WO2014012189A1

WO2014012189A1 - Photoelectric monitoring of a rotational yarn movement

Info

Publication number: WO2014012189A1
Application number: PCT/CH2013/000126
Authority: WO
Inventors: Xin Xu; Bo Su; Zhonghua CAO; Yazhou Liu
Original assignee: Uster Technologies Ag
Priority date: 2012-07-19
Filing date: 2013-07-12
Publication date: 2014-01-23
Also published as: CN103572440A

Abstract

The present invention discloses a device (1) for photoelectrical monitoring the rotational movement of a yam (13) in a ring-spinning unit (10). The device is mounted above a spindle (16) of the ring- spinning unit. It comprises a housing (26) and a yam guide (14) for guiding the yam (13). A light emitter (21) is mounted within the housing (26) and is adapted to emit a beam of light (25) toward the yam (13). A light receiver (22) is mounted within the housing (26). The light emitter (21) and the light receiver (22) are mounted in juxtaposition with each other, and the light receiver (22) is adapted to receive light emitted by the light emitter (21) and reflected by the yam (13). The invention offers the advantages of small size, low cost, easy installation, easy replacement and immunity to electromagnetic- interference.

Description

PHOTOELECTRIC MONITORING OF A ROTATIONAL YARN MOVEMENT

TECHNICAL FIELD

The present invention lies in the field of ring spinning and relates to a device and a method for photoelectrically monitoring a rotational movement of a yarn in a ring-spinning unit, according to the preambles of the independent claims.

PRIOR ART

A ring-spinning unit in a ring-spinning frame spins in the following basic way: the roving is drafted by means of (in most cases) three pairs of draft rollers to form a yarn, which is then wound onto a bobbin through a yarn guide arranged between the draft rollers and the bobbin. In order to wind the yam around the bobbin, the yam is guided by means of a traveler rotating on a ring rail. When the bobbin is driven to rotate, the traveler also rotates with the yam, however, with a rotational speed lower than that of the bobbin. Thus, the yam is passively wound around the bobbin and is simultaneously twisted around its own axis. In the spinning process, it is very important to detect the two phenomena of slipper spindle and broken yarn. The expression 'slipper spindle' means that the actual rotational speed of the spindle is slower than the set rotational speed. The expression 'broken yam' denotes a breakage of the yam due to its own or external causes. There are mainly three conventional methods for detecting slipper spindle and broken yam.

The first method, described in US-2,930,179 A, makes an electromagnetic sensor move back and forth on a long rail beside the ring plate, and thus detects the travelers of spinning units on a series of spinning frames. The movement speed of the sensor is much lower than the rotational speed of the travelers. When the sensor passes near a certain spindle, the magnetic- field intensity may be changed periodically with the rotation of the traveler, and thus a periodic electric signal is obtained for detecting the spinning state. This method has the disadvantages that its costs are high, the corresponding apparatus is not easy to be installed but easy to be damaged, it has a low signal-to-noise ratio, and is not applicable to a variety of spinning frames, especially when the traveler is made of a non-ferromagnetic material.

The second detection method, described in DE-37'08' 1 14 Al , detects the traveler by making use of a photoelectric sensor, which solves the problem with different materials of the traveler. However, it likewise has some disadvantages for some spinning frames; for instance the installation can be difficult or impossible, or an operator is hindered from working by the installation. According to the third method, described in EP-0'480'898 Al , a light emitter and a light detector are mounted above the spindle and aligned to each other so as to fonn a light barrier. The rotating yarn periodically interrupts the light beam emitted by the light emitter, which is detected by the light detector.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a further device and method for monitoring the rotational movement of a yarn in a ring-spinning unit, and thus detect the two phenomena of broken yarn and slipper spindle. The device shall have a small size, low manufacturing costs and shall be easy to install, maintain and replace. The detection method shall be better adapted to the actual needs.

These and other problems are solved by the device and method defined in the independent claims. Preferred embodiments are defined in the dependent claims.

The invention is based on the idea of optically monitoring the rotational yarn movement above the spindle of a ring-spinning unit by detecting light reflected or scattered from the yarn. Light is emitted toward the yarn rotating in a region between a yarn guide and the spindle, reflected or scattered by the yam, received and converted into an electric signal. The electric signal will be generally periodic, with a period which corresponds to one rotation period of the yam. The rotational speed of the traveler is obtained indirectly according to the period of the obtained signal. If the rotational speed is not within a predetermined range, the ring-spinning unit is not working properly, and an alarm can be given.

The device according to the invention is for photoelectrically monitorin the rotational movement of a yarn in a ring-spinning unit. The device is adapted for being mounted above a spindle of the ring-spinning unit. It comprises a housing, a yarn guide for guiding the yarn, a light emitter mounted within the housing below the yam guide and adapted to emit a beam of light toward the yam, and a light receiver mounted within the housing below the yam guide. The light emitter and the light receiver are mounted in juxtaposition with each other. The light receiver is adapted to receive light emitted by the light emitter and reflected by the yam.

The term 'in juxtaposition with each other' as used in the present document means that the light emitter and the light receiver are close to each other. Certain spacing between them is allowed, but their mutual distance should not be larger than about 10 mm.

For the sake of simplicity, terms such as 'reflect^" or 'reflexion' are understood in this document to designate both optical phenomena of reflexion and backward scattering of light.

The light emitter and the light receiver can be both mounted on one common circuit board.

The light emitter and the light receiver are preferably mutually isolated by an opaque separating wall which prevents light emitted by the light emitter from directly impinging on the light receiver. The light emitter is, for instance, a light-emitting diode (LED).

In one embodiment, the device comprises one single light emitter which emits light in the at least two different wavelength bands. Such a light emitter can be a multicolor light-emitting diode which emits light in the at least two different wavelength bands, as known from the prior art (e.g., US-7,333,203 B2). In another embodiment, the device comprises at least two light emitters which emit light in at least two different wavelength bands. The use of at least two different wavelength bands has the advantage of a more reliable detection of all kinds of yams, which may have various colors. One of the at least two di ferent wavelength bands preferably lies in the visible spectral range and another one of the at least two different wavelength bands preferably lies in the in rared spectral range. The use of infrared light is advantageous especially for the detection of dark yarns, which hardly reflect visible light, but may reflect in rared light.

The light receiver can be, e.g., a photocell, a photoresistor, a photodiode, or a phototransistor.

The device can additionally comprise a microcontroller unit as a means for providing power supply, signal processing and/or communication for the device.

The device can additionally comprise an indicator for indicating whether the detected rotational movement of the yarn corresponds to a predefined specification or not.

In one embodiment, the device comprises a hinge for swinging up at least a part of the device including the yarn guide for better accessing the spindle.

The invention also relates to a ring-spinning unit comprising a spindle, a ring having the same axis as the spindle, a traveler movably arranged on the ring, and a device for photoelectrically monitoring the rotational movement of a yarn in the ring-spinning unit, the device being mounted above the spindle. The device for photoelectrically monitoring the rotational movement of a yam is the device described above.

Furthermore, the invention relates to a method for photoelectrically monitoring the rotational movement of a yam in a ring-spinning unit above a spindle of the ring-spinning unit. Yarn is guided by a yarn guide mounted above the spindle. A beam of light is emitted toward the yarn so as to hit the yam in a region between the yam guide and the spindle. At least part of the beam of light hits the yarn, is reflected by the yam and is received. An electric signal being a measure for the received light is generated. it can be advantageous to emit light in at least two different wavelength bands. One of the at least two different wavelength bands preferably lies in the visible spectral range and another one of the at least two different wavelength bands preferably lies in the infrared spectral range. The operating light wavelengths of the light emitter and receiver should match each other. The term 'light' encompasses in the present document not only the visible (VIS) range of the electromagnetic spectrum, but also the adjacent ranges, i.e., the infrared (IR) and the ultraviolet (UV) ranges. The light used should be distinguishable from the background radiation. Measures for achieving this purpose, such as the use of an optical filter in front of the light receiver, are known to the person skilled in the art.

The present invention provides a device for photoelectrically monitoring the rotational movement of a yarn in a ring-spinning unit and thus for detecting the undesired phenomena of broken yarn and slipper spindle. The invention offers the advantages of small size, low cost, easy installation, easy replacement and immunity to electromagnetic-interference. It is less sensitive to changes of the operating distance than the electromagnetic sensor known from the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described in the following with reference to the drawings, which are for the purpose of illustrating the preferred embodiments of the invention and not for the purpose of limiting the same.

Figure 1 is a schematic side view of a spinning unit of a ring-spinning unit with a device according to the invention.

Figure 2 is a schematic top view of a photoelectric sensor for the device according to the invention.

Figure 3 shows an example of an electric signal outputted by the photoelectric sensor of

Figure 2.

Figure 4 shows a cross section through another embodiment of the device according to the invention.

Figure 5 shows an arrangement of multiple devices according to the invention on a ring- spinning frame. DESCRIPTION OF PREFERRED EMBODIMENTS

In the ring-spinning unit 10 schematically shown in Figure 1. roving 12 is drafted by means of several pairs of draft rollers 1 1 having different rotational speeds, the downstream rollers having a higher speed than the upstream rollers. Thus, a yarn 13 is formed. The yarn 13, after passing through a yam guide 14, is wound around a bobbin 17. The bobbin 17 is driven to rotate by a spindle 16. Typical rotational speeds (or frequencies) of a spindle 16 are between 10^'OOO and 25Ό00 rpm, i.e., 43 to 167 Hz. A traveler 18 is movably arranged on a ring 19 having the same axis as the spindle 16. The yam 13 is guided by the traveler 18, such that the traveler 18 rotates on the ring. The rotational speed of the trav eler 18 is lower than that of the spindle 16. Thus, the yam 13 is twisted around its own axis, in addition to being wound around the bobbin 17. A balloon controller 15 limits the rotational amplitude of the yam 13. When the spindle 16 is driven to rotate, the balloon controller 15 and the ring 19

synchronously move slowly up and down, such that the yam is wound along the whole length of the bobbin 17. In Figure 1 , the yam has been wound onto the lower half of the bobbin 17; when the yam 13 is wound onto the upper half of the bobbin 17, the balloon controller 15 is closer to the yam guide 14. When the bobbin 17 is nearly full with the yam 13, the balloon controller 15 is close to the yam guide 14. The yam guide 14, e.g., a pigtail yam guide, is located between the draft rollers 1 1 and the bobbin 17, and thus between the draft rollers 11 and the spindle 16.

A device 1 according to the invention is mounted above the spindle 16. The device 1 comprises a reflective photoelectric sensor 20 mounted such that it aims at the rotational orbit of the yarn 13. A light emitter in the sensor 20 emits lights toward the yam 13. Part of the light is reflected by the yam 13 and received by a light receiver in the sensor 20.

Figure 2 is a top view of the reflective photoelectric sensor 20. A light emitter 21 , e.g., a light-emitting diode (LED), emits a light beam 25 toward the yam orbit 130, which is represented in Figure 2 by a dotted circle in the drawing. At least part of the light 25 emitted by the light emitter 21 is reflected by the yam 13, and at least part of the reflected light is received by the light receiver 22. e.g., a phototransistor. The light receiver 22 generates an electric output signal which is a measure for the light intensity received. Thus, the output signal is essentially periodic, and its period corresponds to that of the rotational movement of the yarn 13. The light receiver 22 can be any photosensitive element, such as a photocell, a photoresistor, a photodiode, or a phototransistor. However, using a phototransistor as the light receiver 22 may make the subsequent circuit processing simpler because of its high photocurrent.

The light emitter 21 and the light receiver 22 are mounted in juxtaposition with each other, i.e., close to each other, on a circuit board 24. On the circuit board 24 can be provided a microcontroller 23 as a means for providing power supply, signal processing and/or communication for the device 1, in particular for the light emitter 21 and the light receiver 22. In the embodiment of Figure 2, the light emitter 21 and the light receiver 22 are airanged side by side in a horizontal plane; alternatively, they can be airanged about each other in a vertical plane (see Figure 4) or in any other arrangement.

In one embodiment, the light emitter 21 emits light 25 in at least two different wavelength bands. One of the wavelength bands may lie in the infrared spectral range, in order to obtain a reflection signal from such yams 3 that have only a low reflectivity in the visible spectral range, i.e., 'dark' yams. A multicolor light-emitting diode can be used as a light emitter 21 which emits the light in the at least two different wavelength bands. Alternatively or additionally, the sensor 20 can be equipped with at least two light emitters which emit light in distinct wavelength bands.

The sensor 20 is connected to a central control and evaluation device (not drawn) via a data input/output line 28. A power line 29 supplies the sensor 20 with electric power. The sensor 20 has a housing 26. At least a part of a front surface of the housing 26, i.e. of the surface facing the yam 13, should be transparent for the light emitted by the light emitter 21.

Preferably at least one transparent window 27, through which the light 25 passes from the light emitter 21 toward the yam 13 and from the yarn 13 toward the light receiver 22, is provided in the front surface. An example of an electric output signal U(t) of the light receiver 22, e.g., a time-dependent voltage, is shown in Figure 3., The signal U(t) is periodic with a period T. Each period T has two peaks, since the yarn 13 passes twice through the light beam 25 in each rotation.

However, the sizes of the two peaks are not equal due to the different distances of the yarn 13 from the sensor 20 in the two intersection points; the intersection point closer to the sensor 20 produces a higher peak. Therefore, the two peaks can be well distinguished from each other, and the period T can be determined from the signal U(t). Since one period T corresponds to one rotation of the yarn 13, the rotational frequency f of the yarn 13 is 1/T. The rotational frequency of the traveler 18 is the same as that of the yarn 13, because the yarn 13 is guided by the traveler 18. Thus, by evaluating the output signal U(t) such as shown in Figure 3, it is possible to determine the rotational frequency f of the yarn 13 and the traveler 18. A person skilled in the art knows how to evaluate the output signal U(t) and determine its frequency f. using analog and/or digital evaluation means.3

Figure 4 shows a cross section through another embodiment of a device 1 according to the invention. Elements corresponding to those introduced above are designated with the same reference numerals. The yarn guide 14 is mounted in the housing 26 and protrudes from its front end. In the embodiment of Figure 4, the light emitter 21 and the light receiver 22 are embedded vertically about each other in the housing 26. The light emitter 21 and the light receiver 22 directly emerge from the housing 26, rather than being covered by a window 27 (as in Figure 2). They are mutually isolated by an opaque separating wall 41 which prevents light 25 emitted by the light emitter 21 from directly impinging on the light receiver 22. The housing 26 can also accommodate a circuit board 24 (not shown in Figure 4) as described with reference to Figure 2.

An indicator 42. e.g., a light-emitting diode (LED), is mounted in the housing 26 such that in the operating state it can be seen from outside by an operator. The indicator 42 indicates whether the corresponding spinning unit 10 is working properly or not, i.e., whether the detected rotational movement of the yarn 13 corresponds to a predefined specification or not. Thus, the operator will quickly recognize a spinnin unit 10 with a broken yam or a slipper spindle, and may take the necessary countenneasures. The various states of the spinning unit 10 can be indicated by the indicator 42 not emitting any light at all, emitting light

continuously, blinking, emitting different colors, etc. Alternatively, the light 25 emitted by the light emitter 21 can be used for the indication purposes described above. It can, for instance, emit a warning signal by emitting blinking light 25. In other words, the light 25 is switched on and off with a frequency easily recognizable by a human eye, e.g., between 1 and 10 Hz. Alternatively or additionally, the warning signal emitted by the light emitter 21 can use light of a color different from the color used for the detection. If, for example, green light is used for the detection, red light may be used for the warning signal.

The housing 26 is pivotably mounted on a support 43 via a hinge 44, such that the housing 26 and the yarn guide 14 can be swung up for better accessing the spindle 16 (see Figure 1). The support 43 is provided with an opening 45 for mounting the device 1 on a spinning frame; cf. Figure 5.

The support 43 also bears an electronic housing 46. The electronic housing 46 accommodates electronic components 47. The electronic components 47 are preferably mounted on one or several printed circuit boards (PCBs) 48. The electronic components 47 can comprise, e.g., the microcontroller 23 described with reference to Figure 2 and/or a multiplexer for multiplexing signals of a plurality of devices 1 according to the invention, as shown in Figure 5. The electronic housing 46 can also accommodate electric cables for energy and/or signal transmission, such as the lines 28, 29 described with reference to Figure 2. An electric connection between the electronic components in the housing 26 and the electronic housing 46 can be established by one or several wires (not shown).

Figure 5 shows a plurality of devices 1 according to the invention equidistantly mounted on a rod 51. Such an equidistant arrangement of devices 1 is for a ring-spinning frame, where one device 1 is assigned to each spinning unit 10. A modern ring-spinning frame has actually a large number of spinning units 10, typically many hundreds.

The above introduction only roughly describes the basic working principle of the sensor. The present invention is not limited to the embodiments discussed above. The above description of the embodiments aims to describe and illustrate the technical solution related to the present invention. The obvious transformation or substitution based on the inspiration of the present invention should also be regarded as within the scope of protection of the present invention. The above embodiments are used to illustrate the most preferred embodiments of the present invention, so that those of ordinary skill in the art can apply the various embodiments and alternative means of the present invention to achieve the purpose of the present invention. LIST OF REFERENCE SIGNS

1 Device

10 Spinning unit

1 1 Draft roller

12 Roving

13 Yam

130 Yam movement orbit

14 Yarn guide

15 Balloon controller

16 Spindle

17 Bobbin

18 Traveller

19 Ring

20 Reflective photoelectric sensor

21 Light emitter

22 Light receiver

23 Microcontroller

24 Circuit board

25 Light beam

26 Housing

27 Window

28 Data input/output line

29 Power line

41 Separating wall

42 Indicator

43 Support

44 Hinge

45 Opening in the support

46 Electronic housing

47 Electronic components

48 Printed circuit board

51 Rod

Claims

IMS

A device (1 ) for photoelectncally monitoring the rotational movement of a yarn (13) in a ring-spinning unit (10), the device being adapted for being mounted above a spindle (16) of the ring-spinning unit (10) and comprising

a housing (26),

a yam guide (14) for guiding the yam (13),

a light emitter (21) mounted within the housing (26) below the yarn guide (14) and adapted to emit a beam of light (25) toward the yam (13), and

a light receiver (22) mounted within the housing (26) below the yam guide (14), characterized in that

the light emitter (21 ) and the light receiver (22) are mounted in juxtaposition with each other, and

the light receiver (22) is adapted to receive light emitted by the light emitter (21) and reflected by the yam (13).

The device (1 ) according to any of the preceding claims, wherein the light emitter (21) and the light receiver (22) are both mounted on one common circuit board (24).

The device (1) according to any of the preceding claims, wherein the light emitter (21) and the light receiver (22) are mutually isolated by an opaque separating wall (41) which prevents light (25) emitted by the light emitter (21 ) from directly impinging on the light receiver (22).

The device (1 ) according to any of the preceding claims, wherein the light emitter (21 ) is a light-emitting diode.

The device (1) according to any of the preceding claims, comprising one single light emitter (21) which emits light (25) in the at least two different wavelength bands.

6. The device (1) according to claims 4 and 5, wherein the light emitter (21 ) is a

multicolor light-emitting diode which emits light (25) in the at least two different wavelength bands.

7. The device (1 ) according to any of the preceding claims, comprising at least two light emitters which emit light (25) in at least two different wavelength bands. 8. The device (1) according to any of the claim 5-7, wherein one of the at least two different wavelength bands lies in the visible spectral range and another one of the at least two different wavelength bands lies in the infrared spectral range.

9. The device (1 ) according to any of the preceding claims, wherein the light receiver (22) is a photocell, a photoresistor, a photodiode, or a phototransistor.

10. The device (1 ) according to any of the preceding claims, additionally comprising a microcontroller unit (23) as a means for providing power supply, signal processing and/or communication for the device ( 1 ).

1 1. The device (1) according to any of the preceding claims, additionally comprising an indicator (41 ) for indicating whether the detected rotational movement of the yarn (13) corresponds to a predefined specification or not. 12. The device (1 ) according to any of the preceding claims, comprising a hinge (44) for swinging up at least a part of the device ( 1 ) including the yarn guide ( 14) for better accessing the spindle (16).

13. A ring- spinning unit (10), compri sing

a spindle (16),

a ring ( 19) having the same axis as the spindle (16),

a traveler ( 18) movably arranged on the ring ( 19), and

a device for photoelectrically monitoring the rotational movement of a yarn (13) in the ring-spinning unit, the device being mounted above the spindle (16),

characterized in that

the device for photoelectrically monitoring the rotational movement of a yarn (13) is a device (1 ) according to any of the preceding claims. A method for photoelectrically monitoring the rotational movement of a yarn (13) in a ring-spinning unit (10) above a spindle (16) of t he ring-spinning unit (10), wherein yam is guided by a yam guide (14) mounted above the spindle (16), and

a beam of light (25) is emitted toward the yarn (13) so as to hit the yarn (13) in a region between the yarn guide (14) and the spindle (16),

characterized in that

at least part of the beam of light (25) hits the yam (13), is reflected by the yam (13) and is received, and

an electric signal being a measure for the received light is generated.

The method according to claim 14, wherein light (25) in at least two different wavelength bands is emitted.

16. The method according to claim 15, wherein one of the at least two different

wavelength bands lies in the visible spectral range and another one of the at least two different wavelength bands lies in the infrared spectral range.