KARL MAYER Textilmaschinenfabrik GmbH
Bühlstrasse 25
63179 Obertshausen
Germany




Optimum pattern yarn feed – even at high speed - KARL MAYER Textilmaschinenfabrik GmbH

KARL MAYER’s lace raschel machines offer a unique level of performance, which is the result of constant optimisation – right down to the very last detail. One of the most recent improvements relates to the yarn feed. The knitting process must be able to handle different levels of yarn consumption with a high degree of flexibility to produce the wide variety of different patterns – and this must be harmonised with the operating speed. Depending on the speed of the machines, two systems have therefore been used until now to deliver the pattern yarns, i.e. pattern beams and creels. Passive pattern yarn feed: The pattern beams run on ball bearings and are driven by the yarn let-off system at the knitting point – a solution which has its limitations at high machine speeds. Despite the use of balancing units, the physically induced mass inertia of the longitudinal shafts, together with the yarn warps which are arranged in a row, is so great that it can cause undesirable changes in the fabric appearance. Acceleration causes distortion, whilst braking results in undesirable compaction. Consequently the system using the pattern beams is limited when higher speeds are required. Creels were used previously to deliver the pattern yarns at higher speeds. However, these multi-position creel systems require a large amount of space, and especially a large number of bobbins which are loaded onto them – this is a disadvantage which, in particular, makes pattern development and processing small runs expensive and complicated. Pattern yarn feed via yarn-tension-controlled drives: As an alternative, KARL MAYER has now developed a pattern beam with active drive. The new system consists of a sensor for determining the yarn tension in one yarn for each pattern beam axle, and a motor system whose speed is controlled on the basis of the results of equalising the target/measured values. In this case, the desired values have to be input in advance. As a result, any fluctuations in consumption are equalised, even at high operating speeds, and any mass-induced imbalances are evened out. This means that the balancing units are no longer needed at the pattern beams but, above all, creels are no longer required to deliver the pattern yarns on high-speed lace machines. Market launch : This innovative control principle has already been used in practice by customers operating lace raschel machines. The system consists of a yarn-tension-controlled yarn delivery system and can be used with all pattern beams. It is based on the tried-and-tested servo system, which has been successfully used for many years now for driving the string bars. A new and improved version is currently being tested. The changes that are incorporated in this improved version relate to the use of a new type of motor and replacing the existing friction control system with toothed wheels for power transmission. The product should be ready for launching onto the market by the end of this year, and will give customers a range of options. Lace raschel machines with creels and pattern beams are still available if required.