Removable fiber-wound mandrel assembly having axially slidable inner and outer mandrel portions provided with axially oriented opposing guide surfaces and complementary coupling portions

Abstract

A removable fiber-wound mandrel assembly (1) is used to wind fibers around the removable fiber-wound mandrel assembly during the production of hollow fiber-wound composite material parts (7). The removable fiber-wound mandrel assembly includes: at least two elongated outer mandrel portions (2) that together define an elongated central insertion space (3); and an elongated inner mandrel portion (11) having a central axis (X) extending in an axial direction; the outer mandrel portions (2) are laterally displaceable between an expanded winding state and a contracted removal state; the mandrel portions include complementary coupling portions (8) configured to restrict the outer mandrel portions (2) in a laterally outward direction in the expanded winding state; an inner guide surface (4) of the outer mandrel portion (2), an outer guide surface (12) of the inner mandrel portion (11) opposite to the inner guide surface (4), and the complementary coupling portions (8) all extend parallel to the central axis (X), and the inner mandrel portion (11) has a constant cross section.

Description

Technical Field

[0001] This invention relates to a removable fiber-wound mandrel assembly for winding fibers around hollow fiber-wound composite parts (particularly hollow fiber-wound composite bicycle parts) during production. The invention also relates to a method for producing hollow fiber-wound composite parts around such a removable fiber-wound mandrel assembly. Background Technology

[0002] Fiber winding is a manufacturing technique involving winding fibers under tension onto a rotating fiber winding mandrel. The mandrel rotates around itself while transfer eyelets on a carriage pass horizontally along the axis of the rotating mandrel, thereby arranging the fibers on the mandrel in a desired pattern or angle. The angle of fiber winding affects the performance of the final product. Larger angles provide circumferential strength, while smaller angle patterns provide greater longitudinal / axial tensile strength. The most commonly used fibers are glass or carbon fibers impregnated with resin before, during, or after winding around the mandrel. For example, the fibers may pass through a resin bath just before winding around the mandrel. Instead of impregnating the fibers with resin before winding (wet winding), it is also known to utilize pre-impregnated fibers (dry winding) or impregnate them after winding. Wet winding has the advantage of being able to use low-cost materials with long shelf life and low viscosity. Pre-impregnation systems can produce parts with more consistent resin content and can be wound more quickly.

[0003] Once the mandrel is completely covered to the desired thickness, the resin cures. Depending on the resin and its curing properties, the hollow fiber wound composite part, typically still surrounding the mandrel, is autoclaved or heated in an oven or rotated under a radiant heater until the part is fully cured. The mandrel can then be removed, for example, by removing it from the hollow fiber wound composite part. Alternatively, the mandrel can be removed before curing begins.

[0004] Currently, hollow fiber-wound composite components produced using this fiber winding process include hollow bicycle components such as forks and rims made from fiber-wound composites. Specifically, carbon fibers cured with resin are then used. These hollow fiber-wound composite bicycle components are lightweight, strong, and durable, making them ideal for high-performance bicycles.

[0005] One challenge during this production process is removing the mandrel from the hollow shape of the tightly wound fibers, especially if it is expected to be completed before curing. The mandrel may be tightly wound with fibers, making it difficult to access and remove it without damaging the hollow shape of the tightly wound fibers. If not removed carefully, the removal of the mandrel can cause cracks, fragmentation, or deformation in the hollow fiber wound composite component.

[0006] EP 0206268 A2 discloses a multi-part fiber winding mandrel for winding resin-saturated fibers. The fiber winding mandrel comprises an elongated central core having four elongated outer mandrel portions positioned around it, which together define a winding surface. Each of the four outer mandrel portions is formed by two pairs of diametrically opposed outer mandrel portions. The central core is axially movable within a central space left inside each of the outer mandrel portions. Two sets of diametrically opposed and spaced-apart T-shaped sliders are disposed on the opposing surfaces of the central core as convex connecting portions. These T-shaped sliders are slidably fitted into corresponding sets of radially opposed and spaced-apart T-shaped grooves, which serve as concave connecting portions on the opposing surfaces of the outer mandrel portions. These T-shaped grooves extend inwardly at an angle relative to the axial direction.

[0007] Due to the wedge-shaped effect caused by the inward tapering of the paired, radially opposite, and spaced connecting portions, the axial movement of the central core should simultaneously begin by gradually pulling the first pair of radially opposite outer mandrel portions radially inward toward each other, followed by gradually pulling the second pair of radially opposite outer mandrel portions radially inward toward each other. This reduces the external dimensions formed by the outer mandrel portions. This reduction makes it possible to demold the hollow fiber wound composite component even after the resin has solidified, without disassembling the entire wound fiber mandrel. Special pulling devices for the hollow fiber wound composite component produced by forcibly pulling the mandrel are not necessary.

[0008] However, a drawback is that the functionality of this known multi-part fiber-wound mandrel needs improvement. High precision is required to align the outer mandrel portion with its spaced-apart angled T-grooves and the central mandrel with its spaced-apart T-sliders, and to maintain this alignment during the axial inward or outward movement of the central mandrel. This is crucial for ensuring the intended gradual inward and outward movement of the outer mandrel portion. Any misalignment or dimensional deviation can damage the fragile, tightly fitted connection.

[0009] Furthermore, the central core and outer mandrel require special machining of their cross-sectional shapes, making their manufacturing complex and expensive.

[0010] Another drawback is that the outward-extending, spaced-out T-shaped sliders are fragile and can be easily damaged during handling.

[0011] It is also possible that these T-shaped sliders will get stuck in the T-shaped grooves during the axial movement of the central core. If this blockage occurs, it will not only cause delays on the work floor, but will also make demolding after winding more difficult, and may lead to damage to the produced hollow fiber wound composite parts, because it may then be impossible to reduce the outer mandrel portion to its target smaller cross-sectional size.

[0012] Another drawback is that the sliding of the blocks within the grooves makes them prone to mechanical wear during frequent use. Therefore, these components may require frequent maintenance or even replacement, causing production downtime and increasing operating costs. Summary of the Invention

[0013] The object of this invention is to at least partially overcome these disadvantages or to provide a usable alternative. Specifically, the invention aims to provide a user-friendly and reliable removable fiber-wound mandrel assembly that is error-proof during use and capable of delivering a constant mass of hollow fiber-wound composite parts, particularly for hollow fiber-wound composite parts in the bicycle industry.

[0014] According to the present invention, this objective is achieved by a removable fiber-wound mandrel assembly as claimed in claim 1, the removable fiber-wound mandrel assembly being used to wind fibers around the removable fiber-wound mandrel assembly during the production of a hollow fiber-wound composite material part, specifically a carbon fiber reinforced bicycle part. The removable fiber-wound mandrel assembly comprises: • At least two elongated outer core sections together define the elongated central insertion space; and • The elongated inner mandrel portion has a central axis extending in the axial direction and a lateral direction perpendicular to that axial direction. The outer mandrel portion can shift laterally between an expanding wound state and a contracted removal state. The outer mandrel portion and / or the inner mandrel portion are provided with complementary connecting parts, which are configured to restrict the outer mandrel portion in a laterally outward direction when in an expanded wound state. The outer mandrel portion, in its expanded wound state, defines an outer winding surface. This outer winding surface is used to wind fibers around the outer winding surface during the production of the hollow fiber wound composite component. In the retracted removal state, the outer mandrel portion defines a reduced outer winding surface for removing the mandrel portion from the hollow fiber wound composite component in the axial direction.

[0015] According to the present invention, the inner guide surface of the outer mandrel portion that defines the central insertion space, the outer guide surface of the inner mandrel portion that is positioned opposite to the inner guide surface, and the complementary connecting portion all extend parallel to the central axis. The inner mandrel portion has a constant cross-section, configured such that when the outer mandrel portion is in its expanded, wound state, it engages with the inner mandrel portion via the outer guide surface of the inner mandrel portion in a sliding manner along the inner guide surface that defines the center insertion space. The inner mandrel portion can be removed from the central insertion space, and the outer guide surface of the inner mandrel portion slides axially along the inner guide surface of the outer mandrel portion. This allows the outer mandrel portion to shift towards a retracted removal state in the lateral inward direction after the inner mandrel portion has been removed from the central insertion space, thereby reducing the central insertion space.

[0016] In the expanded, wound state, the inner mandrel portion is located within the central insertion space defined by the outer mandrel portion. Together, the outer mandrel portions form a shape closure around the inner mandrel portion, while the connecting portion restricts further lateral outward movement of the outer mandrel portions. Here, shape closure means that the arrangement of the outer mandrel portions and the shape of their inner guide surfaces prevent any relative movement between the inner and outer mandrel portions without relying on additional forces such as pulling, pushing, or friction.

[0017] After the winding process around the fiber-wound mandrel has been completed, the multi-part mandrel construction of the present invention allows the mandrel portions to be removed from the hollow fiber-wound composite component in a specific sequence and manner. During this demolding, the inner mandrel portion can first be removed from the central insertion space by smoothly sliding its outer guide surface along the elongated parallel axial direction.

[0018] Therefore, after the inner mandrel portion has been completely pulled out of the center insertion space, the free center insertion space allows the outer mandrel portion to move laterally inward easily and quickly. Due to the initial tight winding of the fibers around the outer winding surface, this inward movement of the outer mandrel portion from its expanded winding state to its contracted removal state can begin well automatically, but can be assisted manually or mechanically.

[0019] The lateral inward movement of the outer mandrel portion toward the center insertion space immediately relieves the initial tight winding tension on it and reduces the contact between the outer mandrel portion and the inner wall of the hollow fiber wound composite component.

[0020] Hollow fiber wound composite parts can be arranged at intervals around a shrinking wound surface. This helps reduce friction between the inner wall of the hollow fiber wound composite part and the shrinking wound surface, which is then defined by outer mandrel portions in their shrinking, removed state during demolding. The outer mandrel portions can then be easily, quickly, and carefully pulled out of the hollow fiber wound composite part in the axial direction. This helps ensure the integrity of newly produced hollow fiber wound composite parts.

[0021] Therefore, the demolding / removal process can be truly systematic and controllable. During the removal of the inner mandrel portion from the central insertion space, the parallel inner and outer guide surfaces slide along each other to allow the inner mandrel portion to be precisely and controllably removed from the outer mandrel portion. This completely prevents any potential jamming between the inner and / or outer mandrel portions.

[0022] Advantageously, the anticipated first lateral inward movement of the outer mandrel portion before pulling it axially minimizes disturbance to the hollow fiber wound composite component. Removal of the outer mandrel portion: Instead of sliding it along the fragile inner wall of the brittle wound fiber with high friction, it is performed by first moving the outer mandrel portion vertically inward a certain distance from the fragile inner wall of the brittle wound fiber, and then pulling it out axially without contacting or barely contacting the fragile inner wall of the brittle wound fiber. This minimizes the risk of damaging or impairing the final product at the end of the fiber winding process, resulting in a higher level of product quality and consistency.

[0023] Therefore, due to this multi-part mandrel construction, after the winding process is completed, the outer cross-sectional dimensions of the outer mandrel portion can be gradually and smoothly reduced without the need to use a certain type of tilting system.

[0024] This invention provides a user-friendly and reliable winding mandrel assembly, which enables the production of consistently high-quality hollow fiber wound composite parts. Advantageously, the various mandrel portions of the mandrel assembly can be easily and quickly assembled together without requiring high-precision alignment. The inner mandrel portion can be simply and quickly pulled out of the central insertion space defined by the outer mandrel portion in one go. There is no risk of jamming or damage because all critical guide surfaces and connections are axially oriented and do not require simultaneous movement of the outer mandrel portion in the lateral inward direction.

[0025] Furthermore, advantageously, the inner mandrel portion is now expected to have a constant cross-sectional shape, making manufacturing easy and economical, for example, by extrusion. Another important advantage of the invention is that the same central core (e.g., a robust and rigid metal rod) can be used as the inner mandrel portion. This same inner mandrel portion can then be used in combination with all sorts of different mandrel portions assembled around it. These outer mandrel portions can have a variety of different lengths and different shapes of outer winding surfaces.

[0026] Similarly, in the expanded, wound state, the outer mandrel portions can together define a constant cross-section for the elongated central insertion space. This makes their inner guiding surfaces economical and easy to manufacture, for example, by molding or 3D printing.

[0027] The primary function of the connecting parts is to block the outer mandrel parts in a laterally outward direction after the inner mandrel parts have been inserted into the central insertion space, while they are in their expanded, wound state. They do not necessarily cause any combination of axial and lateral inward / outward movement.

[0028] Another advantage of parallel guide surfaces is that they help reduce wear and tear on the mandrel sections by preventing any potential jamming or interference, thus extending their lifespan. During insertion and withdrawal of the inner mandrel section, the opposing inner and outer guide surfaces slide against each other, preventing mechanical wear during use. Therefore, the mandrel sections require almost no maintenance or replacement, optimizing production and reducing operating costs.

[0029] In a preferred embodiment, adjacent outer mandrel portions may include elongated opposing abutment surfaces located therebetween, the opposing abutment surfaces also extending parallel to the central axis, wherein these opposing abutment surfaces are configured to be spaced apart from each other in the expanded winding state, and wherein the opposing abutment surfaces are configured to abut against each other in the contracted removal state. After the inner mandrel portions have been completely removed from the central insertion space, the outer mandrel portions may move laterally inward while the spacing between the opposing abutment surfaces decreases. During the lateral inward movement of the outer mandrel portions, the opposing abutment surfaces of the outer mandrel portions do not need to slide along each other simultaneously. Therefore, there is no friction between the opposing abutment surfaces, which allows the outer mandrel portions to move smoothly laterally inward toward each other, and thus minimizes the twisting of the newly wound fibers forming the hollow fiber wound composite component together.

[0030] It is important to note that as long as the outer mandrel portion remains in its expanded, wound state, the spacing between the relatively abutting surfaces also exists as a spacing at the position of the wound surfaces. Therefore, these spacings can be used to locally cut the outer ends of newly manufactured hollow fiber wound composite parts, axially through the wound fibers. These axially cut outer ends of the hollow fiber wound composite parts can then be used to connect them to each other, for example, when they are arranged at an angle to each other, such as in bicycle frames with their triangularly oriented seat tubes, rear forks, and downtubes. For this purpose, different seat tubes, lower and upper hollow fiber wound composite tube components can then be produced, their outer ends cut before removing the inner mandrel portion, and then the axially cut outer ends can be connected to each other after demolding.

[0031] In a further preferred embodiment, the complementary coupling may be disposed between the opposing abutting surfaces of adjacent outer mandrel portions. This allows for the absence of a coupling between the outer and inner mandrel portions. An additional advantage is the complete prevention of blockage between the complementary couplings themselves during the step of removing the inner mandrel portion. This makes the inner mandrel portion almost effortlessly removed from between the outer mandrel portions.

[0032] Another advantage of not having a connecting portion between the inner and outer guide surfaces of the outer and inner mandrel portions is that conventional elongated shapes can be used for the inner mandrel portion. For example, a large bar or rod.

[0033] Preferably, the inner mandrel portion may have a flat outer guide surface, specifically, the outer guide surface together forming a square constant cross-section for the inner mandrel portion. Such bars with angled cross-sections are preferred because they automatically provide a form fit to force the outer mandrel portion and the assembled inner mandrel portion to rotate together along the central axis in an expanded, wound state.

[0034] Then, preferably, the outer mandrel portion may also have a flat inner guide surface, specifically the inner guide surface together forming a square constant cross section for the central insertion space.

[0035] These connecting parts may include, for example, complementary convex and concave portions configured to clamp each other.

[0036] In another preferred embodiment, the complementary connection may include a convex key portion and a concave cavity portion, wherein the size of the concave cavity portion is excessive relative to the convex key portion to allow the convex key portion to move laterally within the concave cavity portion in a slidingly engaged manner between an expanded winding state and a contracted removal state. This ability of the convex key portion to move laterally within the concave cavity portion via a sliding engagement allows for precise control of the inward movement of the outer mandrel portion. Furthermore, this automatically defines and delineates the expanded winding state when the convex key portion is positioned against the outermost lateral wall of the concave cavity portion, and automatically defines and delineates the contracted removal state when the convex key portion is positioned against the innermost lateral wall of the concave cavity portion. The lateral outward constraint of the outer mandrel portion by the connection, combined with the lateral inward constraint of the inner mandrel portion inserted by the form-fitting insertion of the outer mandrel portion, provides stability and secure positioning of the outer mandrel portion, thereby providing a stable surface for winding and thus preventing fiber twisting during winding.

[0037] Preferably, the convex and concave connecting parts are slidable relative to each other in the axial direction. This allows for easy and quick disassembly of all outer mandrel parts from each other when needed.

[0038] In addition, the convex key portion and the concave cavity portion can be L-shaped, wherein the concave cavity portion has a larger dimension in the lateral direction to allow the convex key portion to move laterally within the concave cavity portion between an expanding wound state and a contracted removal state. This hook-like shape of the convex and concave joint portion prevents the outer mandrel portion from falling off when the inner mandrel portion is removed.

[0039] In a further embodiment, at least two outer mandrel portions may have only one pair of opposing elongated outer mandrel portions that define an entire elongated central insertion space between the two elongated outer mandrel portions when their opposing abutting surfaces are facing each other and spaced apart from each other in an expanded wound state. This reduces the number of components.

[0040] In an alternative embodiment, at least two outer mandrel portions may have two pairs of opposing elongated outer mandrel portions, the four elongated outer mandrels in these two pairs of opposing elongated outer mandrel portions defining the entire elongated central insertion space together when the two pairs of opposing elongated outer mandrel portions are positioned such that their opposing abutting surfaces are opposite each other and spaced apart from each other. This allows the external dimensions of the winding surface to decrease in all directions as the removal state moves toward the contracted outer mandrel portions.

[0041] In another embodiment, the abutment surface may be located in a lateral orientation plane different from that of the guide surface. For example, in the case where the inner mandrel portion has a vertically oriented outer guide surface and a square cross-section, the abutment surface may extend in alignment with the corner of the square cross-section, i.e., at a 45-degree angle relative to the orientation of the outer guide surface.

[0042] In a preferred embodiment, the inner mandrel portion may be configured in the axial direction to extend from the opposite outer end of the outer mandrel portion to form a drive shaft for rotating the mandrel assembly in an expanded wound state during fiber winding.

[0043] The drive shaft, serving as the inner mandrel section, provides a stable and rigid support structure for the outer mandrel section. This enhances the overall rigidity of the mandrel assembly in the expanded winding state and provides excellent support for the tight winding of fibers during the winding process, thus contributing to the quality of the final product without deformation or misalignment. The stable support of the drive shaft also allows for good control of fiber tension during winding and makes the mandrel assembly easier to handle and manipulate throughout the production process.

[0044] In a preferred embodiment, the inner mandrel portion may be made of metal, such as an extruded metal bar with a square cross-section, while the outer mandrel portion may be made of plastic, for example, manufactured by molding or 3D printing.

[0045] In a preferred embodiment, the profile of the outer winding surface may vary along the axial and / or circumferential directions. In particular, it may be bilaterally symmetrical. This can be advantageous in the production of hollow fiber wound composite parts with specific profile shapes, such as the frame sections, handlebars, rims, and other structural elements of a bicycle's aerodynamic design.

[0046] Optionally, the inner and / or outer mandrel portions may comprise multiple segments in the axial direction, which are connected to each other, for example, by metal pins. These segments can be 3D printed separately and then joined together. Multiple segments facilitate the production of relatively long mandrel portions. Specifically, each segment can be up to 50 cm or longer. This allows for winding processes on truly long lengths, such as 2.5 m (5 segments), providing high winding efficiency and great flexibility in the external shape of the winding surface.

[0047] As seen in the axial direction, the multiple segments of the mandrel portion can preferably begin and end at different points. This helps to ensure a secure assembly of the outer mandrel portion and makes kinking less likely.

[0048] Further preferred embodiments of the invention are described in the dependent claims. The invention also relates to the method according to claim 14. Attached Figure Description

[0049] The invention will now be explained in more detail by describing some exemplary embodiments in a non-limiting manner with reference to the accompanying drawings, in which: Figures 1a to 1f Multiple states of a removable fiber-wound mandrel assembly having an inner mandrel portion and two outer mandrel portions according to an embodiment of the present invention are shown. Figure 2a A cross-sectional view of a removable fiber-wound mandrel assembly having an inner mandrel portion and two outer mandrel portions according to an embodiment of the present invention is shown schematically. Figure 2b It shows according to Figure 2a A perspective view of the removable fiber-wound mandrel assembly; Figure 3a A perspective view of a removable fiber-wound mandrel assembly having an inner mandrel portion and four outer mandrel portions according to an embodiment of the present invention is shown. Figure 3b Schematic illustration based on Figure 3a A cross-sectional view of the removable fiber-wound mandrel assembly; Figures 4a to 4c A perspective view of another embodiment of the removable fiber-wound mandrel assembly according to the present invention is shown; Figures 5a to 5d Schematic illustration Figures 4a to 4c Cross-sectional views of the removable fiber-wound mandrel assembly in multiple states; Figure 5c' It shows Figure 5c A three-dimensional image; Figure 6 It shows Figure 4a The view shows that the two sets of outer mandrel sections are connected one after the other in the axial direction. Figure 7 A perspective view of another embodiment of the removable fiber-wound mandrel assembly having an inner mandrel portion and two outer mandrel portions according to the present invention is shown; and Figure 8 The inner mandrel portion has been removed. Figure 7 The outer mandrel part of the component. Detailed Implementation

[0050] exist Figures 1a to 1f In the figure, a removable fiber-wound mandrel assembly is shown with reference numeral 1. In this embodiment, the mandrel assembly 1 includes a pair of elongated outer mandrel portions 2 that define a square elongated central insertion space 3 therebetween. The outer mandrel portions 2 have a flat inner guide surface 4. The inner guide surface 4 of the outer mandrel portions 2 forms a square constant cross-section for the central insertion space 3. Figure 1a and Figure 1b The outer mandrel portion 2 is shown in an expanded wound state. In this expanded wound state, the outer mandrel portion 2 defines an outer winding surface 6 for winding fibers during the production of the hollow fiber wound composite component 7. Adjacent outer mandrel portions 2 are shown as having elongated facing abutment surfaces 5 between them. In the expanded wound state, the opposing abutment surfaces 5 of adjacent outer mandrel portions 2 are opposite to each other and spaced apart. The spacing between the opposing abutment surfaces 5 of the outer mandrel portions 2 can advantageously allow for local cutting of the wound fibers passing axially through the outer end of the newly produced hollow fiber wound composite component 7. The spacing between the opposing abutment surfaces 5 also allows the outer mandrel portions 2 to shift laterally between an expanded wound state and a contracted removal state, in which the opposing abutment surfaces 5 abut against each other, as shown in the contracted removal state. Figures 1c to 1d As shown. In this contracted removal state, the outer mandrel portion 2 defines a reduced outer winding surface 6 for removing the outer mandrel portion 2 from the hollow fiber wound composite component 7 in the axial direction.

[0051] A complementary coupling portion 8 is disposed between the opposing abutting surfaces 5 of adjacent outer mandrel portions 2. When in an expanded, wound state, the coupling portion 8 connects the adjacent outer mandrel portions 2 and restricts their movement in a laterally outward direction. Figure 1c As shown, the connecting portion 8 includes a convex key-shaped portion 9 and a concave cavity portion 10. The concave cavity portion 10 is larger than the convex key-shaped portion 9. Therefore, the convex key-shaped portion 9 can be displaced laterally within the concave cavity portion 10, thereby shifting the outer mandrel portion 2 between an expanded winding state and a contracted removal state. The convex key-shaped portion 9 and the concave cavity portion 10 are L-shaped, and the concave cavity portion 10 has a larger dimension in the lateral direction to allow the convex key-shaped portion 9 to be displaced laterally within the concave cavity portion 7, thereby shifting the outer mandrel portion 2 between an expanded winding state and a contracted removal state.

[0052] like Figures 1a to 1d As shown, the outer winding surface 6 of the outer mandrel portion 2 is shaped. This advantageously allows for the manufacture of hollow fiber wound composite parts 7 with specific profile shapes, such as frame parts, handlebars, wheel rims, and other structural elements for the aerodynamic design of bicycles.

[0053] An elongated inner mandrel portion 11 is disposed within the central insertion space 3. The inner mandrel portion 11 has a central axis X and extends in the axial direction. The inner mandrel portion 11 has a flat outer guide surface 12, which together form a square cross-section for the inner mandrel portion 11. The inner mandrel portion 11 has a constant cross-section, which is configured to engage in a sliding manner along the inner guide surface 4 of the outer mandrel portion 2 via its outer guide surface 12 when the outer mandrel portion 2 is in its expanded wound state. In this embodiment, the inner mandrel portion 11 extends axially beyond the opposite outer end of the outer mandrel portion 2 to form a drive shaft. During fiber winding for forming the hollow fiber wound composite material component 7, the inner mandrel portion 11 rotates about its central axis X, thereby simultaneously rotating the outer mandrel portion 2.

[0054] According to the invention, the inner guide surface 4 of the outer mandrel portion 2, the outer guide surface 12 of the inner mandrel portion 11 opposite to the inner guide surface 4, and the complementary connecting portion 8 all extend parallel to the central axis X. This allows the inner mandrel portion 11 to be completely removed from the central insertion space 3 during demolding, while its outer guide surface 12 slides axially along the inner guide surface 4 of the outer mandrel portion 2. After the inner mandrel portion 11 has been completely pulled out of the central insertion space 3, the free central insertion space 3 allows the outer mandrel portion 2 to move laterally inward easily and quickly, thus eliminating contact with the hollow fiber wound composite component 7. The outer mandrel portion 2 can then be easily, quickly, and carefully pulled out of the hollow fiber wound composite component 7 in the axial direction. This helps reduce friction between the inner wall of the hollow fiber wound composite component 7 and the contracted winding surface 6, which is then defined by the outer mandrel portion 2 in its contracted removal state, and thus helps to ensure the integrity of the newly produced hollow fiber wound composite component 7.

[0055] exist Figure 2a and Figure 2b The image shows an embodiment of a removable fiber-wound mandrel assembly 1, which has a pair of elongated outer mandrel portions 2' and two pairs of connecting portions 8 disposed at corresponding opposing abutting surfaces 5 of these outer mandrel portions 2'.

[0056] exist Figure 3a and Figure 3b The image shows an embodiment of a removable fiber-wound mandrel assembly 1 having two pairs of elongated outer mandrel portions 2', 2" . The two pairs of outer mandrel portions 2', 2" also have inner guide surfaces 4, which together define an elongated central insertion space 3 when the opposing abutting surfaces 5 are facing each other. Having two pairs of outer mandrel portions 2', 2" allows the external dimensions of the winding surface 6 to decrease in all directions as it moves toward its contracted removal state. Figure 3a and Figure 3b As shown, when in an expanded winding state, the two outer mandrel portions 2', 2" are positioned such that the abutting surfaces 5 of the adjacent outer mandrel portions 2', 2" are spaced apart. In this embodiment, the abutting surfaces 5 extend in alignment with the corners of the square cross-section of the inner mandrel portion 11, that is, they extend at a 45-degree angle relative to the orientation of the inner guide surface 4.

[0057] Figure 3b A cross-section of the outer mandrel portions 2', 2" of the removable fiber-wound mandrel assembly 1 is shown, wherein the inner mandrel portion 11 is still to be inserted, but the outer mandrel portions 2', 2" are already in their expanded wound state. Connecting portions 8 are provided on the abutment surfaces in the form of L-shaped convex key-like portions 9 and L-shaped concave cavity portions 10. Such connecting portions 8 are provided on each adjacent abutment surface. All convex key-like portions 9 extend in the same lateral direction. Therefore, after the inner mandrel portion 11 is removed, the first pair of opposing outer mandrel portions 2' can be displaced inward in the lateral direction to eliminate contact between the first pair of opposing outer mandrel portions 2' and the newly manufactured hollow fiber-wound composite component (not shown here). The pair of opposing outer mandrel portions 2' can then be removed from the hollow fiber-wound composite component by sliding the convex key-like portions 9 axially from the concave cavity portions 10. After the first outer mandrel portion 2' is removed, the remaining second outer mandrel portion 2" can then be displaced inward in the lateral direction to also eliminate contact with the fiber-wound composite component, and then the second outer mandrel portion 2" is removed from the material component in the axial direction.

[0058] Figures 4a to 4c , Figures 5a to 5d , Figure 5c' and Figure 6 An alternative embodiment of a removable fiber-wound mandrel assembly 1 is shown, which includes a first outer mandrel portion 2' (in... Figure 4b (highlighted in the middle) and the second outer mandrel part 2 (in the middle) Figure 4c (Highlighted in the image). In this embodiment, the opposing abutting surfaces 5 of adjacent outer mandrel portions 2 abut against each other in an expanded, wound state. A connecting portion 8 is provided at corresponding guide surfaces 4, 12 of the inner mandrel portion 11 and the outer mandrel portion 2. The connecting portion 8 allows the outer mandrel portion 2 to be directly connected to the inner mandrel portion 11, thereby restricting the outer mandrel portion 2 in a laterally outward direction when in an expanded, wound state. The connecting portion 8 includes a circular mushroom-shaped convex portion 9 and a complementary mushroom-shaped concave portion 10, the circular mushroom-shaped convex portions extending from their respective guide surfaces 4 into the insertion space 3, and the complementary mushroom-shaped concave portions recessed into the inner mandrel portion 11 at their respective guide surfaces 12 (see also...). Figures 5a to 5d ).

[0059] The inner guide surface 4 of the outer mandrel portion 2, the outer guide surface 12 of the inner mandrel portion 11 opposite to the inner guide surface 4, and the complementary connecting portion 8 all extend parallel to the central axis X.

[0060] Figures 5a to 5d The embodiment shown illustrates the sequential steps of removing the inner mandrel portion 11 and multiple sets of outer mandrel portions 2', 2'" from a hollow fiber wound composite material component (not shown), with the connecting portion 8 provided at corresponding guide surfaces 4, 12 of the inner mandrel portion 11 and the outer mandrel portion 2 according to FIG4. Figure 5a In the process, the outer mandrel portion 2 is in its expanded, wound state, while the inner mandrel portion 11 is disposed in the central insertion space 3 defined by the outer mandrel portion 2. The connecting portion 8 connects the outer mandrel portion 2 to the inner mandrel portion 11.

[0061] The inner guide surface 4 of the outer mandrel portion 2 that defines the central insertion space 3, the outer guide surface 12 of the inner mandrel portion 11 that is opposite to the inner guide surface 4, and the complementary connecting portion 8 all extend parallel to the central axis. The inner mandrel portion 11 can be removed from the central insertion space 3 by sliding the inner mandrel portion 11 along the inner guide surface 4 of the outer mandrel portion 2 in the axial direction.

[0062] exist Figure 5b The diagram shows the outer mandrel portion 2 after the inner mandrel portion 11 has been removed. In cross-section, the opposing abutment surfaces 5 of the outer mandrel portion 2 taper slightly, causing them to converge toward the outer winding surface 6 of the outer mandrel portion 2. This allows the first outer mandrel portion 2' to move laterally inward smoothly, while simultaneously allowing the second outer mandrel portion 2'" to move laterally inward until the mushroom-shaped protrusions 9 of the four outer mandrel portions 2' and 2'" contact each other and cannot move further inward (see...). Figure 5c , Figure 5c' In this state, the first outer mandrel portion 2' can be slidably removed from the hollow fiber wound composite material (not shown) along the opposing abutment surfaces 5 in the axial direction. After the first outer mandrel portion 2' is removed, the second outer mandrel portion 2" can be further displaced inward, thereby further eliminating contact with the hollow fiber wound composite material component (not shown), until the mushroom-shaped protrusions 9 of the second outer mandrel portion 2" contact each other and cannot move further inward (see...). Figure 5d The second outer mandrel portion 2 can then be removed entirely from the composite component (not shown).

[0063] Figure 4 to Figure 6The outer winding surface 6 in this embodiment is shown to be bilaterally symmetrical. This advantageously allows for the manufacture of hollow fiber wound composite parts with specific profile shapes, such as frame sections, handlebars, rims, and other structural elements for aerodynamic designs of bicycles. Furthermore, as seen in the axial direction, the outer mandrel portion 2 has multiple removable sections. Figure 6 The image shows a set of outer mandrel sections 2 on the left and right sides.

[0064] Figure 7 and Figure 8 A removable fiber-wound mandrel assembly 1 with an outer mandrel portion 2 is shown, wherein the connecting portion 8 is provided only at one of the corresponding guide surfaces 4, 12 of the inner mandrel portion 11 and the outer mandrel portion 2. Figure 7 and Figure 8 In the middle, the outer mandrel portion 2 is in an expanded winding state, so that the relative contact surfaces 5 of the outer mandrel portion 2 are then positioned apart.

[0065] Besides the embodiments shown and described, many variations are possible. For example, the size and shape of various components can be changed. Advantageous aspects of the illustrated embodiments can also be combined. Instead of using L-shaped or mushroom-shaped couplings, other types of sliding fittings, such as T-shaped or J-shaped couplings, can be used as couplings. The number of outer mandrel portions can also be varied, for example, having six outer mandrel portions, or having an odd number of outer mandrel portions, such as three or five outer mandrel portions. All kinds of other materials can be used for the inner and outer mandrel portions. However, preferably, the inner mandrel portion is made of metal and / or the outer mandrel portion is made of plastic.

[0066] It should be understood that various changes and modifications can be made to the presently preferred embodiments without departing from the scope of the invention, and are therefore apparent to those skilled in the art. Thus, these changes and modifications are intended to be covered by the appended claims.

[0067] The disclosure of Dutch patent application No. N2036634, which claims priority to this application, is incorporated herein by reference.

[0068] Where a technical feature mentioned in any claim is followed by a reference symbol, those reference symbols are included only for the purpose of increasing the comprehensibility of the claim, and therefore, such reference symbols do not have any limiting effect on the interpretation of each element identified by way of example by such reference symbols.

Claims

1. A removable fiber-wound mandrel assembly (1) for winding fibers around the removable fiber-wound mandrel assembly during the production of a hollow fiber-wound composite component (7), the hollow fiber-wound composite component being particularly a carbon fiber reinforced bicycle component, the removable fiber-wound mandrel assembly comprising: • At least two elongated outer core shaft portions (2) together define the elongated center insertion space (3); as well as • The elongated inner spindle portion (11) has a central axis (X) extending in the axial direction and a lateral direction perpendicular to the axial direction. The outer mandrel portion (2) is capable of shifting between an expanding wound state and a contracted removal state along the lateral direction. The outer mandrel portion and / or the inner mandrel portion (11) are provided with complementary connecting portions (8), which are configured to restrict the outer mandrel portion (2) in the lateral outward direction in the expanded winding state. Wherein, the outer mandrel portion (2) defines an outer winding surface (6) in the expanded winding state, the outer winding surface being used to wind fibers around the outer winding surface during the production of the hollow fiber wound composite material component, and The outer mandrel portion (2) defines a reduced outer winding surface (6) in the contracted removal state for removing the mandrel portion from the hollow fiber wound composite component along the axial direction. Its features are, The inner guide surface (4) of the outer mandrel portion (2) that defines the central insertion space (3), the outer guide surface (12) of the inner mandrel portion (11) that is opposite to the inner guide surface (4), and the complementary connecting portion (8) all extend parallel to the central axis (X). The inner mandrel portion (11) has a constant cross-section, which is configured such that when the outer mandrel portion (2) is in the expanded winding state, the outer guide surface (12) of the inner mandrel portion engages with the inner guide surface (4) that together defines the central insertion space (3) in a sliding manner. The inner mandrel portion (11) can be removed from the central insertion space (3), and the outer guide surface (12) of the inner mandrel portion slides along the inner guide surface (4) of the outer mandrel portion (2) in the axial direction, so that after the inner mandrel portion (11) is removed from the central insertion space (3), the outer mandrel portion (2) can be displaced in the laterally inward direction toward the retracted removal state, while reducing the central insertion space (3).

2. The removable fiber-wound mandrel assembly (1) according to claim 1, wherein, Adjacent outer mandrel portions (2) include elongated opposing abutment surfaces (5) between adjacent outer mandrel portions, the opposing abutment surfaces (5) also extending parallel to the central axis (X), wherein the opposing abutment surfaces (5) are configured to be spaced apart from each other in the expanded winding state, and wherein the opposing abutment surfaces (5) are configured to abut against each other in the contracted removal state.

3. The removable fiber-wound mandrel assembly (1) according to claim 2, wherein, The complementary connection (8) is disposed between the opposing abutting surfaces (5) of adjacent outer mandrel portions in the outer mandrel portion (2).

4. The removable fiber-wound mandrel assembly (1) according to claim 3, wherein, The complementary connection portion (8) includes a convex key portion (9) and a concave chamber portion (10), wherein the size of the concave chamber portion (10) is larger than the size of the convex key portion (9) to allow the convex key portion (9) to move within the concave chamber portion (10) in the lateral direction between the expanded winding state and the contracted removal state.

5. The removable fiber-wound mandrel assembly (1) according to claim 4, wherein, The convex key-shaped portion (9) and the concave cavity portion (10) are L-shaped, wherein the concave cavity portion (10) has a larger dimension in the lateral direction to allow the convex key-shaped portion (9) to move within the concave cavity portion (10) in the lateral direction between the expanded winding state and the contracted removal state.

6. The removable fiber-wound mandrel assembly (1) according to any one of claims 3 to 5, wherein, The inner mandrel portion (11) has a flat outer guide surface (12), and in particular, the flat outer guide surface together forms a square constant cross section of the inner mandrel portion (11).

7. The removable fiber-wound mandrel assembly (1) according to any one of claims 3 to 6, wherein, The outer mandrel portion (2) has a flat inner guide surface (4), and in particular, the flat inner guide surface together forms a square constant cross section of the central insertion space (3).

8. The removable fiber-wound mandrel assembly (1) according to any one of claims 2 to 7, wherein, The outer mandrel portions (2) are provided with a pair of elongated outer mandrel portions, which together define the central insertion space (3) of the elongated mandrel portions when positioned such that the opposing abutting surfaces (5) are opposite to each other.

9. The removable fiber-wound mandrel assembly (1) according to any one of claims 2 to 7, wherein, Two pairs of elongated outer mandrel portions (2', 2") are provided, which together define the elongated central insertion space (3) when positioned such that the opposing abutting surfaces (5) are opposite to each other.

10. The removable fiber-wound mandrel assembly (1) according to any one of claims 2 to 9, wherein, The abutting surface (5) is located in a plane with a different lateral orientation than the guiding surface, and in particular, the abutting surface is at a 45-degree angle to the guiding surface.

11. The removable fiber-wound mandrel assembly (1) according to any one of the preceding claims, wherein, The inner mandrel portion (11) extends from the two opposite outer ends of the outer mandrel portion (2) in the axial direction to form a drive shaft for rotating the mandrel assembly (1) in the expanded winding state during fiber winding.

12. The removable fiber-wound mandrel assembly (1) according to any one of the preceding claims, wherein, The inner mandrel portion (11) is made of metal, and the outer mandrel portion (2) is made of plastic.

13. The removable fiber-wound mandrel assembly (1) according to any one of the preceding claims, wherein, The outer winding surface (6) has a shaped profile.

14. A method for producing a hollow fiber-wound composite material part (7) using a removable fiber-wound mandrel assembly (1) according to any one of the preceding claims, the method comprising the steps of: - The inner mandrel portion (11) is slid along the inner guide surface (4) in the axial direction through the outer guide surface (12) of the inner mandrel portion into the center insertion space (3), while the form fit of the inner mandrel portion (11) in the center insertion space (3) and the complementary connection portion (8) together lock the outer mandrel portion (2) to form the expanded winding state; - Wrap the fibers around the outer winding surface (6) of the outer mandrel portion (2); - The inner mandrel portion (11) is slid out from the center insertion space (3) along the inner guide surface (4) via the outer guide surface (12) of the inner mandrel portion; - The outer mandrel portion (2) is moved toward each other in the lateral inward direction, while the center insertion space (3) is reduced to form the contracted removal state; as well as - Remove the hollow fiber wound composite material component (7) from the outer mandrel portion (2) which is in the shrinkage removal state.

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