|Title of Invention||
A MEASURING DEVICE FOR THREAD TYPE TEST PIECES
|Abstract||A measuring device for thread-type test pieces having a measuring slit (2) with measuring Zones (6,7)for measuring the characteristics of a moving test piece, which are associated with a measuring device, Characterized by a coating (8) of an abrasion- resistant material, which is insenitive to wear by the moving test piece and covers the measuring zone in the measuring slit at least in part.|
|Full Text||MEASURING DEVICE FOR THREAD-TYPE TEST PIECES
The invention relates to a measuring device having a measuring slit with measuring zones, for measuring the characteristics of a moving thread-type test piece, which are associated with a measuring device.
Such a measuring device is known for yarn, for example from US-A-3,377,852. In this measuring device, two electrodes are installed in a slit in a plastics block, in such a way that together they form a measuring capacitor, the measuring field of which crosses the slit. The surface of this slit is coated with a thin layer of a material, the electrical conductivity of which is less than that of the electrodes. This is intended to ensure that locally occurring electrostatic charges arising as a result of contact with the moving yarn are distributed over this layer and dissipated.
A disadvantage of such a known measuring device is that defining the conductivity of the thin layer is very difficult, since it is necessary to prevent the layer from effecting an expansion of the surface area of the electrodes. Moreover, it only makes sense to provide this layer if the yarn to be measured is electrostatically charged and frequently touches or might touch the side walls of the slit. In addition, this layer may become worn, which also means that the electrical properties of the slit then change again.
It is further known that optically operating"devices are also available for measuring yarn, which likewise form a slit for the yarn. The beam path of an optical systemic extends over this slit, which optical system opens into the side walls of the slit.
Measuring slits in optically operating yarn measuring devices may be soiled by the yarn to be measured, which impairs optical measurement. This soiling may be
counteracted by a degree of self-cleaning by the moving yarn. In order effectively to combat soiling by self-cleaning, the dimensions of the measuring slit must be favourably adjusted. A disadvantage of such an arrangement is that, in the case of narrow measuring slits, undue wear of the side faces or of the elements installed therein has to be expected. However, this "restricts freedom of design in relation to such measuring slits and yarn measuring means in general.
The object to be achieved by the invention consists in increasing design options in the case of devices for measuring thread-type test pieces, in particular with regard to the construction of the measuring slit.
This is achieved according to the invention in that at least part of the measuring slit is covered with an abrasion-resistant coating, which is insensitive to wear by the moving yarn. This coating preferably covers electrodes, lenses or windows of optical devices embedded in the side walls of the measuring slit or parts thereof, as well as spaces or joints between the above-mentioned devices or electrodes and the other parts of the measuring slit. The measuring slit is coated by printing, dipping, vapour-deposition, sputtering or spraying with a material which preferably enters into chemical combination with the surface of the above-mentioned parts in the slit and remains applied in a layer thickness of for example 20 -3 0 nm.
The advantages achievable thereby are in particular that the service life of the measuring slit may be increased. Another advantage consists in the fact that the measuring field, i.e. the space in which there extends the beam path of an optical system or the electrical field of a capacitive system, may be reduced. This may be achieved on the one hand by a reduced slit width and on the other hand
by a smaller surface area of the electrodes or the optical elements which adjoin the measuring slit. A further advantage consists in the fact that the self-cleaning effect of the measuring slit may be better exploited. This may be achieved by a reduced slit width. Soiling or deposits may then be more reliably removed by the test piece itself. This action is the greater, the narrower is the measuring slit and the more probable is contact between the test piece or protruding parts thereof and the side walls. Or, it is possible to dispense with lateral guidance, if the position of the test piece in the slit is of no importance.
A narrower slit .also has the advantage that the effect of the shape, i.e. the fact that the cross section of the test piece may not be circular but possibly oval, on measurement of the mass of the test piece is reduced considerably. This is because, in a narrow slit, the yarn no longer appears to the electrodes or the optical elements as a flat body, as in a very wide slit.
The design according to the invention of a measuring slit also creates better conditions for installing an optical and a capacitive measuring system together in a measuring slit.
The invention is explained in more detail below with the aid of an Example and with reference to the attached Figures, in which:
Figure 1 is a schematic representation of a measuring slit,
Figure 2 shows part of a measuring device with a measuring slit and
Figure 3 is a schematic representation of part of a measuring slit.
The Figures are schematic, simplified representations of a part 1 of a measuring device with a measuring slit or slit 2 for a test piece 3, here for example a yarn. Elements 6 and 7 of measuring devices are attached to side walls 4 and 5 of the slit 2 or embedded in the side walls 4, 5. These elements 6, 7 may comprise electrodes of a capacitively operating measuring system or windows, faces of prisms, lenses or other components of an optically operating measuring system. Corresponding elements 6" and 7" are located in the opposing side wall. The elements 6, 6" or 7, 7" define on the side walls 4, 5 measuring zones of a measuring device, known per se and therefore not described in any more detail here, for measuring^ yarn characteristics such as mass, diameter, hairiness, colour, foreign fibre content etc. A coating 8 here partly covers the side wall 4 with the elements 6 and 7. This coating may cover only the elements 6, 6", 7, 7" or only the base 9 or the encire side walls 4 and 5 and optionally also the base 9 of the slit 2 and consists of an abrasion-resistant material, which is preferably transparent to optical measuring systems or conductive with regard to capacitive measuring systems. The coating preferably has glass-like characteristics, i.e. it is transparent, hard and smooth, such that it offers little resistance to the test piece if touched. The coating may be obtained for example by inorganic material synthesis and form a so-called nano-composite, with which for example a glass-like, scratch-resistant but non-fragile or brittle surface may be achieved. The coating may be applied by dipping the part 1 into the coating material or by spraying thereof. The coatina may consist of a so-called sol, which enters into chemical combination with the material at the surface of the measuring slit. Such sols are known from sol-gel technology.
The coating makes it possible, for example, to restrict the width B of the slit to a value which corresponds to 4 to 10
times the diameter of the test piece 3 or to provide novel slit shapes, as shown in the Figures described below.
Fig. 2 shows part of a measuring device with a coated measuring slit 10, which may be subdivided into an inlet part 11 and a measuring part 12. A test piece 13 requiring measurement is located in the measuring part 12. Another arrangement of an inlet part 11" is also revealed, which is not arranged as usual in the same axis as the measuring part 12, but rather issues to the side. Both inlet parts 11 and 11" screen the measuring part 12 against foreign light by means of their narrow cross section, which is advantageous in^optical measuring systems. This applies to a greater extent in the case of the inlet part 11".
The coating according to the invention allows the measuring part 12 also to be constructed with three-dimensionally curved side faces 17, which also act as thread guides, as is revealed by Fig. 3.
Fig. 3 shows a view of the measuring part 12 starting from a section plane as indicated by arrows A-A in Fig. 2. This reveals the end areas 14 and 15 together with a central area 16, wherein the central area IS has a larger cross section than the end areas 14, 15. This means here too that the base, i.e. that part of the slit designated S in Fig. 1, no longer runs parallel to the test piece and is not flat. In the embodiment shown, the base is deeper in the middle of the slit than at the ends. It is thus possible, for example, to provide only the end areas 14, 15 with a layer 17, 18 according to the invention, such that the latter may assume the function of a guide for the test material. Thus, many other shapes are also feasible for the measuring part 12. Nevertheless, the area 16 may be provided with a layer for the better protection thereof. If the slit 2 is continuous at its base, i.e. is constructed without discontinuities such as steps, deposits are also
removed continuously or entrained by the test material. This is particularly important in the case of test pieces which, like yarns, consist of fibres.
1. A measuring device for thread-type test pieces having
a measuring slit (2) with measuring zones (6, 7), for
measuring the characteristics of a moving test piece,
which are associated with a measuring device
characterised by a coating (8) of an abrasion-
resistant material, which is insensitive to wear by
the moving test piece and covers the measuring zone in
the measuring slit at least in part.
2. A measuring device according to claim 1, characterised in that the coating consists of material exhibiting glass-like characteristics.
3. A measuring device according to claim 1, characterised in that the coating is formed by a nano-compcsite obtained from inorganic material synthesis.
4. A measuring device according to claim 1, characterised in that the coating exhibits a thickness of 20-30 nm.
5. A measuring device according to claim 1, characterised in that the measuring slit with the coating exhibits a width (B) which corresponds to 4 to 10 times the diameter of the test piece.
6. A measuring device according to claim 1, characterised in that the coated measuring slit comprises an inlet part (11) and a measuring part (12) .
7. A measuring device according to claim 6, characterised in that the inlet part comprises a narrower cross section than the measuring part (12).
8. A measuring device according to claim 6, characterised in that the measuring part comprises three-dimensionally curved side faces (17).
9. A process for producing a measuring device according to claim 1, characterised in that a coating is applied at least to parts of the measuring slit, wherein the coating enters into chemical combination with the material at the surface of the measuring slit.
10. A measuring device substantially as hereinbefore described with
reference to the accompanying drawings.
11. A process for producing a measuring device substantially as hereinbefore
described with reference to the accompanying drawings.
|Indian Patent Application Number||IN/PCT/2001/95/CHE|
|PG Journal Number||13/2008|
|Date of Filing||19-Jan-2001|
|Name of Patentee||USTER TECHNOLOGIES AG|
|Applicant Address||Wilstrasse 11, CH-8610 Uster,|
|PCT International Classification Number||G01L 5/04|
|PCT International Application Number||PCT/CH1999/000340|
|PCT International Filing date||1999-07-23|