[0001] The present invention refers to an improved warper and to a method of warping.
[0002] It is known that warpers used for carrying out a so-called "thread-by-thread" warping
have a drum or "barrel"-like structure over which the warp threads are wound according
to a sequence corresponding to the selected warping program. The threads, which are
fed by a plurality of reels disposed on a creel in a precise order, are wound over
said structure by means of a thread-guide rod rotating in a vertical plane. To this
end, the free end of each of said rods is suitably shaped to engage the threads as
they are gradually handed over by a presentation system and laid down onto a series
of ring-like closed belts. Such belts develop onto the drum orthogonally to the plane
of rotation of the thread-guide rod. They allow the turns of thread to move away progressively
from the deposition site by displacing the same turns along the longitudinal development
of the drum. Once a predetermined number of turns of thread in the course of formation
is reached, the same thread is released and drawn back up to the point of initial
presentation. Upon completion of the warp, the latter is downloaded from the warper,
that is, transferred onto a beam intended for a loom or other textile machine or apparatus.
[0003] Documents EP 832.998, EP 882.820 and EP 1.036.867 disclose in greater details the
operation and structure of the warpers of this type.
[0004] One of the more significant drawbacks lies on the fact that, especially in case of
a large number of threads and high warping speed, the tension of the threads wound
over the belts results exceedingly high. As a consequence, the pressure that the same
threads exert upon the belts and the base structure is so elevated as to prevent the
belts from moving fast. Accordingly, the speed of the latter cannot be increased beyond
a certain limit. Moreover, especially when some threads of the warp thus formed result
improperly crossed to other threads of the same warp, it results extremely difficult,
if not impossible, to perform the whole transfer of the warp onto the beam when the
pressure exerted by the threads is exceedingly high.
[0005] Further drawbacks stem from changes in tension of the warp which occur when the thread
being worked is made to change in typology, count and nature of the material from
which it is made. All of this may also take place with the so-called "multi-thread
warping" which provides for winding more threads at the same time and the use of a
rotating creel on which the reels of thread are located.
[0006] The main object of the present invention is to overcome the said drawbacks.
This result has been achieved, according to the invention, by providing an apparatus
and implementing a method having the characteristics described in the independent
claims. Further characteristics being set forth in the dependent claims.
[0007] The present invention makes it possible to adjust the tension of the warp threads,
that is, the pressure exerted by them upon the belts and structure of the warper.
It is thus possible to drive the belts more rapidly in both the directions of the
respective longitudinal axes, that is, both in the direction of formation or "growth"
of the warp and in the opposite direction. In addition to this, there is the fact
that the warp can be discharged and transferred onto the beam far more easily. Besides,
the system according to the invention is relatively simple to make, cost-effective
and reliable even after a prolonged service life and can be implemented both in case
of thread-by-thread and multi-thread warping.
[0008] These and other advantages and characteristics of the invention will be best understood
by anyone skilled in the art from a reading of the following description in conjunction
with the attached drawings given as a practical exemplification of the invention,
but not to be considered in a limitative sense, wherein:
- Fig. 1 shows diagrammatically a front view of a warper according to the present invention;
- Fig. 2 shows diagrammatically a perspective view of the warper of Fig. 1;
- Fig. 3 is a scheme of a feasible embodiment of the means intended to release and adjust
the tension of the threads being worked;
- Fig. 4 shows diagrammatically a further system for operating the means for adjusting
the threads' tension;
- Fig. 5 shows diagrammatically a further embodiment of the invention;
- Fig. 6 shows an enlarged detail of the drawing of Fig. 5;
- Fig. 7 shows a diagram relating to the operation of the present warper;
- Fig. 8 is a partial schematic diagram relating to the configuration taken by a thread
being deposited onto the warper.
[0009] Reduced to its basic structure, and reference being made to the figures and the attached
drawings, a warper according to the invention comprises:
- a fixed structure (1) of substantially cylindrical shape with horizontal axis (o-o);
- a plurality of ring-like closed belts (2), each of which is disposed parallel to said
axis (o-o), in correspondence of the outer surface of said structure (1);
- a support (3) having U-shaped cross-section and being fixed to the structure (1) for
each of said belts (2): each belt (2) being wound over two corresponding pulleys (20)
located at the ends of the relevant support (3);
- more lease bars (4) disposed parallel to said belts (2) in correspondence of parts
of the structure (1) not engaged by the belts (2);
- at least one electric motor (not shown in the drawings) for moving at least one of
the pulleys (20) of each of said belts (2);
- at least one thread-guide rod (5) rotating about said axis (o-o): the said rod (5)
making it possible to remove the threads (F) and lay them down onto said belts (2)
according to a sequence corresponding to the selected warping program;
- means (6) for disposing each thread (F) in a position for its removal, or presentation
to the rod (5), and for the recovery of the same thread when giving the command for
its moving away from the rod (5);
- a feeding unit comprising at least a creel (not shown in the drawings) on which the
reels of thread (F) are disposed.
[0010] The constructional and operative elements above described are known per se to those
skilled in the art and will not therefore be described in greater detail. The above
cited documents disclose in greater detail the warpers thus constructed.
[0011] In practice, the threads (F) are presented by the means (6) to the rod (5) in the
order preset by the program. The rod (5), once it has hooked a thread (F) presented
by the means (6), draws it into rotation about the axis (o-o) to allow it to be laid
down onto the active surface (21) of the belts, that is, the surface facing outwardly.
The belts (2), as the rod (5) rotates with the thread hooked by the same rod, move
in the direction of arrow (A) in Fig. 2, owing to the rotation imposed to the respective
pulleys (20). As a consequence, as many adjacent turns of thread are formed as those
provided by the warping program. Once the programmed number of turns has been reached,
the thread is moved away from the rod (5) and recovered by the means (6), and the
same operation is then repeated for the other threads until the warp is completed.
[0012] A warper according to the present invention is advantageously provided with one or
more tension means or tighteners (7) whose operational arrangement can be varied and
on which the threads (F) can be deposited by the rod (5), the same threads being able
to move afterwards from said tighteners onto the belts (2). According to the example
shown in the figures of the accompanying drawings, the said tighteners (7) are engaged
with the structure (1) in correspondence of the space between any two belts (2) on
the side of rod (5).
Each tightener (7) is associated with a corresponding actuator (71) allowing its operational
arrangement to be changed according to the program.
[0013] The said tighteners (7) are intended - as best described later on with reference
to the diagram of Fig. 8 - to dispose the threads (F) being carried by the rod (5),
partly onto a circumference (C1) (delimited by an array of suitable surfaces (70)
exhibited by the same tighteners on the side facing outwardly) having a diameter larger
than the circumference (C2) delimited by the active surface (21) of belts (2) in any
plane orthogonal to the axis (o-o) of structure (1), and partly onto said circumference
(C2). In other words, by activating the tighteners (7) so that the respective surfaces
(70) will delimit a circumferential or cylindrical surface of a radius larger than
that of (C2), delimited by the active surface (21) of belts (2), each thread (F) drawn
by the rod (5) into rotation about the axis (o-o) will result partly onto the surface
(70) of tighteners (7) and partly onto the belts (2). Upon the subsequent spontaneous
transfer of the threads from the surface (70) of tighteners (7) to the surface (21)
of the belts (2), the decreasing diameter or length of the turns of thread implies
a corresponding reduction of their tension and, accordingly, the pressure exerted
onto the belts (2) and structure (1) decreases as well. The threads (F) move spontaneously
onto the belts (2) owing to the chute-like shape of surfaces (70) exhibited by the
tighteners (7).
[0014] The operative arrangement of the tighteners (7) can be varied in order to correspondingly
varying the diameter of the circumferential or cylindrical surface delimited by said
surfaces (70) in response to electrical signals from at least one pressure sensor
(8). The latter is intended for detecting the pressure exerted each time by the threads
on the same tighteners. To this end, and as illustrated in the figures of the accompanying
drawings, each sensor (8) is able to be mounted on a corresponding tightener (7) upstream
of the relevant belt (2), and may exhibit an external surface making up a joining
track between the said surface (70) of tighteners (7) and the belts (2). For example,
each sensor (8) can be made up of a load cell of a type normally available on the
market. The signals emitted from each sensor (8) are transmitted to a programmable
electronic unit (UE) - consisting for example of a PC - with which the actuators (71)
are associated.
In case more pressure sensors (8) are used, data detected by them may be averaged
to find a mean value which the unit (UE) will assume to be the pressure exerted in
the whole by the warp on the tighteners. Should this value be greater than a programmed
limit, the actutators (71) would be activated so as to dispose the surfaces (70) of
tighteners (7) over a cylindrical surface of larger radius, until the pressure value
detected by sensors (8) will coincide with the programmed one, as required.
[0015] Alternatively, the tighteners (7) may be activated according to a program providing
for changing the operative arrangement thereof as the warp increases, in order to
thereby increase progressively, either with continuity or step-by-step, the diameter
of said surface also in the absence of sensors (8).
In the diagram of Fig. 7, the plane P1 orthogonal to the rotation axis (o-o) of rod
(5) contains the surface (C1) which corresponds to the cross-section of the surface
delimited by the tighteners' surfaces (70). The plane (P1) is the one in which the
rod puts down the threads (F). The surfaces (70) of tighteners (7) result astride
of such plane, that is, each one of the tighteners is disposed partly upstream and
partly downstream of said plane (P1). In the same diagram, the plane P2, also orthogonal
to said axis (o-o), is the one which contains the circumference (C2) whose radius
is constant along the axis (o-o).
[0016] According to the exemplifying embodiment illustrated in Fig. 3, each tightener (7)
is made up of a lever longitudinally located between two adjacent belts (2). Such
lever is engaged with the structure (1) via a horizontal hinge (72) in correspondence
of the end which is the furthest from the plane (P1) of action of rod (5). This connection
allows the lever (7) to be rotated upwards (U) and, respectively, downwards (D) under
control of an actuator (71) which, in the example, is an electric motor fixed to the
structure (1). Fitted on the shaft of motor (71) is a worm screw (73). Meshing with
this screw is a pinion (74) associated with a rack (75) which is engaged with the
lever (7) at a point (V) upstream of the hinge (72). Starting the motor (71) causes
the rotation of the worm screw (73) and of pinion-rack group (74, 75). This causes
the rotation of the lever (7) about the axis of hinge (72), either upwards or downwards,
depending on how the motor (71) is operated. The latter is electrically connected
to a D/A converter (9) able to generate electrical pulses in response to corresponding
control signals from the programmable unit (UE). The latter, in turn, receives and
processes, according to the program, the signals coming from the sensor (8). The said
rotation of lever (7) brings about a corresponding lowering or lifting of its surface
(70) relative to the operating plane (21) of belts (2), that is, a decrement, respectively,
an increment of diameter of said circumference (C1). In case the pressure sensor is
lacking, the programmable unit (UE) operates the actuator (71) so as to rotate the
tightener (7) upwards (U) as the warp increases, that is, as the useful number of
revolutions of rod (5) becomes larger. This number is a data transmitted in a conventional
manner to the unit (UE) via an encoder associated with the shaft (50) of rod (5).
[0017] According to a further example of embodiment shown in Fig. 4, each tightener is made
up of a lever having its fulcrum, within a median portion thereof, on the structure
(1) of the warper, and at the height of the front pulley (20) of the corresponding
belt (2). The rear end of the lever is connected to the stem of a hydraulic actuator
(71') which drives it into rotation about the fulcrum (72'). Said actuator (71') is
fed by a pump (710) through a valve (711) which receives the hydraulic fluid from
the pump (710) and delivers it to the actuator (71'). The said valve (711) is associated
with the unit (UE) via an interface of traditional type (712). The same interface
(712) is intended for connecting the unit (UE) to the feed circuit (713) of an electric
motor (714) which operates the pump (710). The actuator (71') is solid to the warper's
structure (1). The example shown in Figs. 5 and 6 provides, likewise that of Fig.
4, for the use of more hydraulic actuators which are associated with the unit (UE)
and a hydraulic pump (710) and are attached to the structure (1). In this example,
each actuator is intended for moving a body (7') connected to the respective stem
and supported by a guide fork (700) solid to said structure (1). The said body (7')
makes up the tightener in this example of embodiment of the invention. The fact of
depositing the threads (F) onto a surface having a diameter larger than that of surface
(C2) defined by the whole of belts (2) implies a corresponding reduction of the pressure
exerted by the warp onto the same belts and structure (1), as well as an easier transfer
of the warp onto the beam.
[0018] When the warp is in the course of formation, that is, during the deposition of threads
by the rod (5), if the sensed pressure is equal to the said limit value, the tighteners
(7; 7') do not interfere directly with the threads (F) during the step of warp formation,
since they are at the same level as the belts (2). When the said limit value is exceeded,
the tighteners (7; 7') are rotated as indicated by arrow (U) in Figs. 3 and 4, so
as to increase the diameter of the surface on which the threads (F) are laid down.
Upon the spontaneous transfer or sliding of threads (F) from the surface (70) of tighteners
(7; 7') to the surface (21) of belts (2) there is obtained a corresponding reduction
of the thread tension. When the said pressure is less than the preset limit value,
the tighteners (7; 7') are rotated downwards, as indicated by arrow (D) in Figs. 3
and 4.
The driving of tighteners (7; 7') into motion is consistent with the difference between
the pressure value detected by the sensor (8) and the programmed limit.
[0019] The initial position of tighteners (7; 7') can be chosen, for example, so that, upon
starting the machine, the threads will result already disposed on a cylindrical surface
(the one delimited by surfaces 70 of the same tighteners) having a radius larger than
said circumference (C2) in order to have the possibility of reducing the pressure
thereof from the first moment of this step. In the latter case, the actuators (71;
71') will be activated for rotating the tighteners (7; 7') downwards, so that the
surface delimited by the active surfaces (70) of tighteners (7; 7') will have a radius
smaller than that of circumference (C2).
In case of no sensors (8), the movement of tighteners (7; 7') is driven directly by
the unit (UE) being so programmed as to dispose them in a position increasingly elevated
as the warp is formed or "grows", that is, as the number of revolutions of the rod(s)
(5) about the axis (o-o) becomes larger.
[0020] An operating method according to the invention includes therefore the following steps:
- detecting or predetermining the pressure exerted by the warp in at least one point
(8) upstream of said belts (2); and
- decreasing, respectively increasing the tension of the threads (F) as they are being
laid down onto the warper's belts, should the said pressure be higher, respectively
smaller than a preset limit value.
[0021] The presetting said pressure value can be made on the basis of statistics or experience
or requirements from the producer or user. The thus determined pressure values will
correspond to the operative positions of the tighteners, which positions are stored
in a conventional way by the user or manufacturer into the memory of the central unit
(UE).
[0022] According to the present operating method, the tension of the threads (F) can be
adjusted, as above indicated, by depositing them, at least partially, onto a substantially
cylindrical surface having a diameter other than that of the surface defined by the
operating planes (21) of belts (2), should the said pressure be higher or lower than
a preset limit value.
It will be appreciated that the said sensed or predetermined pressure values can be
made to vary in relation to the typology of the yarn (count, material or other) employed
each time for the formation of the warp, that is, in relation to any difference between
yarns of diverse typology as regard to their behaviour during the formation process.
1. Warper comprising a fixed structure (1) on which more belts (2) are disposed for moving
the warp in the course of formation, means for feeding warp-forming threads (F), means
(6) for presenting the threads (F) to at least one rod (5) allowing the same threads
(F) to be transferred over said belts (2) and be recovered therefrom, characterized in that it comprises one or more tighteners (7; 7') each of which is provided with a surface
(70) able to temporarily receive the threads (f) carried by said rod (5) and from
which surface (70) the threads (F) move onto said belts (2), and in that the position of said surface (70) of tighteners (7) relative to the operating plane
(21) of the belts (2) can be varied in relation to the pressure exerted by the threads
at a location (8) upstream of the belts (2) .
2. Warper according to claim 1, characterized in that each of said tighteners (7; 7') is disposed between two adjacent belts (2).
3. Warper according to claim 1, characterized in that said tighteners (7; 7') are associated with corresponding actuators (71; 71').
4. Warper according to claim 1, characterized in that it comprises at least one sensor (8) able to detect the pressure exerted by the threads
(F) at a location upstream of belts (2).
5. Warper according to one or more preceding claims, characterized in that it comprises a programmable unit (UE) able to receive data relevant to said pressure
in order to calculate a pressure value to be compared with a preset limit and to drive
the tighteners (7) into motion, should the difference between values corresponding
to data received therefrom and the preset limit value be other than zero.
6. Warper according to one or more preceding claims, characterized in that it comprises a programmable unit (UE) able to receive data relevant to said pressure
in order to calculate a pressure value to be compared with a preset limit and to drive
the tighteners (7) into motion according to a program as the warp is formed on the
warper.
7. Warper according to one or more preceding claims, characterized in that each of said tighteners (7) consists of a lever longitudinally disposed between two
adjacent belts (2) and engaged with the structure (1) by a hinge (72) having horizontal
axis.
8. Warping method comprising the steps of feeding, removing and recovering the threads
(F) by which the warp is formed, by using a warper with fixed structure (1) on which
more belts (2) are disposed for transporting the warp and to receive the threads (F)
as they are laid down, characterized in that it includes reducing or increasing automatically the tension of the threads being
laid down, should the pressure exerted by same threads at a location upstream of the
belts be higher or lower than a preset limit value.
9. Method according to claim 8, characterized in that the said tension is adjusted by depositing the threads at least partially onto a
cylindrical surface having a diameter greater that that of the surface defined by
the operating planes (21) of said belts (2), the diameter of said surface of threads
deposition varying as the warp is formed.
10. Method according to either or both claims 8 and 9, characterized in that the said warping is of thread-by-thread or multi-thread type.