Measuring and testing – Sheet – woven fabric or fiber – Filament
Patent
1993-09-28
1995-08-01
Raevis, Robert
Measuring and testing
Sheet, woven fabric or fiber
Filament
G01N 308
Patent
active
054371821
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates to the determination of properties of threads and more particularly to the determination of strength properties of warp threads in a warp.
The tensile test of textile and industrial yarns has always been an important test in quality control, specifically as regards both staple yarns and filament yarns. This is because the results of the tensile test make it possible to draw conclusions as to the production and therefore reveal production deficiencies; tensile-force and stretch values give indications as to the suitability of the raw material used and allow prognoses for the further processing of the yarn and for the final product.
Tensile tests of this kind are nowadays carried out off-line in a textile laboratory by examining the various yarn batches by random sampling. A known appliance for the tensile testing of yarns and twines is the tensile-testing system USTER TENSORAPID (USTER--registered trademark of Zellweger Uster AG) described in U.S. Pat. No. 4,338,824, and another tensile-strength tester is known from EP-A-O,403,988.
Textile laboratories equipped with modern test appliances are to be found very frequently in spinning mills and somewhat rarely in weaving mills. The reason for their limited use in weaving mills is to be sought in that the known test appliances do not allow testing on warp beams, and in that the strength data of non-sized yarns do not give sufficient indications as to the running behaviour on a specific weaving machine with a specific article. However, the fact that strength data are of interest in weaving mills too is proved by EP-A-O,240,074 which relates to a device for determining the strength properties of weft yarn, by means of which, as a rule, an entire yarn bobbin is always tested and at the same time is also used up.
In contrast, no tensile-strength testers for warp threads which can be integrated into the fabric production process are known, although any warp-thread break leads to a machine stoppage, and therefore the quality control of warp yarns should be of vital interest to any weaving mill.
SUMMARY OF THE INVENTION
The present invention, which relates to a method and a device for determining strength properties of the warp threads of a warp, is to allow strength properties to be determined as efficiently as possible and in a manner integratable into the fabric production process. Here, "integratable into the fabric production process" means that the determination of the strength properties takes place not off-line in a textile laboratory, but on-line as near as possible to a machine of the fabric production process. That this strength test is also to involve a minimum of warp-thread material used up for it is self-evident.
The method according to the invention is characterised in that the warp threads are clamped as a thread layer, are divided off individually from the thread layer and are stretched, with a simultaneous measurement of the tensile force and/or stretching, and in that these operations take place before the weaving process in a step of the weaving preparation process in which the warp threads are in the form of a prepared warp-thread layer.
The device according to the invention for carrying out this method is characterised by means for clamping the warp-thread layer, means for dividing off the warp threads and means for measuring the tensile force and/or stretching of the divided-off warp threads, said means for clamping the warp-thread layer forming an integral part of a warp-preparation machine, preferably of a knotting unit or of a drawing-in unit.
The invention starts from the new finding that, for efficient strength testing, the warp threads must be prepared as a thread layer, from which they can be separated in a simple way and fed to the measuring device. To put this finding into practice, the invention makes use of the fact that such a prepared thread layer is present many times in the preparatory process of the weaving mill. Thus, for example, during kno
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patent: 4338824 (1982-07-01), Brassel et al.
patent: 4703651 (1987-11-01), Mima
patent: 4805276 (1989-02-01), Plaschy
patent: 4825702 (1989-05-01), Cizek
patent: 5050437 (1991-09-01), Etter
Krebs Walter
Plaschy Martin
Raevis Robert
Zellweger Luwa AG
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