WO2018109347A1

WO2018109347A1 - Method and machine for bracing a part by winding a wire-like element under tension around said part

Info

Publication number: WO2018109347A1
Application number: PCT/FR2017/053496
Authority: WO
Inventors: Patrick LANCE
Original assignee: Lance Patrick
Priority date: 2016-12-12
Filing date: 2017-12-11
Publication date: 2018-06-21
Also published as: FR3059988A1; FR3059988B1

Abstract

The invention relates to a method for bracing a part by winding a wire-like element (8) under tension around said part. The invention likewise relates to a machine (1) for bracing a part by winding a wire-like element (8) under tension around said part. The method and the machine apply to bracing operations as well as to filament-winding or taping operations. The wire-like element is placed under tension before winding same around the part by passing the wire-like element at least once around at least one roller (11, 11a-11g) so as to generate a contact angle α between the wire-like element and the at least one roller of no less than 360° (α≥360°), and by applying a brake to the at least one roller so as to exert a torque on same. The invention can be used for bracing, filament winding or taping a part.

Description

METHOD AND MACHINE FOR FREQUENCING A WORKPIECE BY WINDING A WIRED ELEMENT ON A VOLTAGE AROUND THIS PIECE

TECHNICAL FIELD The present invention relates to the field of hooping a part by winding a filamentary element around this part, for example a cylinder, a cone, a fuselage or a part whose section is elliptical or has a contour of any convex shape with possible additional concavities, or other forms of parts that can undergo such a winding, said filamentary element being tensioned prior to its winding around said piece.

The invention relates to a method for shrinking a workpiece by winding the tensioned wire element around the workpiece and on a machine for shrinking a workpiece by winding the tension element around the workpiece. The method and the machine are particularly intended for producing a hoop, which also apply to the fields of filament winding and adhesive on a workpiece, areas for which it is necessary either to apply a high tension on the wire element (for hooping) is to perfectly control the voltage applied to the wire element (for filament winding and masking) during its winding around the piece, or both at a time. State of the art

It is known to make a hoop on a part to compensate the centrifugal forces exerted on it during its rotation. For example, a magnet rotor of an electric machine can be shirred to prevent the magnets from tending to deviate under the action of the centrifugal force generated during rotation of the rotor. It is also possible to shrink a flywheel made of concrete, or any other material, used on an installation to store energy for later retrieval. Indeed, when the flywheel rotates at high speed, the centrifugal force exerted on it can cause it to burst; the effects of the centrifugal force can be compensated by the establishment of a hoop for compressing the flywheel. A hooping of a cylindrical part can be achieved by placing a metal cylinder on the part of the part to be shrunk. The hoop (the metal cylinder) is heated so that it expands and is then placed on the part to be shrunk. The coin to be fretted possibly be cooled beforehand so that it retracts. When the temperature of the various elements is homogeneous again, the band puts in compression the fretted piece. There is then a prestressing in the hoop as well as in the fretted piece.

Another possibility is to wind a wire element under tension on the part to be fretted. Such hooping is similar to a filament winding, the voltage on the filament element is however greater than in the case of filament winding.

A filament winding generally consists of a molding of composite materials in the form of a hollow part. Such a part is generally subjected to a strong internal pressure. The filament winding consists in winding continuous fibers impregnated or pre-impregnated with resin around a rotating part acting as an inner mold. Such a part is generally called "mandrel" in the case of filament winding. The fiber removal head moves along the mandrel during its rotation so as to wind its threads according to the needs of the part. Once the filament winding is positioned around the mandrel and cures (by oven baking or other curing processes), the mandrel is extracted and the fabricated part is recovered. The applications are very varied, the manufactured parts can for example be a pipeline, a tank, a fishing rod, a fuselage.

Unlike the filament winding where the mandrel is extracted, the filament winding remains around the piece in the case of a hoop. A shrinking operation requires applying very high tensions on the filamentary element during its winding around the workpiece, said filament element being able to become damaged or broken, in particular when it consists of fibers. It is appropriate, in fact, that the voltages applied to the wire elements are high in order to provide a real prestressing on the parts to be fretted. By way of example, a stress greater than 500 MPa must be applied to an epoxy glass composite wire, ie a voltage greater than 500 Newtons on a 1 mm ² section wire.

In the textile field, unrelated to that of hooping, textile machines have devices that can lightly stretch textile threads with a regular tension, before assembling these son after they have undergone a twist. Titles EP0374059A1 and WO2005123557A1 disclose such textile machines. The stress applied to a filament element and the control of this constraint during an operation of hooping, or even filament winding or marouflage, are without measure with those necessary in the context of a twisting operation and assembly of textile threads.

Summary of the invention

The present invention aims to implement an operation of shrinking a workpiece by winding a wire element around the workpiece with a significant tensioning and perfect control of the tension of the wire element during its winding around the room, while avoiding its deterioration. The invention will also allow the implementation of a filament winding or a marouflage, operations for which the wire element is also energized and wound around a workpiece, with however a slightly lower voltage than in the case of hooping, but also requiring perfect control of this voltage during the winding of the wire element.

To this end, the invention relates first of all to a method of shrinking a workpiece by winding a tensioned wire element around this workpiece, for example a cylinder, a cone, a fuselage, or a workpiece whose section is elliptical or has any contour convex shape. The term "hooping" within the meaning of the invention covers both shrink-wrapping operations as such, and filament winding or masking operations which are similar to hooping.

According to the invention, the method comprises at least one step of transporting the wire element to the part and a step of winding the wire element around the part. This winding step may be carried out in two ways: either the part is rotated to wind the wire element around said part, or is rotated a satellite around the room, said satellite being provided with a depositing head for manipulating and guiding the wire element for winding around said part. In a preferred and quasi-general implementation, the wired element is unrolled as and when a coil, but one could consider a continuous manufacture of the wired element followed by the implementation of said process according to the invention. The unwinding of the wire element of the coil can be achieved either freely or by imposing a slight tension on it.

In addition, the method according to the invention comprises a step of tensioning the wire element before winding it around the workpiece. This step of tensioning is implemented: by performing at least one passage of the filament element around at least one roller so as to generate an angle of contact of the filament element with the at least one roller, greater than or equal to 360 ° (a> 360 °),

and by braking the at least one roller so as to exert a torque thereon, said torque being reversed in the direction of advance of the wire element, thereby allowing the wire element to be braked and put under voltage.

This implementation makes it possible to tension the wire element while preventing any slipping on the rollers so as not to degrade said wire element. This also avoids exerting a significant tension upstream on the element wire, that is to say before it passes over the at least one roller, which allows unwinding the filament element of the coil without exerting voltage, or very little, at this coil.

It is understood that when a single roller is used, the wire element will be wound on at least one turn around the roller, so as to obtain a contact angle greater than or equal to 360 °. On the contrary, when several rollers are used, the wire element will be wound partially one or more times on each of the rollers, so as to obtain a total contact angle a greater than or equal to 360 °.

According to a first embodiment of the method which is the subject of the invention, the wire element is wound around two rollers by carrying out at least one turn. The rollers are for example arranged vertically one below the other. The wire element is thus in contact with the upper part of the upper roller and with the lower part of the lower roller, when one carries out a turn of the wire element around the two rollers.

According to a second embodiment of the method which is the subject of the invention, the wire element is wound around at least two rollers, preferably five rollers staggered in two rows, making a single pass. The rollers are offset relative to each other in order to bring the element into contact with a portion of each of the rollers and to reach a total contact angle greater than or equal to 360 °.

According to a third embodiment of the method which is the subject of the invention, the wire element is wound around at least two rollers, preferably seven rollers staggered in three rows, making at least two passes. This third embodiment is similar to the second embodiment mentioned above, the only difference being that the arrangement of the rollers makes it possible to perform a return of the filament element to make several passes thereof on the rollers. According to the method of the invention, several passes are made around the at least one roller by shifting the wire element on said at least one roller during each passage, so that the wire element does not pass twice to same place on the same pebble. This avoids the deterioration of said wire element. In one embodiment of the method that is the subject of the invention, the wire element is a fiber-based yarn, for example carbon fibers or glass fibers, or even other fibers, said wire element being impregnated with a resin. before winding it around the room. The wire may be impregnated following its unwinding of the coil, or may be prepreg. One can also consider no impregnation of resin on the wire element. The wire may also be twisted prior to its passage around the at least one roller or by twisting it after being unwound or using a coil of already twisted wire. Twisting the wire increases the tensile force exerted on it.

In one embodiment of the method that is the subject of the invention, the wire element is impregnated with an excess of resin and then calibrated by passing through one or more successive gauges, before winding it around the part or before it passes over the rollers. .

In another embodiment of the method that is the subject of the invention, the wire element is a monofilament wire, for example a wire of steel, titanium or invar.

In another embodiment of the method that is the subject of the invention, the wire element is a plastic ribbon used for carrying out a marouflage operation on a part, for example to compact a composite part during its molding through plastic tape.

In one embodiment of the method that is the subject of the invention, the torque exerted on the at least one roller is reduced so as to reduce the tension on the wire element, during the winding of said wire element near the edges of the winding. on the piece. This operation makes it possible to prevent sagging of the wire element on the edges of the part, in particular in the case of a hooping on a part having no flanges on its edges to contain the firette which exerts significant tensions.

The invention also relates to a room hooping machine by winding a wired element under tension around a workpiece. As specified above for the process, the term "hooping" in the sense of the invention covers both the hooping machines as such, and filament winding machines or masking which are similar to hooping. According to the invention, the machine comprises: a system for winding the wire element around the part,

a support system for a coil on which the wire element is wound, said support system being configured to allow unwinding of the wire element of the coil, with a view to its winding around the part of the part,

a tensioning system of the wire element disposed between the coil support system and the winding system of the wire element around the workpiece, said tensioning system comprising:

At least one roller configured so that the filament element makes at least one passage around the at least one roller by generating an angle of contact of said filament element with said at least one roller, greater than or equal to 360 ° (a > 360 °),

• a braking device of the at least one roller so as to exert a torque thereon, thereby braking the wire element and turn it on. In one embodiment of the machine according to the invention, the winding system of the wire element around the workpiece is implemented by means of a workpiece support system, said system being configured to drive said workpiece in rotation. piece around its axis of revolution. However, it is possible to envisage an embodiment variant according to which said winding system comprises a satellite and means for rotating the satellite around the part, said satellite being configured to hold the element during its winding around the part. generated by the rotation of said satellite.

In an implementation of the machine according to the invention, the tensioning system comprises two rollers configured to perform at least one passage of the wire element. According to one variant, the tensioning system comprises at least two rollers configured to perform a single passage of the filament element. According to another variant, the tensioning system comprises at least two rollers configured to perform at least two passages of the filament element.

In an implementation of the machine according to the invention, the braking device comprises

gear means configured between the rollers for driving them concomitantly in rotation with the same speed of movement of the filamentary element on these rollers, the directions of rotation of the rollers corresponding to the direction of movement of the filamentary element during its passage over these rollers;

braking means of one of the rollers, the gear means automatically causing the braking of the other rollers. These braking means can act directly on one of the rollers or indirectly through a shaft secured to the roller or even through the gear means in connection with said roller.

One could however consider another variant of providing synchronized braking means on each of the rollers, without requiring the use of gear means. According to the invention, the machine comprises a system for moving the wire element along the axis of revolution of the part. This displacement system makes it possible to wind in a controlled manner the filament element around the part.

According to the invention, the machine may comprise a twisting system of the wire element arranged upstream of the tensioning system. This makes it possible to twist said wire element to make it more resistant before it is put into tension.

According to the invention, the machine may comprise a system for impregnating a resin on the wire element before winding it around the part. Preferably, this impregnation system is positioned at the output of the coil, before the tensioning of the wire element by means of the tensioning system. However, it is possible to position this impregnation system between the tensioning system and the part, in a variant embodiment.

According to the invention, the machine comprises means for measuring the torque exerted on the at least one roller and / or on the part, as well as means for controlling the braking device of the at least one roller configured to adjust said braking as a function of the torques measured on the at least one roller and / or on the part. Preferably, these means for controlling the braking device of the at least one roller are configured to adjust said braking as a function of the position of the wire element along the part. Preferably the machine comprises means for measuring the torque exerted on the at least one roller and means for measuring the torque exerted on the part. However, it would be possible to envisage an alternative machine comprising only one or the other of the above-mentioned torque measurement means, or even any other system for measuring the voltage on the wire element.

Thus, the method and the machine according to the invention allow the implementation of a hoop, a filamentary winding or a marouflage on a piece. Brief description of the figures

The features and advantages of the invention will appear on reading the following description of a preferred embodiment based on figures, among which:

Figure 1 shows a first embodiment of a machine according to the invention in top view;

Figure 2 shows schematically the coil, the tensioning system and the workpiece on the machine of Figure 1 during the winding of the wire element around said part;

Figure 3 shows schematically the passage of a wire element on a roller, so as to highlight the contact surface and the contact angle between said elements;

FIGS. 4 and 5 schematize two embodiments of a tensioning system comprising two rollers;

FIG. 6 schematizes a five-roller tensioning system, the wire element performing a single passage in said system;

FIG. 7 schematizes a seven-roller tensioning system, including two return rollers, the wire element performing at least two passes in said system;

Figures 8 and 9 show schematically another embodiment of a tensioning system having two rollers;

Figure 10 shows a second embodiment of a machine according to the invention in top view. detailed description

In the rest of the description, the same references are used to define the same characteristics or their equivalents, according to the various variants.

In FIG. 1, the machine 1 comprises a first support system 2 of a part 3. In FIG. 1, this part 3 is of cylindrical shape, but other forms of revolution are possible, for example a cone or a fuselage. Other forms may also be envisaged, for example a part having a section in a plane of section perpendicular to the axis of revolution XI of elliptical shape or any other convex shape. When the machine 1 is used to perform a shrinking operation, the part 3 constitutes the part to be shrunk, for example a rotor, a flywheel, a centrifuge. Similarly, when the machine 1 is used to perform a marouflage operation, the part 3 is the piece to be rubbed, for example a composite tube. While when machine 1 is used for an operation filament winding, this piece 3 is the cavity or the internal mold of the part to be manufactured, for example a tank, a pipe.

The support system 2 of the workpiece 3 comprises a motor 4 and holding means 5 of the workpiece 3, these holding means 5 consisting for example of a mandrel (not shown) attached to the motor 4 and a tailstock (Not shown) to maintain the workpiece 3 along its axis of revolution XI and rotate it along the axis of revolution XI under the action of the motor 4.

The machine 1 also comprises a second support system 6 of a coil 7 on which is wound a wire element 8. The support system 6 comprises for example a shaft 9 which keeps the coil 7. This shaft 9 can be fixed and pivotably receiving the coil 7 along its longitudinal axis X2 so as to allow it to rotate freely along this longitudinal axis X2 which, in FIG. 1, is parallel to the axis of revolution XI of the piece 3. It is also possible to envisage a tight fitting between the shaft 9 and the coil 7 so as to secure said elements, said shaft 9 rotating freely or being rotated at a speed controlled by a motor (not shown) on said support system 6. It is also possible to envisage a brake (not shown) on this support system 6 for braking either the shaft 9 is directly the coil 7, according to the aforementioned implementation cases. The aforesaid motor and brake are each intended to control the filament element 8 which unravels, exerting a slight tension thereon. We can also consider other orientations of the longitudinal axis X2 of the coil 7 vis-à-vis the axis of revolution XI of the part 3. It is also possible to uncoil the wire element 8 while maintaining the coil 7 fixed, pulling the wire element 8 in the direction of the longitudinal axis X2 of the coil 7. In Figure 1, the wire element 8 is unwound from the outside of the coil 7; it is however possible to provide variants with a fixed coil 7, the wire element 8 being unwound by the center of the coil 7 by pulling on said wire element 8 in the direction of the longitudinal axis X 2 of this coil 7.

As illustrated in FIGS. 1 and 2, the machine 1 also comprises a tensioning system 10 in which the wire element 8 passes before it is wound on the part 3. This tensioning system 10 makes it possible to transmit progressively the filament member 8 an effort not to damage it, which is essential especially for fiber-based son which are generally fragile.

FIG. 3 illustrates the essential principle of the tensioning system 10. In this FIG. 3 is illustrated the filamentary element 8 on which it is necessary to apply a tension during its winding on the part 3. The element 8 is in contact with a part of a roller 11 on a contact angle a. By applying a torque C on this roller 11, a force F1 is applied upstream on the wire element 8 uncoiling and a force F2 greater than the force F1 is applied to said wire element 8 wound on the piece 3. The difference between the forces F1 and F2 will depend on the torque C transmitted to the roller 11, the contact angle a and the coefficient of friction between the wire element 8 and the roller 11. By increasing the torque C, a limit of sliding of the wire element 8 on the roller 11. This sliding can be avoided by increasing the contact angle α between the wire element 8 and the roller 11, which ultimately allows to obtain a force F2 downstream high enough with a relatively low upstream Fl force, without slippage. In practice, for the applications sought according to the invention, particularly for shrinking operations, it is necessary to have a contact angle α which is greater than or equal to 360 °.

For the applications envisaged according to the present invention, especially for a wire element 8 of the fiber-based wire type, it is intended to implement this contact angle a greater than or equal to 360 ° by using several rollers 11 on the system. The use of a single roller 11, although possible, would require winding the wire element 8 on the roller 11 by performing several turns, which could damage the wire element 8 by ironing the one at the same location on said roller 11. The contact angle has greater than or equal to 360 ° is preferably obtained by using several rollers 11 rotating at scrolling speeds of the identical wire element and braked concomitantly to exert a couple on these rollers 11.

In FIG. 4, the tensioning system 10 comprises two rollers 1a-1b linked together by a set of gears 12 comprising three toothed wheels 12a-12c. The rollers 1 a-1 lb are of identical diameters and the gear set 12 rotates the two rollers 1 la-1 lb in the same direction with a transmission ratio equal to one (r = 1). The direction of rotation of the rollers 1 la-1 lb corresponds to the direction of movement of the wire element 8 for its winding around the piece 3. The gear set 12 makes it possible to brake only one of the two rollers 1 la-1 lb to transmit a torque distributed on each of said rollers 1 la-1 lb. Wire element 8 is wound on rollers 1a-1b through one or more passes, said wire element 8 being in contact with the upper part of first roller 11a and with the lower part of second roller 1b, as illustrated in this figure 4, which ensures a total contact angle of 360 ° during a passage. The rollers 1a-1b may comprise successive grooves (not shown) for shifting the wire element 8 on the rollers 1a-1bb when several passes are made, which avoids damage to the wire element 8. This can also be envisaged when a single roller 1 1 or more of two rollers 11 are provided on the tensioning system 10.

In FIG. 5, the principle of the tensioning system 10 is similar to that mentioned in FIG. 4, the difference being that the rollers 11 a-11b are inclined with respect to each other along non-parallel axes to ensure a natural shift of the wire element 8 during several passages around these rollers 11 a-11b. According to this variant, it will also be possible to provide a set of gearing adapted to take account of the inclination between the two rollers 1a-1b and a brake on one of the two rollers 1a-1b. It would also be possible to independently brake each of the rollers 1a-1b. In FIG. 6, the tensioning system 10 comprises five rollers 1a-1 which are staggered in two rows and make it possible to carry out a single passage of the filamentary element 8. The filamentary element 8 is in partial contact with each roller 1 la-1 the during its passage in the tensioning system 10, as shown in Figure 6, allowing the total to obtain a contact angle of 720 °, the equivalent of two The rollers 1a-1 are all of identical diameters and a set of gears 12, comprising five gears 12a-12e, ensures rotation at the same speed of all the rollers 1a-1 the with a transmission ratio equal to one (r = 1). Each roller 1 la-1 rotates in the direction of movement of the filament element 8 which passes successively on each roller 1 la-1. The braking of only one of the rollers 1a-1 allows it to brake the assembly to exert a torque distributed on each roller 11a-11e.

In FIG. 7, the design incorporates the characteristics of the tensioning system 10 of FIG. 6 and comprises, in addition, two rollers 1 lf, 1 lg of return making it possible to carry out several passes of the filamentary element 8 on said system of FIG. tensioning 10. The rollers 11a-11g are all of identical diameters and arranged in three rows. A set of gears 12, comprising seven gears 12a-12g, provides rotation at the same speed of all the rollers 1a-1g with a transmission ratio equal to one (r = 1). The braking of only one of the rollers 1 la-11g can brake the assembly to exert a torque distributed on each roller 1 la-1 lg. The wire element 8 is in partial contact with each roller 11a-11g during its passage through the tensioning system 10, as illustrated in FIG. 7, allowing a contact angle a of 1080 ° during an additional passage, the equivalent of three laps on a single roller 11.

In the aforementioned cases where a set of gears 12 provide the connection between all the rollers 11a-11g, the braking of one of said rollers is enough to brake them all. Braking of the roller is put implemented by means of a powder brake (not illustrated) which regulates the torque and the voltage on the wire element 8.

The machine 1 is equipped with a displacement system 13 configured to move the tensioning system 10 and the wire element 8 along the axis of revolution XI of the part 3 during its winding around said part. This displacement system 13 consists for example of a first carriage 13a mounted in sliding connection along a longitudinal axis X3 parallel to the axis of revolution XI of the part 3, said first carriage 13a supporting the tensioning system 10 and being driven by motor and auger (not shown). This displacement system 13 may also comprise, in addition to or in substitution for the first carriage 13a, a second carriage 13b on which is mounted a depositing head 17 configured to hold and guide the wire element 8 during its winding around the wire. piece 3, this second carriage 13b is also controlled in translation by a motor and a worm (not shown) along an axis parallel to X4 axis of revolution XI.

The machine includes a control system (not shown), including a programmable controller (not shown) and measurement sensors (not shown). The support system 2 of the workpiece 3 comprises a torque measuring sensor arranged on the rotation shaft of the motor 4, for measuring the tension exerted on the portion of the wire element 8 wound on the workpiece 3. Likewise, the tensioning system 10 comprises a torque measuring sensor arranged on one of the rollers 11 a-11 g, making it possible to measure the tension of the portion of the wire element 8 passing over the rollers 11a. - 11 g The displacement system 13 is equipped with a position measuring sensor (not shown) making it possible to measure the position of the filamentary element 8 wound on the part 3. The programmable controller controls the motor 4 driving the part 3 , the powder brake (not illustrated) for braking the rollers 11 a-11 g of the tensioning system 10 and the motor of the displacement system 13, in order to better adjust the speeds of these elements as a function of the desired tension on the wire element 8 during its winding on the part 3. In the case of a shrinking operation where high voltages are applied, the PLC will also adjust the braking of the rollers 1 la-1 1 g according to the position of the filament element 8 along the part 3, in particular for the purpose of reducing the tension on the filament element 8 on the longitudinal edges of the hoop used, in order to avoid sagging at the level of said longitudinal edges. Flanges may be provided on the longitudinal edges of the part 3 in order to contain the hoop during molding (uncured resin) but also in operation of the part 3. When no flange is provided in operating mode, Removable tools can play the role of flanges during the molding phase of the hoop. The machine 1 equipped with such a tensioning system 10 is particularly suitable for producing a hoop with a wire element 8 of the fiber-based type such as carbon fibers, glass fibers or other fibers. fibers, since it allows to exert very high tension on the fiber yarn during its winding around the part 3, without risk of damaging it. The machine 1 can, however, also be used for producing a hoop using wire elements 8 of the monofilament wire type, such as steel wire, titanium wire, invar or other suitable materials. The machine 1 can also be used to tension the wire element with a better control of the voltage, lower than in the case of shrinking, for example in the context of a conventional filament winding where the wire element 8 is also of the fiber-based yarn type such as carbon fibers, glass fibers or other fibers, or even in the context of a marouflage of a composite tube where it is necessary to tension a wired element 8 of the plastic tape type for compacting said tube during its molding.

In the context of the application of particular interest to us, namely the hooping or filament winding with a wire element 8 of wire type based on composite fibers, it is possible to provide an impregnation of the wire with a resin (not shown). The wire element 8 may be impregnated with a resin during molding, that is to say after being unwound from the coil 7. The wire element 8 may also be pre-impregnated with a resin, that is to say before it is placed on the machine 1. The wire element 8 could also comprise an already polymerized resin or a thermoplastic resin. This resin can optionally be flexible. The wire element 8 may be impregnated with an excess of resin and then calibrated by one or two successive calibrations passing through two dies. The first die makes it possible to approach the desired fiber content on the wire element and the second die makes it possible to reach the desired final diameter of the wire element. The realization of two successive calibrations makes it possible to preserve the fiber.

In order to achieve such impregnation, the machine 1 also comprises an impregnating system (not shown) that can consist of a resin tank in which the wire element 8 passes after being unrolled from the coil 7 and before it passes through the tensioning system 10, even after its passage. The impregnation can also be done by a different method, for example by depositing a bead of resin directly on the wire element 8 during its winding around the piece 3. The impregnation system may also comprise a roller (not shown) which will be coated with resin by passing through a resin bath, the wire element 8 passing on this roller to be impregnated with the resin. The machine 1 may also comprise a torsion system (not shown) of the wire element 8, arranged upstream of the tensioning system 10, in order to twist said wire element 8 and make it more resistant before it is put into tension. This torsion system may consist of a support on which is mounted the coil and a driving motor in rotation of the support, the speed of rotation of the coil being imposed by the speed of travel of the wire element, the programmable controller managing said speeds. One could also consider twisting the wire element 8 before winding it on the coil 7.

Some parts 3 may have a surface that may damage the wired element 8 under tension during its winding, especially during a shrinking operation. This is the case for example for a magnet rotor with surface imperfections. In this case, it is possible to add a protective film on the surface to be shrunk, for example a fiberglass or carbon fabric, before starting the winding of the wire element 8 under tension on the part 3.

FIGS. 8 and 9 illustrate another alternative embodiment of the tensioning system 10 of the wire element 8. The tensioning system 10 comprises two rollers 11a-11b interconnected by a set of gears 12 having two gears 12a-12b. The first roller 11a is shifted upwards and forwardly relative to the second roller 11b, as illustrated in FIGS. 8 and 9. The rollers 11a-11b are of identical diameters and the gear set 12 ensures rotation of the two rollers lla-l lb in two opposite directions with a transmission ratio equal to one (r = 1). The direction of rotation of the rollers 1 la-1 lb corresponds to the direction of movement of the wire element 8, as illustrated by the arrow 14. The gear set 12 makes it possible to brake only one of the two rollers 1 la-l lb to transmit a torque distributed on each of said rollers l la-l lb. The wire element 8 is wound on the rollers 11a-1b by making a passage as illustrated in FIG. 8, or even several passages as illustrated in FIG. 9, said wire element 8 being in contact with the front part of the first roller 1 la and with the rear portion of the second roller 11b, as illustrated in these Figures 8 and 9, which ensures a total contact angle of 360 ° during a passage. The rollers 11a-1b may include successive grooves (not shown) for shifting the wire element 8, as described above. The support system 2 described above makes it possible to rotate the workpiece 3 along its axis of revolution XI, which ensures the winding of the wire element 8 around said workpiece 3. However, other variants of winding system 100 of the wire element 8 around the piece 3. For example, on the machine 1 illustrated in FIG. 10, the winding system 100 comprises a mandrel 15 for fixedly holding the workpiece 3 and a satellite 16 having a depositing head 17 for holding and guiding the wire element 8 at the time of its winding on the 3. The machine 1 comprises a rotation drive system (not shown) of this satellite 16 around the axis of revolution XI of the part 3, which allows the winding of the wire element 8 around said 3. The machine also comprises a translation system (not shown) of this satellite 16 in the direction of the axis of revolution XI of the part 3, which allows to move the wire element 8 in the direction of this axis of revolution XI during its winding around the piece 3. One could consider a system of translation of the mandrel 15 in the direction of the axis of revolution XI as a variant of the translation system of the satellite 16, to form a system of displacement of the lement wired 8 along the axis XI revolution during its winding around the room 3.

In the examples of tensioning systems 10 described above, the rollers 11a-11g are all of identical diameter and the gear wheels 12a-12g provide a transmission ratio equal to one (r = 1) between them. However, it would be possible to envisage different diameters for the rollers 1a-1lg and to adapt the gear wheels 12a-12g so that the transmission ratios between these gear wheels ensure an identical speed of travel of the element 8 on these rollers 1a. -11 g.

In particular, the diameters of the rollers 11a-11g could be increased progressively to take account of the elongation of the wire member 8 which is energized. In fact, given the elongation of the wire element at the applied voltage level, the speed of travel will be slightly greater after braking than before braking. The speed will gradually increase as braking progresses. It may then be interesting to increase the diameter of the rollers 1 la-1 lg to account for the speed of scrolling that increases. This will make it possible, in the case of a very fragile wire element 8, to reduce the sliding of said wire element 8 on said rollers 1a-11g.

The foregoing detailed description is in no way limiting. On the contrary, it aims to remove any imprecision as to its scope. Thus, many variants may be envisaged within the context of the invention, in particular as regards the design of the tensioning system 10.

Claims

1. Method of shrinking a workpiece (3) by winding a tension element (8) under tension around this workpiece, comprising at least one step of transporting the wire element to the workpiece and a step winding the wire element around said part, characterized in that it comprises a step of tensioning the wire element before winding it around the part, said step being implemented:

by performing at least one passage of the filament element around at least one roller (11, 1 la-11 g) so as to generate an angle of contact of the filament element with the at least one roller, upper or equal to 360 ° (a> 360 °),

and braking the at least one roller so as to brake the wire element (8) and turn it on.

2. Method according to claim 1, wherein the wire element (8) is wound around at least two rollers (1 la-11 g) by making at least one passage.

3. Method according to one of claims 1 or 2, wherein is carried out several passages around the at least one roller (11, 11 a-11 g) by shifting the wire element (8) on said at least one roller during each pass.

4. Method according to one of the preceding claims, wherein the filament element (8) is a fiber-based yl.

5. Method according to claim 4, wherein the wire element (8) is twisted prior to its passage around the at least one roller (11, 1 la-1 lg).

6. Method according to one of claims 4 or 5, wherein said filament element is impregnated with a resin prior to its winding around the workpiece (3).

7. Method according to one of claims 1 to 3, wherein the filament element (8) is a mono-filament film.

8. Machine (1) for shrinking a workpiece (3) by winding a tension element (8) under tension around this workpiece, the machine comprising:

a winding system (2) of the wire element (8) around the part (3), a support system (6) of a coil (7) on which the wire element (8) is wound, said system being configured to allow unwinding of the wire element (8) of the coil (7),

characterized in that said machine (1) comprises a tensioning system (10) of the wire element arranged between the support system (6) and the winding system (2), said tensioning system ( 10) comprising: at least one roller (11, 11 a-11 g) configured so that the filament element makes at least one passage around the at least one roller by generating an angle of contact of said element with said at least one roller, greater than or equal to 360 ° (a> 360 °),

a braking device of the at least one roller so as to brake the wire element (8) and turn it on.

9. Machine (1) according to claim 8, wherein the tensioning system (10) comprises at least two rollers (11 a-11 g) configured to perform at least one passage of the wire element (8).

Machine (1) according to one of claims 8 or 9, wherein the braking device comprises:

gear means (12) configured between the rollers (11 a-11 g) to drive them simultaneously in rotation with the same speed of movement of the filament element

(8);

braking means of one of the rollers.

11. Machine (1) according to one of claims 8 to 10, which comprises a torsion system of the wire element (8) arranged upstream of the tensioning system (10).

12. Machine (1) according to one of claims 8 to 11, which comprises a system for impregnating a resin on the wire element (8) before winding around the piece (3).

13. Machine (1) according to one of claims 8 to 12, which comprises means for measuring the torque exerted on the at least one roller (1 1, 1 1 a-11 g) and / or on the workpiece ( 3) and means for controlling the braking device of the at least one roller configured to adjust said braking as a function of the torques measured on the at least one roller and / or on the part (3).