Method and device for spreading fiber strands

Abstract

A method and a device for spreading a fiber strand to provide a strip-type fiber strand. In particular, the initial fiber strand is provided with an initial width and thickness, and is then spread to form the strip-type fiber strand having a greater final width and a smaller final thickness as compared to the initial width and thickness. The fiber strand consists of continuous multifilament fibers.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a national phase application pursuant to 35 U.S.C. 371 of International Application No. PCT / EP2015 / 055689, filed Mar. 18, 2015, which claims priority to German Application No. 10 2014 105 464.4, filed Apr. 16, 2014. These applications are hereby incorporated by reference in their entireties.FIELD OF THE INVENTION[0002]The invention relates to a method and a device for spreading of a fiber strand, which features an initial width and an initial thickness, to a strip-type fiber strand with greater final width and with smaller final thickness, wherein the fiber strand consists of continuous multifilament fibers.BACKGROUND OF THE INVENTION[0003]The spreading of fiber strands has long been known and is employed on fiber strands made of polymer fibers to improve physical properties, since due to the spreading, twisting of the filaments in the fiber strand, for example, can be eliminated and a fiber strand with filaments posit...

AI Technical Summary

Benefits of technology

[0017]In an advantageous manner, the method according to the invention represents a low-cost method since the fiber strand is processed when dry, no energy is required for dewatering, heating or drying of the fiber strand. Moreover, the nature of the fiber strand does not change with respect to its composition, namely the quantity ratio of multifilament fibers and release agent in the method. A strip-type fiber strand with consistent and larger final width, and with a lesser final thickness is obtained according to the desired specification, which leads to the desired, low surface weight and, when using the fiber strand for fabric or textile, results in lighter composites with consistently good mechanical properties, such as tensile strength, for instance.

[0018]A device is used for this method which comprises an unwinding unit for the fiber strand to be spread, a spreader station for spreading of the used fiber strand into a strip-type fiber strand, a controllable tensioning device for consistent tensioning of the fiber strand during its movement through the spreader station, and a winding device for the spread, strip-type fiber strand. In the manner according to the invention, the spreader station contains at least one sonotrode for contacting and spreading of the fiber strand, wherein the sonotrode introduces vibrations at a frequency of between 15 kHz and 80 kHz from its contact surface from above and/or from below (z-direction) into the fiber strand, which causes a spreading of the fiber strand in the y-direction. In this respect, two or three sonotrodes in sequence will have a favorable effect on the fiber strand. The more sonotrodes contained in the spreader station, the better is the spreading result, but the apparatus will also become more expensive. For this reason, spreader stations with two to three sonotrodes are preferred. The ultrasound vibrators are equipped prefe

Problems solved by technology

This kind of spreading method is energy-intensive and can only be used on fiber strands that are electrically conductive and can thus be electrically charged.

This release agent adheres to the fibers and in this blown method, impedes a uniform spreading of the fiber strand.

Moreover, a removal of the release agent is difficult, since firstly, release agents with different properties are used, and secondly, these release agents prevent the damaging [sic], e.g. of fragile carbon fibers during subsequent processing.

A method of this kind is very difficult to control and results in irregular final widths of the fiber strand.

But the disadvantage of this method is that the release agent surrounding the filaments changes in the water bath.

Depending on the nature of the release agent, this can also result in a ch

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