The present invention relates to a guide plate for
slivers as defined in the preamble of appended Claim
1.
In feed devices for combing machines, the web of
textile fibres to be combed, or the sliver, as it is
conventionally called, is unrolled from a reel by
means of rotating grooved rollers and extends across
the guide plate as far as the oscillating nipper
structure which comprises a feed roll and from which
the sliver passes to the actual combing machine.
As it passes from the grooved rollers to the feed
roll, the sliver must always be kept under slight
tension. This requirement is hampered, however, by
the fact that, in order to carry out the combing
operation, together with the detaching rollers and
with the rotary comb of the combing machine, the
nipper structure performs an oscillatory movement.
As a result, the length of the path which the sliver
has to follow varies continuously between a minimum
value and a maximum value.
For the supply system to operate well, the advance
of the sliver must be as smooth and uniform as
possible, irrespective of the aforementioned
oscillatory motion which, however, tends to cause
stoppages and breakage of the sliver because of
insufficient or excessive tension.
As described in the publication EP 0409775, it has
been proposed to form the guide plate as a single
piece of plastics material connected, on the one
hand, to the oscillating nipper structure and, on
the other hand, to the frame of the machine close to
the unrolling roller of the sliver feed unit. The
plate has a reduced thickness along a bend line
perpendicular to the direction of sliding of the
sliver so that, in practice, it is constituted by
two portions which move relative to one another as
if they were joined by a hinge. This solution has
been found to be quite critical with regard to the
selection of the material and is not always
satisfactory with regard to the uniformity of the
tensioning of the sliver.
The object of the present invention is to provide a
guide plate for slivers which enables the tension of
the sliver to be kept uniform and is of simple and
reliable construction.
This object is achieved by the provision of a guide
plate for slivers as defined and characterized in
Claim 1.
Further characteristics, as well as the advantages
of the guide plate according to the invention will
become clear from the description of two preferred
embodiments given by way of non-limiting example,
with reference to the appended drawings, in which:
Figures 1 and 2 are a schematic side view of a feed
device for combing machines which incorporates a
guide plate for slivers according to the invention,
in two different stages of operation, Figures 3 and 4 are schematic side views of a device
similar to that of Figures 1 and 2 in two different
stages of operation, the device incorporating a
different version of the guide plate for slivers
according to the invention, and Figure 5 shows a detail of a variant of the system
for connecting the sliver guide-plate according to
the invention to the frame of the machine.
In the drawings, a sliver feed device, generally
indicated 1, is associated with an oscillating
Ripper structure 2 in a combing machine, not shown.
In Figures 1 and 2, the device 1 comprises a feed
unit with a grooved roller 3 which rotates so as to
unroll from a reel 20 a sliver 4 to be combed.
The grooved roller 3 rotates about an axis which is
fixed relative to the frame of the device 1, not
shown, which in turn is fixed to the frame of the
machine.
The device 1 also comprises a guide plate 5 which is
associated with the nipper structure 2 and is
arranged to guide the sliver 4 to be combed, which
is advancing towards a feed roller 6 of the
oscillating nipper structure 2.
The guide plate 5 is substantially right-angled in
shape and comprises a first, substantially
quadrangular portion which is arranged horizontally
and receives, on its upper face, the sliver from the
grooved roller 3.
In the present embodiment, the first portion 7 is
fixed to the frame of the feed device 1 and is
constituted by a metal plate made of stainless
steel, advantageously rendered smooth by polishing
on its upper face.
The guide plate 5 also comprises a second portion 8
which is also substantially quadrangular, is
arranged in a transverse position relative to the
first portion 7, and supplies the sliver to the feed
roller 6 of the nipper structure 2.
The plate 5 also comprises a rounded, bent portion
9 disposed in an intermediate position relative to
the first and second portions 7, 8, to complete the
right-angled shape. It has a convex part 10 over
which the sliver 4 slides before passing over the
second portion 8.
The second portion 8 has a lower end 11 by which it
is articulated to the oscillating Ripper structure
2, close to the feed roller 6.
Opposite the lower end 11, the second portion 8 also
has an upper end 12 by which it is rigidly connected
to the bent portion 9, defining therewith a curved
sliding surface for the sliver, the second portion
8 being movable and guided by guide means fixed to
the frame.
In this embodiment, the bent portion 9 and the
second portion 8 are formed in a single piece by a
single, suitably-bent metal plate, preferably made
of stainless steel and advantageously polished on
the bent sliding surface.
The guide means comprise at least one connecting
rod. In this embodiment, there are two identical
connecting rods, of which only one, indicated 30,
is visible in the drawings, and which are fixed for
pivoting on the frame of the machine at one end and
on the two opposite sides of the portion 8, at the
same distance from the axis of articulation to the
Ripper structure 2, at the opposite end. The
position in which the connecting rods 30 are
connected along the sides of the portion 8, that is,
the position of the axis of rotation 13, is selected
so as to take account of the movement of the Ripper
structure 2 so that the path of the sliver 4 between
the grooved roller 3 and the feed roll 6 is
substantially constant during the operation of the
machine.
As is known, the oscillating nipper structure
performs a complex oscillatory motion since one end
21 thereof is restrained on the frame so as to
describe an arc about a first point 22 on the frame
and its opposite end 23 is restrained so as to
describe an arc about a second point 24 on the
frame. As a result of the connections described
above, the plate 5 has one end, the lower end 11 of
the second portion 8, which follows the motion of
the nipper structure 2.
It can be seen that the intermediate bending point
on the portion 9 where the sliver changes direction
is always at a substantially constant distance from
the feed roll 6 (Figure 1, compared with Figure 2)
during the movement of the nipper structure 2.
Similarly, the distance between the bent portion 9
and the grooved roller 3 remains substantially
constant, even though the portion 9 has a free end
14 which describes an arc in space. Owing to the
bending, this free end does not interfere with the
motion of the sliver 4 which rises and falls,
accompanied by the end 14, whilst the first portion
7 helps to guide it.
A second embodiment of the guide plate according to
the invention is described below with reference to
Figures 3 and 4 with the use of the same reference
numerals for identical or equivalent parts.
In this embodiment the device 1 again comprises a
feed unit with a grooved roller 3 which rotates so
as to unroll from a reel 20 a sliver 4 to be combed.
The grooved roller 3 rotates about an axis which is
fixed relative to a frame of the device 1, not
shown, which in turn is fixed to the frame of the
machine.
The device 1 also comprises a guide plate 5 which is
associated with the Ripper structure 2 and is
arranged to guide the sliver 4 to be combed which is
advancing towards a feed roller 6 of the oscillating
Ripper structure 2.
The guide plate 5 is of a substantially right-angled
shape and comprises a first, substantially
quadrangular portion 7 which is arranged
horizontally, receives the sliver from the grooved
roller 3, and, advantageously, is polished on its
upper face to facilitate the passage of the sliver
4.
The guide plate 5 also comprises a second portion 8
which is also substantially quadrangular, is
arranged in a position substantially perpendicular
to the first portion 7, and supplies the sliver to
the feed roll 6 of the nipper structure 2.
The plate 5 also comprises a rounded, bent portion
9 which is in an intermediate position relative to
the first and second portions 7, 8 to complete the
right-angled shape. It has a convex part 10 over
which the sliver 4 slides before passing over the
second portion 8.
The second portion 8 has a lower end 11 by which it
is articulated to the oscillating nipper structure
2 close to the supply roll 6.
The second portion 8 also has an upper end 12 by
which it is connected rigidly to the bent portion 9.
The first portion 7 is also connected rigidly to the
bent portion 9 on the opposite side.
In comparison with the previously-described
embodiment, the portion 9 and the second portion 8
define for the sliver a curved sliding surface which
also comprises the first portion 7.
The first portion 7, the bent portion 9 and the
second portion 8 are preferably formed in one piece
by a suitably-bent metal plate made of stainless
steel, advantageously polished on the curved sliding
surface.
The bent portion 9 and hence the entire plate 5 is
restrained on the frame of the machine by means of
at least one connecting rod. In this embodiment
again, there are two identical rods 30 fixed
pivotably to the two opposite sides of the portion
8 at the same distance from the axis of articulation
to the Ripper structure 2. The position in which
the connecting rods 30 are fixed is selected by the
same criterion as in the embodiment described with
reference to Figures 1 and 2.
In this embodiment, the intermediate bending point
on the portion 9 where the sliver changes direction
is also always at a substantially constant distance
from the feed roller 6 (Figure 3 compared with
Figure 4) during the movement of the nipper
structure 2.
Similarly, the distance between the bent portion 9
and the grooved roller 3 remains substantially
constant, even though the first portion 7 has a free
end 15 which describes an arc in space.
Owing to the bending, the free end 15 does not
interfere with the movement of the sliver 4 which
rises and falls alternately in operation whilst the
first portion 7 helps to guide the sliver 4.
Preferably, in this embodiment of the guide plate 5,
described with reference to Figures 3 and 4, an
angle of no less than 70° and no more than 90° is
included between the first portion 7 and the second
portion 8.
According to the variant shown in Figure 5, the
guide means of the portion 8 of the plate 5 are
constituted by two pins 13' (only one of which is
visible in the drawing) which are fixed laterally to
the upper end of the portion 8, and by two slots 50
formed in respective plates 51 fixed to the frame
and defining a track for the pins 13'. The slots 50
may define a straight track, as shown in the
drawing, or may be shaped so as to define an arcuate
track. To enable the guide means to be adjusted to
the best position, suitable means, of known type,
not shown, may be provided for fixing the plates 51
to the frame in an adjustable manner.
In addition to the advantages mentioned above, the
guide plate according to the invention is
structurally simple, is easy to fit and maintain and
can be produced at low cost. Moreover, it is
substantially immune to wear since it does not have
parts which are subject to deformation or bending in
operation.
In order to satisfy further and contingent
requirements, an expert in the art may apply to the
guide plate for slivers according to the invention
many further modifications and variations all of
which, however, are included within the scope of
protection of the present invention defined by the
appended claims.