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WO1996009159A1 - Procede de fabrication de tubes en materiaux composites a renforcement interne - Google Patents

Procede de fabrication de tubes en materiaux composites a renforcement interne Download PDF

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Publication number
WO1996009159A1
WO1996009159A1 PCT/US1995/012430 US9512430W WO9609159A1 WO 1996009159 A1 WO1996009159 A1 WO 1996009159A1 US 9512430 W US9512430 W US 9512430W WO 9609159 A1 WO9609159 A1 WO 9609159A1
Authority
WO
WIPO (PCT)
Prior art keywords
tube
mandrels
overwrapped
wall
plurahty
Prior art date
Application number
PCT/US1995/012430
Other languages
English (en)
Inventor
Howard A. Lindsay
Scott D. Cokeing
Original Assignee
Viatech, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Viatech, Inc. filed Critical Viatech, Inc.
Publication of WO1996009159A1 publication Critical patent/WO1996009159A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D23/00—Producing tubular articles
    • B29D23/001—Pipes; Pipe joints
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
    • B29C70/34—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation
    • B29C70/342—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation using isostatic pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/40—Shaping or impregnating by compression not applied
    • B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
    • B29C70/44—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using isostatic pressure, e.g. pressure difference-moulding, vacuum bag-moulding, autoclave-moulding or expanding rubber-moulding
    • B29C70/446—Moulding structures having an axis of symmetry or at least one channel, e.g. tubular structures, frames
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L9/00—Rigid pipes
    • F16L9/18—Double-walled pipes; Multi-channel pipes or pipe assemblies
    • F16L9/19—Multi-channel pipes or pipe assemblies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2023/00—Tubular articles
    • B29L2023/22—Tubes or pipes, i.e. rigid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/60—Multitubular or multicompartmented articles, e.g. honeycomb
    • B29L2031/601—Multi-tubular articles, i.e. composed of a plurality of tubes

Definitions

  • the present invention is directed to a method for making structural tubes from lightweight composite materials, and is directed more particularly to a method for making internally reinforced structural tubes for use in manufacturing bicycles that have tube and lug frames.
  • Bicycle manufacturer's have long recognized the advantages of constructing bicycle frames from lightweight composite materials, such as those composed of fibers of graphite, glass, etc. that have been impregnated with synthetic curable resins, typically epoxy resins.
  • Bicycle frames constructed of such materials are desirable both because they are light in weight and because they have a high strength and stiffness. This combination of properties is particularly desirable in specialized bicycles such as racing and off-road bicycles, the former because a lightweight frame increases speed and reduces rider fatigue, and the latter because a strong frame is better able to withstand the stresses and shocks that are associated with riding over rough surfaces.
  • Bicycle frames that are made out of composite materials are ordinarily of one of two types.
  • a first of these types has a single piece or unitary frame that includes a plurality of relatively long tubular segments, e.g., top tube, down tube, etc., that are connected together by junction structures, e.g., head junction, seat junction, etc..
  • junction structures e.g., head junction, seat junction, etc.
  • This type of construction is referred to as unitary because all parts of the frame are cured at the same time in the same mold.
  • One method for manufacturing a bicycle frame of this type is described in U.S. patent no. 5,158,733 (Trimble).
  • a second of these types has a multi-piece frame that is made up of a plurality of discrete relatively long tubes and junction structures which are formed and cured separately. These separate pieces are then fitted together and bonded by a suitable curable resin which is cured in a separate curing operation. Frames that are constructed in this manner are commonly referred to as "tube and lug" frames.
  • a frame of this type is described in U.S. patent no. 5,116,071 (Calfee).
  • Both of the above-mentioned types of bicycle frames may be constructed using a number of different curing methods.
  • One of these curing methods uses a heat-resistant inflatable bladder which is disposed inside of the part to be cured, and which is inflated during curing to compress the composite material against the inside of its curing mold and thereby produce a void-free composite structure. After the part is cured, the inflatable bladder is deflated and removed, leaving a thin-walled hollow part which is ready for final finishing and use.
  • Another of these methods known as the "trapped rubber method"
  • a heat expandable rubber (usually silicone) mandrel which is disposed inside of the part to be cured, and which expands during curing to compress the composite material against the inside of its curing mold.
  • the part and its mandrel are cooled until the mandrel contracts to a size small enough to be removed from the part, again leaving a hollow thin-walled part which is ready for final finishing and use.
  • tubes constructed by the above-described methods are both relatively strong in relation to their weight, they still occasionally fail during use.
  • One reason is that tradeoffs must be made between the weight and the strength and stiffness of a bicycle frame. More particularly, if the frame is made strong enough to meet all conceivable conditions of use, it will have a weight disadvantage vis-a-vis competing, lighter bicycle frames. If it is made fight enough to provide a weight advantage vis-a-vis competing, stronger bicycle frames, it may undergo a structural failure during conditions of severe use. The making of this tradeoff is comphcated by the fact that the geometry of a bicycle frame makes accurate calculations of optimum structural values extremely difficult, if not impossible. Thus, there exists a need for a bicycle frame which includes structural tubes that are appreciably stronger and stiffer than currently available tubes, but that do not weigh appreciably more than currently available tubes.
  • a method for making composite structural tubes which appreciably increases their strength and stiffness without appreciably increasing their weight.
  • the method of the invention produces such tubes by modifying previously used methods to include additional steps which result in the formation, within the tube, of internal reinforcing structures that are cured at the same time as the tube, i.e., are co- cured, and are integral therewith, i.e., are free of separately cured seams or joints.
  • additional steps make possible the making of tubes that have a wide variety of internal reinforcing structures made up of inner walls or septums which extend in bracing relationship to the outer wall of the tube.
  • Such internal reinforcing structures allow the construction of bicycle frames which are tailored to exhibit increased strength and stiffness along particular axes and/or in planes in which bicycle frames are usually weak or "soft", and yet which do not weigh appreciably more than conventional frames.
  • the method of the invention contemplates the use of two or more heat expandable mandrels, each of which has a cross-sectional shape which is similar to the cross-sectional shape of one of the open spaces or chambers into which the internal reinforcing structure divides the interior of the tube.
  • a round tube which is to be reinforced by a single diametrically disposed inner wall will include two mandrels, each having a semi-circular cross section.
  • a square tube which is to be reinforced by four inner walls that extend from the center of the square to each of its corners, on the other hand, will include four mandrels, each having a right triangular cross section.
  • the method of the present invention further contemplates the steps of individually wrapping each mandrel with a plurality of layers of pre- impregnated fiber reinforced material ("prepregs").
  • prepregs may include prepregs of any of a variety of types, e.g., unidirectional tape or isotropic fabric, or any combination of types, and may be applied with orientations appropriate to the direction or directions along which the tube is to be strengthened. The number of such layers is determined by the desired thickness of the inner walls.
  • next steps contemplated by the method of the invention include the assembly of the individually wrapped mandrels into a single multi-mandrel body, and the overwrapping thereof by additional layers of prepregs, the number of such layers corresponding to the desired thickness of the outer tube wall.
  • the combined thicknesses of the layers that form the outer wall of the tube will be larger than the combined thicknesses of the layers that form the inner walls of the tube. The latter relationship is desirable because it assures that the weight of an internally reinforced tube is not appreciably greater than that of an unreinforced tube of similar dimensions.
  • the remaining steps of the method of the invention namely: packing the assembled multi-mandrel body into a mold; maintaining the mold and its contents at a temperature and for a time dependent on the type of curable resin used; and cooling the multi-mandrel body are conventional, except that, after cooling, each of the mandrels is separately removed prior to the final processing of the tube.
  • the tube may be used in the those encountered during off-road riding, which tend to cause the buckling of thin walled tubes.
  • the method of the present invention may also be used to construct tubes having internal structures with functions that are only incidentally or indirectly related to the reinforcement of the tube.
  • An example of a tube having an internal structure of this type is a bicycle tube that has one or more internal passages for the routing of electrical or mechanical cables.
  • Tubes of this type may be constructed in accordance with the method of the invention by including the additional step of "building out" particular parts of the assembled multi-mandrel body with strips of prepreg that do not wrap around the body. Provided that they are added at the proper stage of construction, and at the proper places, such added strips can be used to produce internal structures having any desired shape and thickness, including regions of variable thickness.
  • the present invention is also directed to the internally reinforced tubes that are produced by its use.
  • the present invention is directed to tubes produced by the method of the invention that are adapted for use in tube and lug type bicycle frames.
  • FIGS. 1 through 4 show end views of circular tubes that include internally disposed reinforcing structures that have an "open” or "star-like” configuration;
  • Figs. 5 and 6 show end views of circular tubes that include internally disposed reinforcing structures that have a "closed” or “spar-like” configuration;
  • Figs. 7, 8 and 9 show end views of internally reinforced tubes having non-circular shapes
  • Fig. 10 is an end view of a circular tube having an internally disposed reinforcing structure which is offset from the center of the tube and which defines a plurality of internal passages for the cables used to control the operation of the bicycle;
  • Fig. 11 is an end view of a circular tube having a relatively thick internal reinforcing structure which includes a plurality of symmetrically distributed passages;
  • Fig. 12 is an end view of a circular tube which includes an internal reinforcing structure that includes a combination of reinforcing members having "open” and a “closed” configurations;
  • Figs. 13A through 13F show the steps performed in making the reinforced tube shown in Fig. 1;
  • Figs. 14A through 14F show the steps performed in making the reinforced tube shown in Fig. 6;
  • Figs. 15A through 15F show the steps performed in making the reinforced tube shown in Fig. 10; and Fig. 16 is an enlarged end view of an assembled multi-mandrel body that shows the layered structure thereof in greater detail.
  • tube 10-1 includes a circular outer wall 12-1 which is internally reinforced by an inner wall 14-1 that is oriented along a diameter of tube 10-1.
  • walls 12-1 and 14-1 are referred to separately, as if they were distinct elements, they are actually differently functioning sections of a single piece unitary or monolithic structure, i.e., a structure which has no joints between separately cured parts.
  • tube 10-1 to have a strength which is high both in relation to otherwise similar tubes that lack an internal reinforcing structure and with respect to tubes which include an internal reinforcing structure, but which are not as strong as they might be because these reinforcing structures are bonded to the tube in a separate curing step.
  • An internally reinforced tube of the latter type is described in U.S. patent no. 4,900,048 (Derujinsky)
  • tube 10-1 includes internal layers of a composite material composed of filaments that are bonded together into generally planar pieces by a heat curable resin, these layers are bonded at the same time and in a single curing step. During this simultaneous or co-curing, these layers lose their separate identities becoming, in effect, commonly encased in a resinous matrix that is free of discontinuities. Because the same is true of the layers in outer wall 12-1 and inner wall 14-1, there also no discontinuities between these structures.
  • tube 10-1 of Fig. 1 is ideally suited for use in bicycle frames which are of tube and lug construction.
  • tubes of the type shown in Fig. 1 may be used in any one or more of the long tubes that are disposed between the tube junction members that connect the tubes together. When so used, the tubes cause the frame as a whole to exhibit generally the same desirable combination of properties as the tubes themselves.
  • the method of the invention, and the internally reinforced tubes constructed by its use are not restricted to use in bicycle frames, and may be used more generally in any structure which requires a combination of high strength, high stiffness and fight weight.
  • FIGs. 2, 3 and 4 there are shown end views of tubes constructed in accordance with the method of the invention which utilize internal reinforcing structures having configurations different from that of Fig. 1. More particularly, Figs. 2, 3 and 4 show tubes 10-2, 10-3 and 10-4, respectively, which all include internal reinforcing structures in which a plurality of inner wall segments form at least one intersection within the interior of the tube.
  • Fig. 2 shows a tube 10-2 which includes a diametrically disposed inner wall segment 14-2 which intersects and bridges secantially disposed inner wall segments 16-2 and 18-2 to form a reinforcing structure having a cross section similar to that of an I-beam.
  • Fig. 2 shows a tube 10-2 which includes a diametrically disposed inner wall segment 14-2 which intersects and bridges secantially disposed inner wall segments 16-2 and 18-2 to form a reinforcing structure having a cross section similar to that of an I-beam.
  • FIG. 3 shows a tube 10-3 which includes three generally radially disposed inner wall segments 14-3, 16-3 and 18-3 which intersect at the center of the tube to form a reinforcing structure having a Y-shaped configuration.
  • Fig. 4 shows a tube 12-4 which includes four generally radially disposed inner wall segments 14-4 through 20-4 which intersect at the center of the tube to form a reinforcing structure having a cross-shaped configuration. Because the internal reinforcing structures shown in Figs. 1-4 have different reinforcing properties along different axes, different ones thereof may be used in different parts of the bicycle frame, depending upon the directions in which the frame needs reinforcing or stiffening.
  • each of the tubes shown in Figs. 1-4 has a septimated interior structure in which one or more inner walls or inner wall segments partition the interior of the tube into a plurality of elongated chambers having longitudinal axes that are generally parallel to one another.
  • Another of these common features is that all of intersections between the inner wall segments and between the wall segments and the tube are free of separately cured joints and therefore preserve the desired continuity of the tube structure.
  • tubes which include internal reinforcing structures which take the form of closed, generally polygonal spars In Fig. 5 this closed polygonal spar includes four secantially disposed inner wall segments 14-5 through 20-5 which together form a square. In Fig. 6, the internal reinforcing structure includes three generally secantially disposed inner wall segments 14-6 through 18-6 which together form an equilateral triangle. Except for the spar-like configuration of their internal reinforcing structures, the tubes shown in Figs. 5 and 6 are generally similar to the tubes shown in Figs. 1-4, and the remarks made in connection with the latter figures will be understood to be equally applicable to the tubes shown in Figs. 5 and 6.
  • Figs. 7, 8 and 9 there are shown internally reinforced tubes which have a non-circular shape.
  • Fig. 7, shows a tube 10-7 having an outer wall 12-7 which forms a square and is internally reinforced by a plurality of inner wall segments 14-7 through 20-7 which have a cross-shaped configuration.
  • Fig. 8 shows a tube 10-8 having an outer wall 12-8 which forms a triangle and is internally reinforced by three inner wall segments 14-8 through 18-8 which have a Y-shaped or star-like configuration.
  • Fig. 9 shows a tube 10-9 having an outer wall 12-9 which forms a hexagon and is internally reinforced by three inner wall segments 14-9 through 18-9 which have a Y- shaped configuration.
  • Tubes which have the latter shapes, but which include internal reinforcing structures that have the spar-like configuration shown in Figs. 5 and 6, may also be built using the method of the invention, but are not shown herein because of their similarity to tubes which are shown herein. It will be understood that the tubes shown in Figs. 7-9 have the same common features discussed previously in connection with the tubes of Figs. 1-4.
  • tubes which include an internal reinforcing structure having at least one internal passage with a longitudinal axis that is aligned with the longitudinal axis of the tube.
  • Fig. 10 shows a tube 10-10 having an outer wall 12-10 which is internally reinforced by an off-center reinforcing structure that has three round internal passages 22-10, 24-10 and 26-10 formed within a thick monohthic reinforcing body 40-10.
  • Fig. 11 shows a tube 10-11 which is internally reinforced by a thick symmetrically distributed reinforcing body 40-11 that has three round internal passages 22-11, 24-11 and 26-11 formed therein.
  • Fig. 10-10 shows a tube 10-10 having an outer wall 12-10 which is internally reinforced by an off-center reinforcing structure that has three round internal passages 22-10, 24-10 and 26-10 formed within a thick monohthic reinforcing body 40-10.
  • Fig. 11 shows a tube 10-11 which is internally reinforced by a thick symmetrically distributed reinforcing body 40-11 that has three round internal passage
  • FIG. 12 shows a tube 10-12 having an outer wall 12-12 which is internally reinforced by a reinforcing structure that includes a concentrically disposed tube 22-12 supported by three radially disposed inner wall segments 14-12, 16-12 and 18-12. It will be understood that the tubes shown in Figs. 10-12 have the same common features discussed earlier in connection with the tubes of Figs. 1-4.
  • Step 1 shown in Fig. 13A, comprises providing a plurality of heat expandable mandrels 50-1 and 50-2 which have semi-circular cross-sections that are similar to the semicircular cross-sections of the elongated chambers 13-1 and 13-2 which separate inner wall 14-1 and outer wall 12-1 of the tube of Fig. 1. More particularly, mandrels 50-1 and 50-2 each have a rounded outward facing surface and a generally planar inward facing surface.
  • mandrels 50-1 and 50-2 are rounded or bevelled so that their use produces the fillets that are shown at the upper and lower ends of inner wall 14-1 of Fig. 1.
  • mandrels 50-1 and 50-2 are composed of a silicone rubber material which expands when heated.
  • a silicone rubber material which expands when heated.
  • One example of a commercially available material of this type is sold under the name "Tooling Elastomer SG Base” by Dow Corning.
  • These silicone mandrels are formed by curing the silicone base material in a mold having a molding cavity with a size and shape dependent upon the size and shape of the elongated chambers to be formed in the tube with which they will be used. Because the molding process used to produce silicone mandrels is known to those skilled in the art, it will not be described in detail herein.
  • mandrels 50-1 and 50- 2 are individually wrapped with layers 52-1 and 52-2, respectively, of a suitable composite material, i.e., a material that includes an array of filaments that has been pre-impregnated with a suitable curable resin.
  • a suitable composite material i.e., a material that includes an array of filaments that has been pre-impregnated with a suitable curable resin.
  • Thin planar pieces of this material commonly known as "prepregs” may include filaments of any of a number of different materials such as graphite, fiberglass, etc.. These filaments are usually formed either into a linear array, commonly known as a unidirectional tape, or into a woven array, commonly known as an isotropic cloth.
  • prepregs are commercially available in a form in which they have been pre-impregnated with a suitable, curable resin, usually an epoxy resin, which allows them to be handled as discrete self-adherent units.
  • a suitable, curable resin usually an epoxy resin
  • One example of a commercially available prepreg materials which is suitable for use in the method of the invention is that sold under the trade designation "Prepreg Fiberite 7714".
  • the latter prepregs are impregnated with a curable epoxy resin that cures at a temperature of approximately 250°.
  • unidirectional and isotropic prepregs may be applied interchangeably, or in combination, and with any desired orientation, depending upon the strength properties which the finished tube is to have.
  • the mandrels may, for example, be wrapped by applying partially overlapping layers of unidirectional tape and/or by applying fully overlapping layers of isotropic cloth, either or both of which may have any desired orientation with respect to longitudinal axis of the mandrel. It will be understood that all such wrapping configurations are within the contemplation of the method of the
  • This step comprises the forming of the individually wrapped mandrels into an assembled multi-part body 53-1, as shown in Fig. 13B, which body has a shape generally similar to that of the desired finished tube. Assembled body 53-1 may at this time be handled as a unit because the stickiness of the resin with which the prepregs are impregnated tends to hold together both the layers with which the mandrels are wrapped and the wrapped mandrels.
  • Fig. 13C there is shown the next step of the method of the invention.
  • This step comprises the overwrapping of assembled body 53-1 with a plurality of layers 54-1 of prepregs of the same type used in underlying layers 52-1 and 52-2 to form the overwrapped assembled body 55-1 shown in Fig. 13C.
  • the prepregs of overwrap layers 54-1 may be of either the unidirectional or isotropic types, or any desired combination thereof, and may have any desired orientation depending upon the strength properties which the finished tube is to have.
  • overwrapped assembled body 55-1 is relatively self-adherent and may be handled as a unit.
  • body 55-1 includes mandrels 50-1 and 50-2 which have been individually wrapped with two layers of prepregs 52-1 and 52-2, respectively, making a total of four layers available for curing into inner wall 14-1.
  • the individually wrapped and assembled mandrels (body 53-1) are collectively overwrapped by four layers of prepregs 54-1, making a total of six layers for curing into outer wall 12-1.
  • the thickness of the walls of the internal reinforcing structure may be approximately equal to that of the tube wall, as shown in Figs. 2, 4, and 7-9, or may thinner than that of the tube wall, as shown in Figs. 3, 5 and 6, simply by selecting appropriate relative values for the numbers of layers in each of these parts of the tube. It will be understood that all combinations of relative thicknesses are within the contemplation of the method of the invention.
  • mold 60 that is used in the performance of the next steps of the method of the invention.
  • mold 60 includes mold segments 60-1 and 60-2 which together define an internal molding cavity 62 within which overwrapped assembled body 55-1 is positioned.
  • This molding cavity preferably has a shape and a size which, taking into account the thermal expansion and contraction which it will undergo during curing, will yield a finished tube having the desired size and shape.
  • mandrels 50-1 and 50-2 expand isotropically. Part of this expansion is directed outwardly and serves to compress the layers of curing prepregs at the periphery of body 55-1 against the unyielding surface of molding cavity 62 and thereby form the wall of the tube. Part of this expansion is directed also inwardly and serves to compress the layers of curing prepregs in the interior of body 55-1 against one another and thereby form the inner walls of the tube. As this occurs, curing proceeds simultaneously in all parts of body 55-1, i.e., all parts of body 55-1 are co-cured.
  • a tube constructed in accordance with the present invention is free of all separately cured joints.
  • the cured body is allowed to cool somewhat and then removed from mold 60.
  • the highest temperature at which the cured body may be removed from the mold depends on the type of curable resin used, but will in general not require that the cured body be retained within the mold until the temperature of both the body and the mold have fallen to room temperature. It will be understood that all combinations of cooling time and temperature which produce a finished product having the desired structure and properties are within the contemplation of the method of the invention.
  • Fig. 13E there is shown the next step of the method of the invention.
  • This step comprises allowing the now consolidated, cured tube and the mandrels located therein to cool to a temperature low enough that the mandrels contract sufficiently to be individually pulled out of the elongated chambers formed thereby.
  • the newly cured tube is ready for final processing.
  • This final processing will typically include the trimming off of any flash formed during the curing process, the grinding and polishing of the exterior of the tube in a centerless grinder or the like, and such additional surfaces finishing steps as are necessary to prepare the tube for incorporation into a bicycle frame.
  • An oblique view of a finally finished tube is shown in Fig. 13F.
  • Figs. 14A through 14F there are shown the steps used in producing an internally reinforced tube with the relatively more complex internal reinforcing structure of the tube shown in Fig. 6.
  • the method illustrated in Fig. 14 begins with the step of providing a plurality of preformed mandrels, each mandrel having a cross-sectional shape which is similar to that of a respective one of the elongated chambers that are to appear within the tube.
  • these mandrels include a centrally disposed generally triangular mandrel 70-1 and three peripherally disposed arcuate mandrels 72-1, 72-2 and 72-3.
  • Each of these mandrels may have the composition and be made in the same way as the mandrels described in connection with Fig. 13.
  • the next steps in the making of tube 10-6 include the individual wrapping of mandrels 70-1 and 72-1 through 72-3 with a plurality of layers of prepregs 74-1 through 74-4, respectively, and the assembly of the wrapped mandrels into the assembled multi-part body 53-6.
  • assembled body 53-6 is then overwrapped with a plurality of layers 54-6 of prepregs, of the same type used to wrap the individual mandrels, to form an overwrapped assembled body 55-6.
  • Overwrapped body 55-6 may then be placed in curing mold 60, as shown in Fig. 14D, and maintained at the previously mentioned curing temperature until the curing process is completed. Thereafter, once the cured tube is cooled and removed from the mold, the mandrels may be removed therefrom as shown in Fig. 14E to produce the tube 10-6 shown in Fig. 14F.
  • the reinforcing structure shown in Fig. 14 includes a mandrel that is surrounded on all sides by inner walls, it lends itself to fabrication by a variant of the method of the invention which uses a mandrel that is not of the heat expandable type. More particularly, the reinforced tube shown in Figs. 6 and 14 may be made with a non-expandable, incompressible mandrel in place of expandable mandrel 70-1. If such an incompressible mandrel is used in practicing the method of the invention, it is inserted between individually wrapped mandrels 72-1, 72-2 and 72-3 at the time of their assembly into assembled body 53-6.
  • Fig. 15 there are shown the steps used in making a tube having the internal reinforcing structure shown in Fig. 10.
  • the steps used in the method illustrated in Fig. 15 are generally similar to those described in connection with Figs. 13 and 14, except in two respects.
  • the first of these is that the tube shown in Fig. 10 includes an internal reinforcing structure having a plurality of relatively small passages 22-10 through 26-10 therethrough.
  • the second of these is that these passages are located in a reinforcing structure 40-10 which is relatively massive or thick and which is offset from the longitudinal axis of the tube.
  • the tube shown in Fig. 10 may be constructed by the method of the invention by including therein an additional step which makes provision for the relatively massive nature of the internal reinforcing structure.
  • the making of the tube shown in Fig. 10 begins in the same manner as making of the tubes shown in Figs. 1 and 6: by the provision of a plurality of heat expandable mandrels 80-1 through 80-4 having cross sectional shapes which are similar to those of the elongated chambers to be formed thereby, as shown in Fig. 15A. These mandrels are then individually wrapped and formed into an assembled multi-part body 53-10, as shown in Fig. 15B.
  • the fitting of the individually wrapped mandrels into an assembled body causes relatively large open spaces to appear at the boundaries between the wrapped mandrels.
  • the method of the invention shown in Fig. 15 includes the additional step of filhng these open spaces individually with sets of build-out strips 82-1 through 82-6 of prepreg, as shown in Fig. 15B.
  • step of including build-out strips in the assembled multi-part body has been described in connection with the filling of open spaces, it may also be used to create additional structures or thickness gradients along or across any desired part of the tube or its internal reinforcing structure.
  • additional structures are locally thickened outer wall regions, such as offset region 40-10 of Fig. 10.
  • Two such regions 42-10 and 44-10 are shown in dotted fines in Fig. 10.
  • Thinner versions of the latter region may be constructed at any desired places on the inner surface of the tube by placing a suitable number of build-out strips over the part of the assembled multi-part body that is adjacent to the region to be thickened. Because of the compressibility of the expandable mandrels, and the incompressibility of the external mold, these thickened regions will extend inwardly from any surface to which they are applied.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • General Engineering & Computer Science (AREA)
  • Moulding By Coating Moulds (AREA)

Abstract

On décrit un procédé qui permet de fabriquer un tube (10-10) à renforcement interne utilisé pour construire des cadres de bicyclettes du type à tubes et fourreaux de fourches. Ce procédé consiste à prendre plusieurs mandrins (80-1) thermo-extensibles dont les formes correspondent à la configuration souhaitée pour la structure de renforcement interne du tube (10-10), à envelopper séparément ces mandrins (80-1) avec un matériau composite (82-1 - 82-6) durcissable à chaud, à emballer ces mandrins enveloppés (53-10) dans un corps à plusieurs parties (55-10), à revêtir ce corps avec un matériau composite (54-10) durcissable à chaud, et à faire durcir ce corps revêtu (60) jusqu'à ce que toutes les parties du matériau composite soient durcies. Après durcissement et refroidissement, on retire les mandrins (80-1) du corps durci pour obtenir un tube (10-10) en matériau composite construit d'un seul tenant avec sa structure de renforcement interne (12-10).
PCT/US1995/012430 1994-09-20 1995-09-20 Procede de fabrication de tubes en materiaux composites a renforcement interne WO1996009159A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US30912594A 1994-09-20 1994-09-20
US08/309,125 1994-09-20

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WO1996009159A1 true WO1996009159A1 (fr) 1996-03-28

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Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2879496A1 (fr) * 2004-12-16 2006-06-23 Eurocopter France Procede et dispositif de fabrication d'une carene de rotor d'helicoptere, et carene obtenue
EP1862293A1 (fr) * 2006-06-02 2007-12-05 ISE Innomotive Systems Europe GmbH Profilé creux et méthode pour sa fabrication
EP2028092A1 (fr) * 2007-08-23 2009-02-25 Yuan Min An Enterprise Co., Ltd. Cadre arrière pour bicyclette
EP2108576A1 (fr) * 2008-04-10 2009-10-14 Yuan Min An Enterprise Co., Ltd. Cadre supérieur de fourche avant pour bicyclette
EP2108578A1 (fr) * 2008-04-10 2009-10-14 Yuan Min An Enterprise Co., Ltd. Fourche avant pour bicyclette
CN102101230A (zh) * 2011-01-14 2011-06-22 元大金属实业（深圳）有限公司 一种车架管的制造方法及车架管
EP2474464A1 (fr) * 2011-01-10 2012-07-11 J.D Components Co., Ltd. Procédé de fabrication d'un tuyau de cadre et structure du tuyau de cadre ainsi fabriquée
WO2015116058A1 (fr) * 2014-01-29 2015-08-06 Sikorsky Aircraft Corporation Mandrin amovible de longeron composite
CN107166160A (zh) * 2017-07-24 2017-09-15 南京圣旗智能科技有限公司 多功能型材及型材组件
FR3059929A1 (fr) * 2016-12-08 2018-06-15 Airbus Operations Procede de fabrication additive d'un tube et tube obtenu a partir du procede
EP3587063A4 (fr) * 2017-09-07 2020-04-22 Kawasaki Jukogyo Kabushiki Kaisha Matrice de moulage pour fabrication de produit moulé en matériau composite, et procédé de fabrication de produit moulé en matériau composite
US11034113B2 (en) 2014-01-29 2021-06-15 Sikorsky Aircraft Corporation Method of assembling a composite spar removable mandrel
WO2023012474A1 (fr) * 2021-08-03 2023-02-09 Composite Braiding Ltd Structure tubulaire composite
US11795993B2 (en) 2021-03-23 2023-10-24 Hamilton Sundstrand Corporation Buckling resistant composite shaft and method of making a buckling resistant composite shaft

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US5472653A (en) * 1992-12-25 1995-12-05 Nippon Oil Co., Ltd. Method for producing carbon fiber-reinforced plastic molding

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1676775A1 (fr) * 2004-12-16 2006-07-05 Eurocopter Procédé et dispositif de fabrication d'une carène de rotor d'hélicoptère, et carène obtenue
US7676923B2 (en) 2004-12-16 2010-03-16 Eurocopter Method and apparatus for manufacturing a helicopter rotor fairing, and a fairing obtained thereby
FR2879496A1 (fr) * 2004-12-16 2006-06-23 Eurocopter France Procede et dispositif de fabrication d'une carene de rotor d'helicoptere, et carene obtenue
EP1862293A1 (fr) * 2006-06-02 2007-12-05 ISE Innomotive Systems Europe GmbH Profilé creux et méthode pour sa fabrication
EP2017067A1 (fr) * 2006-06-02 2009-01-21 ISE Automotive GmbH Elément de formage
EP2028092A1 (fr) * 2007-08-23 2009-02-25 Yuan Min An Enterprise Co., Ltd. Cadre arrière pour bicyclette
EP2108576A1 (fr) * 2008-04-10 2009-10-14 Yuan Min An Enterprise Co., Ltd. Cadre supérieur de fourche avant pour bicyclette
EP2108578A1 (fr) * 2008-04-10 2009-10-14 Yuan Min An Enterprise Co., Ltd. Fourche avant pour bicyclette
EP2474464A1 (fr) * 2011-01-10 2012-07-11 J.D Components Co., Ltd. Procédé de fabrication d'un tuyau de cadre et structure du tuyau de cadre ainsi fabriquée
CN102101230A (zh) * 2011-01-14 2011-06-22 元大金属实业（深圳）有限公司 一种车架管的制造方法及车架管
WO2015116058A1 (fr) * 2014-01-29 2015-08-06 Sikorsky Aircraft Corporation Mandrin amovible de longeron composite
US11034113B2 (en) 2014-01-29 2021-06-15 Sikorsky Aircraft Corporation Method of assembling a composite spar removable mandrel
FR3059929A1 (fr) * 2016-12-08 2018-06-15 Airbus Operations Procede de fabrication additive d'un tube et tube obtenu a partir du procede
CN107166160A (zh) * 2017-07-24 2017-09-15 南京圣旗智能科技有限公司 多功能型材及型材组件
EP3587063A4 (fr) * 2017-09-07 2020-04-22 Kawasaki Jukogyo Kabushiki Kaisha Matrice de moulage pour fabrication de produit moulé en matériau composite, et procédé de fabrication de produit moulé en matériau composite
US11795993B2 (en) 2021-03-23 2023-10-24 Hamilton Sundstrand Corporation Buckling resistant composite shaft and method of making a buckling resistant composite shaft
WO2023012474A1 (fr) * 2021-08-03 2023-02-09 Composite Braiding Ltd Structure tubulaire composite

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