Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Layered – stratified traversely of length – or multiphase...
Reexamination Certificate
2000-04-07
2001-07-03
Tentoni, Leo B. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Layered, stratified traversely of length, or multiphase...
C065S442000, C065S475000, C065S480000
Reexamination Certificate
active
06254816
ABSTRACT:
The invention concerns a process and apparatus for the manufacture of a composite fibrous strand of glass fibers and at least one additive fibrous material other than glass fibers. The apparatus possesses a rotating pick-up surface, a fiber lifting arrangement, a spinning funnel which in its circumferential wall possesses a longitudinal feed connection with a first feed path for glass fibers, a removal opening, a removal device, and a supply device for the additive fibrous material. In addition, the invention concerns a process for the manufacture of a composite fibrous strand of glass fibers and at least one additive fibrous material, and in which process a multiplicity of glass fibers are conducted into a substantially rotationally symmetric zone which is closed in at least its circumferential direction except for the feed connection, in which zone the fibers are subjected to a vortex from which the resulting combined fibers are withdrawn as a fiber composite. Finally, the invention concerns a fiber composite of staple fibers comprising glass fibers and additive material fibers such as plastic fibers (e.g., synthetic polymeric fibers).
BACKGROUND OF THE INVENTION
An apparatus and a process of this general type is disclosed in German Offenlegungsschrift No. 3634904 A1. In that patent disclosure molten glass emerges from nozzles on the underside of glass melting tanks. The molten drops which are thus formed are pulled into glass fibers as the drops migrate to a steeply slanted plane surface, are passed to the surface of a pick-up drum, and are subsequently removed from the drum. Before reaching a full circumferential winding on the drum, the fibers are raised from the drum surface by a lifting arrangement. The fibers next with the aid of a transporting air stream from the drum surface are guided into a spinning funnel wherein the fibers are simultaneously injected and entwined. The glass fiber composite so produced is extracted from an exit opening of the spinning funnel by a withdrawal apparatus. In addition an introduction device for fibers of another material is possible, which additionally introduces fibers of synthetic material to the drum surface. Alternatively, the insertion of the synthetic fibers can take place at the pick-up point for the glass fibers, that is in between the lift from the drum and the entry into the spinning funnel. The fibers of both types always are intermixed prior to introduction into the spinning funnel. This kind of manufacture permits the production of mixed fiber composites from glass fibers and an additive fibrous material, preferably plastic, such as a polyamide. In any event, it has been determined that these fibrous composites do not exhibit a satisfactory homogenous character. Nests of glass fibers and nests of the additive fibrous materials, each in their respective original states, are found to occur in groupings within the fiber composite. Nevertheless, this product is acceptable for many end uses and the tensile strength tends to be maintained.
European Patent No. 0616055 B1 discloses an apparatus and a process for the production of a composite yarn, in which endless glass filaments are combined with continuous filaments of a thermoplastic polymeric material. In this case, the individual glass filaments are led over a coating arrangement. The pretreated polymeric fibers are then, in common with the glass fibers, conducted over a tension roll and subsequently are spun. It should be pointed out that the fiber composite, when observed in cross-section is relatively non-homogenous.
SUMMARY OF THE INVENTION
An apparatus is provided for forming a composite fibrous strand comprising glass fibers and at least one additive fibrous material having enhanced homogeneity, the apparatus comprising a rotating surface for transporting the glass fibers; a device for lifting the glass fibers from the rotating surface; a spinning funnel having a circumferential wall having a longitudinal opening into which glass fibers are introduced along a first feed path, the spinning funnel having and exit opening at an end thereof for removing product; a feeding system defining a second feed path for introducing into the spinning funnel the additive fibrous material, the second feed path being separate from the first feed path when introduced into the spinning funnel; and a device for removing the resulting composite fibrous material formed in the spinning funnel.
A process is provided for the manufacture of composite fibrous strand wherein glass fibers and an additive fibrous material are introduced separately into a substantially rotationally symmetric zone with the zone being closed circumferentially except for a longitudinal introduction locale wherein the glass fibers and the additive fibers are subjected to a vortex to form a composite fibrous strand of enhanced homogeneity, and withdrawing the resulting composite fibrous strand from the zone.
A composite fiber strand formed from staple fibers comprising a homogeneous admixture of glass fibers and at least one additive fibrous material in a weight ratio of 10:90 to 99:1.
The present invention has the objective of making of a hybrid yarn which is better suited for use as uniform fibrous material during the formation of a flat preform laminate.
This objective is achieved by an apparatus as described earlier wherein the supply device possesses a second feed path, which is separated from the said first feed path at the circumferential wall of the spinning funnel. With this equipment, it is possible to create a fiber composite that is homogeneous.
A previously known apparatus is modified and is used for the manufacture of the composite fibrous strand. The apparatus is modified so that a different feed location is provided for the additive fibrous material. In the past the premise was that the two fiber types were to be already intermixed prior to their introduction into the spinning funnel. For instance, on the drum pick-up surface the glass fibers and the additive fiber were to be already mixed thereby providing a mixed material which is introduced into the spinning funnel. It now has been found through empirical research that this premise was not accurate when optimum results are sought. Possibly the difficulty lies in the fact that the plastic fibers cannot penetrate the air stream layer which picks up the glass fibers on the drum surface and in which the glass fibers are caused to float. Giving credence to this viewpoint in the previously known procedure a full admixture between the glass fibers and the plastic fibers does not come about. When, however, the second feed path is employed as in the present invention, in order to feed the additive fibrous material into the spinning funnel, there is no need that the mix has already occurred prior to introduction such as on the drum surface. The mixing is now brought about entirely in the spinning funnel in a homogeneous manner. Besides achieving homogeneity, this procedure also has the advantage that the danger of contamination in the immediate environment by the additive fibrous material is considerably less. The input air stream carrying the additive fibrous material also lends itself more easily to adjustment. Moreover, a flat material which is produced from the improved homogenous composite fibrous strand just described, can be worked using a lesser press time so that a finished composite article can be made more quickly and at a lower cost. With the greater homogeneity a favorable notch impact strength, structural strength and the like can be obtained as well as an improved flexural strength. By that is meant, a mechanical strength in addition to mere tensile strength is made possible when using the hybrid yarn when forming flat, preformed, or molded parts. The glass fibers, in the press procedures consolidate more easily into the matrix of the additive fibrous materials.
Advantageously, the respective first and second feedpaths run through the feed connection and are separated from one another by a partition.
In relation to a conventional apparatus, only a
Dosch Reinhart
Klaus Michaela
Mann Hans Georg
Burns Doane Swecker & Mathis L.L.P.
Schuller GmbH
Tentoni Leo B.
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