Fiber-reinforced composite tubular shaft and its manufacture

Abstract

1. An elongated tubular shaft constructed of a fiber reinforced resin matrix composite material, the shaft comprising an elongated tubular body comprising a stack of wound layers, each wound layer comprising a fiber reinforcement in a resin matrix, the elongated tubular body having an elongated inner circumferential surface having a first surface portion having a non-cylindrical geometry along at least a portion of the length of the elongated tubular body, and an elongated outer circumferential surface, the stack of wound layers of fiber reinforcement comprising a fiber layer, the fiber layer comprising at least one ply of fiber reinforcement, the fiber layer forming the stack of wound layers. a first surface portion of the elongated tubular shaft, the first surface portion of the elongated tubular shaft being helically wound around the longitudinal axis of the elongated tubular body, each wound layer being parallel to the longitudinal axis, the fiber layers having a non-constant width that varies non-linearly with changes in radius of the elongated inner circumferential surface within the portion, the fiber reinforcement comprising fibers along the length of the elongated tubular body that are constantly oriented relative to a cylindrical coordinate system about the longitudinal axis of the elongated tubular body, the fiber orientation of any portion being independent of the geometry of the elongated inner and outer circumferential surfaces of that portion.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to a method for manufacturing an elongated tubular shaft constructed from a fiber reinforced resin matrix composite material.The present invention also relates to an elongated tubular shaft constructed from a fiber reinforced resin matrix composite material. [Background technology]

[0002] It is generally known in the field of composites that composite tubes, otherwise referred to as tubular shafts, can be manufactured by a method in which a tape of preform material is wound, e.g., spirally, around a metal mandrel. Pressure is then applied to this composite structure using a compression system in a molding process to solidify the thermoset and / or thermoplastic resin matrix, and the mandrel is then removed from the molded tubular product.

[0003] Alternatively, the preform material may be in the form of a sheet wound around an axis of rotation aligned with the longitudinal axis of the mandrel. In particular, such composite tubes are commonly made by a roll-wrapping process. The sheet may be oriented perpendicular or at an oblique angle to the longitudinal axis of the mandrel. Roll-wrapping involves wrapping around a mandrel individual preforms or individual layers of preform material having the same or different length as the tube and a width corresponding to a specific number of turns around the mandrel.

[0004] The preform material may comprise a fiber layer of dry fiber material, i.e., fiber material that does not contain the resin material, e.g., thermoset and / or thermoplastic resin material, that will subsequently be used to form the resin matrix of the composite material. After the fiber layer is wound as described above, the fiber material may be coated, impregnated, or infused with a resin material before or during the molding step. Alternatively, the preform material may comprise a prepreg material. Such prepreg materials are widely used in the manufacture of composite parts and structures. Prepreg materials are a combination of a thermoset and / or thermoplastic resin matrix and a fiber reinforcement, with the resin at least partially, and typically completely, impregnating the fiber reinforcement.

[0005] The winding of a preform or prepreg around a mandrel having a cylindrical surface other than that given by a circular cross section of a given radius extending along the entire length of the mandrel, either helically using a thin tape or by roll wrapping a sheet aligned perpendicular or at an angle to the mandrel, can present significant technical problems.

[0006] The first technical problem is that as the cross section of the mandrel varies along its length, the prepreg may become skewed relative to the desired wrapping direction, which can result in wrinkles and fiber misalignment in the wrapped elongated tube, significantly degrading the mechanical performance and appearance of the resulting elongated tubular shaft constructed from a fiber-reinforced resin matrix composite formed with the prepreg.

[0007] In high performance composite products, it is essential that the fiber orientation and alignment along the entire length of the tubular shaft be maintained within desired close tolerances to achieve high mechanical properties.

[0008] Fiber mismatch is particularly problematic in the manufacture of non-cylindrical tubing, especially when product uniformity and consistency are important performance parameters.

[0009] Another problem in the manufacture of non-cylindrical tubes with complex tube geometries is that the fiber layers can be inadvertently bent, twisted, or folded, resulting in the undesirable formation of wrinkles in the preform layers, which appear as misaligned or bent fibers, or even voids, in the final molded composite product.

[0010] Additionally, wrinkles and fiber mismatch can result in inconsistent performance between multiple tubular products. Known manufacturing methods can encounter significant manufacturing problems in achieving these desired properties.

[0011] A second technical challenge is adapting to variations in the mandrel's geometry along its length, which can require a high degree of human intervention during the manufacturing process and result in a reduced level of automation, increasing manufacturing costs and complexity and reducing the consistency and uniformity of multiple tubular products.

[0012] A third technical problem is that such known processes can result in high levels of prepreg waste, either as a result of prepreg tapes or sheets needing to be individually cut or trimmed to remove excess material from the mandrel, or as a result of excess material needing to be removed from the tubular product following the forming step, or as a result of the produced tubular product being rejected because it does not meet the desired quality.

[0013] Additionally, it is known to manufacture sporting goods such as golf club shafts, fishing rods, and rackets from fiber-reinforced resin matrix composites, particularly carbon fiber composites. However, long tubular shafts of carbon fiber composites tend to suffer from non-uniform wall thicknesses that result in non-uniform properties, particularly undesirable variations in bending stiffness along the shaft, especially when subjected to bending forces at different rotational orientations about the axis of the shaft. Tubular sporting goods often need to incorporate controlled, variable thicknesses to locally control the stiffness of the goods; however, reliably and repeatably automating the manufacturing process to produce such controlled, variable thicknesses with a high degree of uniformity and consistency across multiple products is difficult.

[0014] British Patent Application No. 2177062 discloses the manufacture of composite parts with prepreg tape wound on a frustoconical mandrel. The tape is wound so that each successive wrap of tape overlaps the previous wrap of tape by approximately 50% of the tape width. Tape width (W) is defined by the formula W = nt / tan α, where t is the tape thickness, α is the conical angle of the mandrel in degrees, and n is the number of tape layers or tapes wound in one wrap, such that as n increases, tape width increases proportionally. While the method of winding filaments on a frustoconical surface is said to avoid distortion that occurs when tapes are wound edge-to-edge without overlapping and to avoid large gaps in the wound material, this method nevertheless cannot guarantee precise filament alignment for tubular parts of significant length or for a significant number of wraps of filament. Therefore, this manufacturing method suffers from the problem that as the diameter of the mandrel increases, the fibers in the prepreg, and therefore in the final composite, gradually become misaligned, resulting in a decrease in the mechanical properties of the part and in variations in mechanical properties along the length of the part. Furthermore, along the length of the part, the angle of any fiber relative to the longitudinal axis of the mandrel, and therefore the part, changes, causing the fibers to gradually become misaligned or twisted relative to the longitudinal axis as the diameter of the mandrel and part increases. In pre-wound prepregs, the fiber orientation may always be linear and precisely aligned along the desired axis within the prepreg; however, in the final wound part, the fiber orientation may not be consistently oriented or precisely aligned along the desired axis within the part. Furthermore, there is no disclosure of how to accurately manufacture complex shapes other than geometric frusto-conical tubes.

[0015] U.S. Patent Application Publication No. 2011 / 0097526 discloses a woven fiber preform for forming a fiber-reinforced composite incorporating the preform. The woven preform includes a plurality of warp and weft yarns or warp and weft fibers interwoven to form a continuous spiral fabric. The spiral fabric may take the shape of an Archimedes spiral. The weft yarns of the preform may have uniform or variable pick spacing or uniform or variable angular separation. The Archimedes spiral spiral fabric may be assembled or wound to form a conical shell structure, which may be part of a spinner or blower. This disclosure suffers from the problem that the preform has a complex, specific spiral geometry and can only be used to create the specific geometry of the conical shell. Also, if the weft yarns have uniform spacing and uniform angular separation, the yarns will be misaligned in the conical shell; however, if the weft yarns have variable spacing and / or variable angular separation, the yarns may be conically aligned in the conical shell. However, the preforms are highly complex, with variable fiber structures woven together, and each preform can only be used to create a specific geometric shape. There is no disclosure of how to actually create such highly complex fabrics for the preforms. Furthermore, there is no disclosure of how to accurately manufacture complex shapes other than geometric conical shells.

[0016] U.S. Patent Application Publication No. 2003 / 0056846 discloses a length of fabric having a variable width for forming tubes of various diameters. This disclosure suffers from the problem that each tube has a specific arrangement of warp and weft fibers that can only be used to create a specific geometry of the variable diameter tube. Fabrics with variable fiber structures are very complex to weave. There is no disclosure of a method for controlling the outer geometry of the tube.

[0017] WO 2004 / 067264 discloses a method for depositing a tilted fiber layer from a continuous wound band onto a support that may have a variable diameter. This disclosure suffers from the problem that the method is highly complex. Furthermore, there is no disclosure of how to accurately produce complex shapes other than cylindrical or frustoconical tubular shapes from the tilted fiber layer. There is also no disclosure of a method for providing longitudinally oriented fibers along a significant length of the tube, or especially along the entire length. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] UK Patent Application No. 2177062 [Patent Document 2] U.S. Patent Application No. 2011 / 0097526 [Patent Document 3] U.S. Patent Application No. 2003 / 0056846 [Patent Document 4] International Publication No. 2004 / 067264 Pamphlet Summary of the Invention [Problem to be solved by the invention]

[0019] It is therefore an object of the present invention to at least partially overcome one or more of the above-mentioned problems encountered with known methods of manufacturing composite tubular shafts.

[0020] Accordingly, the present invention particularly aims to provide an improved method for manufacturing elongated tubular shafts composed of fiber reinforced resin matrix composite materials, which allows the elongated tubular shafts to exhibit high quality mechanical properties even when the shafts may have non-uniform thickness, cross-section, and / or external or internal shape and dimensions along the length of the shaft.

[0021] Most specifically, the present invention aims to provide an improved method for manufacturing elongated tubular shafts composed of fiber reinforced resin matrix composite material, which method can be automated to reliably, consistently, and repeatably provide tubular shafts having uniformly controlled wall thickness about the axis of the shaft and precise control of fiber alignment about the axis of the shaft, in a low-cost manufacturing process, which can thus provide that the shafts exhibit consistent flexure characteristics about the axis of the shaft.

[0022] It is a further object of the present invention to provide an improved method for manufacturing elongated tubular shafts composed of fiber reinforced resin matrix composites, preferably using automated or automatable manufacturing methods, which allows for the consistent production of complex tubular geometries, thereby improving the designability of the final tubular product.

[0023] Finally, the present invention also aims to provide an improved elongated tubular shaft constructed of a fiber-reinforced resin matrix composite material having a non-cylindrical inner surface and cross-section. In particular, the present invention also aims to provide an improved elongated tubular shaft constructed of a fiber-reinforced resin matrix composite material that can exhibit highly accurate and consistent fiber alignment about the axis of the shaft, and thus can provide high quality mechanical properties along the length of the shaft, even when the shaft incorporates complex tubular geometries. [Means for solving the problem]

[0024] The present invention provides a method for manufacturing a long tubular shaft composed of a fiber reinforced resin matrix composite material as set forth in claim 1. The method of a preferred embodiment of the present invention provides that each fiber is uniformly oriented relative to a cylindrical coordinate system about the axis of rotation of the mandrel.

[0025] Preferred features of the sports equipment are defined in dependent claims 2 to 26.

[0026] The present invention also provides a long tubular shaft made of the fiber reinforced resin matrix composite material of claim 27.

[0027] Preferred features of the elongate tubular shaft are defined in dependent claims 28 to 41.

[0028] A preferred embodiment of the present invention can provide a method for manufacturing elongated tubular shafts on a mandrel where the cross section of the mandrel varies along the length of the mandrel, thereby having a "complex" shape.

[0029] Despite this complex mandrel geometry, the orientation of the fibers can remain constant within a cylindrical coordinate system associated with the rotational axis of the mandrel, even when using "long" fibers having lengths of at least 50 mm, which "long" fibers may have lengths of more than 10 meters, and at least some of these fibers can extend individually along the entire length of the elongated tubular shaft.

[0030] This technical effect and advantage for achieving highly consistent and precise fiber orientation and alignment of such long fibers within a long tubular shaft formed from one or more wound preform layers is believed by the inventors to be unique in composites technology, enabling improved performance of fiber-reinforced composite structures in applications where product consistency is a critical design and performance factor. Furthermore, by providing highly aligned "long" fibers having lengths of at least 50 mm, and even lengths greater than 10 meters, the mechanical properties of the composite, particularly strength and toughness, are improved.

[0031] The geometry of the inner tube can have a complex shape and can incorporate any combination of the following geometric or structural features: a cone with increasing and / or decreasing and / or neutral slope, one or more bumps or protrusions, one or more ledges, one or more recessed grooves, or one or more indentations, a cross section that can be of any shape and vary along the length of the tube. Correspondingly, the geometry of the outer tube can have a complex shape and can incorporate any combination of the following geometric or structural features: a cone with increasing and / or decreasing and / or neutral slope, one or more bumps or protrusions, one or more ledges, one or more recessed grooves, or one or more indentations.

[0032] A preferred embodiment of the present invention can provide a method for manufacturing elongated tubular shafts on a mandrel, where the shafts have complex tubular geometries and can be formed to near net shape, and this can be achieved in a single winding and forming operation in a fully automated manner with very little waste, thereby improving productivity and repeatability while reducing waste.

[0033] Additionally, preferred embodiments of the present invention can provide a method for manufacturing elongated tubular shafts on a mandrel that has the ability to independently control the geometry of the inner and outer tubes, thereby increasing the design space in a general manner for manufacturing tubular shafts.

[0034] A preferred embodiment of the present invention provides a method for manufacturing a long tubular shaft in which the preform is not skewed relative to the desired winding direction, even when the mandrel cross-section varies along its length. Thus, wrinkles and fiber misalignment can be avoided or minimized within the wound long tube. The resulting long tubular shaft, constructed of a fiber-reinforced resin matrix composite, can reliably, consistently, and repeatably exhibit high-quality mechanical performance and appearance. To achieve high mechanical properties, fiber orientation and alignment along the entire length of the tubular shaft can be maintained within desired close tolerances.

[0035] Preferred embodiments of the present invention can also provide a high degree of automation and low or no human intervention during the manufacturing process to accommodate variations in the mandrel geometry along its length, particularly when manufacturing tubing having complex geometries. Compared to known manufacturing methods, manufacturing costs and complexity can be reduced, uniformity of multiple tubular products can be improved, and manufacturing times can be reduced, particularly when manufacturing tubing having complex geometries.

[0036] Preferred embodiments of the present invention can also avoid or minimize preform waste depending on the complexity of the elongated tubular shaft geometry. In preferred embodiments of the present invention, the shape and configuration of each preform to be wound around the mandrel is pre-calculated prior to the winding step based on the combined parameters of preform layer thickness, mandrel geometry, and tube geometry to provide a complex preform geometry adapted to be wound perpendicular to the complex mandrel geometry to form the complex tube geometry. Pre-calculating such complex preform shapes prior to the winding step allows for automated wrapping and minimized waste, as the preform layers are cut, subsequently wound, and then formed into a "near net shape" that avoids or minimizes waste during or after the winding or forming step. Winding to form a preform tube that approximates the final product shape can result in reduced waste and can reduce or avoid the time required for finishing processes, such as the retrieval process, to finish the final formed tubular shaft.

[0037] In summary, preferred embodiments of the present invention can also provide a highly flexible, automated manufacturing method for creating complex tubular shafts composed of composite materials. As a result, preferred embodiments of the present invention further provide tubular shafts composed of composite materials that can have complex geometries on the one hand and highly consistent and precisely aligned fibers on the other hand, along with associated high mechanical properties.

[0038] Tubular shafts produced by preferred embodiments of the present invention can be used to manufacture sporting goods such as golf club shafts, fishing rods, rackets, masts for boats and windsurfing boards, etc., or any other high quality composite tubular products from fiber reinforced resin matrix composites, particularly glass or carbon fiber composites.

[0039] Other features or advantages of the present invention will become more apparent from the following detailed description of some non-limiting embodiments of the invention, as illustrated in the accompanying drawings. [Brief explanation of the drawings]

[0040] [Figure 1] 1 is a schematic plan view of a preform layer suitable for use in a method of manufacturing an elongated tubular shaft constructed of fiber reinforced resin matrix composite material, in accordance with one embodiment of the present invention; FIG. [Figure 2a] 1A and 1B schematically illustrate a plan view of a preform layer relative to a Cartesian coordinate system, according to one embodiment of the present invention. [Figure 2b] 1A and 1B show schematic cross-sectional views of preform layers after being wrapped around a mandrel, according to one embodiment of the present invention; [Figure 3] 1 is a graph detailing a cross section through the layer structure of a preform layer wound on a mandrel, according to one embodiment of the present invention; [Figure 4] 4 is a graph detailing the preform layer plan used in FIG. 3 showing calculations of the shape and dimensions of the preform wound on the mandrel, according to one embodiment of the present invention. [Figure 5a] 5A and 5B show schematic top views of preform layers relative to a Cartesian coordinate system according to a second embodiment of the present invention; [Figure 5b] 4 shows a schematic cross-sectional view of a preform layer after being wound around a mandrel according to a second embodiment of the present invention; [Figure 6a] 10A and 10B show schematic top views of preform layers relative to a Cartesian coordinate system according to a third embodiment of the present invention; [Figure 6b] 10 shows a schematic cross-sectional view of a preform layer after being wound around a mandrel according to a third embodiment of the present invention. [Figure 7a] 10A and 10B show schematic top views of preform layers relative to a Cartesian coordinate system according to a fourth embodiment of the present invention; [Figure 7b] 10 shows a schematic cross-sectional view of a preform layer after being wound around a mandrel according to a fourth embodiment of the present invention. [Figure 8a] 10A and 10B show schematic top views of preform layers relative to a Cartesian coordinate system according to a fifth embodiment of the present invention; [Figure 8b] 10 shows a schematic cross-sectional view of a preform layer after being wound around a mandrel according to a fifth embodiment of the present invention. [Figure 9a] 10A and 10B show schematic top views of preform layers relative to a Cartesian coordinate system according to a sixth embodiment of the present invention; [Figure 9b] 10 shows a schematic cross-sectional view of a preform layer after being wound around a mandrel according to a sixth embodiment of the present invention. [Figure 10a] 13A and 13B show schematic top views of preform layers relative to a Cartesian coordinate system according to a seventh embodiment of the present invention; [Figure 10b] 13 shows a schematic cross-sectional view of a preform layer after being wound around a mandrel according to a seventh embodiment of the present invention. [Figure 11a] 13A and 13B show schematic top views of preform layers relative to a Cartesian coordinate system according to an eighth embodiment of the present invention; [Figure 11b] 13 shows a schematic cross-sectional view of a preform layer after being wound around a mandrel according to an eighth embodiment of the present invention. [Figure 12a] 13A and 13B show schematic top views of preform layers relative to a Cartesian coordinate system according to a ninth embodiment of the present invention; [Figure 12b] 13A and 13B show schematic cross-sectional views of preform layers after being wound around a mandrel according to a ninth embodiment of the present invention; [Figure 13a] 13A and 13B show schematic top views of preform layers relative to a Cartesian coordinate system according to a tenth embodiment of the present invention; [Figure 13b] 13A and 13B show schematic cross-sectional views of preform layers after being wound around a mandrel according to a tenth embodiment of the present invention; [Figure 14] 10A and 10B show schematic longitudinal cross-sections through portions of elongated tubular shafts constructed from fiber reinforced resin matrix composite material according to further embodiments of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0041] 1, 2a, and 2b show an example of a flexible preform layer 2 suitable for use in a method of manufacturing a long tubular shaft according to one embodiment of the present invention. The preform layer 2 is flexible, meaning that it can be rotationally wound around a mandrel to form a desired tubular shape, as described later in this specification. The flexible preform layer 2 comprises at least one ply 4 of fiber reinforcement 6. The preform layer 2 has a front major surface 10. Preferably, the preform layer 2 has a constant thickness. However, in other embodiments, the thickness may optionally vary in a controlled manner, for example, the thickness may vary linearly along the length of the preform layer 2. The thickness of the preform layer 2 is preferably in the range of 0.015 to 5 mm, optionally in the range of 0.1 to 2 mm.

[0042] The preform layer 2 has spaced apart first and second end portions 12, 14 and spaced apart inner and outer edges 16, 18. The inner and outer edges 16, 18 extend from the first end portion 12 toward the second end portion 14.

[0043] In accordance with the present invention, when the preform layer 2 is in a planar configuration, as shown in FIG. 1, at least the inner edge 16 is non-linear, and the spacing between the inner and outer edges 16, 18 varies along the length of the preform layer 2 extending between the first and second end portions 12, 14.

[0044] Thus, there is a non-linear relationship between the geometry and dimensions of the inner edge 16 of the preform layer 2 and the length of the preform layer 2 between the first and second end portions 12, 14. Correspondingly, there is a non-linear relationship between the spacing between the inner and outer edges 16, 18 and the length of the preform layer 2 between the first and second end portions 12, 14. As a result, when the preform layer 2 is wrapped around a non-cylindrical mandrel as described below, there is a non-linear relationship between the location of the inner edge 16 and the spacing between the inner and outer edges 16, 18, on the one hand, and between the location of the preform layer 2 along the length of the mandrel and the cumulative number of revolutions of the preform layer 2 along the length of the mandrel, specifically in a direction extending along the longitudinal axis of the mandrel, on the other hand.

[0045] In the embodiment of FIG. 1 , the first and second end portions 12, 14 each have linear ends, which are parallel to one another. The inner and outer edges 16, 18 each have curved edges. The inner edge 16 is convexly curved, and the outer edge 18 is concavely curved. As a result, in this embodiment, the preform layer 2 is shaped and dimensioned so that at least a portion of the inner edge 16 is curved, preferably convexly curved, when the preform layer 2 is in a planar configuration. However, in other embodiments, the inner edge 16 and the outer edge 18 may have different geometries, e.g., the inner edge 16 may be concavely curved and / or the outer edge 18 may be convexly curved.

[0046] As will be described below, the inner and outer edges 16, 18 have different curvatures and are not parallel to each other. The shape and configuration of each of the inner and outer edges 16, 18 is determined based on an analysis of the geometry of the mandrel around which the flexible preform layer 2 is wrapped to form the elongated tubular shaft, the thickness of the preform layer 2, and the shape and dimensions of the elongated tubular shaft.

[0047] The fiber reinforcement 6 can have any fiber configuration and may comprise woven or nonwoven fibers, for example in the form of unidirectional (UD) fibers, spread tow fibers, stitched fabric, knitted fabric, or braided fabric. The fiber reinforcement 6 may comprise multiple fibers of the same or different orientations. The fiber reinforcement 6 may comprise a single fiber ply or may comprise a stack of multiple fiber plies, the plies having the same or different fiber configurations.

[0048] When there are multiple plies, the entire preform layer 2 has a shape and dimensions that define a front major surface 10, first and second end portions 12, 14, and inner and outer edges 16, 18, although each ply may optionally have a different shape and dimensions compared to any other ply. Additionally, each ply may comprise a combination of two or more ply portions positioned adjacent to one another. The preform layer 2, or one or more plies within the plies of the preform layer 2, may include at least one hole, the one or more holes being surrounded by the preform layer 2.

[0049] The fibers of the fiber reinforcement 6 may comprise any natural and / or synthetic fibers. Typically, the fiber reinforcement 6 comprises glass, carbon, and / or aramid fibers, or cotton or jute fibers.

[0050] Preform layer 2 may comprise dry fiber reinforcement 6, i.e., fiber material that does not contain the resin material, e.g., thermoset and / or thermoplastic resin material, that will later be used to form the resin matrix of the composite. After preform layer 2 is wound as described below, dry fiber reinforcement 6 may be coated, impregnated, or infused with a resin material before or during the molding step. For example, liquid resin may be infused into dry fiber reinforcement 6 before or during the molding step. In another embodiment, an interposed solid resin layer may be deposited adjacent to dry fiber reinforcement 6 before or during the molding step. Other techniques for combining fibers and resin to form a fiber-reinforced resin matrix composite will be apparent to those skilled in the art.

[0051] Alternatively, the preform layer 2 may comprise a prepreg material that is at least partially, and optionally completely, impregnated with resin.

[0052] Resin 8 may be a thermoplastic or thermosetting resin. Any thermoplastic or thermosetting resin known to be suitable for use in the manufacture of fiber preforms may be used. Typically, a thermosetting resin such as an epoxy resin is used in conjunction with glass and / or carbon fibers in fiber reinforcement 6. When a thermosetting resin is used, preform layer 2 may comprise a prepreg in which fiber reinforcement 6 is fully impregnated with resin. In some embodiments, a single preform layer may be provided with different regions incorporating different resins, which may comprise a mixture of thermoplastic and / or thermosetting resins.

[0053] In an alternative embodiment of the present invention, the preform layer 2 can comprise a dry fiber reinforcement layer and a resin layer composed of a thermosetting or thermoplastic resin, with the preform layer and resin layer being stacked on top of each other. In a further embodiment of the present invention, the resin of the preform layer 2 composed of a thermosetting or thermoplastic resin can be partially or fully pre-cured before the subsequent winding step, as described below. In another embodiment of the present invention, the preform layer 2 can comprise a core material (not shown) and / or an adhesive material (not shown) on top of the preform layer 2 or the fiber reinforcement 6. The core material can comprise a layer of a cellular material, such as a cellular foam typically composed of a polymer such as a polyolefin or polyester, or a honeycomb material. Once the core material is provided, it is sandwiched between opposing layers of fiber reinforcement after the winding step into the final elongated tubular shaft manufactured according to the present invention.

[0054] The method of the present invention, as also shown in Figure 1, provides an elongated mandrel 20. The mandrel 20 may be comprised of a single piece or multiple pieces connected or assembled together. The mandrel 20 is typically comprised of a metal such as steel, but may alternatively be comprised of a composite material such as a fiber-reinforced resin matrix composite.

[0055] The mandrel 20 has a longitudinal axis LL and first and second opposing ends 22, 24 spaced apart from one another along the longitudinal axis LL. The mandrel 20 has an outer circumferential surface 26 that is non-cylindrical along at least a portion of the length of the mandrel 20 extending along the longitudinal axis LL. In the embodiment of FIG. 1, the non-cylindrical outer circumferential surface 26 is frusto-conical. However, the mandrel 20 can have any desired cross-sectional shape and dimensions, and in addition, the cross-sectional shape and dimensions may vary along the length of the mandrel. The mandrel outer surface 26 can have a complex shape and can incorporate any combination of the following geometric or structural features: a cone with increasing and / or decreasing and / or neutral slopes, one or more bumps or protrusions, one or more ledges, one or more recessed grooves, or one or more depressions, a cross-section of any shape that may vary along the length of the mandrel 20.

[0056] The present invention pre-shapes the pre-form layers according to the shape and dimensions of the mandrel and the final elongated tube so that after the pre-form layers are wound around the mandrel by rotation about the mandrel's longitudinal axis, the desired elongated tube is produced regardless of the particular individual geometry of the mandrel. Thus, this pre-shaping of the pre-form layers allows for the use of a wide variety of different mandrel geometries and the production of a similarly wide variety of elongated tube geometries.

[0057] As described below with reference to various embodiments of the present invention, the first and second end portions 12, 14 and inner and outer edges 16, 18 of the preform layer 2 may be provided with a variety of different shapes and sizes to allow the preform layer 2 to be wound around a variety of different mandrel shapes and sizes to produce elongated tubes of a variety of different shapes and sizes. A common feature in these embodiments is that the preform layer, and particularly at least the inner edge of the preform layer that contacts the outer peripheral surface of the mandrel during winding, is pre-shaped to control winding onto the respective mandrel.

[0058] To produce an elongate tubular shaft, the first end portion 12 of the preform layer 2 is positioned adjacent the first end 22 of the mandrel 20 in a starting configuration. In the starting configuration, the inner edge 16 is oriented toward the mandrel 20 and the outer edge 18 is oriented away from the mandrel 20.

[0059] The preform layer 2 is then wrapped around the mandrel 20 so that the outer peripheral surface 26 of the mandrel 20 is gradually covered by the wrapped preform layer 2 to form an elongated tube 28 .

[0060] During this winding step, the mandrel 20 and the preform layer 2 are rotated relative to one another about a rotation axis RR along the longitudinal axis LL of the mandrel 20. Typically, the mandrel 20 is rotated about the rotation axis RR to wind the preform layer 2 onto the mandrel 20, and the preform layer 2 remains rotationally stationary. Alternatively, the mandrel 20 remains rotationally stationary, and the preform layer 2 is rotated about the rotation axis RR to wind the preform layer 2 onto the mandrel 20.

[0061] During this winding step, the preform layer 2 continues to be fed onto the mandrel 20 along a feed path 32 perpendicular to the longitudinal axis LL of the mandrel 20 and therefore perpendicular to the rotation axis RR, from the first end portion 12 to the second end portion 14 of the preform layer 2.

[0062] The front major surface 10 is rotationally wrapped so as to be in surface contact with the outer circumferential surface 26. After the first wrapping rotation, the front major surface 10 preferably at least partially overlaps the previously wrapped portion of the preform layer 2 on the mandrel 20. As a result of the wrapping step, the inner edge 16 contacts the outer circumferential surface 26 of the mandrel 20 within the elongated tube 28, and the outer edge 18 is disposed on the outer circumferential surface 30 of the elongated tube 28.

[0063] Specifically, the inner edge 16 of the preform layer 2 is shaped and sized so that the inner edge 16 continuously conforms to the outer peripheral surface 26 of the mandrel 20 during the winding step, such that, as shown in FIG. 3, the elongated tube 28 comprises a plurality of winding layers 34 that form a spiral 42 about the longitudinal axis LL, with each winding layer 34 being uniformly oriented relative to a cylindrical coordinate system about the longitudinal axis LL.

[0064] Preferably, during the winding step, contact between at least a portion of the inner edge 16 and an area of ​​the outer peripheral surface 26 of the non-cylindrical mandrel 20 along at least a portion of the length of the elongated tube 28 at its inner surface 29 forms a continuous inner spiral line HL1, which extends along multiple (i.e., at least two) winding layers 34, for example at least ten winding layers 34, that coincide with the outer peripheral surface 26 of the mandrel 20.

[0065] As a result of the particular geometry of the curved inner edge 16 in combination with the generally frustoconical peripheral surface 26 of the mandrel 20 having a constant inclination angle relative to the longitudinal axis LL, the continuous inner helical line HL1 has a uniform pitch between successive helical revolutions of the winding layer 34. However, in alternative embodiments having an irregular, non-cylindrical surface of the mandrel, for example as described below, the pitch between successive helical revolutions of the winding layer may be variable and non-linear.

[0066] In one embodiment, at least a portion of the outer edge 18 forms a continuous outer spiral line HL2 on the outer surface 30 of the elongated tube 28 that is equidistant from the continuous inner spiral line HL1 along multiple winding layers 34 such that the elongated tube 28 has a constant thickness along at least that portion of the length of the elongated tube 28.

[0067] Because the preform layer 2 is placed on the mandrel in a specific orientation and wrapped around the longitudinal axis LL of the mandrel 20, which is also the longitudinal axis of the elongated tube 28, the orientation of the fiber reinforcement in the elongated tube 28 can be controlled by providing an initial orientation of the fiber reinforcement in the starting configuration.

[0068] In one exemplary embodiment, the fiber reinforcement comprises structural fibers, e.g., structural fibers contained in unidirectional (UD) fiber plies, which are aligned parallel to the longitudinal axis LL during the laying step and maintained at a constant orientation relative to a cylindrical coordinate system about the longitudinal axis LL during the winding step.

[0069] In a preferred embodiment of the present invention, the preform layer 2 is shaped and dimensioned so that when the preform layer 2 is wound around the mandrel 20 around an axis of rotation that coincides with the longitudinal axis LL of the mandrel 20 and the preform layer 2 is continuously fed along a feed path 32 that is perpendicular to the longitudinal axis LL of the mandrel 20, each winding rotation of the preform layer 2 around the mandrel 20, except for the first winding rotation, at least partially covers the previous winding rotation, and in some winding rotations, completely covers it.

[0070] However, in some embodiments of the present invention, the preform layer 2 may be shaped and dimensioned so that when the preform layer 2 is wrapped around the mandrel 20 around an axis of rotation that coincides with the longitudinal axis LL of the mandrel 20, at least some of the wrapping rotations of the preform layer 2 around the mandrel 20, excluding the first wrapping rotation, may be adjacent to or spaced apart from the immediately preceding wrapping rotation.

[0071] One or more preform layers may be comprised of two or more preform parts adjacent to or spaced apart from one another along the length of the mandrel. Multiple preform parts may be wound sequentially or at least partially simultaneously. Multiple preform parts may be comprised of the same or different preform compositions, e.g., the same or different fabrics and / or resins and / or orientations.

[0072] After the preform layer 2 is completely wound onto the mandrel 20, in some preferred embodiments of the present invention, a second preform layer (not shown) may be wound correspondingly on top of the first preform layer 2. Optionally, the second preform layer may be wound in the same or opposite rotational direction as the first preform layer 2, and / or the second preform layer may be wound in the same or opposite translational direction as the first preform layer 2. Additional preform layers may be wound on top of the second preform layer. These embodiments provide a multi-layer tubular structure that may exhibit improved mechanical properties in the finished composite product compared to a single-layer tubular structure.

[0073] For example, a preferred embodiment for manufacturing sporting goods such as golf club shafts is a 2-ply or 3-ply preform, in which the shaft comprises a stack of two 2-ply or 3-ply preforms to form a 4-ply or 6-ply multilayer structure. In each 2-ply or 3-ply preform, the first ply may comprise parallel-oriented UD fibers that are oriented substantially longitudinally along the shaft after the winding step described above, and one or two adjacent second plies may each comprise parallel-oriented fibers that are oriented helically around the shaft, e.g., at an angle of 30 to 45 degrees relative to the longitudinal axis of the shaft, after the winding step described above. For example, a 3-ply preform may provide fibers at 0, +45, and -45 degrees relative to the longitudinal axis of the shaft.

[0074] During the winding step, the preform layer(s) are typically wrapped under tension, such that the initial wrap places the preform layer(s) in full contact with the underlying surface, e.g., the outer circumferential surface of a mandrel for the first or only preform layer. This winding arrangement has particular application when the surface of the preform has some tackiness, such as that exhibited by typical thermoset-containing prepregs at room temperature. However, in alternative embodiments, particularly when the surface of the preform is non-tacky, such as that exhibited by typical dry fiber reinforcement, the initial wrap may be wrapped somewhat looser during the winding step, without applying tension to the preform layer(s), so as to place the preform layer(s) in only partial contact with the underlying surface and / or not completely in the desired position within the final elongated tube. In such embodiments, tension may be applied to the preform layer(s) after the winding step to slide the preform layer(s) under tension into the desired position within the final elongated tube.

[0075] The elongated tube 20 is then molded onto the mandrel 20 to form an elongated tubular shaft 36 comprised of the fiber reinforced resin matrix composite material 38 formed from the preform layers 2. Before or during the molding step, a resin material is provided in contact with the fiber reinforcement 6 of the preform layers 2, and during the molding step, the resin material forms a resin matrix incorporating the fiber reinforcement 6.

[0076] As mentioned above, in some embodiments, the preform layer 2 may comprise a prepreg, in which case the wrapped preform layer(s) 2 may be subjected to elevated temperatures and, optionally, external pressure applied to the outer surface of the elongated tube 20 to form a molded elongated tubular shaft 36.

[0077] In another embodiment, the dry fiber reinforcement 6 is wrapped around the mandrel 20, and then a resin material is added before or during the molding step so that it is provided in contact with the fiber reinforcement 6 of the preform layer 6, for example by liquid resin infusion or by providing an interfering solid resin layer adjacent to the dry fiber reinforcement that liquefies during the molding process and impregnates the fiber reinforcement 6. Thus, during the molding step, the resin material forms a resin matrix that incorporates the fiber reinforcement 6.

[0078] After the forming step, the elongated tubular shaft 36 may be separated from the mandrel 20 to form a hollow tube, or the mandrel 20, or a portion thereof, may be retained within the central longitudinal cavity 40 of the elongated tubular shaft 36 to form a solid part. In either case, the elongated tubular shaft 36 may be further processed to form a desired product, such as a golf club shaft, a fishing rod, or any other elongated tubular item that may be usefully constructed from fiber reinforced resin matrix composite materials.

[0079] During the winding step, the inner edge 16 of the preform layer 2 is shaped and sized so that the inner edge 16 continuously coincides with the outer peripheral surface 26 of the mandrel 20, thereby defining the elongated tube 28 to have a plurality of winding layers 34 forming a spiral 42 around the longitudinal axis LL, with each winding layer 34 being parallel to the longitudinal axis LL, thereby predetermining the shape and configuration of the preform layer 2 based on the geometry of the elongated tube, thereby defining that each winding layer 34 is wrinkle-free and that each region of the winding layer 34 is consistently aligned with the longitudinal axis LL.

[0080] This provides a high quality composite structure in which the fiber orientation and layer structure of the molded tubular product is very precisely controlled and consistently achieved along the entire length of the elongated tubular shaft 36 .

[0081] In accordance with a preferred embodiment of the present invention, the preform layer 2 is shaped and dimensioned such that, when the preform layer 2 is in a planar configuration, at least a portion of the inner edge 16 is defined using a Cartesian coordinate system having an x-axis and a y-axis. The x-axis is parallel to the spacing between the first and second end portions 12, 14 and is parallel to the axis of rotation RR and, therefore, is also parallel to the longitudinal axis LL of the mandrel 20 about which the preform layer 2 is wrapped. The y-axis is parallel to the spacing between the inner and outer edges 16, 18. At least a portion of the inner edge 16 is defined by the following relationship: Bn=f(x n B ,y n B ), where: B is the position of the inner edge relative to the Cartesian coordinate system, n = number of revolutions of the wound preform layer; x n B =f(c i ,e), where c i = Bn, the circumference of the wound preform layer, and e = the thickness of the preform layer;

number

[0082] In other words, the shape and dimensions of the inner edge 16 along its length relative to the longitudinal axis LL, at any location along the length of the inner edge 16 relative to the longitudinal axis LL, are a function of both the preform layer 2, particularly the thickness of the preform layer 2, and the elongated tube 28 being formed, particularly the number of revolutions of the wound preform layer 34 and the circumference of the wound preform layer 34.

[0083] In practice, this relationship can be determined for any mandrel geometry by calculating the location of the inner edge 16 starting from the point where the inner edge 16 meets the first end portion 12 of the preform layer 2, which is the portion of the inner edge 16 that first contacts the outer surface 26 of the mandrel 20 during the winding step.

[0084] From this starting position, the desired location of inner edge 16 on outer circumferential surface 26 of mandrel 20 after one wrapping revolution is calculated, which is a function of the difference in circumference of mandrel 20 after zero wraps and one wrapping revolution, and the rate of change of this difference in circumference. For the second wrapping revolution, the desired location of inner edge 16 on outer circumferential surface 26 of mandrel 20 after the second wrapping revolution is calculated, which is a function of the difference in circumference of mandrel 20 between the first and second wrapping revolutions, the rate of change of this difference in circumference, and the thickness of preform layer 2. Thereafter, the shape and dimensions of inner edge 16 are calculated for each successive wrapping revolution along the entire length of inner edge 16.

[0085] When the outer circumferential surface 30 of the elongated tube 28 has a non-cylindrical geometry, for example, a geometry corresponding to that of the mandrel 20, a corresponding calculation is made for the outer edge 18. However, if the outer circumferential surface 30 of the elongated tube 28 has a cylindrical geometry, the outer edge 18 may comprise a linear edge that is parallel to the x-axis and therefore parallel to the longitudinal axis LL of the mandrel 20.

[0086] By predetermining the exact geometry of the preform layer 2 based on an analysis of how the preform layer 2 gradually wraps around a given mandrel geometry, a consistently reproducible wrapped layer 34 can be achieved that precisely matches the mandrel geometry along the length of the mandrel 20.

[0087] Because the winding is perpendicular to the rotation axis RR, corresponding to the longitudinal axis LL of the mandrel 20, the winding is easily accomplished and can be reliably controlled using a simple control system. This is because by geometrically matching the shape and configuration of the preform layer 2, including the thickness of the preform layer 2, with the shape and configuration of the mandrel 20 and the resulting elongated tube 28, such geometric matching avoids complex and problematic winding parameters.

[0088] In contrast, for example, in conventional tube-forming processes, a preform tape is helically wound around a mandrel with a wrap angle that is an acute angle relative to the longitudinal axis. The outer diameter of the mandrel determines the inner diameter of the tube being formed. As the diameter of the mandrel changes, the tape can easily become misaligned with respect to the desired fiber orientation. For example, changes in the diameter of the mandrel and the tube being formed result in changes in the angle of the tape relative to the mandrel surface. This can result in wrinkling and misaligned fibers in the wound layers, requiring complex and careful control of the winding process by an associated control system to avoid such fiber misalignment.

[0089] Thus, the present invention provides a reliable and consistent method for producing composite tubes with high quality fiber orientation and alignment that is achievable using low cost, simple manufacturing equipment.

[0090] In FIG. 1, the flexible preform layer 2 has a shape and dimensions determined to allow it to be wrapped around a frustoconical mandrel 20 to form an elongated tubular shaft 28 that is frustoconical and has a constant wall thickness.

[0091] Referring to Figure 2, Figure 2a is a plan view of the flexible preform layer 2 of Figure 1 plotted against the x and y axes of a Cartesian coordinate system. Figure 2b shows the flexible preform layer 2 after it has been wrapped around a frustoconical mandrel 20 to form an elongated tube 28, which is subsequently shaped to form an elongated tubular shaft 36 that is frustoconical in shape and has a constant wall thickness. The frustoconical mandrel 20 has a circular cross section.

[0092] As described above, the winding step progressively wraps the flexible preform layer 2 onto the mandrel 20 from the first end portion 12 to the second end portion 14. In FIG. 2a, horizontal lines H shown on the preform layer 2 represent the beginning and end of each successive wound layer as each winding revolution is completed. As winding progresses from the first end portion 12 to the second end portion 14, it can be seen that the separation distance between the horizontal lines H gradually increases as a result of the increase in diameter of the outer surface 30 of the elongated tube 28 going from the relatively smaller diameter end 37 to the relatively larger diameter end 39 of the elongated tube 28, as well as the corresponding increase in the circumference of each successive wound layer 34.

[0093] 1 and 2, the frustoconical surface 26 is inclined at an angle α relative to the longitudinal axis LL of the mandrel 20. The preform layer 2 may be shaped and dimensioned such that, when the preform layer 2 is in a planar configuration, the curved portion of the inner edge 16 is defined by the following relationship, using a Cartesian coordinate system as described above: Bn=f(x n B ,y n B ), where: B is the position of the inner edge relative to the Cartesian coordinate system, n = number of revolutions of the wound preform layer;

number

number

[0094] For more complex tube geometries, this formula can be easily modified to define the shape and dimensions of only a portion of the preform layer 2, this portion having, for example, a circumference 2πr n It is intended that the wire be wrapped around less than one revolution of the mandrel 20 by calculating the ratio of

[0095] Referring to Figure 3, this figure illustrates the wrapping of preform layers 2 around mandrel 20 to form elongated tube 28 comprised of multiple wrap layers 34. Mandrel 20 is frustoconical in shape with a constant tilt angle α relative to the longitudinal axis of mandrel 20. Preform layers 2 have a constant thickness, and the resulting elongated tube 28 has a constant wall thickness. In Figure 3, within the view of elongated tube 28, horizontal lines represent successive wrap layers 34 of preform layers 2 wrapped around mandrel 20 to form elongated tube 28.

[0096] Thus, when the preform layer 28 is wrapped cylindrically around the mandrel 20, the radius of each horizontal line is determined by the following equation, where r0 is the outer radius of the mandrel at the starting point and e is the thickness of the preform layer:

number

[0097] Each horizontal line is defined by two points A and B that intersect the outer and inner tube diameters, respectively, at the following coordinates:

number

number

[0098] Referring to Figure 4, this figure shows the shape and dimensions of the preform layer 2 used to form the elongated tube 28 of Figure 3 when the preform layer is in a planar configuration relative to the Cartesian coordinate system as described above. The y coordinate of the unwrapped planar preform layer 2, as applied to both the inner and outer edges 16, 18 at a given number of wound layers 34, is obtained by calculating the sum of all the circumferences around the previous wound layer 34.

[0099] For a circular cross section, this becomes:

number

number

[0100] Again, for more complex tube geometries, this formula can be easily modified to define the shape and dimensions of only a portion of the preform layer 2, this portion having, for example, a circumference 2πr n It is intended that the wire be wrapped around less than one revolution of the mandrel 20 by calculating the ratio of

[0101] Since the wrap is perpendicular to the rotation axis RR of the mandrel 20, the x coordinate of the inner edge 16 can be calculated as follows:

number

[0102] The x-coordinate of the outer edge 18 can be calculated accordingly.

[0103] The x, y coordinates of the preform layer 2 can therefore be defined as follows:

number

number

[0104] 1 and 2, the preform layer 2 has a typical thickness of 0.17 mm, and the elongated tube 28 typically has a constant thickness of about 2.5 mm, consisting of 15 winding layers 34. However, other preform layer thicknesses, tube thicknesses, and numbers of winding layers 34 may also be used in accordance with the present invention.

[0105] 14 schematically illustrates a portion of an elongated tubular shaft 300 constructed of a fiber reinforced resin matrix composite material 302, in accordance with a further embodiment of the present invention. The shaft 300 comprises an elongated tubular body 304 comprising a stack 306 of winding layers 308. Each winding layer 308 comprises a fiber reinforcement 310 within a resin matrix 312.

[0106] 14, the dimensions of various elements are not to scale and are exaggerated for clarity of illustration. Additionally, the helical edges of the layers 308 are shown perpendicular to the longitudinal axis of the elongated tubular body 304, and therefore the frustoconical inner and outer surfaces of the elongated tubular body 304 are shown as stepped. However, in a physical representation of the embodiment, the wound layers 308 typically have such a thin thickness, and the resin flows during the molding process to contact the entire outer periphery of the mandrel and any outer molded parts such that, within the molded elongated tubular shaft 300, the helical edges of the layers appear to the naked eye to be smooth and sloped on the outer and inner surfaces to match the overall frustoconical shape of the elongated tubular shaft 300.

[0107] The elongated tubular body 304 has an elongated inner circumferential surface 314, which has a first surface portion 316 having a non-cylindrical geometry along at least a portion of the length of the elongated tubular body 304. In this embodiment, the non-cylindrical geometry is a frusto-conical shape, as also shown in Figure 3. The elongated tubular body 304 also has an elongated outer circumferential surface 318, which has a non-cylindrical geometry, in this embodiment, a frusto-conical shape, as also shown in Figure 3.

[0108] The stack 306 of wound layers 308 of fiber reinforcement 310 comprises a fiber layer 320. The fiber layer 320 comprises at least one ply of fiber reinforcement 310.

[0109] In a preferred embodiment, the fiber reinforcement 310 comprises structural fibers that are uniformly oriented relative to a cylindrical coordinate system about the longitudinal axis LL. Preferably, the structural fibers are contained in unidirectional (UD) fiber plies.

[0110] The fiber layer 320 is helically wrapped around the longitudinal axis LL of the elongated tubular body 304 to form a stack 306 of wrapped layers 308. Each wrapped layer 308 is parallel to the longitudinal axis LL.

[0111] In a portion 322 of the stack 306 of winding layers 308 that circumferentially surrounds the first surface portion 316, the fiber layer 320 has a non-constant width that varies non-linearly with the change in radius of the elongated inner circumferential surface 314 within the portion 322, as shown in FIG.

[0112] The fiber reinforcement 310 comprises fibers 324 that are uniformly oriented along the length of the elongated tubular body 304 relative to a cylindrical coordinate system about the longitudinal axis LL of the elongated tubular body 304. The fiber orientation of any such portion 322 is independent of the geometry of the elongated inner circumferential surface 314 and the elongated outer circumferential surface 318 of that portion 322.

[0113] In this embodiment, along the first surface portion 316, the inner edge 326 of the fiber layer 320 is coincident with the inner circumferential surface 314 and forms a continuous inner spiral line HL3 that extends along the plurality of wound layers 308. The continuous inner spiral line HL3 has a uniform pitch between successive helical turns of the wound layer 308. The continuous inner spiral line HL3 typically extends along at least ten of the wound layers 308.

[0114] In this embodiment, at least a portion 328 of the inner edge 326 is curved relative to a transverse plane TT extending perpendicular to the longitudinal axis LL, as shown correspondingly in Figures 1-3 with respect to the preform layer 2 used to form the elongated tubular body 304. Typically, the curved portion 328 of the inner edge 326 is convexly curved relative to the fiber layer 320.

[0115] In this embodiment, the elongated circumferential surface 318 has a non-cylindrical geometry and the elongated tubular body 304 has a constant thickness along at least a portion of its length. In another embodiment, as shown below with reference to Figures 9-13, the elongated circumferential surface may have a cylindrical geometry and / or the elongated tubular body may have a non-constant thickness along at least a portion of its length.

[0116] FIG. 5 illustrates a further embodiment of the present invention, which is a variation of the embodiment of FIGS. 2a and 2b. FIG. 5a is a plan view of a flexible preform layer 52 plotted against the x- and y-axes of a Cartesian coordinate system, and FIG. 5b illustrates the flexible preform layer 52 after being wrapped around a frustoconical mandrel 54 to form an elongated tube 56, which is subsequently shaped to form an elongated tubular shaft having a frustoconical shape and a constant wall thickness. Compared to the embodiment of FIGS. 2a and 2b, the only variation is that the preform layer 52 includes holes 58 extending through the thickness of the preform layer 52. The holes 58 are located inside the first and second end portions 12, 14 and the inner and outer edges 16, 18. The holes 58 are circular, but may have any other shape and dimensions. As shown in FIG. 3b, the flexible preform layer 52 can be wrapped to form an elongated tube 56 and provide openings, depressions, or cavities within the elongated tube 56. In another embodiment, there may be multiple holes.

[0117] Figure 6 shows a further embodiment of the present invention, which is a further variation of the embodiment of Figures 2a and 2b. Figure 6a is a plan view of a flexible preform layer 62 plotted against the x- and y-axes of a Cartesian coordinate system, and Figure 6b shows the flexible preform layer 62 after being wrapped around a frustoconical mandrel 64 to form an elongated tube 66, which is subsequently shaped to form an elongated tubular shaft having a frustoconical shape and a constant wall thickness. Compared to the embodiment of Figures 2a and 2b, the only variation is that the preform layer 62 is comprised of its first and second layer portions 68, 70. The first layer portion 68 is first wrapped around the mandrel 64 as described above, and then the second layer portion 70 is subsequently wrapped around the mandrel 64, at least partially over the first layer portion 68, as described above. Additional layer portions may optionally be provided.

[0118] In the illustrated embodiment, the first and second layer portions 68, 70 have the same thickness, thus forming a constant thickness elongated tube 66. However, the first and second layer portions 68, 70 may have different thicknesses such that the elongated tube 66 has first and second thickness regions, preferably with a transition region therebetween.

[0119] Alternatively or additionally, the first and second layer portions 68, 70 may have different fiber reinforcements, resins, orientations, etc.

[0120] Figure 7 shows a further embodiment of the invention, which is a further variation of the embodiment of Figures 2a and 2b. Figure 7a is a plan view of a flexible preform layer 72 plotted relative to the x and y axes of a Cartesian coordinate system, and Figure 7b shows the flexible preform layer 72 after it has been wrapped around a mandrel 74 to form an elongated tube 76, which is subsequently shaped to form an elongated tubular shaft having a constant wall thickness. The only variation compared to the embodiment of Figures 2a and 2b is that the mandrel 74, and consequently the elongated tube 76, is not frustoconical with a circular cross-section, but instead is frustopyramidal with a square cross-section.

[0121] As shown in FIG. 7 a , the square profile of the elongated tube 76 can be incorporated into the calculation of the vibrating edge profile 77 on the inner and outer edges 75 , 79 of the preform layer 72 .

[0122] In alternative embodiments, the mandrel may have other non-circular cross-sections, and may have any other regular (eg, polygonal, elliptical) or irregular shape.

[0123] Figure 8 shows a further embodiment of the present invention, which is a further variation of the embodiment of Figures 2a and 2b. Figure 8a is a plan view of a flexible preform layer 82 plotted relative to the x and y axes of a Cartesian coordinate system, and Figure 8b shows the flexible preform layer 82 after it has been wrapped around a mandrel 84 to form an elongated tube 86, which is subsequently shaped to form an elongated tubular shaft having a constant wall thickness. Compared to the embodiment of Figures 2a and 2b, the only variation is that the thickness of the preform layer 82 has been increased, resulting in a reduced number of wrapper layers for a given thickness of the elongated tube 86.

[0124] In the embodiment of FIG. 8, the typical thickness of the preform layer is 0.215 mm, and the elongated tube typically has a constant thickness constructed from eight wrapped layers, i.e., a typical tube thickness of about 1.7 mm.

[0125] A comparison of Figures 2 and 8 shows that varying the preform thickness also changes the geometry of the curvature of the inner and outer edges 85, 89 of the preform layer 82 because, as discussed above, the thickness of the preform layer 82 is a variable in calculating the shape and configuration of the preform layer 82 to produce a given elongated tube geometry.

[0126] Figure 9 shows a further embodiment of the invention, which is a further variation of the embodiment of Figures 2a and 2b: Figure 9a is a plan view of flexible preform layer 90 plotted relative to the x and y axes of a Cartesian coordinate system, and Figure 9b shows flexible preform layer 90 after it has been wrapped around mandrel 91 to form elongated tube 92, which is subsequently shaped to form an elongated tubular shaft having a variable wall thickness.

[0127] Preform layers 90 and mandrel 91 are shaped and sized to form a cylindrical outer surface 93 of elongated tube 92. Specifically, outer edge 94 is linear and parallel to the axis of rotation, rather than concavely curved as in the embodiment of Figures 2-8.

[0128] 2a and 2b, the outer peripheral surface 95 of the mandrel 91 further comprises cylindrical surfaces 96a, 96b adjacent the frustoconical surface 97 at at least one end 98a, 98b of the frustoconical surface 97. The preform layer 90 is shaped and dimensioned such that when the preform layer 90 is in a planar configuration, the second portions 99a, 99b of each of the inner edges 100 that contact the cylindrical surfaces 96a, 96b during the winding step are linear during the winding step and parallel to the axis of rotation and the longitudinal axis.

[0129] Figure 10 shows a further embodiment of the invention, which is a further variation of the embodiment of Figures 2a and 2b: Figure 10a is a plan view of flexible preform layer 102 plotted relative to the x and y axes of a Cartesian coordinate system, and Figure 10b shows flexible preform layer 102 after it has been wrapped around a mandrel 103 to form an elongated tube 104, which is subsequently shaped to form an elongated tubular shaft having a variable wall thickness.

[0130] The preform layer 102 and mandrel 103 are shaped and sized to form first and second cylindrical outer surfaces 105a, 105b on opposite ends 106a, 106b of the elongated tube 104, with a conical outer surface 105c interconnecting the first and second cylindrical outer surfaces 105a, 105b. Additionally, the first and second cylindrical outer surfaces 105a, 105b are external to the respective first and second cylindrical walls 101a, 101b. The first cylindrical wall 101a has a wall thickness greater than the wall thickness of the second cylindrical wall 101b. The conical outer surface 105c is external to the conical wall 101c, which gradually increases in wall thickness from the first cylindrical wall 101a to the second cylindrical wall 101b.

[0131] The preform layer 102 is shaped and dimensioned so that, when the preform layer 102 is in a planar configuration, the second portions 107a, 107b of each of the inner edges 108 that contact the cylindrical surfaces 109a, 109b of the mandrel 103 during the winding step are linear and parallel to the axis of rotation and the longitudinal axis during the winding step. Additionally, the preform layer 102 is shaped and dimensioned so that the outer edges 110 include a central curved portion 112 between the opposing linear portions 113a, 113b. The opposing linear portions 113a, 113b of each of the outer edges 110 that are away from the cylindrical surfaces 109a, 109b of the mandrel 103 during the winding step are linear and parallel to the axis of rotation and the longitudinal axis during the winding step.

[0132] Figure 11 shows a further embodiment of the invention which is a further variation of the embodiment of Figures 2a and 2b: Figure 11a is a plan view of flexible preform layer 115 plotted relative to the x and y axes of a Cartesian coordinate system, and Figure 11b shows flexible preform layer 115 after it has been wrapped around mandrel 116 to form elongated tube 117, which is subsequently shaped to form an elongated tubular shaft having a variable wall thickness.

[0133] 2a and 2b to have a constant taper angle for a frusto-conical shape. However, the outer edge 119 of the preform layer 115 is shaped and sized to form an outer surface 120 of the elongated tube 117 having a varying geometry and dimensions. Specifically, the outer surface 120 has a first cylindrical portion 121, a first tapered portion 122 at a first taper angle, a second tapered portion 123 at a second taper angle, a third tapered portion 124 at a third taper angle, a fourth tapered portion 125 at a fourth taper angle, a second cylindrical portion 126, and a fifth tapered portion 127 at a fifth taper angle.

[0134] Using the calculations described above for the previous embodiment, the outer edge 119 of the preform layer 115 is shaped and dimensioned to provide a first linear portion 131 to form the first cylindrical portion 121, a first curved portion 132 to form the first inclined portion 122, a second curved portion 133 to form the second inclined portion 123, a third curved portion 134 to form the third inclined portion 124, a fourth curved portion 135 to form the fourth inclined portion 125, a second linear portion 136 to form the second cylindrical portion 126, and a fifth curved portion 137 to form the fifth inclined portion 127.

[0135] Figure 12 shows a further embodiment of the invention, which is a further variation of the embodiment of Figures 2a and 2b. Figure 12a is a plan view of a flexible preform layer 140 plotted relative to the x and y axes of a Cartesian coordinate system, and Figure 12b shows the flexible preform layer 140 after it has been wrapped around a mandrel 142 to form an elongated tube 144, which is subsequently shaped to form an elongated tubular shaft having a variable wall thickness.

[0136] The mandrel 142 is shaped and dimensioned similarly to the embodiment of Figures 2a and 2b so as to have a constant inclination angle for a frusto-conical shape, except that the mandrel 142 incorporates outwardly directed peripheral protrusions 148 on opposite edges of a central inclined surface 154 having oppositely inclined frusto-conical surfaces 150, 152 having different inclination angles relative to the longitudinal axis of the mandrel 142.

[0137] Using the calculations described above for the previous embodiment, the inner edge 156 of the preform layer 140 has opposing lower and upper curved portions 158, 160 for wrapping around the lower and upper angled portions 162, 164 of the mandrel 142 on opposite edges of the projections 148. The inner edge 156 further has an inwardly oriented notch 166 for wrapping around the projections 148. The notch 166 is defined by a first curved portion 168 for wrapping around the lower frustoconical surface 150, a second curved portion 170 for wrapping around the central angled surface 154, and a third curved portion 172 for wrapping around the upper frustoconical surface 152.

[0138] The outer edge 174 of the preform layer 140 is linear and parallel to the axis of rotation to form an outer surface 176 of the cylindrical elongated tube 144, as in the embodiment of FIG.

[0139] Figure 13 shows a further embodiment of the invention which is a further variation of the embodiment of Figure 12. Figure 13a is a plan view of a flexible preform layer 180 plotted relative to the x and y axes of a Cartesian coordinate system, and Figure 13b shows the flexible preform layer 180 after it has been wrapped around a mandrel 182 to form an elongated tube 184, which is subsequently shaped to form an elongated tubular shaft having a variable wall thickness.

[0140] 12 embodiment, with the exception that the mandrel 182 incorporates an outwardly directed peripheral projection 186 having a recessed groove 188. The projection 186 has oppositely sloped frustoconical surfaces 190, 192 on either side of a central cylindrical surface 194, with different slope angles relative to the longitudinal axis of the mandrel 182, and the groove 188 is defined by a recessed sloped surface 196 connecting between the frustoconical surface 192 and the main outer frustoconical surface 198 of the frustoconical-shaped mandrel 182.

[0141] Using the calculations described above for the previous embodiment, the inner edge 200 of the preform layer 180 has opposing lower and upper curved portions 202, 204 for wrapping around the lower and upper angled portions 206, 208 of the mandrel 182 on either side of the protrusion 186. The inner edge 200 further has an inwardly oriented notch 210 for wrapping around the protrusion 186. The notch 210 is defined by a first curved portion 212 for wrapping around the lower frustoconical surface 190, a first linear portion 214 for wrapping around the central cylindrical surface 194, a second curved portion 216 for wrapping around the upper frustoconical surface 192, and a third curved portion 218 for filling the groove 188 between the concave angled surface 196 and the upper angled portion 208 of the main outer frustoconical surface 198.

[0142] The outer edge 220 of the preform layer 180 is linear and parallel to the axis of rotation to form the outer surface 222 of the cylindrical elongated tube 184, as in the embodiment of FIG.

[0143] The method for manufacturing a long tubular shaft composed of a fiber-reinforced resin matrix composite material according to the present invention is not limited to the embodiments detailed above. Specifically, in further embodiments of the present invention (not shown), the mandrel can have any combination of circumferential shape, dimensions, and cross-sectional shape. The number of preform layers wound around the mandrel can also be greater than one. Furthermore, the number of plies of the preform layer can be one or more, and the orientation of the fibers of the plies relative to the direction of the preform layer parallel to the axis of rotation can be at any angle suitable to provide the desired performance of the composite structure. Some preferred embodiments of the present method should be selected to form a fiber-reinforced composite structure in which the proportion (e.g., by weight) of unidirectional fibers having an orientation along the axis of the tubular shaft that is beneficial to the primary performance of the composite structure is greater than the proportion (e.g., by weight) of fibers that may optionally be unidirectional fibers oriented obliquely relative to that direction.

Claims

1. 1. A method of manufacturing an elongated tubular shaft constructed from a fiber reinforced resin matrix composite material, the method comprising: a) providing an elongate mandrel having a longitudinal axis, first and second opposed ends spaced apart along the longitudinal axis, and an outer circumferential surface that is non-cylindrical along at least a portion of the length of the mandrel that extends along the longitudinal axis; b) providing a preform layer comprising fiber reinforcement, the preform layer having first and second end portions spaced apart and inner and outer edges spaced apart, the inner and outer edges extending from the first end portion to the second end portion, and wherein when the preform layer is in a planar configuration, at least the inner edge is non-linear, and a spacing between the inner and outer edges varies along a length of the preform layer extending between the first and second end portions; c) positioning the first end portion of the preform layer adjacent the first end of the mandrel in a starting configuration with the inner edge oriented toward the mandrel and the outer edge oriented away from the mandrel; d) winding the preform layer around the mandrel so that the outer circumferential surface of the mandrel is gradually covered by the wound preform layer to form an elongated tube, whereby, within the elongated tube, the inner edge contacts the outer circumferential surface of the mandrel and the outer edge is disposed on the outer circumferential surface of the elongated tube, during the winding step, the mandrel and the preform layer are rotated relative to each other about an axis of rotation along the longitudinal axis of the mandrel, and the preform layer is continuously fed onto the mandrel along a feed path perpendicular to the longitudinal axis of the mandrel from the first end portion to the second end portion of the preform layer; e) molding the elongated tube over the mandrel to form an elongated tubular shaft comprised of fiber reinforced resin matrix composite material formed from the preform layers; Equipped with before or during step e), a resin material is provided in contact with the fiber reinforcement of the preform layer, and during step e), the resin material forms a resin matrix incorporating the fiber reinforcement; In step b), the inner edge of the preform layer is shaped and sized in step d) so that the inner edge continuously coincides with the outer circumferential surface of the mandrel and the elongated tube comprises a plurality of winding layers forming a spiral around the longitudinal axis, each winding layer being parallel to the longitudinal axis.

2. The method of claim 1 , wherein each wrapped layer is wrinkle-free and each region of the wrapped layer is consistently parallel to the longitudinal axis.

3. 3. The method of claim 1 or claim 2, wherein in step d), along at least a portion of the length of the elongated tube, contact between at least a portion of the inner edge and a region of the outer circumferential surface of the non-cylindrical mandrel forms a continuous inner helical line extending along a plurality of the wound layers that coincides with the outer circumferential surface of the mandrel.

4. The method of claim 3 , wherein the continuous inner spiral line has a uniform pitch between successive spiral turns of the winding layer.

5. 5. The method of claim 3 or claim 4, wherein the continuous inner spiral line extends along at least two winding layers of the wound preform layer.

6. 6. The method of claim 1, wherein in step b) the preform layer is shaped and dimensioned such that at least a portion of the inner edge is curved or convexly curved when the preform layer is in a planar configuration.

7. The method of any one of claims 1 to 6, wherein the mandrel is frustoconical having a frustoconical surface.

8. 8. The method of claim 7, wherein the outer peripheral surface further comprises a cylindrical surface adjacent the frusto-conical surface at at least one end of the frusto-conical surface, and wherein in step b), the preform layer is shaped and dimensioned such that when the preform layer is in a planar configuration, a second portion of the inner edge that contacts the cylindrical surface in step d) is linear and parallel to the longitudinal axis in steps c) and d).

9. 9. The method of claim 7 or 8, wherein the outer peripheral surface further comprises a second frusto-conical surface inclined in an opposite direction to the frusto-conical surface, the second frusto-conical surface being adjacent to or spaced from an end of the frusto-conical surface, and wherein in step b) the preform layer is shaped and dimensioned such that, when the preform layer is in a planar configuration, a third portion of the inner edge that contacts the second frusto-conical surface in step d) is cut into the inner edge in steps c) and d) to become part of a concave opening inclined relative to the longitudinal axis.

10. 10. The method of claim 1, wherein in step b) the preform layer is shaped and dimensioned such that at least a portion of the outer edge opposite the inner edge is curved when the preform layer is in a planar configuration, and in step d) the curved portion of the outer edge forms a continuous outer spiral line along at least a portion of the length of the elongated tube.

11. In step b), the preform layer is shaped and sized so that at least a portion of the outer edge opposite the inner edge is curved when the preform layer is in a planar configuration; and in step d), the curved portion of the outer edge forms a continuous outer helical line along at least a portion of the length of the elongated tube; 4. The method of claim 3, wherein the continuous outer spiral line is equidistant from the continuous inner spiral line along the plurality of wound layers such that the elongated tube has a constant thickness along the portion thereof.

12. 12. The method of any one of claims 1 to 11, wherein in step b), the preform layer is shaped and dimensioned such that at least a portion of the outer edge is linear when the preform layer is in a planar configuration, and in steps c) and d), the linear portion of the outer edge is parallel to the longitudinal axis in steps c) and d), and the outer surface of the elongated tube formed by the linear portion is cylindrical.

13. The mandrel is frustoconical having a frustoconical surface; 13. The method of claim 12, wherein the outer peripheral surface further comprises a cylindrical surface adjacent the frusto-conical surface at at least one end of the frusto-conical surface, and in step b), the preform layer is shaped and dimensioned such that, when the preform layer is in a planar configuration, a second portion of the inner edge that contacts the cylindrical surface in step d) is linear and parallel to the longitudinal axis in steps c) and d).

14. 14. The method of claim 13, wherein the outer peripheral surface further comprises a second frusto-conical surface inclined in an opposite direction to the frusto-conical surface, the second frusto-conical surface being adjacent to or spaced from an end of the frusto-conical surface, and the preform layer is shaped and dimensioned such that, when the preform layer is in a planar configuration, a third portion of the inner edge contacting the second frusto-conical surface in step d) is cut into the inner edge in steps c) and d) to become part of a concave opening inclined relative to the longitudinal axis.

15. 15. The method of any one of claims 1 to 14, wherein the fiber reinforcement comprises structural fibers that are aligned parallel to the longitudinal axis during step c) and that remain constantly oriented relative to a cylindrical coordinate system about the longitudinal axis during step d), the structural fibers being comprised in unidirectional (UD) fiber plies.

16. 1. An elongated tubular shaft constructed of a fiber reinforced resin matrix composite material, the shaft comprising an elongated tubular body comprising a stack of wound layers, each wound layer comprising fiber reinforcement in a resin matrix, the elongated tubular body having an elongated inner circumferential surface having a first surface portion having a non-cylindrical geometry along at least a portion of the length of the elongated tubular body, and an elongated outer circumferential surface, the stack of wound layers of fiber reinforcement comprising a fiber layer, the fiber layer comprising at least one ply of fiber reinforcement, the fiber layer being wound around the elongated tubular body to form the stack of wound layers.

1. An elongated tubular shaft, the elongated tubular shaft being spirally wound around a longitudinal axis of the elongated tubular body, each winding layer being parallel to the longitudinal axis, wherein in a portion of the stack of winding layers circumferentially surrounding the first surface portion, the fiber layers have a non-constant width that varies non-linearly with changes in radius of the elongated inner circumferential surface within the portion, the fiber reinforcement comprising fibers that are constantly oriented along the length of the elongated tubular body with respect to a cylindrical coordinate system about the longitudinal axis of the elongated tubular body, and the fiber orientation of any of the portions is independent of the geometric shape of the elongated inner circumferential surface and elongated outer circumferential surface of that portion.

17. 17. The elongate tubular shaft of claim 16, wherein along the first surface portion, an inner edge of the fiber layer is coincident with the inner circumferential surface and forms a continuous inner spiral line extending along a plurality of the wound layers.

18. 18. The elongate tubular shaft of claim 17, wherein the continuous inner spiral line extends along at least ten of the winding layers.

19. 19. The elongate tubular shaft of claim 17 or claim 18, wherein at least a portion of the inner edge is curved relative to a transverse plane extending perpendicular to the longitudinal axis.

20. 20. The elongate tubular shaft of claim 19, wherein the curved portion of the inner edge is convexly curved relative to the fiber layer.

21. 21. The elongate tubular shaft of any one of claims 16 to 20, wherein the first surface portion is frustoconical.

22. 22. The elongate tubular shaft of any one of claims 16 to 21, wherein the elongate inner circumferential surface further comprises a cylindrical surface adjacent the first surface portion at at least one end of the first surface portion, and the fiber layer has end portions defining the cylindrical surface and having edges that are linear and parallel to the longitudinal axis.

23. 23. The elongate tubular shaft of any one of claims 16 to 22, wherein the elongate inner circumferential surface further comprises a second surface portion having a non-cylindrical geometry and sloping in an opposite direction to the first surface portion, the second surface portion being adjacent to or spaced from a terminal end of the first surface portion.

24. 24. The elongated tubular shaft of any one of claims 16 to 23, wherein the fiber reinforcement comprises structural fibers that are uniformly oriented relative to a cylindrical coordinate system about the longitudinal axis of the elongated tubular body, the structural fibers being contained in unidirectional (UD) fiber plies.

Images