The platform 30 thus includes one coil 31 but could carry several. The coil(s) 31 extend along a longitudinal axis A which may be parallel to the longitudinal axis of the dispensing head. Reference will now be made to a single coil 31, although the platform 32 may contain several.

[0036] The device 28 comprises a spool holder 32 surrounded by a spool support 36, the spool 31 being rotationally fixed to the spool support 36, for example by a clamping or any other suitable mounting. The spool holder 32 and the spool support 36 are coaxial along an axis A substantially perpendicular to the plate 30.

[0037] The device 28 includes means 34 for moving the spool 31 in translation along the axis A of the spool holder 32 and means 41 for controlling the movement means configured to allow the wick 37 to be held ( figure 8 ) of the coil 31 to a substantially constant axial position.

[0038] The movement means 34 include means for guiding the translation of a connecting piece 38 attached to the reel support 36 31. This connecting piece 38 has an upper portion 38a for translational sliding, through which pass two rails 40 or guide rods parallel to the longitudinal axis A of the reel holder 32. The upper portion 38a is adapted to slide on the two rails 40. The upper portion 38a of the connecting piece 38 is connected to a bracket 38b, the end opposite the upper portion 38a of which is rotationally connected to the reel support 36 31 and is fixed in translation along said axis A of said reel support 36 31, as will become clearer in relation to the figures 4 to 7The drive means 34 comprise a motor 42 whose output shaft 44 is rotationally coupled by a belt 46 to a worm gear 48 which drives the connecting part 38 in translation. More specifically, the worm gear 48 passes through the upper part 38a of the connecting part 38 and is rotationally coupled to it via a thread so that the rotation of the worm gear 48 causes the connecting part 38 to move in translation along the longitudinal axis A, and consequently the spool support 36 and therefore the spool 31.

[0039] On the figure 3 We observe the presence of a motor 45 intended to generate tension in the wick 37 of the coil 31. The output shaft 47 of this motor 45 is coupled to the coil holder 32 by a belt 51. A tensioner could be used to tension the belt 46 and / or the belt 51.

[0040] We now refer to figures 4, 5 and 6which illustrate the reel support 36 for reel 31 coupled in translation to the bracket 38b of the connecting piece. The reel support 36 for reel 31 is mounted in translation along the longitudinal axis A on the reel holder 32 and is able to slide along said longitudinal axis A on the reel holder 32. The reel support 36 for reel 30 is coupled in rotation to the reel holder 32 by means of a corresponding form. More specifically, the inner face of the spool support 36 for the spool 31 includes longitudinal ribs 36a engaged in longitudinal grooves 32a of the spool holder 32. The spool holder 32 includes ball bearings 50 for the translational movement of the spool support 36 for the spool 31 on the spool holder 32. In this way, the spool holder 32 is rotationally connected to the spool support 36 which carries the spool 31, and the spool support 36 for the spool 31 can slide on the spool holder 32.

[0041] To ensure rotation of the coil support 36 relative to the fixed connecting piece 38, a bearing is formed at the annular junction of the bracket 38b and the coil support 36. This bearing can be formed by an annular flange 52 of the coil support 36 mounted in an annular groove of the bracket 38b. It can thus be a plain bearing. It would also be possible to achieve a connection by means of a rolling bearing with an outer ring integral with the bracket 38b and with an inner ring integral with the coil support 36. figure 7 ).

[0042] In order to control the motor 42 for the translational movement of the support 36 for the coil 31, the control means 41 include means 41a for detecting the axial position of the wick 37 exiting the coil 31, these detection means including, for example, two optical position sensors 41a spaced longitudinally apart and configured to detect the passage of the wick 37. These optical sensors 41a can be carried by a rod 54 parallel to the longitudinal axis A ( figure 8 ).

[0043] There figure 8This illustrates two positions along the axis A of the spool 30 and therefore of the spool support 36. It can be observed that with the device 28 according to this document, the drill bit 37 always exits the spool 31 in a direction substantially perpendicular to the axis of the spool. The position of the drill bit along the longitudinal axis remains constant, which allows the use of a guide roller or a guide rod 56 without risk of twisting.

Claims

1. A device (28) for unwinding a strand from a bobbin (31) comprising: - a plate (30) supporting at least one bobbin holder (32) extending according to an axis (A) substantially perpendicular to the plate (30) and intended to receive a bobbin (31) able to rotate around said axis of the bobbin holder (32); - movement means (34) for translationally moving the bobbin according to the axis of the bobbin holder (32); - control means (41) for controlling the movement means (34) configured to enable maintenance of the strand (37) leaving the bobbin (31) at a substantially constant position along the axis (A) of the bobbin holder (32), wherein the movement means (34) comprise guide means for guiding a connecting part (38) in translation according to an axis parallel to the axis of the bobbin holder (32), characterized in that this connecting part (38) is connected to a bobbin support (36) surrounding the bobbin holder, the bobbin support (36) being coupled in rotation to the bobbin-holder (32) and free to translate along the bobbin holder (32).

2. The device according to claim 1, wherein the connecting part (38) is connected in rotation about the longitudinal axis (A) to the bobbin support (36) and is secured in translation along said axis (A) with said bobbin holder (36).

3. The device according to claim 1 or 2, wherein the guide means comprise at least one rod (40) substantially perpendicular to the plate (30) and in which the connecting part (38) is slidably guided.

4. The device according to one of claims 1 to 3, wherein the movement means (34) comprise a motor (42) coupled in rotation by a belt (46) to a worm screw (48) driving the connecting part (38) in translation.

5. The device according to one of claims 1 to 4, wherein the bobbin holder (32) is rotatably mounted relative to the connecting part (38).

6. The device according to claim 5, wherein a roller bearing is mounted at the junction of the bobbin support (36) and the connecting part (38).

7. The device according to one of claims 1 to 6, wherein the bobbin holder (32) comprises ball bearings for the translational movement of the bobbin holder (36).

8. The device according to one of the preceding claims, wherein the bobbin holder (32) is rotatably mounted on the plate (30).

9.

16. The device according to one of the preceding claims, wherein the control means (41) comprise means (41a) for detecting the axial position of the strand (37) leaving the bobbin (31).

10.

18. The device according to claim 9, wherein the detection means (41a) comprise two position sensors, for example optical, spaced axially apart from each other and configured to detect the passage of the strand (37).

11.

20. A unit for winding at least one strand of a bobbin by means of a device according to one of the preceding claims.