BE1024064B1 - A method of detecting a weft yarn in a jet loom of the air jet type. - Google Patents

Abstract

A method for detecting a weft yarn in a loom including a photoelectric weft detector for generating a detection signal, including the step of setting a first detection period between a time corresponding to the start of the loom insertion of weft yarn and a moment corresponding to the crossing of the warp yarn and a second detection period within the first period, with the exception of a mixed period. The method includes the step of providing a first threshold for a first detection signal generated during the first period, a second threshold for a second signal generated during the second period, and the step of determining an arrival normal to the detector when the first signal is equal to or greater than the first threshold and when the second signal is equal to or greater than the second threshold.

Description

Method of detecting a weft yarn in an air jet type loom

BASIS OF THE INVENTION

The present invention relates to a method for detecting a weft yarn in an air jet type loom.

An air jet type loom includes a weft yarn detecting device which is disposed on one side of a woven fabric opposed to the side corresponding to insertion of the weft yarn, or an opposite location to a fi insertion nozzle! of weft relative to a fabric to determine whether a weft yarn inserted by the weft insertion nozzle has arrived at the location indicated above at the appropriate time. Japanese Patent Application Publication H10-325053 discloses an air jet loom having a reflection type weft detector which is disposed between warp yarns and a selvage yarn on one side of the woven fabric opposite the weft insertion nozzle and which includes a light emitter and a light receiver.

In the air jet type loom of the publication cited above, the light emitter and the light receiver of the weft detection device are mounted on a protruding portion whose width dimension of the air jet type loom is less than that of a conventional weft yarn detection device in order to reduce weft yarn loss caused by the size of the yarn detecting device. weft, when measuring on the weaving width. The light emitter and the light receiver are arranged side by side in the direction perpendicular to the width direction of the weave so as to reduce the width of the projecting portion.

Reducing the size of the weft detection device in the width direction of the weave is effective in reducing the length of a weft yarn for use in a weft insertion cycle. For a subsequent reduction in the length of the fi! it is preferable to reduce the distance between the weft detection device and the warp yarns and the edge yarns.

However, the light emitted by the light emitting element of the weft detection device spreads to a certain extent. When the distance between the weft detection device and the warp yarns and selvedge yarns is reduced, the weft detection device is more able to detect the warp yarns and the selvedge yarns. which are arranged near the weft detection device. Despite the fact that no weft yarn reaches the detection position, the weft detection device may erroneously determine that a weft yarn is present, since a signal is generated by detecting warp threads or selvage threads.

In order to avoid such erroneous detection of a weft yarn, the moment corresponding to the end of the weft detection period may be advanced to prevent the weft detection device from detecting warp threads and selvage threads. However, the arrival times of the weft yarn at the detection position may vary, even under the same weft insertion conditions, depending on the variable thickness of a weft yarn fed from a coil or a winding of weft yarn.

Such variation in the arrival timing of the weft yarn may cause the weft detection device to fail to appropriately detect the weft yarn that has been successfully inserted. When the successfully inserted weft yarn fails to be appropriately detected, it is not immune to a false determination that the insertion of the weft yarn has not occurred. unsuccessful and the jet loom can be shut down accordingly. EP 0204093 discloses a method of detecting weft yarn in a jet loom using a type of light reflection of a weft detection apparatus.

The present invention, which is based on the problems described above, consists in providing an air jet type loom which makes it possible to reduce false detections by a photoelectric type weft sensor.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there is provided a method for detecting a weft yarn in an air jet type loom, the air jet type loom including a weft yarn sensor. of the photoelectric type at a location opposite to the weft insertion nozzle with respect to a fabric, wherein the photoelectric type weft sensor is arranged to generate a detection signal for detecting the weft yarn. The method includes: the step of setting a first detection period between a time corresponding to the start of the insertion of the weft thread and a time corresponding to the passage of the thread; of a warp and a second detection period within the first weft detection period except for a mixed detection period in which the photoelectric type weft sensor can detect a warp and / or a selvedge wire; the step of setting a first threshold for a first detection signal generated during the first detection period; and the step of setting a second threshold for a second detection signal generated during the second detection period. The method further includes the step of determining a normal arrival of weft yarn at the position occupied by the photoelectric type yarn sensor when the first detection signal for the first detection period corresponds to the first threshold or is greater than the latter and when the second detection signal for the second detection period corresponds to the second threshold or is greater than the latter. Other aspects and advantages of the invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an air jet type loom in which the position of a photoelectric type weft sensor is shown in which a method for the detection is implemented. a weft yarn according to a first embodiment of the present invention;

Fig. 2 is a schematic view of a display screen of a display device, in which the detection periods and the detection thresholds of the photoelectric type weft sensor are shown;

Fig. 3 is a diagram showing the relationship between the setting and the detection signals of the photoelectric type weft sensor;

Fig. 4 is a diagram showing the relationship between the detection time period and the photoelectric type raster sensor detection signal according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a first embodiment of the present invention is described with reference to Figs. 1 to 3. Referring to Fig. 1, there is shown a jet loom of the air jet type, specifically Sa part of the air jet type loom opposite to a weft yarn insertion nozzle (not shown) which inserts a weft yarn Y into a weft yarn guiding passage 4.

The air jet type loom includes a leaf 1 which is attached to an oscillating shaft (not shown) by a wing rod (not shown) so as to reciprocate back and forth in the direction of rotation. and away from the loom. A comb 2 which has a number of teeth 2A is mounted on the wing 1 and has a weft guideway 4 which is open towards a draw line 3. A device acting as a templet 7 is disposed between one side of the woven fabric 5 and a selvedge 6.

Weft yarns which are arranged between the woven fabric 5 and the selvedge 6 after their passage in front of the device 7 acting as a templet are cut by a blade 8. Several secondary nozzles 9 are mounted on the leaf 1 at intervals to convey the weft yarn Y through the weft guiding passage 4,

A photoelectric type weft sensor 10 is disposed on the leaf 1 at a predetermined detecting position between the warp yarns 11 for the woven fabric 5 and the selvedge yarns 12 for the selvedge 6. Specifically, the Photoelectric type weft sensor 10 is disposed at a location opposite to the weft insertion nozzle with respect to a fabric so as to detect a weft yarn. The photoelectric type weft sensor 10 includes a light emitter including a light emitting element and a light receiver including a light receiving element (neither of which is shown). The light emitter and the light receiver may be arranged in a side-by-side relationship along the guiding passage 4 for the weft yarn or perpendicular to the passage in question.

In the present embodiment, the photoelectric type weft sensor 10 is arranged in such a way that both the light emitter and the light receiver are opposed to the weft guide channel 4 in comb 2. The photoelectric type of weft sensor 10 is of the reflective type in which the light emitted by the light emitter is reflected by a weft yarn before being received by the light receiver. In addition, the photoelectric type of weft sensor 10 is adapted to generate a detection signal in the form of a pulse signal to a controller 13 to be described later. When the leading end of a weft yarn Y arrives at the position occupied by the photoelectric type weft sensor 10 opposite the weft insertion nozzle with respect to a fabric, the receiver The photoelectric type frame wire sensor light receives light which is reflected by the weft yarn Y, the weft yarn Y being detected by the weft sensor 10 of the photoelectric type.

Although the photoelectric type of weft sensor 10 of the present embodiment is of the reflection type, it is also possible to use a transmission type photoelectric sensor, in which a light emitter and a light receiver are arranged facing to face through the weft guiding guide passage at 4, and the light receiver receives the light emitted by the light emitter in the absence of a weft yarn in the passage.

The photoelectric type weft sensor sensor light receiver 10 is electrically connected to the control device 13 of the air jet type loom via a signal processing device (not shown). by using a transmission wire 14, the light receiving signal provided by the light receiver is compared with a threshold value predefined in terms of sensitivity and is transformed into a pulse signal (detection signal) by the processing device signal, then said pulse signal being sent to the controller 13. The controller 13 determines whether or not the leading end of the weft yarn Y has arrived at the pickup location of the feed wire. frame by counting the number of pulse signals sent by the weft sensor 10 of the photoelectric type. The controller 13 determines that insertion of the weft yarn takes place without any problem when weft yarn Y is detected and the air jet type loom continues its weaving operation. The controller 13 determines a failure of the weft insertion when no weft yarn is detected and the air jet type loom interrupts its weaving operation.

A display device 16 is electrically connected to the controller 13 via a wire 15. The display device 16 has an input device (not shown) that is used to input various data required for operation. of the air jet type loom and a display screen 17 (as can be seen in FIG. 2) on which various data stored in the control device 13 and processed by the latter are displayed.

A weft thread tensioner 18 is disposed in a lateral position outside the selvedge 6 and the edge thread 12. The weft thread tensioner 18 includes a drawing nozzle 19 which is arranged at the front of the comb 2 or on the receiving side of the woven fabric 5, a weft catcher pipe 20 which is arranged at the rear of the comb 2 or on the side corresponding to the unwinding of the warp threads 11 and a removal nozzle of weft thread 21. The weft thread tensioner 18 is configured to stretch and hold the leading end of a weft yarn Y so as to exert a predetermined tension on the weft yarn Y.

Referring to Fig. 2, there is shown a display screen 17 of the display device 16 on which various settings concerning the detection of a weft yarn Y by the weft sensor 10 of the photoelectric type are displayed. The setting data is pre-established and is stored in the controller 13. In the controller 13, a first detection period PI and a second detection period P2 are set which corresponds to the duration and detection of the weft yarn. by the photoelectric type weft sensor 10 for the weft yarn types A.

In order for the controller 13 to be able to determine correctly whether a pulse signal from the photoelectric type of weft sensor 10 indicates the presence or absence of a weft yarn Y, a first threshold S1 and a second threshold S2 in terms of sensitivity for both the first detection period PI and for the second detection period P2, respectively for the signals in the control device 13. The first detection period PI is set between the moment corresponding to the start of the insertion of weft thread and the moment corresponding to its passage through the warp thread. The first threshold S1 is set for a first detection signal generated during the first detection period P1 and the second threshold $ 2 for a second detection signal generated during the second detection period P2. As described above, the first detection signal and the second detection signal represent a pulse signal according to the present embodiment.

In the present embodiment, the first threshold S1 for the first signa! in the first detection period PI and the second threshold S2 for the second detection signal in the second detection period P2 are set to six pulse signals and two pulse signals, respectively. Specifically, it is determined that a weft yarn Y is present when at least six pulse signals and at least two pulse signals are sent by the weft sensor 10 of the photoelectric type during the first one. PI detection period and during the second detection period P2, respectively.

As can be seen in FIG. 2, the first threshold S1 for the first detection period PI and the second threshold $ 2 for the second detection period P2, introduced for the frame wires of types B and C, are the same as those for the type A weft yarn in the present embodiment. It should be noted that the settings for the Type B and C weft wires can be set differently from those for Type A weft wire.

The first detection period PI is set for the lapse of time between the time T1 corresponding to the start of the detection and the moment T4 corresponding to the end of the detection, and the number of the pulse signals sent by the wire detector. a photoelectric type frame 10 during the first detection period PI is used to determine the presence or absence of a weft yarn Y. The second detection period P2 is set for the lapse of time between time T2 corresponding to the start of the detection and the moment T3 corresponding to the end of the detection, and the number of the pulse signals sent by the photoelectric type of weft detector 10 during the second detection period P2 is used for the same object as indicated above. The moment T corresponding to the arrival of the weft yarn represents the arrival time of the front end of a weft yarn Y at the position occupied by the weft detector 10 of the photoelectric type.

The moment T3 corresponding to the end of the detection of the second detection period P2 is set to correspond to a moment within the first detection period PI at which the warp 11 and the selvedge wire 12 can not penetrate into. the detectable range of the photoelectric type weft detector 10, even when the warp 11 and the selvedge 12 are released. In the time interval P3 which extends from the moment T3 corresponding to the end of the detection of the second detection period P2 until the moment T4 corresponding to the end of the detection of Ια first detection period PI, one runs the risk that warp threads and / or a weft thread may not be detected. Such a period will be referred to as the mixed detection period P3. In other words, the second detection period P2 is introduced within the first detection period with the exception of the mixed detection period P3 during which the detection detector P1 is detected. of the photoelectric type of frame 10 can detect a warp 11 and / or an edge wire 12. The moment T2 corresponding to the start of the detection, of the second detection period P2 is set in such a way that located after the time T1 corresponding to the start of the detection, the first detection period PI.

It should be indicated that the time T2 corresponding to the start of the detection, the second detection period P2 can be set to correspond to any appropriate time. For example, the time T2 corresponding to the start of the detection can be set to be at the time T1 corresponding to the start of the detection, the first detection period PI, or at a time that precedes it.

Hereinafter, examples of the detection of a weft yarn by the weft detector 10 of the photoelectric type are described with reference to FIG. 3 in which various settings such as the first detection period PI and the second detection period P2. As shown in FIG. 2, the number of pulse signals for the first threshold S1 and for the second threshold S2 at six and two pulse signals, respectively, are set. The presence or absence of a weft yarn Y is determined by the controller 13 based on the number of detected pulse signals. Specifically, the controller 13 determines the presence of a weft yarn when the number of pulse signals detected during the first PI detection period, or the first detection signals for the first detection period. PI is equal to or greater than the first threshold $ 1 (six pulse signals), and when the number of pulse signals detected during the second detection period P2, or the second detection signals for the second detection period P2 is equal to or greater than the second threshold S2 (two pulse signals). In other words, the controller 13 is configured to determine a normal arrival of the weft yarn Y at the position occupied by the photoelectric weft detector when the weft detection conditions described above are met. .

Referring to Example 1, when the leading end of an inserted weft yarn Y arrives at the weft sensor 10 of the photoelectric type before the time T3 corresponding to the end of the detection, the second period of detection P2, a light emitted by the light emitter is reflected by the weft yarn Y and the reflected light is received by the light receiver. The photoelectric type weft detector 10 sends three pulse signals to the controller 13 in the period of time between the moment T corresponding to the arrival of the weft thread and the moment T3 corresponding to the end. detection, the second detection period P2. After the moment T3 corresponding to the end of the detection, the photoelectric type of weft detector 10 sends three additional pulse signals to the control device 13 at the moment T4 corresponding to the end of the detection, the first period of time. PI detection.

The control device 13 counts six DI pulse signals during the first detection period PI, this number being equal to or greater than the first threshold S1 (six signals), and three pulse signals D2 during the second period. detection P2, this number being equal to or greater than the second threshold S2 (two signals). Since the detection of the pulse signals DI and D2 corresponds to the detection conditions of the weft yarn, the control device 13 determines the presence of a yarn Y. In Example 2, the front end of a weft yarn Y arrives at the detector of fi! 10 of the photoelectric type prior to the moment T3 corresponding to the end of the detection, the second detection period P2, and three pulse signals D2 are sent in the lapse of time extending between the moment T corresponding to the arrival of the weft thread and the moment T3 corresponding to the end of the detection. Seven pulse signals are sent during the lapse of time extending between the moment T3 corresponding to the detection of the second detection period P2 and the moment T4 corresponding to the end of the detection of the first detection period PI,

The control device 13 counts ten pulse signals D3 during the first detection period P1 and three pulse signals D2 during the second detection period P2, this number being greater than the first and second thresholds S1 and S2, respectively. Since the detection of the pulse signals D2 and D3 by the photoelectric frame wire detector 10 meets the weft detection conditions, the controller 13 determines the presence of a weft yarn Y. In other words, the control device 13 determines a normal arrival of the weft yarn Y at the position occupied by the weft detector 10 of the photoelectric type when the first detection signal for the first detection period P1 is equal or greater than the first threshold S1 and when the second detection signal for the second detection period P2 is equal to or greater than the second threshold S2.

Although the pulse signal D3 includes ten pulse signals, i.e., a number greater than the number of pulse signals DI of Example 1, four pulse signals D4 which are detected near the time T4 corresponding to the end of the detection can be considered as signals indicating the detection of warp son 11 or edge son 12 in the mixed detection period P3. Such detection of warp yarns 11 and selvedge yarns 12 in Example 2, which is not encountered in Example 1, can be estimated as due to the presence of warp threads 11 and threads. selvedge 12 having an unexpected slack, giving rise to the entry of the warp threads and edge threads 12 into the detectable range of the photoelectric type weft detector 10 during the mixed detection period P3. In example 3, no pulse signal is sent by the photoelectric type of weft detector 10 during the second detection period P2. The photoelectric type weft detector 10 sends six pulse signals D5 to the controller 13 in the period T3 extending between the time corresponding to the end of the detection of the second defection period P2 and the moment T4. corresponding to the end of the detection of the first detection period PI.

The control device 13 has six pulse signals D5 during the first detection period P1, namely a number equal to or greater than the first threshold S1, but no pulse signal is counted during the second period. P2 detection. Since no pulse signal is generated during the second detection period P2 and six pulse signals D5 are generated after the moment T3 corresponding to the end of the detection of the second detection period P2 , or only during the mixed detection period P3, these six pulse signals are considered to indicate the detection of warp yarns 11 and edge yarns 12. Since the reception of the D5 pulse signals by the photoelectric type weft detector 10 does not respond to the weft detection conditions, the control device 13 determines that the weft yarn Y is absent and directly generates a signal to stop the operation of the weaving loom of the type with jet d'e'rr.

As described, the D5 pulse signals that are sent during the first PI detection period are considered to be due to the detection of warp yarns 11 and selfinch yarns 12 during the period of time. P3 mixed detection. Since the presence or absence of the Y-yarn is determined by the first PI detection period and the second P2 detection period, the detection of a Y-yarn can be effectively differentiated from the yarn detection. Thus, the present embodiment prevents erroneous detection by the photoelectric type weft detector 10 in an efficient manner. Example 4 is similar to Example 3, but here the detector of fi! 10 of photoelectric type frame sends a pulse signal D6 to the controller 13 during the second detection period P2. During the first PI detection period, the photoelectric-type frame sensor 10 sends six D5 pulse signals in the period between the time T3 corresponding to the end of the detection of the second detection period. P2 and the moment T4 corresponding to the end of the detection of the first detection period PI.

The six pulse signals D5 that are generated by the photoelectric-type frame wire detector 10 during the first detection period PI exceed the first threshold S1, but the only pulse signal D6 generated during the second P2 detection period is less than the second threshold $ 2. Since the detection of the pulse signals D5 and D6 does not meet the detection requirements of the weft yarn, the controller 13 determines that the yarn Y is missing and immediately generates a signal to stop the operation of the loom weaving machine of the air jet type.

The D5 pulse signals that are sent only during the mixed detection period P3 are considered to be due to the detection of the warp yarns 11 and the edge yarns 12, and the only D6 pulse signal sent during of the second detection period P2, which is equal to or less than the second threshold S2, is considered to be due to the detection of dust. Accordingly, it is possible to prevent erroneous detection of the photoelectric type weft detector 10 caused by the detection of warp threads 11, selvedge threads 12 and dust.

According to the present embodiment, it is possible to prevent erroneous detection by the photoelectric-type weft detector 10 while allowing an arrangement of the photoelectric-type weft detector 10 as close as possible to the warp yarns 11 and selvedge son 12 in a loom of the air jet type. Thus, such an arrangement of the photoelectric type weft detector 10 in the vicinity of the warp yarns 11 and the selvedge yarns 12 significantly reduces the consumption of the weft yarn Y which is not used in the woven fabric 5.

Hereinafter, a second embodiment of the present invention is described with reference to FIG. 4. For the objects of the description, like or similar parts or elements are designated by the same reference numerals or by the same symbols than those of their correspondents that were used in the first embodiment, and their destruction will be omitted. In contrast to the first embodiment, in which the controller 13 counts the number of pulse signals transformed from the light receiving signals of the weft detector 10 of the photoelectric type, the control device 13 of the second embodiment is configured to detect whether the time period during which the light receiving signal from a photoelectric type of weft detector is equal to or greater than one level. predetermined.

Referring to FIG. 4, the first detection period P1 and the second detection period P2 are set in the control device 13. In FIG. 4, a first high state period D7 represents a time period set in FIG. first detection period P1 during which the light reception signal is equal to or greater than a predetermined level and a second high state period D8 represents a period of time set in the second detection period P2 during which the signal of light reception is equal to or greater than a predetermined level.

The detection signals from the photoelectric type of weft detector 10 are considered to be high while the light receiving signals from the photoelectric type of weft detector 10 receive light. are generated by the detection of the weft thread, are equal to or greater than their respective predetermined level. Referring to Figure 4, the signa! in the first high state period D7 in the first detection period P1 and in the high state during the first frame detection period of the photoelectric frame wire detector 10 is high. the second high state period D8 in the second detection period P2.

According to the second embodiment, the first threshold is set for the first high state period D7 during which the first detection signal is generated and the second threshold is set for the second high state period D8 during from which the second detection signal is generated. The first detection signal is generated when the light receiving signal from the photoelectric-type frame wire detector 10 is equal to or greater than the predetermined level and the second detection signal is generated when the reception signal of the photoelectric type light is equal to or greater than the predetermined level. The controller 13 detects the first detection signal for the first high state period D7 in the first detection period PI and the second detection signal for the second high state period D8 in the second detection period P2. With the detection of the high state of the signal for the first and the second high state period D7, D8, from the photoelectric type of weft detector 10, which satisfies the detection conditions of a weft yarn , the control device 13 determines that a weft yarn Y is present. Although the first and second high state period D7, D8 are set as weft detection conditions according to the second embodiment, unlike the first and the second threshold S1, S2 for the number in the first embodiment, the second embodiment has the same effect as that of the first embodiment.

Claims (3)

CLAIMS]. A method for detecting a weft yarn (Y) in an air jet type loom, wherein the air jet type loom includes a weft yarn detector (10) photoelectric type at a location opposite a weft insertion nozzle with respect to a fabric (5), wherein the photoelectric type weft detector (10) is adapted to generate a signal detection device for detecting the weft yarn (Y), characterized in that it comprises: the step of setting a first detection period (PI) between a time T1 corresponding to the start of the insertion of the weft thread and a moment T4 corresponding to the crossing of a warp and a second detection period (P2), for the lapse of time between the moment T2 corresponding to the start of the detection and the moment T3 corresponding to the end of the defection, the moment T3 corresponding to the end of the detection of the second the detection period P2 is set to correspond to a moment within the first detection period PI at which the warp thread 11 and the edge thread 12 can not penetrate the detectable range of the weft thread detector 10 of the type photoelectric, even when the warp thread 11 and the selvedge wire 12 are released, the moment T2 corresponding to the start of the detection, the second detection period P2 can be set to correspond to any appropriate time, Ια second detection period within the first detection period (PI) with the exception of a mixed detection period (P3) during which the photoelectric-type frame detector (10) can detect a warp (11) and / or a selvedge wire (12); the time interval P3 which extends from the moment T3 corresponding to the end of the detection of the second detection period P2 until the moment T4 corresponding to the end of the detection of the first detection period P1, we run the there is a risk that warp and / or weft threads may not be detected, the step of setting a first threshold (SI, D7) for a first detection signal generated during the first detection period (PI ); the step of setting a second threshold (S2, D8) for a second detection signal generated during the second detection period (P2); the step of determining a normal arrival of the weft yarn (Y) at the position occupied by the photoelectric type weft detector (10) when the first detection signal for the first detection period (PI) is equal or greater than the first threshold (SI, D7) and when the second detection signal for the second detection period (P2) is equal to or greater than the second threshold ($ 2, D8), a photoelectric type of weft sensor 10 is disposed on the leaf 1 at a predetermined defection position between the warp threads 11 for the woven fabric 5 and the selvedge threads 12 for the selvedge 6. 2. Method according to claim 1, characterized in that each of the first detection signal and the second detection signal is a pulse signal, the first threshold (SI) and the second threshold ($ 2) being introduced by the number of pulse signals. 3. Method according to claim 1, characterized in that the first threshold (SI, D7) is set for a first high state period (D7) during which the first detection signal is generated and the second threshold (S2). , D8) is set for a second high state period (D8) during which the second detection signal is generated, wherein the first detection signal is generated when a light receiving signal from the light receiver the photoelectric type frame wire detector is equal to or greater than a predetermined level and the second detection signal is generated when the light receiving signal is equal to or greater than a predetermined level.