WIT Press

Aerodynamic Continual Weft Brake


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K. Adamek & P. Karel


This contribution describes the result of a theoretical design for the gentle aerodynamical braking of linear body (weft yarn) transported by air flow. The dynamic model for movement of a discrete mass points system is the main part of the system, the supposed braking force actions result from numerical flow modelling. Theoretical results of such modelling experiments, applied in practice, result in the very expressive production increasing in comparison with the state-of-the-art, together with expressive fabric quality increasing, too. Keywords: air jet weaving, weft brake, technical cloths, numerical flow modelling. 1 Description of the solved problem The air jet weaving is the most productive weaving system, where the weft yarn is transported through the weaving channel by air flow. The system of jet weaving was developed by the foregoer of Textile Machines Research Institute (VUTS) in Liberec – CZ and widespread in the whole world. In the last time the looms for production of very heavy technical fabrics are developed and realized in VUTS. A standard heavy fabric, as for instance very well known denim for blue jeans, is produced from yarns of a length mass of 100 g/km. A heavy technical fabric, as for instance woven wall covering, is produced from textured glass yarns of a length mass as far as 600 g/km. The standard problem of air jet weaving is remaining the same – in the initial phase of each insertion cycle there is necessary to accelerate the inserted weft yarn. But with increasing machine revolutions and inserted weft yarn mass, too, the new problem arises when the flying weft yarn should be stopped at the end of each pick, first of all by the weaving of very heavy materials. Example: The loom produces heavy technical fabrics in a weaving width of 2,0 m and with a weaving frequency of 9 Hz. The weft insertion takes 50% of


air jet weaving, weft brake, technical cloths, numerical flow modelling.