Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including interlaminar mechanical fastener
Patent
1990-10-29
1993-09-07
Bell, James J.
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including interlaminar mechanical fastener
139 11, 139384R, 428257, D03D 300
Patent
active
052427455
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a spiral-shaped textile structure comprising warp yarns across which are passed successive rows of weft yarn. It also relates to a process for weaving a spiral-shaped textile structure and a machine for weaving such a structure.
There exist numerous fields in industry which require the use of spiral-shaped fabrics or textile structures. Mention can be made especially of the manufacture of composite pieces of revolution, especially of a wheel, a cone, or a truncated cone type, in particular for pieces intended to be used with a great speed of rotation, such as turbines or compressors, and also of the manufacture of joint type pieces.
In order to make such structures, use was at first considered of pieces of fabric obtained, in a conventional manner, in rectilinear strips. Cutting a spiral shape of such pieces of fabric involves numerous trimmings which increases the cost, all the more since certain pieces of fabric are made of costly materials.
In order to avoid these losses, and to improve the orientation of the fibers, spiral-shaped pieces of fabric have been made using a conventional weaving technique. According to this technique, the warp yarns coming from upstream of the weaving machine are drawn by a tapered take-up roller. The contact surface of this roller with the fabric is a truncated cone, the generating line of which is essentially equal to the width of the fabric. The warp yarns are arranged according to helices having the same axis. The rows of weft yarns are arranged according to the radii of the circles formed by the warp yarns. Upstream of the tapered roller, a comb is positioned, which, after each passage of the weft-threader, brings the weft yarn which has just been inserted into the warp yarns closer against the other weft yarns already woven. These latter, together with the warp yarns, form the fabric which has the form of annular turns.
These pieces of fabric do not have a satisfactory structure.
In fact, the rows of weft yarns extend over the entire width of the fabric. Since they are arranged according to the radii, the separation between two successive rows of weft yarns increases moving away from the inner radius towards the outer radius of the turns of the fabric. This leads to a great variation in the content of fiber in the fabric, which is accentuated all the more with greater the curvature and width of the fabric.
Such spiral-shaped fabrics obtained by means of conventional techniques can therefore not be used in applications which require fabrics which have an essentially uniform fiber density.
A number of techniques were then proposed in order to improve the filling of spiral-shaped fabrics and to render uniform the density of yarn in these fabrics.
By way of illustration, the patent FR-2 490 687 can be cited, which relates to a fabric in a strip of the type comprising warp yarns across which are passed successive rows of weft yarn, the warp yarns being essentially arranged in helices having the same axis, so that the fabric forms superimposed annular turns centered on the axis, the rows of weft yarn being orthogonal to the warp yarns.
In order to improve the filling of the weaving, it is proposed to no longer unwind the weft yarn from the inner radius to the outer radius of the fabric, but to organize the weaving in such a manner that more weft yarns are unwound in those parts of the fabric situated on the side of the outer radius.
This patent advocates delimiting, in the width of the fabric, a plurality of contiguous sections. Each section comprises a number of warp yarns and can be woven independently by virtue of an independent device for selection of the yarns. A weaving plan is defined, which indicates the set of sections to be woven upon each unwinding of the weft needle. Each row of weft yarns thus extends over a set of contiguous sections which is defined so as to provide, in each section crossed by a row of weft yarns, the points of tying corresponding to the weave selected for the fabric and to obtain a predetermined filling of the
Aucagne Jean
Martinet Laurent
Bell James J.
Brochier S.A.
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