Winding – tensioning – or guiding – Helical or random winding of material – Untwisted fiber bundle
Patent
1999-03-10
2000-12-12
Walsh, Donald P.
Winding, tensioning, or guiding
Helical or random winding of material
Untwisted fiber bundle
2425381, B65H 5402
Patent
active
061586889
DESCRIPTION:
BRIEF SUMMARY
This invention refers to a drive mechanism for transporting a tow at constant speed between feed and receive reels, an interlayer tape being interleaved on both reels between successive windings of the tow.
Driving a tow at constant speed between two reels requires special measures due to the variable spool thickness on the two reels during the tow transfer between the two reels. If a drive motor is directly coupled to the receiving reel, the transfer speed is low at the beginning, as long as the receiving spool is nearly empty, and high at the end, when the receiving spool has a large diameter. Constant transfer speed, however, is an essential requirement, if the tow is to be treated between the two reels, for example by a CVD process (Chemical Vapour Deposition).
Thus, for example, 30-m-long fibre tows constituted by 5000 monofilaments with a filament diameter of about 10 .mu.m have to be conveyed through a CVD chamber of 2.multidot.m length with minimum tangling and without touching the chamber walls.
It could be imagined to control the speed of the driving motor coupled to the receive reel in such a way that the rotation of said reel is controlled as a function of the spool diameter on said wheel. Such a control device, however, is complex, especially if it is to be adapted to various nominal transport speed values, and requires precise detectors for measuring the spool diameter of the receiving reel. The invention aims to render the device more simple and to improve the transport speed accuracy.
This aim is achieved by the fact that the interlayer tape, which is interleaved between successive windings of the tow on both reels for protecting the CVD layers on the tow, is drivingly coupled between the two reels to a drive wheel and that each reel is drivingly coupled to the drive wheel via a slip mechanism.
Thus, the drive wheel is not rigidly connected to one of the reels and is not subjected to a speed adjustment in accordance with the spool diameter of the driven reel. It can be directly coupled to a constant speed drive motor or a step motor.
For items of preferred embodiments of the present invention, reference is made to the secondary claims.
The invention will now be described in more detail by means of a preferred embodiment and the enclosed drawings.
FIG. 1 represents a longitudinal cut view of a CVD chamber including the tow drive mechanism according to the invention.
FIG. 2 shows in an enlarged scale a cut view according to line I--I in FIG. 1 through the axes of the reels and the drive wheel wheel.
FIG. 3 shows schematically characteristic steps of operation of the mechanism according to the invention.
The CVD chamber shown in FIG. 1 comprises a CVD reactor tube 1 having for example a length of 2 meters. The CVD chamber is classical and its details such as heating or cooling means, CVD-agent injection means and pumps are not shown.
This chamber is associated to a drive mechanism unit 2 on the left side and a tensioning device 3 on the right side of the figure. A tow 4, for example 30 meters long, passes twice through the chamber 1 and is supplied and received by two reels 5 and 6 mounted in the drive mechanism unit 2.
The tow can be constituted by an elongate object of any adequate material to be treated in the chamber 1, by individual fibres or by a tow of fibres, this last mentioned application constituting the preferred application case on which the present description is based.
In order to prevent the newly formed coatings on the tow from interacting after the tow has been wound on the receiving reel, a protective tape 7 is interleaved between successive windings of the tow on both reels. As it will be seen hereafter in connection with FIG. 3, this tape does not pass through the chamber 1 and it is unwound from the supply reel during the transport of the tow, and immediately thereafter it is interleaved between successive windings of the treated tow on the receive reel. Between these two reels, it only passes over a drive wheel 9 to which a motor (not shown) supplies a constant speed, as
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Bullock Edward
Dias Antonio
Nagy Endre
European Atomic Energy Community (EURATOM)
Walsh Donald P.
Webb Collin A.
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