[0001] This invention relates to a rotary spiral element which operates as a yarn guide
and as a compensator and twister element in depositing sliver cross-windings on a
forming bobbin by means of a winding carriage in a gill box or derived machine. In
the description given hereinafter and in the claims the term "sliver" will be used
throughout to indicate a textile fibre roving, a textile fibre sliver or any other
aggregate of textile fibres. In a gill box with a sliver collection on bobbins of
conventional type, the package is built up by winding the sliver on an idle roller,
rotated by one or more fluted rollers, by means of a false twist device arranged to
give the sliver roundness and strength and to allow individuality in subsequent unwinding.
[0002] It is well known to the sliver in being conveyed between the exit calender unit of
the gill box and the winding system must be subjected to the necessary collection
tension to form a compact bobbin. The winding must therefore be effected with the
sliver fibres as condensed as possible so that the cohesion between the fibres does
not allow false draft to arise in that part of the sliver between its exit from the
gill bos and its deposition on the surface of the forming bobbin. The sliver leaving
the calender unit is often fragile, as its constituent fibres are short or held together
with little twist. The sliver is also subjected to a cyclic variation in distance
between the fixed point of exit from the calendar unit of the gill box and the mobile
winding yarn guide driven with a to-and-fro movement along the forming bobbin. This
variation in the collection distance must not result in a silver tension which changes
the dimensional and quality characteristics of the sliver between the calender exit
and the point in which the winding operation occurs. Relatively large tension variations
could also lead to sliver breakage. It is also clear that a breakage of this kind
interrupts the production process and requires the assistance of service personnel.
[0003] The labor cost of such emergency assistance is a considerable factor in calculating
the production costs. Various solutions have already been proposed to overcome this
winding problem. In US patent 3,670,978 it is proposed for example to pass the sliver
through an intermediate guide ring mounted between the exit of the gill box calender
unit and the winding system in a manner mobile such that the sum of the distance between
the ring and the calender exit and the distance between the ring and the sliver guide
is always constant. Different systems based on the same principle have also been proposed
and constructed, comprising for example toggle joint levers or similar elements able
to form the desired linkage. However, these solutions all have drawbacks in that they
involve the reciprocating movement of relatively large masses, and cannot be applied
to current high-speed machines, not only because of the large amount of energy involved
and the rapid wear of the various members, but also because vibration and consequent
fatigue failures can occur. Many attempts have been made by the present applicant
to ensure a sliver bobbin winding which is as uniform as possible. A typical example
of these practical attempts by the present applicant is described in Italian patent
application No. 88200983.0. The spiral element described in said application works
well compared with devices already proposed in the art, however its operation could
be improved. In this respect, its application has not been found perfectly satisfactory
in that when certain types of sliver are used it results in non-uniform twisting because
of the intricate guiding of the sliver along the fixed turns of the spiral element.
This effect, even if very limited, is undesirable because it ruins the appearance
of the sliver and in addition can initiate false draft which influences the strength
of the collected sliver during its unwinding in the next processing stage.
[0004] In the light of this and of the aforesaid defects and drawbacks of the arrangements
of the current art, the object of the present invention is to provide a rotary spiral
twister element for the winding carriage of a gill box which is able to guide the
sliver while simultaneously compensating said distance variation by the insertion
of a large number of twists which make it resistant and elastic during the entire
cross-winding so that said rotary spiral element does not suffer from aforesaid drawbacks
of known devices. To this end, according to the invention the applicant has designed,
experimented with and perfected a rotary spiral element for inserting twist and compensation
into textile fibre slivers, consisting of a tube or wire of spring steel or other
wear-resistant material wound helically with its pitch and number of turns dependent
on the type and weight of the material to be worked. As the rotary spiral element
is simply a steel wire or tube, it has minimum inertia and therefore does not substantially
affect the rapid movement reversals of the winding carriage. The rotary spiral inserts
a large number of twists deriving partly from the twisting action of its helix turns
and partly from its rotation about itself. This provides the necessary binding and
compactness to the sliver fibres to ensure that the sliver acts elastically when under
tension during the cross-winding operation. More specifically, the rotary spiral guides
the sliver to its collection on the surface of the forming bobbin while simultaneously
giving the sliver a twist extending in direction back to the calender unit. Said twist
which extends along the portion upstream of the spiral as far as the exit from the
calender unit is more concentrated along those sliver portions of lesser cross-section,
so making up for their lesser strength than the other portions of greater cross-section.
As is apparent, this makes the strength uniform along the entire sliver and eliminates
portions of low torsional strength which can easily undergo breakage to result in
interruption to the production process, with some of the aforesaid consequences.
[0005] The twist inserted into the sliver at its exit from the calender unit by means of
the rotary spiral therefore advantageously keeps the component fibres of the sliver
bound together and enables it to be tensioned by elastic elongation to provide perfect
compensation for the distance variation without the danger of creating false draft.
[0006] Because of the simplicity and lightness of the rotary spiral, the machine collection
rate can be substantially increased and the machine cost considerably reduced. The
rotation of the helix about itself contributes to substantial improvement in the twist
of the collected sliver and results in its perfect roundness. In this respect, after
much experimental work the applicant has found that rotating the spiral yarn guide
element about its axis results in twist which is propagated in a uniformly distributed
manner to consequently provide consistency to the cross-section of the fibre sliver
under continuous winding, so eliminating so-called "marrying", ie the adhesion together
of flat fibres to create imperfections during the next production process stage involving
the unwinding of the bobbin. These and further advantages are all attained by the
improved tensioning element for a winding carriage, according to the present invention,
comprising a yarn guide spiral which rotates rapidly about its axis while being moved
transversely to-and-fro parallel to the axis of the drive roller. Said spiral yarn
guide rotates in one direction and then in the other as a consequence of its linkage
to the alternating direction of motion involved in the said transverse to-and-fro
movement.
[0007] According to one embodiment, the spiral yarn guide comprises a spiral rotating in
a single direction independently of the alternating direction of motion involved in
the said transverse to-and-fro movement. According to a further embodiment, the spriral
yarn guide element comprises helical turns constructed of tube of low weight so as
to provide minimum inertia to the alternating motion and the association rotary movement,
this being particularly useful for high collecting speeds.
[0008] A preferred embodiment of the spiral yarn guide element is described hereinafter
by way of non-limiting example with reference to the single accompanying drawing.
The accompanying drawing shows a diagrammatic side view of a rotary spiral yarn guide
element for inserting twist and providing elastic compensation, according to the invention,
and also showing upstream the calender unit through which the sliver leaves the gill
box, and downstream the cross-winding system for forming the sliver collection bobbin.
On the drawing: 2 is a dashed line schematically indicating the gill box or derived
machine; 1 is the calender unit operating as a feed means for the sliver leaving the
gill box 2; 7 is the presser roll of the calender unit 1, which together with the
roll 8 continuously extracts the fibre sliver 9 from the drafting zone; 9 is the textile
fibre sliver consisting substantially of a more or less numerous aggregate of textile
fibres of varying length; 3 is a rotary spiral in the form of a helical spring with
one or more helixes, having an inner diameter which is positive, or in the limit negative,
and with a turn pitch depending on the type of the fibre and the weight of the sliver
to be worked. Said spiral 3 has two ends, one of which is joined to the rotary bush
6 and the other is fixed to the condensing bush 14; 19 is the plate for connecting
and supporting the device of the present invention to and on the reciprocating movement
mechanism 20 which is guided to move parallel to the axis of the forming bobbin 16;
24 is the bush slidable along the cylindrical guide bar 22 positioned parallel to
the axis 30 of the drive roller 32 for the forming bobbin 16; 26 is the profiled support
plate for the entire device, and driven with reciprocating motion along a transverse
travel path substantially equal to the desired axial length of the bobbin 16; 4 is
the bearing assembly allowing the bush element 6 to rotate about itself while caused
by the reciprocating movement mechanism 20 to continuously move to-and-fro; 5 is
the non-rotating outer casing of the element 6; 18 is the suitably shaped grooved
pulley which by the action of a round belt 12 or similar element and with the cooperation
of the backing surface or guide 15 generates the rotary movement of the element 6
by deriving it from said reciprocating movement; 14 is the condensing bush with an
inner surface of spherical, conical or frusto-conical profile converging in the direction
along which the sliver 9 is collected on the bobbin 16.
[0009] The operating description given hereinafter with reference to the said figure relates
in particular to that which is new and ignores those elements or devices which are
cooperative or complementary during operation, as these are of the known art. The
sliver, roving or fiber aggregate leaving the calender unit 1 is inserted into the
spiral 3 along its axis and is conveyed through the condensing bush 14 to be collected
on the periphery of the bobbin 16 rotating on the winding spindle 28. The twist inserted
both by the rotation of the rotary spiral 3 and by the friction along the inner surface
of the helix turns travels back rapidly and continuously as far as the rolls 7 and
8 to give the sliver that torsional compactness necessary to make it elastic under
the alternate tensioning present in a cross-winding. A preferred embodiment of the
invention has been described herein, however the shape and dimensions of the parts
can be changed, or the wire of the spiral can be other than circular in shape, such
as oval, rectangular or the like, without leaving the scope of the present invention
as claimed hereinafter.
1. A spiral yarn guide element for providing compensation and false twist to a sliver
leaving a gill box and for depositing it in the form of cross-winding on a forming
bobbin by means of a winding carriage, characterised in that it rotates rapidly about
itself while being moved transversely to-and-fro parallel to the axis of the drive
roller.
2. A spiral yarn guide element as claimed in claim 1, characterised in that it rotates
in one direction and then in the other as a consequence of its linkage to the alternating
direction of motion involved in the said transverse to-and-fro movement.
3. A spiral yarn guide element as claimed in claim 1, characterised in that it rotates
in a single direction independently of the alternating direction of motion involved
in the said transverse to-and-fro movement.
4. A spiral yarn guide element as claimed in claim 1 and one or other of the subsequent
claims, characterised in that the helical turns are constructed of tube of low weight
so as to provide minimum inertia to the alternating motion and the associated rotary
movement under high collecting speeds.
