The invention is concerned with a method of manufacturing a loom shuttle
and a shuttle made by this method.
In looms it is usual to draw the weft between the beam threads by
means of control belts of bendable and flexible material and clips fastened to
those. The control belts, which here are called shuttles, are foreseen with a perforation
and the alternating movement of the shuttles between the beam threads are carried
out with break wheels coupled to these holes.
The abrasion strength, the rigidity and the dimension stability are
among the most important properties of the shuttles. The alternating movement of
the shuttle against the guides and break wheels cause abrasion and an exact movement
of the shuttle requires a high rigidity.
Nowadays the shuttles are made of reinforced plastic by using the
so-called prepreg-method. In this technique prepeg-plates are made by impregnation
of the reinforcing fibers with resin and by precuring. The precured prepregs are
cut in right form and set onto each other between the form halves and hot pressed
in connection with which step the resin is cured. In the after-treatment stages
bands of wished breadth is sawed from the prepreg-plates which are perforated by
punctioning and the bands are cut in their final form.
From the above presented facts it appears that the preparation technique
of today includes many stages and that it has many disadvantages. In the first
hand the method requires much work and this method is not possible to carry out
continuously. With this method it is possible to make shuttles of only one thickness
from the same plate and a flexible changing of the cross section of the form is
not possible. Furthermore, it is difficult to achieve reinforcing fibers of sufficient
concentrations with the prepreg-method, why it is difficult to achieve sufficient
strength and rigidity properties.
An object of the invention is to provide a method to prepare a shuttle
without the above-presented disadvantages. According to the invention the shuttle
can be prepared in the form of a continuous band with a wished thickness and cross
section form and higher concentrations of the reinforcing fibers, a better orientation
of the fibers and better properties of the fatigue durability can be achieved.
The method of the invention for making a shuttle to a loom, which
shuttle, possibly foreseen with a necessary perforation, consists of a composite
structure of reinforcing fibers bound by matrix resin, is characterized in that
the shuttle is prepared in the form of a continuous band, that is uniform in the
longitudinal and transversal directions, by drawing continuous reinforcing fibers
treated with current matrix resin, possibly including discontinuous fibers that
give abrasion strength properties, through a form structure, the form and dimensions
of the inner surface of which correspond to the wished cross section of the shuttle
and curing of the matrix resin occurs at the same time.
According to the invention the shuttle is prepared directly with its
final cross section form continuously in form of a band that is continuous in the
longitudinal direction. By drawing reinforcing fibers treated with currently resin
through the form construction, it gives at the same time, as the resin is curing,
such a form to the cross section of the band that is exact all over the length
of the band. By changning the form construction a flexible changing to products
with another cross section can be carried out. In this way a continuous process
is achieved and ready fabrics for the shuttles can be cut from a continuous band
with the wished form for the cross section.
The invention is also concerned with a shuttle for a loom that is
prepared with the above-described method. According to an advantageous embodiment
of the invention the reinforcing fibers are fibers of thermoplast. The break elongation
of the thermoplastic fibers are higher than that of the usually used glass fibers
and thus the using of reinforcing fibers is possible also in the surface layers
of the band, where the extension strain and compressing stress are the highest,
when the band is bended. Furthermore the use of thermoplast fibers improves the
abrasion properties of the shuttle.
The thermoplastic fibers in the shuttle of the invention can advantageously
be for example of polyester, polyamide, polyethene, polypropene or polyacrylnitrile.
In the method of the invention it is however possible to use any organic or inorganic
fibers that can be bound to a composite structure by means of resin.
According to an advantageous embodiment of the invention also powder
or interrupted short fiber can be mixed with the plastic matrix to improve the
abrasion properties. An advantageous break-fiber for this purpose is aramide fiber
pulp or polytetrafluorethene fiber.
The matrix used for bounding of the reinforcing fibers can for instance
be of polyester resin or of polyolefine thermoplastic.
The reinforcing fibers are according to an advantageous embodiment
of the invention of the same kind of material as the resin used for bounding of
the reinforcing fibers. Thus, with the method of the invention, the polyester fibers
can be bound by polyester resin.
Furthermore the shuttle of the invention may contain special fibers
for regulation of the tensile strength, compressing stress and the longitudinal
thermal expansion. Thus it is possible to use carbon fibers inside the band to
regulate said properties. Still further, it is possible to regulate the transversal
strength properties so that a part of the reinforcement fibers is in woven form
whereat the beam threads improve the transversal strength.
The invention is illustrated in the following with reference to the
enclosed figures in which
- Fig. 1 presents schematically an apparatus to carry out the method of the invention
- Figs 2 and 3 present the construction of a shuttle according to the invention.
In Fig. 1 the apparatus for preparation of the shuttle of the invention
has been presented with reference number 10. In the launder 11 there is current
uncured resin 12. Inside the resin 12 there is a roll 13 around which reinforcing
fibers 13 are led from coils 15 whereat the fibers will be wet by resin 12. The
wet fibers 16 are led from the launder 11 over a guide roll 17 to a curing form
18 in which the resin is cured and a continuous shuttle fabricate 19 with composite
structure is formed with the wished form for the cross section. The shuttle fabricate
19 is drawn continuously forward by means of drive belts 21 that runs around drive
rolls 20 or with corresponding driving devices. After that shuttles of wished length
can be cut from the ready shuttle fabricate band for after treatment purposes,
e.g. perforation. If it is wished to make shuttle fabricates with another cross
section the curing form 18 can easily be changed.
Fig. 2 presents the construction of the shuttle according to the invention.
The reference number 22 presents uniform reinforcing fibers running in the longitudinal
direction of the shuttle band which are bound by matrix resin 23. The carbon fibers
24 run in the middle of the band by means of which fibers the thermal expansion
of the product can be regulated. The transversal reinforcing fibers have been marked
with the reference number 25 which can be formed for example when the reinforcing
fibers at least partially are in the form of a woven product.
In Fig. 3 there has furthermore been presented breaked fibers 26 in
form of aramide pulp that improve the abrasion strength of the product. The breaked
fibers can be added for example to the resin 12 in the launder 11.
The invention is concerned with a method of preparing a shuttle to
a loom and a shuttle prepared by the method. The shuttle consists of a composite
structure of reinforcing fibers bound by matrix resin, and it is possibly foreseen
with a necessary perforation. The shuttle is prepared in the form of a continuous
band that is uniform in the longitudinal and transversal directions by drawing
continuous reinforcing fibers treated with matrix resin, possibly including discontinuous
fibers that give abrasion strength properties, through the form structure and the
form and dimensions of the inner surface of the form corresponds to the wished
cross section of the shuttle and curing of the matrix resin (23) occurs at the