WO2008154756A9 - Device and method for testing moving textile materials - Google Patents

Abstract

The device serves for the testing of a moving textile material (4). An optical component (10) surface (100) which faces the textile material (4) has a structure with raised areas (101) and/or recesses (102) which counteracts the contamination of the surface (100). The raised areas (101) can, for example, catch particles of contamination (41) flying toward the surface and as such prevent the contamination of other zones (104) lying in the slipstream thereof. In this way, the contamination susceptibility of the surface (100) is reduced, which leads to a more reliable testing of the textile.

Description

 DEVICE AND METHOD FOR TESTING MOVEMENTS

TEXTILE MATERIALS

AREA OF EXPERTISE

The present invention is in the field of textile material testing. It relates to a device and a method for testing a moving textile material, according to the preambles of the independent claims. The invention can be used, for example, in optical yarn cleaners on spinning or winding machines.

STATE OF THE ART

There are a variety of different devices for testing textile materials known. After their application they can be divided into the two classes laboratory testing (offline) and testing during the production process (online). In Textilprüfvorrichtungen different sensor principles are used; The use of a specific sensor principle depends, among other things, on which property should be optimally detected. Frequently used sensor principles, especially the yarn test, are the capacitive and the optical. In the latter, the yarn is illuminated by a light source, and light interacting with the yarn is detected by a light detector. From this, for example, the yarn thickness or the presence of foreign substances can be determined. WO 93/13407 A1 gives an example of an optical yarn cleaner.

When working on textile materials, eg. B. when spinning or rewinding of yarn, fall considerable amounts of dust particles, fiber fragments, and Avivage- dirt particles. These particles - hereinafter referred to simply as "dirt particles" or "dirt" - float in the air and deposit on the surfaces of the components of textile machinery. The release of such dirt particles is promoted by friction between the running textile material and machine parts in contact with it. The components of the Textile testers are particularly close to the running fabric and are covered with such deposits after a relatively short time. As a result, the surfaces soon reach a degree of contamination that impairs the functioning of the sensors or even makes them impossible. This makes the textile test unreliable. In order to compensate for the contamination, parameters used during the evaluation, such as yarn cleaning limits, would have to be continuously adapted to the degree of soiling.

The contamination problem has a particularly strong effect on optical textile testing devices, because even a slight contamination of the optical

Surface can strongly influence the light used for detection by means of absorption and / or scattering. An "optical surface" is understood here to mean a surface of an optical component which interacts with the light used, that is, for example, the light is transmitted or reflected.

Of course, the optical surfaces can be cleaned periodically as part of preventive maintenance. For this purpose, US Pat. No. 5,163,201 A discloses a method and a device for cleaning the measuring space of a probe head of a thread monitoring device. The cleaning process is carried out when there is no yarn in the probe. The cleaning device includes a brush whose cleaning activity can be further assisted by a blowing nozzle for blowing clean air and a suction nozzle for dirt extraction. However, the cleaning operations have business interruptions and lead to a poor efficiency of the textile machine. In addition, the optical surfaces are increasingly scratched by the numerous cleaning processes, whereby the light transmission is permanently reduced ("blindness" of the optics.) Too severely scratched optical components must be replaced and have a correspondingly low life, resulting in replacement costs and leads to a further reduction the degree of utilization of the textile machine.

The CH-597'079 A5 proposes to design an optical thread monitor so that the thread makes contact with a light-transmitting cover of the light transmitter and the light receiver. The thread makes a circular motion during the spinning process and slides so over the cover that he frees them from the dirt. The friction between thread and cover leads to a scratching of the surface of the cover, in particular by the action of the harder dirt components after a relatively short time, which leads to the disadvantages described above.

According to WO-93/12028 Al, a yarn monitoring device is arranged in the traversing region of the yarn. The device has a U-shaped measuring gap with two opposite the yarn run inclined sensor surfaces. It works on itself contactless, but at the reversal points of the Fadenchangierang each yarn touched briefly one of the two sensor surfaces, whereby the sensor surfaces are cleaned. Also, the sensor surfaces of this device are scratched over time.

WO-00/07921 A1 describes a measuring device for yarn. The device has a thin measuring gap through which the yarn moves along its longitudinal direction. On both sides of the measurement gap, lying opposite each other, are

Measuring elements for measuring yarn properties attached. The measuring elements may be electrodes of a capacitive measuring system or window of an optical measuring system. The walls of the measuring gap including the measuring elements are covered with an abrasion-resistant coating, for example a nanocomposite or a sol. This increases the service life of the measuring gap. The self-cleaning of the measuring gap is better exploited by the narrowing of the measuring gap can be made so that the yarn touches the walls of the measuring gap and transported away dirt deposits, without damaging the measuring gap. However, even such a coating is subject to wear over time.

EP-1'035'059 A2 discloses a device for optical yarn monitoring. The surfaces of the optical components are provided with a translucent coating, which reduces the deposition of dirt deposits and reduces the wear of the surface due to mechanical action. Suitable materials for such a coating include a ceramic material and ^Teflon® . However, the application of such coatings to optical surfaces is technically complicated and expensive. According to DE-74'35'828 U, protective glasses or protective films are arranged in an optical diameter measuring device between the measuring object and the measuring optics. These can be easily cleaned or replaced. They can also be passed continuously or intermittently past the measuring optics, so that contamination can not exert a disturbing effect over a relatively long period of time because there is always a new section of the protective glass or the protective film between the object to be measured and the measuring optics. The protective glasses or protective films can also be assigned a cleaning bath. However, this optical diameter meter has a considerable footprint and requires a lot of effort for the mechanical devices and the implementation of the cleaning functions, which leads to high costs.

It is known to make outer surfaces, in particular of measuring devices, dirt-repellent or self-cleaning by means of a suitable texture. Examples of this can be found in the publications WO-96/04123 Al, EP-1,055,924 A2, WO-00/58410 Al or WO-02/14804 Al. These phenomena are summarized under the name "lotus effect" ^® The low wettability is achieved by a special structure of the surface (ie texture) The surface has elevations and depressions, the distance between the elevations and the height of the elevations in the Such a texture minimizes the adhesion forces between the surface and a liquid contacting it so that it does not wet the surface, and the effect of the texture can be further enhanced by making the surface of wetting-repellent material.

The prior art also includes nanotextured surfaces. A nanotextured surface has a texture whose typical structure sizes are in the nanometer range, ie from about 1 to 100 nm. An overview of nanotechnology and nanostructuring can be found, for example: For example, the "scientia halensis - Scientific Journal of the Martin-Luther-University Halle-Wittenberg", issue 2/2004. PRESENTATION OF THE INVENTION

It is an object of the present invention to provide an apparatus and method for testing moving textile materials which avoids the above-mentioned disadvantages of the prior art. The textile test should be less affected by dirt deposits and thus more reliable. In particular, the tendency to fouling is to be reduced by essential for the measurement surfaces of the inventive device and a gentle cleaning of the surfaces are facilitated.

These and other objects are achieved by the device according to the invention and the method according to the invention, as defined in the independent patent claims. Advantageous embodiments are specified in the dependent claims.

The invention is based on the recognition that a suitable texture of the surfaces of components can counteract contamination thereof. "Texture" in this document refers to the structural nature of a surface.The textured surface always includes height variations, ie elevations and / or depressions, the height of which, however, is always very small in comparison to the longitudinal and transverse dimensions of the surface. Whether such height variations are perceived as elevations from the surface plane, as depressions in the surface plane or as adjacent elevations and depressions is often a question of intuition and should play no role in the following description of the invention.

The device according to the invention for testing a moving textile material includes a passage region through which the textile material is movable, and a component which has a surface facing the textile material. The surface has a texture with elevations and / or depressions, which counteracts contamination of the surface.

In the method according to the invention for testing a moving textile material, the textile material is attached to a component which is a surface facing the textile material has moved past. The surface is provided with a texture with elevations and / or depressions, which counteracts contamination of the surface.

A first preferred embodiment of the device according to the invention is based on a "slipstream effect." If the textile material to be tested is always guided past the component in the same direction, the dirt deposit always takes place from the same direction Intercept incoming dirt particles and prevent soiling of other, lying in the lee of the surveys zones of the surface.Thus, the surveys act as "shields", which specifically capture dirt and keep other areas of dirt free.

A second preferred embodiment of the device according to the invention is based on the "lotus effect" ^® The lotus effect ^® is understood to mean the low wettability of a surface, which is achieved by a special structure of the surface (ie texture) Wells, wherein the distance between the elevations in the range of 1 nm to lmm, preferably from 0.1 to 200 microns, and the height of the elevations in the range of 1 nm to 1 mm, preferably from 0.1 to 100 microns, is located.

The surface texture can be based on nanotechnology. A nanotextured surface has a texture whose typical structure sizes are in the nanometer range, ie from about 1 to 100 nm. In addition, the nanoparticles should be aligned as subunits in a functional system. The nanotextured surface can, for. Example, a very thin functional layer and / or contain particularly small particles or be structured in the range of nanometers.

The invention has a variety of applications in textile material testing. It can be used in laboratory testing (offline) or during testing during the production process (online). It is suitable for various measuring principles such. As the optical or the capacitive measuring principle, with their advantages come in the extremely polluting optical measuring principle to best advantage. TITLE OF DRAWINGS

The invention will be explained in detail with reference to the schematic drawings. Figure 1 shows in a perspective view an optical yarn cleaner, as it is known from WO-93/13407 Al. FIG. 2 shows in a perspective view a textured surface as it can be used in the device according to the invention. FIG. 3 shows a perspective detailed view of a region of the textured surface which is designated III in FIG.

FIG. 4 shows a side view of a region of the textured surface which is shown in FIG

FIG. 3 is designated by IY. Figure 5 shows another erfmdungsgemässe execution form a textured

Surface in an analogous to Figure 3 representation.

The following description refers to the embodiment of an optical yarn cleaner. This example should by no means be understood as limiting. The invention is suitable both for other applications, for example for the testing of textile webs, as well as for other measuring principles, for example. For the capacitive measuring principle.

EMBODIMENT OF THE INVENTION

FIG. 1 shows an example of an optical yarn cleaner 1 in a perspective view

View shown. Such a yarn cleaner 1 is described in WO-93/13407 Al. The yarn cleaner 1 has a housing 2 which has a measuring gap 3 for the passage of a yarn 4 or another thread-like structure. The yarn 4 is moved along its longitudinal direction, which is indicated by an arrow 40, and is guided by not shown guide means so that it can not escape substantially transversely to its longitudinal direction. In a source part 5 of the housing 2 is a light source 7, for example, a light emitting diode (LED). A first light feeder 8 splits light from the light source 7 into two bundles and throws it over two entrance prisms 9, 9 '. The yarn 4 reflects the light reflected by an exit surface 100 into a first exit prism 10 and is fed via the first exit prism 10 and a second light feeder 12 to a first light sensor 14. The terms "entry" and "exit" refer to the yarn 4. In a sensor part 6 of the housing 2, there is a second exit prism 11 and a third light supply 13, which supply the light transmitted through the yarn 4 to a second light sensor 15. The measuring gap 3 is located between the source part 5 and the sensor part 6 of the housing 2. The light feeders 8, 12, 13 act as light guides and are z. B. as injection molded parts made of a translucent for the light plastic or as internally mirrored cavities.

In optical textile inspection devices, the above-described problem of contamination of optical surfaces is observed. In the example of FIG. 1, the optical surfaces, which are located in the measuring gap 3 and face the yarn 4, are particularly affected by the contamination, that is to say they are in the same way as in FIG. H. the entry surfaces of the entrance prisms 9, 9 'and the exit surfaces of the exit prisms 10, 11. Hereinafter solutions of the pollution problem according to the invention will be described with reference to FIGS 2-5.

FIG. 2 shows, in a very schematic perspective illustration, a surface 100 in a device 1 according to the invention, for example the optical exit surface of the first exit prism 10 in the optical device 1 of FIG. 1. The surface 100 which faces the yarn 4 and is therefore particularly susceptible to contamination , has a texture. The texture is designed and oriented to reduce or prevent contamination of at least portions of the surface 100. The texture may cover the entire surface 100 or only part or all of it.

An embodiment of the texture of the surface 100 is shown in FIG. The texture in this example consists of a substantially one-dimensional grid. In the transverse direction y, the grating is invariable. In the longitudinal direction x, the grid is periodic and is composed alternately of wedge-shaped or sawtooth-shaped elements 101 and flat elements 102 together. The wedge-shaped elements 101 protrude as elevations from the surface plane xy, in which the flat elements 102 lie out. The grating period p can be between 1 μm and 1 mm, for example between 5 μm and 50 μm around xind preferably about 10 microns. The wedge-shaped elements 101 and the flat elements 102 may, but need not, have the same extent in the longitudinal direction x. The wedge angle α can be between 10 ° and 80 °, for example between 15 ° and 45 ° and preferably about 30 °. This results in typical wedge heights h between approximately 0.7 and 25 μm; In general, wedge heights between 0.1 .mu.m and 1 mm come into question.

The operation of the texture of FIG. 3 will be explained with reference to FIG. The realistic assumption is made that the yarn 4 is always moved in the same direction + x through the measuring gap 3. In this case, any dirt particles 41 emitted by the yarn 4 also have a velocity component in the same direction + x. It follows that the dirt particles 41 always deposit from the same direction -x. The wedge-shaped elements 101 are now aligned so that they act as "protective shields" against the dirt particles 41. On the inclined surfaces of the wedge-shaped elements 101 and possibly on parts of the flat elements 102, therefore, dirt deposits 42 and thus contaminated zones 103 arise

By contrast, "slipstreams" of the wedge-shaped elements 101 on the flat elements 102 have dirt-free zones 104 which are virtually free of debris 41. The dirt-free zones 104 do not hinder the light on the one hand, and heavily soiled zones 103, on the other hand, are more advantageous than the situation with conventional devices having untextured surfaces which are relatively uniformly soiled throughout. In the device 1 according to the invention, there is sufficient undisturbed light transmission through the optical surface 100 or light reflection at the optical surface 100 , depending on the application - guaranteed.

The texture of the surface 100 shown by way of example in FIGS. 2-4 is only one of many possible textures. Instead of the wedge-shaped elements 101, the texture may contain elevations which have a rectangular, sinusoidal (wavy) and / or other shaped profile in longitudinal section (in the longitudinal direction x). Flat elements 102 do not necessarily have to be present. The shape choice and the

Dimensioning of the texture depends on parameters such as material of the component 10, width of the measuring gap 3, distance of the yarn 3 from the surface 100, speed of the yarn 4, size, material and state of aggregation of the most frequently expected Dirt particles 41 etc. from. All textures are in accordance with the present invention in common that they have elevations 101 and / or depressions 102, which are so designed and / or aligned that dirt 41 does not adhere or only in certain zones 103 liable where it does not bother. With knowledge of the invention, the skilled person will be able to design a texture suitable for a given application.

If the grating period p is small, i. H. is comparable to a wavelength of light used, optical diffraction may occur at the grating in optical devices. The light in other diffraction orders can be exploited specifically for the measurement. However, such a diffraction can also be detrimental because a part of the light is lost through them. To avoid diffraction, it may be advantageous to design the texture without periodic structures. Periodicity of the texture is not at all necessary for the present invention. FIG. 5 schematically shows an embodiment of a surface 100 with an aperiodic texture. The lines indicate wedge-shaped (or otherwise shaped) elements, as explained with reference to FIGS. 3 and 4. In this embodiment, the extent of a typical wedge-shaped element is less than the entire width of the surface 100. The wedge-shaped elements may be different in length from each other. They need not necessarily, as drawn in Figure 5, be aligned parallel to each other, yes, not even necessarily straight, but may be curved. They can be stochastically distributed over the surface.

Another texture which can be applied to surfaces 100 of the device 1 according to the invention is described in the publications WO-96/04123 A1 or WO-00/58410 A1. A textured in such a manner (not graphically illustrated here) surface 100 has ^® due to the lotus effect self-cleaning properties. Even liquids with low surface tension practically do not wet the surface 100, but form drops which do not adhere to the surface 100. To achieve these particular properties, the surface has 100 peaks and valleys, with the distance between the elevations ranging from 1 nm to 1 mm and the height of the elevations ranging from 1 nm to 1 mm. It can be a nanotextured surface. For the production of the surfaces 100 in the device 1 according to the invention, many different materials are possible. The surface 100 may be made of the same material as the component 10 that defines it, typically an optical glass or plastic suitable for optical applications. Alternatively, the surface 100 may consist of a coating that is applied to the component 10. Such a coating may in turn consist of a single layer or of several layers. Ideally, the coating should be scratch-resistant, have dirt-repellent properties, and / or counteract electrostatic charging. Materials that at least partially meet these requirements, such as ceramic materials or hydrophobic polymers such. As polytetrafluoroethylene (PTFE, Teflon ^® ).

The textured surface 100 for the inventive device 1 can be produced simultaneously with the component 10, for example by injection molding in a suitably textured form. Alternatively, the texture can be created later, z. B. by subsequent embossing, etching or coating. Corresponding microstructuring methods are known.

It is possible and may be advisable to clean the surface 100 occasionally or regularly. A cleaning can z. B. a rinse with a

Cleaning fluid, a blowing out with a gas and / or a mechanical cleaning with a brush, a cloth or the like include. As a result, contaminated zones 103 may become clean again or the self-cleaning of surface 100 may be supported.

Of course, the present invention is not limited to the embodiments discussed above. With knowledge of the invention, the skilled person will be able to derive further variants, which also belong to the subject of the present invention. LIST OF REFERENCE NUMBERS

1 device

2 housing 3 measuring gap

4 yarn

40 direction of movement

41 Dirt particles 42 Dirt deposit

5 source part

6 sensor part

7 light source 8 first Lichtzufuhrer

9, 9 'entrance prisms

10 first exit prism, component

11 second exit prism

12 second light feeders 13 third light feeders

14 first light sensor

15 second light sensor

100 surface 101 wedge-shaped element

102 flat element

103 soiled zone

104 Dirt-free zone x longitudinal direction y transverse direction z Height direction

Claims

Device (1) for testing a moving textile material (4), having a passage region (3) through which the textile material (4) is movable, and a component (10) having a surface (100) facing the textile material (4) ), characterized in that the surface (100) has a texture with elevations (101) and / or recesses (102), which counteracts contamination of the surface (100). 2. Device (1) according to claim 1, wherein the elevations (101) and / or depressions (102) are arranged and / or aligned such that the elevations (101) catch flying dirt particles (41) and so pollution of other zones ( 104) of the surface (100) prevent. 3. Device (1) according to claim 2, wherein the texture contains elevations (101), which have a wedge-shaped, rectangular and / or sinusoidal profile in the longitudinal section (x). 4. Device (1) according to claim 2 or 3, wherein the texture includes a substantially one-dimensional grid. 5. Device (1) according to claim 4, wherein the grating period (p) between 1 .mu.m and 1 mm, for example. Between 5 .mu.m and 50 .mu.m and preferably about 10 microns, is. The device (1) of claim 1, wherein the texture is such as to minimize the adhesion forces between the surface (100) and a liquid contacting it. 7. Device (1) according to one of the preceding claims, wherein the distance between the elevations (101) between 1 nm and 1 mm, preferably between 0.1 .mu.m and 200 .mu.m, and / or the height difference (h) between the elevations (101) and the depressions (102) between 1 nm and 1 mm, preferably between 0.1 .mu.m and 100 .mu.m. 8. Device (1) according to one of the preceding claims, wherein the surface (100) consists of the same material as the component (10) which limits it, preferably of a glass or a plastic. 9. Device (1) according to one of the preceding claims, wherein the surface (100) consists of a coating which is applied to the component (10), preferably made of a ceramic material and / or a hydrophobic Polymer-containing coating. 10. Device (1) according to one of the preceding claims, wherein the component (10) is an optical component and the surface (100) is an optical surface. 11. Device (1) according to one of the preceding claims, wherein the device (1) is designed for testing thread-like textile materials (4) and in particular as a yarn cleaner. 12. A method for testing a moving textile material (4), wherein the textile material (4) on a component (10) having a textile material (4) facing surface (100) is moved past, characterized in that the surface ( 100) is provided with a texture with protrusions (101) and / or depressions (102), which contamination of the surface (100) counteracts. 13. The method of claim 12, wherein the protrusions (101) intercept incoming dirt particles (41) and thus prevent contamination of other zones (104) of the surface (100). 14. The method of claim 12, wherein the texture minimizes the adhesion forces between the surface (100) and a liquid contacting it. 5. The method according to any one of claims 12-14, wherein the method is based on an optical measuring principle and the surface (100) interacts with the light used.