BACKGROUND OF THE INVENTION
[0001] The present invention relates to an air-jet loom. More specifically, the present
invention pertains to an air-jet loom that performs weft insertion through a passage
in the reed by means of blow of air from the main nozzle and auxiliary nozzles.
[0002] In this type of air-jet loom, the state of the weft yarn during weft insertion largely
depends on the pressure setting of pressurized air. Conventional, Japanese Laid-Open
Patent Publication No.
4-241135 discloses a pressure controlling device for weft insertion in an air-jet loom that
is capable of improving the consumption efficiency of discharged fluid, while cancelling
slack in the weft yarn in the latter half of weft insertion and reducing erroneous
picks in weft insertion. The control device detects the weft yarn unwinding finish
time in a device for measuring weft yarn measuring and storing weft yarn and the weft
yarn leading end arrival time, and controls the jet pressure of the main nozzle based
on the weft yarn leading end arrival time. Also, based on the difference between the
weft yarn leading end arrival time and the weft yarn unwinding finish time, the control
device controls the jet pressure of the main nozzle and the jet pressure of the auxiliary
nozzles. Specifically, when the difference between the detected weft yarn leading
end arrival time and the detected weft yarn unwinding finish time is greater than
a target value, the control device increases the jet pressure of the auxiliary nozzles.
When the time difference is less than the target value, the control device lowers
the jet pressure of the auxiliary nozzles.
[0003] When the weft insertion is performed by flying the weft yarn stored in the weft yarn
measuring and storing device through the passage in the reed, or the reed passage,
by air jet from the main nozzle and the auxiliary nozzles, a part of the weft yarn
Y closer to the trailing end undulate before the leading end of the weft yarn Y reaches
a predetermined position that corresponds to the completion of the weft insertion,
as shown in Fig. 6A. At the point in time close to the completion of the weft insertion,
the undulation is cancelled as shown in Fig. 6B, so that the weft insertion is performed
in a strained state of the weft yarn Y.
[0004] In a state in which the weft yarn leading end arrival point in time TW, which is
the time at which the weft yarn leading end reaches the end of the weft insertion
range, is maintained at a constant value, the relationship among the jet pressure
of the auxiliary nozzles (auxiliary pressure), the difference between the weft yarn
leading end arrival point in time TW and the weft unwinding finish point in time TBW
in the weft yarn measuring and storing device (TW - TBW), and the time at which the
weft yarn is strained is represented by the graph of Fig. 7. In Fig. 7, the angles
of TW and TBW represent rotation angles of the loom. As shown in Fig. 7, the loom
rotation angle at the time when the weft yarn Y is strained decreases as the auxiliary
pressure increases. That is, the higher the auxiliary pressure, the earlier the point
in time of straining becomes.
[0005] When determining the optimum jet pressure of the auxiliary nozzles at weft insertion,
a changing point of the difference between the weft yarn leading end arrival point
in time TW, which is the time at which the weft yarn leading end reaches the end of
the weft insertion range, and the weft unwinding finish point in time TBW in the weft
yarn measuring and storing device (TW - TBW), is used as one of the indications. In
this case, however, the state of the weft yarn in the warp shed is not directly monitored,
and the changing point is merely an alternative indication. It is thus impossible
to determine, based on the value of TW - TBW, the margin of the auxiliary pressure
for optimizing the point in time of straining. Therefore, when regulating the machine,
a stroboscope is used to visually check the state of the weft yarn, and the auxiliary
pressure is set, accordingly. However, in a cloth construction in which the top warps
are continuous, such as satin weaving, it is difficult in some cases to check the
state of the weft yarn in the warp shed using a stroboscope.
[0006] DE 41 42 356 A1 disclose a weft sensing monitoring system for a weaving machine. In particular, an
image sensor camera acts as a weft yarn position detector, and is arranged near a
weft guide groove of a reed.
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to provide an improved air-jet loom that
is adapted to monitor the state of a weft yarn flying through the reed passage and
display the timing at which the weft yarn is strained before the weft yarn leading
end arrival point in time.
[0008] The above object is solved by an air-jet loom having the features of claim 1. Further
developments are stated in the dependent claims.
[0009] Other aspects and advantages of the present invention will become apparent from the
following description, taken in conjunction with the accompanying drawings, illustrating
by way of example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The invention, together with objects and advantages thereof, may best be understood
by reference to the following description of the presently preferred embodiments together
with the accompanying drawings in which:
Fig. 1 is a schematic diagram showing a weft insertion device;
Fig. 2 is a schematic perspective view showing the main nozzle, the auxiliary nozzles,
and the weft yarn sensor;
Fig. 3 is a cross-sectional side view showing the positional relationship between
a dent and the weft yarn sensor;
Fig. 4 is a diagram showing the positional relationship between the reed passage,
the weft yarn, and a phototransmitter/receptor;
Fig. 5 is a diagram showing an output waveform of the sensor;
Fig. 6A is a diagram showing a state of the weft yarn before being strained;
Fig. 6B is a diagram showing a state of the weft yarn after being strained; and
Fig. 7 is a graph showing the relationship between the auxiliary pressure and the
weft yarn strained state.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] One embodiment of the present invention will now be described with reference to Figs.
1 to 5.
[0012] As shown in Figs. 1 and 2, an air-jet loom includes a main nozzle 11 used in weft
insertion, auxiliary nozzles 12 used in weft insertion, a reed 13, and a weft yarn
measuring and storing device 14 of a winding type. As shown in Fig. 2, the main nozzle
11, the auxiliary nozzles 12, and the reed 13 are fixed onto a sley 15. The reed 13
includes a plurality of dents 16 arranged in the direction of weft insertion. Each
dent 16 has a guide recess 16a (shown in Fig. 3). The guide recesses 16a of the dents
16 form a passage in the reed 13, or a reed passage 17.
[0013] As shown in Fig. 1, the main nozzle 11 is connected to a tank 19 for the main nozzle
11 via piping. The main nozzle tank 19 is connected to a source pressure tank 18.
An electromagnetic valve 20 is provided between the main nozzle 11 and the main nozzle
tank 19. Jet of pressurized air for weft insertion from the main nozzle 11 is controlled
by opening and closing the electromagnetic valve 20. An electric pressure control
valve 21 is provided between the source pressure tank 18 and the main nozzle tank
19. The pressure of the main nozzle tank 19 is regulated by the pressure control valve
21.
[0014] The auxiliary nozzles 12 are connected to a tank 22 for the auxiliary nozzles 12
via piping. The auxiliary nozzle tank 22 is connected to the source pressure tank
18. Electromagnetic valves 23, 24, 25, 26 are provided between the auxiliary nozzles
12 and the auxiliary nozzle tank 22. Jet of pressurized air for weft insertion from
the auxiliary nozzle tank 22 is controlled by opening and closing the electromagnetic
valves 23, 24, 25, 26. The electromagnetic valves 23 to 26 control the supply of pressurized
air to the auxiliary nozzles 12. The electromagnetic valves 23 to 26 are successively
controlled to be opened and closed, so that so-called relay jet is generated by the
auxiliary nozzles 12. An electric pressure control valve 27 is provided between the
source pressure tank 18 and the auxiliary nozzle tank 22. The pressure of the auxiliary
nozzle tank 22 is regulated by the pressure control valve 27.
[0015] The weft yarn measuring and storing device 14 has a thread winding face 14a. Winding
of a weft yarn Y onto the thread winding face 14a and unwinding of the weft yarn Y
from the thread winding face 14a are controlled by extension and retraction of a stopper
pin 28a of an electromagnetic solenoid 28. Excitation and de-excitation of the electromagnetic
solenoid 28 is performed through command control by a controller C. The controller
C controls de-excitation of the electromagnetic solenoid 28 based on information related
to unwinding of the weft yarn Y delivered by the weft yarn unwinding detector 29.
The weft yarn unwinding detector 29 detects unwinding of the thread wound onto the
thread winding face 14a.
[0016] Opening and closing of the electromagnetic valves 20 and 23 to 26 are controlled
through commands from the controller C. Based on a signal indicting a detected rotation
angle of the loom delivered from a rotary encoder 31, which detects the rotation angle
of the loom, the controller C controls opening and closing of the electromagnetic
valves 20 and 23 to 26 and excitation of the electromagnetic solenoid 28.
[0017] A pressure detector 32 is connected to the main nozzle tank 19, and a pressure detector
33 is connected to the auxiliary nozzle tank 22. Information of detected pressures
from the pressure detectors 32, 33 is delivered to the controller C. The controller
C feedback controls the pressure control valves 21, 27 based on the pressure information
from the pressure detector 32, 33.
[0018] As shown in Fig. 2, the auxiliary nozzles 12 are fixed onto the sley 15 with support
blocks 35. The auxiliary nozzles 12 can enter the shed of warp threads T through between
the rows of the warp threads T as the sley 15 swings.
[0019] A weft yarn detector 37 is fixed to the sley 15 with a support block 38 such that
the position of the weft yarn detector 37 is adjustable. The weft yarn detector 37
detects that the leading end of the weft yarn Y has reached the end of the range of
weft insertion. As shown in Fig. 1, the weft yarn detector 37 is electrically connected
to the controller C.
[0020] As shown in Figs. 2 and 3, an optical sensor 40 is fixed to the sley 15 via the support
block 38 such that the position of the optical sensor 40 is adjustable. The optical
sensor 40 detects the extent of slack of the weft yarn Y in a region close to the
main nozzle 11 in the reed passage 17. The region close to the main nozzle 11 in the
reed passage 17 refers to a region between the center of the reed passage 17 and the
main nozzle 11. The optical sensor 40 is located in a range where the optical sensor
40 can detect the extent of slack of the weft yarn Y without being influenced by the
jet pressure of the main nozzle 11.
[0021] As shown in Figs. 3 and 4, the optical sensor 40 is fixed to the sley 15 such that
the distal end of a support body 41 faces the reed passage 17. Also, the optical sensor
40 is fixed to the sley 15 such that, during the beat-up, the distal end of the support
body 41 moves in a space below a woven cloth W and a cloth fell W1 without interfering
with the woven cloth W or the cloth fell W1. The support body 41 has a tubular shape.
As shown in Fig. 4, a phototransmitter 42, which is a light-emitting diode, and a
photoreceptor 43, which is a phototransistor, are provided in the distal end of the
support body 41. The phototransmitter 42 and the photoreceptor 43 are electrically
connected to the controller C via lead wires 44.
[0022] The optical sensor 40 includes an output section. The output section outputs pulse
signals of different intervals depending on whether the optical sensor 40 detects
that the weft yarn Y is flying in an undulating state or that the weft yarn Y is flying
in a strained state based on an optical signal received by the photoreceptor 43. Specifically,
the optical sensor 40 uses a polarized light to convert, into a pulse, the changing
state of the signal representing the weft yarn Y from the photoreceptor 43 into a
pulse, and outputs the obtained pulse signal. As a result, as shown in Fig. 5, when
it is detected that the weft yarn Y is flying in an undulating state, the interval
of the pulse signal P is relatively short. When it is detected that the weft yarn
Y is flying in a strained state, the interval of the pulse signal P is relatively
long. In Fig. 5, the point in time at which the output interval of the pulse signal
P changes from the short interval to the long interval is referred to as the point
in time of straining.
[0023] A display device (not shown) is connected to the controller C. The controller C includes
a microcomputer and a memory. The controller C is configured to store, in the memory,
data representing the points in time of straining, which are calculated based on the
output state of the pulse signal shown in Fig. 5 for, for example, the last several
hundreds of times of weft insertion, and to successively renew the data with the latest
point in time of straining. The controller C displays on the screen either the points
in time of straining as numeric data represented by the loom rotation angles in the
last several times of weft insertion or the pulse waveforms in relation to the loom
rotation angles as shown in Fig. 5. The controller C functions as a determining means
that determines the time at which the weft yarn Y is strained prior to the weft yarn
leading end arrival time based on the output signal of the optical sensor 40.
[0024] Operation of the weft yarn detector of the air-jet loom as described above will now
be described.
[0025] When the air-jet loom is operating, the weft yarn detector emits polarized light
from the phototransmitter 42 of the optical sensor 40 toward the reed passage 17 and
receives the light reflected by the guide recesses 16a of the dents 16 using the photoreceptor
43. A detection signal of the photoreceptor 43 is converted into a pulse signal through
signal processing and output to allow detection of the state of the weft yarn Y flying
through the reed passage 17. If the weft yarn Y flying through the reed passage 17
at a part that faces the phototransmitter 42 and the photoreceptor 43 is undulating,
the interval of the output pulse signal is made short. If the weft yarn Y at the part
facing the phototransmitter 42 and the photoreceptor 43 is strained, the interval
of the output pulse signal is made long. As a result, at the point in time where the
undulating flying state of the weft yarn Y changes to the strained state, the pulse
signal interval changes from a short interval to a long interval as shown in Fig.
5.
[0026] For each weft insertion, the controller C stores, as the point in time of straining,
the loom rotation angle at which the short pulse signal interval changes to the long
pulse interval. From when a predetermined number of times of weft insertion have been
performed or from when a predetermined period of weft insertion time has elapsed,
the data of old points in time of straining starts being deleted and replaced by the
data of new points in time of straining. The controller C displays the values of the
loom rotation angles corresponding to the points in time of straining of a predetermined
number of times from the data sets stored in the memory. By seeing the displayed data,
the operator can easily check whether the weft insertion is being performed in a stable
manner and under preset conditions.
[0027] When the type of the weft yarn Y, the cloth width, or both of these are changed,
the compressed air discharged from the main nozzle 11 and the auxiliary nozzles 12
need to be adjusted. A this time, the auxiliary pressure of the auxiliary nozzles
12 is set to proper values by changing the pressure of compressed air discharged from
the auxiliary nozzles 12, while checking the information related to the strained state
of the weft yarn Y on the screen of the display device, which is connected to the
controller C. This way, the adjustment operation is facilitated compared to the case
in which strained state is checked using a stroboscope. If a stroboscope is used,
the state of the weft yarn in the warp shed is difficult to monitor visually in some
weaving conditions for example with a cloth construction in which the top warps are
continuous as satin weaving. Even in such a weaving operation, the present embodiment
allows the state of the weft yarn and the point in time of straining to be easily
checked.
[0028] The present embodiment achieves the following advantages.
- (1) The weft yarn detector is adapted to be used in an air-jet loom, in which weft
insertion of the weft yarn Y through the reed passage 17 is performed by air jet from
the main nozzle 11 and the auxiliary nozzles 12. The optical sensor 40 for detecting
the extent of slack of the weft yarn Y is located in the reed passage 17 at a position
close to the main nozzle 11. According to this configuration, the optical sensor 40
detects whether the weft yarn Y is flying through the reed passage 17 with a part
close to the trailing end either undulating or strained. Therefore, while monitoring
the state of the weft yarn Y flying through the reed passage, it is possible to display
the point in time at which the weft yarn Y is strained before the weft yarn leading
end arrival point in time.
- (2) The optical sensor 40 detects the extent of slack of the weft yarn Y in a range
that is not influenced by the jet pressure of the main nozzle 11. In the range that
is influenced by the jet pressure of the main nozzle 11, it is difficult to determine
whether the weft yarn Y is strained based on the detection signal of the optical sensor
40. However, if the extent of slack of the weft yarn Y is detected in the range that
is not influenced by the jet pressure of the main nozzle 11, whether the weft yarn
Y is in the strained state can be easily determined.
- (3) The optical sensor 40 outputs pulse signals of different intervals between when
the slack of the weft yarn Y is over a permissible range and when the slack is within
the permissible range. Accordingly, it is possible to determine whether the weft yarn
Y is strained by checking the pulse signal output by the optical sensor 40. Therefore,
the determination is done more easily than a case in which the strained state of the
weft yarn Y is determined based on the video picture of the flying weft yarn Y. Also,
since the time point at which the pulse interval of the pulse signal output by the
optical sensor 40 changes corresponds to the point in time of straining of the weft
yarn Y, the point in time of straining is also easily determined.
[0029] The present invention is not limited to the above described embodiment, but may be
embodied as follows, for example.
[0030] The controller C may issue a warning when determining that the point in time of straining
is out of a permitted range of a predetermined operational state of the loom based
on the data of the points in time of straining. As the method of warming, a warning
lamp may be lighted, or a warning tone may be produced.
[0031] The controller C may control the jet pressure of the auxiliary nozzles 12 when determining,
based on the data of the points in time of straining, that the point in time of straining
has continued to be outside the permitted range of the predetermined operational state
of the loom for a predetermined period of time or a predetermined number of times
of weft insertion. Also, a warning may be issued while the jet pressure of the auxiliary
nozzles 12 is controlled.
[0032] During operation of the loom, the controller C does not necessarily need to constantly
operate the weft yarn detector (the optical sensor 40) to check the data related to
the point in time of straining of the weft yarn Y and display the data. For example,
the weft yarn detector may check the data related to the point in time of straining
of the weft yarn Y and display the data only when activated by the operator. In this
case, since the weft yarn detector is activated only when the machine is regulated
or when the operator requires, the energy consumption by the weft yarn detector is
reduced.
[0033] The optical sensor 40 does not necessarily need to have independently constructed
phototransmitter 42 and photoreceptor 43, but may have an integrated phototransm itter/receptor.
[0034] The weft yarn detector may include two or more sensors at different positions in
the reed passage 17 to detect whether the weft yarn Y is present at the corresponding
positions. In this case, the point in time of straining is determined when a specific
one of the sensors outputs a signal indicating the presence of the weft yarn in a
stable manner.
[0035] The weft yarn detector may have a sensor detection area at a position of stable flying
of the weft yarn Y after the weft yarn Y is strained, and may determine the point
in time of straining when the weft yarn presence signal has been output for a predetermined
period of time.
[0036] The optical sensor 40 does not necessarily need to detect slack of the weft yarn
Y in a range that is not influenced by the jet pressure of the main nozzle 11, but
may detect slack in a range that is influenced by the jet pressure of the main nozzle
11, for example, at a position closest to the main nozzle 11.
[0037] The optical sensor 40 does not necessarily need to include the phototransmitter 42,
which emits polarized light, and the photoreceptor 43, which outputs a detection signal
to be converted to a pulse signal through signal processing. For example, a photoelectric
sensor having multiple phototransmitters/receptors may be employed. In this case,
the weft yarn is determined to be strained when a weft yarn presence signal from a
specific photoreceptor has continued to be output for a predetermined period of time.
[0038] The optical sensor 40 does not necessarily need to be configured such that a phototransmitter
and a photoreceptor arranged in the vicinity of the reed passage 17 are electrically
connected to a power source for the phototransmitter and a power source for the photoreceptor
by lead wires, respectively. For example, a phototransmitter and a photoreceptor may
be provided on the sley 15, and the phototransmitter and the photoreceptor may be
connected to ends of an optical fiber for the phototransmitter and an optical fiber
for the photoreceptor, respectively. In this case, the other ends of the optical fibers
are inserted into the support body 41 to face the reed passage 17. This configuration
allows the width of the support body 41 to be reduced compared to the configuration
in which a phototransmitter and a photoreceptor are provided in the support body 41.
[0039] An optical sensor may be employed in which phototransmitter optical fibers and photoreceptor
optical fibers are inserted into the support body 41. In this case, the distal ends
of the phototransmitter optical fibers and the photoreceptor optical fibers can be
easily arranged in the direction of vibrations of the weft yarn Y within the reed
passage 17.
[0040] Therefore, the present examples and embodiments are to be considered as illustrative
and not restrictive and the invention is not to be limited to the details given herein,
but may be modified within the scope and equivalence of the appended claims.
[0041] A weft yarn detector is adapted to be used in an air-jet loom, in which weft insertion
of a weft yarn through a reed passage is performed by air jet from a main nozzle and
auxiliary nozzles. An optical sensor for detecting the extent of slack of the weft
yarn is located in the reed passage at a position close to the main nozzle.
1. Luftdüsenwebmaschine, bei der ein Schussgarneinführen eines Schussgarns (Y) durch
einen Webblattkanal (17) mittels einem Luftstrahl von einer Hauptdüse (11) und einer
Vielzahl an Hilfsdüsen (12) für das Schussgarneinführen ausgeführt wird,
wobei die Luftstrahlwebmaschine gekennzeichnet ist durch:
eine Schussgarnpositionserfassungseinrichtung (37), die erfasst, dass ein Führungsende
des Schussgarns (Y) das Ende des Schussgarneinführbereichs erreicht hat; und
eine Schussgarndurchhängerfassungseinrichtung, die einen optischen Sensor (40) aufweist,
der das Ausmaß des Durchhängens des Schussgarns (Y) in einem Bereich des Webblattkanals
(17) zwischen der Mitte des Webblattkanals (17) und der Hauptdüse (11) erfasst.
2. Luftdüsenwebmaschine gemäß Anspruch 1, wobei der optische Sensor (40) in einem Bereich
des Webblattkanals (17) zwischen der Mitte des Webblattkanals (17) und einer der Hilfsdüsen
(12) angeordnet ist, die der Hauptdüse (11) am nächsten ist.
3. Luftdüsenwebmaschine gemäß Anspruch 1 oder 2, wobei der optische Sensor (40) Impulssignale
unterschiedlicher Intervalle in Abhängigkeit davon ausgibt, ob der optische Sensor
(40) erfasst, dass das Schussgarn (Y) in einem wellenartigen Zustand fliegt oder dass
das Schussgarn (Y) in einem gespannten Zustand fliegt.
4. Luftdüsenwebmaschine gemäß Anspruch 1 oder 2, die eine Bestimmungseinrichtung (C)
aufweist, die einen Zeitpunkt bestimmt, bei dem das Schussgarn (Y) gespannt ist vor
einer Schussgarnführungsendeintreffzeit auf der Basis eines Abgabesignals des optischen
Sensors (40).
5. Luftdüsenwebmaschine gemäß Anspruch 4, die eine Anzeigevorrichtung aufweist,
wobei die Bestimmungseinrichtung (C) zu der Anzeigevorrichtung Daten ausgibt, die
Zeitpunkte des Spannens des Schussgarns (Y) in einer Häufigkeit des Schussgarneinführens
zeigen, wobei die Daten durch Webmaschinendrehwinkel repräsentiert werden.
1. Métier à tisser du type à jet d'air, dans lequel l'insertion d'un fil de trame (Y)
via un passage de ros (17) est mise en oeuvre par un jet d'air émis par une buse principale
(11) et par un certain nombre de buses auxiliaires (12) pour l'insertion du fil de
trame, le métier à tisser du type à jet d'air étant
caractérisé par :
un détecteur de position du fil de trame (37) qui détecte qu'une extrémité avant du
fil de trame (Y) a atteint l'extrémité de la plage d'insertion du fil de trame ; et
un détecteur de mou de fil de trame comprenant un capteur optique (40) qui détecte
l'ampleur du mou du fil de trame (Y) dans une zone du passage de ros (17) entre le
centre du passage de ros (17) et la buse principale (11).
2. Métier à tisser du type à jet d'air selon la revendication 1, dans lequel le capteur
optique (40) est situé dans une zone du passage de ros (17) entre le centre du passage
de ros (17) et une des buses auxiliaires (12) qui est la plus proche de la buse principale
(11).
3. Métier à tisser du type à jet d'air selon la revendication 1 ou 2, dans lequel le
capteur optique (40) envoie des signaux d'impulsion de différents intervalles en fonction
du fait de savoir si le capteur optique (40) détecte que le fil de trame (Y) est en
train de voler dans un état ondulant ou le fait que le fil de trame (Y) est en train
de voler dans un état tendu.
4. Métier à tisser du type à jet d'air selon la revendication 1 ou 2, comprenant un moyen
de détermination (C) qui détermine un moment auquel le fil de trame (Y) est tendu
avant un moment d'arrivée de l'extrémité avant du fil de trame en se basant sur un
signal de sortie du capteur optique (40).
5. Métier à tisser du type à jet d'air selon la revendication 4, comprenant un dispositif
d'affichage, dans lequel le moyen de détermination (C) envoie, en direction du dispositif
d'affichage, des données qui représentent des moments de tension du fil de trame (Y)
au cours de plusieurs insertions de fil de trame, les données étant représentées par
des angles de rotation du métier à tisser.