Installation for the placement of fiber bundles coated with a curable matrix in a room with through channels

Abstract

Installation (100) for placing bundles of fibers (10) coated with a curable matrix in a part (1) having channels (4) each opening through at least two distinct orifices (5, 6) and having at least one curved portion, comprising means (121, 152) for generating a pressure difference between the two orifices (5, 6) of each channel (4), so as to cause the movement of the bundle (10) inside said channel (4), characterized in that it comprises a ogive (20) configured to be fixed to one end of the bundle (10). Figure 3

Description

Title of the invention: Installation for the placement of fiber bundles coated with a curable matrix in a part having open channels. Technical field

[0001] The invention relates to the field of mechanical design of composite material parts. More specifically, it relates to an installation for placing reinforcement fiber bundles inside a body having through channels. It further relates to an installation designed to meet stringent requirements regarding the geometry of the channels, including their length, curvature, and surface finish. Previous techniques

[0002] The reinforcement of mechanical parts, and the design of parts with optimized performance in terms of strength and weight, frequently involves the use of composite materials. By composite materials, we generally mean a fibrous material, usually based on high-tenacity fibers or filaments, which are associated with a hardenable matrix, which can be thermoplastic, i.e., which can soften or even melt beyond a certain temperature, or thermosetting, i.e., which adopts a solid configuration after being exposed to an energy source, for example by cross-linking in the case of resins.

[0003] Various documents have already proposed to produce parts integrating fiber bundles associated with a hardenable matrix, in order to create reinforcement zones arranged in an optimized way inside a larger part.

[0004] By way of example, document EP 3 231 592 describes a technique that consists of creating a body with the dimensions of the final part and generating through channels within it, into which bundles of fibers impregnated with a resin intended for hardening are introduced. More precisely, these fiber bundles are introduced into the channels at the same time as the resin impregnating them is injected into the same channel. The pressure exerted on the resin causes the fiber bundle to advance through friction with the fibers. The bundle thus progresses through the channel to its other end.

[0005] This technique has several drawbacks. The geometry of the channels must be chosen to limit curvatures, and even their length. More specifically, the entrainment of the fibers by the resin flowing in the channel is slowed by friction between the fibers and the inner wall of the channel, which occurs in the areas of curvature. Nevertheless, to ensure an effect For sufficient resin entrainment, the fiber bundle must be large enough to occupy a significant portion of the canal cross-section. However, this increases friction, which, as we have seen, is detrimental to the bundle's proper advancement. Reducing the fiber bundle size limits this friction but necessitates a larger resin flow, resulting in losses or, at the very least, the need to manage excess resin exiting the canal. Furthermore, the fiber bundle's progression within the canal can be disrupted by surface irregularities in the canal wall, potentially causing the bundle's tip to abut against the walls, resulting in a blockage of part or even all of the fiber bundle.Furthermore, this technique requires applying very high pressure to ensure beam progression, with the associated drawbacks related to the size and power consumption of the equipment.

[0006] A manufacturing process for parts incorporating composite reinforcements, which uses perfectly straight channels, is known from document WO 92 / 16347. In this case, a fiber bundle is introduced into the straight tubular channel, its inlet end attached to a ogive whose shape complements the channel. The pressure exerted on the resin impregnating the fiber bundle causes this ogive to move and the fiber bundle to be drawn into the channel. However, this solution has the drawback of only working for perfectly straight channels, which is incompatible with the objective of increasing mechanical performance, which most often requires that the reinforcing elements have a curved geometry within the part they reinforce. Description of the invention

[0007] The objective of the invention is therefore to propose a solution which overcomes the disadvantages of the prior art, and which thus allows the placement of reinforcement fiber bundles in channels of a wide variety of lengths and geometries.

[0008] The invention therefore relates to an installation for placing bundles of sand-cured matrix-coated fibers in a part having channels opening through at least two distinct orifices and having at least one curved portion. This installation includes means for generating a pressure difference between the two orifices of each channel, so as to cause the bundle to move within the channel.

[0009] According to the invention, this installation is characterized in that it comprises an ogive configured to be attached to one end of the fiber bundle.

[0010] In other words, the invention consists of equipping the fiber bundle with a component having dimensions similar to the cross-section of the channel, such that the pressure difference between the upstream and downstream sides of this component causes its displacement and the entrainment of the fiber bundle. The upstream or rear side of the ogive is understood to be the side of the ogive facing the channel's inlet orifice and opposite the fiber bundle, as opposed to the upstream or front side of the ogive, which is the side facing the channel's outlet orifice and the direction of bundle progression. In other words, the bundle's progression within the channel, particularly in curved sections, is ensured by the traction exerted by this ogive, which prevents, or at least limits, the end of the bundle from abutting against one of the channel walls.

[0011] The pressure difference that causes the ogive to move can be generated in various ways. For example, a low-pressure area can be created near the outlet end of the channel, causing the ogive to be drawn in, with its rear end (in the direction of beam progression) subjected to atmospheric pressure. In this case, it is preferable for the ogive to be in contact or near-contact with the channel wall to limit the suction of the hardenable matrix by the low pressure, through any gap that might exist between the ogive and the channel.

[0012] It is also possible to cause the ogive to move by applying overpressure at the channel inlet. To do this, the hardenable matrix for impregnating the beam is delivered under pressure, so that it exerts a thrust on the rear face of the ogive, the front face of which is exposed to less pressure. Obviously, a combination of upstream overpressure and downstream underpressure can also be implemented.

[0013] Different variants can be developed with regard to the shape, geometry and construction of the ogive.

[0014] In a first embodiment, the ogive can be overmolded onto the end of the bundle. In other words, the ogive is formed by a part generated by the solidification of a material deposited on the end of the fiber bundle. In this way, and depending on the choice of materials, this material can penetrate the core of the fiber bundle, thus ensuring very effective bonding, useful for preventing the ogive from unexpectedly separating from the bundle when significant forces are applied to it.

[0015] In other embodiments, the ogive can be secured by appropriate means, such as, for example, by crimping or, more generally, by a device ensuring the clamping of the bundle, attached to the ogive. In this case, the retention of the bundle can be more effective and adapted to certain types of fibers. It is also possible that the portion of the bundle attached to the ogive has a given cross-section and connects to a portion of the bundle with a different, for example, larger, cross-section. After a few centimeters or tens of centimeters, the fiber is moved to facilitate the movement of the ogive and, in particular, its orientation within the channel. This allows the fiber to fill more space in the cavity by conforming to its cross-section after the ogive has passed, thus improving mechanical properties while reducing the amount of curable matrix used.

[0016] Depending on the application, it may be useful for the ogive to have a cross-section, measured in a plane perpendicular to the beam direction, that fits within the cross-section of the channel. In other words, the outer contour of the ogive is very slightly smaller than the cross-section of the channel, so that a slight clearance exists between the ogive and the channel, facilitating the movement of the ogive.

[0017] Conversely, it is also possible for the ogive to have a peripheral zone that is deformable, so as to conform to the shape of the channel as it travels through it. In other words, in this case, the outer wall of the ogive rubs against the wall of the channel, thus ensuring a good seal, and preventing or at least limiting resin leakage resulting from the pressure difference between the upstream and downstream sides of the ogive.

[0018] This configuration is particularly advantageous in the case where the channel wall is not perfectly regular, which may be the case in particular when the channel has been generated by an additive deposition operation or 3D printing.

[0019] The deformable material of the ogive may be present only in the peripheral area of ​​the ogive, while the center of the ogive, in contact with the fiber bundle, has greater rigidity.

[0020] In a particular embodiment, the ogive may comprise several regions having maximum value cross-sections arranged at different levels along a direction parallel to the fiber bundles. In other words, the ogive has successive bulges, which constitute so many zones coming into contact with the channel wall, thus increasing the seal between the upstream and downstream sides of the ogive.

[0021] In a particular embodiment, the ogive can be composed of several distinct elements, attached to the fiber bundles at different levels along a direction parallel to the bundles. In other words, the end of the fiber bundle comprises a train of several elementary ogives, each providing a fraction of the sealing between the upstream and downstream ends of the overall ogive. This offers the additional advantage of taking advantage of the flexibility of the fibers so that the different elements shift relative to each other as they pass through the curved sections of the channel.

[0022] In other words, this configuration ensures the proper progression of the fiber bundle in a highly curved channel, while also ensuring good force training. In other words, this configuration gives the ogive a deformable character that allows it to adapt to a significant curvature of the channel.

[0023] Among the geometries that have proven satisfactory, one can notably mention those in which the ogive has at least one annular portion curved backward in the direction of beam progression. In other words, the ogive has a peripheral lip, oriented upstream from the center of the ogive, so as to be pressed against the channel wall when the upstream pressure becomes greater than the downstream pressure of the ogive. Thus, this geometry offers good pressure resistance while ensuring a high level of sealing.

[0024] In a particular embodiment, these annular portions also have radial cutouts, which allow for independent deformation of the regions located between two cutouts. In other words, the annular lip has sectors that are relatively independent of each other, making it possible to follow an irregular configuration of the canal wall. Naturally, the number and dimensions of these cutouts must be adapted according to the overall geometry of the ogive and the pressures applied, to ensure optimal beam progression within the canal.

[0025] Advantageously, in practice, the surface of the ogive intended to come into contact with the channel may have a surface coating made of a material with a coefficient of friction lower than that of the portion in contact with the fiber bundle. In other words, the progression of the ogive, and therefore of the bundle, can be facilitated by arrangements that limit the friction of the ogive on the channel wall. Brief description of the figures

[0026] The manner of implementing the invention, as well as the resulting advantages, will become clear from the description of the embodiments that follow, with support from the accompanying figures in which:

[0027] [Fig-1] is a rough perspective view of a part intended to receive a fiber bundle during processing by the installation according to the invention.

[0028] [Fig.2] is a view analogous to [Fig. 1], in which the part has received the beam of fibers.

[0029] [Fig.3] is a simplified schematic view of one embodiment of the installation in accordance with the invention.

[0030] [Fig.4] is a cross-sectional view of a mold allowing the production of a first variant of the ogive according to invention.

[0031] [Fig. 5] a cross-sectional view showing the production of the ogive with the mold of the [Fig.4],

[0032] [Fig.6] is a cross-sectional view showing a second variant of the ogive, mounted on a bundle of fibers.

[0033] [Fig.7] is a cross-sectional view of a third embodiment of the ogive, showing on the left side the ogive in a configuration before introduction into the channel, and on the right side the ogive in the configuration it takes after introduction into the channel.

[0034] [Fig.8] is a simplified cross-sectional view showing a fourth embodiment of the ogive formed from a train of individual ogives.

[0035] [Fig.9] is a summary perspective view of a fifth embodiment variant of the ogive.

[0036] [Fig. 10] is a summary perspective view of a sixth embodiment of the ogive, mounted on a bundle of fibers.

[0037] [Fig. 11] is a simplified side view of part of the ogive of [Fig. 10].

[0038] [Fig. 12] is a side view of a seventh variant embodiment of the ogive.

[0039] [Fig. 13] is a side view of an eighth variant embodiment of the ogive.

[0040] Of course, the examples given in the figures are for illustrative purposes only, and the Dimensions and proportions shown may differ from reality, and may have been exaggerated to facilitate understanding of the invention. Ways to implement the invention

[0041] As already mentioned, the invention relates to an installation for manufacturing mechanical parts including reinforcing elements in the form of a bundle of fibers impregnated with a hardening material that gives the part high mechanical properties. This material can be a thermoplastic matrix or a thermosetting resin, or any other material that is in a liquid state when introduced into the part and subsequently hardens.

[0042] Obviously, the shape, geometry, and dimensions of these parts can vary greatly depending on the desired application. Such a part can be manufactured in different ways, particularly through additive manufacturing processes, commonly referred to as "3D printing." With these processes, the manufactured parts are created by the successive deposition of layers, each layer consisting of an elementary bead deposited along a path that defines the shape of the part to be produced. This construction method makes it possible to create cavities or any kind of recess within the part, notably to generate through channels.

[0043] An example of such a part is illustrated in [Fig. 1]. Thus, this part 1, which can serve, for example, as a connecting piece, has two through recesses 2, 3 that serve a functional purpose. This part 1 has a channel 4 that runs inside the part 1, passing around the two recesses 2, 3. This channel has an inlet orifice 5 and an outlet orifice 6 in which, as illustrated in [Fig. 2], can be introduces a bundle of fibers 10, the end of which is equipped with a ogive 20 which will be described in detail later.

[0044] An installation according to the invention is schematically represented in [Fig. 3], in which part 1 is shown, the channel 4 of which has its inlet 5 connected to equipment for introducing the fiber bundle 10 into part 1. Generally, this equipment 120 comprises a chamber 122 in which the fiber bundles intended for introduction into part 1 are stored. This chamber 122 is pressurized by a compressor 121 and also includes a bath 125 in which the fiber bundle 10 is impregnated with a resin. The installation also includes a conduit 128 through which the impregnated bundle 10 travels. Depending on the application, the matrix can be formulated with components necessary for its stiffening, which are determined according to the desired properties.This may include, in particular, a hardener which, after mixing with the resin, allows the latter to cross-link when it is inside part 1 and the joint is activated, for example by exposure to a heat source. The formulation can be prepared within the installation or beforehand.

[0045] Valves and pneumatic or hydraulic components necessary for the proper functioning of the installation may be arranged in appropriate locations, but have not been shown, for the sake of simplicity.

[0046] The conduit 128 extends into a mouthpiece 138 which can be applied to the inlet orifice 5 of the channel 4 of the part 1. Of course, provisions are made to ensure a seal between the injection installation 120 and the part 1, and thus prevent any leakage of resin during the progression of the fiber bundle 4 inside the part 1. This may in particular be a fitting present on the part 1, onto which the mouthpiece 138 is inserted.

[0047] In the illustrated form, the installation 100 also includes equipment connected to the outlet port 6 of the channel 4. This equipment 155 mainly includes a vacuum pump 152, connected by a suitable pipe 154 to the outlet port 6. Other complementary equipment can be added, in particular to recover the resin which will have been sucked up by the pump 152.

[0048] As already mentioned, the progression of the free bundle inside the part 1 is caused by the pressure difference between the inlet orifice 5 and the outlet orifice 6 of the channel 4. This pressure difference can be generated either by the overpressure inside the inlet installation 120, which causes the expulsion of the resin and the fiber bundle, or by the suction generated by the vacuum pump 152 of the outlet equipment, or by a combination of overpressure and vacuum as illustrated in [Fig.3].

[0049] For this pressure difference to be effective, the end of the fiber bundle must be drawn into the channel 4 by the characteristic ogive.

[0050] Several geometries and ogive constructions can be used depending on the dimensions and shapes of the channel to be filled, as well as its surface condition.

[0051] In a first embodiment illustrated in Figures 4 and 5, the ogive 200 is produced from a mold 201 having an overall shape of revolution. More precisely, this mold 201 has areas of larger cross-section 203, and areas of smaller cross-section 204 which follow one another, to form an envelope having a succession of bulges arranged according to the direction of progression of the beam F.

[0052] As illustrated in [Fig. 5], manufacturing the ogive requires introducing the fiber bundle 4 into the mold 201, advantageously by passing the bundle 4 through the hole 205, and then filling the mold with a material 202, which fills the mold's volume. In this way, after the material 202 has solidified, the ogive 200 is created with regions of larger cross-section 206 separated by regions of smaller cross-section 207.

[0053] In practice, the mold 201 is made of a material that can be easily peeled off to release the ogive 200 it contains.

[0054] The material introduced into the mold 201 is in a liquid state, so as to impregnate the fiber bundle and thus ensure the strongest possible bond between the ogive and the bundle 4. Advantageous materials include, for example, silicones, elastomers, and in particular rubbers and polyurethanes.

[0055] In general, the material used to make the ogive obviously has chemical resistance properties to the impregnation resin, but also mechanical bending properties which allow it to deform when the channel has a certain curvature.

[0056] Similarly, the shape and dimensions of the ogive area facing the inner wall of the channel can be adapted, on the one hand, to the general shape of the channel, and on the other hand, to the viscosity of the resin impregnating the fibers. Thus, in the shape illustrated in Figures 4 and 5, the ogive has a shape such that the gap between the most swollen portions 206 and the inner wall of the channel is minimal, so as to increase pressure losses along the resin's path and to prevent, as much as possible, the resin from spreading faster than the ogive moves.

[0057] In an alternative form illustrated in [Fig. 6], the ogive 300 has a particular shape, composed of three cylindrical sections 302, 304, 306 with a diameter reduced compared to that of the channel. Between each cylindrical section, there is a swollen portion or dome 305, 307, 309 which extends over a larger diameter, which may be on the order of, or even slightly larger than, that of the channel. Thus, the perimeter The exterior 323 of each of the domes can come into contact with the wall when these wings deform during insertion into the channel. The shape of the domes 305, 307, 309 is such that the upstream surface, that is to say the one which is behind in the direction of progression F of the beam, is oriented upstream away from the beam 4. In this way, when the resin pushes the ogive, 100, this surface 320 straightens, approaching a plane perpendicular to the beam 4, so as to press the circumference 323 of the dome against the wall of the channel, thus increasing the seal with respect to the resin, between the upstream and downstream sides of the ogive. Additionally, the front face 321 of each dome, oriented downstream in the direction of beam progression, is configured to allow upstream deformation of the dome to be easier than downstream deformation of the dome.

[0058] Of course, the number of domes and the dimensions of the cylindrical portions are determined according to the expected tensile forces, themselves a function of the length of the channel, the size of the beam to be put in place, the surface condition of the internal wall of the channel as well as the level of pressure difference applied.

[0059] In an alternative form illustrated in [Fig. 7], the ogive can be composed by assembling several parts made of different materials. Thus, the central portion 410 of the ogive 400 constitutes the part that ensures the attachment of the ogive to the fiber bundle 4. This central portion 410 receives at its downstream end a part 420 forming a frustoconical section whose bottom 421 is integral with the central portion 410 of the ogive 400. The frustoconical wall 425 has a deformation capacity relative to its junction 428 with the bottom 421, so that this frustoconical section can deform, approaching the cylindrical configuration illustrated in the right-hand part of [Fig. 7], when the ogive comes into contact with the inner wall 12 of the channel 10.Additionally, the outer face of the truncated conical wall 435, 425 is equipped with lips 426, or more generally, protrusions with a low coefficient of friction, so as to limit friction with the inner wall of the channel, while ensuring a good seal between the upstream and downstream sides of the ogive. This configuration has the particular advantage of maintaining this level of sealing despite irregularities in the channel's geometry. These irregularities can be observed, in particular, when the part to be reinforced has a geometry that is not perfectly cylindrical and contains potential constrictions.

[0060] In this case, the deformation of the truncated conical portion of the ogive ensures permanent contact of the apexes 436 of the lips with the internal wall of the channel.

[0061] In another embodiment illustrated in [Fig. 8], the ogive can be composed of several elementary ogives assembled on the fiber bundle 4. In the illustrated form, the three elementary ogives 501, 502, 503 have ellipsoidal shapes, but other shapes can be adopted depending on the constraints of the channel, the beam, and the impregnation resin. The dimensions of the individual ogives are determined to allow a slight clearance with the inner wall of the channel, permitting a small leakage of resin to fill the volumes 500 and 509 separating the individual ogives, thus distributing the pressure losses at each individual ogive. This configuration has the advantage of facilitating the deformation of the overall ogive 500 and, thanks to the deformability of the beam 4, allowing it to adapt to high curvatures of the channel 4. Naturally, the number of individual ogives and the shape of each can be adapted according to the application.

[0062] In the embodiment illustrated in [Fig. 9], the ogive 600 is in the form of two domes 601 and 611, connected by a central cylindrical portion 620. Each of these domes 601, 611 has a geometry similar to the domes illustrated in [Fig. 6], with the addition of radial cutouts 603, 613 which define petals 604, 614 connected to a central circular area 605, 615 which is itself connected to the cylindrical shafts 620. In this way, each of the petals 604, 614 has a certain flexibility, which allows it to move independently of the neighboring petals. Thus, petals 608, 618, and 619, illustrated in [Fig. 9], are shown in a position where they are slightly more inclined upstream than the other two petals of the domes. This corresponds to the deformations resulting from encountering a localized irregularity on the internal surface of the channel.Thus, in this case, only the petal(s) opposite this irregularity are deformed, leaving the other petals in their normal configuration in which they come into contact with the inner wall of the channel. The number of cutouts 603, 613 as well as their dimensions are determined to maintain a satisfactory level of sealing compatible with the progression of the ogive.

[0063] Another variant is illustrated in [Fig. 10] in which the ogive 700 is composed of a train of elementary ogives 701, 702. Each of these elementary ogives 701, 702 has a shape extending radically from the fiber bundle 4 towards the channel wall, adopting a geometry of corrugated or "sine" washers. More precisely, this profile is such that certain points 704 on the periphery of the elementary ogive 701 are located at a higher level than certain other points 705, and this alternately. In this way, each of these elementary ogives has the capacity to deform locally in the event of encountering an irregularity in the surface of the inner wall of the channel, limiting this deformation to avoid generating excessive leaks on the remaining elementary ogives.The geometry, namely the number of undulations and their amplitude, is determined according to the materials used and the operating conditions. Of course, the two elementary ogives 701, 702 are illustrated in figures 10 and 11. can be connected by a common portion of the ogive forming a cylindrical shaft like that of [Fig.9].

[0064] In the variant illustrated in [Fig. 12], the ogive consists of a swollen portion 808 formed at the end of the bundle 804. More precisely, the bundle 804 is made by assembling several wires 805, 806 that are braided together. At the end 809 of the bundle, the tightness of the braiding is partially loosened, so that the wires 805, 806 move apart to widen the bundle. The end 809 is embedded in a droplet 810 that can be shaped to conform to the shape of the channel.

[0065] The ogive 900 illustrated in [Fig. 13] is remarkable in that it comprises a special region 901, equipped with a helical or screw-shaped wall 902. This wall 902 allows the ogive to rotate around its axis, i.e., in the direction of the fiber bundle, as the ogive progresses inside the channel. This rotation causes the fiber bundle 904 to twist as it advances through the channel. This twist tightens the fiber by twisting it and improves its alignment. This has the advantage of reducing the drag of the bundle in the channel and facilitating the addition of other fibers as the bundle advances. The dimensions of this wall, namely the width, pitch, and length, are determined according to the viscosity of the matrix and the diameter of the bundle to ensure optimal progression.

[0066] These configurations described above are particularly well-suited to the channel shapes generated in parts produced by additive manufacturing or 3D printing, where the transitions between two successive deposited layers create irregularities that become increasingly pronounced as the channel direction deviates from the perpendicular to the plane between layers. The various configurations can be adapted and combined according to the application.

[0067] It follows from the foregoing that the installation according to the invention makes it possible to ensure the placement of the reinforcing fiber bundles inside the parts while being particularly tolerant of the surface condition of the channel walls, as well as their curvature. The use of the characteristic ogives makes it possible to reduce the cross-section of the channels, for an equivalent quantity of fiber, thus requiring less hardenable matrix and simplifying the parts to be manufactured. At the same time, the pressure level required for the propagation of the bundles is lower than that observed in the prior art, consequently simplifying the characteristic installation.

Claims

Demands

1. Installation (100) for the placement of bundles of fibers (10) coated with a hardenable matrix in a part (1) having channels (4) each opening through at least two distinct orifices (5,6) and having at least one curved portion, comprising means (121,152) for generating a pressure difference between the two orifices (5,6) of each channel (4), so as to cause the movement of the bundle (10) inside said channel (4) characterized in that it comprises a ogive (20) configured to be attached to one end of the bundle (10).

2. Installation according to claim 1, characterized in that the ogive (200) is overmolded on the end of the beam (10).

3. Installation according to claim 1, characterized in that the ogive (200) has a section, measured in a plane perpendicular to the direction of the beam, which fits within the section of the channel (4).

4. Installation according to claim 1, characterized in that the ogive (300; 400) has a peripheral zone (305,307,309; 425,435) which is deformable, so as to conform to the shape of the channel (4) when it travels through it.

5. Installation according to claim 1, characterized in that the ogive (200;300;400;600)) comprises several regions (206;305,307,309;425,436;601,611) having sections of maximum values, arranged at different levels along a direction parallel to the beam (10).

6. Installation according to claim 5, characterized in that the ogive (500) is composed of several distinct elements (501,502,503) attached to the beam (10) at different levels in a direction parallel to the beam.

7. Installation according to claim 1, characterized in that the ogive (300;600) comprises at least one annular portion (305,307,309;601,611) curved backwards in the direction of progression of the beam.

8. Installation according to claim 7, characterized in that the annular portion (601,611) has radial cutouts (603;613), allowing independent deformations of the regions (604;614) located between two cutouts.

9. Installation according to claim 1, characterized in that the surface (425,426) of the ogive intended to come into contact with the channel has a surface coating (426,436) made of a material having a coefficient of friction lower than that of the portion (410) in contact with the fiber bundle.

Images