GB2051304A - Fibre-reinforced composite shaft with metallic connector sleeves - Google Patents

Abstract

A tubular fibre reinforced composite shaft integrally incorporates a metal sleeve 14 or connection at the end. Initially a metal sleeve having radially outwardly projecting pointed pins 26 is positioned upon a segment of a mandrel. Fibrous material bearing a non-solidified resinous material is applied around the mandrel and around the pins of the sleeve. The resinous material next is solidified to form a tubular composite shaft whereby a secure torsion-transmitting connection is made with the sleeve, and the mandrel is removed. <IMAGE>

Description

SPECIFICATION Fiber reinforced composite shaft with metallic connector sleeves mounted by mechanical interlock This invention relates to fiber reinforced composite shafts and, more especially, to vehicle drive shafts comprising a fiber reinforced resinous shaft body with metallic coupling sleeves mounted at the ends thereof.

Tubular fiber reinforced composites have been heretofore proposed, as demonstrated by U.S.

Patent Nos. 2,882,072 issued to Noland on April 14, 1959, and 3,661,670 issued to Pierpont on May 9, 1972, and in British patent No. 1,356,393 issued on June 12, 1 974. In the Pierpont patent, for example, it has been proposed to form such composites from a resinous material which is reinforced by glass fibers. In particular, filaments bearing a non-hardened resinous material (i.e., an uncured thermosetting resin) are wound around a mandrel until the desired thickness has been established. The reinforcing fibers can be positioned within the wall of the tubular composite in varying angular relationships.

Thereafter, the resinous material is solidified (i.e. is cured). A premolded threaded end portion can be mounted at the ends of the tubular composite, such as by the winding of filaments directly around the end portion during the winding process.

It recently has been proposed to form vehicle drive shafts from tubular fiber reinforced composites, as demonstrated by U.S. Patent No.

4,041,599 issued to Smith on August 1 6, 1977, and published Japanese Application No.

52-127542, entitled "Carbon Fiber Drive Shaft" which claims priority for the filing of U.S. Serial No. 676,856 on April 14, 1976 of Gordon Peter Worgan et al (now United States Patent No.

4,089,190). In the Japanese application filaments bearing a non-hardened resinous material (e.g., an uncured thermosetting resin) are wound around a mandrel until the desired thickness has been established, whereupon the resinous material is cured. Zones or layers are positioned circumferentially within the wall of the shaft in the specific angular relationships there disclosed.

The above-mentioned Smith patent proposes the attachment of a carbon fiber reinforced epoxy drive shaft directly to a universal joint extension by a specific bonding technique.

Fiber reinforced composite shafts exhibit advantages over metallic shafts, i.e., they are lighter in weight, more resistant to corrosion, stronger, and more inert.

In copending application Serial No. 890,232 filed March 27, 1 978 of Derek N. Yates and David B. Rezin entitled "Improved Carbon Fiber Reinforced Composite Drive Shaft", a fiber reinforced composite drive shaft is disclosed which exhibits improved service characteristics and the necessary strength and durability to withstand the various stresses encountered during vehicle operation. The disclosure of that copending application is herein incorporated by reference as if set forth at length.

Since direct welding or bonding of a resin shaft to metal does not normally create a sufficiently strong and durable connection on a consistent and reliable basis, the use of metallic connector sleeves mounted at the ends of the shaft in accordance with the concept of the present invention provides a means for accomplishing a secure welded connection similar to that utilized with conventional metallic shafts.

The high torque loads which are to be transmitted by a vehicle drive shaft require that an extremely strong and durable torsional drive connection be established between the sleeves and shaft body. Previous proposals for mounting sleeves by employing adhesives or by wrapping the filament bundles around circumferential grooves on the sleeve periphery, cannot be relied upon to provide a connection of the requisite strength and durability.

It is, therefore, an object of the present invention to provide a novel, fiber reinforced resin shaft which minimizes or obviates problems of the types discussed above.

It is an additional object of the invention to provide a novel, fiber reinforced resin shaft suitable for use as a drive shaft in a vehicle power train.

It is a further object of the invention to provide novel methods and apparatus for securing metal connector sleeves to the ends of fiber reinforced resin shafts to enable the shafts to transmit high torsional loads.

BRIEF SUMMARY OF A PREFERRED EMBODIMENT OF THE INVENTION The objects of the present invention are achieved by a tubular fiber reinforced composite shaft, and a method for making same, wherein the shaft body comprises a plurality of integrally bonded circumferential plies of solidified fiber reinforced resinous material. A metal sleeve is mounted in at least one end of the shaft body. A plurality of substantially pointed pins project radially outwardly from the sleeve. The pins are encompassed by fiber reinforced resinous material to form a torsion-transmitting connection between the shaft body and the sleeve. The shaft is formed by anchoring the pins in the sleeve, positioning the sleeve on a segment of a mandrel, and applying the fibrous material around the mandrel and sleeves so as to encompass the pins. Thereafter, the resinous material is solidified and the mandrel is removed.

THE DRAWING Other objects and advantages of the present invention will become apparent from the subsequent detailed description of a preferred embodiment thereof in connection with the accompanying drawings in which like numerals designate like elements and in which: Figure 1 is a longitudinal sectional view of a drive shaft formed in accordance with the present invention; Figure 2 is a cross-sectional view of the drive shaft taken along line 2-2 of Figure 1; and Figure 3 is a fragmentary longitudinal sectional view of a sleeve portion of the drive shaft mounted on a mandrel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION A drive shaft 10 according to the present invention comprises a reinforced resin shaft body 12 of cylindrical cross-section, and a metal connector sleeve 14 secured preferably at each end of the shaft body.

The connector sleeve 14 is generally cylindrical and formed of an appropriate metal, such as steel or aluminum for example. The sleeve includes an inner annular surface 1 6 of constant diameter which is substantially contiguous with an inner surface 18 of the shaft body located longitudinally inwardly thereof, as is evident from Figure 1.

The inner end 20 of the sleeve 14 is tapered in a direction extending longitudinally and radially inwardly (Fig. 3) to provide a feather edge 24 for the reception of windings of reinforced resin material as will be discussed.

The sleeve 14 includes a plurality of radially outwardly projecting pins 26. The pins 26 are integral with the cylindrical body of the sleeve and thus are formed of the same metal. Formation of the sleeve and pins can be effected by any suitable technique, such as by stamping, machinery or welding for example.

The pins are preferably arranged in longitudinally extending, circumferentially spaced rows although any suitable arrangement could be employed. Each pin tapers in a radially outward direction and is substantially pointed at its outer tip. The pins are not sharply pointed, but rather are slightly radiused, so as to be blunt and thereby prevent cutting of the fibers during winding. Thus, the tips of the pins are small enough to prevent a fiber from being hung-up thereon. Rather, as fibers forming the body 12 are wound around the sleeve, fibers contacting the pins 26 are displaced to one side thereof and slide radially inwardly along the side of the pin until contacting the surface of the sleeve or previously wound fibers. This assures that the fibers are tightly wound, without becoming hung-up on the pins themselves, as might occur in the case of pins having flat outer surfaces.

During fabrication of a preferred form of the shaft, a pair of connector sleeves 14 is positioned on segments of a cylindrical mandrel 41 in a longitudinally spaced relationship (Fig. 3), as discussed in copending applications Serial Nos.

890,230 and 890,231 of Derek N. Yates and John C. Presta, both filed March 27, 1978 and assigned to the assignee of the present invention. Those copending applications are incorporated herein by reference as if set forth at length. The sleeves engage the mandrel somewhat snugly, but loosely enough to be removable therefrom. An appropriate clamping arrangement holds the sleeves 14 in place. The mandrel is coated with a release substance to resist the adherence thereto of resin or adhesives. Thereafter, the shaft body 12 is formed around both the mandrel and sleeves.

Construction of the shaft body 12 is preferably performed in a manner more fully described in the aforementioned application of Yates and Rezin.

Summarized briefly, layers of fiber reinforced resin-impregnated material are applied preferably in the form of bundles of substantially parallel continuous filaments bearing a non-solidified (i.e., liquid, soft and tacky, or molten) resinous material.

The bundles can be dipped in an uncured liquid thermosetting resin, such as an epoxy resin, oi.d then wound around the mandrel in multiple passes until a layer of desired thickness is established.

Attention is further directed to U.S. Patent Nos.

3,661,670, 3,202,560, and 3,231,442 for additional details concerning possible arrangements for the clamping of sleeves and winding of filament bundles. The disclosures of these patents are incorporated herein by reference as if set forth at length.

The term "layer" as used herein specifies a circumferential zone within the wall of the tubular drive shaft wherein the fibrous reinforcement is disposed in a specific configuration and differs from the adjacent zone(s) with respect to the configuration and/or composition of the fibrous reinforcement. A single layer may include a multiple pass alignment or buildup of fibrous reinforcement in a given configuration. The term layer encompasses an alignment wherein the fibrous reinforcement is disposed therein at both plus and minus a given angle which optionally can be built-up in multiple passes.

The fibers reinforce the thermoset resin matrix to impart necessary properties of strength and durability to the shaft. In this regard, glass fibers (e.g., E-glass or S-glass) and carbon fibers (i.e., either amorphous or graphitic) materials are preferred. The carbon fibers commonly contain at least 90 percent carbon by weight, and preferably at least 95 percent carbon by weight. Additionally preferred carbon fibers have a Young's modulus of elasticity of at least 25 million p.s.i. (e,g., approximately 30 to 60 million p.s.i.).

The piles of filament bundles are wound in various orientation relative to the longitudinal axis of the drive shaft, and can be built-up to different thicknesses, respectively. Preferably, an initial layer of glass fibers is applied at an angle of from +30 to +50 relative to a line parallel to the longitudinal axis of the shaft. Next, a layer of glass fibers is applied at an angle of from 0 to fl 50.

Thereafter, a layer of carbon fibers is applied at an angle of from 0 to +150. Then a layer of glass fibers is applied at about an angle of from about +60 to 900.

Of course the number and composition of layers, as well as their orientation and thickness may vary, depending upon the characteristics desired to be imparted to the shaft Rather than utilizing filament winding (e.g., wet winding or prepreg winding), other tube forming procedures can be employed, such as tube rolling, tape wrapping, or pultrusion, for example. In the former step, comparatively wide sections of resin impregnated tape are precut to patterns, stacked in sequence, and rolled onto the mandrel.

After the layers have been applied, the nonsolidified resin is cured. In this regard, the resin may be of a self-curing type, or may be of a kind which cures in response to being subjected to heat and/or curing agent.

Relating more particularly to the present invention, after the sleeve(s) 14 has been positioned on the mandrel, an initial layer 32 of glass fibers is wound around the mandrel and sleeves at about a +45 degree angle. As they are wound, the fibers contact the pins 26. Due to the tapered shape of the pins, however, the fibers slide downwardly along the sides thereof to the radially inner end of the exposed portion of the pin.

Accordingly, the fibers encompass opposite sides of the pins in such fashion that relative rotational and longitudinal movement between the fibers and sleeve is prevented.

Thereafter, a layer 40 of glass fibers is wound around the layer 32 at about a zero degree angle.

These fibers encompass the pins 26 in a fashion which further resists relative rotational movement between the sleeve and fibers.

Next, a layer 42 of graphite fibers is wound around the layer 40 at about a zero degree angle. These fibers encompass the pins to still further effect a torsion or rotation transmitting connection between the sleeve and fibers. This layer 42 substantially covers the radially outer tips of the pins 26.

Finally, a layer 44 of glass fibers is wound at about a 90 degree angle around the layer 42. This layer 44 assures that the pins 26 are completely covered.

It will be understood that any number of layers can be applied and at various angles and thicknesses, depending upon desired shaft characteristics.

Therafter, the non-solidified resin is cured to bond the layers together to form an integral composite, and the shaft is removed from the mandrel.

The shaft 10 is ideally suited for use as a vehicle drive shaft. In this connection the pins 26 serve to mechanically lock the shaft body and sleeve together and prevent relative rotational and longitudinal movement therebetween. The pins 26 exhibit a high degree of shear strength capable of withstanding the high torque loadings occurring during the transmission of drive power in a vehicle.

As illustrated in Figure 1 an axially outer portion 36 of the sleeve 14 is exposed, preferably by removing portions of the layers.

The sleeves 14 facilitate connection of the shaft to metal components such as metal yokes in a vehicle power train, since direct metal-to-metal contact is possible.

Although not necessary, it might be desirable to apply an adhesive between the sleeve 14 and the initial layer 32 of fibrous material to augment the connection therebetween.

Although the mechanical lock concept of the present invention is disclosed in conjunction with a particular shaft body, it is to be understood that this concept has utility with composite shafts in general wherein fibrous reinforcement is present in a resinous matrix material.

Although the invention has been described in connection with a preferred embodiment thereof, it will be appreciated by those skilled in the art that additions, modifications, substitutions and deletions not specifically described may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (11)

1. A method of forming a tubular, fiberreinforced composite shaft comprising the steps of: providing a metal sleeve having a plurality of substantially pointed pins extending radially outwardly therefrom; positioning said metal sleeve upon a segment of a mandrel; applying fibrous material bearing a non solidified resinous material upon said mandrel and sleeve and in encompassing relation around said pins; solidifying said resinous material to create a torsion-transmitting connection with said metal sleeve; and removing said mandrel.

2. A method according to claim 1, wherein the application of said fibrous material terminates short of a longitudinally outer end of said sleeve to expose the latter.

3. A method according to claim 1 or 2, wherein said applying step comprises applying a plurality of layers of fibers, with the fibers of at least some of said layers being oriented at mutually different angles relative to the longitudinal direction of the shaft.

4. A method according to claim 1,2 or 3 wherein said applying step comprises completely covering said pins by said fibers.

5. A method according to any of claims 1 to 4 wherein the pins are conically shaped, formed integral with said sleeve, and project therefrom, in circumferentially and longitudinally spaced relationship.

6. A method of forming a tubular, fiberreinforced composite shaft substantially as hereinbefore described with reference to the accompanying drawings.

7. A tubular fiber-reinforced composite shaft comprising a shaft body comprising a plurality of integrally bonded circumferential plies of solidified fiber reinforced resinous material; a metal sleeve mounted in at least one end of said shaft body; and a plurality of substantially pointed metal pins connected to and projecting outwardly from said sleeve; said pins encompassed by fiber-reinforced resinous material of said shaft body to form a torsion-transmitting connection between said sleeve and said shaft body.

8. A shaft according to claim 7, wherein said pins are of conical configuration.

9. A shaft according to claim 7 or 8, wherein a longitudinally outer portion of said sleeve projects from said shaft body.

10. A shaft according to claim 7, 8 or 9 wherein said shaft body comprises a plurality of layers of fibers with at least some of said layers being oriented at mutually different angles relative to the longitudinal direction of the shaft.

11. A tubular reinforced composite shaft substantially as hereinbefore described with reference to the accompanying drawings.