The embroidery machines are complex equipment with a single or multi-heads, which are controlled through PLC. In the case of embroidery machines, the sewing needles largely influence the quality of the manufactured products. Considering the influence of sewing needles on the quality of textile products, the existing works presented in the literature aimed to study the penetration force of the needles in the textile material the influence of the sewing needle temperature on the textile material and the influence of the vibrations of the embroidery machine . The wear of sewing needles is characterized by the changing of the size and shape of the needle, and the displacement of the needle axis relative to the vertical direction. Due to the wear of sewing needles, at high vibrations during the operation of the embroidery machines, there is wrinkling of the material on which the embroidery pattern is applied and breaking of the sewing thread can occur so that the embroidery machine has to be stopped. It is necessary to reposition the sewing needle with 6-10 stitch steps behind the trajectory to follow and the embroidery machine should be restarted. When the embroidering process restart, an overlap of the sewing thread occurs. Therefore, because of the wear of sewing needles defects appear on the embroidery surface of the product, the availability and thus the productivity of embroidery machines decrease, while the manufacturing costs are rising.
Within this context, it is necessary to schedule the moments of replacing the sewing needles of the embroidery machines based on the anticipation of their failure moments. In the past years, through the development of different types of sensors, the scheduling of the replacement of components has been moved from a statistical approach to a condition-based maintenance . Modern diagnostic techniques use sensors that determine the state of the equipment by comparing the signals received from the sensors at a given moment with signals corresponding to their good functioning status. more info
This paper presents some development work following up on previous research on monitoring and control techniques for high-speed industrial sewing machines. The main objective of the studies is to develop techniques and devices to allow a faster set-up, greater flexibility and higher product quality in industrial sewing operations. One of the main aspects of the sewing process is the interlacing of threads-stitch formation. It has been found that the on-line measurement of thread consumption can provide information about stitch adjustment and serve as a feedback variable for thread tension control. In this paper, an overview of this technique will be given, with particular focus on the quantification of bobbin thread consumption in lockstitch machines, one of the most widely used type of machine. In this specific case, measurement is difficult due to lack of physical space for the sensors. Click Here
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