Apparatus for manufacturing composite tubular articles

Abstract

A frame, a drive mechanism for rotating a mandrel, at least two spindles mounted to the frame, a tensioner, and a belt extending between the first and second spindles may be used to roll pre-preg strips or similar sheets of composite materials around the mandrel. The belt over the spindles, and the spindles guide the belt through changes in its direction of travel. The mandrel is mounted in the drive mechanism in contact with the belt, which changes its direction of travel around the mandrel. The lower surface of the belt bears against portions of the spindles, and the mandrel contacts the upper surface of the belt. As the drive mechanism rotates the mandrel, pre-preg sheets are fed between the mandrel and the belt and are thereby wrapped around the mandrel. The belt presses the pre-preg sheets against the mandrel. The wrapped mandrel may then be removed from the apparatus and cured in any suitable manner known in the art to produce a composite tubular article.

Description

BACKGROUND OF THE INVENTIONThe present invention relates generally to methods and machines for manufacturing composite tubular articles such as golf club shafts and the like.Composite articles comprise reinforcing fibers embedded in a matrix. Graphite, boron, glass KEVLAR and other fibers are well-known. Epoxy is a well-known matrix. The fibers may be aggregated in woven textiles or in strips or sheets in which the fibers are uniaxial, i.e., unidirectionally aligned. Strips impregnated with epoxy resin are commonly known as "pre-preg" strips. To manufacture a composite article, pre-preg are laid upon or wrapped around a form or bonding tool in multiple plies. Although, to a certain extent, the somewhat tacky resin adheres the pre-preg strips to the bonding tool, the strips quickly begin to separate from the bonding tool, particularly if the tool is non-planar or contoured. Separation of the pre-preg from the bonding tool will not only result in a composite article that is aesthetica...

AI Technical Summary

Benefits of technology

In the exemplary embodiment, the belt is not a continuous loop; rather, the ends of the belt are connected to the tensioner. Nevertheless, in certain embodiments, the belt may be continuous. The tensioner may comprise any suitable device or devices for maintaining tension in the belt relative to the first and second spindles. In the exemplary embodiment, the tensioner comprises resilient cords that connect the ends of the belt to each other and further comprises a third spindle. The belt and cords pass around the three spindles, and the third spindle is selectably movable toward and away from the first and second spindles to release and apply tension, respectively. Moving the third spindle to the position in which the belt is relaxed facilitates insertion and removal of the mandrel. In certain other embodiments, however, the tensioner may comprise other types of resilient members or other types of movable spindles. For example, although in the exemplary embodiment the movable spindle portion of the tensioner comprises a third spindle and a mechanism that moves the third spindle toward and away from the first and second spindles, in other embodiments a movable spindle type of tensioner may comprise mechanisms for moving any one or more of the spindles with respect to other spindles. The mechanisms may include a mechanical actuator, such as a pneumatic cylinder and/or may include a resilient m

Problems solved by technology

Although, to a certain extent, the somewhat tacky resin adheres the pre-preg strips to the bonding tool, the strips quickly begin to separate from the bonding tool, particularly if the tool is non-planar or contoured.

Separation of the pre-preg from the bonding tool will not only result in a composite article that is aesthetically undesirable because it does not correspond to the contours of the bonding tool, but will also result in structural defects in the article.

Although the above-described process is adequate for fabricating tubular composite articles having uniform tapers, the planar platens cannot roll pre-preg strips tightly against the surface of a mandrel having a non-uniform taper or other complex contours.

Nevertheless, the rubber pads do not exert a sufficiently uniform pressure against the mandrel; more pressure is exerted on sections of the mandrel having greater diameters than is exerted on sections of the mandrel having smaller diameters.

Nevertheless, a uniform pressure cannot be exerted against a mandrel having a diameter that changes over a distance less than the width of a single key-like section.

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