EP1502979A1 - Method to control the weft transfer in a loom - Google Patents

Abstract

A weaving loom has a blade (1) with a light sensor (10) monitoring the position of a weft thread (4) during insertion. After the thread has been inserted and captured by a post (3), the blade advances the thread to the end-stop (7). During the blade advance the weft thread passes through the light sensor beam, causing a change in the quantity of light detected which is then converted into a signal pulse. If the signal pulse is absent at a pre-determined moment, or if its amplitude is outside a given range, the weft thread is faulty. The measurement is taken when insertion of the weft thread is complete in a projectile weaving loom or a rapier loom.

Description

The invention relates to a method for Weft thread monitoring in a weaving machine according to the preamble of claim 1.

There are various known systems that have a Allow monitoring of the weft in a loom. In particular, the weft thread with optical Be monitored means such as e.g. in DE-U-91 02 313 is disclosed. There is on the leaf of an air weaving machine a reflector arranged, which is irradiated by a light source becomes. Reflected by the reflector light is from measured by a detector. If the weft thread gets during passing through the compartment to the reflector, so is in the detector generates a signal.

It turns out, however, that with such a Method especially late in the machine cycle occurring errors can not be reliably measured. It is therefore the task, a procedure to provide the type mentioned that also detect errors occurring late in the machine cycle can.

This object is achieved by the method according to claim 1 solved. According to the invention, the measurement thus takes place only take place after the weft thread completely into the tray has been entered and moved against the sheet stop becomes. For this purpose, an optical sensor, in particular in Form a photocell, so arranged that the weft passes through the measuring range and or at least in this occurs while the sheet is against the stop emotional. This can e.g. be achieved by the Measuring range against the weft and / or the weft is moved against the measuring range. It is checked whether the weft thread the measuring range in a certain Target time range reached or traversed - if so is not the case, so can be closed on an error become.

Preferably, the measuring range is arranged that the weft thread is only detected when the Sheet is moved against the stop. This allows a late measurement.

The measuring range is during the weft insertion preferably offset laterally to the entry line of the weft, so that the weft during the entry in the subject is not recorded. Only after made entry, the weft thread passes in the course of his Move to stop laterally in the measuring range. Again, this allows a late measurement.

To get a relative movement between measuring range and weft yarn can generate the movement of the sheet and / or the movement of the thread. For this, e.g. a light transmitter and / or a light sensor and / or a mirror can be arranged on the sheet and move with the leaf. Be both light source as well as light sensor arranged on the sheet, so can the measuring range can be moved by the sheet and the Weft, for example, just before contact with the Capture leaf.

Preferably, the measuring range is at the beginning, at the end or in a gap, leaving under gap an area to understand, in which the distance between two successive warp threads much larger than that normal warp spacing is. In these places is relative a lot of space is available and the warp threads disturb the Measurement not.

Fig. 1 eine Webmaschine mit einer ersten Ausführung eines erfindungsgemässen Detektors,

Fig. 2 eine Seitenansicht des am Blatt montierten Sensors,

Fig. 3 eine Vorderansicht des Sensors alleine,

Fig. 4 eine Seitenansicht einer zweiten Ausführung des am Blatt montierten Sensors,

Fig. 5 eine Webmaschine mit einer dritten Ausführung eines erfindungsgemässen Detektors

Fig. 6 einen Schnitt durch den Sensorkopf der dritten Ausführung des Detektors,

Fig. 7 eine Seitenansicht der dritten Ausführung des am Blatt montierten Detektors.

Further preferred embodiments of the invention will become apparent from the dependent claims and from the following description with reference to FIGS. Showing:

1 shows a loom with a first embodiment of a detector according to the invention,

2 is a side view of the sensor mounted on the blade,

3 is a front view of the sensor alone,

4 is a side view of a second embodiment of the blade mounted sensor,

5 shows a weaving machine with a third embodiment of a detector according to the invention

6 shows a section through the sensor head of the third embodiment of the detector,

Fig. 7 is a side view of the third embodiment of the blade-mounted detector.

Figs. 1 and 2 show a portion of the weft arrival side a projectile loom. Visible, noticeable is the sheet 1 with a plurality of leaf bars 2 and a clamp 3 for the weft 4. Schematically represented is also the tray 5 and the already woven goods 6 with the sheet stop 7.

To monitor the weft thread is at the end of the sheet 1, an optical sensor 10 is provided. In the in Fig. 1 to 3 shown first embodiment consists of Sensor comprising a head part 20, a connecting part 21 and a foot part 22. The head part 20 is e.g. with a Clamped screw 23 on the upper crossbar 24 of the sheet 1 and the foot part 22 e.g. with a screw 25 am lower crossbar 26 of the blade 1. The connecting part 21 consists of an elongated plate and connects the Head part 20 with the foot part 22. It can e.g. as a printed circuit board be executed, the electrical connection lines 28 carries between the headboard 20 and foot part 22.

In the foot part 22, a light source 15 is arranged, a light beam 17 on a detector 19 in Headboard 20 throws. The sensor 10 thus forms a light barrier with a measuring range 27, which is between Light source 15 and detector 19 extends.

The sensor 10 and the measuring area 27 move with the sheet 1. In this case, the measuring area 27 is arranged such that that he is currently outside the subject, so that the warp threads are not in the measuring range 27 to step.

In operation of the loom is after the entry each weft in a known manner from the edge thread clamp 3 and one at the opposite, not shown End of the tray 5 arranged second Randfadenklemme recorded, depending on weaving machine and yarn type can also be dispensed with the terminals. As shown in FIG. 2, the sheet 1 now moves in the direction of the arrow S against the sheet stopper 7 of the goods 6. In this case enters the weft 4 in the measuring range 27 and traverses this, resulting in a change in the light detector 19 measured amount of light and thus to a corresponding Signal pulse leads.

With correct weft insertion and intact Weft, the signal pulse is always at the same time (i.e., at the same time in the machine cycle). If no signal pulse is detected at this time, so can thus closed on a mistake and a corresponding Error signal are generated, which is e.g. to stopping the machine.

In addition to the time of the signal pulse its length or duration can also be measured which is a measure of the time during which the Weft is located in the measuring range. This period of time is when the measuring area 27 transversely to the longitudinal direction of the Weft moves, a measure of the thickness of the weft. Instead of or in addition to the duration of the signal also the amplitude of the signal can be measured, which is also a measure of the cross section or the Diameter of the thread compared to the cross-sectional area of the measuring range. With both methods can thus a measure of the thread cross section or the thread thickness determined become.

If e.g. two weft threads entered at the same time so can the break of just one of the Threads are detected. If the weft in the This can also be done over the length or u.U. the amplitude of the signal pulse are measured since the weft in this case loses its tension and visually thicker or multi-layered in the measuring range to come to rest. In both cases, by comparison the measured time duration with a target time duration and / or by comparing the measured amplitude with a Target amplitude of the error can be determined.

For an accurate measurement of the thread thickness is the measuring range 27 not too thick to choose or in the detector 19 is an imaging optics to provide the Weft 4 in a suitable size ratio on the Light detector images.

For determining the desired time and the Target duration or amplitude of the signal pulse can Calibration measurements are carried out, e.g. during the normal operation of the loom can happen. For example can signal during several machine cycles recorded by the light detector and the waveform averaged over the cycles. Then you can Setpoint time, setpoint duration and setpoint time amplitude or a desired signal waveform determined from the averaged signal become. It is also possible, later waveforms e.g. by subtraction, division or correlation calculation to compare with the averaged waveform.

To get a strong signal regardless of the state of pollution the light source 15 and the detector 19, two measurements are preferably made. A first measurement takes place for a short time the expected time of the weft signal instead of and serves as a reference. During the expected time of Weft signal then becomes a measurement relative to this reference, e.g. by the weft signal is divided by the reference signal or the Reference signal from the weft signal is subtracted. Thus, e.g. the influence of permanent pollution the optical components are eliminated.

Fig. 4 shows a second embodiment of the inventive Sensor. Here are, as indicated by dashed lines, the light source 15 and the light detector 19, and a beam splitter 18 arranged in the foot part 22. The Light source 15 sends the light through the beam splitter 18th in the measuring range 27. It hits a reflector or Mirror 29, which is arranged on the head part 20. From there it is thrown back onto the beam splitter 18, from where a part is reflected on the light detector 19. These Design has the advantage that no electrical connection between foot and headboard is necessary. Possibly can also be dispensed with the connecting part 21 become.

In Fig. 5 to 7 is a third embodiment shown the thread monitor. Here, the optical includes Sensor 10 a stationary on the frame 11 of the loom arranged sensor head 12 and one arranged on the sheet 1 Reflector 13.

As can be seen in particular from FIG. 5, comprises the sensor head 12 a laser light source 15 ', which, optionally with appropriate optics 16, a bundled, essentially non-divergent light beam 17 generated, which generates the measuring area 27. The light beam 17 passes through a beam splitter 18 and then falls the reflector 13, where a light spot of preferably at most 1 mm in diameter is generated. The reflector 13 is retroreflective, i. its surface is like that, that he prefers to throw light back in the direction from which it arrives. Corresponding reflectors are used e.g. from the company 3M under the trade name 3M Scotchlite Diamond Grade offered.

The reflector is on the outermost leaf strut 2a of the sheet 1, i. at the entry direction seen last leaf strut, and indeed whose outside and thus outside of the compartment 5.

The reflected light from the reflector 13 occurs at least partially in turn onto the beam splitter 18, of where it is thrown onto a light detector 19 '.

In operation of the loom is after the entry each weft may be caught by the clamps. As can be seen from FIG. 7, this now moves Sheet 1 in the direction of the arrow S against the sheet stop 7 of the product 6, wherein pulled through a first position of the Blatts and dashed a later second position shown becomes. At the same time, the clamp 4 also moves Towards sheet stop 7. It sweeps over the Weft 4 at least part of the reflector thirteenth The components of the weft guard are arranged so that at least during a part of this movement the light beam 17 strikes the reflector 13, and that During this time, the weft 4 once moved by the light beam 17, resulting in a change the amount of light measured in the light detector 19 'and thus leads to a corresponding signal pulse.

The reflector is, as mentioned, on the side the last leaf strut 2a, in which the leaf stop 7 facing edge arranged, so he with the weft thread comes into contact. This leads to a continuous cleaning of the reflector and to a good Contrast ratio of the signal pulse.

In the described third embodiment are light source 15 ', beam splitter 18 and light detector 19 'arranged together in the sensor head 12. This results together with a retroreflective reflector particularly simple assembly, since only two components must be aligned with each other. In principle, can however, a diffuse reflector can also be used, wherein In this case, however, the measurement signal is weaker. It is also conceivable to use a reflective reflector, the reflected light beam practically not returned to the light source, but in this case Light source and detector very close to the reflector or must be mounted separately from each other, making the adjustment difficult.

It is also possible in the three above Embodiments described in addition or alternatively at the weft insertion side of the compartment 5 perform by using an appropriate sensor or reflector in the direction of insertion direction first leaf rod arranges. There is more space in both places than between The reeds and the warp threads disturb the light beam 17 not.

If several webs woven next to each other can, the measurement can also be in a gap of the sheet between two tracks.

The light source 15 or 15 'and / or the Lichtdektetor 19 can also be used as an optical waveguide be arranged with one arranged at another place Light transmitter or detector module connected are.

The method described here allows a Measuring the weft thread late in the machine cycle, to which the weft already completely entered the subject and the sheet is already moved against the leaf stop. Thus, too very late breaks or other errors are still detected.

It can be used for projectile looms, as well be used for rapier looms. In these Both types of weaving machine will be relatively strong against the sheet the weft moves, which, especially at a arranged on the sheet sensor, a good measurement allowed. Also, use with other weft insertion systems is however conceivable in itself.

Claims (18)

Method for monitoring the weft thread in a weaving machine, in which a weft thread (4), after being inserted into the compartment (5), is guided by the sheet (1) against the sheet stop (7) of the product (6), an optical sensor (10) being provided, with which the presence of the thread in a measuring area (27) is detected, characterized in that the measuring area (27) is arranged so that the weft thread (4) is fully inserted into the compartment (5) during the movement of the sheet (1) reaches and / or traverses the measuring area (27) against the stop, wherein it is checked whether the weft thread reaches and / or traverses the measuring area (27) in a set time range. Method according to one of the preceding claims, wherein the sensor (10) is a light barrier. Method according to one of the preceding claims, wherein the measuring area (27) is arranged so that the weft thread (4) enters it only when the Sheet (1) against the sheet stop (7) is moved towards. Method according to one of the preceding claims, wherein the measuring area (27) during the weft insertion laterally to an entry line of the weft thread is offset, so that the weft thread (4) during the entry in the compartment does not enter the measuring range (27). Method according to one of the preceding claims, wherein a light source (15) and / or a light detector (19, 19 ') and / or a reflector (13, 29) on Sheet (1) is arranged and moved by the sheet, and in particular that a light source (15) and a Light detector (19) on the sheet (1) are arranged. Method according to one of the preceding claims, wherein the measuring area (27) moves away from the sheet (1) becomes. Method according to one of the preceding claims, wherein on the sheet (1) arranged a reflector (13) is on which light (17) is blasted, wherein the Light (17) passes through a beam splitter (18) before it on the reflector (13) falls, and the reflected light also through the beam splitter (18) and then to a Light detector (19, 19 ') falls. Method according to one of the preceding claims, wherein the reflector is arranged so that the Weft thread as the sheet moves along the reflector and / or wherein the reflector is a retroreflective Reflector is. Method according to one of the preceding claims, wherein the measuring range (27) at a beginning, a End or in a gap of the warp threads arranged becomes. The method of claim 9, wherein the reflector when viewed in the direction of entry first or last leaf strut (2a) arranged outside the compartment is. Method according to one of the preceding Claims, wherein the duration of a signal from the Weft thread (4) in the measuring range (27) is generated, with a Target period is compared. Method according to one of the preceding Claims, wherein a signal amplitude of one of the weft (4) signal generated in the sensor (10) with a Target amplitude is compared Method according to one of the preceding Claims, wherein at the loom, a light source (15 ') is arranged stationary. Method according to one of the preceding Claims, wherein the light (17) from a light source (15, 15 ') and measured by a detector (19, 19') is, and wherein the light source (15, 15 ') and the detector (19, 19 ') together in a component (12, 22) are. Method according to one of the preceding Claims, wherein the weft thread (4) after the entry on both sides of the compartment is detected by terminals (3), and wherein he the measuring range (27) only after the detection reached or crossed by the terminals (3). Method according to one of the preceding Claims, wherein before an expected signal time a Reference measurement for determining a reference signal is performed, and wherein during the expected signal time a relative measurement to the reference signal is carried out. Method according to one of the preceding Claims, wherein the sensor has two parts (20, 22), one of which on an upper crossbar (24) and the second attached to a lower crossbar (22) of the sheet is, with the measuring range (27) between the Parts (20, 22) extends. Method according to one of the preceding Claims, wherein the weaving machine is a projectile weaving machine or a rapier loom.

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