Method for the manufacture of a composite fiber, web, strand or roving

A method for forming composite webs. The method includes introducing alternative fibers during the fiber glass drum or sliver manufacturing process so as to produce a composite web, strand or roving.

FIELD OF THE INVENTION 
The invention relates to the field of manufacture of composite fiber webs 
or strands from glass fibers and fibers or filaments of other materials. 
DESCRIPTION OF RELATED ART 
In the textile industry, the manufacturing methods for composite fiber webs 
or strands are common knowledge (the terms web, roving and strand are used 
interchangeably herein). Accordingly, fibers of different materials and/or 
composition are mixed before the process or at the spinning line. In other 
words, natural fibers are mixed with other natural fibers prior to the 
manufacture of the fiber web, or initially, synthetic fibers or filaments 
are produced and then these are mixed with natural fibers or other 
synthetic fibers prior to web production and then are subsequently worked 
into a fiber web. 
Even in the fiber glass industry, composite fiber webs are produced 
according to this method, since it lends itself well to the manufacture of 
composites since the fiber materials can be ideally balanced with each 
other. An essential element is the fact that glass materials have limited 
elasticity which is improved by the incorporation of synthetic fibers. In 
addition, a frequent reason for the manufacture of composite fiber webs of 
glass fibers and fibers or filaments of other materials, especially 
synthetic fibers and filaments, are restrictions or prohibitions regarding 
the use of asbestos fibers which were introduced in many countries for 
health-political reasons. Glass fibers can be utilized as a replacement 
for asbestos for reasons not discussed in detail here, whereby for one 
version, a mixture of glass fibers and synthetic fibers or filaments was 
shown to be suitable. In the past, such composite fiber products were 
produced according to the methods described for the textile industry, i.e. 
glass fibers were produced separately and mixed with the produced 
synthetic fibers prior to forming into a glass web. 
SUMMARY OF THE INVENTION 
The intent of the invention was to replace the prior art method, which uses 
several work processes (fiber manufacture, mixing and forming), by a 
simpler, more rapidly proceeding method which achieves at least the same 
homogeneity level of the composite fibers. 
The invention consists in having discovered that surprisingly the so-called 
"drum attenuation or sliver method" for the manufacture of glass fibers is 
suitable to mix the glass fibers with the fibers of other materials during 
the manufacture of glass fibers from glass filaments and, immediately 
following, to produce a composite fiber web in the same manner used for 
producing a pure glass fiber web. It is now unnecessary to first produce 
the glass fiber and to mix it with synthetic fibers and then to produce 
from this mixture a glass fiber/synthetic fiber web. Instead, the tried 
and proven method for the manufacture of a glass fiber web in one step 
(i.e., according to German Patent Specification DE-PS No. 825 456) can be 
used for the production of a composite fiber web, whereby the final 
product can be precisely adjusted to the required fiber quantity and 
composition without restricting the glass filament drawing and fiber 
spinning process. 
The use of the known drum attenuation method, in which filaments [4] are 
drawn from the ends of glass rods or from nozzles of a trough [2] 
containing fluid glass with the help of a rotating drawing surface [3] is 
proposed for the manufacture of a composite fiber web of glass fibers and 
fibers of filaments of other materials, especially synthetic fibers. It 
avoids the complications of the known method from the textile industry in 
which glass fibers are first produced and then are mixed with the fibers 
of other materials either prior to processing or during the drawing 
process. The filaments [4] are drawn parallel, next to each other, and 
attenuated to thin filaments, which are then lifted from the circumference 
of the rotating drawing surface before the completion of one wrap around, 
dispersed into fibers and fed into an enclosed space [7]. This space is 
oriented rotation symmetrical and axis parallel to the drawing surface. In 
the enclosed space, a fiber whirl [9] is formed which is drawn off on one 
side as a fiber, whereby fibers or filaments of other materials [22] are 
uniformly added during the operation of the spinning process.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
With the help of a rotating drawing surface [3] in the form of a drum, 
large numbers of parallel, side by side glass filaments [4] are 
continuously drawn from the spinning nozzles [1] of a melting trough [2] 
or from the heat softened ends of glass rods. These contact the drawing 
surface external to the free fall line at [5], are drawn off and 
attenuated to a smaller diameter than at their formation with the help of 
this drawing surface. Prior to the completion of a single wrap around of 
the drawing surface [5] the filaments [4] are lifted by a suitable lifting 
device [6], for instance a stripper of thin sheet metal, or by counter 
directed blast streams, and fed into an enclosed space [7] such as a 
so-called spinning funnel, which is oriented parallel to the rotating 
drawing surface [3]. A co-rotating air cushion is formed around the 
drawing surface [3] by the high rotation velocity. It assists during the 
drawing of the filaments [4] and is also lifted by the removal device [6] 
and fed into the enclosure [7] along with the suspended fibers (8). As a 
result, an air-fiber-vortex [9] is created which forms the fibers in the 
circulating whirl to a fiber web or a roving. It is then continuously 
drawn off through a tubular nozzle [10] by means of a drawing and spooling 
device [11]. The strength of the web is determined by the number of fibers 
and/or the removal rate. The side of the enclosure [7] opposite the nozzle 
[10] is open and allows the rotational wind or the air cushion in the 
funnel to escape. 
The rotating drawing surfce [3] is surrounded over a large portion of its 
circumference at a distance by a mantle [12] which serves as a protective 
device. In addition, it assures that no contaminants are pulled to the 
drawing surface by the resultant rotational wind and that the air cushion 
surrounding the drum is safely guided to the removal location [13]. 
If defects occur at the removal location [13], then a preceeding removal 
device [14] is activated which removes the accumulating filaments from the 
drawing surface [3] until the defects at [13] have been corrected. 
At the beginning of the process described above, and also when the 
filaments break during the production process, a glass droplet [15] is 
formed at the spinning location [1]. It pulls a new filament [4'] behind 
itself during the free fall. The filament is conducted to the drawing 
surface [3] by an oblique guide surface [16] underneath the drum. The 
filament is caught by the drawing surface and is carried along by it. At 
the same time it is separated from the droplet [5]. 
By means of pull wheels [17] or by a pull drum extending over the entire 
width of the drawing surface [3], filaments [18] or a synthetic fiber 
supply in the form of a filament yarn or a roving are drawn from a supply 
location, such as an unspooling device [19]. The filaments [18] or the 
yarn/roving are dispersed or opened up to separate fibers by a traversing 
friction wheel [20] in contact with the pull wheels [17] or the pull drum. 
The fibers then arrive at a drawing and attentuation device [21], such as 
a nozzle, which effects a further disintegration to individual fibers and 
conveys them in the direction of the desired impact and delivery area of 
the drawing surface [3]. 
The synthetic fibers are conveyed to the contact point [5] or the contact 
region of the filaments [4] extending across the drawing surface [3]. 
Accordingly, the synthetic fibers [22] arrive at the contact line of the 
filaments [4] on the drawing surface [3] between the filaments lying next 
to each other as well as on them. The synthetic fibers are then conveyed 
from this surface, together with the filaments [4], by the rotational air 
draft and/or by the air cushion created by the mantle [12] to their 
removal point [13]. Together with the glass fibers created at this point, 
they are then conducted as a glass fiber/synthetic fiber whirl into the 
enclosed space [7] in which they form a composite fiber web. 
The above description makes a clear distinction between the filaments [4] 
drawn from the spinning position [1], which are deposited onto and carried 
along and attenuated by the drawing surface [3] and the fibers [8] created 
by the whirl in the enclosure [7]. In fact, this distinction applies only 
to a more or less large fraction of the fibers. The filaments [4] are in 
actuality not only drawn off and attenuated by the drawing surface [3] but 
are also drawn off and attenuated by the air cushion created by this 
surface, whereas both can be effective for the individual filament during 
its path. A filament can therefore arrive at the drawing surface, then 
become immersed in the air cushion, be deposited again at the drawing 
surface, etc. or the other way around. The filaments are frequently broken 
into longer and shorter pieces by this, so that at [3], longer and shorter 
filament pieces or fibers are present, which additionally contributes to a 
thorough mixing of the glass fibers and the synthetic fibers even before 
entry into the enclosed space [7]. 
By choice of the drawing velocity at [17] and the air velocity of the jet 
[21] different effects can be accomplished. If for instance, the supply of 
the synthetic fibers [22] is at a higher rate than that of the produced 
glass filaments [4], a slight bulging occurs in the produced web. 
The choice of synthetic fibers is not restricted to one material condition 
and can be selected to suit the requirements as well as the quantity. Even 
fine metal fibers or, if necessary, natural fibers and filaments can be 
processed according to the method of the invention. 
Directing the synthetic fibers [22] to the contact location [5] of the 
glass fibers [4] on the drawing surface [3] has the advantage of bringing 
them together early with the filaments and the glass fiber pieces and 
glass fibers produced partially on the drawing surface. However, the 
synthetic fibers can also be introduced at the removal position [13] for 
the glass fibers or at the location between this and the entry into the 
enclosed space [7]. This has the advantage that the synthetic filaments 
are assured not to come in contact and be mixed with glass filaments [4] 
but only with glass fibers 8.