A bicycle rim made of a composite material and including a wing portion having a reinforcing structure

Abstract

A bicycle rim made of a composite material and including a wing having a reinforcement structure, which is made of a plurality of layered structures of the composite material, each structure being formed by one or more layers of structural fibers incorporated in a polymer material. The bicycle rim includes a radially outer peripheral channel having an upper bridge that extends between two opposite wings for holding a tire. The peripheral channel includes an inner layered structure and at least one wound layered structure. The inner layered structure extends from one wing to the other wing, and the at least one wound layered structure is wound around the inner layered structure at least at the end of the wing. The inner layered structure and the wound layered structure are included in the plurality of layered structures. The wound layered structure at the end of the wing not only provides reinforcement for the wing itself, but also protects the end of the wing from possible delamination, and also prevents this phenomenon from occurring in the case of a traumatic event, such as a tire burst or a particularly severe impact of the rim by a rigid obstacle.

Description

Technical Field

[0001] The present invention relates to a bicycle wheel made of a composite material. In particular, the composite material is a material comprising structural fibers (such as carbon fibers, glass fibers, boron fibers, aramid fibers, ceramic fibers, and combinations thereof) incorporated in a thermosetting polymer material matrix. Background Art

[0002] In this patent text, spatial indications, in particular spatial indications such as the radial direction, the axial direction, and the circumferential direction, are given with reference to the axis of rotation of the rim, i.e., the axis of rotation of the bicycle wheel to which the rim belongs.

[0003] Composite materials are increasingly widely used in the manufacture of parts and components of bicycles to obtain parts that are very light and strong. Rims are now increasingly made of these materials.

[0004] Manufacturing a rim using a composite material allows for shaping in a mold. The composite material is arranged in the mold in an uncured state so that it adopts the shape of the mold; this operation is possible because the composite material can be very easily deformed in the uncured state. Subsequently, the mold is closed and the composite material is compressed to force it to assume the desired shape. Then, the mold with the composite material is subjected to a heat treatment (also known as curing), which causes crosslinking (polymerization) of the polymer material matrix, and thus locks the structural fibers in a predetermined position. Once extracted from the mold, the rim is finally subjected to possible machining (usually milling and polishing) until it reaches its final shape.

[0005] The prior art provides two types of molds: axial molds and radial molds. In an axial mold, two shells are arranged together and pressed against the composite material in the axial direction of the rim. In a radial mold, there is a radially inner shell and a radially outer shell, which are arranged together and pressed against the composite material in the radial direction of the rim; if the rim has a geometry providing one or more closed inner channels (so-called pockets), an inflatable insert is used. For both types of molds, for geometric construction reasons, the shells can (or must) be made of many separable parts; for the same reason, mold inserts (also known as cores) can (or must) be used to manufacture undercut parts, such as flanges for holding the tire.

[0006] Bicycle rims are particularly fragile components because they are subjected to very diverse and variable stresses. In addition, the two wheels together constitute a large part of the total mass of the bicycle. Therefore, companies in this field have been seeking improvements so that the wheels can be made lighter and stronger. Summary of the Invention

[0007] Accordingly, the present invention relates to a rim according to claim 1; in a second aspect, the present invention relates to a method for producing a rim according to claim 13. Preferred features of the rim and the method are given in the dependent claims.

[0008] More specifically, a bicycle rim is made of a plurality of laminated structures of composite material, each laminated structure being formed by one or more layers of structural fibers incorporated in a polymeric material, the bicycle rim comprising a radially outer peripheral channel, the radially outer peripheral channel comprising an upper bridge that extends between two opposite flanges for holding a tire, and characterized in that the peripheral channel comprises an inner laminated structure and a wound laminated structure, wherein the inner laminated structure extends from one flange to the other flange, and the wound laminated structure is wound at least at the ends of the flanges around the inner laminated structure and closes on itself, and the inner laminated structure and the wound laminated structure are included in the plurality of layer structures.

[0009] In the context of the present specification and the appended claims, the term "laminated structure" refers to a group of one or more single layers of structural fibers incorporated in a matrix of a thermosetting or thermoplastic polymeric material (preferably a thermosetting resin).

[0010] The wound laminated structure on the end of the flange not only provides reinforcement to the flange itself, but also protects the end of the flange from possible delamination, preventing delamination in the event of a traumatic event such as a tire burst or a particularly severe impact of the rim against a rigid obstacle.

[0011] In addition to the strengthening and protective effect on the flange, a very significant hardening of the entire peripheral channel is obtained due to the substantially box-shaped structure produced by the wound laminated structure around the inner laminated structure.

[0012] Preferably, the wound laminated structure closes on itself by overlapping an initial flap with a final flap. In this way, the box-shaped structure is complete and has closed on the wound laminated structure, thus ensuring the maximum structural strength of the peripheral channel.

[0013] In a preferred embodiment, the rim comprises: a closed radially inner channel that is integral with the peripheral channel in its radially inner position; the closed channel being defined by two opposite side walls that are connected to each other by an upper bridge and in a radially inner position by a lower bridge; the closed channel comprising a closed-channel laminated structure that extends along at least a portion of the lower bridge, the side walls, and the upper bridge, and the closed-channel laminated structure is included in the plurality of laminated structures. The closed-channel laminated structure thus has a particularly strong structure because it is substantially box-shaped.

[0014] Preferably, the closed channel laminate structure terminates at the peripheral channel with an initial flap and a final flap, and the initial and final flaps of the closed channel laminate structure are arranged side by side with the wound laminate structure. The closed channel laminate structure is thus connected to the peripheral channel at the upper bridge, such that the closed channel and the peripheral channel cooperate to impart maximum strength to the rim.

[0015] In one embodiment, the initial flap is spaced apart from the final flap so as to expose a portion of the wound laminate structure towards the interior of the closed channel. In another embodiment, the initial flap overlaps the final flap such that the interior of the closed channel is completely enclosed by the closed channel laminate structure. Although overlapping ensures maximum structural strength since a closed box-like structure is formed solely by the closed channel laminate structure, spacing apart may be preferred for easier construction: in this case, in fact, the closed channel laminate structure is more easily movable in the mold under the thrust of the pressing bag around which it is wound during shaping and prior to curing.

[0016] Preferably, the peripheral channel includes two inner wing laminate structures, each inner wing laminate structure overlapping the inner laminate structure at each of the respective wings and being enclosed by the wound laminate structure together with the inner laminate structure, and the inner wing laminate structures are included in the plurality of laminate structures. The presence of these laminate structures increases the structural strength of the wings, which are often subject to greater stress relative to the rest of the peripheral channel; their positioning within the wound laminate structure ensures maximum mechanical interaction with the wound laminate structure as well as with the inner laminate structure.

[0017] Preferably, the rim includes an outer laminate structure that extends externally from one of the wings to one of the sidewalls, to the lower bridge, to the other sidewall, and to the other wing; the outer laminate structure overlaps the closed channel laminate structure at the closed channel and covers the wound laminate structure at the wings, and the outer laminate structure is included in the plurality of laminate structures. The contribution of such an outer laminate structure to the overall structural strength of the rim is very important as it joins the peripheral channel and the closed channel together.

[0018] Preferably, the rim includes two outer wing laminate structures, each outer wing laminate structure overlapping the wound laminate structure at each wing and covering the closed channel laminate structure at the closed channel, and the outer wing laminate structures are included in the plurality of laminate structures below the outer wing laminate structures. These outer wing laminate structures are used to strengthen the wings but do not determine the discontinuity on the outside of the rim since they are located below the outer laminate structure.

[0019] Preferably, the rim includes a lower bridge delamination structure at the lower bridge, and the lower bridge delamination structure is included in the plurality of delamination structures. It is useful to strengthen the area of the lower bridge through this delamination structure because the spokes connecting the wheels are in this area, which can determine even very high local stresses.

[0020] In one embodiment, the lower bridge delamination structure is arranged between the outer delamination structure and the closed channel delamination structure. In another embodiment, the lower bridge delamination structure overlaps with the closed channel delamination structure on the opposite side relative to the outer delamination structure. This interposition ensures maximum structural strength due to better interaction with adjacent delamination structures. For easier construction, it may be preferred to be positioned on the opposite side relative to the outer delamination structure (i.e., positioned inside the closed channel) because it is easier to achieve correct positioning in the mold.

[0021] Preferably, the rim includes two circumferential inserts, each circumferential insert being arranged at the convergence area of the upper bridge and one of the flanges; each insert is formed by directional structural fibers incorporated in the polymer material, and the directional structural fibers are oriented in the circumferential direction of the rim.

[0022] If the rim is also provided with a closed channel, then it preferably includes two circumferential inserts, each circumferential insert being arranged at the convergence area of one of the sidewalls and the upper bridge and a flange; each insert is formed by directional structural fibers incorporated in the polymer material; each insert is inserted between the closed channel delamination structure and the winding delamination structure, below the outer delamination structure, and the directional structural fibers are oriented in the circumferential direction of the rim.

[0023] The above-mentioned circumferential inserts help to provide high mechanical strength, especially in the circumferential direction.

[0024] As described, the various delamination structures of the composite material may include one or more layers of structural fibers incorporated in the polymer matrix; the structural fibers may be unidirectional, oriented at a predetermined angle, or woven into a fabric.

[0025] Preferably, the wings have respective ends that are folded towards each other at a predetermined acute angle α with respect to the axial direction of the rim, and the peripheral channel includes a pair of circumferential protrusions having surfaces that are inclined at an acute angle β with respect to the axial direction of the rim, where α > β. The folded ends of the wings and the protrusions on the peripheral channel facilitate the correct and stable positioning of the tire; the indicated angles enable this function to be maintained without causing an obstruction when the freshly formed rim must be released from the mold and especially from the mold insert. Generally, the smaller the angle α, the better the tire is held; however, an angle α equal to zero causes difficulties in removing the mold insert. The presence of the aforementioned protrusions enables excellent holding of the tire (also in the case where the angle α is greater than zero), while facilitating the extraction of the mold insert. It should be noted that the features related to the inclination of the ends of the wings and those related to the protrusions can also be advantageously used on rims different from the rim of the present invention; thus, these features by themselves constitute an invention.

[0026] Preferably, the angle α is equal to approximately 20 degrees. Preferably, the difference α - β is between 0.5 and 4 degrees, more preferably equal to approximately 2 degrees. These two features, either alone or in combination, enable an optimal compromise to be achieved between holding the tire and the easy extractability of the mold insert.

[0027] Preferably, each protrusion is formed using a wound laminate structure, but can also be made by thickening a thermosetting resin.

[0028] Preferably, the wings have rounded ends. This configuration is not only the simplest configuration obtained with the rim according to the present invention, where the ends of the wings are provided with a wound laminate structure, but it is also a configuration in which this rim can be obtained directly without the need for extensive machining (other than possible polishing) after molding; polishing is considered unimportant because it only has a surface effect on the polymer matrix and does not reach the structural fibers.

[0029] In a second aspect of the present invention, a method for manufacturing a bicycle rim made of a composite material based on structural fibers incorporated in a polymer material, the rim including a radially outer peripheral channel that includes an upper bridge extending between two opposite wings for holding a tire, the method comprising the following steps:

[0030] a) providing: a radial mold shaped according to the contour of the bicycle rim; at least one pressing element; and at least one mold insert for forming in the mold an end region adapted to form a wing;

[0031] b) Lay a wound laminate structure of uncured composite material on the working plane, the uncured composite material comprising structural fibers incorporated in a polymeric material;

[0032] c) Lay an inner laminate structure of the uncured composite material on the wound laminate structure, the uncured composite material comprising structural fibers incorporated in a polymeric material, the length of the inner laminate structure being equal to the length of the wound laminate structure, and the width of the inner laminate structure being less than half of the width of the wound laminate structure;

[0033] d) Fold two opposite flaps of the wound laminate structure in the width direction over the inner laminate structure so that they overlap each other;

[0034] e) Arrange the pressing element and the wound laminate structure in the mold, wherein the inner laminate structure is included and folded in a C-shape over the pressing element;

[0035] f) Position the at least one mold insert in the mold such that the wound laminate structure enclosing the inner laminate structure reaches the end region of the mold;

[0036] g) Close the mold and apply pressure with the pressing element on the wound laminate structure and the inner laminate structure to cause the polymeric material to flow and move the structural fibers in the direction of the end region of the mold until the entire space between the mold and the at least one mold insert is occupied;

[0037] h) Subject the mold to a pressure and temperature profile in order to cause the setting of the polymeric material;

[0038] i) Open the mold;

[0039] j) Remove the at least one mold insert;

[0040] k) Remove the molded bicycle rim.

[0041] Due to this method, in particular features b) to g), a substantially finished rim can be obtained from the mold without any machining (except possibly polishing). In particular, the flanges do not require milling to define their final shape. In this way, not only are processes that increase the processing time and cost in each case avoided, but in particular at the ends of the flanges, the structural fibers are prevented from being exposed to air due to the removal of the polymeric matrix; in practice, exposure to air would over time damage the integrity of the structural fibers, triggering delamination phenomena and thus shortening the life of the rim.

[0042] Preferably, the method further comprises the following steps:

[0043] a1) providing two circumferential inserts, wherein each insert is formed from directional structural fibers incorporated into a polymer material, wherein the directional structural fibers are oriented in a circumferential direction;

[0044] f1) Positioning a circumferential insert in the mould at the convergence area of the upper bridge and one of the wings, between the wound layer structure enclosing the inner layer structure and the pressing element.

[0045] As described above, the two circumferential inserts not only strengthen the rim itself, but also allow the application of a thrust of the pressing element to the wound layered structure (enclosing the inner layered structure), in particular in the direction of the end zone of the mould, thereby facilitating its correct filling and therefore the correct forming of the wing.

[0046] Preferably, the method further comprises the following steps:

[0047] d1) Providing a closed channel layered structure which is wound onto a pressing element.

[0048] In this way, a rim is obtained having two channels: a radially outer peripheral channel and a closed radially inner channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The other features and advantages of the present invention will become more apparent from the following description of some preferred embodiments of the present invention. In the accompanying drawings:

[0050] Figure 1 is a schematic cross-sectional view of a rim according to a first embodiment of the present invention;

[0051] Figure 2 yes Figure 1 An enlarged cross-sectional view of only the radially outer portion of the rim;

[0052] Figure 3 yes Figure 1 Another enlarged cross-sectional view of only the radially outer portion of the rim;

[0053] Figure 4 yes Figure 1 An enlarged cross-sectional view of only the radial inner portion of the rim;

[0054] Figure 5 is a schematic cross-sectional view of a rim according to a second embodiment of the present invention;

[0055] Figure 6 yes Figure 2 A schematic cross-sectional view of a variation of the rim shown in FIG.

[0056] Figure 7 yes Figure 4 A schematic cross-sectional view of a variation of the rim shown in FIG.

[0057] Figure 8 and Figure 9 are during two consecutive steps of shaping the rim itself, within the shaping die Figure 1 cross-sectional view of the rim (represented in a simplified manner, without including all the details visible in its Figures 1 to 4 ). DETAILED DESCRIPTION

[0058] Figures 1 to 4 A cross-sectional view schematically shows the rim 10 of a bicycle wheel. The rim 10 is made of a composite material, for example a material comprising structural fibers incorporated in a polymer matrix. The structural fibers are selected from carbon fibers, glass fibers, boron fibers, aramid fibers, ceramic fibers or other fibers with suitable mechanical characteristics; different parts of the rim 10 can also be made of different fibers. The polymer matrix is obtained from any thermoplastic or thermosetting polymer material compatible with the selected fibers. In particular, a thermosetting matrix can be easily deformed in the uncured state and can be crosslinked by curing; the term "curing" here refers to the process of subjecting the uncured material to suitable pressure and temperature in order to cause crosslinking of the polymer matrix and thus solidify in a predetermined shape. On the other hand, a thermoplastic matrix reaches the desired hardness when subjected to injection molding.

[0059] The composite material for the rim 10 includes a plurality of layered structures and inserts, which are made integral with each other during the curing process to form a structurally single component. These layered structures and these inserts will be described below.

[0060] The rim 10 includes a radially outer peripheral channel 11 and a radially inner closed channel 21. The peripheral channel 11 includes an upper bridge 12 that extends between two opposite wings 13 and 14, the two opposite wings being adapted to hold a tire; the wings 13 and 14 are provided with respective rounded ends 15 and 16 that fold towards each other, thus forming an acute angle α equal to approximately 20° with respect to the direction A parallel to the axis of the rim 10. The closed channel 21 extends radially inwards from the upper bridge 12 and includes two side walls (or flanks) 23, 24, which are connected together by the upper bridge 12 and a lower bridge 25.

[0061] The peripheral channel 11 includes an inner layered structure 31 and a wound layered structure 32, wherein the inner layered structure 31 extends from the wing 13 through the entire upper bridge 12 to the wing 14. The wound layered structure 32 is wound around the inner layered structure 31 and closes on itself so as to completely surround the inner layered structure 31, as Figure 1 visible in Figure 2 and better visible in

[0062] The peripheral channel also includes two inner wing lamination structures 33 and 34 (visible in Figure 1 、 2 and in particular Figure 3 ), which are arranged between the inner lamination structure 31 and the winding lamination structure 32 at each of the wings 13 and 14 and also partly at the upper bridge 12.

[0063] The closed channel 21 includes a closed-channel lamination structure 35, which extends along the side walls 23 and 24, along the lower bridge 25 and at least partly along the upper bridge 12. The closed-channel lamination structure 35 includes an initial flap 35a and a final flap 35b, which are arranged at the upper bridge 12 and are arranged side by side with the winding lamination structure 32. The two flaps 35a and 35b are spaced apart from each other such that the winding lamination structure 32 (in particular its flap 32b which overlaps with the flap 32a) remains facing the interior of the closed channel 21. In this way, the closed-channel lamination structure 35 does not contribute to increasing the thickness of the upper bridge 12, where the winding lamination structure 32 has been thickened due to the overlap of the two flaps 32a and 32b; furthermore, during the manufacture of the rim 10 (which will be discussed below), the flaps 35a and 35b can slide more easily in the mold during shaping and before curing.

[0064] In Figure 6 the variant shown, the closed-channel lamination structure 135 has overlapping initial and final flaps 135a and 135b. In this way, the closed-channel lamination structure 135 closes on itself to form a completely box-shaped and thus particularly rigid structure.

[0065] The rim 10 also includes an outer lamination structure 36, which extends externally in the rim 10 from the wing 13 to the side wall 23, to the lower bridge 25, to the side wall 24 and up to the wing 14. The outer lamination structure 36 overlaps the winding lamination structure 32 at the wings 13 and 14 and covers the closed-channel lamination structure 35 at the closed channel 21.

[0066] The rim 10 also includes two outer wing lamination structures 37 and 38 (visible in Figure 1 、 2 and in particular Figure 3 ), each of the outer wing lamination structures 37 and 38 being arranged between the outer lamination structure 36 and the winding lamination structure 32 (at each of the wings 13 and 14) and the closed-channel lamination structure 35 (at the side walls 23 and 24 of the closed channel 21).

[0067] Furthermore, the rim 10 includes a lower-bridge lamination structure 39 (in Figure 1 and in particular in Figure 4As can be seen in the figure, the lower bridge delamination structure 39 extends at the lower bridge 25 and is arranged between the closed channel delamination structure 35 and the outer delamination structure 36.

[0068] In Figure 7 In the shown variant, the lower bridge delamination structure 239 overlaps with the closed channel delamination structure 35 inside the closed channel 21, that is, on the opposite side relative to the outer delamination structure 36.

[0069] The rim 10 further includes two circumferential inserts 41 and 42, which are arranged in two converging regions between the upper bridge 12, the wings 13 and 14, and the side walls 23 and 24. These circumferential inserts 41 and 42 (preferably manufactured according to the teachings of EP1506882B1) are formed by directionally structured fibers incorporated in the polymer material, and these directionally structured fibers are oriented in the circumferential direction of the rim 10. The circumferential inserts 41 and 42 are inserted into the structure of the rim 10, between the winding delamination structure 32 and the closed channel delamination structure 35, below the outer wing delamination structures 37 and 38, and below the outer delamination structure 36.

[0070] Each of the delamination structures 31 - 39 is made of one or more layers of structural fibers, preferably directionally structured fibers.

[0071] The peripheral channel 11 includes a pair of circumferential protrusions 51 and 52, and each of the pair of circumferential protrusions 51 and 52 has a surface inclined at an acute angle β with respect to the direction A parallel to the rotational axis of the rim 10. The angle β is slightly smaller than the inclination angle α of the ends 15 and 16 of the wings 13 and 14 by 0.5 - 4 degrees, preferably slightly smaller by about 2 degrees.

[0072] The protrusions 51 and 52 are formed together with the winding delamination structure 32 through corresponding grooves formed in the molding die; during molding, the polymer material of the winding delamination structure 32 fills these grooves and forms the protrusions 51 and 52. Given that the stress that the protrusions 51 and 52 have to bear is very limited, there is no need to pay attention to the structural fibers of the winding delamination structure 32 also entering into the said grooves during molding and thus being incorporated into the protrusions themselves. Alternatively, the grooves corresponding to the protrusions 51 and 52 of the die can be filled with a polymer material (especially a thermosetting resin).

[0073] The rim 10 can be made by one of the methods known in the art, for example, made using a radial die according to the teachings of EP1231077B2. Preferably, as shown in Figure 8 and Figure 9 shown, the rim 10 is made in the following manner.

[0074] First, a radial die 400 is provided, which is shaped in accordance with the contour of the rim 10. Thus, the die 400 (in a manner corresponding to the teachings of EP1231077B2) includes: a pair of radial inner shells 401 and 402, which are shaped to define the radial inner contour of the rim 10 (i.e., the radial inner contour of the lower bridge 25 and the radial inner contours of the sidewalls 23 and 24); a radial outer shell 403, which is provided with a central die insert 404 (shaped to define the outer contour of the peripheral channel 11) and two movable side die inserts 405 and 406 (shaped to define the contours of the flanges 13 and 14); the radial outer shell 403, the central die insert 404, and the movable side die inserts 405, 406 are all made in sectors, for example, three sectors of 120 degrees, so as to allow the rim to be removed once it is formed. The die 400 also includes an inflatable and removable pressing element 407, which is shaped to define the inner contour of the closed channel 21.

[0075] Individually, on the working plane, the layered structure is arranged in an uncured state to form the peripheral channel 11. The wound layered structure 32 is first laid on the working plane, then the inner layered structure 31 is overlapped, and then the inner flange layered structures 33 and 34 are overlapped; the inner layered structure 31 has the same length as the wound layered structure 32 (substantially equal to the circumference of the rim 10 to be manufactured), and a smaller width less than half of the width of the wound layered structure 32; the inner layered structure 31 and the inner flange layered structures 33, 34 are positioned to reach the same position in the width direction. Thus, the inner layered structure 31 and the inner flange layered structures 33 and 34 are in a flat state, where the wound layered structure 32 encloses on top, to fold two opposite flaps 32a and 32b on the inner layered structure 31 and overlap them with each other. In this way, the first assembly of the layered structure is arranged, which will form most of the peripheral channel 11.

[0076] Then, the pair of radial inner shells 401 and 402 are arranged such that they are joined together. Inside, the outer layered structure 36 is arranged, then the lower bridge layered structure 39 is arranged, then the unfolded closed channel layered structure 35 is arranged, and then the pressing element 407 is arranged; the closed channel layered structure 35 is then folded with its flaps 35a and 35b on the pressing element 407. At this time, the circumferential inserts 41, 42, and finally the above assembly are arranged in the die 400, where the layered structures 31 - 34 have been preformed and folded into a radially outward C shape.

[0077] Finally, the die 400 is closed, first placing the movable side die inserts 405 and 406, then placing the central die insert 404, and finally placing the radial outer shell 403. This achieves Figure 8The structure shown. It should be noted that the layered structures 32 and 31 that will form the wings 13 and 14 only partially (i.e., not completely) occupy the space between the shells 401, 402, 403 and the die inserts 405, 406.

[0078] Once the die 400 is closed, the pressing element 407 is activated (inflated) so as to apply pressure to the layered structure arranged in the die 400 from the inside to the outside. In particular, this pressure pushes the layered structure of the preform assembly (the wound layered structure 32 with the inner layered structure 31 and the inner wing layered structures 33, 34 inside), towards the end regions of the die 400 and compresses the material until the entire space between the shells 401, 402 and 403 and the movable side die inserts 405, 406 is occupied. In this step, the closed channel layered structure 35 follows the expansion of the pressing element 407 and is not particularly hindered since the flaps 35a and 35b do not overlap. Figure 9 The die is shown, and the pressing element 407 has been almost completely inflated. It should be noted that the layered structures 32 and 31 that will form the wings 13 and 14 now completely occupy the space between the shells 401, 402, 403 and the die inserts 405, 406.

[0079] Once the desired final shape is reached, the die 400 is subjected to curing, i.e., the die 400 is subjected to a predetermined pressure and temperature for a predetermined time in order to cause the setting of the polymeric material.

[0080] Once the curing is complete, the die 400 is opened and the die inserts 404, 405 and 406 are removed; the above-mentioned angles α and β facilitate this operation. Finally, the rim 10 is removed from the die 400.

[0081] The ends 15 and 16 of the wings 13 and 14 already have their final rounded shape without the need for further machining.

[0082] Figure 5 Different embodiments of the present invention are shown, which show a rim 310 similar to the rim 10, but the rim 310 has a simplified structure with a single channel.

[0083] The rim 310 includes a peripheral channel 311 that has an upper bridge 312 that extends between two opposite wings 313 and 314 adapted to hold a tire; the wings 313 and 314 are provided with corresponding rounded ends 315 and 316 that are folded towards each other so as to form an acute angle α equal to approximately 20° with respect to the direction B parallel to the axis of the rim 310.

[0084] The peripheral channel 311 includes an inner laminate structure 331 and a wound laminate structure 332, where the inner laminate structure 331 extends from the wing 313 through the entire upper bridge 312 to the wing 314. The wound laminate structure 332 is wound around the inner laminate structure 331 and closes on itself, thus completely surrounding the inner laminate structure 331. The wound laminate structure 332 includes an initial flap 332a and a final flap 332b, and the flaps 332a, 332b overlap each other at a radially inner position relative to the upper bridge 312 at the mid-plane N of the rim 310.

[0085] The peripheral channel further includes two inner wing laminate structures 333, 334, and the inner wing laminate structures 333, 334 are arranged between the inner laminate structure 331 and the wound laminate structure 332 at each of the wings 313, 314 and (partially) the upper bridge 312.

[0086] The rim 310 further includes an outer laminate structure 336, and the outer laminate structure 336 extends externally in the rim 310 from the wing 313 to the upper bridge 312 until the wing 314. The outer laminate structure 336 overlaps with the wound laminate structure 332 at the wings 313 and 314.

[0087] The rim 310 further includes two outer wing laminate structures 337 and 338, and each outer wing laminate structure is arranged between the outer laminate structure 336 and the wound laminate structure 332 at each of the wings 313 and 314.

[0088] The rim 10 further includes two circumferential inserts 341 and 342, and the two circumferential inserts 341 and 342 are arranged in two converging regions between the upper bridge 312 and the wings 313 and 314. These circumferential inserts 341 and 342 (exactly similar to the circumferential inserts 41 and 42) are formed by directional structural fibers incorporated in the polymer material and oriented in the circumferential direction of the rim 310. The circumferential inserts 34l and 342 are inserted into the structure of the rim 310 between the wound laminate structure 332 and the outer laminate structure 336, below the outer wing laminate structures 337 and 338.

[0089] The laminate structures 331 - 338 are made in a manner similar to the laminate structures 31 - 38, and each laminate structure has one or more layers of structural fibers, preferably directional structural fibers.

[0090] The peripheral channel 311 includes a pair of circumferential protrusions 351 and 352, which are exactly similar to the protrusions 51 and 52 of the rim 10. Each of the pair of circumferential protrusions 351 and 352 has a surface inclined at an acute angle β with respect to the direction B parallel to the rotation axis of the rim 310. With respect to the inclination angle α of the ends 315 and 316 of the wings 313 and 314, the angle β is slightly smaller by 0.5 - 4 degrees, preferably slightly smaller by about 2 degrees.

[0091] The rim 310 can be made by one of the methods known in the art, for example by means of a radial die according to the teaching of EP1231077B2. Preferably, the rim 310 is made in a manner similar to that of the rim 10; in fact, the method is the same, the difference being of course the omission of all the steps involving the closed channel and the lower bridge (which are not present here).

Claims

1. A bicycle rim, said bicycle rim being made of a plurality of layered structures of a composite material, each layered structure being formed by one or more structural fibers incorporated in a polymeric material, wherein, The rim includes a radially outer peripheral channel (11; 311), the radially outer peripheral channel (11; 311) includes an upper bridge (12; 312), the upper bridge (12; 312) extends between two opposite wings (13, 14; 313, 314) for holding a tire, and is characterized in that the peripheral channel (11; 311) includes an inner laminate structure (31; 331) and a wound laminate structure (32; 332), wherein the inner laminate structure (31; 331) extends from one of the wings to the other wing, the wound laminate structure (32; 332) is wound around the inner laminate structure (31; 331), and the wound laminate structure (32; 332) closes on itself by overlapping its initial flap (32a; 332a) with its final flap (32b; 332b) to completely surround the inner laminate structure (31; 331), and the inner laminate structure (31; 331) and the wound laminate structure (32; 332) are included in the plurality of laminate structures.

2. The rim according to claim 1, comprising a radially inner closed channel (21), said radially inner closed channel (21) being integral with said peripheral channel (11) in its radially inner position, wherein, The closed channel (21) is defined by two opposite side walls (23, 24), the two opposite side walls (23, 24) are connected together by the upper bridge (12) and in a radially inner position by a lower bridge (25), wherein the closed channel (21) includes a closed channel laminate structure (35; 135), the closed channel laminate structure (35; 135) extends along at least a part of the lower bridge (25), the side walls (23, 24), and the upper bridge (12), and the closed channel laminate structure (35; 135) is included in the plurality of laminate structures.

3. The rim according to claim 2, wherein, The closed channel laminate structure (35; 135) terminates at the peripheral channel (11) with an initial flap (35a; 135a) and a final flap (35b; 135b), wherein the initial flap and the final flap of the closed channel laminate structure (35; 135) are arranged side by side with the wound laminate structure (32).

4. The rim according to claim 3, wherein, The initial flap (35a) of the closed channel laminate structure is spaced apart from the final flap (35b) of the closed channel laminate structure so that the wound laminate structure (32) faces partially towards the interior of the closed channel (21).

5. The rim according to claim 3, wherein, The initial flap (135a) of the closed channel laminate structure overlaps the final flap (135b) of the closed channel laminate structure such that the interior of the closed channel (21) is completely surrounded by the closed channel laminate structure (35).

6. The rim according to claim 1, wherein, The peripheral channel (11; 311) includes two inner wing laminate structures (33, 34, 333, 334), each inner wing laminate structure overlapping at each of the wings (13, 14; 313, 314) and the inner laminate structure (31; 331), and together with the inner laminate structure (31; 331) being enclosed by the winding laminate structures (32, 332), the inner wing laminate structures (33, 34; 333, 334) being included in the plurality of laminate structures.

7. The rim according to claim 2, comprising an outer laminate structure (36) that extends externally from one of the wings (13) to one of the sidewalls (23), to the lower bridge (25), to the other sidewall (24), and to the other wing (14), wherein, The outer laminate structure (36) overlaps the closed channel laminate structure (35) at the closed channel (21), and covers the winding laminate structure (32) at the wings (13, 14), the outer laminate structure (36) being included in the plurality of laminate structures.

8. The rim according to claim 7, comprising two outer wing laminate structures (37, 38), each outer wing laminate structure (37, 38) overlapping the winding laminate structure (32) at each of the wings (13, 14), and covering the closed channel laminate structure (35) at the closed channel (21), located below the outer laminate structure (36), the outer wing laminate structures being included in the plurality of laminate structures.

9. The rim according to claim 7, comprising a lower bridge laminate structure (39; 239) at the lower bridge (25), the lower bridge laminate structure (39; 239) being included in the plurality of laminate structures.

10. The rim according to claim 9, wherein, The lower bridge laminate structure (39) is arranged between the outer laminate structure (36) and the closed channel laminate structure (35), or overlaps the closed channel laminate structure (35) on the opposite side relative to the outer laminate structure (36).

11. The rim according to claim 1, wherein, The respective ends (15, 16; 315, 316) of the wings (13, 14; 313, 314) are folded towards each other at a predetermined acute angle α with respect to the axial direction of the rim, and the peripheral channel (11; 311) includes a pair of circumferential protrusions (51, 52, 351, 352), the pair of circumferential protrusions (51, 52, 351, 352) having surfaces inclined at an acute angle β with respect to the axial direction of the rim, where α > β.

12. The rim according to claim 11, wherein, The predetermined acute angle α is equal to approximately 20°.

13. The rim according to claim 11, wherein, The difference α – β is between 0.5 degrees and 4 degrees.

14. The rim according to claim 13, wherein, The difference α – β is equal to approximately 2 degrees.

15. A method of manufacturing a bicycle rim (10; 310), the bicycle rim (10; 310) being made of a composite material based on structural fibers incorporated in a polymeric material, the rim (10; 310) including a radially outer peripheral channel (11; 311), the radially outer peripheral channel (11; 311) including an upper bridge (12; 312) extending between two opposite wings (13, 14; 313, 314) for holding a tire, the method comprising the following steps: a) Providing: a radial die (400) shaped according to the profile of the bicycle rim (10; 310); at least one pressing element (407); and at least one die insert (404, 405, 406) for forming an end region in the die (400), the end region being adapted to form the wings (13, 14; 313, 314); b) Laying a wound laminate structure (32; 332) of uncured composite material on a working plane, the composite material comprising structural fibers incorporated in a polymeric material; c) Laying an inner laminate structure (31; 331) of uncured composite material on the wound laminate structure (32; 332), the composite material comprising structural fibers incorporated in a polymeric material, the length of the inner laminate structure (31; 331) being equal to the length of the wound laminate structure (32; 332), and the width of the inner laminate structure (31; 331) being less than half of the width of the wound laminate structure (32; 332); d) Folding two opposite flaps (32a, 32b; 332a, 332b) of the wound laminate structure (32; 332) in the width direction over the inner laminate structure (31; 331) so that the two opposite flaps overlap each other and the wound laminate structure (32; 332) completely surrounds the inner laminate structure (31; 331); e) Arranging the pressing element (407) and the wound laminate structure (32; 332) in the die (400), wherein the inner laminate structure (31; 331) is included and folded in a C-shaped configuration over the pressing element (407); f) Positioning the at least one die insert (404, 405, 406) in the die (400) such that the wound laminate structure (32; 332) enclosing the inner laminate structure (31; 331) reaches the end region of the die (400); g) Closing the die (400) and applying pressure with the pressing element (407) on the wound laminate structure (32; 332) and the inner laminate structure (31; 331) so as to cause the polymeric material to flow and move the structural fibers in the direction of the end region of the die (400) until the entire space between the die (400) and the at least one die insert (404, 405, 406) is occupied; h) Subjecting the die (400) to a pressure and temperature profile to cause the setting of the polymeric material; i) Opening the die (400); j) Removing the at least one die insert (404, 405, 406); k) Removing the molded bicycle rim (10; 310).

16. The method according to claim 15, further comprising the steps of: a1) Provide two circumferential inserts (41, 42; 341, 342), each of which is formed by directional structural fibers incorporated in a polymeric material, and the directional structural fibers are oriented in the circumferential direction; f1) In the mold (400), position the circumferential inserts (41, 42; 341, 342) at the convergence region of the upper bridge (12; 312) and one of the wings (13, 14; 313, 314), between the wound laminate structure (32; 332) enclosing the inner laminate structure (31; 331) and the pressing element (407).

17. The method according to claim 15, further comprising the following steps: d1) Provide a closed-channel laminate structure (35), and the closed-channel laminate structure (35) is wound around the pressing element (407).

Images