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Evaluation of the Length Distribution of Needle Thread within the Take-up Disc Zone of a Lockstitch Machine

Korycki R., Krasowska R.

Fibres & Textiles in Eastern Europe

2008

Vol. 16, no. 5 (70)

94--100

Evaluation of the length distribution of needle thread during stitch formation is necessary to determine the dynamic characteristics of a sewing machine, and the thread needed in this process. In this study, physical and mathematical models of the take-up disc are developed. The thread length for the full rotation range is determined as the geometrical distance between the active frictional barriers. The algorithm of calculations is introduced and implemented alternatively by means of the languages Fortran and C++, as well as by genetic algorithms. The length distribution of the needle thread obtained was verified by using simulations of the sequence and geometry of the frictional barriers, as well as experimental research of the purpose-oriented model of the take-up disc prototype.

Ocena rozkładu długości nici igłowej w procesie tworzenia ściegu jest niezbędna dla określenia charakterystyki dynamicznej maszyny szyjącej oraz wydatku nici w tym procesie. Opracowano model fizyczny oraz matematyczny tarczowego podciągacza nici. Długość nici dla całego zakresu pracy podciągacza została obliczona jako geometryczna odległość odpowiednich barier ciernych. Algorytmy obliczeń wykonano w językach Fortran i C++ oraz z wykorzystaniem algorytmów genetycznych. Uzyskany rozkład długości nici igłowej został zweryfikowany za pomocą symulacji geometrii układu barier podciągacza i doświadczalnie za pomocą jego modelu użytkowego.

Relationship between the tension impulses 01of needle thread in the lockstitch machine

Elmrych-Bocheńska J.

Zeszyty Naukowe. Włókiennictwo / Politechnika Łódzka

1999

z. 57

11-22

Lockstitch machines are characterised by the occurrence of particularly difficult operating conditions for needle thread. Consequently, the strength of the thread decreases, which leads to breakage while sewing and a decrease in the quality of the thread joint formed. Thread breakage in the zone of stitch formation takes place when one of the tension impulses, caused in the thread by the operation of the tools forming a stitch, affects the section of the thread weakened due to its being cyclically loaded. There are impulses of two kinds that are a potential threat in this situation: the tension of stitch tightening and, constituting a group of impulses, the tension of drawing the thread from the bobbin hook system. In the article, the results of investigations into the determination of a correlation between the impulse of stitch tightening and the impulse accompanying the thread leaving the bobbin hook system within one cycle of stitch formation as well as one cycle of operation of the thread take-up have been presented.