[0001] The invention relates to a method for inserting a weft thread into a shed of an airjet
weaving machine, wherein the weft thread is transported by compressed air coming from
a main nozzle device and at least one set of relay nozzles. Preferably, the compressed
air which is supplied to the main nozzle device and to the at least one set of relay
nozzles is controlled by shut-off valves which are controlled by a control unit. The
invention also relates to an airjet weaving machine for applying such a method, in
other words an airjet weaving machine which can apply a method as mentioned above.
[0002] It is known from
WO 2007/057217 A1 to supply compressed air successively to the successive sets of relay nozzles while
the weft thread is transported through the shed. The different sets of relay nozzles
are provided with compressed air via shut-off valves. Each shut-off valve is connected
to a set of relay nozzles and each shut-off valve is controlled by a control unit.
Measurements are carried out on the weft thread while the weft thread is transported
through the shed. For each set of relay nozzles a moment can be determined when the
supply of compressed air to this set of relay nozzles is interrupted. This moment
can be determined in function of said measurements. This allows that both a slow weft
thread and a fast weft thread are sufficiently supported by compressed air coming
from successive sets of relay nozzles. As described in
WO 2007/057217 A1, an influence on the supply of compressed air to a set of relay nozzles can be chosen
strong, medium or limited.
[0003] Airjet weaving machines are known from
WO 2007/057217 A1, wherein weft threads coming from different weft thread buffers are inserted into
the shed according to a pattern. For each weft thread coming from a weft thread buffer
a corresponding main nozzle device with main nozzles arranged in series is provided.
Further a number of sets of relay nozzles is provided for transporting the weft threads,
coming from the different weft thread buffers, through the shed, more in particular
for transporting the weft threads along a guide channel through the shed. For inserting
a weft thread into the shed, compressed air can be supplied to each main nozzle of
a main nozzle device via associated shut-off valves that are arranged between a reservoir
with compressed air and a corresponding main nozzle. Compressed air is supplied to
each set of relay nozzles via associated shut-off valves that are arranged between
a reservoir with compressed air and the associated set of relay nozzles. Each set
of relay nozzles comprises at least one relay nozzle and for example two or three
relay nozzles that are mounted next to one another.
[0004] The amount of compressed air which is supplied during a time interval to a main nozzle
and/or to a set of relay nozzles can be regulated during weaving by means of a motor-controlled
throttle valve that is mounted between the reservoir and a corresponding main nozzle
and/or set of relay nozzles. Such a motor-controlled throttle valve comprises for
example a controllable stepping motor that can be controlled in both directions with
a number of steps by means of a control unit. The control of the amount of supplied
compressed air during a time interval can be regulated during weaving in function
of a deviation of a measured insertion parameter. It is possible for example to control
the amount of compressed air which is supplied during a time interval so, that an
inserted weft thread reaches the end of the shed approximately at a desired angular
position of the weaving machine. According to a possibility, an average deviation
is determined between the moment at which the weft thread reaches the end of the shed
and the moment at which the main drive shaft of the weaving machine reaches a given
angular position. The throttle valves can then be controlled in such a way that the
average deviation that is determined during several insertions of weft threads coming
from the corresponding weft thread buffers will be approximately equal to a given
value.
[0005] DE 42 26 693 A1 shows a method, wherein upon starting a normal weaving operation, a supply of compressed
air is adjusted. According to one method shown in this document, first a supply pressure
to the main nozzles is increased until a weft thread is sufficiently fast, i.e. until
a measured arrival time is shorter than a desired arrival time. In case the measured
arrival time is longer, i.e. in case the weft thread is too slow, the pressure is
increased. Then, a supply pressure to the relay nozzles is reduced until a weft thread
becomes too slow, i.e. until a measured arrival time is longer than a desired arrival
time. In case the measured arrival time is longer, i.e. in case the weft thread is
too slow, the pressure is increased. Next, a duration of the supply of compressed
air to the main nozzles is reduced until a weft thread becomes too slow. When the
weft thread becomes too slow, the duration is adjusted to the previous value of the
supply of compressed air to the main nozzles. Finally, a duration of the supply of
compressed air to the relay nozzles is reduced until a weft thread becomes too slow.
When the weft thread becomes too slow, the duration is adjusted to the previous value
of the supply of compressed air to the relay nozzles.
[0006] It is an object of the invention to provide a method and an airjet weaving machine
for reducing the amount of compressed air which is used for the insertion of weft
threads into a shed, while weaving errors are avoided during reducing the amount of
compressed air which is used for inserting weft threads into a shed.
[0007] This object is solved by a method according to claim 1 and an airjet weaving machine
according to claim 10.
[0008] A method for inserting a weft thread into a shed of an airjet weaving machine comprising
a main nozzle device and at least one set of relay nozzles is provided, wherein a
standard setting for the supply of compressed air to the main nozzle device and to
the at least one set of relay nozzles is determined, the standard setting for the
supply of compressed air to the main nozzle device and to the at least one set of
relay nozzles is adjusted in order to reduce the supply of compressed air, a stability
of insertions of a weft thread with the adjusted standard setting is observed, the
standard setting for the supply of compressed air to the main nozzle device and to
the at least one set of relay nozzles is adjusted such that the supply of compressed
air to the at least one set of relay nozzles is decreased until a weft insertion becomes
unstable, and if a weft thread insertion becomes unstable when an adjusted standard
setting for the supply of compressed air to the main nozzle device and to the at least
one set of relay nozzles is applied, the supply of compressed air to the main nozzle
device is decreased in order to avoid the instability.
[0009] If the supply of compressed air to the main nozzle device is decreased, the inserted
weft thread is less pushed into the shed. Correspondingly, the speed of the weft thread
at the entrance of the shed will also fall, so that a leading end of the weft thread
will not be slower than the trailing end of the inserted weft thread. This allows
a setting for the supply of compressed air wherein the supply of compressed air to
the sets of relay nozzles is interrupted at an earlier moment, without the risk that
the inserted weft thread will form loops due to differences in speed, in particular
due to a higher speed at the entrance of the shed than at the end of the shed. As
a result, after decreasing the supply of compressed air to the main nozzle device,
the setting can be further adjusted by decreasing the supply of compressed air to
the at least one set of relay nozzles.
[0010] Preferably, after the supply of compressed air to the main nozzle device has been
decreased, the standard setting is again further adjusted by decreasing the supply
of compressed air to the at least one set of relay nozzles until insertions of a weft
thread become again unstable.
[0011] A standard setting can be defined as a function of a weaving pattern, a yarn type
and other parameters, under which previously determined data, such as measurements
on transported weft threads during their transport. By observing the stability of
the insertion of the weft thread it is possible to optimize the standard setting,
while weaving errors are prevented. If the observed weft thread insertion is stable,
the standard setting can be further adjusted, for example a supply of compressed air
can be further decreased.
[0012] Preferably, the interruption of the compressed air supply to the at least one set
of relay nozzles is further delayed or advanced with respect to a standard setting
in function of measurements on a transported weft thread during transport of this
weft thread as described in
WO 2007/057217. If the weft thread insertion is stable, the standard settings can be adjusted, in
particular, a period during which compressed air is supplied to a corresponding nozzle,
can be shortened, in other words the interruption of the supply of compressed air
for the standard setting can be advanced in relation to the weaving cycle. The adjustment
can be repeated until the weft thread insertion becomes unstable. When the weft thread
insertion becomes unstable, the standard settings can be adjusted by extending the
period of air supply, in particular by delaying an interruption of air supply to the
sets of relay nozzles, and/or adjusting an air supply to the main nozzle device. Thereby,
a limit for decreasing the air supply to the sets of relay nozzles is determined.
According to a preferred embodiment, a user or operator can choose to what extent
the standard setting for the at least one set of relay nozzles may be influenced.
For example, the user or operator can choose between low influence, medium influence
or high influence.
[0013] According to an embodiment, an interruption of a compressed air supply to the main
nozzle device and/or to the at least one set of relay nozzles is adjusted in function
of measurements on a transported weft thread in order to adjust the standard setting.
The moments for interrupting and/or commencing the compressed air supply to the main
nozzle device and/or to the sets of relay nozzles can be alternately adjusted. According
to another embodiment first only the setting for the air supply to the sets of relay
nozzles is adjusted, and if a limit for decreasing the air supply to the sets of relay
nozzles is reached, the moment for interrupting the supply of compressed air to the
main nozzle device is also set earlier. The air supply to the main nozzle device is
preferably only reduced to an amount which allows that the weft thread is still accelerated
with sufficient force during the start of the insertion, so that this reaches a desired
speed, which is determined by the force, i.e. the pressure and/or the air flow per
time unit, exerted by the main nozzle device. Thereby it is accomplished that the
relay nozzles support the weft thread with a minimum force and that an unnecessary
acceleration of the weft thread by the main nozzle device at the entrance of the shed
is avoided.
[0014] According to another embodiment, the main nozzle device is provided with a first
main nozzle and a second main nozzle, wherein the supply of compressed air to the
first main nozzle is decreased, when a weft thread insertion becomes unstable. The
first main nozzle is also called auxiliary main nozzle or fixed main nozzle, in case
the first main nozzle is fixedly mounted on the frame of the weaving machine. Preferably,
viewed in the moving direction of the weft thread the first main nozzle is arranged
so, that this precedes the second main nozzle which is mounted near the shed, in particular
mounted next to the reed on the sley. The second main nozzle is also called moveable
main nozzle, in case the second main nozzle is mounted on the sley. In this way, the
second main nozzle, which is arranged next to the reed, can further insert the weft
thread into the shed, in other words this can blow as long as necessary to insert
the weft thread into the shed. Preferably, the setting for the supply of compressed
air to the moveable or second main nozzle is not changed or is changed only limited
by adjusting the setting. In order to avoid loops at the entrance of the shed, the
pressure of the supplied compressed air to the moveable main nozzle is preferably
higher than the pressure of the supplied compressed air to the fixed main nozzle.
In an embodiment, the first, in particular the fixed main nozzle can be set to only
assist to pull the weft thread from a prewinder, while the second, in particular the
moveable main nozzle blows the weft thread into the shed.
[0015] Preferably, a number of successive sets of relay nozzles is provided, wherein the
standard setting for a compressed air supply to the number of sets of relay nozzles
is adjusted making use of a belly pattern or bell-shaped curve. According to the invention,
a belly, belly pattern or bell-shaped curve is defined as a pattern, according to
which in a row of successive sets of relay nozzles, sets of relay nozzles mounted
near a centre of the shed are influenced stronger than sets of relay nozzles mounted
on the sides of a shed. For example, if nine sets of relay nozzles are provided, then
the 4
th, 5
th and 6
th set are the most strongly influenced, while the 1
st, 2
nd, 8
th and 9
th set are not or almost not influenced and the 3
rd and 7
th set are slightly influenced. In another example, a belly pattern is chosen such that
it is symmetrical with respect to a central set of relay nozzles. For example, at
the middle sets of relay nozzles a setting of an interruption moment can be adjusted
in a first step to occur 5% earlier with respect to a previous standard interruption
moment for the middle sets of relay nozzles, e.g. the 5
th set of relay nozzles when nine sets are provided. For the 1
st, 2
nd, 8
th and 9
th set of relay nozzles the moment of interruption of an air supply can first be kept
constant, for the 3
rd and 7
th set of relay nozzles can be chosen to occur 1% earlier, and the interruption moment
for the 4
th and 6
th set can be chosen to occur 3% earlier. If the weft thread insertion remains stable
after the adjustment, the interruption moment can be further adjusted until the weft
thread insertion becomes unstable or until limit values for adjusting an interruption
moment are reached. Limit values can be set dependent on a chosen influence setting.
When for example, a low influence setting is chosen, a limit value can be set on 30%
at the deepest belly point, i.e. the middle sets of relay nozzles. When an average
or a high influence setting is chosen, a limit value can be set on 40% or 50% at the
deepest belly point, respectively. In addition, the settings for each inserted weft
thread can be adjusted according to the measurements on the determined inserted weft
thread. For example, when a slow weft thread is detected, a later actual moment of
interruption is used than in cases when a fast weft thread is detected. Slow and fast
weft threads can be distinguished for example depending on a time difference between
a moment or a point of time that an unwinding of a weft thread winding is accomplished,
for example the second weft winding and a previously chosen moment in the weaving
cycle. When a slow weft thread is detected, a moment for the interruption of an air
supply can be chosen that lies between the adjusted standard moment set in accordance
with the adjusted standard setting according to the invention and an original standard
moment set by an operator, in other words a standard moment of an initial setting.
[0016] A stable insertion of a weft thread is hereby determined as an insertion wherein
no instability takes place, more particularly wherein no weaving error occurs. According
to an embodiment, an unstable weft thread insertion is identified by detecting at
least one weaving error. For example, according to the invention a weaving error,
also called a weaving irregularity, is defined as a situation wherein a leading end
of a weft thread is not supported sufficiently for allowing the weft thread to be
transported in a stretched condition through the shed.
[0017] For example, a weaving error is detected when the time difference between a measured
moment wherein an inserted weft thread arrives at a first measurement point and a
measured moment wherein the inserted weft thread arrives at a second measurement point
exceeds a predetermined threshold. A weaving error can also be detected when the average
time difference between a measured moment wherein an inserted weft thread arrives
at a first measurement point and a measured moment wherein the inserted weft thread
arrives at a second measurement point exceeds a predetermined threshold.
[0018] For example, a weaving error is detected when the time difference between an expected
arrival moment of an inserted weft thread at a measurement point and the measured
arrival moment of at least one weft thread at this measurement point exceeds a predetermined
threshold. A number of measurement points can be defined, wherein each measurement
point can be chosen in the shed and/or at the end of a shed. According to an embodiment,
an unwinding moment of a weft thread, for example at a prewinder, and an arrival moment
at a measurement point, for example at an exit of the shed, are measured and a time
difference is determined. According to an example, the time difference is determined
between a signal of the last but one winding, i.e. in case of five windings the fourth
winding, and the signal of the arrival of a weft thread at a detector which is mounted
at the exit of the shed. Alternatively or additionally the time difference is determined
between a last winding, in this example the fifth winding, and the arrival of a weft
thread at the said detector. I n case of a constant speed of the weft thread, each
of these two time differences is essentially constant. When the weft thread speed
decreases towards the end of the shed, one or each of the said time differences will
increase, so there can be concluded that the weft thread is not supported sufficiently.
[0019] According to a preferred embodiment, an average arrival moment for a certain number
of insertions is determined and a weaving error is detected if the time difference
between an expected arrival moment of an inserted weft thread at a measurement point
and the average arrival moment at this measurement point exceeds a predetermined threshold.
Preferably, a number of weft thread insertions that is used for determining an average
arrival moment is adjusted to a deviation between values measured during different
insertions as described in
WO 2006/114187.
[0020] According to another embodiment, an unstable weft thread insertion is identified
upon reaching at least one pre-set limit value for the standard setting. In determining
an unstable weft thread insertion upon reaching a limit for the standard setting for
the sets of relay nozzles the supply of compressed air to main nozzle device can be
reduced, in particular, the moment for interrupting an air supply to the main nozzle
device can be advanced in the weaving cycle. After reducing the air supply to the
main nozzle device, the supply of compressed air to the sets of relay nozzles can
be further reduced, in particular the moment of interrupting an air supply to the
sets of relay nozzles can be advanced in the weaving cycle. This allows a further
reduction of air supply to the sets of relay nozzles until the weft thread insertion
becomes unstable again.
[0021] Preferably, the setting for a compressed air supply to the main nozzle device and/or
to the at least one set of relay nozzles is adjusted when the average speed of inserted
weft threads is changed, in particular is slackened. I n order to compensate a change
of the average speed of weft thread insertions, a blowing force, i.e. a pressure and/or
an air current per time unit, of a main nozzle device can be changed. Methods for
compensating changes in an average speed are described for example in
WO 2007/071350. When weaving with certain yarn types, in particular with filament yarns, a weft
thread speed increases when weaving off a bobbin. This increase can be compensated
by a reduction of a blowing force. In other cases the average speed of the weft thread
slackens. In accordance with the methods described in
WO 2007/071350, a pressure and/or an air current per time unit increases or slackens in response
to this, in order to keep the average insertion speed or arrival of the weft thread
at a measurement point at an essentially constant level. I n order to avoid conflicts
between both regulating ways, one method can be interrupted or stopped under certain
conditions. For example, an adjustment of the standard settings for an air supply
can be stopped if a limit value for an applied pressure and/or air current per time
unit is reached.
[0022] According to still a further embodiment, the weaving speed of the weaving machine
is adjusted in accordance with a standard setting for a compressed air supply to the
main nozzle device and/or to the at least one set of relay nozzles, for example as
described in
WO 2007/071350. Again, in order to avoid conflicts between a method for regulating the weaving speed
in order to compensate changes in an average weaving speed and the adjustment according
to the invention, one of both methods can be interrupted or stopped under certain
conditions. For example, an adjustment of the standard settings for an air supply
can be stopped if a limit value for the weaving speed is reached.
[0023] The object is also solved by an airjet weaving machine provided with a main nozzle
device and at least one set of relay nozzles, wherein the airjet weaving machine comprises
a device for applying a method for adjusting standard settings for a compressed air
supply to the main nozzle device and the at least one set of relay nozzles.
[0024] Preferably the airjet weaving machine comprises a device with a control unit and
a number of shut-off valves which can be controlled by the control unit. The shut-off
valves allow a regulation of an air supply, in particular an interruption of an air
supply to certain sets of relay nozzles and/or the main nozzle device.
[0025] The main nozzle device preferably comprises a fixed main nozzle or auxiliary main
nozzle and a moveable main nozzle.
[0026] Further characteristics and advantages of the invention will appear from the following
description of example embodiments presented in the drawings and from the dependent
claims.
- Figure 1
- shows a schematic view of a part of an airjet weaving machine according to the invention.
- Figure 2
- shows a graphic of a standard setting for the supply of compressed air to the main
nozzle device and to successive sets of relay nozzles.
- Figure 3
- shows a graphic for an adjusted standard setting for the supply of compressed air
to the main nozzle device and successive sets of relay nozzles.
- Figure 4
- shows a graphic for a further adjusted standard setting for the supply of compressed
air to the main nozzle device and successive sets of relay nozzles.
- Figure 5
- shows a graphic for another further adjusted standard setting and an actual setting
for the supply of compressed air to the main nozzle device and successive sets of
relay nozzles.
- Figure 6
- shows a graphic for an adjusted standard setting for the supply of compressed air
to the main nozzle device at a further adjusting moment.
- Figure 7
- shows a graphic for an adjusted standard setting and an actual setting for the supply
of compressed air to successive sets of relay nozzles at another further adjusting
moment.
[0027] Figure 1 shows a device for transporting or inserting a weft thread through a schematically
indicated shed 1 of an airjet weaving machine. This device comprises two supply channels
2, 3 for the supply of a weft thread 4 or 5, respectively. Each supply channel 2,
3 comprises a thread buffer 6, a prewinder 7, and a main nozzle device 70 which comprises
a main nozzle 8 and an auxiliary main nozzle 9. The main nozzle 8 and the auxiliary
main nozzle 9 are mounted in series next to the shed 1, in particular the main nozzle
8 is mounted near the shed 1, while the auxiliary main nozzle 9 precedes the main
nozzle 8 according to the moving direction of the weft thread. The main nozzle 8 is
also called the second or moveable main nozzle, and the auxiliary main nozzle 9 is
also called the first or fixed main nozzle. Further the airjet weaving machine comprises
a reed 10 wherein a guide channel 40 is provided which allows a weft thread to be
transported through the shed 1 via this guide channel 40 by means of compressed air.
Near this guide channel 40, successive sets of relay nozzles 11, 12, 13, 14, 15, 16,
17, 18 and 19 are mounted along the shed 1, in particular mounted along the guide
channel 40 in order to successively support a weft thread making use of compressed
air.
[0028] The main nozzles 8 are each connected to a compressed air source 23 via associated
shut-off valves 21 and throttle valves 22. The auxiliary main nozzles 9 are each connected
to a compressed air source 23 via associated shut-off valves 24 and throttle valves
25. Each set of relay nozzles 11, 12, 13, 14, 15, 16, 17, 18 and 19 is connected in
a similar way via a shut-off valve 31, 32, 33, 34, 35, 36, 37, 38, 39 and an associated
throttle valve 26 to the compressed air source 23. According to a not shown variant
the throttle valves 26 can be omitted. The compressed air source 23 can comprise at
least one compressed air reservoir associated to respective nozzles. In addition,
a stretching nozzle 27 is shown which serves to keep a weft thread stretched once
this is inserted. The stretching nozzle 27 is connected to a compressed air source
23 via a shut-off valve 28 and a throttle valve 29. At the end of the guide channel
40 which is situated opposite the end, on which the main nozzles 8 are mounted, a
thread detector 41 is mounted which is equipped for determining when a weft thread
4, 5 arrives or passes at this thread detector 41.
[0029] The shut-off valves 21, 24, 28, 31, 32, 33, 34, 35, 36, 37, 38 and 39 and the throttle
valves 22, 25, 26 and 29 are controlled by a control unit 42 of the airjet weaving
machine, as illustrated in figure 1. The shut-off valves are for example electromagnetic
valves which can be controlled by the control unit 42. I n this case, the throttle
valves can be designed such that they can be driven by a motor and controlled by the
control unit 42. A device 71 for applying the method according to the invention comprises
at least the control unit 42 and a number of said shut-off valves.
[0030] A weft thread 4, 5 is blown into the guide channel 40 by a main nozzle 8 and is then
blown further along the guide channel 40 by jets of compressed air from sets of relay
nozzles 11 to 19. The guide channel 40 is for example mounted in a reed 10 and is
brought in a known way into a shed during the insertion of a weft thread 4, 5. At
the end of the guide channel 40 a thread detector 41 is arranged to detect the arrival
of a weft thread. The main nozzles 8, the sets of relay nozzles 11 to 19, the stretching
nozzle 27, the reed 10 and the thread detector 41 are attached in a known way on a
not shown sley which moves to and fro. The thread buffer 6, the prewinders 7 and the
auxiliary main nozzles 9 are attached on the frame of the airjet weaving machine.
[0031] The thread detector 41 is for example connected to a control unit 43 by means of
a connecting line 44. The control unit 43 is connected to the control unit 42 by means
of a connecting line 45. According to a not illustrated variant, the control unit
42 and the control unit 43 can be part of one single control unit. The shut-off valves
and the throttle valves are connected to the control unit 42 by means of a common
connecting line 50. Each prewinder 7 comprises a magnetic pin 46 in order to release
a desirable length of weft thread 4 or 5 at a desired moment. The magnetic pins 46
are connected to the control unit 42 by means of a common connecting line 49.
[0032] Figure 1 also shows next to each prewinder 7 a thread detector 47, which thread detector
47 sends a signal to the control unit 43 each time a winding 48 is unwound from a
wind-up drum of a prewinder 7, more in particular each time a part of a weft thread
arrives at or passes along the thread detector 47. Such a thread detector 47 is also
called a winding sensor. The signals of the thread detectors 47 are in this case guided
to the control unit 43 via a connecting line 57. The measurements on the transported
weft thread 4, 5 during the transport of this weft thread 4, 5 are obtained here by
the signals of the thread detector 47. Herewith, the moment when a winding 48 arrives
at a thread detector 47 is measured with respect to a reference moment, more in particular
what is known as winding time. For example, the moment when a winding 48 passes at
a thread detector 47 is measured with respect to the moment when the magnetic pin
46 is activated to release the weft thread 4 or 5 and this moment can be indicated
as the winding time. The successive signals of a thread detector 47 can be used as
measurements on the transported weft thread 4, 5 during its transport. Herewith it
is possible to measure or determine an absolute time for unwinding one or more windings.
[0033] Optionally, a number of thread detectors 54, 55, 56 can be mounted along the guide
channel 40 in order to detect when a leading end of the weft thread arrives at one
of these thread detectors. The thread detectors 54, 55, 56 can cooperate with the
control unit 43 via a connecting line 51.
[0034] As indicated in figure 1, the airjet weaving machine also comprises an input unit
52 which makes it possible to input several parameters. The control unit 42 is provided
to display parameters by means of a display unit 53. The connecting lines 49, 50,
51 and 57 can be for example CAN-bus lines.
[0035] While a weft thread 4, 5 is transported through the shed 1, the shut-off valves 21,
24, 31 to 39 are for example activated in accordance with the diagram as illustrated
in figure 2. I n this case the shut-off valves 31 to 39 are activated successively.
With airjet weaving machines it is customary to weave at a weaving speed in the order
of magnitude of 800 to 1200 weft threads per minute or, expressed differently, for
example with a weaving width of two meters, 1400 to 2800 meters per minute. When weaving
irregular weft threads, for example when weaving spun weft insertions, it is possible
that, with successive weft threads coming from a supply channel 2 or 3, a measured
insertion parameter differs considerably from weft thread to weft thread, in other
words that a particular weft thread arrives at a thread detector at a different moment
in the weaving cycle.
[0036] Figure 2 shows, by means of blocks 61 to 69, the periods in which the nine sets of
relay nozzles 11 to 19, indicated as BB11 to BB19, respectively, are provided with
compressed air, in other words, periods wherein the shut-off valves 31 to 39 of figure
1 are open in order to supply compressed air to an associated set of relay nozzles
11 to 19. The periods, in which the main nozzle 8 and the auxiliary main nozzle 9
are provided with compressed air are indicated respectively by blocks 20 and 30, indicated
as MMN8 and FMN9, respectively. Such blocks are explained in more detail in
WO 2007/057217. The blocks 20, 30 and 61 to 69 determine a moment for commencing the air supply
and a moment for interrupting the air supply to respective nozzles. In figure 2 the
time is indicated as angular positions 0 to 360 degrees of the main shaft of the weaving
machine. Each angular position corresponds with a moment in the weaving cycle, in
other words each angular position corresponds with a time in the weaving cycle.
[0037] In figure 2, line 58 illustrates the movement path of an average weft thread, line
59 illustrates the movement path of a fast weft thread and line 60 illustrates the
movement path of a slow weft thread. The lines 58, 59 and 60 can be determined during
the weaving of a large number of weft threads at a standard setting of the sets of
relay nozzles according to figure 2, for example a few thousands of weft threads.
A moment TG is a determined reference moment in the weaving cycle, for example a specific
chosen time after the weaving machine has reached a specific angular position in the
weaving cycle. The meaning of TG will be explained in more detail below.
[0038] If the weaving is done with a weaving machine which is set to a predetermined or
initial standard setting of interruption moments and/or periods according to figure
2 and the method according to the invention is activated, preferably the predetermined
standard setting according to figure 2 is adjusted automatically to an adjusted predetermined
standard setting according to figure 3, hereafter called "adjusted standard setting".
With this "adjusted standard setting" the supply of compressed air to at least one
specific set of relay nozzles is interrupted earlier in the weaving cycle than in
accordance with the initial standard setting according to figure 2.
[0039] A preferred adjusted standard setting with a belly pattern is shown in figure 3.
According to the standard setting shown in figure 3, a setting for a central set of
relay nozzles, i.e. set of relay nozzles 15 in the embodiment shown in figure 1, is
adjusted by shortening a period of air supply with 5%. The periods of air supply for
the two sets of relay nozzles adjacent to the central set of relay nozzles, i.e. sets
of relay nozzles 14 and 16, are shortened with 3%. The periods of the next sets of
relay nozzles, i.e. sets of relay nozzles 13 and 17 are only shortened with 1% and
the periods for the side sets of relay nozzles, i.e. sets of relay nozzles 11, 12,
18 and 19 are not shortened at this adjustment moment. The shortened air supply periods
are indicated in figure 3. For the sake of clearness, the standard setting according
to figure 2 before the adjustment is indicated with dashed lines in figure 3.
[0040] For example can in a similar way as described in
WO 2007/057217, in case of a slow weft thread, i.e. a weft thread which for example arrives at a
measurement point after the moment TG, this slow weft thread will be inserted with
a setting as illustrated in figure 2, while a normal or fast weft thread will be inserted
with a setting according to figure 3.
[0041] According to the invention a standard setting is adjusted and a stability of a weft
thread insertion is observed. When the weft thread insertion seems to be stable after
an adjustment step, a further adjustment of the actual standard setting can be carried
out. When the weft thread insertion is found to be unstable, an executed adjustment
is cancelled and/or the standard setting is adjusted in the opposite direction. So,
standard settings for an air supply to the sets of relay nozzles 11 to 19 and/or the
main nozzles 8, 9 are optimized.
[0042] According to a preferred embodiment, in order to optimize the compressed air supply,
with an adjusted standard setting the supply of compressed air to the fixed or auxiliary
main nozzle 9 is decreased. Preferably a decrease of the compressed air supply to
the auxiliary main nozzle 9 is accomplished by shortening a period of air supply as
indicated in dash-dot-line for block 20 in figure 3. It is preferred not to reduce
the period of the supply of compressed air to the main nozzle 8, in order to guide
the weft thread suitably to the shed at the entrance of the shed.
[0043] When the weft thread insertion remains stable despite a decrease of the period of
air supply to the at least one set of relay nozzles 11 to 19 and/or the main nozzles
8 and/or 9 of the main nozzle device 70, the period of compressed air supply to the
at least one set of relay nozzles 11 to 19 and/or the main nozzles 8 and/or 9 of the
main nozzle device 70 can be further decreased. Herewith or as an alternative the
compressed air supply to the sets of relay nozzles 11 to 19 can be further decreased.
Preferably the decrease of the compressed air supply to the sets of relay nozzles
11 to 19 is accomplished with settings which have a belly pattern.
[0044] Figures 4 and 5 show schematically a second and a third adjustment moment according
to an embodiment of the invention, wherein an interruption time is advanced in the
weaving cycle with respect to a setting as shown in figure 2. For the sake of clearness,
the standard setting of figure 2 before the adjustment is indicated with dashed lines
in figures 4 and 5. As mentioned above in a first moment the "standard setting", as
shown in figure 3, can be applied. If the weft thread insertion remains stable, the
interruption times for an air supply to the sets of relay nozzles 11 to 19 are further
advanced. I n the embodiment shown in figures 4 and 5 an interruption time for a central
set of relay nozzles, i.e. set of relay nozzles 15 in the embodiment shown in figure
1, is adjusted by shortening a period of air supply with 10% or 15% with respect to
the example of figure 2 at respectively a second or third adjustment moment. The period
of air supply for the sets of relay nozzles next to central set of relay nozzles,
i.e. sets of relay nozzles 14 and 16, are shortened with 6% and 9% with respect to
the example of figure 2 at respectively a second and third adjustment moment. The
period of air supply to the next sets of relay nozzles, i.e. sets of relay nozzles
13 and 17 is shortened with 2% and 3% with respect to the example of figure 2 at respectively
a second and third adjustment moment, and the period for the sets of relay nozzles
at the sides, i.e. sets of relay nozzles 11, 12, 18 and 19 are not shortened at all.
The decreased air supply periods are indicated in figures 4 and 5. Of course, other
belly patterns can be applied. When after the adjustment with an applied standard
setting in accordance with figure 5 is carried out, an unstable weft thread insertion
is detected, according to a method not in accordance with the invention the standard
setting can be reset to a previous standard setting, for example to the standard setting
as illustrated in figure 3. According to a variant, the standard setting according
to figure 5 can hereby be reset to the standard setting as illustrated in figure 4.
[0045] For example, in a similar way as described in
WO 2007/057217, in case of a slow weft thread, i.e. a weft thread that for example arrives at a
measurement point after the moment TG, this slow weft thread will be inserted with
a setting as illustrated with dash-dot-line for blocks 64, 65 and 66 in figure 5,
while a normal or fast weft thread will be inserted with the standard setting according
to figure 5.
[0046] I n accordance with the invention, as illustrated in figure 6, if an unstable weft
thread insertion is detected when a standard setting in accordance with figure 5 is
applied, the instability can be avoided by decreasing the blowing period of the auxiliary
main nozzle 9. For block 20 in figure 6 that illustrates the blowing period for the
auxiliary main nozzle 9, the decreased blowing period is indicated with full lines,
while the initial blowing period is indicated with dashed lines. More in particular,
the moment in the weaving cycle or the point of time for interrupting the compressed
air supply to the auxiliary main nozzle 9 can be advanced. An adjustment is accomplished
for example in dependency of the average deviation of the time difference between
the arrival of the weft thread at the end of the shed, measured by the thread detector
41, and the moment of detection of the last winding measured at the thread detector
47. The moment of the arrival of the weft thread at the end of the shed is also called
arrival time TA. The detected moment of the last winding at the thread detector 47
is also called the last winding time TLW.
[0047] According to an embodiment, a function for an adjustment of an interruption moment
for the auxiliary main nozzle 9 can be chosen with 50% of a deviation of the present
difference between the arrival time TA and the last winding time TLW with respect
to the initial standard setting. For example, if the time difference TA - TLW = 1
msec was indicated for an initial standard setting, and for the adjusted standard
setting, the time difference is TA - TLW = 3msec, the blowing time of the auxiliary
main nozzle 9 can be shortened with 50% of (3 - 1)msec or 1 msec. In other words,
in this example, the interruption time of the auxiliary main nozzle 9 is advanced
with 1 msec in the weaving cycle. This advancement of the interruption moment can
be based on average time differences and for taking the average a method similar as
described in
WO 2006/114187 can be applied.
[0048] Alternatively to the above mentioned example the blowing time of the auxiliary main
nozzle 9 can be shortened in steps of 0.5 msec until the value TA-TLW reaches about
1 msec again. According to still another alternative the blowing time of the auxiliary
main nozzle 9 can be shortened in steps of 5% of the blowing time of the auxiliary
main nozzle 9 until the value TA-TLW reaches a desired value again.
[0049] When after such an adjustment, the weft thread insertion is not stabilized a further
shortening of the blowing time of the auxiliary main nozzle 9 can be carried out.
If the weft thread insertion is stabilized, the blowing time for the sets of relay
nozzles 11 to 19 can be shortened further. For example, by decreasing the blowing
time of the auxiliary main nozzle 9, the blowing time for the sets of relay nozzles
11 to 19 can be further shortened with a belly pattern with for example an adjustment
of 30% at the central set of relay nozzles 15, as illustrated in figure 7. In the
embodiment of figure 7 the blowing time of the set of relay nozzles 12 are shortened
too.
[0050] If an instability of the insertion occurs at this setting, again either the setting
for the sets of relay nozzles 11 to 19 and/or the setting for the main nozzle device
70, in particular the auxiliary main nozzle 9 can be adjusted to a previous standard
setting.
[0051] According to an embodiment, an unstable weft thread insertion is identified upon
reaching at least one pre-set limit value.
[0052] Further, for the auxiliary main nozzle 9, a maximum decrease of a blowing time can
be set on 20% with respect to the initial standard setting or any other value of the
initial blowing time. Preferably, limit ranges are set in advance, for example when
choosing a low influence of the main nozzle device 70, a limit before the decrease
can be set on 15%, and when choosing an average or high influence, the limit for the
decrease can be set on 20% or 25%, respectively.
[0053] For example, in order to observe the stability of a weft thread insertion, an arrival
time at one or more of the weft thread detectors 41, 47, 54, 55, 56 can be measured
and a measured arrival time can be compared with an expected arrival time for an inserted
weft thread. If a time difference between the measured time and the expected time
exceeds a threshold, it can be assumed that a weaving error may have occurred and
that the weft thread insertion is unstable.
[0054] According to an embodiment, an unwinding time of a weft thread at the prewinders
7 and an arrival time at the exit of the shed 1, are measured by means of thread detectors
47 and 41, respectively, and a time difference is determined. If the time difference
exceeds a threshold, it may be assumed that an error has occurred and that the weft
thread insertion is unstable.
[0055] In order to avoid measurement errors and unstable adjustments, average arrival times
for a certain number of insertions are determined and a weaving error is assumed when
the time difference between an expected arrival time for an inserted weft thread at
a measurement point and the average arrival time at this measurement point exceeds
a predetermined threshold.
[0056] As mentioned above, slow weft threads and fast weft threads can be distinguished
by weaving according to a method according to
WO 2007/057217. Based on measurements on a particular transported weft thread, the supply of compressed
air can be interrupted later than specified by the applied standard setting, if it
has been determined that a relatively slow weft thread is transported through the
shed 1. In this case, the period during which compressed air is supplied to a number
of sets of relay nozzles during transport of a slow weft thread is extended with respect
to the applied standard setting.
[0057] For example, it is possible to determine the time or the period by which the supply
of compressed air will be extended based on the time difference between for example
a predetermined moment TG and a moment on which for example a certain winding is detected
which passes along the thread detector 47. The moment TG is a pre-set time or threshold
value with respect to a reference moment in the weaving cycle, for example a specific
chosen time after the moment on which the weaving machine has reached a certain angular
position in the weaving cycle or for example a specific chosen moment in the weaving
cycle that passes a certain winding normally at the thread detector. With this purpose
the moment TG can be entered via the input unit 52 in the control unit 42, optimized
by the control unit 42 or adjusted manually by the operator in a way as explained
in
WO 2007/057217.
[0058] In an embodiment as illustrated in figure 7 it is assumed that a weft thread has
a length of five windings, wherein the signals for the windings are t1w, t2w, t3w,
t4w and t5w, respectively, and for example the signal of the second winding t2w, in
other words the second signal of the thread detector 47, is used in order to control
the interruption of the compressed air supply to a certain set of relay nozzles. In
this case, the moment of the signal of the second winding t2w will be compared with
the moment TG in the weaving cycle.
[0059] If this measured signal of the second winding t2w occurs after the moment TG in the
weaving cycle, i.e. a relative slow weft thread is inserted, the compressed air supply
will be interrupted later to a set of relay nozzles 13 to 17, for example the period
can be extended to the actual setting as indicated in dash-dot-lines in figure 7.
I n other words, the supply of compressed air to a set of relay nozzles is extended
and an interruption is delayed with respect to the adjusted standard setting indicated
in full lines in figure 7. This extended supply can take place in a way as explained
in
WO 2007/057217.
[0060] According to a variant, as also explained in
WO 2007/057217, slow weft threads can be inserted with an adjusted standard setting for interrupting
the compressed air supply, for example the standard setting of figure 6, while normal
or fast weft threads can be inserted with an actual setting wherein the interruption
of the compressed air supply is advanced to an earlier moment in the weaving cycle,
for example to a moment earlier in the weaving cycle than the moment of the standard
setting of figure 6.
[0061] When this measured signal of the second winding t2w occurs at or before the moment
TG in the weaving cycle, i.e. a normal or relative fast weft thread is inserted, the
compressed air supply to a set of relay nozzles 13 to 17 will be interrupted according
to the predetermined applied standard setting, as illustrated in full lines in figure
7.
[0062] It is clear that a set of relay nozzles may consist of at least one single relay
nozzle or a number of relay nozzles connected to a compressed air source via an associated
shut-off valve. The devices for the supply of compressed air can be any device which
can set, control or adjust the supply of compressed air. As is known from
EP 442.546 B1 or
WO 2006/077063, the regulating of the compressed air supply to a main nozzle 8 or to an auxiliary
main nozzle 9 can comprise the operation of the throttle valves 22 and 25 in such
a way that each weft thread arrives, for example at average the same moment in the
weaving cycle, for example at a thread detector 41. This means for example that irrespective
of changes in the properties of successively inserted weft threads, which can for
example be the case with filament weft threads, the line 58 indicated in figure 2
for the movement path of an average weft thread does not change for successive weft
threads.
[0063] The invention allows to adjust in successive steps a standard setting so that the
moment for interrupting the air supply to the at least one set of relay nozzles 11
to 19 and/or to at least one main nozzle 8, 9 of the main nozzle device 70 is advanced.
The successive adjustment of the standard setting can stop, if either an instability
of the insertion is determined, if a limit for the advancement of the interruption
for at least one set of relay nozzles is reached, for example 30%, 40%, 50% or 60%
for the central set of relay nozzles, and/or if a limit for the advancement of the
interruption for a main nozzle is reached, for example 15%, 20% or 25% for the fixed
main nozzle 9. If the invention for example is applied in combination with a method
according to
WO 2007/071350 the adjustment of the standard setting can stop, if the value for the pressure and/or
the air current per time unit reaches for example 98% of its maximum value and/or
if the speed of the weaving machine during carrying out the method according to the
invention falls with a certain percentage, for example a percentage of 3% or 5%.
[0064] If an above mentioned limit of 30% for the central set of relay nozzles is provided,
for example the method according to the invention can be applied in steps of 5% towards
a limit value of 40%. If with 40% still no instability occurs, can be limited again
to the set limit value of 30%. In this case the adjusted standard setting is reset
to the standard setting of two adjustments before, which herewith corresponds with
the limit of 30%. If in this case with 35% an instability occurs, it can be reset
as security or certainty to 25% or two adjustments before, notwithstanding with the
limit of 30% no instability was observed yet.
[0065] Of course, the invention is not limited to the use of standard settings as illustrated
in figures 2 to 7, but other standard settings can be set. According to a possibility
in the control unit 42 for example can being entered to which set of relay nozzles
adjustments are possible, for example to the set of relay nozzles 17. This means that
the settings of the sets of relay nozzles 17, 18 and 19 are not adjusted according
to the invention. There can also be entered from which set of relay nozzles adjustments
of the standard setting are possible, for example from the set of relay nozzles 13.
This means that the settings of the sets of relay nozzles 11 and 12 cannot be adjusted
according to the invention. According to another possibility for example can be entered
or avoided that the settings cannot be adjusted for a certain set of relay nozzles
according the invention.
[0066] It is clear that adjusting the standard setting does not have to be done necessarily
with steps of 5%, 3% or 1%, but that the adjustments can be carried out in various
ways, for example according to various functions that are saved for example in the
control unit 42.
[0067] According to a not illustrated variant the standard settings for controlling the
shut-off valve 28 for the stretching nozzle 27 can also be determined and adjusted
according to a method according to the invention.
[0068] Each graphic in accordance with figures 2 to 7 for the supply of compressed air to
the above-mentioned successive sets of relay nozzles is expressed in angular degrees
of the main shaft of the weaving machine. When the speed of the weaving machine is
known, each graphic can be easily converted to time units, e.g. milliseconds.
[0069] The method according to the invention has the advantage that the air consumption
is appropriately decreased. In accordance with the invention, there can be saved most
compressed air by interrupting the sets of relay nozzles which are arranged approximately
near the centre of the shed more early with respect to the initial setting than the
sets of relay nozzles outside the centre.
[0070] It is clear that the airjet weaving machine is not limited to an airjet weaving machine
wherein a weft thread is blown into a guide channel 40 by means of compressed air.
The sets of relay nozzles of the airjet weaving machine can also blow onto a holder
for a weft thread which transports a weft thread through the shed. In addition, instead
of ordinary compressed air, any desired fluid can be used for inserting a weft thread
into a shed of a weaving machine of this type. In this case, it is also possible to
use ordinary compressed air mixed with a gas, a liquid or a vapour.
[0071] It is clear that irrespective of the fact that the present description mentions time,
this time can also be expressed in angular degrees of the weaving machine. I n this
case, one angular degree of the weaving machine corresponds for example with a number
of milliseconds or one millisecond corresponds with a number of angular degrees.
[0072] It is clear that the method according to the invention can be used for the insertion
of each of the weft threads 4 or 5. Herewith, for each weft thread 4 or 5 an individual
graphic for the supply of compressed air to the successive sets of relay nozzles and/or
to the main nozzle device 70 can be provided. The graphics for inserting each weft
thread can be different of one another, in particular if the weft threads 4 or 5 are
woven at a different weaving speed or transporting speed. This is particularly applied
when the speed of the weaving machine is adjusted to the weft thread to be inserted.
Of course, the method according to the invention can also be applied if one or more
than two different types of weft thread are used.
[0073] The method and the airjet weaving machine in accordance with the invention presented
in the claims are not restricted to the as example given embodiments which have been
shown and described, but can also include variants and combinations thereof which
fall within the scope of the claims.
1. Method for inserting a weft thread (4, 5) into a shed of an airjet weaving machine
comprising a main nozzle device (70) and at least one set of relay nozzles (11 to
19),
wherein
- a standard setting for a supply of compressed air to the main nozzle device and
to the at least one set of relay nozzles (11 to 19) is determined,
- the standard setting for the supply of compressed air to the main nozzle device
(70) and to the at least one set of relay nozzles (11 to 19) is adjusted in order
to reduce the supply of compressed air,
- a stability of the weft insertions with the adjusted standard setting is observed,
and
- the standard setting for the supply of compressed air to the main nozzle device
(70) and to the at least one set of relay nozzles (11 to 19) is adjusted such that
the supply of compressed air to the at least one set of relay nozzles (11 to 19) is
decreased until a weft insertion becomes unstable,
characterized in that
if a weft thread insertion becomes unstable when an adjusted standard setting for
the supply of compressed air to the main nozzle device (70) and to the at least one
set of relay nozzles (11 to 19) is applied, the supply of compressed air to the main
nozzle device (70) is decreased, in order to avoid the instability.
2. Method according to claim 1, characterised in that after the supply of compressed air to the main nozzle device (70) has been decreased,
the standard setting is further adjusted by decreasing the supply of compressed air
to the at least one set of relay nozzles (11 to 19).
3. Method according to claim 1 or 2, characterised in that for adjusting the standard setting an interruption of the supply of compressed air
to the main nozzle device (70) and/or to the at least one set of relay nozzles (11
to 19) is adjusted in function of measurements on the inserted weft threads (4, 5).
4. Method according to one of claims 1 to 3, characterised in that the main nozzle device (70) is provided with a first main nozzle (9) and a second
main nozzle (8), wherein the supply of compressed air to the first main nozzle (9)
is decreased, when a weft insertion becomes unstable.
5. Method according to one of claims 1 to 4, characterised in that a number of successive sets of relay nozzles (11 to 19) is provided, wherein the
standard setting for a compressed air supply to the number of sets of relay nozzles
(11 to 19) is adjusted making use of a belly pattern.
6. Method according to one of claims 1 to 5, characterised in that an unstable weft thread insertion is identified by detection of at least one weaving
error.
7. Method according to claim 6, characterised in that a weaving error is detected when the time difference between a measured moment wherein
an inserted weft thread (4, 5) arrives at a first measurement point and a measured
moment wherein the inserted weft thread (4, 5) arrives at a second measurement point
exceeds a predetermined threshold.
8. Method according to claim 6 or 7, characterised in that a weaving error is detected when the average time difference between a measured moment
wherein an inserted weft thread (4, 5) arrives at a first measurement point and a
measured moment wherein the inserted weft thread (4, 5) arrives at a second measurement
point exceeds a predetermined threshold.
9. Method according to one of claims 1 to 8, characterised in that an unstable weft thread insertion is identified upon reaching at least one pre-set
limit value for the standard setting.
10. An airjet weaving machine provided with a main nozzle device (70) and at least one
set of relay nozzles (11 to 19), characterised in that the airjet weaving machine comprises a device (71) which applies a method according
to any one of claims 1 to 9.
11. The airjet weaving machine according to claim 10, characterised in that the device (71) comprises a control unit (42) and a number of shut-off valves (21,
24, 28, 31 to 39) which can be controlled by the control unit (42).
12. The airjet weaving machine according to claim 10 or 11, characterised in that the main nozzle device (70) comprises a fixed main nozzle (9) and a moveable main
nozzle (8).
1. Verfahren zum Eintragen eines Schussfadens (4, 5) in ein Webfach einer Luftdüsenwebmaschine,
umfassend eine Hauptdüseneinrichtung (70) und mindestens einen Satz von Hilfsdüsen
(11 bis 19), wobei
- eine Standardeinstellung für eine Zufuhr von Druckluft zu der Hauptdüseneinrichtung
und zu dem mindestens einen Satz von Hilfsdüsen (11 bis 19) bestimmt wird,
- die Standardeinstellung für die Zufuhr von Druckluft zu der Hauptdüseneinrichtung
(70) und zu dem mindestens einen Satz von Hilfsdüsen (11 bis 19) angepasst wird, um
die Zufuhr von Druckluft zu reduzieren,
- eine Stabilität der Schusseinträge mit der angepassten Standardeinstellung überwacht
wird, und
- die Standardeinstellung für die Zufuhr von Druckluft zu der Hauptdüseneinrichtung
(70) und zu dem mindestens einen Satz von Hilfsdüsen (11 bis 19) so angepasst wird,
dass die Zufuhr von Druckluft zu dem mindestens einen Satz von Hilfsdüsen (11 bis
19) verringert wird, bis einen Schusseintrag instabil wird,
dadurch gekennzeichnet, dass
wenn bei Anwendung einer angepassten Standardeinstellung für die Zufuhr von Druckluft
zu der Hauptdüseneinrichtung (70) und zu dem mindestens einen Satz von Hilfsdüsen
(11 bis 19) ein Schussfadeneintrag instabil wird, dann wird die Zufuhr von Druckluft
zu der Hauptdüseneinrichtung (70) verringert, um die Instabilität zu vermeiden.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass nachdem die Zufuhr von Druckluft zu der Hauptdüseneinrichtung (70) verringert wurde,
die Standardeinstellung durch Verringern der Zufuhr von Druckluft zu dem mindestens
einen Satz von Hilfsdüsen (11 bis 19) weiter angepasst wird.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass zur Anpassung der Standardeinstellung eine Unterbrechung der Zufuhr von Druckluft
zu der Hauptdüseneinrichtung (70) und/oder zu dem mindestens einen Satz von Hilfsdüsen
(11 bis 19) in Funktion von Messungen an den eingetragenen Schussfäden (4, 5) angepasst
wird.
4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass die Hauptdüseneinrichtung (70) mit einer ersten Hauptdüse (9) und einer zweiten Hauptdüse
(8) versehen ist, wobei die Zufuhr von Druckluft zu der ersten Hauptdüse (9) verringert
wird, wenn einen Schusseintrag instabil wird.
5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass eine Anzahl aufeinanderfolgender Sätze von Hilfsdüsen (11 bis 19) vorgesehen ist,
wobei die Standardeinstellung für eine Druckluftzufuhr zu der Anzahl an Sätzen von
Hilfsdüsen (11 bis 19) mit Hilfe eines bauchigen Musters angepasst wird.
6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass ein instabiler Schussfadeneintrag durch Erfassung von mindestens einem Webfehler
identifiziert wird.
7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, dass ein Webfehler erfasst wird, wenn die Zeitdifferenz zwischen einem gemessenen Moment,
wobei ein eingetragener Schussfaden (4, 5) an einem ersten Messpunkt ankommt, und
einem gemessenen Moment, wobei der eingetragene Schussfaden (4, 5) an einem zweiten
Messpunkt ankommt, einen vorbestimmten Schwellwert überschreitet.
8. Verfahren nach Anspruch 6 oder 7, dadurch gekennzeichnet, dass ein Webfehler erfasst wird, wenn die durchschnittliche Zeitdifferenz zwischen einem
gemessenen Moment, wobei ein eingetragener Schussfaden (4, 5) an einem ersten Messpunkt
ankommt, und einem gemessenen Moment, wobei der eingetragene Schussfaden (4, 5) an
einem zweiten Messpunkt ankommt, einen vorbestimmten Schwellwert überschreitet.
9. Verfahren nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass ein instabiler Schussfadeneintrag bei Erreichen mindestens eines voreingestellten
Grenzwertes für die Standardeinstellung identifiziert wird.
10. Luftdüsenwebmaschine versehen mit einer Hauptdüseneinrichtung (70) und mindestens
einem Satz von Hilfsdüsen (11 bis 19), dadurch gekennzeichnet, dass die Luftdüsenwebmaschine eine Einrichtung (71) enthält, welche ein Verfahren nach
einem der Ansprüche 1 bis 9 anwendet.
11. Luftdüsenwebmaschine nach Anspruch 10, dadurch gekennzeichnet, dass die Einrichtung (71) eine Steuereinheit (42) und eine Anzahl an Absperrventilen (21,
24, 28, 31 bis 39) enthält, die durch die Steuereinheit (42) gesteuert werden können.
12. Luftdüsenwebmaschine nach Anspruch 10 oder 11, dadurch gekennzeichnet, dass die Hauptdüseneinrichtung (70) eine feste Hauptdüse (9) und eine bewegbare Hauptdüse
(8) enthält.
1. Procédé pour insérer un fil de trame (4, 5) dans une foule d'une machine à tisser
à jet d'air comprenant un dispositif buse principale (70) et au moins un jeu de buses
auxiliaires (11 à 19), dans lequel
- un réglage standard pour une alimentation en air comprimé vers le dispositif buse
principale et vers l'au moins un jeu de buses auxiliaires (11 à 19) est déterminé,
- le réglage standard pour l'alimentation en air comprimé vers le dispositif buse
principale (70) et vers l'au moins un jeu de buses auxiliaires (11 à 19) est ajusté
pour réduire l'alimentation en air comprimé,
- une stabilité des insertions de trame avec le réglage standard ajusté est observée,
et
- le réglage standard pour l'alimentation en air comprimé vers le dispositif buse
principale (70) et vers l'au moins un jeu de buses auxiliaires (11 à 19) est ajusté
de telle sorte que l'alimentation en air comprimé vers l'au moins un jeu de buses
auxiliaires (11 à 19) est diminuée jusqu'à une insertion de trame devient instable,
caractérisé, en ce que
si une insertion d'un fil de trame devient instable lorsqu'un réglage standard ajusté
pour l'alimentation en air comprimé vers le dispositif buse principale (70) et vers
l'au moins un jeu de buses auxiliaires (11 à 19) est appliqué, l'alimentation en air
comprimé vers le dispositif buse principale (70) est diminuée pour éviter l'instabilité.
2. Procédé selon la revendication 1, caractérisé en ce qu'après l'alimentation en air comprimé vers le dispositif buse principale (70) a été
diminuée, le réglage standard est en outre ajusté en diminuant l'alimentation en air
comprimé vers l'au moins un jeu de buses auxiliaires (11 à 19).
3. Procédé selon la revendication 1 ou 2, caractérisé en ce que pour ajuster le réglage standard une interruption de l'alimentation en air comprimé
vers le dispositif buse principale (70) et/ou vers l'au moins un jeu de buses auxiliaires
(11 à 19) est ajustée en fonction des mesures sur les fils de trame (4, 5) insérés.
4. Procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce que le dispositif buse principale (70) est prévu d'une première buse principale (9) et
une seconde buse principale (8), dans lequel l'alimentation en air comprimé vers la
première buse principale (9) est diminuée, lorsqu'une insertion de trame devient instable.
5. Procédé selon l'une quelconque des revendications 1 à 4, caractérisé en ce qu'un nombre de jeux successifs de buses auxiliaires (11 à 19) est prévu, dans lequel
le réglage standard pour une alimentation en air comprimé vers le nombre de jeux de
buses auxiliaires (11 à 19) est ajusté en utilisant un rapport de bombement.
6. Procédé selon l'une quelconque des revendications 1 à 5, caractérisé en ce qu'une insertion d'un fil de trame instable est identifiée par détection d'au moins une
erreur de tissage.
7. Procédé selon la revendication 6, caractérisé en ce qu'une erreur de tissage est détectée lorsque la différence de temps entre un moment
mesuré dans lequel un fil de trame (4, 5) inséré arrive à un premier point de mesure
et un moment mesuré dans lequel le fil de trame (4, 5) inséré arrive à un second point
de mesure dépasse un seuil prédéterminé.
8. Procédé selon la revendication 6 ou 7, caractérisé en ce qu'une erreur de tissage est détectée lorsque la différence de temps moyenne entre un
moment mesuré dans lequel un fil de trame (4, 5) inséré arrive à un premier point
de mesure et un moment mesuré dans lequel le fil de trame (4, 5) inséré arrive à un
second point de mesure dépasse un seuil prédéterminé.
9. Procédé selon l'une quelconque des revendications 1 à 8, caractérisé en ce qu'une insertion d'un fil de trame instable est identifiée en atteignant au moins une
valeur limite pré-réglée pour le réglage standard.
10. Une machine à tisser à jet d'air prévue d'un dispositif buse principale (70) et au
moins un jeu de buses auxiliaires (11 à 19), caractérisée en ce que la machine à tisser à jet d'air comprend un dispositif (71) qui applique un procédé
selon l'une quelconque des revendications 1 à 9.
11. La machine à tisser à jet d'air selon la revendication 10, caractérisée en ce que le dispositif (71) comprend une unité de commande (42) et un nombre de soupapes d'arrêt
(21, 24, 28, 31 à 39) qui peuvent être commandées par l'unité de commande (42).
12. La machine à tisser à jet d'air selon la revendication 10 ou 11, caractérisée en ce que le dispositif buse principale (70) comprend une buse principale (9) fixe et une buse
principale (8) mobile.