[0001] The present invention refers to a device and process for doffing in the ring spinning
frames.
[0002] In industrial practice, the yarn production technique is widely prevalent that includes
a first stage of ring spinning which produces bobbin yarn, followed by a second winding
stage in which the yarn is unwound from its bobbin, cleaned of its defects and rewound
in a package, which contains a much greater yarn quantity and which corresponds to
a considerable number of processed bobbins. The winding processing is much faster
than the spinning, and thus a small quantity of winding stations or units, on the
order of several dozen, is capable of completing the production of a great number
of ring spinning units, on the order of several thousand.
[0003] In general, the ring spinning frame is composed of hundreds of spinning units, arranged
on each of the two machine faces, with a driving, governing and control unit of the
machine placed at one of its ends and with a transport system which serves the two
faces of the machine. The trend towards machines with increasing productivity involves
the increase of the number of units and increasingly longer machines.
[0004] On the spinning frame, the transfer of the bobbins replete with yarn to be sent to
the winder, and the transfer of the empty tubes (on which new bobbins are wound) to
the spinning units generally occurs by individually moving bobbins and tubes in erect
position, for example on pins inserted on longitudinal metal strips which slide on
the faces of the spinning frame or on peg support pins borne by conveyor belts or
strips.
[0005] Still generally, in yarn production, a spinning frame is coupled to a winder having
hourly winding capacity that considerably exceeds the spinning capacity of the spinning
frame, so to complete, with a certain margin, the entire spinning production.
[0006] The spinning process on the ring spinning frame is governed by a governing and control
unit which detects the achievement of the produced meters of yarn in bobbins on every
unit of the spinning frame, stops the spinning according to a procedure which leaves
the yarns in predetermined position and proceeds with the doffing. In brief, the doffing
consists of drawing the finished bobbins from the respective spinning units and unloading
them on the transport system of the spinning frame, and of the subsequent drawing
of the empty tubes from the transport system and positioning them on the ring spinning
units, operating in parallel over all the spinning units which compose the ring spinning
frame. For such purpose, the ring spinning frame is provided with a doffing device
which is capable of lifting itself and simultaneously grasping all the completed bobbins
over all the spinning units which compose the spinning frame, with a series of individual
clamps which are brought to take the bobbins, to lift themselves, taking the bobbins
from the bobbin carrier spindles on which the bobbins are fit, and then lowering themselves
in order to deposit the bobbins on the individual supports which form the transport
system. The same device then provides for taking the empty tubes and fitting them
on the bobbin carrier spindles freed of the bobbins in the previous operation.
[0007] Such operation has considerable problems deriving from the fact that the same doffing
device must simultaneously serve the hundreds of spinning units - currently as many
as 500 on each face - placed over a length of dozens of meters. Bobbins and tubes
must be taken and positioned with respect to the transport pins and to the bobbin
carrier spindles with a precision on the order of millimetres, moving them while taking
into account the bulk and obstacles and exerting forces on the order of a ton in order
to lift the doffing device, the entire face of the completed bobbins and tearing their
yarns bound to the respective spinning units.
[0008] In the prior art, the doffing device uses a clamp carrier bar borne by an extendible
pantograph, capable of positioning, taking and lifting bobbins and tubes from the
bobbin carrier spindles, from the parking stations and from the pins of the underlying
transport system. Such pantograph is made height-extendible between the two above-mentioned
levels, and is also rotatable 15-25° in accordance with an axis parallel to the face
of the machine, in order to avoid the bulk of the spindle carrier rail and the other
members of the spinning units arranged along the face. Parking stations are provided
of the waiting empty tubes; such station can be brought to an intermediate level and
aligned with the spinning spindle or up to the level of the moving belts, though offset
by a half pitch with respect to the spinning spindle of the unloaded bobbin: in both
cases, the movement is complicated by the precision needs of the relative position
of the clamps with respect to the bobbins and the tubes to be moved.
[0009] The present invention is aimed for the doffing of the finished bobbin and its substitution
with an empty tube which simplifies such yarn processing step and makes it more efficient.
[0010] The invention is described here with reference to a typical embodiment thereof in
a ring spinning station.
[0011] The present invention, in its most general meaning as device for bobbin doffing and
substitution, is defined in the first claim. Its variants or preferred embodiments
are defined in the dependent claims 2 - 8.
[0012] The present invention, in its meaning as a process for bobbin doffing and substitution,
is defined in claim 9. Its preferred variants or embodiments are defined in the dependent
claims 10 - 12.
[0013] The characteristics and advantages of the bobbin doffing device and process according
to the present invention is more evident from the exemplifying but non-limiting description
of a typical embodiment thereof, illustrated in the following figures. Figure 1 schematically
shows, in section, a ring spinning group of conventional type, while figure 2 schematically
shows, in section, two spinning units on the two faces of the spinning frame with
their members involved in the doffing operation. Figures 3A and 3B show the doffing
device in front view, respectively in its maximum and minimum elevation positions,
figure 4 shows, in front view, the positions between which the bobbins and tubes are
moved, and figure 5 shows the detail of the extension driving of the clamps engaging
bobbins and tubes.
[0014] For an improved comprehension of the problems and technical solutions connected with
the ring spinning, the conventional scheme is described overall of a spinning unit
with reference to the figures 1 and 2, considering that every spinning frame is composed
of a plurality of spinning stations aligned along its two faces. Every spinning frame
face is composed of hundreds of such stations, which commonly derive their driving
from motors which actuate longitudinal axes, and their functions from dispenser units
which distribute them along the machine. The spinning frame is generally structured
with a sequence of modules of transportable size, composed of a plurality of spinning
stations; such modules are then brought to and assembled on site, so to offer the
complete spinning frame. The modules shown in the figures are typically formed of
twenty-four spinning units for each face.
[0015] The sliver 1 fed to the spinning units comes from a series of packages 2 hung above
the spinning units, and is brought forward to the drafting unit 3. This generally
consists of a plurality of driving members of the sliver at increasing linear speeds;
such driving members gradually refine such sliver by making the fibres composing it
slide between them. The drafting group is depicted in figures 1 and 2, for example,
with three pairs of drafting rollers or cylinders, of which the lower cylinder is
made with a grooved segment of a longitudinal bar, shared with the adjacent spinning
stations and rotating in accordance with the arrow a). The upper cylinder is idle,
made with elastomeric material and is driven into movement in accordance with the
arrow b) by the lower cylinder, on which it is pressed by a support. The final pair
of drafting rollers imparts the final drafting on the sliver, such rollers being driven
at a greater linear speed than that of the preceding roller pairs. At the end of the
drafting group, the sliver has already assumed the size of the yarn 10 and already
receives the twisting from the underlying ring spinning unit.
[0016] The yarn 10 first passes into the thread guides 11, typically of pig's tail form,
and from here to a rotating slider which rotates on a fixed ring 12, with diameter
slightly greater than the bobbin to be produced and borne by a ring-rail 14 shared
with the adjacent spinning units. The ring-rail 14 is continuously moved in accordance
with the arrow c) in two directions, to continuously lift and lower all the fixed
rings 12 of the single spinning units around their bobbins being formed and to distribute
the yarn 10 on the tube 16 of every bobbin 15 being wound. The tube 16 is fit on the
underlying rotating spindle 20 driven into rotation at high speeds, which currently
are in the range of 10,000-20,000 rpm. In general, such driving is carried out with
drive belts 22, which slidingly engage the lower part 21 of the bobbin carrier spindle
20.
[0017] With every rotation of the spindle 20, i.e. of the bobbin 15, the yarn released by
the drafting group 3 is drawn so to be wound on the bobbin 15. Substantially, a twisting
turn of the yarn 10 is generated, which drives in rotation the rotating slider, although
with a slight delay due to its friction with the guide ring 12. If the spindle rotates
at N revolutions per minute and the final cylinders of the drafting group 3 release
L meters per minute of drafted sliver 10, except for shortening due to twisting, the
twists T applied to a meter of produced yarn result equal to N/L.
[0018] The yarn 10 rotates in a whirling manner around the bobbin, forming the so-called
"balloon" due to the centrifugal force. The balloon is due to significant stress on
the yarn 10 and can be limited with a containment ring 18, in general of slightly
greater diameter than the transverse size of the bobbin 15.
[0019] The thread guide 11 is also mounted on a movable platform or rail 13, like the balloon
containment ring 18 which is firmly mounted on a platform or rail 19 thereof, capable
of vertical travel movements which keep them spaced from each other and in any case
above the level of the ring-rail 14. For such purpose, the three rails 14, 13 and
19 are guided with vertical guides 25 on the two faces of the spinning frame and lifted
and lowered with a belt and pulley system 26 which periodically raises and lowers
the three rails, in accordance with predetermined rates.
[0020] The yarn twisting is caused by the rotation of the bobbin 15 and extends, together
with the relative stresses, up to the point at which the sliver of the yarn 10 is
released by the final cylinders of the draft group 3. In order to wind the yarn thus
twisted on the bobbin 15 in a regular manner, as the bobbin progressively forms, it
is necessary to distribute it on the bobbin at different heights, continuously changing
the level of the rotating slider borne by the ring-rail 14, continuously moved in
accordance with the arrow c) in two directions, and modulating the deposit so as to
continuously raise the mid-point of the travel of the arrow c). The deposit of the
yarn 10 on the bobbin 15 generally starts in the lower part of the bobbin and rises
upward in overlapped layers with conical progression, layers obtained with a series
of slow, ascending movements of the ring-rail 14 following by sudden and slightly
shorter descending movements. The object of such bobbin winding method is essentially
that of giving a tapered shape to the bobbin, so that the bobbin results compact,
so that it does not break up during its unwinding, and so that the yarn is unwound,
substantially unwinding layer-by-layer from its upper conical part.
[0021] According to the present invention, the doffing device 30 shown in figures 2 and
3 is achieved with the following modes. The device 30 is provided for moving tubes
and bobbins between the bobbin carrier spindle 20 of each of the spinning units and
a transport device, shown as an example with a service conveyor belt 27 on the two
faces of the spinning frame, on which the pegs 28 circulate, composed of a disc base
and provided with an upper vertical pin on which the empty tube or the finished bobbin
to be transported are fit from time to time, respectively from the winder to the spinning
frame or vice versa. The transport device 27 can also be made as a metal strip which
bears vertical pins fixed thereon.
[0022] Close to and parallel to the conveyor belt 27, for each face of the spinning frame,
a parking station is provided composed of a series of vertical pins 29, one for each
ring spinning unit, which are integral with the fixed structure of the machine. As
said, said positions between which bobbins and tubes are moved are shown in front
view in figure 4.
[0023] The doffing device 30 constitutes a particular feature of the invention and comprises:
- a clamp carrier bar 31 as long as the face of the spinning frame, on which the clamps
32 are borne and mounted for the engagement of the bobbins 15 and the tubes 16 to
be moved. In general, the actual clamp 32 is composed of a rigid cylindrical ring
body having at its interior an annular chamber inflatable with the injection of compressed
air. The transverse size of the inflatable annular chamber is determined in such a
manner that, with non-inflated chamber, it can be easily inserted and removed from
the bobbin 15 or tube 16. The re-inflating with compressed air of the chamber instead
locks the tube and allows raising the tube 16 or bobbin 15 and moving them by exerting
the necessary forces, while the release of the compressed air allows freeing it after
the movement. According to a preferable embodiment of the invention, the clamp 32
is provided for engaging the upper part of the tube 16;
- a series of connection and support arms 34 of the clamps 32 on the clamp carrier bar
31. As illustrated with figure 2 and with figure 5 - which report a planimetric view
of the work positions of the clamps 32
- the arms 34 are composed of bars pivoted on pins 35 on the clamp carrier bar 31 and
can rotate between the various angles of the work positions, in accordance with the
arrows r, approaching or moving away from the face of the machine.
In figures 2 and 5, on the left, the clamps are shown brought to the maximum height
and to the maximum extension for working on the bobbin carrier spindles 20, for taking
the finished bobbin 15 or for placing the empty tube 16; on the right, the clamps
are shown that have been brought to the minimum height and to the minimum extension
for working on the bobbin carrier spindles 20 so to take or place the finished bobbin
15 on one of the vertical parking pins 29. For example, the references A and B indicate
the longitudinal coordinate of two adjacent spinning units A and B on one of the faces
of the machine. The plate 28A bears the bobbin or the tube for the spinning unit A,
the pin 29A serves as parking for the spinning unit A: the spinning, drawing or deposit
positions on the peg 28 on the conveyor belt 27 and parking on the pin 29 result longitudinally
offset in accordance with the rotation r of the arm 34 around its pin 35. The driving
in rotation r of the arms 34 can be made with mechanical, hydraulic or pneumatic command.
In figure 5, a mechanical driving system is shown as an example. It comprises a connection
bar 40 of all the arms 34 which bear the clamps 32 by means of pins 41: this connection
constrains all the arms to coherently rotate in accordance with the axial translation
of the bar 40. At the end of the connection bar 40, a plate 42 is in fact mounted
of circular sector form, which is connected with a pin 43 to the bar 40. The plate
42 is in turn pivoted on the clamp carrier bar 31 with a pin 44, so to make a pantograph
for the approaching/moving away movement of the clamps 32 with respect to the movement
positions in the horizontal plane. For such purpose, the pins 35 and 41 of the arms
34 and the pins 43 and 44 of the plate 42 are mounted at the same distance d from
each other. The driving in rotation around the pin 44 of the plate 42 is achieved,
as an example, by making a toothing 46 on the edge of the circular sector which constitutes
the plate 42, which engages a coherent toothing of a gearmotor 47, with high reduction
ratio; such gearmotor is made to rotate in clockwise/anticlockwise sense for imparting
the alternating rotations in accordance with the arrows r to the plate 42. Alternatively,
the bar 40 can be driven in axial translation with a screw/nut screw system driven
in rotation with a stepping motor in controlled rotation in the two directions.
Alternatively to the modes for bringing the clamps 32 and the relative arms 34 closer
to/further away from the spinning units with rotations (r) described up to now, such
movements can also be achieved by translation, maintaining such arms in fixed and
orthogonal position with respect to the clamp carrier bar 31, providing them with
a slider part which bears the clamp 32 and which is extendible in order to be orthogonally
lengthened and retracted with respect to the spinning units which it must serve. For
example, the extendible part can be made with a rack which is made to advance or retract
in accordance with the rotation of a rotating bar, axially arranged on the bar 31
and provided with toothing which engages the entire toothing of the rack of the clamp
carrier arms;
- a pantograph device 49 for lifting and lowering the clamp carrier bar 31. The pantograph
is composed of a plurality of lifting arms arranged along the faces of the spinning
frame in accordance with a kinematic type that is known in the art. Each of the arms
comprises a pair of support bodies 50 and 51, with one fixed and other slidable along
the longitudinal axis of the spinning frame. In particular, the fixed support 50 bears,
on its upper part, a constraining pin 52 of the connection strut 53 with the lifting
arm 56. The movable support 51 bears, at its interior, a nut screw which engages a
threaded bar 58 and which makes the support body 51 advance towards the right or left
depending on the clockwise/anticlockwise rotation m imparted to the threaded bar 58.
On its upper face, the movable support 51 supports a lower constraining pin 60 of
the lifting arm 56. Such arm 56 bears, in its intermediate point, a constraining pin
61 with the strut 53 and at its upper ends a constraining pin 63 with the clamp carrier
bar 31.
[0024] Depending on the rotation m imparted to the threaded bar 58, for each lifting arm
56 placed on the faces of the spinning frame, the movable support 51 moves closer
to or away from the fixed support 50 to which it is bound with the strut 53 and, respectively,
it lifts or lowers the lifting arm 56 and with this lifts or lowers vertically the
clamp carrier bar 31 to the desired work levels. Salient feature and advantage of
such pantograph 49 supporting the clamp carrier bar 31 is that it does not require
back and forth rotary movements with respect to the face of the spinning frame for
taking and placing the moved bobbins and tubes.
[0025] The doffing of the bobbins is carried out as follows, as an example. The ring spinning
process is governed by a governing and control unit which detects the achievement
of the desired yarn quantity in meters, produced in bobbins on every spinning unit,
and it commands the start of the doffing process of the completed bobbins 15 and their
substitution with new tubes 16, on which new bobbins will have to be wound, operating
in parallel over all the spinning units which compose the ring spinning frame.
[0026] The spinning frame first provides for binding the yarns 10 on the lower ring nuts
of the bobbin carrier spindles 20, stopping the rotation of the spindles, lowering
the ring-rail 14 and the balloon containment ring 18 in all the spinning units as
well as raising the thread guide 11 so as to not interfere with the doffing members.
[0027] The doffing sequence is exemplifyingly carried out with the following steps:
- ascending of the pantograph 49,
- rotation of the clamp carrier arms 34 in the position of the spindles 20,
- descending of the pantograph 49 so to fit the clamps 32 on the finished bobbins 15
and close them,
- lifting the pantograph 49 to the maximum level, tearing of the yarn tails and extraction
of the bobbins 15 from the bobbin carrier spindles 20,
- rotation of the arms 34 in the retracted position of the pins 29,
- descending of the pantograph 49 so to fit the bobbins 15 on the parking pins 29,
- opening of the clamps 32 with release of the bobbins 15 on the pins 29,
- partial re-ascending of the pantograph 49 with simultaneous rotation of the arms 34
in the intermediate travel position of the conveyor belt 27,
- descending of the pantograph 49 until it inserts the clamps 32 on the tip of the tubes
16 on the pegs 28 on the conveyor belt 27 and to close the clamps 32,
- re-ascending of the pantograph 49 to the maximum level, bringing the tubes 16 therewith,
- rotation of the clamp carrier arms 34 in the extended position of the spindles 20,
- descending of the pantograph 49 so to fit the tubes 16 on the spindles 20, clamp opening
and release of the tubes,
- re-ascending of the pantograph 49 to the maximum level and rotation of the arms 34
in the retracted position of the pins 29.
[0028] The process according to the invention provides for freeing the spindles 20 of the
finished bobbins and to fit the new tubes thereon, before starting the transportation
of the bobbins towards the winding. The completed bobbins are positioned on the parking
station of the pins 29.
[0029] At this point, the spinning frame can start the so-called "spindleful", i.e. restart
the production of new bobbins on the new changed tubes. The doffing continues as follows:
- descending of the pantograph 49 to the minimum level, closure of the clamps 32 on
the tips of the bobbins 15 parked on the pins 29,
- partial re-ascending of the pantograph 49,
- rotation of the arms 34 in the intermediate travel position of the conveyor belt 27,
- descending of the pantograph 49 so to fit the finished bobbins 15 on the pins of the
pegs 28 on the conveyor belt 27, opening of the clamps 32 and release of the bobbins,
- partial re-ascending of the pantograph 49 and rotation of the arms 34 in the retracted
position of the pins 29.
[0030] At this point, with the spinning already underway, the finished bobbins 15 are progressively
brought by the conveyor belt 27 to the subsequent winding.
[0031] With respect to the technical solutions of the prior art, currently in use, which
first deposit the bobbins on the conveyor belt and then bring the tubes to the spinning
units, the doffing results shorter and with less dead times in spinning. With regard
to the doffing device, the execution of the approaching and moving away movement to/from
the spinning units with only the clamps 32, rather than with the entire pantograph,
leads to considerable improvements. The bulk of the device does not increase during
the doffing. It is not necessary to have the conveyor belt make half pitches for bobbins
and tubes during the doffing, with greater driving precision. The rotation mechanism
for the approaching and moving away only affects the clamp carrier arms and not the
entire pantograph: the movements result more precise. The space underneath the spindle
carrier rail results free and is thus available both for reducing the height of the
spinning frame, and for working with tubes of increasing length, or finally for inserting
other devices without increasing the height of the spinning frame. The travel path
of the conveyor belts for tubes and bobbins is not affected by the bulk of the machine
section, and can be placed at the sides of the control heads without modifying their
shape.
1. Doffing device (30) for moving, in a ring spinning frame, tubes (16) and bobbins (15)
between the bobbin carrier spindles (20) of the spinning units which compose the spinning
frame and a service transport device (27) on the two faces of the spinning frame,
on which the empty tube or the finished bobbin to be transported are brought from
time to time, comprising a clamp carrier bar (31) which bears clamps (32) for the
engagement of the bobbins (15) and the tubes (16) to be moved and a pantograph device
(49) for lifting and lowering the clamp carrier bar (31), characterised in that the clamps (32) are borne with a series of arms (34) placed on the clamp carrier
bar (31) and moved closer to or away from the face of the machine in the work positions,
and that the support pantograph (49) of the clamp carrier bar (31) is only driven
downward or upward, without requiring rotary movements in moving closer to and away
from the face of the spinning frame.
2. Doffing device according to claim 1, characterised in that the arms (34) are placed and pivoted on the clamp carrier bar (31) so to rotate with
rotation (r) in the various angles of the work positions.
3. Doffing device according to claim 1, characterised in that the clamp carrier arms are moved by translation, maintaining such arms in fixed position,
orthogonal with respect to the clamp carrier bar (31) and providing them with a slider
part which bears the clamp (32) and which is extendible in order to be orthogonally
lengthened and retracted with respect to the spinning units.
4. Doffing device according to claim 1, characterised in that near and parallel to the service transport device (27) on the two faces of the spinning
frame, a parking station is provided for which is constituted by a series of vertical
pins (29), one for each ring spinning unit, integral with the fixed structure of the
machine.
5. Doffing device according to claim 2, characterised in that the rotation (r) of the arms (34) is made with a bar (40) for connecting all the
arms (34) with pins (41), which constrain all the arms to coherently rotate with each
other in accordance with the axial translation of the bar (40), so to form a pantograph
for the approaching/moving away movement of the clamps (32) with respect to the movement
positions in the horizontal plane.
6. Doffing device according to claim 5, characterised in that at the end of the connection bar (40), a plate (42) is mounted which is connected
with a pin (43) to the bar (40) and in turn pivoted on the clamp carrier bar (31)
with a pin (44) for driving the pantograph for moving the clamps (32) closer / further
away.
7. Doffing device according to claim 6, characterised in that the driving in rotation around the pin (44) of the plate (42) is made by making a
toothing (46) in the edge of the plate (42), which engages a coherent toothing of
a gearmotor (47) which is made to rotate in clockwise/anticlockwise sense in order
to impart alternating rotations in accordance with the arrows (r) to the plate (42).
8. Doffing device according to claim 5, characterised in that the connection bar (40) is driven into axial translation with a screw/nut screw system
driven in rotation with a stepping motor in controlled rotation in the two directions.
9. Doffing process for moving, in a ring spinning frame, empty tubes (16) and finished
bobbins (15) between the bobbin carrier spindles (20) of the spinning units which
compose the spinning frame, a parking station constituted by pins (29) and a service
transport device (27) on the two faces of the spinning frame, on which the empty tube
or the finished bobbin to be transported are individual brought from time to time,
by means of a doffing device (30) comprising a clamp carrier bar (31) which bears
clamps (32) for engaging the bobbins (15) and the tubes (16) to be moved and a pantograph
device (49) for the lifting and lowering of the clamp carrier bar (31), characterised in that first the bobbin carrier spindles (20) are freed of the finished bobbins (15), positioning
them on the parking station of the pins (29), that then the new tubes (16) are drawn
on the transport device (27) and then fit on the freed bobbin carrier spindles (20),
once again starting the spinning, and that finally the finished bobbins (15) positioned
on the parking station of the pins (29) are drawn and delivered to the transport device
(27) for their transport to the winding.
10. Doffing process according to claim 9, characterised in that bobbins (15) and tubes (16) are moved with clamps (32) which engage the upper part
of the tube (16).
11. Doffing process according to claim 9, characterised in that the support pantograph (49) of the clamp carrier bar (31) is only driven downward
or upward, without rotary movements approaching or moving away from the face of the
spinning frame.
12. Doffing process according to claim 11, characterised in that the clamps (32) are borne in their work positions, approaching or moving away from
the face of the machine, with series of movable arms (34) placed on the clamp carrier
bar (31).