EP0740639A1

EP0740639A1 - Process and device for detecting the winding of thread on a rotating roller

Info

Publication number: EP0740639A1
Application number: EP95940113A
Authority: EP
Inventors: Gerald Berger
Original assignee: Barmag AG; Barmag Barmer Maschinenfabrik AG
Current assignee: Oerlikon Barmag AG
Priority date: 1994-11-23
Filing date: 1995-11-22
Publication date: 1996-11-06
Anticipated expiration: 2015-11-22
Also published as: WO1996015969A1; CN1139412A; US5767963A; DE59503337D1; DE19543118A1; EP0740639B1; CN1069602C

Abstract

The invention relates to a process and device for detecting the winding (12) of a thread on a rotating roller (1) of a winding device about which the thread is partly wound, in which there are a light source (3, 4) to direct a beam of light (5) on the monitoring region of the roller (1) which is imaged along a surface line of the roller as a strip of light (50) and a light sensor (6, 8) with an evaluation device (10). The sensor detects the light reflected (13) from a thread winding which is converted into an electric signal and can then be processed further.

Description

Method and device for recognizing thread winding on a rotating roller

The invention relates to a method for detecting a thread winding on a rotating roller according to the preamble of claim 1 and a device for carrying out this method.

It is known to determine the bobbin diameter of a winding body, in particular a bobbin of a synthetic thread, by means of a pivoting sensing roller. For this purpose, the sensing roller lies on the winding body and rotates with it. If a thread malfunction occurs in the area of the sensing roller, the thread can be wound onto the sensing roller. Such an unwanted thread winding (= winder) leads to a malfunction. The malfunction can also lead to a malfunction in a traversing device upstream of the winding head and, in a short time, can cause considerable damage to the thread winding device due to the rapidly increasing volume of the thread winding on the sensing roller.

In order to keep the extent of the malfunction and damage as low as possible, it has already been proposed to provide a sensor plate arranged tangentially to the sensing roller. Since the sensing roller vibrates, it is necessary to provide an air gap between the sensing roller and the sensor plate. To ensure that no false alarms are triggered by the sensor plate under all operating conditions take place, the air gap must be made correspondingly large. This leads to the disadvantage that a noticeable thread winding must already have formed on the sensing roller so that the sensor plate triggers an alarm signal.

In view of this, the proposal has already been made to provide a light barrier which is arranged parallel to the sensing roller of the winding device. If a thread should now wrap around the feeler roller, the amount of light received is changed by the winder. If the value falls below a specified value (photo current), an alarm signal is triggered.

However, this solution does not take into account that the sensing roller vibrates. The vibrations of the feeler roller are caused by radial vibrations that result from inaccuracies in the roundness as well as from deflections or from pressure on the spools of thread. Such vibrations can also be caused by play in the bearing, unbalance and vibration transmission by the adjacent bobbins.

This solution therefore also does not provide satisfactory monitoring of the sensing roller or contact roller.

Finally, it is known from DE 26 28 994 AI, for monitoring selected length sections of a rotating contact roller or sensing roller with regard to thread windings from a light source arranged at a radial distance above the roller, a light beam at an angle between 0 ° and 90 ° to a monitoring area To align roller, capture the reflected light by a light-sensitive sensor and convert it into an electrical signal. Changes in intensity of the reflected light or of the scattered light caused by a winding are measured, evaluated and used to actuate a yarn cutting device. It is disadvantageous in the known method from which the invention is based that the monitoring area is essentially punctiform and the entire length of the roller of the winding device can only be monitored with great technical effort. However, this is necessary if, for example, a thread winder forms on an unsupervised section of the shaft when the traversing is stationary. It is possible to detect such thread winders by using a plurality of light sources and detector devices which are arranged along the roller or alternatively by moving the light source and the light-sensitive sensor device back and forth. As a result, however, the response time of the system is very high and the monitoring method is unsuitable for high winding speeds. In addition, if the roller surface is contaminated, the reflection properties deteriorate and a stable working point setting is made more difficult, as a result of which the functional reliability of the known device is severely restricted.

The present invention is therefore based on the object of specifying a method for the early detection of an unwanted winding at any location in the monitoring area of a rotating roller in a thread processing or thread winding device which works safely and reliably. Furthermore, a device is to be specified by means of which the detection of a winding thread on a roller of such a device can be carried out with a high level of functional reliability and a short reaction time.

This object is achieved for a method of the type defined in the preamble of claim 1 according to the invention by the features of the characterizing part of claim 1. Advantageous further developments are the subject of claims 2 to 10. A device according to the invention for detecting a winding thread on a roller Winding pre Direction is the subject of claim 11. Advantageous further developments of the device are the subject of claims 12 to 20.

The method according to the invention treads a new path for recognizing thread winding on a rotating roller, which is partly wrapped by the running thread. For this purpose, it is proposed to project a light bundle from a light source onto the roller at an angle of attack α to a surface line of the roller in such a way that it extends over the entire length of the monitoring region of the roller as a light band and the scattered light reflected by the thread spooling means to be detected by a sensor device and to trigger an alarm signal when at least one thread loop has been detected in the monitoring area of the roller. The position of the light sensor results from the claims.

The procedure is based on the following train of thought:

Due to a preferably substantially vertical arrangement of the evaluation device with respect to the monitoring area of the roller, radial vibrations of the roller have no influence on the detection of the thread. In this way, under certain circumstances a single thread wrap can already be ascertained on the roller. However, an arrangement of the light sensor is also possible in other areas. The measure of irradiating the roller with a grindingly incident, parallel or expanding light bundle offers in particular the advantage that the entire monitoring area, which lies between two at a distance from one another Normal planes of the roller is determined, is illuminated with a single light source and associated imaging optics when the angle of attack α to the surface of the roller is set correctly. This is dependent on the amplitude of the vibrations of the roller in winding operation, the manufacturing tolerances at the Manufacture of the roller and the height of any thrust rings on the roller. This angle of attack α is in the range between 3 ° and 10 °, preferably 5 ° and is determined in individual cases on the basis of the structural conditions by experiment. The detection of a winder is therefore carried out simultaneously in the entire monitoring area, whereas in the prior art only a selective detection was possible by successive measurements. The detection of the thread then takes place in that the thread, which consists of a plurality of filaments, reflects light and, as it were, flashes on the roller of the thread winding device. This flashing is recognized by the evaluation device as scattered light and a signal is then triggered. The irradiation of the scanning roller over the entire monitoring area with a grinding light beam ensures that the thread flashes even if there are one or a few turns, since the roller itself reflects only little light in the direction of the light sensor and therefore the incident scattered light is recognized as a deviation from a possibly existing basic radiation.

The light is preferably monochrome. The roller can e.g. B. be irradiated by means of a laser light source. Although this is not necessary, it offers the advantage of being able to design any necessary lens systems of the imaging optics more easily, since the monochrome light has a uniform wavelength and corrections to the lenses need only be taken into account for this uniform wavelength. Malfunctions due to external influences of daylight or ambient light can also be switched off more easily using filters. A laser light source is preferably an inexpensive way of providing a sharply delimited light bundle of monochrome light. Electronic laser light sources that operate in near-infrared wavelength ranges are preferred for the present invention. Known rollers of thread take-up devices have a plurality of raised thrust rings which are formed at an axial distance from one another, in order to set favorable speed conditions when changing the bobbin for thread threading or thread changing. In order to ensure that there are no unilluminated areas next to the thrust rings and that thread windings which arise in the "shadow" of the thrust rings are also detected, it is proposed according to claim 6 to irradiate the roller with two light sources arranged essentially opposite one another in one plane and with an axial distance, and thus to illuminate the entire surveillance area - also directly next to the thrust rings. This results in an arrangement of the sensor according to claim 6 and preferably according to claim 8.

It should be noted that the roller can be the thread delivery or thread take-off roller (godet) of a filament spinning machine. However, it is preferably the contact or feeler roller of a thread winding device in such a spinning machine for synthetic filament threads, the basic structure of which is known, for example, from US Pat. No. 5,029,762 A.

In order to detect thread winding on a rotating roller of a thread winding device, a device is proposed which has an optoelectric device (light sensor) which, in a preferred embodiment, is arranged essentially centrally above the monitoring area and at a distance on the side of the roller which is not is wound around the thread, and includes an evaluation device that triggers a signal. The optoelectric device is preferably electrically connected to the evaluation device.

The light reflected by a thread winding on the rotating roller is by the optoelectric device (Scattered light) is detected and converted into a preferably stationary electrical signal to be fed to the evaluation device, the evaluation device triggering a further signal when a tolerance limit is exceeded, which signal can be an alarm signal or a signal for thread cutting.

In particular, however, the device comprises a light source which is arranged outside the monitoring area and which directs a light beam in the longitudinal direction of the roller and at a small angle of attack to the roller. The light source preferably emits monochrome light, for example the light from a laser light source. For example, it can be a light beam that is rectangular in cross section or that is adapted to the monitoring area and expanded with suitable optics.

The optoelectric device preferably comprises imaging optics with a light sensor arranged behind a converging lens. The light sensor can be a CCD array or a photodiode.

The use of a sensor in the form of a CCD array has the advantage that it can be read out in accordance with the clock signal. By knowing the axial position of the thrust rings on a roller, in particular the sensing roller of a thread winding device, the measured values of the light sensor (interference reflections) from this area can easily be masked out using digital logic. The electronics enable a quick reaction to errors that can be in the range of milliseconds.

Further advantages and features of the method and the device are described using an exemplary embodiment. Show it :

1 shows a schematic arrangement of the sensing roller of a winding head with a device for winder monitoring;

FIG. 2 shows a modified device according to FIG. 1 with a different arrangement of the light sensor;

3 shows the light bundle reflected by the light source on a surface line of the roller and the light beam reflected by the roller in a radial plane of the roller.

On the shaft or roller 1, the z. B. has a diameter of 85 mm, several thrust rings 2 are formed. These come into contact with the bobbin tubes clamped on a chuck shaft (not shown) after a bobbin change.

The sensing roller 1 is irradiated by means of two light sources 3, 4 which are arranged at a distance from the sensing roller and are located opposite one another and lie in a radial plane. The angle of incidence α, at which the light or radiation beam 5 is incident on the scanning roller 1, is selected so sharply that each area of the side of the monitoring area of the roller 1 facing the optoelectrical device (light sensor) 6 - 8 is illuminated. The light sources 3, 4 emit a light beam 5 which is rectangular in cross section and has a width of approximately 10 mm and a depth of a few mm, preferably 1 mm. This is achieved, for example, with a collimator lens system, not shown, which comprises cylindrical lenses. The light bundle 5 is projected onto the roller in the monitoring area of the roller 1 as a line or as a very narrow light strip 50 running along a circumferential line in the circumferential direction of the roller. To cover the entire monitoring area 20 between two in the If the spaced normal planes of the roller 1 are formed to illuminate, the light sources 3, 4 are arranged laterally outside the monitoring area 20.

An opto-electric device (light sensor) 6-8 is arranged essentially perpendicular to the axis of rotation of the sensing roller 1 at a distance from the sensing roller 1, essentially centrally above the monitoring area 20 of the roller 1. The device comprises a converging lens 7, behind which a light sensor 8 is arranged. The light sensor 8 is constructed from photo diodes which convert the incident light into a photo current 15. A mask 9 is arranged in front of the light sensor 8 and hides the area of the thrust rings 2.

The light sensor 8 is electrically connected to an evaluation device 10 and this to an alarm display device 11.

Loops around a thread that z. B. runs at a speed of 8000 m / min, the sensing roller 1 and forms a winder 12, this reflects the light emitted by the light sources 3, 4. Furthermore, light rays of the light bundle 5 are diffracted on the fine capillaries of the filament threads. The reflected light 13 strikes the light sensor 8 through the collecting lens 7, which emits a signal 15 to the evaluation device 10, which is compared with a signal R which corresponds to a fault-free state. The evaluation device then triggers an alarm signal if a deviation occurs during a comparison that is greater than a permissible tolerance range.

By means of the present invention, the undesired winding of a thread on a sensing roller 1 over the entire length of the monitoring area 20 can be recognized at an early stage, especially after one or a few loops. so that a thread cut can be triggered before consequential damage to the dishwasher.

Very short response times can be achieved with photodiodes. Response times of one microsecond can be achieved. The actual response time depends on the amount of light reflected by the thread winder 12. Therefore, the angle of attack and the width of the light beam 5 directed towards the roller 1 should be kept as small as possible, for example 5 ° or less or narrower than 1 mm.

With a CCD sensor consisting of 1024 pixels and a clock frequency of 15 megahertz, a maximum response time of 70 microseconds can be expected.

The response times of both possible sensors are significantly less than 2 milliseconds. This reaction time is sufficient at winding speeds of 8000 m / min and with a feeler roller diameter of 85 mm to avoid consequential damage to the endangered components of the winding device.

Fig. 2 shows a modified device for winder monitoring according to Fig. 1. There, the image is taken from the perspective of the incident light beam 5, which from the light source 3 via an optical system, which encompasses the lenses 16, 17, to the here Probe roller 1, not shown, is projected. The reflected light 13 is deflected by the convex surface of the lens 17 and imaged on the opto-electrical evaluation device (light sensor) 7-8, which is arranged in the beam path of the reflected light beams 13, detects them and converts them into a photocurrent 15. As in FIG. 1, the latter is fed to the evaluation device 10 and compared there, for example, with a signal R, which detects the photocurrent 15 from the intensity of the reflected light of a scanning roller 1 without a thread. winding corresponds. The difference signal is then amplified in the evaluation device 10 and can actuate an alarm device 11 or the like if a predeterminable threshold value is exceeded.

The advantage of the arrangement according to FIG. 2 is that no components of the monitoring device have to be attached in the immediate vicinity of the sensing roller 1 to be monitored, so that the designer has greater freedom with regard to the accommodation, assembly and maintenance of the light source 3 (transmitter) and of the light sensor 7, 8 (receiving part) and the optics in between.

However, it should be pointed out that when there is a second light source - in order to illuminate the entire surveillance area and to prevent shadows from forming along with possible start-up rings - the two light sources 3, 4 should be arranged in parallel planes offset from one another by one avoid direct radiation of the light reflected on the surface of the feeler roller at the opposite light sensor.

3 finally shows in a schematic arrangement in a radial plane of the roller 1, which in the present case has no thrust rings, the position of the light source 3 with respect to the roller 1, for example, outside the monitoring area 20 of this roller. It also shows the assignment of the light sensor 6-8 for detecting the scattered light generated on a thread winding 12 possible in the monitoring area 20. This scattered light is created by reflection, diffraction and refraction of the incident light bundle 5 on the fine filament threads (capillary threads) of the thread winding, which are predominantly opaque. For an arrangement according to FIG. 3, the light sensor 6-8 can be arranged on the side of the roller 1 which is above the roller 1, ie above the tan potential plane of the roller 1, in which the light band 50 is located. Exceptions to this are the areas of the light beam 5 directed from the light source onto the roller 1 and the light beam 25 reflected from the roller 1, shown in hatched lines. The light sensor 6-8 can be arranged anywhere in an angularly offset plane. It only has to be ensured that the light sensor 6-8 measures the scattered light which arises on a thread or a winding of the thread and not the light beam reflected by the roller 1 itself and that clear differences in light intensity can be determined as a deviation of a photocurrent.

Claims

PATENT CLAIMS

1. Method for recognizing thread winding (12)

(= Winder) on a rotating roller (1) which is partially wrapped in a thread, in which the light bundle of a light source (3, 4) is directed onto a monitoring area of the roller (1) by the light source (3, 4) is arranged outside the monitoring area and is directed obliquely at the monitoring area, and in which the light reflected from the monitoring area is detected by a light sensor (6-8), and the light source (3, 4) and the light sensor ( 6-8) on the side of the roller (1) which is not wrapped in the thread, characterized. that the light beam (5) is directed onto the roller (1) in such a way that it forms a light band (50) on a surface line of the roller (1) and covers the monitoring area, and that the light sensor (6-8 ) is arranged outside of the light beam (3, 4) directed onto the monitoring area (20) and outside of the light beam (5) reflected by the roller (1).

2. The method according to claim 1, characterized in that the light band (50) has a width of less than 5 mm, preferably less than 2 mm.

3. The method according to claim 1 to 2, characterized. that the light beam (5) is directed at an angle of attack a between 3 and 8 °, preferably about 5 °, onto the roller (1).

4. The method according to claim 1 to 3, characterized in that the shaft (1) is irradiated with monochrome light.

5. The method according to claim 4, characterized in that the light beams (5) are the light of a laser light source.

6. The method according to claim 1 to 5, characterized in that the roller (1) by two Lichtcpielle (3, 4), which are opposite, each with a light beam (5) is irradiated such that on the roller (1) in excess ¬ surveillance area (20) an essentially common light band (50) is imaged, and that the light sensor

(6-8) outside of the light beams directed by the light sources (3, 4) onto the monitoring area (20) of the roller (1) and reflected by the roller (1)

(5) is arranged.

7. The method according to any one of claims 1 to 6, characterized in that the roller (1) is the sensing roller of a Fadenaufspulvorrich¬ device for synthetic continuous filaments.

8. The method according to claim 1 to 7, characterized in that the light sensor 6-8) for detecting the light from a thread winding (12) reflected light is arranged substantially centrally above the monitoring area of the roller (1).

9. Ver ears according to claim 1, characterized. that the light sensor (6-8) for detecting the light reflected by a thread winding (12) is arranged in the beam path parallel to the light source (3) emitting the light beams (5).

10. The method according to claim 9, characterized. that the light received by the light sensor (6-8) is detected as an electrical signal (15) and its change is amplified to trigger an alarm signal.

11. Device for detecting a thread winding (12) (winder) on a rotating roller (1) of a thread processing or thread winding device for carrying out the method according to claims 1 to 10, with a light source (3, 4) for irradiating the roller (1) in a monitoring area and a light sensor (6-8) for detecting the light reflected from the monitoring area, characterized in that the light source (3, 4) at such an angle of incidence a. is directed to the monitoring area (20) of the roller (1) that in the monitoring area a light band (50) is imaged on a surface line of the roller (1), which covers the length of the monitoring area, and that the light sensor (6-8) outside which is directed by the light source (3, 4) onto the monitoring area (20) of the roller (1) and is arranged outside the light bundle (5) reflected by the roller (1).

12. The apparatus according to claim 11, characterized in that the angle of attack (α) of the light source (3) to the axis of rotation of the roller (1) is between 3 and 10 °, in particular at 5 °.

13. The apparatus according to claim 11 or 12, characterized. that the roller (1) is irradiated by the light source (3) with monochrome light, which is preferably emitted by a laser light source.

14. The apparatus according to claim 11 to 13, characterized. that two light sources (3, 4) are directed at the monitoring area (20) of the roller (1) at such an angle of attack that an essentially common light band (50) is imaged in the monitoring area (20) of the roller (1), that covers the length of the monitoring area (20), and that the light sensor (6-8) outside the one directed by the two light sources (3, 4) in the monitoring area (20) onto the roller (1) and that of the roller (1) reflected light bundle (5) is arranged.

15. The apparatus according to claim 11 to 14, characterized. that the light sensor (6-8) has a collecting lens (7) arranged in the beam path of the light bundle (5) reflected by the thread winding (12).

16. The apparatus according to claim 11 to 15, characterized in that the light sensor (8) has a CCD array.

17. The apparatus according to claim 11 to 15, characterized in that the light sensor (8) has a photodiode.

18. The device according to at least one of claims 11 to 17, wherein the roller (1) has a plurality of axially spaced thrust rings (2), characterized in that in the beam path between the converging lens (7) and

Light sensor (8) a mask (9) is arranged.

19. Device according to one of claims 11 to 18, characterized. that the roller (1) is the sensing roller (1) of a thread winding device or a thread conveying godet of a spinning machine for synthetic threads.

20. The apparatus according to claim 11, characterized in that the light sensor (6-8) is arranged in a plane which is parallel to the plane in which the light source (3) lies, which the light beam (5) on the roller ( 1) judges.